Records and descriptions of caddisflies from Natma Taung National Park and adjacent localities in the Chin Hills of Myanmar (Insecta, Trichoptera)

During several excursions to the Chin Hills of Myanmar from 2001 to 2015, rich collections of caddisflies were made which form the basis of the present taxonomic and biogeographic study. A total of 106 species were identified including seven new species. They are described as Arctopsyche subflava sp. nov., Hydromanicus abdominalis sp. nov., Cheumatopsyche janosolahi sp. nov., Lepidostoma subpanaitos sp. nov., Aplatyphylax pumilus sp. nov., Adicella natmataungensis sp. nov. and Triaenodes mindatensis sp. nov. Illustrations of the male genitalia and images of the adults are provided. Two species names were recognised as junior synonyms: Hydropsyche athamas Malicky & Chantaramongkol, 2000, = Hydropsyche januha Oláh & Barnard, 2008, syn. nov.; Hydropsyche khasigiri Oláh & Barnard, 2008, = Hydropsyche kiogupa Oláh & Schefter, 2008, syn. nov. In an attempt to determine the biogeographic character of the fauna, the known ranges of all resident species were plotted into three longitudinal transects from 85°–95°E, 95–98°E and 98°–108°E, ranging from the eastern Himalayas to northern Vietnam. About half of the species have ranges extending over all three transects. The fauna is equally composed of western and eastern species qualifying the Chin Hills as part of a transition zone including palearctic elements. Most of the species, which are widely distributed in south-east Asia, are members of the suborder Annulipalpia. The investigations of the authors yielded 77 autochthonous species, which have been unrecorded from the country including the newly-described taxa. This brings the number of species records from Mynamar to 304.


Introduction
Local inventories are key data resources for measuring insect diversity, recognising ranges of taxa and planning conservation activities. Inventories provide enduring information and are archives of life, assuming that the sampled material is stored and conserved adequately. Many such inventories are needed in each country to reveal the general and unique features of a country`s insect fauna and of the biogeographic regions of which the country is a part.
There is only one locality in Myanmar which can be regarded as intensively sampled for Trichoptera, the area around Kambaiti in the Miytkyina District of the Kachin Province. It is about 5 km from the Yunnan border and situated at an elevation of 2000 m. The collector was René Malaise and his wife Ebba. The couple spent three and a half months at this place in 1934 collecting huge amounts of insects by using traps designed by R. Malaise and later named after him (Vårdal and Taeger 2011). Back in Sweden, the material was sorted to systematic groups and sent out to specialists for identification and description. The Trichoptera were studied first by A. V. Martynov, M. S. Mosely and D. E. Kimmins for material sent to the former British Museum (Natural History), London, today the Natural History Museum, London. They included in their studies additional material from collections made during the British colonial times in India and Burma. Later on, examination of the Malaise material was continued by F. Schmid, H. Malicky, K. Johanson, J. Oláh and others. A complete list of species was, however, not published by these authors. This task was accomplished by Wityi et al. (2015), who retrieved and compiled all species description from the various publications of Martynov, Mosely, Kimmins, Schmid, Malicky and others. Moreover, they provided the first synopsis of the Trichoptera of Myanmar, not only based on literature, but with the addition of results from their own fieldwork in the Chin Hills in Myanmar from 2012-2014. In recent years, fieldwork in Myanmar was started by P. Laudee from his base in Thailand. He carried out some collecting trips to various localities in eastern Myanmar. The results of his excursions were new species descriptions which were published afterwards in close cooperation with H. Malicky (e.g. Laudee and Malicky 2018).
In 2002, the first author (WM) joined an excursion to the Chin Hills organised by Dr. Stefan Naumann (SN) (Berlin), who travelled to the area the year before in search of Saturniidae and Eupterotidae (Lepidoptera, Macroheterocera), lepidopteran families for which he is one of the world's leading specialists. With the participation of WM, the objectives of the 2002 excursion were extended to include Microlepidoptera and Trichoptera in an effors to gather information from this then largely unexplored mountain range. During this short excursion, adult caddisflies were sampled at several locations and altitudes in the Natma Taung National Park (NTNP) and in adjacent areas. SN visited the Chin Hills repeatedly in subsequent years until 2015 and brought back additional samples of caddisflies that he donated to the Museum für Naturkunde, Berlin (MfN). Examination of the collected material immediately started after returning from Myanmar in 2002, but came to an abrupt stop due to more urgent commitments of the first author. The study of the Trichoptera samples was resumed in 2019 and first results were published by Malicky and Mey (2020). The purposes of the present article are to summarise all data on Trichoptera collected by the author and SN in the Chin Hills including the NTNP and to provide further new taxa descriptions. This information was used as an initial attempt to recognise species distribution patterns in SE Asia and to determine the biogeographic character of the fauna of the Chin Hills.

