New species of the genus Trichosetodes Ulmer, 1915 (Trichoptera, Leptoceridae) from Ratanakiri province, Cambodia, based on morphological and molecular data.

Three new species of Trichosetodes, namely T.carmelaesp. nov., T.katiengensissp. nov. and T.ratanakiriensissp. nov. are described and illustrated by male specimens. The male genitalia of T.carmelaesp. nov. can be distinguished from the other 16 species of the genus found in Southeast Asia by the shape of the phallicata. The phallicata of T.carmelaesp. nov. bears a tuft of long hairs in the middle of the dorsal edge. Trichosetodeskatiengensissp. nov. can be distinguished from the other species in Southeast Asia by the shape of the phallicata which is divided into dorsal and ventral branches in lateral view, and T.ratanakiriensissp. nov. by the characters of the left inferior appendage and the shape of segment IX. The posterior end of the left inferior appendage of T.ratanakiriensissp. nov. is not forked and the ventral and lateral views of the posteroventral lobes of segment IX are rounded. Illustrations of male genitalia of Trichosetodeskampongspeuensis Malicky & Kong, 2020 are provided for comparison. The molecular diversity of new Trichosetodes species was analyzed using the mitochondrial large subunit ribosomal rRNA gene region (16S rRNA). In terms of their genetic divergence, T.ratanakiriensissp. nov. and T.kampongspeuensis exhibited remarkable proximity, with only a 1.4% distance. On the contrary, T.carmelaesp. nov. displayed genetic disparity exceeding 6.3% when compared to both T.ratanakiriensissp. nov. and T.kampongspeuensis.

Description of the larva of Macrostemum floridum (Navás 1929) (Trichoptera: Hydropsychidae) and its feeding habits in Kaengkrung National Park, southern Thailand.

A morphological description of the last (fifth) instar larva of Macrostemum floridum (Navás 1929), its life cycle, and feeding habits are provided. The study was conducted along the Khlong Yan Stream in Kaengkrung National Park, southern Thailand. Larval identification was achieved by the metamorphotype method of associating immature stages with the adult. A graph of head capsule widths for all instars is provided. Gut content analysis showed that the main food items were diatoms, green algae, and blue-green algae. The larvae construct fixed retreats and feed as collecting filterers.

Distribution of Ecnomus McLachlan, 1864 (Trichoptera, Ecnomidae) from the Lower Mekong River with a description of Ecnomusstungtrengensis new species.

Background: Trichoptera were surveyed from four different physiographic regions of the Lower Mekong River, including the Northern Highlands, the Khorat Plateau, the Tonle Sap Basin and the Mekong Delta in Myanmar, Laos, Thailand, Cambodia and Vietnam. New information: Twenty-three species of the genus Ecnomus, including a new species, were identified and mapped. Ecnomusmammus Malicky & Chantaramongkol, 1993 is a common species which is found from Tonle Sab Basin and Mekong Delta. Ecnomusalkmene Malicky & Chantaramongkol, 1997, E.volovicus Malicky & Chantaramongkol, 1993 and Ecnomusquordaio Malicky, 1993 are the common species in the area of the Northern Highlands and the Khorat Plateau. Ecnomusplotin Malicky & Laudee 2010 is found in the Mekong Delta. Ecnomustriangularis Sun, 1997 is a new species record for Southeast Asia. In addition, E.stungtrengensis sp. n. is described and illustrated. The male genitalia of E.stungtrengensis sp. n. are clearly different from those of other species in the genus Ecnomus by the shape of superior appendages which are slender and bent downwards distally in lateral view.

Larval morphology, life cycle and nutritional values of Lepidostoma abruptum Banks 1931 (Trichoptera: Lepidostomatidae) from Lower-Hill Evergreen Forests of Southern Thailand.

