Tylopus namnonensis Likhitrakarn 2025, n. sp.
Creators: name: Josiane, Natdanai Likhitrakarn
name: Sergei, Josiane Lips
name: Golovatch, Sergei I.
name: Somsak, Ekgachai Jeratthitikul
name: Chirasak, Somsak Panha
name: Sutcharit, Chirasak
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Polydesmida
Paradoxosomatidae
Tylopus
Tylopus namnonensis

description: Tylopus namnonensis Likhitrakarn, n. sp.
(Figs 4-6)
urn:lsid:zoobank.org:act: 53AC6D84-909A-4641-A7CF-0B5ED574A251
TYPE MATERIAL. — Holotype. Laos • ♂; Khammouane Province, Konglor, Tham Nam Non; 175 m a.s.l.; 18°01’44”N, 104°41’26”E; 28.II.2023; J. Lips leg.; CUMZ-27205.
Paratype. Laos • 1 ♀; same data as the holotype; CUMZ-27205.
ETYMOLOGY. — To emphasize Nam Non cave, the type locality, one of the biggest caves in Khammouane Province; adjective.
DIAGNOSIS. — This new species closely resembles T. dorsalis Likhitrakarn, Golovatch & Panha, 2016, particularly in gonopod conformation. However, this new species is distinguished by the metaterga being roughly microgranulate (vs smooth), the distal position of process x on the solenophore (vs median), the pleurosternal carinae in ♂ extending to ring 13 (vs 16), and the tarsal brushes in ♂ present until ring 12 (vs 6).
DESCRIPTION
Length 22.5 mm (♂), 29.3 mm (♀), width of midbody proand metazona 2.2 and 2.8 mm (♂) or 2.7 and 3.5 mm (♀), respectively.
Coloration of live animals light brown (Fig. 4B), with contrasting dark brown to blackish collar covering both pro- and metazona, head, collum, rings 2 and 3 dark brown to blackish, antennae and epiproct light brown, antennomere 7 dark brown, paraterga, venter and legs yellowish brown; coloration of alcohol material after one year of preservation dark brown; paraterga, legs, antennae and epiproct light yellow-brown, antennomere 7 dark brown, head and collum brownish, following terga with a light brown triangle and a blackish collar covering both pro- and metazona (Fig. 5 A-F), venter and a few basal podomeres light yellowish to pallid (Fig. 5A, B, E-G).
Clypeolabral region and vertex rather densely setose, epicranial suture distinct. Antennae relatively short (Fig. 5A, B), reaching to body ring 3 when stretched dorsally (♂, ♀). In width, head <ring 3 <4 <collum <ring 2 <5 <6 <7-16 (♂, ♀), thereafter body gently and gradually tapering towards telson. Collum with three transverse rows of strong setae: 4+4 anterior, 1+ 1 intermediate, and 4+ 4 posterior; a small, lateral, setigerous incision near midway; caudal corner very broadly rounded, paraterga declined ventrad, not produced past rear tergal margin (Fig. 5A, B).