The Chin Hills and the Natma Taung National Park
The Natma Taung National Park (NTNP) is one of Myanmar`s 43 currently existing protected areas (Beffasti and Galanti 2011). It is situated in the southern Chin Hills, Chin State, in western Myanmar, west of the Ayeyawaddy River (= Irrawaddy River), occupying the higher elevations of this mountain range (Figs 1, 2A, B). The Chin Hills are part of the Burma Arc, a range of mountain systems extending for 700 km from the Eastern Himala-yas in the north to the Arakan-Yoma range in the south. The Andaman and Nicobar Islands in the Gulf of Bengal are geologically the southern prolongation of this arc. The Burma Arc is of early Tertiary origin and was uplifted by the docking of the Indo-Australian Plate to the Asian continent. It is part of the West Burma Block, a continental terrain of Gondwanan origin that was accreted together with other terrains to Asia in the Late Cretaceous (Metcalfe 1996). The Park covers an area of 723 km 2 and rises with the summit Natma Taung (= Victoria Peak) (Fig. 2F) to a height of 3051 m (Woo Shin Lee et al. 2016) The monsoon climate is characterised by a long rainy-wet season from May to early December with mean annual rainfall of 1,763 mm. Rain in the dry season and frosts at higher elevations occur regularly. In Kanpetlet, one of the three townships close to the NTNP, the mean annual minimum and maximum temperatures are about 12 °C and 25 °C, respectively. The vegetation of the NTNP was studied by Kingdon-Ward (1958). He differentiated three types of forest: monsoon forest up to 1000 m, subtropical evergreen forest from 1000-2130 m and temperate, semi-evergreen forest above the mist line to the summit. Trees of Quercus semicarpifolia, Pinus kesiya and Rhododentron arboretum dominate the vegetation at high altitudes. NTNP was established in 1997 to preserve plant species endemism, rare birds and to protect the catchments of two large and several smaller rivers on which about 3 million people of the Chin tribe depend. The area is an important reservoir of plant and animal biodiversity. High plant species endemism and a number of different forest communities are outstanding features of the NTNP (Kingdon-Ward 1958; Kang et al. 2017). A first survey on the animal biodiversity was published by Woo Shin Lee et al. (2016) which contains chapters on conspicuous species of selected insect groups (Lepidoptera, Odonata, Coleoptera, Hemiptera, Orthoptera). Trichoptera and most other aquatic groups were not included. The presence of human settlements in the NTNP is increasingly impacting forests and biodiversity. Shifting cultivation, the traditional way of life of the local Chin people and extensions of other agricultural activities are major threats to the National Park (see Fig. 2H The sampling of caddisflies concentrated on adults, which were collected by sweeping the riparian vegetation along watercourses with hand-nets in the daytime. Collecting at night in 2002 was performed with a 12V battery-operated light-tower (2 × 15 Watt, superactinic light tubes, F. Weber Company, Stuttgart, Germany). The tower was in operation for about 4 hours starting at sunset and finishing, when the temperature dropped below 6 °C and insects ceased arriving. Most of the material, sampled by SN, was gathered at the lights by picking up the insects manually from a white sheet illuminated by a single 160 or 250 W bulb. The lamp was powered by a Honda Ex 350 generator. Most of the imagines were immediately preserved in ethyl alcohol (75%), while others were pinned or micro-pinned and stored dry in small boxes. Dry preserved specimens are indicated as pinned, while the remaining material is preserved in ethyl alcohol. The material is deposited in the Museum für Naturkunde, Berlin (MfN), with voucher specimens in the collection of the second author.