The larval morphology, life cycle, and nutritional values of Lepidostoma abruptum Banks 1931 are described and discussed. The larval case is rectangular in cross section, made of rectangular pieces of leaf. The larva of L. abruptum shares the morphological characteristics of other Lepidostoma spp. which have been described from different countries and continents. The head capsule widths of 74 specimens were measured and plotted to determine the instars of the larvae. This species is non-seasonal. In addition, the moisture (68.87%) and dry-weight nutritional values of the specimens were determined: protein (49.08%), total fat (27.13%), total dietary fiber (5.9%), omega-3 (0.15%), omega-6 (6.04%), and omega-9 (11.7%). Larvae of this species live in small debris pools dominated with leaf litter and small branches.

Three new species of caddisflies (Trichoptera, Hydroptilidae, Polycentropodidae, Leptoceridae) from Khon Phapheng Waterfall, the Mekong River, Laos.

The Mekong River is a hotspot area for freshwater biodiversity, but caddisfly diversity is largely understudied. Three new species of caddisflies from three different families are described and illustrated from Khon Phapheng Waterfall, the Mekong River, Laos; Orthotrichiachoengthongi Malicky & Laudee, sp. nov. (Hydroptilidae), Pseudoneureclipsiskhonphaphengensis Malicky & Thamsenanupap, sp. nov. (Polycentropodidae), and Setodeskarrilai Malicky & Laudee, sp. nov. Orthotrichiachoengthongi Malicky & Laudee, sp. nov. can be differentiated from the most similar OrthotrichiatritonMalicky 2008 by the specific shape of segment X which is long and tubular, pointed apically and curved inward then immediately upward in dorsal view. Pseudoneureclipsiskhonphaphengensis Malicky & Thamsenanupap, sp. nov. differs from the similar P.kaineus Malicky & Bunlue in Malicky et al. 2004 by the shape of the inferior appendages that are usually broad, almost circular in lateral view. Setodeskarrilai Malicky & Laudee, sp. nov. is mainly different to S.omphale Malicky & Changthong in Malicky et al. 2004 by the distal part of segment X which has a brush-like process.

A new species, Agapetus kaengkrungensis (Trichoptera: Glossosomatidae) from Kaeng Krung National Park, southern Thailand with the distribution map of the genus in Thailand.

The male of a new species of caddisfly, Agapetus kaengkrungensis n. sp. (Glossosomatidae) is described and illustrated from Kaeng Krung National Park, Surat Thani Province, southern Thailand. Agapetus kaengkrungensis n. sp. is distinguished from other species by the characters of segment IX and inferior appendages. The distributions of the Agapetus spp. of Thailand are mapped and discussed.

Description of the final instar larva of Anisocentropus diana Malicky amp; Chantaramongkol 1994 (Trichoptera: Calamoceratidae) in Thailand.

The last instar larval stage of a Southeast Asian species Anisocentropus diana Malicky Chantaramongkol 1994 (Trichoptera: Calamoceratidae) is described and illustrated based on Thai specimens. The larva of A. diana is different from known larvae of the other East Asian species A. kawamurai (Iwata) and A. magnificus (Ulmer) in its reddish-brown head without any patterns, the heads large ventral apotome, and the abdominal gill arrangement.

New species of caddisflies (Trichoptera: Psychomyiidae, Hydropsychidae, Leptoceridae) from Mekong tributaries, Cambodia.

Males of four new species of caddisflies from Kampong Speu and Siem Reap provinces, Cambodia [Psychomyia kimcheangi n. sp. (Psychomyiidae), Macrostemum siemreapensis n. sp. (Hydropsychidae), Leptocerus angkorwatensis n. sp. (Leptoceridae), and Trichosetodes kampongspeuensis n. sp. (Leptoceridae)] are described and illustrated. Psychomyia kimcheangi n. sp. can be distinguished from other species by characters of the inferior appendages. The main body of each inferior appendage has two branches that are separated near its base but are parallel and close together until the end. In Macrostemum siemreapensis n. sp. the dorsal tip of the phallus has no curved hooklet but instead a knot-like protruding structure in ventral view and looped-like structure in dorsal view. Leptocerus angkorwatensis n. sp. can be distinguished from others by the characters of long needled-like preanal appendages. Trichosetodes kampongspeuensis is distinguished from others by the characters of segment IX in ventral view, which is asymmetrical, and inferior appendages that are not divided and asymmetrical.

