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Research Article
New species of caddisflies (Trichoptera, Ecnomidae, Polycentropodidae, Psychomyiidae) from Mekong tributaries, Laos
expand article infoPongsak Laudee‡, Kriengkrai Seetapan§, Chanda Vongsombath|, Hans Malicky
‡ Prince of Songkla University, Surat Thani, Thailand
§ University of Phayao, Phayao, Thailand
| National University of Laos, Vientiane, Laos
¶ Unafiliated, Scheibbs, Austria

Corresponding author: Pongsak Laudee ( pongsak.l@psu.ac.th )

Academic editor: Ana Previšić
© 2020 Pongsak Laudee, Kriengkrai Seetapan, Chanda Vongsombath, Hans Malicky.
This 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.
Citation: Laudee P, Seetapan K, Vongsombath C, Malicky H (2020) New species of caddisflies (Trichoptera, Ecnomidae, Polycentropodidae, Psychomyiidae) from Mekong tributaries, Laos. ZooKeys 962: 1-11. https://doi.org/10.3897/zookeys.962.52759
ZooBank: urn:lsid:zoobank.org:pub:CA7DEA7C-BFEB-4BC8-A598-A802941FD59F
Open Access

Abstract

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.

Keywords

aquatic insects, biodiversity, Oriental Region, taxonomy

Introduction

The Mekong River, with a length of 5,400 km is the 12th longest river in the world and passes through six countries, originating from China, through Myanmar, Laos, Thailand, Laos, Cambodia, and finally Vietnam (Mekong River Commission 2010a, 2010b). Its river basin is among the most diverse riverine systems of the world, where 367 new species were recently found, including 24 new species of fish and 21 new species of amphibians (World Wild Fund 2014). The Mekong River is in the Oriental Region where diversity of Trichoptera is generally high (de Moor and Ivanov 2008), however, so far this aquatic insect order has not been intensively studied along its course.

Trichoptera (or caddiflies), among the holometabolous aquatic insects, are one of the largest groups of aquatic insects contributing to many aspects in an aquatic ecosystem as secondary consumers, tertiary consumers, or predators (Dudgeon 1999). Adult Trichoptera occupy terrestrial or riparian zones along aquatic habitats. The larval stages are exclusively aquatic (Holzenthal et al. 2007). More than 5,854 species of Trichoptera have been described in the Oriental Region (Morse et al. 2019). Moreover, publications in the last 10 years on Trichoptera in the Oriental Region have recorded more than 3,000 species (Morse 2016). There are several important contributions to the knowledge on caddisfly diversity of the Mekong River in Laos, for instance, description of Maesaipsyche mekongensis found in Luang Prabang Province (Mey 2001). Laudee and Malicky (2017) and Malicky and Laudee (2017) described Pseudoleptonema tansoongnerni Malicky & Laudee, 2017, Pseudoneureclipsis arael Malicky & Laudee, 2017, P. hamabiel Malicky & Laudee, 2017, and Setodes marianu Malicky & Laudee, 2017 as new and listed Trichoptera from the Li Phi falls along Mekong River in the southern Laos. Recently, Malicky and Laudee (2019) described 15 new species of caddisflies from tributaries of the Mekong River in Laos.

In this study, we focus on three caddisfly genera in Laos – Ecnomus McLachlan, Polycentropus Curtis, and Psychomyia Latreille. There are eight species of Ecnomus reported from Laos, including E. alkaios Malicky & Chantaramongkol, 1997, E. alkmene Malicky & Chantaramongkol, 1997, E. androgeos Malicky, 1997, E. amphitryon Malicky, 1997, E. volovicus Malicky & Chantaramongkol, 1993, E. caesar Malicky & Chaibu in Malicky et al. 2000, E. dikla Malicky, 2009, and E. thamar Malicky & Laudee in Malicky, 2009 (Malicky 2010; Laudee and Malicky 2017). So far, only two species of Polyplectropus, P. menna Malicky & Chantaramongkol, 1993 and P. ammonios Malicky, 2009, have been recorded in Laos. In Psychomyia, seven species have been found from Laos, including Ps. thienemanni Ulmer, 1951, Ps. chompu Malicky & Chantaramongkol, 1993, Ps. arthit Malicky & Chantaramongkol, 1993, Ps. anteia Malicky, 1997, Ps. andromache Malicky, 1997, Ps. andromeda Malicky, 1997, and Ps. muriel Malicky & Laudee, 2019 (Malicky 2010; Malicky and Laudee 2019).

