14urn:lsid:arphahub.com:pub:69C4EDC7-0CE2-5AB0-81F2-EA3B3CC9D365urn:lsid:zoobank.org:pub:777322AB-37CC-4A41-B3C2-83A76AAD4F84Deutsche Entomologische ZeitschriftDEZ1435-19511860-1324Pensoft Publishers10.3897/dez.72.158689158689Research ArticleStaphylinidaeFaunistics & DistributionIdentification keyTaxonomyCenozoicFar EastTaxonomy of Homoeusa Kraatz, 1856 (Coleoptera, Staphylinidae, Aleocharinae) from the East Palearctic: II. Revision of Japanese speciesNozakiTsubasadosanko.lathrobium@gmail.comhttps://orcid.org/0000-0002-2419-496812MaruyamaMunetoshihttps://orcid.org/0000-0003-4531-10082Entomological Laboratory, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka 819-0395, JapanKyushu UniversityFukuokaJapanThe Kyushu University Museum, Fukuoka 812-8581, JapanThe Kyushu University MuseumFukuokaJapan
2025031220257225255553BAB9E83-C589-572F-88F9-1C23A30E73C10F162CF0-9B4E-476B-A832-91BBCCD00D6A1205202509102025Tsubasa Nozaki, Munetoshi MaruyamaThis is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.https://zoobank.org/0F162CF0-9B4E-476B-A832-91BBCCD00D6A
Members of the myrmecophilous rove beetle genus Homoeusa Kraatz, 1856 are symbiotically associated with ants of the genus Lasius Fabricius, 1804 with a high degree of host specificity, making them biologically intriguing subjects for studying myrmecophily and host–parasite interactions. Their identification, however, remains challenging. Diagnostic characteristics, particularly the genitalia, have not been well documented for the three previously described species of the genus from Japan, and the presence of undescribed species has been suggested. In this study, we revise the taxonomy of Japanese Homoeusa, providing detailed descriptions and illustrations of seven species, including three new species: Homoeusatranslucidasp. nov., Homoeusabrevitarsissp. nov., and Homoeusagiganteasp. nov. Additionally, we present ecological information for each species and discuss their interactions with their host ants.
AleocharinedescriptionDinardinainquilineLasiusmyrmecophilynew speciesrove beetlesJSPS KAKENHI Grant Number JP22770085, JP23KJ1740Introduction
The genus Homoeusa Kraatz, 1856 is a myrmecophilous rove beetle group associated with Lasius Fabricius, 1804 ants (subfamily Formicinae, tribe Lasiini). Currently, this genus comprises 12 species that are distributed across the Holarctic region (Nozaki and Maruyama 2022a). This series of papers aims to revise the species-level taxonomy of the genus in the East Palearctic region, with a particular focus on the fauna of East Asia and the Russian Far East. The present paper focuses on the Japanese members of this genus.
To date, six species are known from Japan. Of these, four were described by David Sharp based on specimens collected by George Lewis (Sharp 1874, 1888). Subsequently, Sawada (1970b) described a single species, H.prolongata Sawada, 1970. In our previous paper, we formally verified the combination of Homoeusarufescens (Sharp, 1874) and described one species, H.ovata Nozaki & Maruyama, 2022. Detailed descriptions and illustrations of the genitalia are provided for three species: H.rufescens, H.prolongata, and H.ovata. However, this information is not available for the remaining three species.
Through extensive collection efforts and the examination of historical specimens, two previously undescribed species have been discovered (Maruyama et al. 2013). Additionally, a previously unknown species from the Kii Peninsula of Honshu has been identified, further emphasizing the need for comprehensive taxonomic studies in underexplored regions. This paper builds on the legacy of previous studies by revisiting historical specimens and integrating new materials, offering a complete re-evaluation of the Japanese Homoeusa species.
The present paper provides redescriptions of four previously known Japanese species and descriptions of three new species. Besides detailed morphological descriptions, this study provides ecological insights into the species of Homoeusa. These include geographic distribution, host ant associations, seasonal activity patterns of adults, collection methods, and behaviors observed in the presence of host ant workers. Such ecological observations not only complement taxonomic findings but also contribute to a broader understanding of the interactions between these beetle inquilines and their ant hosts. Finally, we discuss aspects of their life cycle and behavior, highlighting potential adaptive traits that may have evolved in response to their myrmecophilous lifestyles.
Materials and methods
The materials used in this study have been deposited in the following institutions and private collections:
cKam The private collection of Hiromu Kamezawa (Saitama-ken, Japan)
cSch M. Schülke collection, Berlin, Germany (belonging to Museum für Naturkunde, Berlin, Germany)
EUMJ Ehime University Museum, Japan (H. Yoshitomi)
HUM The Hokkaido University Museum, Sapporo (M. Ôhara)
IPMM Iwate Prefectural Museum, Morioka, Japan (S. Watanabe)
KPMNH Kanagawa Prefectural Museum of Natural History (K. Watanabe)
KUM The Kyushu University Museum (M. Maruyama)
NHM The Natural History Museum, London (K. Matsumoto)
NHMW The Natural History Museum Vienna (M. Seidel)
NSMT National Museum of Nature and Science, Tsukuba (S. Nomura)
OUAVM The Laboratory of Entomology, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan
SCM Sagamihara City Museum, Kanagawa, Japan (S. Shimamoto)
SPMN Museum of Natural and Environmental History, Shizuoka (T. Kishimoto)
TUA Laboratory of Entomology, Faculty of Agriculture, Tokyo, University of Agriculture, Kanagawa, Japan (T. Ishikawa)
The morphological observations were made using an Olympus SZX12 stereomicroscope. For measurements, 5–15 photographs per specimen were captured using a Canon EOS Kiss X5 camera mounted on the Olympus SZX12 stereomicroscope, and the following parts were measured using ImageJ 1.54g.
BL approximate body length
AL antennal length
HW head width
PL pronotal length
PW pronotal width
EL elytral length (sutural length from apex of scutellum to posterior margin of elytra)
EW elytral width
HTL hind tibial length
For the dissection and preparation of permanent slides, Maruyama (2004) was referenced. Habitus photographs were taken with a Canon 7D camera, Canon MP-E 65 mm f/2.8 1–5X macro lens, and Neewer TT560/1Y strobe. The images were stacked using ZERENE STACKER ver. 1.04 (Zerene Systems, LLC). The dissected parts were drawn using a Nikon Eclipse Ci microscope with an Olympus drawing tube attached with a Nikon Y-IDT and imaged using a Canon Eos Kiss X8i mounted on an Olympus BX50 microscope.
The terminology of the internal structure of the male aedeagus follows the description of H.prolongata (Sawada 1970b), and that of the spermatheca follows Maruyama (2006), as shown in Fig. 1A, B, respectively. A distribution map was constructed using QGIS 3.34 Prizren.
Host ant workers collected with the Homoeusa species were mostly identified by MM and F. Ito, and some by TN, K. Kinomura, and Y. Hisasue. Based on the scientific names of Lasius ants, we followed Bolton (1995), Radchenko (2005), and Boudinot et al. (2022), who referred to species groups as in Nozaki and Maruyama (2022a). The identified symbiotic host species and relevant data are as follows.
Lasiusfuliginosus group
LFNLasiusnipponensis Forel, 1912
LFcfFLasiuscf.fuliginosus
LFMLasiusmorishitai Yamauchi, 1979
LFSLasiusspathepus Wheeler, 1910
LFOLasiusorientalis Karavaiev, 1912
Lasiusniger species group
LNHLasiushayashi Yamauchi & Hayashida, 1970
LNJLasiusjaponicus Santschi, 1941
LNPLasiusproductus Wilson, 1955
LNSLasiussakagamii Yamauchi & Hayashida, 1970
Lasiusumbratus group
LUMLasiusmeridionalis (Bondroit, 1920)
LUULasiusumbratus (Nylander, 1846)
In addition to collections by MM, newly collected Homoeusa specimens by TN from 2021 to 2024 were included. Collection methods usually involved picking the insects from foraging trails or nests under stones. Shifting litter around foraging trails or destroying nests in decayed wood was also adopted. TN frequently set bait near foraging trails/nests in the litter or soil and under stones. If successful, it resulted in a small swarm of worker ants (Fig. 1C), and Homoeusa adults could be collected by shifting such clusters. Some specimens were collected using flight intercept traps (FIT) and a malaise trap.
Explanations on research methods. A. Terminology of aedeagal median lobe (Homoeusaprolongata); al – apical lobe; av – apical valves; cp – copulatory piece; B. Terminology of spermatheca (Homoeusalaevigata); ap – apical part; bp – basal part; C. A simple bait trap set under stone with a swarm of Lasiusmeridionalis; D. A small camera shooting video of a Lasiusfuliginosus group sp. foraging trail; E. Indoor observation setup using a plastic container with plaster.
Type materials deposited in NHM. A–C. The habiti of the type specimens of three species; A. The holotype of Homoeusalaevigata Sharp, 1888, male; B. The lectotype of Homoeusajaponica Sharp, 1874, male; C. The holotype of Homoeusalongicornis Sharp, 1888, male; D, E. The labels pinned with each specimen (all photographed by Keita Matsumoto).
https://binary.pensoft.net/fig/1483272
Behavioral observations were conducted at their habitat outdoors and at the laboratory or accommodations just after collecting (mentioned as “indoors” or “indoor observation”). Videos were recorded using a Camera Ricoh WG5, which was set in front of the foraging trails outside (Fig. 1D) or indoors in plastic containers with plaster (Fig. 1E). Sometimes during indoor observations, a Nikon Digital Sight DS-Fil camera attached to a microscope Leica S8APO was also used. Still images were captured from the videos using Adobe Premiere Elements 2025.
All figures were edited and combined with Photoshop Elements 2025.
See Nozaki and Maruyama (2022a) for a detailed synonymic list and the diagnosis of this genus.
Remarks.
No apparent sexual dimorphism other than in the genitalia or terminalia has been reported in this genus. However, based on extensive examination of several species, females were often found to have shorter and denser stout setae on the middle posterior margin of the 8th sternite than males did (Fig. 9F, G). Moreover, there are more or less interspecific variation in the marginal shape of the 8th sternite on each sex. Therefore, we provide illustrations and descriptions of this characteristic for all the species, including the well-described species in our previous papers (Nozaki and Maruyama 2022a, 2022b), Homoeusarufescens and H.ovata.
To measure the antennae, we provided the width and aspect ratio of each segment in the previous paper. However, they usually have elliptical cross-sections, which can cause instability during measurement. Therefore, we provided the relative length of each segment instead.
The males have various parameral apical lobe shapes and arrangements of the four setae across species. Although strict homology is not available for these four setae, for the convenience of a comparative description, we named them as Sawada (1970b) did for H.prolongata. Each seta typically has the following characteristics in Homoeusa (e.g., Fig. 13H): a, longest and distributed at the most basal position; b, medium in length and distributed dorsally; c, medium in length and distributed ventrally; d, shortest, thinnest, and distributed at the most apical position.
Key to species of <italic><tp:taxon-name><tp:taxon-name-part taxon-name-part-type="genus" reg="Homoeusa">Homoeusa</tp:taxon-name-part></tp:taxon-name></italic> in Japan
1
Pronotum strongly transverse, 1.84–2.05 as wide as long (Fig. 4B); pronotum and elytra sparsely covered with modified stout setae (Fig. 4C)
Homoeusatranslucida sp. nov.
–
Pronotum moderately transverse, 1.38–1.80 times as wide as long (e.g., Fig. 7B); pronotum and elytra moderately densely covered with normal setae (e.g., Fig. 7B, C)
2
2
Metatarsus shorter than half of the metatibia (Fig. 17F, G)
Homoeusabrevitarsis sp. nov.
–
Metatarsus longer than half of the metatibia (Fig. 3E)
3
3
Antennal segment 10th more transverse (e.g., Fig. 13A)
4
–
Antennal segment 10th less transverse (Fig. 9A, B)
6
4
Pronotum weekly transverse (PW/PL, 1.38–1.49); median lobe of aedeagus having round flattened projection on ventral side (fig. 12 in Nozaki and Maruyama 2022a)
Homoeusarufescens (Sharp, 1874)
–
Pronotum strongly transverse (PW/PL, 1.54–1.68); median lobe of aedeagus without round flattened projection on ventral side
5
5
Metaventral process distinctly produced (fig. 22 in Nozaki and Maruyama 2022a); median lobe of aedeagus, apical lobe s-shaped in lateral view with small lanceolate flattened projection on ventral side (fig. 23 in Nozaki and Maruyama 2022a)
Homoeusaovata Nozaki & Maruyama, 2022
–
Metaventral process slightly or indistinctly produced (e.g., Fig. 13D); median lobe of aedeagus, apical lobe not s-shaped without flattened projection
Homoeusaprolongata Sawada, 1970b
6
Postero-lateral angle of pronotum acute (e.g., Fig. 15B); metaventral process slightly or indistinctly produced (e.g., Fig. 15D)
7
–
Postero-lateral angle of pronotum obtuse or around 90 degrees (e.g., Fig. 9C); metaventral process distinctly produced (e.g., Fig. 9E)
8
7
Pronotum and elytra covered with long setae (Fig. 15B, C); elytral postero-lateral notch deep (Fig. 15B); mesocoxal cavities almost separated (Fig. 15D)
Homoeusagigantea sp. nov.
–
Pronotum and elytra covered with distinctly shortened setae (Fig. 7B, C); elytral postero-lateral notch shallow (Fig. 7B); mesoventral process reaching only middle of mesocoxal cavities (Fig. 7D)
Homoeusalaevigata Sharp, 1888
8
Apical lobe of paramere moderately long (Fig. 9I, J), length about half of whole paramere, apex simply round
Homoeusajaponica Sharp, 1874
–
Apical lobe of paramere extremely long (Fig. 11I), length a little over half of whole paramere, apex blade-shaped
Homoeusalongicornis Sharp, 1888
AnimaliaColeopteraStaphylinidae41E2F413-A9C8-51B5-B401-F51195E80F50Homoeusatranslucidahttps://zoobank.org/B3ED5737-79D9-4A24-B513-344F726D937BNozaki & Maruyamasp. nov.Figs 3A, 4A–I, 5A, B Japanese name: Sukashi-hirata-ariyadori“Homoeusa sp.4”: Saitoh et al. 2017: 33, fig. 65 (recorded from Kanagawa-ken). “Oxypodini? sp.2”: Nishida 2019: 135, fig. 11 (recorded from Saga-ken). Material examined.
Holotype (Fig. 1A) • ♂; “Mt. Minoyama, Minano,” / “Saitama, Japan, alt. 500-” / “560 m; MC: 5439-00-69.” / “21.V.1999 M. UCHIDA” (KUM). Paratypes. Japan: Hokkaido • 1♀; Nopporo Forest Park, Sapporo-shi; 24.V. & 5.VI.2008; Tomáš Lackner leg. (NHMW). Honshu: Kanagawa-ken • 1 ex.; Yakunimi-yama, Hadano-shi; 10.V.2013; O. Saitoh leg. (KPMNH) • 1♀; same locality; 24.V.2014; O. Saitoh leg. FIT (KPMNH) • 1♂; same locality; 8.VI.2014; O. Saitoh leg. FIT (KPMNH). Shimane-ken • 1 ex.; Urahikimi, Masuda-shi; 6.VI.1998; S. Nomura leg. (KUM). Okayama-ken • 1 ex.; Nagi-yama, Nagi-chô; 17.V.2005; W. Suzuki leg. (KUM). Shikoku: Ehime-ken • 1 ex.; Mt. Sara-ga-mine, Toon-shi; 13.VII.2008; Y. Yamauchi leg. (EUMJ). Kochi-ken • 1 ex.; Kajigamori, Ôtoyo-chô; 20.V.1951; M. Miyamoto leg. (EUMJ). Kyushu: Fukuoka-ken • 1 ex.; Takasubaru, Mt. Hikosan [33.4883, 130.9174], Soeda-machi; 27.VI.2021; TS. (Tsubasa) Nozaki leg. LUM (KUM) • 1 ex.; Bio. lab. KU. Mt. Hikosan, Soeda-machi; 28.III–27.IV.2023; J. Abe leg. Malaise trap (KUM). Saga-ken • 1♂; Mt. Seira, Imari-shi; 28.V.1984; S. Nomura leg. (KUM) • 1♂; Kurokami-yama, Arita-cho; 18.V.2018; M. Nishida leg. FIT (KUM).