In contrast to the practice for Lepidoptera, the descriptions of new species of Trichoptera are rarely accompa- nied by photos of the adults. Most articles about Trichoptera in south-east Asia go without. We decided to publish images of some species, demonstrating in this way, the diversity of forms and colours of adults, including some types of new species described herein. Dissection of genitalia was performed according to the procedure described by Robinson (1976). The genitalia of small species were embedded in Euparal on permanent slides. Chlorazol Black was used for staining. The cleared abdomens of the larger species were transferred either into polyethylene vials with glycerine on the pins or placed together with the corresponding specimens into alcohol vials. Prior to embedding on permanent microscope slide or into glycerine vials, genitalia were drawn using a camera lucida attached to a Leica MZ12 compound microscope. The illustrations were scanned and processed in Photoshop. Photographic documentation of imagines and genitalia were performed with a Nikon Coolpix. Terminology used in the description of the species follows common practice exemplified by Schmid (1998). The treatment of families and species are arranged in systematic order as applied by Malicky (2010).
All identified species of the Chin Hills are listed systematically according to family affiliation and, within those, in alphabetical order. Their known distributions are indicated by using country abbreviations in the three columns of the table representing the three transects. Information about the original description of the species, on bibliographic data and references to synonyms are available from the Trichoptera World Catalogue of Morse (2020). This catalogue was regularly consulted for checking the correct writing of taxonomic names.
The biogeographic affinities of the new species, described from the Chin Hills, were derived from the location or range of their nearest relatives, which are noted and discussed in the diagnoses of the species descriptions. In some cases, the assignment is un-problematical (cf. Arctopsyche subflava sp. nov.), whereas in others, a clear assignment to one of the three transects was not possible because closely-related species are present in several transects. The distributions of these species are indicated with an asterix (*) that may occur in more than one col-umn. The comparison of species numbers per transect is thought to provide chorological patterns of Trichoptera species distributed in the area between the Himalayas and northern Vietnam. It is, admittedly, a rough analysis, but in the absence of sufficiently accumulated knowledge of range patterns, the method may provide some useful insights into the biogeographic character of the fauna of the Chin Hills and into the distribution patterns of species in south-east Asia and adjacent areas.  Kimmins, 1953 Fig. 3B Material. 1 ♂, Myohaung Camp, 2060 m a.s.l., area of Mt. Victoria, 3-5.x.2002, LF, leg. W. Mey, photo 06/20, (pinned).

Chimarra argax
Remarks. The male genitalia of this species are variable. In Fig. 5D-F, the male genitalia of the single specimen are depicted.
Remarks. There is a number of very similar species with a large distribution in south-east Asia displaying a certain variation in male genitalia (Malicky 2018). In some cases, we were not able to discriminate between local variations or different species. (Kimmins, 1955) Material. 1 ♂, 8 miles camp, 2500 m a.s.l., 6-8.x.2002, LF, leg. W. Mey, genitalia in glycerine vial, (pinned).
Diagnosis. The new species shares with A. inaequispinosis Schmid, 1968 (described from Sikkim) 1) the pale-yellow band on the forewings and 2) a similar architecture of the male genitalia. The species differ in the form of the bifid intermediate appendages, with longer dorsal branches in A. subflava sp. nov. and longer ventral branches in A. inaequispinosus. The second segment of the inferior appendages has a prominent ventral keel in the new species, whereas this keel is inconspicuous and flat in A. inaequispinosus. Both species form a species pair in the A. composita group (sensu Schmid 1968) with allopatric distribution ranges in the Himalayas (A. inaequispinosus) and Chin Hills (A. subflava sp. nov.).
Description. Forewing length 14 mm, wing span 30 mm. Head and antennae pale yellow, eyes large, hemispherical, cephalic dorsal warts with pale yellow hairs, hairs on occiputal warts black, labial and maxillary palpi brown; mesonotum dark brown laterally and with median, pale yellow band bearing short, yellow hairs; tegulae of forewings with long, black hairs, fork 4 very long, starting at the base of the median cell, wing membrane grey, sparsely covered with short black hairs, membrane with pale spots along costal and apical margins, dorsal margins with a broad, pale yellow band extending on termen (= outer margin) towards wing apices, termen somewhat concave; hindwings membranous, costal area covered with short brown hairs, fork 1 with short stalk.