Considering the overall diversity of the Mekong River and its tributaries and the under-investigated caddisfly fauna of this region, many new species records and descriptions are expected. This article adds four new species from the Mekong River and its tributaries to the list of Trichoptera in Laos.

Materials and methods

Adult caddisfly specimens were collected with a UV pan light trap (12 V, 10 W) operated along streams and the river overnight at the locations indicated below. Collected specimens were preserved in 70% ethanol, and caddisflies were later manually sorted from other insects. For species-level identifications, the male genitalia were observed under a stereomicroscope. For this purpose, the male genitalia from a specimen from each new species were dissected out. Muscle tissue was macerated by heating in 10% KOH at 60 °C for 30–60 minutes and then soaking in a detergent solution. Drawings were initially made in pencil using a compound microscope equipped with a drawing tube and used to produce the final vector graphics in Adobe Illustrator software.

Holotypes and paratypes are stored in 70% ethanol and deposited in Princess Maha Chakri Sirindhorn Natural History Museum, Prince of Songkla University, Hat Yai Campus, Hat Yai District, Songkhla Province, Thailand (PSUNHM). Some paratypes are deposited in the collection of Hans Malicky (CHM), the Clemson University Arthropod Collection (CUAC), and the National Museum, Prague, Czech Republic (NMPC). Terminology for genitalic structures for different genera follows that of Cartwright (1994) for the genus Ecnomus, Schmid (1997) for the genus Psychomyia and Chamorro and Holzenthal (2011) for the genus Polyplectropus.

Systematics

Ecnomus petchanaae Laudee & Malicky, sp. nov.

http://zoobank.org/61596C7B-1396-41B1-9DC1-60E344674F81
Figure 1

Diagnosis

The male genitalia of E. petchanaae sp. nov. are similar to Ecnomus gapit Cartwright, 1994, E. yuleae Cartwright, 1994, E. dares Malicky, 2000, and E. perseis Malicky, 2008 described from Borneo. The superior appendages of all these species, including the new species, are particularly large and the subapical part of the superior appendages is covered by numerous spiny setae. However, E. petchanaae sp. nov. can be distinguished by the shape of its superior appendages, which, in lateral view, are slender and club-shaped, but basally broad in E. gapit, E. yuleae, E. dares, and E. perseis. In addition, in ventral view of the outer surface of the inferior appendages of the new species is crescent-shaped, whereas they are curved and claw-shaped in E. gapit, E. yuleae, E. dares, and E. perseis.

Figure 1. 

Ecnomus petchanaae, sp. nov. Male genitalia. A Segment IX and superior appendages, dorsal B segments IX and superior appendages, left lateral C segment IX and inferior appendages, ventral D phallus tip, ventral. Ter IX = tergum IX, Ste IX = sternum IX, Sup = superior appendage, Inf = inferior appendage.

Description

Adult, male, length of each male forewing 5.6–6.0 mm; color in alcohol of head, thorax, forewings, abdomen, and legs brown. Male genitalia as in Figure 1A–D. Tergum IX somewhat square, anterior margin truncated, posterior margin bilobed in dorsal view (Fig. 1A); trapezoid and rounded anterodorsally in lateral view (Fig. 1B). Sternum IX ovoid in lateral view (Fig. 1B); rectangular with ¼ concave incision posteriorly, bilobed and rounded anteriorly in ventral view (Fig. 1C). Superior appendages long, slender, with expanded base, curved inward posteriorly with numerous long spiny setae subapically in dorsal view (Fig. 1A); in lateral view, superior appendages, relatively large, long, slightly curved upward, bulb-like apically, with numerous spiny setae (Fig. 1B). Inferior appendages tubular, bent inward, beak-like apically in lateral view (Fig. 1B); in ventral view, crescent-shaped, with a submediate knot, overlapping each other subapically (Fig. 1C). Phallus long, tubular, curved upward, pointed apex with dorsal process in lateral view (Fig. 1B); in ventral view, bulb-like, with pointed apex (Fig. 1D).