Diagnosis.
This species can be easily distinguished from the other species of the genus by the following combination of characteristics: body color yellowish orange; pronotum strongly transverse (PW/PL, 1.84–2.05), postero-lateral angle distinctly acute (Fig. 4B); metaventral process weakly produced (Fig. 4D); pronotum and elytra sparsely covered with modified stout setae (Fig. 4B, C); median lobe of aedeagus apical lobe straight, apex round and slightly humped in lateral view, apical valves very large and cheliform (Fig. 4G); spermatheca (Fig. 4I) L-shaped, basal part very long. This species is slightly similar to H.gigantea sp. nov. in color but differs in its pronotal and setal shapes.
Description.
Body (Figs 3A, 5B) small, broad; dorsal surface mostly polished.
Habiti of Japanese Homoeusa spp. A.Homoeusatranslucida sp. nov., holotype, male; B.Homoeusalaevigata Sharp, 1888, male from Nagano-ken; C.Homoeusajaponica Sharp, 1874, male from Fukuoka-ken; D.Homoeusalongicornis Sharp, 1888, male from Hokkaido; E.Homoeusaprolongata Sawada, 1970b, male from Nagano-ken; F.Homoeusagigantea sp. nov., holotype, male; G.Homoeusabrevitarsis sp. nov., holotype, male.
Homoeusatranslucida sp. nov. A. Antenna; B. Pronotum and elytra; C. Zoomed view of elytron; D. Meso- and metaventrite; E, F. Posterior margin of 8th sternite; E. Male; F. Female; G. Median lobe of aedeagus from lateral view; H. Paramere of aedeagus from lateral view; I. Spermatheca.
Homoeusatranslucida sp. nov. A. Distribution map; black star – the type locality; white circles – collection data examined in this paper; B. A photograph of a living adult collected with Lasiusmeridionalis at Mt. Hikosan, Fukuoka-ken, Kyushu.
https://binary.pensoft.net/fig/1483275
Head large; color yellowish orange; eyes large. Antennae (Fig. 4A) long; relative length of each antennal segment from first to 11th, 2.48: 1.96: 1.39: 1.22: 1.04: 1.09: 1.00: 1.15: 1.15: 1.37: 3.26.
Thorax.
Pronotum (Fig. 4B) subrectangular, strongly transverse (PW/PL, 1.84–2.05), widest near middle, postero-lateral angle distinctly acute, posterior margin distinctly sinuate, color yellowish orange, subtransparent, surface sparsely covered with modified stout setae and punctures, gently polished without reticulation. Elytra (Fig. 4B, C) slightly widened posteriad, widest at middle, then narrowed roundly, posterior margins shallowly notched near lateral corners, color yellowish orange, subtransparent, surface sparsely covered with modified stout setae and punctures, gently polished without reticulation. Hind wings developed. Mesoventral process (Fig. 4D) narrow, with weak medial carina, apex gently pointed, reaching posterior 1/3 of mesocoxal cavities, Metaventral process weakly produced.
Abdomen elongate, narrowed posteriad; surface sparsely covered with short setae and each posterior margin with long stout setae; covered with fine vertical furrows.
Male: 8th sternite (Fig. 4E) widely protruding at middle of posterior margin; median lobe of aedeagus (Fig. 4G) elongate, length about 0.57 mm, apical lobe straight, apex round and slightly humped in lateral view, apical valves large and cheliform, dorsal arms boot-shaped; basal part of copulatory piece very large and having claw-shaped projection, basal corner acutely pointed. Paramere (Fig. 4H) length about 0.59 mm; apical lobe of paramere long, length over 1/3 of whole paramere, curved ventrally, slightly dilated apicad; four setae, c located a little more apically than b; velum narrow and membranous.
Female: 8th sternite (Fig. 4F) slightly protruding at the middle of posterior margin; spermatheca (Fig. 4I) L-shaped, basal part very long, apex of basal part not swollen, base almost straight and only slightly swollen.
Measurements (in mm) and ratios.
Body parts (N = 10): BL ≈ 2.13–2.91; AL, 0.93–1.07; HW, 0.51–0.57; PL, 0.5–0.59; PW, 1–1.13; EL, 0.47–0.52; EW, 0.98–1.16; HTL, 0.69–0.76; PW/PL, 1.84–2.05; AL/PL, 1.69–1.95; HTL/PL, 1.29–1.46.
Distribution.
Japan (Honshu, Shikoku, Kyushu) (Fig. 5A).
Symbiotic hosts.
Lasiusumbratus species group: L.meridionalis (only single example).
Bionomics.
Two individuals were collected by FIT, and a single individual was collected by the malaise trap. The behavior with the host ants is unknown.
Remarks.
This species is relatively rare, and most specimens have no information regarding their host ants. However, a single specimen (Fig. 5B) was collected with L.meridionalis using a bait trap set by TN under the stone where the ant trail was located.
Etymology.
The specific name is derived from the Latin adjective, which means “transparent” and refers to the character of the pronotum of this new species.
AnimaliaColeopteraStaphylinidaeE7F592F5-B108-547C-A51B-F5BB3E8692DAHomoeusarufescens(Sharp, 1874)Fig. 6A–C, G (Japanese name: Hoso-hirata-ariyadori)ThiasophilarufescensSharp, 1874: 5; Fenyes 1919: 393 (catalogue); Bernhauer and Scheerpeltz 1926: 771 (catalogue); Smetana 2004: 488 (catalogue).Homoeusarufescens: Maruyama and Zerche 2014: 17 (mentioning actual generic affiliation); Schülke and Smetana 2015: 682 (catalogue); Nozaki and Maruyama 2022a: 42 (the combination confirmed).Additional material.
Japan: Honshu: Ibaraki-ken • 2 exs.; Asahi-tôge, Tsuchiura-shi; 8.V.2022; Y. Komatsuzaki leg. (KUM) • 1 ex.; Nagai, Tsuchiura-shi; 27.IV.2022; Y. Komatsuzaki leg. (KUM). Chiba-ken • 5 exs.; Shimin-nomori Yachô-no-mori, Toyooka, Futtsu-shi; 10.V.2007; H. Ono leg. (KUM). Tokyo-to • 1 ex.; Mt. Takao (alt. 450 m), Hachiôji-shi; 4.VI.2001; M. Maruyama leg. LFS (NHM). Kanagawa-ken • 1 ex.; Nonkendainomori, Enkaizan, Yokohama-shi; 3.V.1991; K. Kubo leg. (SPMN). Nagano-ken • 2 exs.; Fuji, Satoyamabe, Matsumoto-shi; 21.V.2004; T. Komatsu leg. (KUM) • 1 ex.; Fuji, Satoyamabe, Matsumoto-shi; 9.VI.2004; T. Komatsu leg. (KUM). Gifu-ken • 3 exs.; Mitahora, Gifu-shi, 10.VI.2013; K. Kinomura leg. (KUM) • 2 exs.; Hirugano Bunsuirei Park, Gujo-shi; 10.VI.2013; K. Kinomura leg. (KUM). Shizuoka-ken • 2 exs.; Kumazaka, Izu-shi, 30.V.2022; T. Tenma leg. (KUM). Aichi-ken • 1 ex.; Jôkôji-kôen, Seto-shi; 4.V.2023; T. Tenma leg. (KUM). Osaka-fu • 3 exs.; Sakurai [34.8828, 135.6525], Shimamoto-chô; 9.V.2021; Y. Takatani leg. LFS (KUM). Shikoku: Kagawa-ken • 1 ex.; Shirahige-jinja, Ayagami-chô; 25.IV.2004; H. Fujimoto leg. LFM (KUM). Kochi-ken • 2 exs.; Ashizuri-misaki (alt. 120 m) [32.7480, 133.0136], Tosashimizu-shi; 21.V.2024; TS. Nozaki leg. (KUM). Kyushu: Fukuoka-ken • 2 exs.; Bio. Exp. Center of Kyushu Univ., Mt. Hikosan, Soeda-machi; 24.IV.2021; N. Tsuji leg. (KUM) • 1♂; Biol. Lab. KU, Hikosan (alt. 750 m), Soeda-machi; 22.V.2011; M. Maruyama & T. Kanao leg. (KUM). Miyazaki-ken • 1 ex.; Ômoridake forest road (alt. 600 m) [32.0435, 131.1973], Aya-machi; 12.VI.2024; TS. Nozaki & T. Kinoda leg. LFS (KUM).
Diagnosis.
See Nozaki and Maruyama (2022a).
Additional description.
Relative length of each antennal segment from first to 11th, 2.27: 1.63: 1.37: 1.27: 1.02: 1.02: 1.00: 1.05: 1.07: 1.44: 3.34. Hind wings developed.
Male. 8th sternite (Fig. 6A) weakly round at posterior margin; four setae of parameral apical lobe (Fig. 6C) normally arranged.
Homoeusarufescens (Sharp, 1874) and Homoeusaovata Nozaki & Maruyama, 2022b. A–C, G.Homoeusarufescens; D–F, H.Homoeusaovata. A, B, D, E. Posterior margin of 8th sternite; A, D. Male; B, E. Female; C, F. Parameral apical lobe (modified from figs 13, 24 in Nozaki and Maruyama 2022a); G, H. Distribution map; black star – the type locality; white circles – collection data examined in Nozaki and Maruyama (2022a); black circles – additional data examined in this paper.
https://binary.pensoft.net/fig/1483276
Female. 8th sternite (Fig. 6B) gently round at posterior margin.
AnimaliaColeopteraStaphylinidae49EEBEA6-0488-591F-94B6-A0D4266766A7HomoeusaovataNozaki & Maruyama, 2022Fig. 6D–F, H (Japanese name: Hime-hirata-ariyadori)HomoeusaovataNozaki and Maruyama 2022b: 1 (provideing depository); Nozaki and Maruyama 2022a: 48 (detailed description but unavailable).“Homoeusa sp.:” Maruyama et al. 2013: 24 (distribution and bionomics mentioned). Additional material from Japan.
Relative length of each antennal segment from first to 11th, 2.31: 1.98: 1.48: 1.29: 1.17: 1.00: 1.14: 1.14: 1.26: 1.4: 3.36. Hindwings developed.
Male. 8th sternite (Fig. 6D) gently round at posterior margin; apical lobe of paramere (Fig. 6F), setae b and c irregularly distributed at the acute corner on dorsal side.
Female. 8th sternite (Fig. 6E) gently round at posterior margin.
Distribution.
Russia (Primorskyi krai), Korea, Japan (Hokkaido, Honshu, Shikoku, Kyushu) (Fig. 6H).
This species is distinguished from other species of the genus by the following combination of characteristics: body blackish, polished; pronotal postero-lateral angle acute (Fig. 7B, C); elytra distinctly widened posteriad entirely (Fig. 7B); pronotum and elytra covered with shortened setae (Fig. 7B, C); metaventral process hardly produced; male 8th sternite (Fig. 7E) slightly emarginated at the middle of the posterior margin; median lobe of aedeagus bulbous; basal part of copulatory piece large. This species is similar to H.gigantea sp. nov. in body size and shape but can be distinguished by its blackish color and shortened setae on the pronotum and elytra.
Homoeusalaevigata Sharp, 1888. A. Antenna; B. Pronotum and elytra; C. Zoomed view of elytron; D. Meso- and metaventrite; E, F. Posterior margin of 8th sternite; E. Male; F. Female; G. Median lobe of aedeagus from lateral view; H. Paramere of aedeagus from lateral view; I, J. Spermatheca.
Head small; color blackish brown; eyes small. Antennae (Fig. 7A) short, gently clubbed; relative length of each antennal segment from first to 11th, 3.2: 1.95: 1.48: 1.18: 1.14: 1.00: 1.00: 1.11: 1.43: 1.64: 4.5.
Thorax.
Pronotum (Fig. 7B) subrectangular, transverse (PW/PL, 1.53–1.57), widest at posterior 1/3, postero-lateral angle distinctly acute, posterior margin distinctly sinuate, blackish brown, surface finely covered with shortened setae and punctures, polished and hardly reticulated. Elytra (Fig. 7B, C) distinctly widened posteriad entirely, posterior margins shallowly notched near lateral corners, blackish brown, surface finely covered with shortened setae and punctures, polished and hardly reticulated. Hind wings developed. Mesoventral process (Fig. 7D) very narrow, with indistinct medial carina, apex sharply pointed, reaching middle of mesocoxal cavities. Metaventral process hardly produced.
Abdomen elongate, narrowed posteriad; surface covered with very short setae and each posterior margin with long stout setae; slightly reticulated.
Male: 8th sternite (Fig. 7E) slightly emarginated at postero-median margin; median lobe of aedeagus (Fig. 7G) bulbous, length about 0.60 mm, apical lobe thick and almost straight, apex gently pointed in lateral view, apical valves broad and mitten-shaped, dorsal arms very short, basal part of copulatory piece large. Paramere (Fig. 7H) length about 0.68 mm; apical lobe of paramere long and narrow, length about 1/3 of whole paramere, slightly curved ventrally; four setae, normally arranged, velum normal.
Female: 8th sternite (Fig. 7F) slightly rounded at posterior margin; spermatheca (Fig. 7I, J) S-shaped, apex of basal part weakly swollen.
Variations.
In some individuals, the parameral apical lobe is irregularly sharpened apicad. The arrangement of the four setae varies slightly.
Measurements (in mm) and ratios.
Body parts (N = 10): BL ≈ 2.44–3.96; AL, 0.91–1.01; HW, 0.52–0.64; PL, 0.6–0.75; PW, 0.94–1.15; EL, 0.48–0.56; EW, 0.96–1.16; HTL, 0.6–0.72; PW/PL, 1.53–1.57; AL/PL, 1.34–1.51; HTL/PL, 0.96–1.03.
Differences between sexes: AL/PL (male, N = 5), 1.43–1.51; AL/PL (female, N = 5), 1.34–1.42.
Homoeusalaevigata Sharp, 1888. A. Distribution map; black star – the type locality (“Seba”); white circles – collection data examined in this paper; B. A walking adult (red arrow) in a foraging trail of Lasiusnipponensis on a trunk, Matsumoto-shi, Nagano-ken, Honshu; C–E. Snapped images from videos shot indoors; C raising abdomen to an ant; D. Later begging for food and succeeding in trophallaxis; E. Licking host ant’s foreleg; F. Another shot of trophallaxis (photographed by Takuto Hashizume); G. Living individual from Kai-shi, Yamanashi-ken (photographed by Taku Shimada); H. Clear image of a living adult from Nagano-ken.
Homoeusalaevigata can be observed in Lasiusnipponensis foraging trails on forest floors or at the base of trunks (Fig. 8B) from May to August. No individuals were collected using FIT.
