Tylopus tropicalis 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 tropicalis

description: Tylopus tropicalis Likhitrakarn, n. sp.
(Figs 1-3)
urn:lsid:zoobank.org:act: 659DCAD1-0B29-4445-8774-4DA522FC15CC
TYPE MATERIAL. — Holotype. China • ♂; Yunnan Province, Xishuangbanna Dai Autonomous Prefecture, Xishuangbanna Tropical Botanical Garden; c. 600 m a.s.l.; 21°55’03.1”N, 101°16’17.2”E; 26.XI.2016; C. Sutcharit leg.; CUMZ-PD0028.
ETYMOLOGY. — The species is so named to emphasize the tropical forest habitat of the type locality where the holotype was collected; adjective.
DIAGNOSIS. — The new species seems to be particularly similar to both T. spinisterna Nguyen, 2012 from Vietnam and T. schawaller i Golovatch, 2013 from China, especially in its gonopodal conformation. Indeed, these species share a stout, high and suberect process h. However, the new species differs from T. spinisterna by having the solenomere more strongly twisted and longer than process h (Figs 2; 3A, B); the caudal corner of midbody paraterga is pointed and more strongly protruded behind (Fig. 1D), while midbody sterna show no modifications (Fig. 1G). The new species differs from T. schawalleri in having longer antennae, in the shape of sternal lobes between ♂ coxae 4, coupled with the pleurosternal carinae being complete crests with evident, sharp, caudal denticles produced past the rear tergal margin on rings 2-8 (Fig. 1C), gradually decreasing in size until ring 15 (Fig. 1H) (vs complete crests only on rings 2-7 and gradually decreasing in size until ring 11) and femora 4-12 each with an adenostyle distally on ventral side (Fig. 3D, C) (vs adenostyles absent).
DESCRIPTION
Length c. 20 mm, width of midbody pro- and metazona 1.6 and 2.4 mm, respectively (♂).
Coloration of live animals dark castaneous brown (Fig. 1A), with contrasting light brown calluses of paraterga; venter and legs yellowish brown; coloration of alcohol material after five years of preservation faded to dark brown; calluses of paraterga yellowish brown to pallid, venter and legs light brown to light yellowish (Fig. 1 B-J).
Clypeolabral region and vertex sparsely setose, epicranial suture distinct. Antennae long (Fig 1A), reaching to ring 4 when stretched dorsally. In width, head <ring 3 <ring 4 <collum <ring 2 <5 <6 <7-16 (Fig. 1B), thereafter body gently and gradually tapering. Collum with three transverse rows of strong setae: 3 +3 anterior, 2+ 2 intermediate, and 3+ 3 posterior; a small lateral incision near midway; caudal corner very broadly rounded, paraterga declined ventrad, not produced past rear tergal margin (Fig. 1B, C).
Tegument smooth and shining, prozona finely shagreened, metaterga smooth and leathery, posterior halves often rugulose, surface below paraterga microgranulate (Fig. 1 A-F, H). Postcollum metaterga with two transverse rows of rather long setae: 2 + 2 in anterior and 2+ 2 in posterior row, the latter often abraded, but then readily traceable as insertion points. Tergal setae long, strong, slender, about 1/3 metatergal length. Axial line visible both on pro- and metazona. Paraterga strongly developed (Fig. 1B, D, F), subhorizontal, slightly upturned posteriorly, always lying high, at upper 1/3 midbody height, but remaining below dorsum; anterior edge well-developed, mostly regularly rounded and narrowly bordered, fused to callus; caudal corner narrowly rounded, extending increasingly past rear tergal margin, especially strongly curved mesad on rings 15-19, posterior edge oblique (Fig. 1D, F); paraterga very thin blunt blades in lateral view, a little thicker only on pore-bearing rings (Fig. 1E). Calluses on paraterga delimited by a sulcus only dorsally. Paraterga 2 broad, lateral edge with an evident incision in anterior 1/3 and a small knob in posterior 1/3. Paraterga 3 and 4 with two small incisions at lateral edge (Fig. 1B), one in anterior 1/3, the other at posterior 1/3; anterior incision particularly evident. Lateral edge of following paraterga with two small incisions, one in anterior 1/3, the other at midway, caudal incision being smaller in pore-bearing rings (Fig. 1D). Ozopores evident, lateral, lying in an ovoid groove at about 1/3 metatergal length in front of posterior edge of metaterga (Fig. 1D, E). Transverse sulcus usually distinct (Fig. 1B, D, F), slightly incomplete on rings 4 and 18, complete and clearly visible on metaterga 5-17, deep, reaching the bases of paraterga, arcuate, ribbed at bottom. Stricture between pro- and metazona rather wide, deep, ribbed at bottom down to base of paraterga (Fig. 1C, D). Pleurosternal carinae complete crests on rings 2-8, thereafter broken into an anterior bulge and a caudal tooth, both growing increasingly reduced until ring 15, thereafter missing (Fig. 1C, E, H).