Type material

Holotype. Male. Laos: Pakse Province: Paksong, Vang Ngao River, 15°11'37"N, 106°06'40"E, elev. 920 m, 7.iv.2019, Pongsak Laudee. (PSUNHM). Paratypes: same data as the holotype, 3 males: 1 male (PSUNHM), 1 male (CHM), 1 male (NMPC).

Etymology

The species epithet honors Mrs Kanchanaluk Petchana, Director of Administration and Strategic Development Division, Prince of Songkla University, Surat Thani Campus.

Ecnomus boonsawaengae Malicky & Vongsombath, sp. nov.

http://zoobank.org/A970D2D6-D505-4A72-B693-D2C6DC131325
Figure 2

Diagnosis

The male genitalia of E. boonsawaengae sp. nov. are similar to E. aktaion Malicky & Chantaramongkol, 1997 and E. uttu Malicky & Chantaramongkol, 1993. In these species, the superior appendages are particularly long and slender with a basoventral process on the superior appendage. However, E. boonsawaengae sp. nov. can be easily distinguished by the shape of the inferior appendages. In lateral view, the inferior appendages are tubular with a subapical concave incision and truncated apex in E. boonsawaengae sp. nov., but in E. aktaion and E. uttu the inferior appendages are somewhat triangular and trapezoidal, respectively, and with a pointed apex. In addition, each inferior appendage in E. boonsawaengae sp. nov. has a process, in ventral view, which is lacking in E. aktaion and E. uttu.

Description

Adult, male, length of each male forewing 4.0 mm; color in alcohol of head, thorax, forewings, abdomen, and legs grayish brown. Male genitalia as in Figure 2A–D. Tergum IX in dorsal view bilobed posteriorly, U-shaped ½ incision anteriorly (Fig. 2A); in lateral view, tergum IX narrow, expanded dorsally (Fig. 2B). Superior appendages tubular, base with lateral lobe, slightly bent apically to form beak-like apex in dorsal view (Fig. 2A); in lateral view, tubular, truncated apically (Fig. 2B). Basoventral projection of superior appendage tubular with setae apically in lateral view. Sternum IX in lateral view chicken-drumstick-like and rounded apically (Fig. 2B); in ventral view, trapezoid, slightly expanded apically, with shallow U-shaped incision anteriorly and shallow V-shaped incision posteriorly (Fig. 2C). In lateral view, the inferior appendages tubular, with concave incision subapically, truncated apex (Fig. 2B); in ventral view, claw-like, with process basodorsally (Fig. 2C). Phallus sickle-like, with lobe mesodosally in lateral view (Fig. 2D).

Figure 2. 

Ecnomus boonsawaengae, sp. nov. Male genitalia. A Segment IX and superior appendages, dorsal B segment IX and superior appendages, left lateral C segment IX and inferior appendages, ventral D phallus, lateral. Ter IX = tergum IX, Ste IX = sternum IX, Sup = superior appendage, Inf=inferior appendage.

Type material

Holotype. Male. Laos: Pakse Province: Paksong, E-Tu Waterfall, 15°11'25"N, 106°06'14"E, elev. 900 m, 7.iv.2019, Pongsak Laudee. (PSUNHM). Paratypes: same data as holotype, 2 males: 1 male (PSUNHM), 1 male (CHM).

Etymology

The species epithet honors Mrs Wasana Boonsawaeng, Vice Dean of Faculty of Science and Industrial Technology, Prince of Songkla University, Surat Thani Campus.