This species appears to be more integrated into its host colony than other Homoeusa species. Trophallactic behavior with the host ant worker has been observed around nests and foraging trails (Maruyama et al. 2013). In addition, near a colony, TN observed them licking the workers’ legs and bodies as the worker ants groomed each other. In the indoor observations, they frequently raised the tip of their abdomen toward host ant workers (Fig. 8C), grooming (Fig. 8E), and displaying trophallaxis (Fig. 8D, F). Unexpectedly, they were also observed eating food by themselves indoors.
Remarks.
The presently known distribution of H.laevigata (Fig. 8A) is restricted to the east of Hida Mountains in central Honshu. TN examined the collection by Mr. K. Kinomura from some colonies of L.nipponensis in Takayama-shi, Gifu-ken, and surveyed a single colony of the ant in June in Motosu-shi, Gifu-ken. These surveys did not identify H.laevigata west of the Hida Mountains. Considering the absence of this species with Lasius species other than L.nipponensis, and their behavior toward host ant workers, this species could be a specialist for this ant species.
AnimaliaColeopteraStaphylinidaeDAAE202E-F1DF-5CEA-A714-ABFE50E7AF80HomoeusajaponicaSharp, 1874Figs 2B, E, 3C, 9A–L, 10A–H (Japanese name: Yamato-hirata-ariyadori)HomoeusajaponicaSharp, 1874: 5 (original description); Schülke and Smetana 2015; 682 (catalogue); Maruyama et al. 2013: 25 (distribution and bionomics mentioned).“Homoeusaacuminata”; Sharp 1888: 283 (recorded from “Miyanoshita” as H.acuminata, which is a misidentification). Type material.
Japan: Honshu: Aomori-ken • 2♂♂; Hyakuzawa-higashi, Iwakisan [40.629, 140.327], Hirosaki-shi; 25.VI.2023; TS. Nozaki leg. (KUM). Iwate-ken • 1 ex.; Gandô-ko, Morioka-shi; 9.VI.2019; N. Nakaya leg. LFcfF (IPMM) • 3 exs.; Takamatsu-kôen, Morioka-shi; 22.VII.2019; N. Nakaya leg. LFcfF (IPMM) • 1 ex.; Kitayama-sansakuro, Morioka-shi; 19.V.2019; N. Nakaya leg. LFcfF (IPMM) • 1 ex.; same locality; 5.V.2019; N. Nakaya leg. LFcfF (IPMM) • 1♂, 3 exs.; Kitayama, Morioka-shi; 3.V.2023; N. Nakaya leg. LFcfF (IPMM). Miyagi-ken • 1♀; Naruko-onsen, Osaki-shi; 14–17.VI.1999; M. Sano leg. LFO (KUM) • 1♂; Aoba-yama, Sendai-shi; 17.VII.2004; K. Mizota leg. LFN (KUM) • 2♀♀; Toriido-yama, Komono-chô; 2.VI.2012; N. Tsuji leg. (KUM). Akita-ken • 1♂; Tamagawa, Tazawako, Semboku-shi; 12–13.VI.1999; M. Sano leg. LFcfF (KUM). Fukushima-ken • 1♂, 2 exs.; Kashi Spa., Nishigo-mura; 16.VI.1998; M. Maruyama leg. LFcfF (KUM) • 1♀, 2 exs.; same locality; 17.VI.1998; M. Maruyama leg. LFcfF (KUM) • 1♂, 1 ex.; Yukiwari-bashi, Nishigo-mura; 29.VII.2000; T. Kobashi leg. (KUM) • 3 exs.; Mizuhiki, Tateiwa, Minamiaizu-machi; 12.VI.2004; H. Kamezawa leg. LFcfF (cKam). Ibaraki-ken • 1♂; Sadanami, Sekimoto-chô, Kitaibaraki-shi; 4.V.2022; Y. Komatsuzaki leg. (KUM) • 1♂; Oshô-yama, Kitaibaraki-shi; 24.IV.2022; S. Fuda leg. (KUM) • 1 ex.; Takeo-rindo (alt. 450 m), Hitachiota-shi; 3.V.2022; Y. Komatsuzaki leg. (KUM) • 1♂; Asahi-tôge, Tsuchiura-shi; 8.V.2022; Y. Komatsuzaki leg. (KUM) • 2 exs.; Nagai, Tsuchiura-shi; 27.IV.2022; Y. Komatsuzaki leg. (KUM). Tochigi-ken • 1♂, 1♀, 72 exs.; Ichikai-machi; 29.IV.–2.V.2002; S. Nagashima leg. LFcfF (KUM). Gunma-ken • 2♂♂, 2♀♀, 4 exs.; Nakanojo Forest Park, Nakanojo-machi; 8.VI.2001; T. Watanabe leg. (KUM) • 1 ex.; “4km NW Onishidashi Rock Gdn.”; “18–21.VII.80” [1980]; A. & Z. Smetana leg. (NMST, KUM, ex A. Smetana coll.) • 1 ex.; Sakurayama, Fujioka-shi; 3.V.1998; S. Arai leg. (KUM) • 1♀, 28 exs.; Sakurayama Park, Onishi, Fujioka-shi; 9.V.1998; S. Arai leg. LFS (KUM) • 1♂, 21 exs.; Mt. Sakurayama, Onishi, Fujioka-shi; 9.V.1998; K. Toyoda leg. LFS (KUM) • 6 exs.; same locality; 18.V.1998; K. Toyoda leg. LFS (KUM) • 5♂♂, 1♀, 18 exs.; same locality; 22.V.1999; Shiho Arai leg. LFS (KUM) • 5 exs.; Nageishi-tôge, Fujioka-shi; 5.VI.2001; T. Watanabe leg. (KUM). Saitama-ken • 3 exs.; Sugiyama Jôshi, Ranzan-machi; 29.IV.2005; K. Toyoda leg. (KUM) • 1 ex.; Mino-yama, Minano-machi; 15.VII.2000; K. Toyoda leg. (KUM) • 10 exs.; Shioyama, Ranzan-machi; 21.VI.1996; K. Toyoda leg. (KUM) • 1♂, 4 exs.; same locality; 8.VI.1997; K. Toyoda leg. (KUM) • 2 exs.; Mt. Shioyama, Ranzan-machi; 10.V.1998; K. Toyoda leg. LFcfF (KUM) • 1 ex.; same locality; 3.VII.1998; K. Toyoda leg. (KUM) • 2 exs.; Shiro-yama, Kamagata, Ranzan-machi; 17.VI.2000; K. Toyoda leg. (KUM) • 1 ex.; Near Toki-gawa, Ranzan-machi; 22.IV.1999; K. Toyoda leg. LFcfF (KUM) • 5 exs.; Toki-gawa, Ranzan-machi; 25.IV.1999; K. Toyoda leg. (KUM) • 2 exs.; same locality; 14.V.2000; K. Toyoda leg. (KUM) • 1 ex.; Shôgunsawa, Ranzan-machi; 21.IV.1999; K. Toyoda leg. (KUM) • 2 exs.; Shiroishi-tôge, Higashichichibu-mura; 9.V.1999; K. Toyoda leg. (KUM) • 3 exs.; same locality; 20.VI.1999; S. Arai leg. (KUM) • 2 exs.; Kuroishi Jinja, Kumai, Hatoyama-machi; 29.IV.2000; S. Arai leg. LFS (KUM) • 1♂, 1 ex.; Nr. Ôno Pass, Tokigawa-machi; 5.VIII.1998; K. Toyoda leg. LFcfF (KUM) • 1 ex.; Ushidatekubo (alt. 830 m) [35.9685, 139.1793], Tokigawa-machi; 21.V.2023; S.T. Inoue & N. Katsube leg. LFcfF (KUM) • 1 ex.; Hashidate, Chichibu-shi; 26.IV.1998; K. Toyoda leg. LFS (KUM) • same locality; 26.IV.1998; S. Arai leg. (KUM) • 1♂, 1 ex.; same locality; 17.VIII.1999; K. Toyoda leg. LFN (KUM) • 1♀, 5 exs.; same locality; 30.VII.2000; K. Toyoda leg. LFN (KUM) • 1 ex.; same locality; 7.VI.2002; K. Toyoda leg. (KUM) • 1 ex.; Tenjinsha, Kita-hirasawa, Hidaka-shi; 4.VI.1999; K. Toyoda leg. (KUM). Chiba-ken • 11 exs.; Azeta, Sakura-shi; 20.VI.1998; M. Maruyama leg. LFS (KUM) • 1♀, 4 exs.; same locality; 23–24.VI.1998; M. Maruyama leg. LFS (KUM) • 2 exs.; same locality; 20–26.VI.1998; M. Maruyama leg. LFS (KUM) • 2 exs.; same locality; 24.VI.1998; M. Sano leg. (KUM) • 3 exs.; Aoba, Chiba-shi, 24.VI.1998; M. Maruyama leg. LFS (KUM) • 6 exs.; Mt. Mifuneyama, Shôkô, Kimitsu-shi; 24.IV.2006; H. Ono leg. LFN (KUM) • 6 exs.; same locality; 7.V.2006; H. Ono leg. (KUM) • 1♀; Umegase, Daifuku-yama, Ichihara-shi, 6.V.1998; S. Naomi leg. (KUM) • 2 exs.; Shimin-nomori Yachô-no-mori, Toyooka, Futtsu-shi; 19.IV.2006; H. Ono leg. (KUM). Tokyo-to • 2 exs.; Kurosawa, Oume-shi; 29.IV.1998; U. Kurosu leg. (SPMN) • 1 ex.; Dokan-bori, Imperial Palace, Chiyoda-ku; 17.V.2000; T. Shimada leg. (NSMT) • 3 exs.; Mt.Takao, Hachiôji-shi; 1.V.1985; S. Kubota leg. (KUM) • 1 ex.; Mt. Takao (alt. 500 m), Hachiôji-shi; 1.VII.1998; M. Maruyama leg. LFS (KUM) • 3 exs.; same locality; 4.VII.1998; M. Maruyama leg. LFS (KUM) • 1 ex.; same locality; 1–4.VII.1998; M. Maruyama leg. LFS (KUM) • 1♂, 2♀♀, 20 exs.; same locality; 4.VI.2001; M. Maruyama leg. LFS (KUM, NHM) • 3 exs.; Mt.Takao (alt. 450 m), Hachiôji-shi; 4.VI.2001; M. Maruyama leg. LFS (NHM). Kanagawa-ken • 1♂, 1 ex.; Mt. Masukata, Kawasaki-shi; 15.VI.1996; K. Kawada leg. (KUM) • 5 exs.; Ikuta-ryokuchi, Kawasaki-shi; 13.IV.2002; K. Matsumoto leg. (KUM) • 4 exs.; Mikage, Tsukui, Sagamihara-shi; 18.IV.1976; R. Kiryu leg. (SCM) • 2 ex.; same locality; 23.IV.1977; R. Kiryu leg. (SCM) • 1ex.; same locality; 14.IV.1979; R. Kiryu leg. (SCM) • 1ex.; same locality; 31.V.1979; R. Kiryu leg. (SCM) • 2exs.; same locality; 9.VI.1979; R. Kiryu leg. (SCM) • 1 ex.; Nanzawa, Tsukui, Sagamihara-shi; 29.V.1976; R. Kiryu leg. (SCM) • 4 exs.; same locality; 14.V.1977; R. Kiryu leg. (SCM) • 2 exs.; same locality; 20.V.1977; R. Kiryu leg. (SCM) • 1 ex.; same locality; 22.IV.1979; R. Kiryu leg. (SCM) • 1 ex.; same locality; 24.V.1979; R. Kiryu leg. (SCM) • 1 ex.; Miyagase, Tsukui; 9.VII.1976; R. Kiryu leg. (SCM) • 12 exs.; Toya, Tsukui, Sagamihara-shi; 11.V.1976; R. Kiryu leg. (SCM) • 8 exs.; same locality; 27.IV.1976; R. Kiryu leg. (SCM) • 5 exs.; same locality; 29.IV.1977; R. Kiryu leg. (SCM) • 1 ex.; same locality; 17.IV.1979; R. Kiryu leg. (SCM) • 17 exs.; Kawasaki; 1.V.1985; S. Kubota leg. (KUM) • 2 exs.; “Trap (liver) St.1 Y.N.S”; Yokohama-shi; 10.V.1988; Y. Kominami leg. (SPMN) • 3 exs.; Niiharu-shiminno-mori, Yokohama-shi; 21.V.2001; T. Watanabe leg. LFO, LFS (KUM) • 1 ex.; Nonkendainomori, Enkaizan, Yokohama-shi; 3.V.1991; K. Kubo leg. (SPMN) • 1 ex.; Yakunimi-yama [35.35, 139.17], Hadano-shi; 26.VI.2014; O. Saitoh leg. LFcfF (KPMNH) • 4 exs.; Kawana, Fujisawa-shi; 14.V.2001; T. Watanabe leg. (KUM) • 1♂, 15 exs.; Jimmu-ji, Zushi-shi; 20.VI.2003; M. Maruyama leg. (KUM) • 1 ex.; Futagoyama, Zushi-shi; 15.IV.1991; H.Watarai leg. (SPMN) • 1 ex.; Kinugasa, Yokosuka-shi; 26–27.IV.1995; Y. Kaneko leg. (KUM) • 3 exs.; Miyanoshita, Hakone, Hakone-machi; 5.V.1987; Y. Hirano leg. (KUM) • 1 ex.; Hakone; 1.V.1974; Y. Hirano leg. (KUM) • 1 ex.; Miura Kurihama, Sagamihara-shi; 9.V.1979; R. Kiryu leg. (SCM). Yamanashi-ken • 1 ex.; Ashiyu-onsen, Ashiyu-mura; 23.V.2001; T. Watanabe leg. (KUM). Nagano-ken • 1♀, 1 ex.; Bôdaira, Shiga-kôgen (alt. 1,160 m) [36.7203, 138.4656], Yamanouchi-machi; 9.VII.2022; TS. Nozaki leg. LFM (KUM) • 1♂; Fujii, Satoyamabe, Matsumoto-shi; 7.VII.2022; TS. Nozaki leg. LFN (KUM). Gifu-ken • 2♂♂; Bijo Pass, Takayama-shi, 5.VIII.2003; K. Kinomura leg. (KUM) • 8 exs.; Ogamigo, Shôkawa (alt. 800 m), Takayama-shi; 5–6. VIII. 1998; M. Maruyama leg. LFS (KUM) • 1 ex.; Isshiki, Takayama-shi; 23.V.2004; K. Kinomura leg. LFN (KUM) • 1 ex.; Mt. Kentô, Takayama-shi; 6.VII.2003; K. Kinomura leg. (KUM) • 1♂; Neo-Mizudori, Motosu-shi; 4.VII.2022; TS. Nozaki leg. LFN (KUM) • 1 ex.; Miyachi [Gifu-ken?]; 29.IV.1980; Y. Ohta leg. (KUM) • 