Epiproct (Fig. 1 F-H) 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. 1G), small setiferous knobs at caudal edge well-separated and evident.
Sterna sparsely setose, without modifications (Fig. 1G); cross-impressions shallow; a single, linguiform, sternal lobe between ♂ coxae 4 (Fig.1I, J). Legs long and slender, midbody ones c. 1.3-1.4 as long as body height (Fig. 3E); femora 5-11 each with a large adenostyle distally on ventral side (Fig. 3D), a smaller adenostyle on each of femora 4 and 12 (Fig. 3C); tarsal brushes present until ring 16 (♂).
Gonopods simple (Figs 2; 3A, B); coxite (cx) a little curved caudad, sparsely setose distoventrally. Prefemorite (pfe) densely setose, as usual, about 1/3 as long as femorite + “postfemoral” part. Femorite (fe) rather slender, expanded distad, slightly curved, showing a mesal groove; lobe l simple; process m evident; solenophore (sph) long and slender, typically coiled, tip subtruncate; process h strongly developed, curved and acute, expanded distad, set higher than solenophore.
KEY TO SPECIES OF TYLOPUS JEEKEL, 1968 CURRENTLY KNOWN TO OCCUR IN CHINA, CHIEFLY BASED ON ♂ CHARACTERS, MODIFIED AFTER GOLOVATCH (2013)
1. Paraterga moderately developed, never pointed beak-like caudally, ratio of ♂ midbody prozonite to metazonite width <1:1.2 .............................................................................................................................................. 2
— Paraterga relatively well-developed (Fig. 1B, D), pointed beak-like caudally, radio of ♂ midbody prozonite to metazonite width> 1:1.2 ............................................................................................................................ 5
2. Coloration pale yellowish brown. Gonopod relatively simple, process h poorly developed, no additional outgrowths near base. ................................................................................................ T. sinensis Golovatch, 1995
— Coloration light brown to blackish brown. Gonopods more complex .......................................................... 3
3. Body smaller: length 17-20 mm. Coloration light brown. ♂ tarsal brushes present until ring 9. Gonopod process h present, hook-shaped and pointed ................................................................. T. uncinatus Golovatch, 2020
— Body larger: length ca 21-30 mm. Coloration light to blackish brown. ♂ tibial and tarsal brushes present until ring 17. Gonopod process h absent or present and disk-shaped ................................................................... 4
4. Body smaller: length 21-23 mm. ♂ prefemora clearly swollen laterally. Gonopod process h present, while solenophore with two characteristic distal spines (a and s) ........................................... T. similis Golovatch, 2014
— Body larger: length ca 30 mm. ♂ prefemora only very faintly bulged laterally. Gonopod process h absent, while solenophore without spines .................................................................................. T. kabaki Golovatch, 2014
5. Gonopod very simple, process h absent .............................................................. T. reductus Golovatch, 2013
— Gonopod process h present (Figs 2; 3A, B) .................................................................................................. 6
6. Body smaller: length 17 mm. Coloration whitish grey with a light brown pattern on pro- and metazona. ♂ legs without adenostyles ........................................................................................ T. schawalleri Golovatch, 2013
— Body larger: length ca 20-28 mm. Coloration otherwise. ♂ legs with adenostyles (Fig. 3C, D) ................... 7
7. Antennae longer, reaching until ring 4 when stretched dorsally. Only ♂ femora with tuberculiform adenostyles (Fig. 3C, D) .................................................................................................. T. tropicalis Likhitrakarn, n. sp.
— Antennae shorter, extending only behind ring 2 or 3 when stretched dorsally. ♂ femora, postfemora, tibiae and tarsi with tuberculiform adenotyles ............................................................................................................. 8
8. Gonopod process h a very sharp tip and shorter than half solenophore height. Pleurosternal carinae present until ring 17 .................................................................................................. T. deharvengi Liu & Luo, 2013
— Gonopod process h stout and higher than half solenophore height. Pleurosternal carinae present until ring 11 ............................................................................................................... T. nigromarginatus Golovatch, 2018
REMARKS ON TYLOPUS SPECIES FROM CHINA
Tylopus sinensis Golovatch, 1995 was the first species of Tylopus to be documented from China. It was so named to emphasize the country of origin (Golovatch 1995).
Seven new species of Tylopus have since been described from China (Golovatch 2013, 2014, 2018, 2020; Liu & Luo 2013). The altitudinal distributions of the Tylopus species in China vary from lowland to high-montane (350-4025 m a.s.l.). All congeners appear to be confined to the southwestern parts of the country (Golovatch & Liu 2020). As a result, presently the fauna comprises nine species currently documented from China, including the above new one.
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 77-80, DOI: 10.5252/zoosystema2025v47a5, http://zenodo.org/record/14886499