Corresponding author: Manfred Asche (
Academic editor: Dominique Zimmermann
The genus
Meanwhile several more plesiodelphacine species were discovered in the Neotropics, and are currently subject of a revision of the whole group (Asche, in preparation). The finding of persistent populations of a new
The specimens were collected by sweeping or by visual search directly from the host plant, and preserved dry. Measurements and line drawings were made by using a Leitz stereomicroscope with camera lucida attachment. Genital structures were examined after the whole abdominal were macerated for 24 hours at room temperature in KOH, subsequently transferred to glycerine (for drawings to glycerine jelly). Photographs were taken by the digital camera Canon50D with a MP-E 65mm Macro Photo Lens and by some compact digital cameras in the field, arranged by Paintshop Pro X4. The terminology used for bodily parts including male genitalia largely follows
Depositories: Laboratory of Entomology, Tokyo University of Agriculture, Atsugi, Japan
Museum für Naturkunde, Humboldt Universität, Berlin, Germany
Ryukyu University Museum, Okinawa, Japan
(modified from
We refrain from the establishment of a separate subgenus for the Japanese species based on certain morphological differences from Neotropical
Neotropical Region (6 species, one of which two subspecies), South East Palaearctic Region: Japan (one species described below, new record).
Slender, medium-sized delphacid species of delicate appearance with strongly pale-dark contrasting colouration of the head.
Length (from tip of head to apex of tegmina): Males (n=20): 4.0–4.4 mm (mean 4.2 mm); Females (n=20): 4.3–4.7 mm (mean 4.5 mm)
Colouration: Ground colour pale yellow to orange. Vertex pale yellow, with a narrow transverse dark brown to blackish stripe across the posterior margin of the anterior compartment; lateral margins, posterior corners and converging anterior carinae blackish brown; transition to frons as well as dorsal part of median frontal carina blackish. Frons pale yellow, lateral margins blackish, median carina centered in a narrow black-brown stripe. Post- and anteclypeus orange, median carina of postclypeus brownish. Rostrum orange with black tip. Antennae sordid orange-brown; scape distally fringed blackish-brown; pedicel anteriorly with a broad oblique brown stripe which is distally darker. Sides of head in front and dorsally of compound eyes broadly marked black, posterior corners above compound eyes blackish; compound eyes bright red; sides otherwise pale yellow to orange; ocelli centered in a brown spot; oblique genal carina anteriorly fringed brown; lower part of genae pale yellow; lamina mandibularis (lorae) orange. Pronotum sordid pale yellow, carinae of disk and posterior margin brownish, sides behind compound eyes anteriorly brown; laterodistal part of pronotum pale yellow, anteriorly with a blackish fringe. Mesonotum and tegulae sordid orange-brown. Tegmina translucent, smokey pale yellow or light sordid brown, veins light brown. Hind wings hyaline with brown veins. Legs orange to pale yellow, distal outer margin of tibiae brown. Abdominal tergites and sternites as well as male and female genitalia, mostly orange; ovipositor and posteromedian parts of tergite IX brown, anal style in males brownish, and females blackish.
