Tylopus thunghaihin, Likhitrakarn & Golovatch & Panha, 2016

Likhitrakarn, Natdanai, Golovatch, Sergei I. & Panha, Somsak, 2016, The millipede genus Tylopus Jeekel, 1968 (Diplopoda, Polydesmida, Paradoxosomatidae), with a key and descriptions of eight new species from Indochina, European Journal of Taxonomy 195, pp. 1-47 : 25-29

Tylopus thunghaihin sp. nov.

urn:lsid:zoobank.org:act:D8C75297-3063-4B15-ADA6-D86AD5796B96

Figs 18–20, 26

Diagnosis

The new species seems to be especially similar to T. nodulipes ( Attems, 1953) , but differs in the body tegument being dull, coupled with gonopodal process m smaller, process z high and rounded, and process x pointed.

Etymology

To emphasize the type locality, in Lao “Thung Hai Hin”, commonly translated as the famous Plain of Jars, a noun in apposition.

Material examined

Holotype

LAOS: Ƌ, Plain of Jars , Xieng Khouang, 19°25'50" N, 103°09'15" E, ca 1100 m a.s.l., 26 Nov. 2014, leg. S.I. Golovatch, C. Sutcharit, N. Likhitrakarn ( CUMZ).

Paratype

LAOS: 1 ♀, same data as for holotype ( CUMZ).

Description

MEASUREMENTS AND COLOUR. Length 26.1 (Ƌ) or 26.2 mm (♀), width of midbody pro- and metazonae 2.02 and 3.02 mm (Ƌ) or 2.04 and 3.04 mm (♀), respectively. Live coloration brown black ( Fig. 18A); antennae, paraterga and legs dark brown. Coloration in alcohol after one year of preservation blackish, paraterga dark brown; venter and a few basal podomeres light brown to yellow-brown, legs increasingly darker brown distally ( Fig. 18 B–J).

HEAD. Clypeolabral region and vertex sparsely setose, epicranial suture distinct. Antennae rather short ( Fig. 18A), extending behind body segment 3 (Ƌ) or 2 (♀) when stretched dorsally. In width, head <segment 3 <4 <5 <collum <segment 2 <6–16 (Ƌ, ♀); thereafter body gently and gradually tapering. Collum with three transverse rows of setae: 4+4 anterior, 1+1 intermediate and 3+3 posterior; with a small lateral incision near midway ( Fig. 18B, D); caudal corner of paraterga very broadly rounded, declined ventrad, not surpassing rear tergal margin.

BODY. Tegument dull, shining, prozonae finely shagreened; metaterga often roughly microgranulate and rugulose, leathery; surface below paraterga more delicately, but still sufficiently clearly microgranulate and rugulose ( Fig. 18 A–F, H). Metaterga with two transverse rows of small setigerous cones: 2+ 2 in anterior (pre-sulcus) row and 3+3 setae usually borne on low, oblong, rounded tubercles in posterior (post-sulcus) row, except for metaterga 17–19, these latter bearing 3(2)+3(2) setae in anterior row and 4+ 4 in posterior row. Tergal setae simple, slender, often abraded, about as long as 1/3 of metazonite.Axial line visible both on pro- and metazonae. Paraterga strongly developed ( Fig. 18B, D, F), especially so in Ƌ, set high (at upper ¼ of body height), anterior edge rounded and narrowly bordered, fused to callus; caudal corner very narrowly rounded, extending increasingly behind rear tergal margin, posterior edge slightly oblique. Calluses on paraterga delimited by a sulcus only dorsally. Paratega 2 broad, anterior edge angular, lateral edge with three evident incisions. Lateral edge of following paraterga with a clear incision in anterior 1/3 ( Fig. 18B, D, F). Paraterga 16–19 with caudal corner extending increasingly caudally, tip clearly curved mesad ( Fig. 18F). Ozopores evident, lateral, lying in an ovoid groove at about 1/ 3 in front of posterior edge of metaterga. Transverse sulcus distinct ( Fig. 18B, D, F), slightly incomplete on segments 4 and 18, complete on segments 5–17, narrow, wave-shaped, rather deep, not reaching bases of paraterga, ribbed at bottom. Stricture between pro- and metazonae evident, wide, deep, ribbed at bottom down to base of paraterga ( Fig. 18 B–G). Pleurosternal carinae complete crests with a sharp caudal tooth on segments 2–4 (Ƌ, ♀), increasingly reduced to a front bulge and a caudal tooth until segment 7, retained only as a sharp caudal tooth until segment 16, thereafter missing (Ƌ), or increasingly reduced and remaining only a sharp caudal tooth until segment 15, thereafter missing (♀) ( Fig. 18C, E, H). Epiproct ( Fig. 18 F–H) conical, flattened dorsoventrally, with two evident, rounded, apical papillae; tip subtruncate; lateral pre-apical papillae large, lying close to tip. Hypoproct roundly subtriangular, setigerous knobs at caudal edge small and well-separated ( Fig. 18G).

STERNA. Sparsely setose, with a small, but evident cone caudally near each coxa, rear cones being a little larger than fore ones ( Fig. 19C); cross-impressions shallow; a large, central, slightly bifid, setose lobe between Ƌ coxae 4 ( Fig. 18I – J). Legs long and slender, midbody ones ca 1.2–1.4 (Ƌ) or 1.1–1.2 (♀) as long as body height; legs of Ƌ segments 5–17 with femur showing a field of ventral microgranulations, while postfemur, tibia and tarsus each with 1–3 minute adenostyles (tubercles), prefemora not swollen ( Fig. 19G), Ƌ telopodites with particularly dense short setae ventrally ( Fig. 19G), tarsal brushes present until body segment 8.

GONOPOD. Rather complex ( Figs 19A – B, 20); coxa slightly curved caudad, sparsely setose distoventrally. Femorite slightly curved and stout, with an evident mesal groove and a clear distolateral sulcus demarcating a postfemoral part; process h high, strongly twisted, tip evidently bifid; process m short; process z rather long, sausage-shaped; solenophore (sph) large, strongly coiled, expanded distally, flattened and clearly bifid; process x large, dentiform and pointed dorsally.

Remarks

This species has been found under stones, each specimen located in its own burrow of ca 30 cm long under its own stone and forming a kind of small cavern, all in the Plain of Jars, Laos.