1 ex.; Yôrô Park, Yôrô-chô; 29.IV.2004; K. Kinomura leg. (KUM). Shizuoka-ken • 1 ex.; Kumazaka, Izu-shi; 30.V.2022; T. Tenma leg. (KUM). Aichi-ken • 1♀, 2 exs.; Jôkôji-kôen, Seto-shi; 16.IV.2023; T. Tenma leg. (KUM) • 1♂, 7 exs.; Magarida, Toyooka-chô, Gamagori-shi; 4.V.2024; T. Temma leg. LFcfF (KUM). Kyoto-fu • 1♀; Amagase Forest, Uji; 8.V.2013; T. Ito leg. (OMNH). Osaka-fu • 1♂; Mt. Myoken; 2.V.2015; T. Ito leg. (OMNH) • 1♀; same locality; 8.V.2012; T. Ito leg. (OMNH) • 1♂; Mino-o Park; 6.VI.2009; T. Ito leg. (OMNH). Nara-ken • 1♂; Yamato-Koriyama, Yata; 18.V.2009; T. Ito leg. (OMNH). Wakayama-ken • 2♂♂, 2♀♀, 3 exs.; Nishihara (alt. 180 m) [33.781, 135.413], Hidakagawa-chô; 11.VI.2023; TS. Nozaki leg. LFS (KUM). Tottori-ken • 1♂; Mt. Hôbutsu (alt. 420 m) [35.2271, 133.4561], Hino-chô; 17.VI.2024; TS. Nozaki leg. (KUM). Shimane-ken • 1♂, 3 exs.; Urahikimi, Masuda-shi, Masuda-shi; 6.VI.1998; S. Nomura leg. LFS (KUM). Okayama-ken • 2♂♂, 1♀, 5 exs.; Ono Shine, Kawakami, Ohara-chô, Mimasaka-shi; 5.V.2009; Y. Fujitani leg. LFS (KUM) • 1 ex.; same locality; 7.V.2009; Y. Fujitani leg. (KUM) • 1 ex.; same locality; 15.V.2009; Y. Fujitani leg. (KUM) • 1 ex.; same locality; 24.V.2009; Y. Fujitani leg. (KUM). Hiroshima-ken • 1♂, 3 exs.; Kakezu-yama, Higashiyawatahara (alt. 850–1,126 m), Kitahiroshima-chô; 9–18.V.2009; TA. (Tastuya) Nozaki & Y. Nozaki leg. FIT (KUM). Yamaguchi-ken • 1 ex.; Nishimagura, Kusunoki (alt. 100 m); Ube-shi; 30.V–1.VI.2000; T. Kishimoto leg. (KUM). Shikoku: Tokushima-ken • 1 ex.; Takashiro-yama, Naka-chô; 24.V.2007; H. Fujimoto leg. (KUM). Kagawa-ken • 1 ex.; Furodani, Miki-chô; 30.VII.2000; K. Izawa leg. LFcfF (KUM) • 1 ex.; Usa-jinja, Nagaona, Sanuki-shi; 31.V.2001; Maruyama et al. leg. LFS (KUM) • 1♂, 1 ex.; Fujio-Jinja, Nishi-uta-chô, Takamatsu-shi; 31.V.2001; Maruyama et al. leg. LFN (KUM) • 3 exs.; same locality; 1.VI.2001; Maruyama et al. leg. LFN (KUM) • 1 ex.; Ôtawa, Nagao, Sanuki-shi; 22.V.2000; F. Ito leg. LFM (KUM) • 1♂, same locality; 7.VI.2001; F. Ito leg. (KUM) • 2 exs.; Kamiyama, Miki-chô; 1.VI.2001; Maruyama et al. leg. LFS (KUM) • 13 exs.; Atago-yama, Kotohira-chô; 1.VI.2001; M. Maruyama leg. LFS (KUM) • 1♀, 7 exs.; Ôtaki-san, Shionoe-chô, Takamatsu-shi; 2.VI.2001; Maruyama et al. leg. (KUM) • 1 ex.; Daisen-zan, Kotonami-chô; 1.VI.2001; Maruyama et al. leg. LFM (KUM). Ehime-ken • 1 ex.; Higashino, Matsuyama-shi; 30.V.2015; Y. Hisasue leg. (KUM) • 3♀♀; same locality; 30.V.2015 (KUM) • same locality; 22.IV.2017; R. Koga leg. (EUMJ). Kochi-ken • 1♀; Ashizuri-misaki (alt. 120 m) [32.748, 133.0136], Tosashimizu-shi; 21.V.2024; TS. Nozaki leg. (KUM). Kyushu: Fukuoka-ken • 1 ex.; Mt. Inunaki, Miyawaka-shi; 22.V.1980; T. Gotô leg. (KUM) • 1 ex.; Mt. Tachibana; 6–9.V.1996; T. Ueno, Y. Higashiura & H. Goto leg. FIT (cSch) • 1 ex.; same locality; 10–14.V.1996; T. Ueno, Y. Higashiura & H. Goto leg. FIT (cSch) • 1♀; Takasubaru Highland, Mt Hikosan, Soeda-machi; 26.VI.2022; S.G. (Shugo) Inoue leg. LFcfF (KUM) • 2 exs.; Biol. Lab. Mt. Hikosan, Soeda-machi; 7.VI.1993; S. Nomura leg. LFcfF (KUM) • 2♂♂, 1♀; Biol. Lab. KU, Hikosan, (alt. 750 m) [33.48, 130.90], Soeda-machi; 22.V.2022; TS. Nozaki leg. LFcfF (KUM) • 2♂♂, 1♀; same locality; 16.V.2023; TS. Nozaki leg. LFcfF (KUM). Saga-ken • 1♀, 1 ex.; Mt. Kurokami-yama, Arita-chô; 28.IV.2019; M. Nishida leg. LFcfF (KUM) • 2 exs.; same locality; 15.V.2019; M. Nishida leg. (KUM) • 1♂; Mt. Kurokami-yama (alt. 400 m), Arita-chô; 9.V.2021; Y. Hisasue leg. LFcfF (KUM) • 1 ex.; Tosen-zan, Ureshino-shi; 29.IV.2018; M. Nishida leg. FIT (KUM). Nagasaki-ken • 1♂; Tanuki-no-o, Omura-shi; 5.V.2018; M. Nishida leg. (KUM). Oita-ken • 2♀♀; Oike, Kurodake, Yufu-shi; 17.VI.2021; TS. Nozaki leg. (KUM). Miyazaki-ken • 1♂; Ômoridake forest road (alt. 600 m) [32.0435, 131.1973], Aya-machi; 12.VI.2024; TS. Nozaki & T. Kinoda leg. LFS (KUM).
Diagnosis.
This species is distinguished from the other species of the genus by the following combination of characteristics: pronotal posterolateral angle around 90 degrees (Fig. 9C); elytra distinctly widened posteriad entirely (Fig. 9C); apical lobe of paramere long, length about half of whole paramere, curved ventrally, apex simply round (Fig. 9I, J). This species is quite similar to H.longicornis in its general appearance; however, the round apex of the parameral apical lobe can separate it.
Homoeusajaponica Sharp, 1874. A, B. Antenna; A. Male; B. Female; C. Pronotum and elytra; D. Zoomed view of elytron; E. Meso- and metaventrite; F, G. Posterior margin of 8th sternite; F. Male; G. Female; H. Median lobe of aedeagus from lateral view; I, J. Paramere of aedeagus from lateral view: I. Western population; J. Eastern population; K, L. Spermatheca.
Homoeusajaponica Sharp, 1874. A–D. Variations of aedeagi; A. Takamatsu-shi, Kagawa-ken, Shikoku; B. Motosu-chô, Gifu-ken, Honshu; C. Ichikai-machi, Tochigi-ken, Honshu; D. Nakanojo-shi, Gunma-ken; E. Distribution map; black star – the type locality (“Nagasaki”); white circles – collection data examined in this paper; black circle – dissected male from the western population; red circle – dissected male from the eastern population; F. A walking adult in a foraging trail of Lasiuscf.fliginosus on a fallen branch, Mt. Hikosan, Fukuoka-ken, Kyushu; G. Snapped images from videos shot indoors, raising abdomen to an ant; H. Clear image of living adult from Nagano-ken.
https://binary.pensoft.net/fig/1483280
Head large; color reddish brown to dark brown; eyes large. Antennae (Fig. 9A, B) long; relative length of each antennal segment from first to 11th, 2.32: 1.48: 1.19: 1.07: 1.05: 1.01: 1.00: 1.01: 1.25: 1.4: 2.88.
Thorax.
Pronotum (Fig. 9C) subrectangular, transverse (PW/PL, 1.59–1.71), widest near middle, postero-lateral angle around 90 degrees, posterior margin slightly sinuate, reddish yellow to reddish brown, surface finely covered with setae and punctures, gently polished and slightly reticulated. Elytra (Fig. 9C, D) distinctly widened posteriad entirely, posterior margins shallowly notched near lateral corners, reddish yellow to reddish brown, surface finely covered with setae and punctures; gently polished and weakly reticulated. Hind wings developed. Mesoventral process (Fig. 9E) very narrow, with weak medial carina, forming Y-shaped, apex sharply pointed, reaching posterior 1/3 of mesocoxal cavities. Metaventral process weakly produced.
Abdomen elongate, narrowed posteriad; surface covered with short setae and each posterior margin with long stout setae; finely reticulated.
Male: 8th sternite (Fig. 9F) rounded at posterior margin; median lobe of aedeagus (Fig. 9H) slender, length about 0.55 mm, apical lobe narrow and elongate, slightly curved dorsally, apex gently pointed in lateral view, apical valves simple and elongate, without dorsal arms, basal part of copulatory piece very small. Paramere (Fig. 9I, J) length about 0.65 mm; apical lobe of paramere very long, length about half of whole paramere, curved ventrally, slightly dilated apicad, apex simply round; four setae, a far longer than others, b located most apically, velum short and suboval.
Female: 8th sternite (Fig. 9G) truncated or slightly rounded at posterior margin; spermatheca (Fig. 9K, L) S-shaped, base of apical part not swollen, base largely hooklike.
Variations.
Geographical variations were found in the parameral apical lobe. The populations from Chugoku, Shikoku, and Kyushu had a less curved apical lobe, with a finely dentate dorsal margin (Figs 9I, 10A), whereas the population from the eastern part of Honshu had a more curved apical lobe with a smooth dorsal margin (Figs 9J, 10 B–D). The distribution of each population is shown in Fig. 10E.
Measurements (in mm) and ratios.
Body parts (N = 19): BL ≈ 2.14–3.27; AL, 0.81–1.03; HW, 0.51–0.66; PL, 0.48–0.63; PW, 0.78–1.03; EL, 0.42–0.51; EW, 0.85–1.02; HTL, 0.52–0.67; PW/PL, 1.59–1.71; AL/PL, 1.36–1.86; HTL/PL, 0.94–1.15.
Distribution.
Japan (Honshu, Shikoku, Kyushu) (Fig. 10E).
Symbiotic hosts.
Lasiusfuliginosus species group: L.cf.fuliginosus, L.morisitai, L.nipponensis, L.orientalis, L.spathepus.
Bionomics.
Homoeusajaponica can be observed in Lasiusfuliginosus species group foraging trails on the forest floor from April to August (Fig. 10F). Only a few individuals were collected using FIT (N = 7). They frequently raised the tip of their abdomen toward approaching host ant workers, both in the field and indoors (Fig. 10G).
Remarks.
According to the original description (Sharp 1874), the type locality was assumed to be Nagasaki City, Nagasaki Prefecture, Kyushu. This species was rarely collected from the trails of L.nipponensis and L.orientalis.
The differences in the parameres between the two populations were significant; however, no other differences were found. They may have been distributed separately because they were never collected from the same locality. We conclude that they can be reasonably treated as intraspecific populations. This species tends to occur at lower altitudes than H.longicornis does.
AnimaliaColeopteraStaphylinidae4B546179-050E-5C99-9F04-4986E90FD707HomoeusalongicornisSharp, 1888Figs 2C, F, 3D, 11A–K, 12A–F (Japanese name: Higenaga-hirata-ariyadori)HomoeusalongicornisSharp, 1888: 283 (original description); Schülke and Smetana 2015; 682 (catalogue); Maruyama et al. 2013: 25 (distribution and bionomics mentioned).Type material.