Male genitalia (Fig. 6D, E). Segment IX with evenly curved anterior margin, segment X membranous, preanal appendages free, large and oval, intermediate appendages with long dorsal and short ventral branches, basal part not broader than pre-anal appendages, inferior appendages with short basal and more elongate apical segments, the latter exhibiting a prominent, slender keel on ventral sides, apical portions slightly bent mediad and deeply excised on the median sides subapically; phallic apparatus with tubular phallotheca and erectile membranous endotheca, containing long, sickle-shaped phallotremal sclerites.
Female. Unknown Distribution. Only known from the Chin Hills, Myanmar.
Biology. Mountainous species with flight period in autumn. Adults are attracted by light.

Diplectrona sanguana Kimmins, 1964
Diagnosis. The new species is assigned to the H. verrucosus group, as defined by Oláh and Johanson (2008b). In contrast to other members of the group, the male abdomen including genitalia, except inferior appendages, is completely yellow, the endothecal processes are round and not elongate and the harpagones are apically   Mey, 1996 (Thailand, Vietnam) seems to be a related species by sharing a similar form of the inferior appendages and the small size of the adults.
Description. Length of forewing 8.7 mm, wing span 18 mm. Head and thorax black, cephalic warts with black bristles, eyes small, interocular index 1.0, antennae black, longer than forewing length, proepistermal setal wart present, legs black, inner spur of fore-tibiae very small, inner ungues of praetarsi with bundle of black hairs; forewings dark brown, with naked (= without hairs) costal field, fork 1 present (Fig. 9A), hindwings sparsely covered by brown hairs, fork 1 present. Abdomen with segments I-II black, remaining segments yellow.
Male genitalia (Fig. 7A-C). Ventral and dorsal part of segment IX narrow; segment X curving dorsad, with short apicodorsal lobes widely separated in dorsal view and with blunt tips in lateral view, lateral sides with spinose margins; inferior appendages black in contrast to other parts of genitalia, as long as phallotheca, coxopodites short and broad at apices, harpagones as long as coxopodites, enlarged apically, flat and twisted; phallic apparatus with phallotheca broad and narrowed subapically, endothecal processes evenly rounded, phallotremal sclerites small, clearly separating endothecal processes at their bases.
Distribution. Myanmar, Chin Hills Biology. Mountainous species with flight period in autumn. Adults are attracted to light.

Cheumatopsyche chryseis
Diagnosis. The new species belongs to the C. holzschuhi group (Oláh et al. 2008a), which is defined by the presence of apicodorsal lobes on segment IX and apicoventral setal lobes on segment X. The male genitalia of the new species resemble C. automedon Malicky & Chantaramongkol, 1997 (Thailand) and C. meyi Malicky, 1997 (Vietnam). Each of these species, however, has specifically-formed harpagones, allowing their clear separation and identification.
Description. Length of forewing 5-5.5 mm. Head and thorax black, cephalic warts with black bristles, eyes small, interocular index 1.0, antennae dark brown, longer than forewing length, indistinct spots at articulations on ventral side; legs brown, inner spur of fore-tibiae very small; forewings brown, with golden-brown macula on subapical costal field, fork 1 present, hindwings sparsely covered by brown hairs, fork 1 present.
Male genitalia (Fig. 7D-F). Ventral part of segment IX broad, dorsal part short and narrow; apicodorsal lobes of segment IX widely separated in dorsal view and with pointed tips in lateral view, apicoventral lobes on segment X short and rounded; inferior appendages shorter than phallotheca, harpagones deeply split into a longer median branch and a shorter, lateral branch; phallic apparatus with phallotheca bulbous at base and narrowed subapically, endothecal processes evenly rounded, oval, phallotremal sclerites large, clearly separating endothecal processes at their bases.
Distribution. Myanmar, Chin Hills. Biology. Mountainous species with flight period in autumn. Adults are attracted by light.

Hydropsyche briareus Malicky & Chantaramongkol, 2000
Material. 2 ♂, 1 km north-east of Falam, 1500-1700 m a.s.l., 21-22.v.2001, genitalia  Remarks. The range of the species extends from eastern Tibet, north-east India, Yunnan to Myanmar. The occurrence in the Chin Hills is the southernmost record suggests an uninterrupted occurrence along the north-south stretching mountain ranges connecting the Chin Hills with the eastern Himalayas.