Tegument dull and shining, prozona finely shagreened, metaterga often roughly microgranulate and rugulose, leathery, surface below paraterga more delicately, but still sufficiently clearly microgranulate and rugulose (Fig. 5 A-F). Postcollum metaterga with two transverse rows of rather long setae: 2 + 2 in anterior and 3+ 3 in posterior row, the latter often abraded, but then readily traceable as insertion points. Tergal setae long, strong, slender, about 1/4 metatergal length. Axial line well visible on metazona, traceable also on prozona. Paraterga strongly developed (Fig. 5 A-G), especially so in ♂, set rather high (at upper 1/3 body height), slightly upturned, but lying below dorsum; anterior edge broadly rounded and narrowly bordered, fused to callus; caudal corner rather narrowly rounded, extending increasingly past rear tergal margin, especially well curved mesad on rings 16-19, posterior edge oblique (Fig. 5F, G); paraterga very thin blunt blades in lateral view, a little thicker only on pore-bearing rings (Fig. 5D). Calluses on paraterga delimited by a sulcus both dorsally and ventrally. Paraterga 2 broad, horizontal, anterior edge angular, lateral edge with three evident incisions: two in anterior 1/3, one at midway, and the smallest one near a very broadly rounded caudal corner. Paraterga 3 and 4 each with two small incisions at lateral edge (Fig. 5A), one in anterior 1/3, the other at posterior 1/3. Following paraterga each with one evident lateral incision in anterior 1/3 (Fig. 5C). Ozopores evident, lateral, lying in an ovoid groove at about 1/3 metatergal length in front of posterior edge of metaterga (Fig. 5B, D). Transverse sulcus usually distinct (Fig. 5A, C, F), slightly incomplete on ring 19, complete and clearly visible on metaterga 5-18, narrow, deep, reaching the bases of paraterga, ribbed at bottom. Stricture between pro- and metazona wide, deep, ribbed at bottom down to base of paraterga (Fig. 5A, C, F). Pleurosternal carinae complete crests on rings 2-4 (♂, ♀), clearly increasing in size on rings 5-7, thereafter broken into an anterior small bulge and a small and sharp caudal tooth, both growing increasingly reduced until ring 13, thereafter missing (♂) (Fig. 5B, D, E), or increasingly reduced and remaining only a small caudal tooth until ring 8, thereafter missing (♀). Epiproct (Fig. 5 EG) conical, flattened dorsoventrally, subtruncate, with two evident apical papillae directed caudally, both pointed at tip; pre-apical papillae small, but evident, lying close to tip. Hypoproct subtrapeziform (Fig. 5G), small setiferous knobs at caudal edge well-separated and evident.
Sterna sparsely setose, without modifications (Fig. 5G); cross-impressions shallow; a large, central, slightly bifid, setose lobe between ♂ coxae 4 (Fig. 5H, I). Legs long and slender, midbody ones c. 1.2-1.4 (♂) or 0.9-1.1 times (♀) as long as body height; prefemora not swollen, legs on rings 6-8 each with a small adenostyle on postfemur and tibia; legs of rings 9-16 each with a small adenostyle on femur, postfemur, tibia and tarsus (Fig. 6E); telopodites particularly densely setose ventrally (Fig. 6E), tarsal brushes present until ring 12.
Gonopods rather simple (Fig. 6 A-D). Prefemorite (pfe) densely setose, about 1/3 as long as femorite + “postfemoral” part. Femorite (fe) slightly curved and stout, with an evident mesal groove and a clear distolateral sulcus demarcating a postfemoral part; lobe l simple (Fig. 6B, C); process h rather short, mediodorsal, flattened, tip rounded and with a small notch (Fig. 6B, C); solenophore (sph) long and slender, typically coiled, expanded distad, flattened and evidently bifid, with process x being elongated, apically rounded and directed forward (Fig. 6A, C, D).
REMARKS
The specimens were collected inside a cave (Fig. 4A), around 500 meters away from the entrance. In the wet season, an underground river takes up all of the gallery. Big trees and a lot of wood remains are carried inside. The specimens were collected on wood debris.Despite formally coming from a cave, this new species seems to be nothing more than a trogloxene.
description: Published as part of Josiane, Natdanai Likhitrakarn, Sergei, Josiane Lips, Golovatch, Sergei I., Somsak, Ekgachai Jeratthitikul, Chirasak, Somsak Panha & Sutcharit, Chirasak, 2025, Three new species of the Oriental millipede genus Tylopus Jeekel, 1968 (Diplopoda, Polydesmida, Paradoxosomatidae) from China and Laos, pp. 75-88 in Zoosystema 47 (5) on pages 80-83, DOI: 10.5252/zoosystema2025v47a5, http://zenodo.org/record/14886499