Japan: Hokkaido • 2 exs.; Hebinuma, Teshio-gawa, Teshio-chô; 9.VII.1992; S. Hori leg. (KUM) • 2♂♂; Mukôengaru, Engaru-chô; 25.V.2000; Y. Kida leg. (KUM) • 3 exs.; Kanayama, Makoi, Shari-chô; 24.VI.2002; Y. Kida leg. (KUM) • 3 exs.; Taihei, Maruseppu, Engaru-chô; 28.V.2000; Y. Kida leg. LFcfF (KUM) • 22 exs.; same locality; 29–31.V.2000; Y. Kida leg. LFcfF (KUM) • 11 exs.; same locality; 2–3.VI.2000; Y. Kida leg. LFcfF (KUM) • 1 ex.; same locality; 13.VI.2000; Y. Kida leg. (KUM) • 6♂♂, 5♀♀, 288 exs.; same locality; 16–17.VI.2000; Y. Kida leg. LFcfF (KUM) • 1♂, 7 exs.; same locality; 19–21.VIII.2000; Y. Kida leg. LFcfF (KUM) • 2♂♂, 1♀, 17 exs.; same locality; 25.VIII.2000; Y. Kida leg. LFcfF (KUM) • 1 ex.; Memanbetsu, Ôzora-chô; 7.VIII.2018; Y. Yoshimura leg. LFcfF (KUM) • 1 ex.; Kashiwa-gaoka-kôen, Bihoro-chô, 23.VI.2000; Y. Yamaga leg. (KUM) • 1 ex.; Mitomi-shizenkôen, Bihoro-chô; 13.VI.2000; Y. Yamaga leg. (KUM) • 2 exs.; Attoko, Nemuro-shi; 30.VI.1996; Y. Hirama leg. (KUM) • 5 exs.; Ôsawaguchi, Nopporo-shinrin-kôen, Ebetsu-shi; 2.VI.1999; M. Maruyama leg. (KUM) • 26 exs.; Ôsawaguchi, Nopporo-shizenkôen, Ebetsu-shi; 16–19.VI.2001; S. Hori leg. (KUM) • 2 exs.; Mt. Maruyama, Sapporo-shi; 6.VI.1998; M. Maruyama leg. (KUM) • 2 exs.; Tomanbetsu, Nopporo, Ebetsu-shi; 29.V.2002; M. Maruyama leg. LFcfF (KUM) • 2 exs.; Shibumbersu, Nopporo-shinrin-kôen, Ebetsu-shi; 11.V.2000; M. Maruyama leg. LFcfF (KUM) • 1 ex.; Mt. Moiwa, Sapporo-shi, 16.VI.1983; Y. Hirano leg. (KUM) • 10 exs.; Hitsujigaoka, Sapporo-shi; 18.V.2000; M. Maruyama leg. LFS (KUM) • 24 exs.; Kannon-zawa, Sapporo-shi; 1.VI.2002; M. Maruyama leg. LFcfF (KUM) • 1♂, 2♀♀, 24 exs.; same locality; 31.VI.2002; M. Maruyama leg. LFcfF (KUM) • 2 exs.; Hyakumatsuzawa, Sapporo-shi; 8.VI.1998; M. Maruyama leg. LFcfF (KUM) • 4 exs.; Hakken-zan, Sapporo-shi; 31.V.2002; M. Maruyama leg. LFcfF & LU (KUM) • 3 exs.; same locality; 1.VI.2002; M. Maruyama leg. LFcfF & LU (KUM) • 1 ex.; Yûtoku, Ôtaki-mura, Date-shi; 24.VIII.2001; M. Maruyama leg. (KUM). Honshu: Aomori-ken • 1 ex.; Yokonagare-tôge (alt. 300 m) [41.264, 141.314], Higashidori-mura; 26.VI.2023; TS. Nozaki leg. LFcfF (KUM) • 1♂, 1♀, 1 ex.; Kuromori (alt. 280 m) [40.677, 140.191], Ajigasawa-machi; 24.VI.2023; TS. Nozaki leg. LFcfF (KUM) • 1♀; Yunosawa, Tokiwano (alt. 490 m) [40.633, 140.268], Hirosaki-shi; 25.VI.2023; TS. Nozaki leg. LFcfF (KUM). Miyagi-ken • 1♀; Toriido-yama, Komono-chô; 2.VI.2012; N. Tsuji leg. (KUM). Yamagata-ken • 1♂, 1 ex.; Senjuin, Yamadera (alt. 300–320 m) [38.319, 140.448], Yamagata-shi; 15.VII.2024; K. Mizota leg. LFcfF (KUM). Fukushima-ken • 4 exs.; Kashi Spa., Nishigo-mura; 16.VI.1998; M. Maruyama leg. LFcfF (KUM) • 1♀, 3 exs.; same locality; 17.VI.1998; M. Maruyama leg. LFcfF (KUM) • 1 ex.; Yukiwari-bashi, Nishigo-mura; 29.VII.2000; M. Maruyama leg. (KUM). Ibaraki-ken • 1 ex.; Sadanami, Sekimoto-chô, Kitaibaraki-shi; 4.V.2022; Y. Komatsuzaki leg. (KUM). Gunma-ken • 1 ex.; Tanigawa Spa, Minakami-chô; 7.VI.2001; T. Watanabe leg. (KUM) • 1 ex.; Near Shima, Nakanojo-machi; 12.VI.1986; T. Katsumoto leg. (SCM) • 2♂♂, 1♀, 4 exs.; Nakanojo Forest Park, Nakanojo-machi; 8.VI.2001; T. Watanabe leg. (KUM) • 10 exs.; Sakurayama Park, Onishi, Fujioka-shi; 9.V.1998; Shiho Arai leg. LFS (KUM) • 4 exs.; Mt. Sakurayama, Onishi, Fujioka-shi; 9.V.1998; K. Toyoda leg. LFS (KUM) • 3 exs.; same locality; 18.V.1998; K. Toyoda leg. LFS (KUM) • 2♂♂, 3♀♀, 3 exs.; same locality; 22.V.1999; Shiho Arai leg. LFS (KUM) • 1 ex.; Shiozawa-toge, Fujioka-shi, 6.IX.2001; T. Watanabe leg. (KUM). Saitama-ken • 1 ex.; Mt. Sakurayama, Onishi; 2.V.2009; K. Arai leg. (KUM) • 2 exs.; Mt. Kamafuse yama, Fu-uppu (alt. 570 m), Yorii-machi; 22.IV.2006; K. Arai leg. LFcfF (KUM) • 1 ex.; Chichibu-kôgen, Higashichichibu-mura; 3.VII.1999; K. Toyoda leg. (KUM) • 6 exs.; Kasayama Sancho, Koshigoe, Ogawa-machi; 30.IV.2005; K. Arai leg. LFS (KUM) • 2 exs.; Karibazaka Pass [35.9683, 139.1816], Tokigawa-machi; 24.V.2022; TS. Nozaki leg. LFcfF (KUM) • 2 exs.; Hashidate, Chichibu-shi; 26.IV.1998; K. Toyoda leg. LFS (KUM) • 1 ex.; same locality; 26.IV.1998; S. Arai leg. (KUM) • 3 exs.; same locality; 7.VI.2002; K. Toyoda leg. LFM (KUM) • 1 ex.; Koakazawa, Irikawa, Mt. Hakutai-san, Ootaki (alt. 1,100 m), Chichibu-shi; 7–8.VI.2008; K. Arai leg. (KUM). Tokyo-to • 4 exs.; Mt.Takao, Hachiôji-shi; 1.V.1985; S. Kubota leg. (KUM) • 2 exs.; Mt.Takaozan, Hachiôji-shi; 26.IV.1986; A. Izumi leg. LFS (KUM) • 2 exs.; Mt. Takao, Hachiôji-shi; 1.VII.1998; M. Maruyama leg. LFS (KUM) • 1 ex.; same locality; 4.VII.1998; M. Maruyama leg. LFS (KUM) • 1 ex.; Mt. Takao (alt. 500 m), Hachiôji-shi; 1–4.VII.1998; M. Maruyama leg. (KUM) • 1♂, 1♀, 12 exs.; Mt. Takao (alt. 450 m), Hachiôji-shi; 4.VI.2001; M. Maruyama leg. (KUM) • 1♂, 1 ex.; same locality, Hachiôji-shi; 4.VI.2001; M. Maruyama leg. LFS (NHM). Kanagawa-ken • 2 exs.; Hokizawa, Nishi-tanzawa; 25–26.VI.1983; Y. Hirano leg. (KUM) • 1 ex.; Minami-Ashigara-shi; 11.II.1975; Y. Hirano leg. (KUM) • 2 exs.; Mt. Daiyûzan, Minami-Ashigara-shi; 28.VI.1987; A. Izumi leg. LFcfF (KUM) • 1 ex.; Daiyuzan, Hakone; 26.V.1986; Y. Shibata leg. (KUM) • 1 ex.; Daiyuzan, Ashigara; 21.V.1989; Y. Shibata leg. (KUM) • 2 exs.; Hakone; 4.V.1987; M. Tao leg. (KUM). Niigata-ken • 1 ex.; Ochinomizu, Tokamachi-shi; 19.IV.1998; T. Kishimoto leg. LFcfF (KUM) • 1 ex.; Foot of Mt. Uedafuji, Yuzawa-machi; 18.IV.1998; H. Yoshitomi leg. (KUM) • 1 ex.; Yuzawa-machi; 20–22.VI.2002; S. Nagashima leg. LFcfF (KUM). Yamanashi-ken • 1♂; Gozaishi-kôsen (alt. 900 m), Nirasaki-shi; 25.VII.2002; S. Nomura leg. LFN (KUM) • 3 exs.; Ashiyu-onsen, Ashiyu-mura; 23.V.2001; T. Watanabe leg. (KUM) • 1 ex.; same locality; 24.V.2001; T. Watanabe leg. (KUM). Nagano-ken • 1 ex.; Midarebashi, Chikuhoku-mura; 21.VII.1999; T. Watanabe leg. (KUM) • 1♂, 1 ex.; Ôkubo, Komoro-shi; 29–30.IV.2001; H. Kamezawa leg. LFcfF (cKam). Gifu-ken • 2♂♂; Bijo Pass, Takayama-shi; 5.VIII.2003; K. Kinomura leg. (KUM) • 1♂, 1 ex.; Hirugano Bunsuirei Park, Gujo-shi; 10.VI.2013; K. Kinomura leg. (KUM) • 1♂; Mt. Kentô, Takayama-shi; 6.VII.2003; K. Kinomura leg. (KUM) • 2♂♂; Yôrô Park, Yôrô-chô; 29.IV.2004; K. Kinomura leg. (KUM). Shizuoka-ken • 2 exs.; Utsuno, Fujinomiya; 30.V.2000; T. Watanabe leg. Fish feed Bait, pinned with a Phidole ant det. by K. Matuura (KUM). Aichi-ken • 1♀; Jôkôji-kôen, Seto-shi; 16.IV.2023; T. Tenma leg. (KUM). Kyoto-fu • 1♂, 1 ex.; Tenno-zan, Oyamazaki-chô; 16.IV.2008; T. Ito leg. (OMNH) • 2 exs.; same locality; 31.V.2008; T. Ito leg. (OMNH) • 1♀; Amagase Forest, Uji-shi; 8.V.2013; T. Ito leg. (OMNH) • 1 ex.; Otokoyama, Yawata-shi; 11.V.2014; T. Ito leg. (OMNH) • 1♂; same locality; 14.VI.2008; T. Ito leg. (OMNH). Osaka-fu • 1♂; Mt. Mikusa, Nose-chô; 21.VI.2008; T. Ito leg. (OMNH) • 1♂; Mino-o Park, Mino-shi; 28.V.2008; T. Ito leg. (OMNH). Hyogo-ken • 2♂♂, 1♀, 1 ex.; Dojo, Kobe-shi; 13.IV.2009; T. Ito leg. (OMNH). Nara-ken • 1♀; Yamato-Koriyama, Yata; 9.VII.2009; T. Ito leg. (OMNH) • 1♂; same locality; 18.V.2009; T. Ito leg. (OMNH). Wakayama-ken • 1♂; Kimitoge Pass, Hashimoto-shi; 1.VI.2009; T. Ito leg. (OMNH) • 1♂; same locality; 27.IV.2014; T. Ito leg. (OMNH). Tottori-ken • 1 ex.; Mt. Daisen, Daisen-chô; 3–5.VI.1980; S. Naomi leg. (KUM). Shimane-ken • 1♂; Urahikimi, Masuda-shi, Masuda-shi; 6.VI.1998; S. Nomura leg. LFS (KUM). Hiroshima-ken • 1♂; Mt. Iwahi (alt. 1,110 m) [35.0712, 133.2192], Shobara-shi; 16.VI.2024; TS. Nozaki leg. LFcfF (KUM). Shikoku: Tokushima-ken • 2 exs.; Takashiro-yama, Naka-chô; 24.V.2007; H. Fujimoto leg. LFS (KUM). Kagawa-ken • 1 ex.; Ôtawa, Nagao, Sanuki-shi; 22.V.2000; F. Ito leg. (KUM) • 2 exs.; Daisen-zan, Kotonami-chô; 1.VI.2001; M. Maruyama et al. leg. LFN (KUM) • 1 ex.; same locality; 3.V.2004; H. Fujimoto leg. LFcfF (KUM). Ehime-ken • 1♂, 1♀; Mt. Ishiduchi, Saijo-shi; 29.VI.2014; Y. Hisasue leg. (KUM). Kochi-ken • 1♂, 1♀; Hokigamine (alt. 500 m) [33.6719, 133.6846], Kami-shi; 11.V.2023; TS. Nozaki leg. LFS (KUM).
Diagnosis.
This species is distinguished from the other species of the genus by the following combination of characteristics: pronotal posterolateral angle around 90 degrees (Fig. 11C); elytra distinctly widened entirely posteriad (Fig. 11C, D); apical lobe of paramere very long, length over half of whole paramere, curved ventrally, apex blade-shaped (Fig. 11I). This species is quite similar to H.japonica in its general appearance but can be separated by the blade-like apex of its parameral apical lobe.
Homoeusalongicornis Sharp, 1888. A, B. Antenna; A. Male; B. Female; C. Pronotum and elytra; D. Zoomed view of elytron; E. Meso- and metaventrite; F, G. Posterior margin of 8th sternite; F. Male; G. Female; H. Median lobe of aedeagus from lateral view; I. Paramere of aedeagus from lateral view; J, K. Spermatheca.
Homoeusalongicornis Sharp, 1888. A–C. Variations of aedeagi; A. Mt. Ishizuchi-san, Ehime-ken, Shikoku; B. Maruseppu-chô, Hokkaido; C. Nakanojo-shi, Gunma-ken; D. Distribution map; black star – the type locality (“Sapporo”); white circles – collection data examined in this paper; E. A walking adult in a foraging trail of Lasiuscf.fuliginous on a fallen branch, Iimori-toge, Saitama-ken, Honshu; F. Clear image of living adult from Aomori-ken.
https://binary.pensoft.net/fig/1483282
Head large; color reddish brown to dark brown; eyes small. Antennae (Fig. 11A, B) very long.
Thorax.
Pronotum (Fig. 11C) subrectangular, transverse (PW/PL, 1.53–1.64), widest anterior 1/3, postero-lateral angle around 90 degrees, posterior margin slightly sinuate, reddish yellow to reddish brown, surface finely covered with setae and punctures, gently polished and slightly reticulated. Elytra (Fig. 11C, D) distinctly widened posteriad entirely, posterior margins shallowly notched near lateral corners, reddish yellow to reddish brown, surface finely covered with setae and punctures; gently polished and weakly reticulated. Hind wings developed. Mesoventral process (Fig. 11E) very narrow, with weak medial carina, forming Y-shaped, apex sharply pointed, reaching posterior 1/3 of mesocoxal cavities. Metaventral process weakly produced.
Abdomen elongate, narrowed posteriad; surface covered with short setae and each posterior margin with long stout setae; finely reticulated.
Male: Relative length of each antennal segment from first to 11th, 1.66: 1.13: 1.16: 1.07: 1.00: 1.04: 1.00: 1.06: 1.01: 1.13: 2.25. 8th sternite (Fig. 11F) weakly rounded at posterior margin; median lobe of aedeagus (Fig. 11H) slender, length about 0.63 mm, apical lobe elongated, ventral side slightly humped at middle, apex gently pointed in lateral view, apical valves simple and very long, without dorsal arms, basal part of the copulatory piece very small. Paramere (Fig. 11I) length about 0.79 mm; apical lobe of paramere extremely long, length over half of whole paramere, curved ventrally, dilated apicad, apex blade-shaped; four setae, a far longer than others, b located most apically, velum elongate, broad and produced apically.
Female: Relative length of each antennal segment from first to 11th, 2.37: 1.57: 1.29: 1.09: 1.06: 1.00: 1.06: 1.08: 1.17: 1.40: 2.88. 8th sternite (Fig. 11G) truncated or slightly rounded at posterior margin; spermatheca (Fig. 11J, K) S-shaped, apex of basal part not swollen, base largely hooklike.
Variation.
Apical lobe of aedeagal median lobe varies on the degree of dorsally curve, intension of middle hump ventral side, and depth of basal concave (Fig. 12A–C) independently of geographical locations.
Measurements (in mm) and ratios.
Body parts (N = 12): BL ≈ 2.58–3.54; AL, 0.98–1.3; HW, 0.59–0.7; PL, 0.59–0.72; PW, 0.97–1.13; EL, 0.5–0.59; EW, 0.94–1.13; HTL, 0.65–0.8; PW/PL, 1.53–1.64; AL/PL, 1.5–1.91; HTL/PL, 0.98–1.13.
Differences between sexes: AL/PL (male, N = 5), 1.82–1.91; AL/PL (female, N = 7), 1.5–1.65; HTL/PL (male, N = 5), 1.05–1.13; HTL/PL (female, N = 7), 0.98–1.04.
Distribution.
Japan (Hokkaido, Honshu, Shikoku) (Fig. 12D).
Symbiotic hosts.
Lasiusfuliginosus species group: L.cf.fuliginosus, L.morisitai, L.nipponensis, L.orientalis, L.spathepus.
Bionomics.
Homoeusalongicornis can be observed in Lasiusfuliginosus species group foraging trails on the forest floor from April to August (Fig. 12E). To the best of our knowledge, no individual was collected using FIT. The beetles were observed to be frequently raising the tip of their abdomen when approaching the host ant workers in the field and indoors.
Remarks.
This species is rarely collected from the trails of L.nipponensis and L.orientalis. This species is very similar to H.japonica in terms of its habitus (Fig. 12F) and bionomics. H.longicornis tends to occur at higher altitudes than that of H.japonica. However, both species frequently co-occur at moderate altitudes in Honshu and Shikoku, even within the same colony of host ants. Precisely distinguishing between the two species is challenging without examining male genitalia. The pronotum length can be helpful; that of H.longicornis is usually longer than 0.65 mm, whereas that of H.japonica is shorter than 0.65 mm, but some exceptions remain in both species.