Micrasema turbo Malicky & Chantaramongkol, 1992
Description. Length of forewing 8 mm. Head brown, second segment of male maxillary palpi with erected bun-dle of black, androconical scales, labial palpi with basal segment very short, terminal segment longer than second segment; scape short, curved and kneed subapically, covered with long bristles, flagellomeres bicoloured, yellow basally and brown apically; forewings brown, small androconial scales sparsely distributed at base and along veins, costal fold with hair comb, end of thyridial cell with naked spot; wing venation in Fig. 8K.
Male genitalia (Fig. 8G-J). Segment IX fused forming compact ring, dorso-mesal processes of segment X long and triangular, with acute tips, lateral processes absent, first article of inferior appendages nearly rectangular at base in lateral view, baso-dorsal process absent, ventroapical process finger-like, rounded at apices, dorsoapical process short, second article slightly shorter than ventroapical process, with apicomesal point; phallicata with basal portion slender and recurved basally, apical half nearly straight and broadened distally, parameres long, slender, symmetrical, longer than phallicata and slightly curved dorsad apically.
Distribution. Myanmar, Chin Hills Biology. Mountainous species with flight period in autumn. Adults are attracted by light. Etymology. Latin, pumilus, pygmy, referring to the small size of the male adults.

Lepidostoma yehuiah
Diagnosis. With 8-9 mm forewing length, the new species appears to be the smallest in the genus. The broadly-rounded apices of the forewings and the absent tessellated bands on abdominal sternites are further distinguishing characters. Concerning male genitalia, the short inferior appendage, the long, free intermediate appendages and the curved parameres are similar with A. unicornis (Mey & Yang, 2001) described from Shaanxi, China. The slightly serrate dorsal margins of the intermediate appendages and the forewing pattern are unique features of the new species, which together with A. unicornis, seems to take an isolated position within the genus. The majority of Aplatyphylax species occur in the Eastern Himalayas from Sikkim to Assam (Schmid 1991b).
Male genitalia (Fig. 9B-D). Tergit VIII with pair of subapical patches of short and black, spaced spines encircling a rounded depression between patches; segment IX in lateral view broadest in the middle, narrow on dorsal and ventral sides; pre-anal appendages relatively broad, long, slightly curved dorsad; intermediate appendages a pair of long, separate processes, not fused at bases, directed dorso-distad, dorsal margin with finely serrated surface; inferior appendages short and shallow, rounded in ventral view. Phallic apparatus large, endotheca extensible, long, with round sclerite on gonoporus; bases of parameres membranous, broad, apical parts sclerotised, hook-like, with apices directed laterad in exposed stadium and mediad in reposed state.
Etymology. The specific epithet refers to the name of the type locality, the summit Natma Taung (= Mt. Victoria).
Diagnosis. The species does not exhibit a clear similarity to any of the known species of China, the Indian or South East Asian regions. According to male genitalia, the species resembles those of the A. pulcherrima group. However, the external morphological criteria of the group, as listed by Schmid (1994) and Yang and Morse (2000), include a cushion of dense, erect hairs on the jugal lobes of the forewings and a brush of long hairs on the jugum of the hindwings. Both characters are imperfectly present in the new species, with short, erect hairs on the base of the anal vein (but not cushion) and with long hairs on the hindwing jugum representing the normal fringes (but not hair brushes). The long segment X with only one pair of dorsal processes and the widely-diverging apical parts have a similar shape in some species of the group, for example, A. papillosa Morse, 2000 from south-western China andA. castanea Kimmins, 1963 from Khasi Hills.
