Touranella srisonchaii Likhitrakarn 2025, sp. nov.

Touranella srisonchaii Likhitrakarn sp. nov. Figs 7, 8, 9 Type material. Holotype • ♂ (CUMZ -PD 0032), Laos, Champasak Province, Paksong District, Phu Thevada Hotel, 106 m, 15°10'50.4"N, 106°14'20.17"E, 24.2.2017, leg. R. Srisonchai. Paratypes: • 25 ♂, 42 ♀ (CUMZ -PD 0032), same locality, together with holotype, leg. R. Srisonchai. Diagnosis. Morphologically, in gonopodal structure this new species seems to be especially similar to both T. chenla sp. nov. and T. champasak, but it is distinguished by the uniform black coloration lacking a cingulate pattern (Fig. 7 A – H). It differs from T. champasak by having process d at the mid-length of the solenophore (Figs 8, 9) (vs absent); a more erect and thicker solenophore (Figs 8, 9) (vs slender and curved). T. srisonchaii sp. nov. differs from T. chenla sp. nov. in having ♂ tarsal brushes present until ring 8 (vs until ring 14) and a twisted solenophore with a laminate and subtruncate process d (Figs 8, 9) (vs a suberect gonopodal solenophore with a slender and acute process d, Figs 5, 6). Description. Length 14.8–21.0 (♂) or 14.6–19.8 mm (♀), width of midbody pro- and metazona 1.5–2.3 and 1.8–2.2 mm (♂) or 1.8–2.4 and 2.2–2.6 mm (♀), respectively. Coloration of live animals mostly dark or blackish (Fig. 7 A); head, antennae, paraterga, and epiproct slightly lighter; venter dark brown, legs pale yellowish. Coloration in alcohol after seven years of preservation faded to dark brown or blackish; head, antennae, paraterga, and epiproct dark brown to pale brown; venter pale brown; legs pale yellowish to pallid (Fig. 7 B – J). Clypeolabral region and vertex sparsely setose, epicranial suture distinct. Antennae moderately long (Fig. 7 A, B), reaching until body ring 4 (♂, ♀) when stretched dorsally. Head in width <collum <ring 3 <4 <2 <5–16 (♂, ♀); thereafter body gently and gradually tapering towards telson. Collum with three transverse rows of setae: 3 + 3 anterior, 2 + 2 intermediate, and 4 + 4 posterior; caudal corner very narrowly rounded, slightly declined ventrally, not produced past rear tergal margin (Fig. 7 B, C). Tegument smooth and shining, prozona finely shagreened, metaterga finely rugulose (Fig. 7 A – F, H); surface below paraterga finely microgranulate (Fig. 7 C, E, F). Postcollum metaterga each with two transverse rows of setae: 3 + 3 anterior and 4 + 4 posterior, nearly always abraded, but still traceable as insertion points. Tergal setae simple, slender, short, ~ 1 / 5 metatergal length. Axial line well visible on metazona, traceable also on prozona. Paraterga moderately developed (Fig. 7 A – F, H), slightly upturned, lying at ~ 1 / 2 midbody height. Paraterga 2 subhorizontal, broad in dorsal view, thin in lateral view; shoulders well-developed, slightly rounded and oblique laterally; caudal tip rounded, slightly produced past rear tergal margin (Fig. 7 B, C). Following rings with evident lateral bulges, not produced past rear tergal margin, broader on pore-bearing rings (Fig. 7 B, D, F). Ozopores evident, lateral, each lying in an ovoid groove at ~ 1 / 3 metatergal length in front of posterior edge of metaterga (Fig. 7 C, E, H). Transverse metatergal sulci usually distinct (Fig. 7 B – F, H), incomplete on rings 4 and 19, complete on metaterga 5–17 (♂, ♀), shallow, not reaching the bases of paraterga, at most faintly beaded at bottom. Stricture between pro- and metazona narrow, beaded at bottom down to base of paraterga (Fig. 7 B – E). Pleurosternal carinae complete crests with a sharp caudal tooth on ring 2, reduced to a rounded caudal crest on rings 3 and 4, thereafter missing (♂, ♀) (Fig. 7 C, E, H). Epiproct (Fig. 7 F – H) conical, flattened dorsoventrally, with two small, rounded, apical papillae; tip rounded; lateral pre-apical papillae very small, lying close to tip. Hypoproct roundly subtriangular, setigerous knobs at caudal edge small and well-separated (Fig. 7 G). Sterna sparsely setose, without modifications (Fig. 7 G); an entire, rather short, rounded, linguiform, setose, sternal lobe between ♂ coxae 4 (Fig. 7 I, J). A paramedian pair of evident tubercles in front of gonopodal aperture. Legs moderately long and slender, midbody ones ~ 1.1–1.3 (♂) or 0.9–1.1 × (♀) as long as body height, prefemora without modifications, ♂ tarsal brushes present until ring 14. Gonopods relatively simple and suberect (Figs 8, 9). Coxite slightly curved caudally, rather densely setose distodorsally (Figs 8 A, B, 9 A, B). Prefemoral part (pfe) densely setose, ~ 1 / 3 as long as acropodite (femoral + postfemoral parts) (Figs 8 A, B, 9 A, B). Femorite (fe) rather short, with a medial, strong, long, flagelliform solenomere (sl), strongly twisted distally, and with an oblique lateral sulcus defining a postfemoral part (Figs 8 A, B, 9 A, B). Solenophore (sph) long, stout, suberect, with a clear lateral shoulder, sheathing most of solenomere (sl) (Figs 8 A, B, 9 A – D). Lamina lateralis (ll) well-developed, strongly twisted, and lamina medialis (lm) suberect (Figs 8 B, 9 D, E). Tip of lamina lateralis a broad, expanded, apical lamina with three small denticles (Figs 8 A, B, 9 A – G), at halfway bearing a large, long, slightly curved, subtruncate tip process d, this rising distal to lamina lateralis (Figs 8 A, B, 9 A – G). Distribution. Known only form the type locality, apparently endemic to the southern part of Laos. Etymology. To honor Dr. Ruttapon Srisonchai, diplopodologist at the Faculty of Science of Khon Kaen University, who has not only contributed to the study of millipede taxonomy in Thailand, but also collected the type series of this new species. Remarks. The new species was discovered near Phu Thevada Hotel in the evening following a rainfall, after a full day of collecting. The area surrounding the hotel is a small pine forest situated on a low hill. The rainfall prompted millipedes and land snails to emerge on the ground and tree trunks, facilitating the collection of a significant number of samples. In total, 67 specimens were taken, revealing a male to female ratio of 1: 1.68.