Touranella srisonchaii Likhitrakarn, 2025

Touranella srisonchaii Likhitrakarn sp. nov.

Figs 7 View Figure 7 , 8 View Figure 8 , 9 View Figure 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 GoogleMaps .

Paratypes: • 25 ♂, 42 ♀ ( CUMZ -PD 0032 ), same locality, together with holotype, leg. R. Srisonchai. GoogleMaps

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 View Figure 7 ). It differs from T. champasak by having process d at the mid-length of the solenophore (Figs 8 View Figure 8 , 9 View Figure 9 ) (vs absent); a more erect and thicker solenophore (Figs 8 View Figure 8 , 9 View Figure 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 View Figure 8 , 9 View Figure 9 ) (vs a suberect gonopodal solenophore with a slender and acute process d, Figs 5 View Figure 5 , 6 View Figure 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 View Figure 7 ); 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 View Figure 7 ).

Clypeolabral region and vertex sparsely setose, epicranial suture distinct. Antennae moderately long (Fig. 7 A, B View Figure 7 ), 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 View Figure 7 ).

Tegument smooth and shining, prozona finely shagreened, metaterga finely rugulose (Fig. 7 A – F, H View Figure 7 ); surface below paraterga finely microgranulate (Fig. 7 C, E, F View Figure 7 ). 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 View Figure 7 ), 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 View Figure 7 ). Following rings with evident lateral bulges, not produced past rear tergal margin, broader on pore-bearing rings (Fig. 7 B, D, F View Figure 7 ). 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 View Figure 7 ).

Transverse metatergal sulci usually distinct (Fig. 7 B – F, H View Figure 7 ), 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 View Figure 7 ). 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 View Figure 7 ).

Epiproct (Fig. 7 F – H View Figure 7 ) 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 View Figure 7 ).

Sterna sparsely setose, without modifications (Fig. 7 G View Figure 7 ); an entire, rather short, rounded, linguiform, setose, sternal lobe between ♂ coxae 4 (Fig. 7 I, J View Figure 7 ). 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 View Figure 8 , 9 View Figure 9 ). Coxite slightly curved caudally, rather densely setose distodorsally (Figs 8 A, B View Figure 8 , 9 A, B View Figure 9 ). Prefemoral part (pfe) densely setose, ~ 1 / 3 as long as acropodite (femoral + postfemoral parts) (Figs 8 A, B View Figure 8 , 9 A, B View Figure 9 ). 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 View Figure 8 , 9 A, B View Figure 9 ). Solenophore (sph) long, stout, suberect, with a clear lateral shoulder, sheathing most of solenomere (sl) (Figs 8 A, B View Figure 8 , 9 A – D View Figure 9 ). Lamina lateralis (ll) well-developed, strongly twisted, and lamina medialis (lm) suberect (Figs 8 B View Figure 8 , 9 D, E View Figure 9 ). Tip of lamina lateralis a broad, expanded, apical lamina with three small denticles (Figs 8 A, B View Figure 8 , 9 A – G View Figure 9 ), at halfway bearing a large, long, slightly curved, subtruncate tip process d, this rising distal to lamina lateralis (Figs 8 A, B View Figure 8 , 9 A – G View Figure 9 ).

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.