Description. Length of forewings 5.6-6 mm, wing span 13 mm. Head and thorax dark brown, vestiture on setal warts brown, palpi brown, basal segments of antennae and flagellum densely covered by short brown hairs; legs pale brown, spurs 1.2.2; forewings densely covered by brown hairs, maculae absent, jugal area and base of anal veins with short, erect hairs; hindwings sparsely covered by brown hairs, veins darker than membrane, fringes longer than diameter of wings, hair brush on jugal area absent. Male genitalia (Fig. 9E-G). Segment IX in lateral view with straight anterior margin and posterior margin with rounded, medial lobe; pre-anal appendages elon-gate, sub-cylindrical, with long hairs; inferior appendages long, in sub-vertical position, slightly lobed apically on median side, the inner bases with short spicules; segment X valves large, fused dorsally from segment IX to beyond paired dorsal processes, valves widely separated in apical half, deeply excised subapically and pointed at tips. Phallic apparatus with phallotheca curved from broader base, endotheca short, with arched phallotremal sclerite.
Distribution. Myanmar, Chin Hills. Biology. Mountainous species (2500 m a.s.l.) with flight period in autumn. Adults are attracted by light.
Remarks. The individual insect is notably larger than the two preceding species and represents a third species that occurs sympatrically with A. natmataungensis sp. nov.
Diagnosis. In the male genitalia, the new species is closely related to T. trivulcio Schmid, 1994, described from Manipur and T. dusrus Schmid, 1965, described from Yunnan, but differs by the trilobate form of the inferior appendages, which are pointed in T. trivulcio and deeply split in T. dusrus. The forewings of T. mindatensis sp. nov. are brown and bear some dark apical spots. Related species are also T. pentheus Malicky, 2005 and T. menestheus Malicky, 2005, which seem to be widely distributed in South-East Asia (Malicky 2005). The morphology of the inferior appendages is species specific and represents the main diagnostic feature in separating species in this genus.
Description. Length of forewing 8 mm. Head and thorax light brown, hairs of setal warts brown, maxilary palpi covered with long grey-brown hairs, labial palpi short, light brown; antennae yellow-brown, scape with longer hairs apically, flagellum smoothly haired, indistinctly flecked on articulations; legs yellow-brown, smooth, spurs 1.2.2; forewings densely clothed by brown hairs, some darker spots at apex extending into fringes, hindwings membranous, apical area with sparse hairs, fork 1 seemingly absent.
Male genitalia (Fig. 9H-L). Pleural regions of segment IX semi-sclerotised, ventral region projecting caudad, subquadrat in ventral view; pre-anal appendages large, foliaceous, two times longer than wide, somewhat triangular in dorsal view; segment X with long, median process, slightly curved and surpassing tip of segment X; inferior appendages terminating in three lobes, one small middle lobe and larger ventral and dorsal lobes; recurved process of basal plate short, not extending beyond ventral lobes of inferior appendages. Phallic apparatus slender, evenly curved, parallel-sided, with pair of lateral ridges near middle, apical region bulbous, with small endothecal sclerites.

Biogeography
The first information on caddisflies of the Chin Hills and from its National Park was provided by Wityi et al. (2015). They recorded a total of 25 species, 13 of which are found again in this study. Together with the 106 species communicated here, a total of 119 species is now known from the Chin Hills. The number of existing species is certainly much higher. The fieldwork concentrated on the higher elevations and habitats at lower elevations were sampled only sporadically. The resulting family spectrum is therefore that of a mountain fauna, that lacks a number of groups or contains only a few species from speciose families (e.g. Psychomyiidae, Leptoceridae). The Hydroptilidae are completely absent, which appears to be an artifact based on sampling methodology rather than reflecting reality.
From a biogeographical point of view, the fauna of the Chin Hills should resemble the fauna of the Indian Subregion (Franz and Beier 1970), especially the fauna of their north-eastern part, known in the past as Assam, the former Province of British India. The Chin Hills range has a north-south orientation and is connected via the Naga Hills in the north to Assam, a topography that facilitates the formation and presence of a common mountain fauna. Further to the north, the mountain ranges are connected with the Eastern Himalayas, which open a dispersal route of Himalayan or Palaearctic elements to the south. However, this route is also open for the entire montane fauna which is dispersed over numerous mountain ranges, stretching in the west from eastern Tibet, northern Myanmar, Yunnan, Sichuan to Guangxi, northern Thailand and to northern Vietnam in the east. The species present in this transition zone between the Palaearctic and Oriental faunal regions are sometimes difficult to designate as being of Oriental or Palaearctic origin. The distribution ranges of individual species are poorly known in this zone and only a few records are usually available from distant localities. In Table 1, the 106 identified species are listed in systematic order together with indications of their occurrences in three defined longitudinal transects in a west-east gradient. Table 2 gives a summary of the distribution of all species, highlighting the number of species restricted to each section and provides species numbers according to the four suborders in each of the transects. Annulipalpia, Plenitentoria and Brevitentoria are considered as valid suborders, while Spicipalpia is a paraphyletic group encompassing the basal lineages and families of Plenitentoria+Brevitentoria (Thomas et al. 2020). Though not valid in a systematic sense, the taxon has practical value in comparisons of results in faunistic, biogeographic and ecological studies and is used here.
