Tylopus moniliformis Likhitrakarn & Golovatch & Panha 2016, sp. nov.

Tylopus moniliformis sp. nov.

urn:lsid:zoobank.org:act: A510843C-08CC-4818-A45F-E35AFDE80E71

Figs 7–9, 26

Diagnosis

Differs from all known congeners by the almost missing paraterga, much like in T. hongkhraiensis sp. nov., coupled with the gonopod structure being similar to that of T. reductus Golovatch, 2013, but it differs in the solenophore being more strongly twisted and thicker.

Etymology

To emphasize the body being strongly bead-shaped, or moniliform; adjective.

Material examined

Holotype

LAOS: ♂, Tad Fane Waterfall, Paksong, Champasak, 15°10'50" N, 106°08'20" E, ca 970 m a.s.l., 20 Jul. 2013, leg. S. Panha, C. Sutcharit, W. Siriwut (CUMZ).

Paratypes

LAOS: 2 ♂♂, 8 ♀♀ (CUMZ); 1 ♂, 1 ♀ (ZMUM ρ3061); 1 ♂, 1 ♀ (ZMUC); 1 ♂, 1 ♀ (NHMW), all same data as for holotype.

Description

MEASUREMENTS AND COLOUR. Length 14–16 (♂) or 16–18 mm (♀), width of midbody pro- and metazonae 0.6–0.9 and 0.9–1.1 mm (♂) or 0.9–1.2 and 1.2–1.3 mm (♀), respectively. Coloration of live animals dark castaneous brown (Fig. 7A); legs light brown, venter and a few basal podomeres light brown to yellow-brown. Coloration of alcohol material after three months of preservation faded to light brown; antennae and epiproct light brown to pallid, venter and a few basal podomeres light brown to pallid (Fig. 7 B–J).

HEAD. Clypeolabral region and vertex sparsely setose, epicranial suture distinct. Antennae moderately long (Fig. 7A), surpassing body segment 5 (♂) or reaching body segment 4 (♀) when stretched dorsally. In width, head <segment 4 <2 = 3 <collum <segment 5 <6–17 (♂, ♀); thereafter body gently and gradually tapering. Collum with three transverse rows of setae: 5+5 anterior, 2+2 intermediate and 1+1 posterior; a very faint marginal incision laterally in posterior 1/3; caudal corner very narrowly rounded, not surpassing rear tergal margin (Fig. 7B – C).

BODY. Tegument smooth and shining, prozonae very finely shagreened, metaterga almost smooth, delicately rugulose, leathery (Fig. 7 B–F, H). Postcollum metaterga with two transverse rows of setae: 2+2 anterior, always abraded, and 1+1 posterior row, setae traceable at least as insertion points. Tergal setae simple, strong, slender, about 1/3 of metatergal length. Axial line visible, but barely traceable on prozonae (♂). Paraterga 2 well-developed (Fig. 7B, C), horizontal, anterior edges protruded anteriorly, fore corner bent ventrad, pointed; lateral edge with two minute incisions in anterior half; caudal corner very narrowly rounded. Paraterga 3 and 4 rounded, expanded laterally, with two minute incisions only in segment 3. Following paraterga virtually missing (♂) or traceable as small, rounded, laterally expanded bulges (♀), in pore-bearing segments with ozopores set at about half of midbody height. Ozopores (Op) evident (Fig. 7E), lateral, lying in an ovoid groove at about 1/3 of metatergal length in front of posterior edge of metaterga. Transverse sulcus usually distinct (Fig. 7 B–F, H), slightly incomplete on segment 3, complete on segments 4–18 (♂) or complete on segments 5–18 (♀), always incomplete on segment 19 (♂, ♀), narrow, not reaching bases of paraterga, at most faintly beaded at bottom. Stricture between pro- and metazonae wide, evidently ribbed at bottom down to base of paraterga (Fig. 7 B– F, H). Pleurosternal carinae complete crests with a sharp caudal tooth on segments 2 and 3, reduced and remaining a sharp caudal tooth on segment 4, thereafter missing (♂) (Fig. 7C), or thereafter increasingly reduced and remaining a front bulge until segment 18 (♀). Epiproct (Fig. 7 F–H) rather short, flattened dorsoventrally, tip subtruncate, subapical lateral papillae small, but visible, lying close to tip. Hypoproct roundly subtriangular, setigerous knobs at caudal edge well-separated and evident.

STERNA. Moderately setose, without modifications; an entire, high, inverted funnel-shaped, sternal lobe each between ♂ coxae 3 and 4 (Fig. 7I – J), lobe being larger between coxae 4. A paramedian pair of evident tubercles in front of gonopod aperture. Legs very long and slender, slightly incrassate in ♂, midbody ones ca 1.5–1.8 (♂) or 1.1–1.4 times (♀) as long as body height, prefemora without modifications, ♂ tarsal brushes absent.

GONOPOD. Very simple (Figs 8, 9); fermorite straight and rather stout, slightly expanded distad, showing a distinct mesal groove, without outgrowths except for a low, sometimes poorly delimited lobe l; solenophore (sph) expanded and flattened, typically coiled, suberect distally, devoid of processes.

Remarks

This species shows the gonopod with lobe l separated from the femorite by a rather indistinct sulcus, the presence of the latter lobe being one of the main characteristics of Tylopus. Since this locality also yielded the holotype of Desmoxytes rhinoceros Likhitrakarn, Golovatch & Panha, 2014 (cf. Likhitrakarn et al. 2014b), Tad Fane Waterfall becomes a site quite important for nature conservation, being the type locality of these two millipede species.