Polyplectropus proukaewi Malicky & Seetapan, sp. nov.

http://zoobank.org/180D25B8-A9AC-4B3D-BE3C-C2D884F460EF
Figure 3

Diagnosis

The male genitalia of P. proukaewi sp. nov. are similar to those of P. daimong Oláh & Johanson, 2010 from Vietnam. In both species, the dorsal branch of the inferior appendages forms a hooked-like process. However, P. proukaewi sp. nov. can be distinguished by the considerably shorter distance of the distal processes of the dorsal branch of the inferior appendages to their bases compared to P. daimong, in which this distance is considerably longer. Additionally, in the new species, the length of the distal processes in lateral view equals half of the length of inferior appendages, whereas the length of the distal processes equals the length of inferior appendages in P. daimong.

Description

Adult, male, length of each male forewing 6.5–7 mm; color in alcohol of head, thorax, forewings, abdomen, and legs brown. Male genitalia as in Figure 3. Tergum IX triangular, underneath Tergum X in lateral view (Fig. 3B). Sternum IX subtriangular and rounded anteriorly in lateral view (Fig. 3B); in ventral view, hexagonal, with V-shaped incision anteriorly (Fig. 3C). Tergum X hat-shaped in dorsal view (Fig. 3A), B-shaped in lateral view (Fig. 3B). Dorsolateral process of preanal appendages sclerotized, needle-like, straight and horizontal subbasally then recurving upward subapically, distal end pointed in lateral view (Fig. 3B). Mesolateral process of preanal appendages thumb-like, with setae in dorsal view (Fig. 3A); in lateral view leaf-like, with setae (Fig. 3B). Mesoventral processes of preanal appendages short, finger-like, with setae in dorsal view (Fig. 3A); in lateral view, subtriangular, with setae, underneath base of mesolateral processes (Fig. 3B). In lateral view, inferior appendages trapezoidal, with V-shaped incision anteriorly, each dorsal branch of inferior appendages with hook-like processes posterodorsally, half the length of inferior appendages (Fig. 3B). In ventral view, each ventral branch of inferior appendages subtriangular, each dorsal branch of inferior appendages with “bird head-like” dorsal branch of inferior appendages posteriorly (Fig. 3C). In caudal view, inferior appendages oval, with triangular processes dorsally and nose-like process mesally (Fig. 3D)

Figure 3. 

Polyplectropus proukaewi, sp. nov. Male genitalia. A Segment X, dorsal B segments IX–X, left lateral C inferior appendages, ventral D inferior appendages, caudal. Ter IX = tergum IX, Ste IX = sternum IX, Ter X = Tergum X, Do Lat = dorsolateral processes of preanal appendages, Me Lat = mesolateral processes of preanal appendages, Me Ven = mesoventral processes of preanal appendages.

Type material

Holotype. Male. Laos: Pakse Province: Paksong, Vang Ngao River, 15°11'37"N, 106°06'40"E, elev. 920 m, 7.iv.2019, Pongsak Laudee. (PSUNHM). Paratypes: same data as holotype, 16 males: 6 males (PSUNHM), 5 males (CHM), 5 males (NMPC).

Etymology

The species epithet honors Dr Nitat Proukaew, Assistant Professor in the Faculty of Science and Industrial Technology, Prince of Songkla University, Surat Thani Campus.

Psychomyia srichanai Laudee & Malicky, sp. nov.

http://zoobank.org/F525EC47-7B79-4FFF-911A-97FD1EC90519
Figure 4

Diagnosis

The male genitalia of Ps. srichanai sp. nov. are similar to those of three other Psychomyia species described from Thailand, Ps. amor Malicky & Chantaramongkol, 1997, Ps. amphiaraos Malicky & Chantaramongkol, 1997 and Ps. monto Malicky & Chantaramongkol, 1993, as well as of Ps. sonlana Oláh & Malicky, 2010 from Vietnam. Differences are mainly seen in the structure of the dorsal branches of the harpagones and apical sclerite. The dorsal branch of each harpago in Ps. srichanai sp. nov. is divided into two branches. The outer branch curves downward and bifurcates apically, whereas the inner branch is long, curved upward, and apically pointed. In Ps. amphiaraos and Ps. monto, the outer dorsal branch does not bifurcate. The outer dorsal branches of the harpagones are also bifurcated in Ps. amor and Ps. sonlana. However, only in Ps. srichanai sp. nov. are they are bent outward at 90°. The apical sclerite is apically pointed and discernable in Ps. amphiaraos, Ps. monto, Ps. amor, and Ps. sonlana, but indiscernible in Ps. srichanai sp. nov.

