Touranella chenla Likhitrakarn 2025, sp. nov.
Touranella chenla Likhitrakarn sp. nov. Figs 4, 5, 6 Type material. Holotype • ♂ (CUMZ - PD 0031), Laos, Champasak Province, Pakse District, Vat Phou, 107 m, 14°50'52.9"N, 105°49'38.8"E, 23.7.2013, leg. Chirasak Sutcharit. Diagnosis. The new species seems to be particularly similar to T. champasak from Bolaven Plateau, Laos, especially in gonopodal structure. Both species share a strongly reduced gonopodal femorite devoid of a femoral process and a distally slightly twisted solenophore (Figs 5, 6). However, the new species differs from T. champasak by having a long, acute process d located around the mid-length of a more clearly erect and thicker solenophore (Figs 5, 6). Additionally, pleurosternal carinae are complete crests with sharp caudal denticles extending beyond the rear tergal margin only on rings 2 and 3, reduced to a rounded caudal crest on rings 4 and 5, and absent thereafter (Fig. 4 C, E) (vs absent on rings 18–19). Moreover, ♂ tarsal brushes are present until ring 8 (vs until ring 16). Description. Length 15.2 mm, width of midbody pro- and metazona 1.1 and 1.3 mm, respectively (♂). Coloration of live animals dark brown (Fig. 4 A); legs pale orange, venter and a few basal podomeres pale brown to yellow brown. Coloration in alcohol after 11 years of preservation faded to pale brown; antennae and epiproct pale brown to pallid, venter and podomeres pallid (Fig. 4 B – J). Clypeolabral region and vertex sparsely setose, epicranial suture distinct. Antennae long (Fig. 4 A), reaching until ring 5 when stretched dorsally. In width, ring 4 <3 <2 <collum <ring 5 <6 <7 <head <8–17, thereafter body gently and gradually tapering towards telson. Collum with three transverse rows of setae: 3 + 3 anterior, 2 + 2 intermediate, and 3 + 3 posterior; caudal corner very narrowly rounded, slightly declined ventrally, not produced past rear tergal margin (Fig. 4 A – C). Tegument smooth and shining, prozona finely shagreened, metaterga nearly smooth, faintly rugulose and leathery (Fig. 4 B – F, H). Postcollum metaterga each with two transverse rows of setae: 2 + 2 anterior and 2 + 2 posterior, traceable at least as insertion points when setae broken off. Tergal setae simple, slender, short, ~ 1 / 3 metatergal length (Fig. 4 F). Axial line well visible on metazona, traceable also on prozona. Paraterga weak (Fig. 4 A – F, H), lying at ~ 1 / 2 midbody height, slightly upturned, anterior edge rounded and narrowly bordered; caudal corner very narrowly rounded on rings 2–4, not produced past rear tergal margin; almost missing on following rings; pore-bearing rings with evident lateral bulges (Fig. 4 B, D). Ozopores evident, lateral, each lying in an ovoid groove at ~ 1 / 3 metatergal length in front of posterior edge of metaterga (Fig. 4 C, E, H). Transverse metatergal sulci complete on rings 5–16, incomplete on ring 17, very narrow, shallow, not reaching the bases of paraterga, at most faintly beaded at bottom (Fig. 4 B – F, H). Stricture between pro- and metazona wide, deep, clearly ribbed at bottom down to base of paraterga (Fig. 4 B – F, H). Pleurosternal carinae complete crests with a very sharp median tooth on rings 2 and 3, reduced to a rounded caudal crest on rings 4 and 5, thereafter missing (Fig. 4 C, E, H). Epiproct (Fig. 4 F – H) conical, flattened dorsoventrally, with two small, rounded, apical papillae; tip subtruncate; lateral pre-apical papillae very small, lying close to tip. Hypoproct roundly subtriangular, setigerous knobs at caudal edge small and well-separated (Fig. 4 G). Sterna sparsely setose, without modifications; an entire, high, rounded, linguiform, setose sternal lobe between ♂ coxae 4 (Fig. 4 I, J). Legs long, midbody legs 1.2–1.4 × as long as body height, prefemora without modifications, ♂ tarsal brushes present until ring 8. Gonopods simple, slim and suberect (Figs 5, 6). Coxite slightly curved caudad, densely setose distodorsally (Figs 5 A, B, 6 A, B, D). Prefemoral part (= prefemorite, pfe) as usual, densely setose, ~ 3.5 × shorter than acropodite (femoral + postfemoral parts) (Figs 5 A, B, 6 A – C). Femorite (fe) short, with a strong, long, flagelliform solenomere (sl) twisted distad and with a strong, oblique, lateral sulcus demarcating a postfemoral part (Figs 5 A, B, 6 A – C). Solenophore (sph) long, slightly twisted distad, sheathing most of solenomere (sl), slightly curved caudad (Figs 5 A, B, 6 A – D). Solenophore consisting of a well-developed lamina lateralis (ll) and a smaller lamina medialis (lm) (Figs 5 B, 6 B, C). Tip of lamina medialis subtruncate (Figs 5 B, 6 B), tip of lamina lateralis subrectangular with a long, slender, curved, nearly pointed process d (d), this rising distal to lamina lateralis (Figs 5 A, B, 6 A – D). Both supporting a long and flagelliform solenomere. Distribution. Known only from the type locality, apparently endemic to the southern part of Laos. Etymology. The species epithet chenla refers to the ancient kingdom of Chenla, a powerful kingdom that thrived from approximately 550 to 802 AD across the present-day territories of Thailand, Laos, Cambodia, and Vietnam. The naming also reflects the historical connection between the Chenla era and the construction of the Vat Phou temple complex in Champasak Province, Laos, where the species was discovered (Wikipedia 2025 a, b). This new species so named pays tribute to the rich cultural and historical heritage of the region. Remarks. The newly described species was discovered in the vicinity of Vat Phou, Champasak Province, Laos. This ruined Khmer Hindu temple complex, recognized as a UNESCO World Heritage Site, is situated amidst the lush landscapes of Southeast Asia, providing an intriguing backdrop for biodiversity exploration.
Institutions
- Royal Society (GB)
- Chulalongkorn University (TH)
- Maejo University (TH)
- The Royal College Of Anesthesiologists Of Thailand (TH)
- Severtsov Institute of Ecology and Evolution (RU)
- National University of Laos (LA)
Publication Details
- Journal
- Zenodo (CERN European Organization for Nuclear Research)
- Published
- 2025-05-16
- DOI
- https://doi.org/10.5281/zenodo.15442239
- Primary Topic
- Diatoms and Algae Research
- Type
- article
- Field-Weighted Citation Impact
- 0.00