AnimaliaColeopteraStaphylinidaeB8B9331D-8F9F-5577-8EA3-0E260A3174A6HomoeusaprolongataSawada, 1970Figs 3E, 13A–I, 14A–D (Japanese name: Hirata-ariyadori)HomoeusaprolongataSawada, 1970b: 57, fig. 14 (original description); Schülke and Smetana 2015; 682 (catalogue); Maruyama et al. 2013: 26 (distribution and bionomics mentioned).Type material.
Not examined.
Additional material examined.
Japan: Hokkaido • 2 exs.; Near Hime-numa, Oshidomariwannai (alt. 130 m), Rishiri-chô; 5.VI.2024; T. Yamauchi leg. (OUAVM) • 1 ex.; “Horokanai Butokamabetsu Riv” (alt. 300 m); 3.VIII.1991; A. Smetana leg. (NMST, ex A. Smetana coll.) • 1 ex.; Kanayama, Makoi, Shari-chô; 24.VI.2002; Y. Kida leg. (KUM) • 1♂, 1 ex.; Teine-yama [43.0836, 141.2024], Sapporo-shi; 23.V.2020; Y. Tasaku leg. (KUM) • 1♂; Ôsawaguchi, Nopporo-shizenkôen, Ebetsu-shi; 16–19.VI.2001; S. Hori leg. (KUM) • 2 exs.; Kannon-zawa, Sapporo-shi; 19.V.2021; Y. Tasaku leg. (KUM) • 2 exs.; Hakken-zan, Sapporo-shi; 1.VI.2002; M. Maruyama leg. (KUM) • 1♀; Mt. Kariba, Shiribeshi; 12.VI.1986; S. Nomura leg. (KUM). Honshu: Aomori-ken • 1 ex.; Iwaki river riverbed, Kawazura (alt. 10 m) [40.694, 140.455], Itayanagi-machi; 28.VI.2023; TS. Nozaki leg. LNS (KUM). Iwate-ken • 1♀, 1 ex.; Kitayama, Morioka-shi; 23.IV–3.V.2024; N. Nakaya leg. FIT (IPMM) • 1 ex.; Mt. Takabora, Kamiyonai, Morioka-shi; 21.IV–3.V.2024; N. Nakaya leg. FIT (IPMM). Akita-ken • 1 ex.; Kawara-bo, Mt. Hachimine, Hanamaki-shi; 22–24.VI.1980; S. Naomi leg. (KUM). Fukushima-ken • 1 ex.; Zenjin, Mt. Chokai, Yurihonjo-shi; 19–20.VI.1980; S. Naomi leg. (KUM) • 1 ex.; Yokomuki, Mt. Adatara, Inawashiro-machi; 10.VII.1985; S. Nomura leg. (KUM) • 1 ex.; Kozodaira, Hinoemata-mura; 26.VII.1996; S. Naomi leg. (KUM) • 2 exs.; Nanairi, Hinoemata-mura; 24.VII.1990; T. Kishimoto leg. (KUM). Tochigi-ken • 1 ex.; Mt. Nasu; 3.VI.1994; S. Naomi leg. (KUM) • 2 exs.; Chuzenji, Nikko-shi; 28–30.VI.1982; S. Naomi leg. (KUM) • 1 ex.; same locality; 24.VII.1985; S. Nomura leg. (KUM) • 1 ex.; “Nikko N.P. Lake Chuzenjiko” (alt. 1,280 m); “14.VII.80” [1980]; A. & Z. Smetana leg. (NMST, ex A. Smetana coll.) • 1 ex.; “Nikko N.P. Senjugahara” (alt. 1400 m); “15.VII.80” [1980]; A. & Z. Smetana leg. (KUM, ex A. Smetana coll.) • 1 ex.; Nagaishi Forest Road, Ashikaga-shi; 27.V.1990; H. Ohkawa leg. (KUM) • 1♂; Watarase-yûsuichi, Fujioka-machi; 16.IV.2000; H. Ôkawa leg. (KUM). Gunma-ken • 1 ex.; Mikuni-tôge, Minakami-machi; 27.VI.1997; S. Naomi leg. (KUM) • 1 ex.; Hôshi-onsen, Minakami-machi; 26.VI.1997; S. Naomi leg. (KUM) • 1 ex.; Amemi-rindou, Minakami-machi; 4.V.1998; Shiho Arai leg. (KUM) • 1♂, 1 ex.; Sakurayama, Fujioka-shi; 9.V.1998; Shiho Arai leg. (KUM) • 1 ex.; same locality; 22.V.1999; K. Toyoda leg. LNH (KUM) • 1♀, 3 exs.; same locality; 22.V.1999; Shiho Arai leg. LNH (KUM) • 1 ex.; same locality; 27.V.2000; Shiho Arai leg. LNH (KUM). Saitama-ken • 1 ex.; Mt. Jômine-san, Minano-machi; 29.V.1999; Shiho Arai leg. LNH (KUM) • 1 ex.; Chichibu-kôgen, Higashichichibu-mura; 5.V.2000; Shiho Arai leg. (KUM) • 1 ex.; Sugaya, Ranzan-machi; 14.VI.1994; K. Toyoda leg. LNH (KUM) • 1 ex.; same locality; 16.VI.1994; K. Toyoda leg. (KUM) • 1 ex.; Iwadono, Higashimatsuyama-shi; 3.V.2005; K. Toyoda leg. LNJ (KUM) • 1 ex.; Near Tsumasaka-Toge, Hanno-shi; 20.VI.1998; K. Toyoda leg. (KUM) • 1♂; Kawaura-keikoku (alt. 600 m), Chichibu-shi; 20.VI.1998; Shiho Arai leg. (KUM) • 1♀; same locality; 27.VI.1998; Shiho Arai leg. (KUM) • 1 ex.; Kaminaguri, Hanno-shi; 23.V.1998; Shiho Arai leg. LNH (KUM) • 1 ex.; Sumiyairi-rindô, Hanno-shi; 3.VI.2000; Shiho Arai leg. LNH (KUM). Chiba-ken • 2 exs.; Ashida (alt. 10 m), Narita-shi; 17–25.VII.2014; R Nakamura leg. FIT (KUM) • 11 exs.; Okuno, Ichihara-shi; 12–14.VII.2000; S. Hatsushiba & T. Shimada leg. (KUM) • 1 ex.; same locality; 16–18.V.2001; S. Hatsushiba & T. Shimada leg. (KUM) • 1 ex.; same locality; 12–14.V.2001; S. Hatsushiba & T. Shimada leg. (KUM) • 1 ex.; Mt. Gundari, Ichinomiya-machi; 12.IV.1997; S. Nomura leg. (KUM) • 1 ex.; Umegase, Daifuku-yama, Ichihara-shi; 6.V.1998; S. Naomi leg. (KUM) • 1 ex.; Amatsu (alt. 70 m) [35.1406, 140.1512], Kamogawa-shi; 3.V.2016; S. Sejima leg. Litter (KUM). Tokyo-to • 1 ex.; Ônita, Ome-shi; 20.V.1991; T. Kishimoto leg. (KUM) • 1 ex.; Oyamada-chô, Machida-shi; 19.V.1992; T. Kishimoto leg. (KUM) • 1 ex.; Machida-shi; 28.V.1981; T. Niizato leg. (KUM). Kanagawa-ken • 3 exs.; Nanzawa, Tsukui, Sagamihara-shi; 6.V.1977; R. Kiryu leg. (SCM) • 1 ex.; Miyagase, Aikô; 19.IV.1977; R. Kiryu leg. (SCM) • 2 exs.; Kozukue, Yokohama-shi; 21.IV.1994; H. Sato leg. (KUM) • 1♂; Niiharutyô、Midori-ku [35.50, 139.51], Yokohama-shi; 25.IV.2012; O. Saitoh leg. (KPMNH) • 3 exs.; Trap St.1.Park / “Y.N.S”, Yokohama-shi; 8.VI.1988; Y. Kominami leg. (SPMN) • 1 ex.; Yakunimi-yama [35.35, 139.17], Hadano-shi; 27.VI.2014; O. Saitoh leg. (KPMNH) • 1 ex.; Kinugasa, Yokosuka-shi; 26–27.IV.1995; S. Tsuboyama leg. (KUM). Niigata-ken • 1♂; Kita-ikari (alt. 760 m) [38.1500, 138.4049], Sado-shi; 18.VI.2023; TS. Nozaki leg. (KUM) • 3 exs.; Mt. Tadara-mine, Ryotsu (alt. 810 m) [38.13, 138.38]; Sado-shi; 11.VI.2012; M. Yoshida leg. (KUM) • 2 exs.; Yokoyama, Sado-shi; 24–25.V.1995; T. Kishimoto leg. (KUM) • 1 ex.; Kaikake-onsen, Yuzawa-machi; 23.VI.1996; K. Haga leg. Leaf litter in Beech forest (KUM) • 1 ex.; Sasagamine, Myoko-shi; 14–15.VI.1980; S. Naomi leg. (KUM) • 1 ex.; Suginosawa (alt. 950 m) [36.8519, 138.1399], Myoko-shi; 3.VI.2018; S. Sejima leg. Litter (KUM). Fukui-ken • 1 ex.; Mt. Houonji-san, Katsuyama-shi; 31.V.1989; Kouichi Matsumoto leg. (KUM) • 1 ex.; Mt. Gongen, Echizen-shi; 22.V.1981; H. Sasaji leg. (KUM). Yamanashi-ken • 1♀; Daibosatsu-rei [35.73, 138.82], Koshu-shi; 9.VI.2019; O. Saitoh leg. (KPMNH) • 1 ex.; Ryomata-goya, Noro-gawa riv., Minami-alps-shi; 3.VIII.1996; K. Haga leg. Fallen branch (KUM) • 5♂♂, 1♀, 2 exs.; Karumizu-rindo (alt. 1600 m), Narusawa-mura; 22–29.VI.2011; T. Watanabe leg. FIT (KUM) • 1 ex.; same locality; 29.VI–6.VII.2011; T. Watanabe leg. FIT (KUM) • 1 ex.; same locality; 27.VI–4.VII.2012; T. Watanabe leg. FIT (KUM) • 1 ex.; same locality; 25.VII–1.VIII.2012; T. Watanabe leg. FIT (KUM) • 2 exs.; Subashiri-guchi, Fujisan (alt. 1,400 m), Oyama-chô; 15–20.V.2011; T. Watanabe leg. FIT (KUM) • 1 ex.; Subashiri, Fujisan 1-gome (alt. 1,400 m), Oyama-chô; 20–26.V.2011; T. Watanabe leg. FIT (KUM). Nagano-ken • 2 exs.; Shiga-kôgen (alt. 1,380 m) [36.728, 138.478], Yamanouchi-machi; 9.VII.2022; TS. Nozaki leg. Litter (KUM) • 1 ex.; same locality; 9.VII.2022; TS. Nozaki leg. LNH (KUM) • 1♂; Mizunashiike, Shiga-kôgen, Yamanouchi-machi; 9.VII.2022; TS. Nozaki leg. (KUM) • 1 ex.; Satoyamabe, Matsumoto-shi; 4.VI.2009; T. Komatsu leg. LNJ (KUM) • 1♂; Tobira, Matsumoto-shi; 5.VI.2011; M. Maruyama et al. leg. (KUM) • 1♀; Kohigashi, Chino-shi; 19.VI.2011; M. Maruyama et al. leg. (KUM) • 1♂; Kannon-daira, Yatsuga-take; 11.VII.2000; H. Hoshina leg. Beating (KUM). Shizuoka-ken • 1 ex.; Subashiri-guchi, Fujisan (alt. 1,400 m), Oyama-chô; 15–22.VI.2011; T. Watanabe leg. FIT (KUM) • 2 exs.; Hiekawa, Izu-shi; 2.VI.1983; T. Tahira leg. (KUM). Kyoto-fu • 1 ex.; Mt. Yôrô-san, Maizuru-shi; 25–26.V.2000; K. Mizuno leg. (KUM). Hyogo-ken • 1 ex.; Mt. Hyonosen; 5.VI.1984; S. Nomura leg. (KUM) • 1 ex.; Mt. Mimuro-yama; 7.VI.1997; H. Hoshina leg. (KUM). Nara-ken • 1 ex.; Nara; “11.VIII.80” [1980]; A. & Z. Smetana leg. (KUM, ex A. Smetana coll.) • 1 ex.; Nishitani, Yoshino-chô; 18–19.V.1995; Y. Nakahara leg. Bait trap (KUM) • 2 exs.; Mt. Nehan-dake (alt. 1,140 m), Shimokitayama-mura; 27.VI.1998; T. Kishimoto leg. (KUM). Wakayama-ken • 1 ex.; Hirai, Kozagawa-chô; 15.VIII.1999; M. Maruyama leg. LNJ (KUM) • 1 ex.; same locality; 16.VII.1999; M. Maruyama leg. LNN (KUM). Tottori-ken • 1 ex.; Hokidaisen, Daisen-chô; 3.VI.1980; S. Naomi leg. (KUM) • 3 exs.; Mt. Daisen, Daisen-chô; 3–5.VI.1980; S. Naomi leg. (KUM) • 2 exs.; Ônarubara-kôgen (alt. 770 m), Kôfu-chô; 18–24.V.2008; A. Watanabe leg. FIT (KUM) • 3 exs.; same locality; 7–23.VI.2008; A. Watanabe leg. FIT (KUM) • 1 ex.; same locality; 24.V–1.VI.2008; A. Watanabe leg. FIT (KUM). Shimane-ken • 1♀; Dangyô-no-taki, Dôgo Is., Okinoshima-chô; 5–16.VI.2008; T. Shimada leg. (KUM). Okayama-ken • 1 ex.; Kanehira, Bicchu-chô (alt. 300 m), Takahashi-shi; 22.V–2.VI.2010; A. Watanabe leg. FIT (KUM) • 1 ex.; same locality, Takahashi-shi; 2–19.VI.2010; A. Watanabe leg. FIT (KUM). Hiroshima-ken • 1♂; Mt. Tate-eboshi (alt. 1,180 m) [35.0527, 133.0696], Shobara-shi; 15.VI.2024; TS. Nozaki leg. (KUM) • 1 ex.; Kakezu-yama, Higashiyawatahara (alt. 850–1,126 m), Kitahiroshima-chô; 30.IV–9.V.2009; TA. Nozaki & Y. Nozaki leg. FIT (KUM) • 2 exs.; same locality; 9–18.V.2009; TA. Nozaki & Y. Nozaki leg. FIT (KUM) • 1 ex.; same locality; 30.V–13.VI.2009; TA. Nozaki & Y. Nozaki leg. FIT (KUM) • 5 exs.; same locality; 13–27.VI.2009; TA. Nozaki & Y. Nozaki leg. FIT (KUM) • 1 ex.; same locality; 27.VI–4.VII.2009; TA. Nozaki & Y. Nozaki leg. FIT (KUM) • 1♂, 1 ex.; same locality; 4–18.VII.2009; TA. Nozaki & Y. Nozaki leg. FIT (KUM). Yamaguchi-ken • 1 ex.; Nodani, Tokuji-chô; 21.IV.2004; Y. Fujitani leg. (KUM). Shikoku: Tokushima-ken • 1 ex.; Meoto-ike, Tsurugi-chô; 30.VI.2006; H. Fujimoto leg. (KUM). Kagawa-ken • 2 exs.; Nagara-dam, Ayakami-chô; 5.V.2003; S. Nagashima leg. in litter (KUM) • 2 exs.; Shôzaka, Sogisho-higashi, Ayagawa-chô; 9–12.IV.2009; H. Fujimoto leg. FIT (KUM) • 1 ex.; same locality; 12–18.IV.2009; H. Fujimoto leg. FIT (KUM) • 1 ex.; same locality; 22–30.V.2009; H. Fujimoto leg. FIT (KUM) • 1 ex.; same locality; 25.IV–2.V.2010; H. Fujimoto leg. FIT (KUM). Kochi-ken • 1 ex.; Mt. Tsutsujô-zan (alt. 1,600 m), Ino-chô; 30.VI.2007; TA. (Takasuke) Miyata & TO. (Toshie) Miyata leg. (KUM) • 1 ex.; Ekawa, Nishitosa (alt. 120 m) [33.217, 131.784], Shimanto-shi; 12.V.2023; TS. Nozaki leg. (KUM). Kyushu: Fukuoka-ken • 1♂; Mt. Inunaki, Miyawaka-shi; 22.V.1980; T. Gotô leg. (KUM) • 1 ex.; Mt. Tachibana; 1.VI.1978; K. Yamagishi leg. (KUM) • 1 ex.; same locality; 5.V.1979; K. Yamagishi leg. (KUM) • 6 exs.; same locality; 10–14.V.1996; T. Ueno, Y. Higashiura & H. Goto leg. FIT (cSch) • 4 exs.; same locality; 15–17.V.1996; T. Ueno & H. Goto leg. FIT (cSch) • 1♀, 2 exs.; Mt. Shiouji-yama, Onojo-shi; 8.V.2013; K. Kido leg. FIT (KUM) • 1 ex.; same locality; 12.V.2013; K. Kido leg. FIT (KUM) • 1 ex.; same locality; 18.V.2013; K. Kido leg. FIT (KUM) • 2 exs.; Mt. Hikosan; 13.VI.1966; K. Takeno leg. (KUM) • 1♂, 1♀, 4 exs.; Seinen-no-ie, Hikosan (alt. 800 m), Soeda-machi; 22.V.2011; M. Maruyama & T. Kanao leg. LNJ (KUM) • 2 exs.; Kusenbu-yama; 24.V.2014; K. Kido leg. FIT (KUM) • 1 ex.; Mt. Miyomizu-yama, Miyama-shi; 16.V.1997; T. Ishikawa leg. (KUM). Saga-ken • 1♂; Mt. Ten-zan (alt. 1040 m) [33.339, 130.143], Karatsu-shi; 29.VI.2022; S.T. Inoue & Y. Hisasue leg. LNJ (KUM) • 1 ex.; Mt. Tenzan (alt. 1,000 m) [33.340, 130.142], Saga-shi; 18.VI.2022; Y. Hisasue leg. (KUM) • 2 exs.; Kurinoki-tôge, Mt. Kunimi-yama; 15.V.2019; M. Nishida leg. FIT (KUM) • 1 ex.; Mt. Kurokami-yama, Arita-chô; 18.V.2018; M. Nishida leg. FIT (KUM) • 2 exs.; Mt. Mifune, Takeo-shi; 27.V.1984; S. Naomi leg. (KUM) • 1 ex.; Tosen-zan (alt. 350 m), Ureshino-shi; 19.V.1997; S. Nomura leg. (KUM) • 1 ex.; Tosen-zan, Ureshino-shi; 20.V.2018; M. Nishida leg. FIT (KUM) • 2 exs.; Mt. Tara, Tara-chô; 29.IV.1985; S. Naomi leg. (KUM). Nagasaki-ken • 1♀; Mt. Mitake, Tsushima Is., Tsushima-shi; 31.V.1988; S. Nomura leg. (KUM) • 2 exs.; Tanuki-no-o, Ômura-shi; 8.V.2019; M. Nishida leg. FIT (KUM) • 1 ex.; Mt. Yake, Shimabara-shi; 21.IV.1977; Imasaka leg. (KUM). Oita-ken • 1 ex.; Mt. Takasaki-yama, Beppu-shi; 9.V.2013; T. Miyake leg. FIT (KUM). Kagoshima-ken • 1 ex.; Mt. Kurinodake, Kurino-chô; 29.VI.1995; S. Onoda leg. (SPMN) • 1♂; Nageishidaira, Yakushima Is. (alt. 1,825 m) [30.322, 130.512], Yakushima-chô; 18.VIII.2021; S. Inoue leg. (KUM).