The Trichoptera fauna of the Chin Hills is nearly equally divided into a group of species with a wide distribution in south-east Asia (eastern transect) and into a group whose members are inhabitants of mountain ranges in north-east India and further west (western and central transects). The equal portions of both groups in the composition of the fauna (Table 2) are an argument for considering the Chin Hills as a range situated in the transition zone between "western" and "eastern" faunal elements in the Oriental Region. The width and longitudinal extension of this zone is currently unknown, but should follow the mountain topography including parts of Eastern Bangladesh, eastern India and Western Myanmar. The Chin Hills are situated on the western border of the Ayeyawaddy River watershed. It is a task of future studies to find out whether the transition zone includes the entire watershed or remains restricted to mountain ranges on its western and northern margins.
There are only a few distributional ranges, which are connecting the Chin Hills in the north with Xizang (e.g. Hydropsyche ditalon) or Yunnan and Sichuan (e.g. Rhyacophila assimilis, Himalopsyche navasi, Stenopsyche cazul, Hydromanicus umbonatus, Aplatyphylax pumilus sp. nov.). The species of these distributional types are considered as palearctic elements, whose occurrence in the Chin Hills is further strengthening the character of the fauna as being a mixture of species of different origins.
The mountain fauna of the Chin Hills is dominated by species of Annulipalpia. About 2/3 of the species have wide ranges. The Spicipalpia with species of Rhyacophila spp., Glossosoma spp. and Apsilochorema spp. and the Plenitenoria with species of Lepidostoma spp. have most of their ranges lying in the western transect. A number of these species are certainly endemics with ranges centred in the north-east of India.

Discussion
The discovery of 19 hitherto unknown species is an interesting result. Twelve species were described by Malicky and Mey (2020) as a first part and, in this article, we provide species descriptions of seven further species as a second part. The Chin Hills are a somewhat isolated mountain range and the occurrence of endemic species and their detection was and, is, of high probability. Some of the described species are perhaps true endemics, while others may occur with further populations north or south of the Chin Hills. Further collecting in Myanmar is necessary to determine the biogeographic status of the new taxa.

Species/taxon
West-east longitudinal gradient 85°-95°95°-98°98°-108°P seudoleptonema quinquefasciatum (Martynov, 1935) I, N Y L, T, V Diplectrona aumel Malicky & Mey, 2020* Diplectrona aurovittata Ulmer, 1906 A, N S Ma, T Diplectrona burha Schmid, 1961 I, N T, V Diplectrona harpyia Malicky & Chantaramongkol, 1992 T Diplectrona hermione Malicky & Chantaramongkol, 1992 T, Ma Diplectrona flavospilota Mey, 1998V Diplectrona sanguana Kimmins, 1964 N Cheumatopsyche charites Malicky & Chantaramongkol, 1997 T, V Cheumatopsyche chryseis Malicky & Chantaramongkol, 1997 The Trichoptera of Myanmar were summarised in a first, annotated check-list by Wity et al. (2015) providing data for a total of 227 species. The investigations of the present authors yielded another 77 species, previously unrecorded from the country or herein established as new taxa. This brings the number of species records from Myanmar to 304. However, this number will certainly increase with future collection efforts, such as the initiative of P. Laudee from Thailand. After Kambaiti in the Kachin State, the NTNP in the Chin State represents now the second location of a more thorough inventory of Trichoptera in Myanmar. It will hopefully be followed by further studies in coming years, a demanding task with regard to the shrinking areas of natural habitats in Myanmar and elsewhere in south-east Asia.  (1), Plenitentoria (2) and Brevitentoria (4). Species with an asterix (*) may occur in more than one column.