Description

Length of each male forewing 3.0–4.0 mm; color in alcohol of head, thorax, forewings, abdomen, and legs yellow brown. Male genitalia as in Figure 4. Preanal appendages crescent-shaped, with U-shaped incision inward mediately, with long setae inward medially, rounded apically in dorsal view (Fig. 4A); in lateral view, preanal appendages large, triangular, rounded apically (Fig. 4B). Sternum IX crookneck-squash-shaped, pointed dorsally, truncated apically in lateral view (Fig. 4B). Harpagones crab-claw-shaped; dorsal branch of each harpago divided into two branches, the outer branch curved downward and bifurcated apically, the inner branch long, curved upward, and pointed apically; ventral branch of each harpago triangular, curved dorsally, rounded apically in lateral view (Fig. 4B). In ventral view, outer dorsal branches of harpago tubular, bent outward subapically, bifurcated apically; ventral branches of harpago tubular, rounded apically (Fig. 4C). Phallus long, tubular, bent 90° medially, curved upward subapically, distal apex in lateral view (Fig. 4B).

Figure 4. 

Psychomyia srichanai, sp. nov. Male genitalia. A Segment IX, preanal appendages and harpago, lateral B preanal appendages, dorsal C harpago, ventral. Har = harpago, Pre = preanal appendage, SIX = sternum of segment IX, Pha = phallus.

Type material

Holotype. Male. Laos: Luang Prabang Province: Elephant Camp, Mekong River, 20°01'46"N, 102°13'13"E, elev. 280 m, 2.iii.2019, Pongsak Laudee. (PSUNHM). Paratypes: same data as holotype, 40 males: 10 males (PSUNHM), 10 males (CHM), 10 males (NMPC), 10 males (CUAC).

Etymology

The species epithet honors Prof. Dr Teerapol Srichana, Director of the Research and Development Office, Prince of Songkla University, Hat Yai Campus.

Discussion

Ecnomus petchanaae sp. nov., E. boonsawaengae sp. nov. and P. proukaewi sp. nov. were collected from a stream and waterfall on Bolaven Plateau, southern Laos. Here, forest type is montane evergreen rainforest. The three new species are rhithral species, which live in small streams where the substrate is dominated by boulders and cobblestones (Fig. 5A–C). Along with the eight previously recorded species of Ecnomus, there are now 10 species belonging to this genus are now known in Laos; of these, four species, including the new species, are apparently endemic to the country (Malicky 2010; Laudee and Malicky 2017). Ecnomus species not only occur in rhithron stream zones but also are found in potamon stream zones (Laudee and Malicky 2017). Three species of Polyplectropus, including the new species, are now recorded from Laos. Among these, two species are reported only from Laos (Malicky 2010). Psychomyia srichanai sp. nov. was collected from main river channel of the Mekong River in Luang Prabang Province, northern Laos (Fig. 5D). This is a potamon species that lives in main Mekong River. Psychomyia srichanai sp. nov. is in P. capillata species group according to the charecters of the group as diagnosed by Malicky and Chantaramongkol (1993). In total, eight species of Psychomyia have been reported from Laos, of which four species, including the new species, are reported only from Laos (Malicky 2010).

Figure 5. 

Study sites from Mekong river and its tributaries. A, B E-Tu Waterfall, Paksong, Pakse Province C Vang Ngao River, Paksong, Pakse Province D the Mekong River, Luang Prabang Province.

Acknowledgements

This research is supported by the Thailand Research Fund (TRF), project number DBG 6180021. We thank Assoc. Prof. Dr Seppo Karrila for comments and linguistic assistance. We also thank Dr Manpreet Singh Pandher and an anonymous reviewer for providing very useful suggestions to improve the manuscript.

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