Diagnosis.
This species is distinguished from other species of the genus by the following combination of characteristics: a slightly produced metaventral process (Fig. 13D), median lobe of aedeagus bulbous with a length of approximately 0.47 mm (Fig. 13G). This species is similar to H.ovata and H.japonica, but it can be distinguished by a more flattened and semicircular pronotum, less produced metaventral process, and a bulbous median lobe of the male aedeagus.
Homoeusaprolongata Sawada, 1970b. A. Antenna; B. Pronotum and elytra; C. Zoomed view of elytron; D. Meso- and metaventrite; E, F. Posterior margin of 8th sternite: E. Male; F. Female; G. Median lobe of aedeagus from lateral view; H. Paramere of aedeagus from lateral view; I, J. Spermatheca.
Homoeusaprolongata Sawada, 1970b. A. Distribution map; black star – the type locality (“Shiga Hights”); white circles – collection data examined in this paper; B, C. Snapped images from videos shot indoors, adults raising abdomen to an ant; D. Clear image of a living adult from Nagano-ken.
https://binary.pensoft.net/fig/1483284
Head large; color yellowish brown to dark brown; eyes large. Antennae (Fig. 13A) short; relative length of each antennal segment from first to 11th, 2.39: 1.78: 1.14: 1.17: 1.00: 1.01: 1.10: 1.15: 1.20: 1.45: 3.94.
Thorax.
Pronotum (Fig. 13B) semicircular, transverse (PW/PL, 1.51–1.65), widest at posterior 1/3, postero-lateral angle acute to around 90 degrees, posterior margin slightly sinuate, yellowish brown to dark brown, surface finely covered with setae and punctures, gently polished and slightly reticulated. Elytra (Fig. 13B, C) slightly widened posteriad, widest at posterior 1/3, then narrowed roundly, posterior margins deeply notched near lateral corners, yellowish brown to dark brown, surface finely covered with setae and punctures; gently polished and weakly reticulated.
Hind wings developed. Mesoventral process (Fig. 13D) very narrow, with indistinct medial carina, apex sharply pointed, reaching almost anterior margin of mesocoxal cavities. Metaventral process slightly produced.
Abdomen elongate, narrowed posteriad; surface sparsely covered with short setae and each posterior margin with long stout setae; finely reticulated.
Male: 8th sternite (Fig. 13E) weakly produced and angled at postero-medial margin; median lobe of aedeagus (Fig. 13G) bulbous, length about 0.47 mm, apical lobe short and slightly curved ventrally, apex round in lateral view, apical valves elongate and mitten-shaped, dorsal arms short, basal part of copulatory piece large. Paramere (Fig. 13H) length about 0.47 mm; apical lobe of paramere long, length about 1/3 of whole paramere, curved ventrally; four setae, normally arranged, b located a bit more basally than c, velum small.
Female: 8th sternite (Fig. 13F) weakly produced roundly postero-medial margin; spermatheca (Figs 13I, J) S- or C-shaped, apex of basal part slightly sinuate, base largely hooklike.
Variation.
Intraspecies variations are recognized in the apical lobe of the aedeagal median lobe. Some individuals have a small hump at the base of the ventral side and a slightly deeper basal concave. The length of the parameral apical lobe also varies slightly.
Measurements (in mm) and ratios.
Body parts (N = 13): BL ≈ 1.9–2.78; AL, 0.67–0.81; HW, 0.43–0.52; PL, 0.46–0.61; PW, 0.73–0.92; EL, 0.37–0.51; EW, 0.73–0.98; HTL, 0.4–0.48; PW/PL, 1.51–1.65; AL/PL, 1.22–1.53; HTL/PL, 0.8–0.9.
Distribution.
Japan (Hokkaido, Honshu, Shikoku, Kyushu) (Fig. 14A).
Symbiotic hosts.
Lasiusniger species group: L.hayashi, L.japonicus, L.sakagamii, L.productus.
Bionomics.
This species was collected from the nests of host ants under stones and in decaying wood and leaf litter near the entrances to these colonies from April to August. Many individuals were collected using FIT (N = 69). Bait traps set near the nest entrances were also effective in collecting H.prolongata. During indoor observations, H.prolongata was frequently observed, raising the tip of its abdomen toward approaching host ant workers, and sometimes just stopping (Fig. 14B, C).
Remarks.
The type specimens are currently not available. Sawada (1970a, 1970b) described 25 aleocharine species from Shiga Heights, Nagano Prefecture, Honshu, including H.prolongata. According to Takuto Hashizume, who specializes in the taxonomy of homalotines and their relatives, he could not access these type specimens by contacting the National Museum of Nature and Science, Tsukuba (“National Science Museum Tokyo”), which is designated in papers as a deposit, or by searching the Osaka Museum of Natural History, Osaka, Japan. However, the original descriptions and drawings of H.prolongata are sufficiently informative for species-level taxonomy. Therefore, we conclude that a neotype designation is not necessary currently.
Maruyama et al. (2013) reported that some individuals similar to H.prolongata were found in trails of the Lasiusfuliginosus group. However, we did not find any specimens of H.prolongata mounted together with L.fuliginosus. H.ovata may have been misrecognized as H.prolongata because some individuals of H.ovata resemble H.prolongata in terms of body size and general habitus.
Paratype. Japan: Hokkaido • 1♀; Makoi, Shari-chô; 28.V.2000; Y. Kida leg. LUM (KUM) • 2♀♀; Tôro lakeside, Shibecha-chô; 28.VII.1986; S. Nomura leg. (KUM) • 2♀♀; Nopporo, Ebetsu-shi; 13–21.VI.2000; Shigehisa Hori leg. (KUM) • 1 ex.; Minaminosawa, Sapporo-shi; 16–23.V.2023; Y. Tasaku leg. FIT (HUM) • 1 ex.; Hakken-zan, Sapporo-shi; 31.V.2002; M. Maruyama leg. (KUM) • 1♂; same locality; 20.VII.2022; TS. Nozaki leg. LUU (KUM) • 1 ex.; Obihiro-no-mori (alt. 78 m) [42.8987, 143.1439], Obihiro-shi; 15.VII.2022; TS. Nozaki & H. Nozaki leg. LUU (KUM) • 1 ex.; Higashi-ônura, Nanae-chô; 16.VI.1986; S. Nomura leg. (KUM). Honshu: Iwate-ken • 1♂, 1 ex.; Kitayama-sansakuro, Morioka-shi; 2.V.2020; N. Nakaya leg. LUU (IPMM) • 1 ex.; Kitayama, Morioka-shi; 23.IV–3.V.2024; N. Nakaya leg. FIT (IPMM) • 1 ex.; Mt. Takabora, Kamiyonai, Morioka-shi; 3.V.2024; N. Nakaya leg. FIT (IPMM). Gunma-ken • 1 ex.; Yubisogawa, Minakami-machi; 18.VI.2004; M. Yasaka leg. (KUM). Nagano-ken • 2 exs.; Odairahara, Horigane (alt. 1,100 m), Azumino-shi; 12.VII.1998; M. Maruyama leg. LUU (KUM) • 1 ex.; Fujii, Satoyamabe [36.2513, 137.3436], Matsumoto-shi; 13.V.2021; S.T. Inoue leg. LUU (KUM) • 1 ex.; Iriyamabe, Matsumoto-shi; 30.VI.2012; M. Maruyama leg. LUU (KUM) • 1 ex.; Fujimi (alt. 1,510 m) [35.904, 138.190], Fujimi-chô; 4.VI.2023; TS. Nozaki leg. LUM (KUM). Gifu-ken • 1♀; Nabedaira-kôgen, Takayama-shi; 6.VII.2022; TS. Nozaki leg. LUM (KUM) • 2♂♂, 1♀; Nakao (alt. 1,200 m), Takayama-shi; 5.VI.2005; K. Kinomura leg. LUM (KUM) • 1 ex.; Iwai (alt. 830 m) [36.1320, 137.3436], Takayama-shi; 7.VII.2022; TS. Nozaki leg. LUM (KUM) • 1 ex.; Iwase (alt. 850 m), Takayama-shi; 5.V.2005; K. Kinomura leg. LUU (KUM) • 1 ex.; same locality; 4.VI.2006; K. Kinomura leg. LUU (KUM). Nara-ken • 1♂; Wasamata-yama (alt. 1,140 m) [34.2184, 135.9862], Kamikitayama-mura; 14.VI.2023; TS. Nozaki leg. LUM (KUM). Okayama-ken • 1 ex.; Jabuchi-no-taki, Mt. Nagi-san (alt. 579 m) [35.1567, 134.1908]; Nagi-chô; 15.V.2022; Y. Senda leg. (EUMJ). Hiroshima-ken • 1 ex.; Kakezu-yama, Higashiyawatahara (alt. 850–1,126 m), Kitahiroshima-chô; 27.VI–4.VII.2009; TA (Tatsuya). Nozaki & Yoko Nozaki leg. FIT (KUM). Shikoku: Kochi-ken • 1 ex.; Irazu-keikoku, Tsuno-chô; 14.V.2005; TA. Miyata & TO. Miyata leg. (KUM). Kyushu: Fukuoka-ken • 2 exs.; Takasubaru, Mt. Hikosan [33.4883, 130.9174], Soeda-machi; 18.VI.2021; TS. Nozaki leg. LUU (KUM) • 1♀, 1 ex.; same locality; 26.VI.2021; TS. Nozaki leg. LUM (KUM) • 2♂♂; Biol. Lab. KU, Hikosan, (alt. 750 m) [33.4806, 130.9090], Soeda-machi; 26.V.2021; TS. Nozaki leg. LUU (KUM) • 1 ex.; Zuibai-ji, Itoshima-shi; 8.V.2021; T. Hashizume leg. (KUM) • 3 exs.; Mt. Shaka-dake, Kitayabe, Yame-shi; 18.V.2017; S. Imasaka leg. FIT (KUM). Saga-ken • 1 ex.; Kurokami-yama, Arita-chô; 27.IV.2018; M. Nishida leg. FIT (KUM) • 1 ex.; same locality; 9.V.2018; M. Nishida leg. FIT (KUM). Kumamoto-ken • 1♂; Momiki (alt. 890 m) [32.494, 130.988], Yatsushiro-shi; 24.V.2023; TS. Nozaki leg. LUM (KUM) • 1♀; Mt. Shiratomi-yama [33.4883, 130.9174], Yatsushiro-shi; 3.V.2022; Y. Uehara leg. (KUM). Oita-ken • 1♀, 3 exs.; Mt. Sobo; 17.V.1986; S. Nomura leg. (KUM) • 1 ex.; Tsukahara, Yufu-shi; 16.V.2014; T. Hada leg. (KUM).
Diagnosis.
This species is distinguished from other species of the genus by the following combination of characteristics: pronotal posterolateral angle distinctly acute (Fig. 15B); elytra distinctly widened posteriad entirely (Fig. 15B, C); metaventral process slightly produced (Fig. 15D); median lobe of aedeagus bulbous, length approximately 0.63 mm (Fig. 15G). The appearance of this species is similar to H.laevigata and H.prolongata, but it can be distinguished from H.laevigata by its normal long setae of pronotum and elytra, and from H.prolongata by its larger body, aedeagus, and distinct acute posterolateral angle.
Homoeusagigantea sp. nov. A. Antenna; B. Pronotum and elytra; C. Zoomed view of elytron; D. Meso- and metaventrite; E, F. Posterior margin of 8th sternite: E. Male; F. Female; G. Median lobe of aedeagus from lateral view; H. Paramere of aedeagus from lateral view; I. Spermatheca.