Head and thorax: Head with large compound eyes, narrow vertex and frons; head including compound eyes about 3 times wider than vertex at base, about 0.8 times narrower than maximum width of pronotum. Vertex elongate, narrow, medially about 1.87 times longer than wide at base, distinctly projected in front of compound eyes; lateral margins subparallel, slightly converging towards apex, apex in dorsal view truncate; compartments of vertex concave, limited by faint but well recognizable carinae; basal compartments elongate, anteriorly limited by anteriorly diverging carinae; anterior compartment rhomboid, lateral carinae converging towards apex and medially continuing as median frontal carina; transition of vertex to frons in lateral view in an almost right angle, apically slightly rounded. Frons elongate, apically rather narrow, continuously widening towards frontoclypeal suture, medially about 2.1 times longer than maximally wide, widest at frontoclypeal suture, basally about 3 times wider than apically, frons medially about 1.3 times longer than post- and anteclypeus together; lateral frontal carinae ridged, very slightly convex, in parts nearly straight, diverging from apex towards base; median frontal carina distinctly ridged, frontal surface in upper part shallowly concave, in lower part almost plain or slightly convex; frontoclypeal suture almost straight. Postclypeus vaulted, median carina ridged, lower part forming a nose-like projection (best seen in lateral view). Antennal joints subcylindrical, elongate, terete; pedicel about 2.8 times longer than scape, furnished with about 16 sensory plaques, arranged in 7 groups, partly in rows. Compound eyes large, in lateral view flat kidney-shaped, mediobasal incision above antennal base distinct, ocelli well developed; oblique genal carina sharply ridged. Pronotum about 3.6 times wider than medially long, carinae of disk sharply ridged, attaining posterior margin, lateral carinae slightly convex, diverging posteriorly; surface of disk shallowly concave. Mesonotum medially about 2.6 times longer than pronotum, carinae ridged, lateral carinae very slightly concave, diverging towards and attaining the posterior margin, median carina vanishing before reaching scutellum; surface of disk nearly plane. Tegulae well developed, in dorsal view about as long as wide. Tegmina elongate and narrow, about 4.5 times longer than maximally wide, widest shortly distad of nodal line, the latter in distal third; subapical cells small and narrow, inner cell (C5) slightly longer than outer one (C1), in membrane M branched into M1 and M2. Margin of hind wing with distinct notch at A1, M distally branched. Legs slender; hind leg with tibia about 1.25 times longer than tarsal joints together, laterally furnished with 2 spines, one close to base, the other shortly below midlength, distally with 5 spines: 2 rather small ones inside, 3 increasingly longer ones towards outside; post-basitarsus about twice as long as 2nd and 3rd post-tarsal joints together, distally with 5 spines: 4 in a row, one spine positioned anteriorly out of row; 2nd post-tarsal joint distally with 4 spines: the 3 inner ones forming an oblique row, the outer one distinctly longer.
Abdomen slightly depressed, hypopleurites subrectangular with straight outer margin. Male drumming organ with paired apodemes of the second abdominal sternite elongate, erect, slightly widening dorsally, nearly attaining tergites.
Male genitalia: Genital segment in lateral view trapezoidal, ventrally about 1.3 times longer than dorsally, laterodorsal corners slightly produced, caudal margin nearly straight; in ventral view medially slightly longer than wide, mediocaudal margin straight with a small central knob; in caudal view ovoid, slightly higher than wide; diaphragm narrow, median sclerotized portions lobe-like with median membranous interruption. Aedeagus relatively short, when exposed hardly surpassing tip of anal segment, in lateral view curved dorsally; central sperm-conducting tube (sheath sensu
Female genitalia: as in all
Male genitalia.
Male genitalia.
Male genitalia.
Male genitalia.
Japan: Kyushu (south-westernmost area), Yakushima Island of the Osumi Isles and Okinawa Island (northern part) of the Ryukyus, endemic.
(see Colour plate
Habitat of
In the field, both nymphs and adults are found near the ground, on stems of the host plant below the level of fallen cedar leaves. Adults may appear from late July with a probable peak at mid- and late August on Yakushima Is.
Since late summer of 2013, M. Hayashi had been rearing several adults collected by Fujinuma, on potted ginger-lilies (
The specific name refers to the geographical occurrence in Japan.
Holotype ♂ macropterous, Japan, Kagoshima Pref., Osumi Isles, Yakushima, Yudomari, 20.VIII.2013, S. Fujinuma (
Paratypes: 3 ♂♂, 4 ♀♀, Kyushu, Kagoshima Pref., Minami-Satsuma, Bonotsu, Akime, 17.VIII.2014, K. Ôhara (
For the first time a representative of the plesiodelphacine
It is noticeable that the Japanese
The extension of the range of occurrence of
Examples of recent New World introductions to Europe across the Atlantic are known, e.g., the (presumed invasive) American delphacine
Although we cannot fully exclude the possibility of a recent introduction of a
A rather similar distribution pattern is observed in another group of
Similar biogeographic patterns have also been reported from other groups of organisms, (e.g.,
Although a far more recent distributional pathway across the Beringian bridge in Cenozoic times is theoretically conceivable (V.M. Gnezdilov, personal communication), there is no evidence for a historic occurrence of this group in the Holoarctic Region.
Fossil records for
We are grateful to Takeshi Sasaki (
We wish to thank Manuela Hager and Andreas Wessel (Museum für Naturkunde, Berlin) for lending their time and skills to image processing and layout the photographic plates. Two reviewers provided valuable comments which substantially improved the manuscript. Their support is greatly appreciated. A very special