Four new species of caddisflies (Trichoptera: Polycentropodidae, Psychomyiidae, Hydropsychidae, Odontoceridae) from Khao Nan and Tai Rom Yen National Parks, southern Thailand.

Males of four new species of caddisflies, Polyplectropus hofmaierae n. sp. (Polycentropodidae), Eoneureclipsis chinachotiae n. sp. (Psychomyiidae), Hydropsyche khaonanensis n. sp. (Hydropsychidae), and Lannapsyche tairomyenensis n. sp. (Odontoceridae) are described and illustrated. Polyplectropus hofmaierae n. sp. is distinguished from other species by the shape of the apical end of its inferior appendages and its sharp intermediate appendages. The posterior edges of their inferior appendages run slanting to the ventrodistal point and are densely covered by short and stiff bristles. Eoneureclipsis chinachotiae n. sp. is differentiated by characters of its phallus, as the first two thirds of its length are slender and slightly curved. The distal part has a dorsal hump with a very slender thread on its caudal edge and is slightly bent downward and dilated. Hydropsyche khaonanensis n. sp. can be differentiated from the other species by its phallus, in which the two apicolateral lobes in ventral view have rounded outer edges. Lannapsyche tairomyenensis n. sp. can be separated from the others by characteristics of the dorsal view of segment IX and the harpago of its inferior appendages. Segment IX is triangular with distinctly convex preanal appendages along the posterior edge of this segment, and the harpago and subapical lobes are relatively similar in shape and length.

New species of caddisflies (Trichoptera, Ecnomidae, Polycentropodidae, Psychomyiidae) from Mekong tributaries, Laos.

Four new species of caddisflies are added to the fauna of Mekong River, Laos. Described and illustrated are Ecnomus petchanaae sp. nov. and E. boonsawaengae sp. nov. (Ecnomidae), Polyplectropus proukaewi sp. nov. (Polycentropodidae), and Psychomyia srichanai sp. nov. (Psychomyiidae) from tributaries of the Mekong River, Laos. Ecnomus petchanaae sp. nov. can be distinguished by the characters of the superior appendages, which are slender and club-shaped in lateral view. In E. boonsawaengae sp. nov., the inferior appendages are tubular with a concave incision subapically and truncated apex. Polyplectropus proukaewi sp. nov. has the distal process of the dorsal branch of the inferior appendage close to the base of the inferior appendages and the length of the process is half of inferior appendages. Psychomyia srichanai sp. nov. can be distinguished by the structure of the dorsal branches of the harpagones and apical sclerite. The outer branches of the harpago in the latter species are bifurcated and bent 90° degrees outward, and the inner dorsal branches of harpago are curved outward. The apical sclerite is indiscernible.

Four new species of Rhyacophila Pictet, 1834 (Trichoptera: Rhyacophilidae) from Southeast Asia.

Four new species of genus Rhyacophila are described and illustrated from Thailand and Myanmar, Southeast Asia. Rhyacophila longicaudata sp. n. is in the R. nigrocephala Group; the very long basal segment of each inferior appendage distinguishes it from other related species. Rhyacophila aksornkoaei sp. n. and R. limsakuli sp. n. are in the R. anatina Group: they can be differentiated from other species of the group by the brush-like parameres and presence of a ventral process of the aedeagus in R. aksornkoaei sp. n., and by the rectangular apical segment of each inferior appendage and the hooked parameres in R. limsakuli sp. n.. Rhyacophila kengtungensis is in the R. yishepa Group and is characterized by the subtriangular shape of the preanal appendages in dorsal view and by the very large dorsal appendages of the phallic apparatus.

Two new species of Caddisflies (Trichoptera: Insecta) from Lower-Hill Evergreen Forests of Southern Thailand.