Homoeusagigantea sp. nov. A. Distribution map; black star – the type locality; white circles – collection data examined in this paper; B, C. Living adult in a foraging trail of Lasiusumbratus under a stone, Morioka-shi, Iwate-ken, Honshu (photographed by Naoya Nakaya); D. Snapped images from videos shot indoors, adults rubbing abdomen against a host ant worker; E. Clear image of a living adult from Nagano-ken.
https://binary.pensoft.net/fig/1483286
Head small; color yellowish brown to brown; eyes small. Antennae (Fig. 15A) short, relative length of each antennal segment from first to 11th, 2.91: 2.25: 1.66: 1.27: 1.18: 1.2: 1.23: 1.18: 1.00: 1.45: 4.93.
Thorax.
Pronotum (Fig. 15B) semicircular, transverse (PW/PL, 1.62–1.80), widest at posterior 1/3, postero-lateral angle distinctly acute, posterior margin distinctly sinuate, yellowish brown to brown, sometimes slightly transparent, surface finely covered with long setae and punctures, gently polished and slightly reticulated. Elytra (Fig. 15B, C) distinctly widened posteriad entirely, posterior margins deeply notched near lateral corners, yellowish brown to brown, surface finely covered with long setae and punctures; gently polished and weakly reticulated. Hind wings developed. Mesoventral process (Fig. 15D) very narrow, with indistinct medial carina, apex sharply pointed, reaching almost anterior margin of metaventrite. Metaventral process slightly produced (Fig. 15D).
Abdomen elongate, remarkably narrowed posteriad; surface sparsely covered with short setae and each posterior margin with long stout setae; weakly reticulated.
Male: 8th sternite (Fig. 15E) weakly produced and angled at postero-medial margin; median lobe of aedeagus (Fig. 15G) bulbous, length about 0.63 mm, apical lobe elogate and slightly curved ventrally, apex round in lateral view, apical valves elongate and mitten-shaped, dorsal arms short, basal part of copulatory piece large. Paramere (Fig. 15H) length about 0.63 mm; apical lobe of paramere long, length about 1/3 of whole paramere, curved ventrally; four setae, b located more basally than c; velum small.
Female: 8th sternite (Fig. 15F) weakly produced roundly postero-medial margin; spermatheca (Fig. 15I) S-shaped, apex of basal part slightly sinuate, base largely hooklike.
Variation.
Intraspecies variations were recognized in the apical lobe of the aedeagal median lobe. Some individuals have a small hump at the base of the ventral side and a slightly deeper basal concave. The length of the parameral apical lobe also varies slightly.
Measurements (in mm) and ratios.
Body parts (N = 10): BL ≈ 2.48–4.3; AL, 0.92–1.15; HW, 0.55–0.64; PL, 0.67–0.83; PW, 1.09–1.39; EL, 0.51–0.62; EW, 1.06–1.34; HTL, 0.61–0.75; PW/PL, 1.62–1.80; AL/PL, 1.22–1.46; HTL/PL, 0.89–1.02.
Distribution.
Japan (Hokkaido, Honshu, Shikoku, Kyushu) (Fig. 16A).
Symbiotic hosts.
Lasiusumbratus species group: L.umbratus, L.meridionalis.
Bionomics.
Homoeusagigantea sp. nov. is rarely observed in host ants’ trails under stones or soil from April to July (Fig. 16B, C). Some individuals were collected by FIT (N = 15). Setting baits near the ants’ foraging trails under stones (like Fig. 1C) is effective for collecting H.gigantea sp. nov. During indoor observations, they frequently and proactively rubbed their abdomen against body of their host ant workers (Fig. 16B, D), unlike any other species of this genus.
Remarks.
Not many specimens were collected from foraging trails without bait. This might be because of the foraging behavior of the host ant species, Lasiusumbratus and L.meridionalis. Both species are members of the Lasiusumbratus group (formerly called the subgenus Chthonolasius Ruzsky, 1912) considered to forage mainly underground (Donisthorpe 1927; Collingwood 1979; Seifert 1988). We also observed these Lasius species forming trails under stones or inside litter. Given this, we believe that they tend to forage mainly underground. To find Homoeusagigantea sp. nov. in these trails naturally, first, a collector needs to find the trail. At the same time, the beetle must pass through the right stone on the long path all over the underground region. This is why a bait trap is effective. It can attract many ant workers and beetles under a particular stone. TN collected multiple individuals per bait set under a stone, suggesting that the species may potentially be more common than expected in their foraging trails.
Etymology.
The specific name is derived from the Latin adjective, which means “huge” and refers to the large size of this new species.
Paratypes. Japan: Honshu; Wakayama-ken • 1♂; Kimitoge Pass, Hashimoto-shi; 6.VII.2014; T. Ito leg. (OMNH) • 1♀; same locality; 9.VII.2008; T. Ito leg. (OMNH) • 1 ex.; Tsuchibotoke-tôge, Iwade-shi; 10.V.2019; I. Matoba leg. (OMNH) • 1♀; same data as holotype (KUM) • 2♂♂, 3♀♀; Nishihara (alt. 180 m) [33.781, 135.413], Hidakagawa-chô; 11.VI.2023; TS. Nozaki leg. LFS (KUM).
Diagnosis.
This species is distinguished from other species of the genus by the following combination of characteristics: pronotal postero-lateral angle around 90 degrees (Fig. 17C); metatarsi shorter than half of metatibiae (Fig. 17F, G); apical lobe of paramere short, broad, and almost straight, length about 1/4 of whole paramere, apex distinctly truncate (Fig. 17K). This species is similar to H.japonica and H.prolongata in general appearance, but it can be distinguished from these two species by its very short metatarsi and truncate apex of the parameral apical lobe.
Homoeusabrevitarsis sp. nov. A, B. Antenna; A. Male; B. Female; C. Pronotum and elytra; D. Zoomed view of elytron; E. Meso- and metaventrite; F, G. Hind tibia and meta-tarsus; F. Male; G. Female; H, I. Posterior margin of 8th sternite; H. Male; G. Female; J. Median lobe of aedeagus from lateral view; K. Paramere of aedeagus from lateral view; L. Spermatheca.
Body (Fig. 3G) small, broad; dorsal surface mostly moderately polished.
Head large; color brown; eyes small. Antennae (Fig. 17A, B) short relative length of each antennal segment from first to 11th, 2.48: 1.96: 1.39: 1.22: 1.04: 1.09: 1.00: 1.15: 1.15: 1.37: 3.26.
Thorax.
Pronotum (Fig. 17C) subrectangular, transverse (PW/PL, 1.56–1.66), widest near middle, postero-lateral angle around 90 degrees, posterior margin slightly sinuate, reddish brown, surface finely covered with setae and punctures, gently polished and slightly reticulated. Elytra (Fig. 17C, D) slightly widened posteriad, widest at middle, then narrowed roundly, posterior margins deeply notched near lateral corners, reddish brown, surface finely covered with setae and punctures; gently polished and finely reticulated. Hind wings developed. Mesoventral process (Fig. 17E) very narrow, with weak medial carina, forming Y-shaped, apex pointed, reaching posterior 1/3 of mesocoxal cavities. Metaventral process slightly produced.
Abdomen elongate, narrowed posteriad; surface covered with short setae and each posterior margin with long stout setae; finely reticulated.
Male: Metatarsi (Fig. 17F) as long as 1/3 of hind tibia. 8th sternite (Fig. 17H) produced roundly at postero-medial margin; median lobe of aedeagus (Fig. 17J) slender, length about 0.61 mm, apical lobe narrow, slightly curved ventrally, apex gently pointed in lateral view, apical valves elongate and mitten-shaped, dorsal arms long and sharpened apically, basal part of copulatory piece small. Paramere (Fig. 17K) length about 0.73 mm; apical lobe of paramere short and broad, length about 1/4 of whole paramere, almost straight, apex distinctly truncate; four setae, b located subapically, c irregularly located more dorsally; velum elongate and narrow.
Female: Metatarsi (Fig. 17G) slightly shorter than half of metatibia. 8th sternite (Fig. 17I) slightly rounded posterior margin; spermatheca (Fig. 17L) apex of basal part slightly swollen, base largely hooklike.
Measurements (in mm) and ratios.
Body parts (N = 8): BL ≈ 2.35–2.87; AL, 0.79–0.88; HW, 0.53–0.59; PL, 0.57–0.64; PW, 0.9–0.99; EL, 0.46–0.52; EW, 0.91–1.04; HTL, 0.6–0.74; PW/PL, 1.56–1.66; AL/PL, 1.35–1.46; HTL/PL, 1.04–1.22.
Differences between sexes: HTL (male, N = 4), 0.69–0.74; HTL (female, N = 4), 0.6–0.66; HTL/PL (male, N = 4), 1.09–1.22; HTL/PL (female, N = 4), 1.04–1.09.
Homoeusabrevitarsis sp. nov. was collected from foraging trails of host ants on the forest floor from May to July. No individual was collected using FIT. Their behavior with the host ants is unknown.
Remarks.
Although several hundred Homoeusa specimens collected from colonies of the Lasiusfuliginosus species group were examined in this study, this new species is only known from the Kii Peninsula, suggesting a restricted distribution.
Etymology.
The specific name is derived from the Latin adjective, which means “short footed” and refers to the short tarsi of this new species.
DiscussionHost association
The association of Homoeusa species with the Lasiusumbratus species group is documented for the first time in this study. Lasiusumbratus and L.meridionalis typically forage underground (Seifert 1988), making it difficult to comprehensively survey their myrmecophilous guests. However, as described in the materials and methods, baiting along ant foraging trails proved to be an effective method for efficiently collecting these guests. These discoveries suggest the possibility of undiscovered Homoeusa species associated with these ants, not only in Japan but also in other regions. The pale coloration of H.gigantea sp. nov. aligns with this observation and is consistent with the general trend seen in other subterranean beetles, which often exhibit reduced pigmentation as an adaptation to low-light environments. A similar case in the New World is Decusaexpansa LeConte, 1866, which is associated with the yellowish Lasius species, L.claviger (Schwarz 1890). These examples may support the proposed association between H.translucida and L.meridionalis.
Dispersal behavior
The flight intercept trap (FIT) has proven to be an effective method for collecting these beetles, particularly H.prolongata and H.gigantea sp. nov. Similarly, many individuals of Homoeusa relatives associated with the Lasiusniger group, such as Aspidobactrussemirbiculatus Maruyama, 2000 and A.toyodai Maruyama, 2000, were collected using FIT (Arai 2005). Interestingly, species associated with the Lasiusfuliginosus group were rarely collected by this method (e.g., only two H.rufescens, one H.ovata in Nozaki and Maruyama 2022a, and two H.japonica). Species that are occasionally collected by FIT seem to share similar microhabitats, such as the interior of L.niger group nests or the subterranean foraging trails of the L.umbratus group. In contrast, species associated with the L.fuliginosus group tend to inhabit relatively open environments, staying close to their foraging trails on the forest floor. Although the dispersal behavior of Homoeusa adults remains unknown, their flight activity may be influenced by habitat differences.
Life history
The complete life cycle of Homoeusa remains a mystery due to the limited available data. The active period of adults generally spans from spring to early summer, but this range may be broader and extend later at higher latitudes or altitudes. H.acuminata Märkel, 1842, which is associated with L.fuliginosus (Latreille, 1798), has been observed from May to September in southwestern Belgium (Quinet and Pasteels 1995). Outside this period, adults are rarely found near Lasius nests, with only a few exceptions. Despite the large numbers of adult beetles observed during their active season – particularly in species associated with the L.fuliginosus group, such as H.ovata (Nozaki and Maruyama 2022a) – no larvae have been recorded. This suggests that larvae may reside deep inside the ant nests and depend on host resources. They may pupate in cryptic places and stay there during the teneral period for a while after emergence because teneral adults are nearly absent on the forest floor.
Interactions with the host ants
Responses to host ant workers vary across Homoeusa species and include behaviors such as ceasing movement, exposing the tip of the abdomen, grooming the ants, engaging in trophallaxis with workers, and rubbing their abdomen against the ants. These behavioral strategies likely function to mitigate host aggression. In this context, the variation in responses may be explained by factors such as body size and chemical strategies. Species that are significantly smaller than their host ants, such as H.ovata and H.rufescens, simply stop moving when confronted by their hosts. Small-sized symbionts are often overlooked by their hosts and may minimize detection risk by remaining motionless (von Beeren et al. 2021). In contrast, larger species like H.japonica and H.longicornis raise their abdomens when interacting with their hosts. This behavior resembles the “appeasement” strategy observed in Dinardadentata (Gravenhorst, 1806), in which individuals are thought to release volatile chemicals from exocrine glands to reduce host aggression (Hölldobler and Kwapich 2019). Due to their large size, these beetles may not be able to evade detection simply by ceasing movement, necessitating the use of chemical defenses.
Chemical mimicry
Ant colonies primarily rely on cuticular hydrocarbons (CHCs) for nestmate recognition, as these compounds serve as species- and colony-specific chemical signatures (Lenoir et al. 2009). Homoeusalaevigata appears to exploit this system by mimicking nestmate behaviors such as licking the ants’ bodies and soliciting food, which may facilitate their acceptance within the colony. So far, grooming and trophallaxis behaviors have been observed exclusively in H.laevigata among Homoeusa species. These behaviors are presumed to aid in chemical mimicry by acquiring CHCs from their hosts, similar to the mechanism proposed for the ant cricket Myrmecophilusalbicinctus Chopard, 1924 (Komatsu et al. 2009). The rubbing behavior exhibited by H.gigantea sp. nov. remains difficult to interpret. This behavior may represent another means of acquiring CHCs, but further investigation is required.
Conflict of interest
The authors declare that no competing interests exist.
Ethical statement
No ethical statement is reported.
Funding
This study was supported in part by a JSPS KAKENHI Grant Number JP22770085, JP23KJ1740.
Author contributions
Conceptualization: TN, MM. Data curation: TN. Funding acquisition: MM, TN. Resources: MM, TN. Supervision: MM. Visualization: TN. Writing – original draft: TN, MM. Writing – review and editing: TN, MM.
Data availability
All data that support the findings of this study are available in the main text.
Acknowledgements
We are deeply grateful to all collectors for kindly offering the specimens and Hirofumi Fujimoto, Fuminori Ito, Yuki Kamite, Kyoichi Kinomura, Takato Kobayashi, Takasuke Miyata, Toshie Miyata, Kôji Mizota, Takeyuki Nakamura, Tomoko Okamoto, Jun Soma, Kohei Suzuki, among others for helping us in the field surveys. We are deeply appreciative of Taku Shimada, Takuto Hashizume and Naoya Nakaya for kindly allowing the use of photographs of living individuals. We would like to show our great appreciation to Roger Booth, Tadashi Ishikawa, Toshio Kishimoto, Keita Matsumoto, Hirofumi Moriya, Harald Schillhammer, Michael Schülke, Yasutoshi Shibata, Matthias Seidel, Shusuke Shimamoto, Shuji Watanabe, Takeo Yamauchi, and Hiroyuki Yoshitomi for kindly lending specimens or helping us obtain specimens deposited in each institution/private collection. We also greatly appreciate Kazuo Ichikawa for his financial support for our research. We would like to thank Editage (www.editage.jp) for English language editing. Finally, we express our gratitude to reviewers, Jan Klimaszewski and Quiyari Santiago-Jiménez for their helpful comments on the manuscript. Museum für Naturkunde (Berlin) waived the publication costs of this article.
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