Two new species of caddisflies, Macrostemum nigralatum n. sp. and Anisocentropus tairomyenensis n. sp., are described and figured from lower-hill evergreen forests in southern Thailand. Wings of M. nigralatum are black, which distinguishes the new species from other related species. Anisocentropus tairomyenensis n. sp. is a member of the subgenus Anisomontropus and is characterized by the obvious basal expansion of the preanal appendages.

Five new species of Caddisflies (Trichoptera: Insecta) from Upper Tenasserim Range, Thailand and Myanmar.

Five new species of caddisflies are described from the Upper Tenasserim Range, including Chimarra keawpradubi n. sp., Ecnomus niyomwasi n. sp., Psychomyia pinsuwanae n. sp., Leptocerus suwannarati n. sp., and Setodes lertpongsombatae n. sp., based on distinctive characters of male genitalia. Chimarra keawpradubi n. sp. differs from other Chimarra spp. in ventral aspect of inferior appendages, each of which is rectangular with a bulging process apicoventrally and with an acute apex. The basal part of each inferior appendage is square and the apical part is narrow in E. niyomwasi n. sp., differentiating it from other species in the genus. Psychomyia pinsuwanae n. sp. differs from P. amphiaraos Malicky and Chantaramongkol 1997, a closely similar species, by characters of the inferior appendages; the inner branch of each inferior appendage has a long, straight spine on its inner side. Leptocerus suwannarati n. sp. can be distinguished from other Leptocerus spp. by the processes of segment X, which are long, thin, and symmetrical. Setodes lertpongsombatae differs from other Setodes spp. in characters of segment X, which is deeply divided subapically into two very long saber-like blades in lateral view.

Three new species of Ceraclea Stephens 1829 (Trichoptera: Leptoceridae) from Southeast Asia.

Three new species of Ceraclea (Leptoceridae) from Southeast Asia are described and illustrated: Ceraclea (Athripsodina) trisdikooni n. sp. from Myanmar, C. (A.) thongnooi n. sp. from Thailand and Myanmar and C. (A.) thongpongi n. sp. from Laos. Ceraclea trisdikooni n. sp. is distinguished from other species by its inferior appendages recurved ventrad nearly 180° apically. The apex of the basal segment of each inferior appendage is more pointed. In ventral view, each inferior appendage of the new species has an obvious basoventral lobe with numerous long setae. Ceraclea thongnooi n. sp. is distinguished from those by inferior appendages that are each shaped like a seahorse head both in lateral view and ventral view. Ceraclea thongpongi n. sp. is distinguished from other species by the rectangular preanal appendages. In dorsal view, the apical end of segment X is oval and notched apically; in ventral view, the subapicodorsal lobe of each inferior appendage is rounded and straight.

Pseudoleptonema tansoongnerni new species (Hydropsychidae: Trichoptera) with species list of Trichoptera from Li Phi Falls, Mekong River, southern Laos.

A new species named Pseudoleptonema tansoongnerni n. sp. is presented along with a list of Trichoptera from Li Phi falls, Mekong River, southern Laos. Pseudoleptonema tansoongnerni n. sp. is described and figured based on adult males and females. It is distinguished from the others by its forewing pattern and color, which is yellowish brown.

Three new species of Leptoceridae Leach 1815 (Insecta: Trichoptera) from Shan State, Myanmar.

Three new species of Leptoceridae, including Ceraclea satasookae n. sp., Setodes siribumrungsukhai n. sp., and S. salweenensis n. sp. are described and figured from Shan State, Myanmar. Twenty-two species of Leptoceridae were found and 21 of them are new records to the country.

Limnocentropus kritsaneepaibooni new species (Limnocentropodidae: Trichoptera) from Shan State, Myanmar, with faunistic data for the family.

A new species of Limnocentropus, Limnocentropus kritsaneepaibooni n. sp. from Keng Tung Province, Shan State, Myanmar, is described and figured. Three other, previously described species of Limnocentropus are newly recorded for Myanmar, including L. apollon Malicky 1999, L. sammuanensis Malicky & Chantaramongkol 1989, and L. siribhumensis Malicky & Chantaramongkol 1989, resulting in 7 species of the family found in Myanmar.