Nagaxytes acantherpestes, gen. et comb. nov.
Creators: name: Ruttapon Srisonchai
name: Henrik Enghoff
name: Natdanai Likhitrakarn
name: Somsak Panha
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Polydesmida
Paradoxosomatidae
Nagaxytes
Nagaxytes acantherpestes

description: Nagaxytes acantherpestes (Golovatch & Enghoff, 1994) gen. et comb. nov.
Figs 2, 6–10
Desmoxytes acantherpestes Golovatch & Enghoff, 1994: 51 –53, figs 21–28.
Desmoxytes acantherpestes – Enghoff 2005: 96. — Decker 2010: 28. — Nguyen & Sierwald 2013: 1240.
Diagnosis
Metaterga 4–19 with one row of 2+2 posterior spines (anterior row absent). Similar in this respect to N. gracilis gen. et sp. nov. but differs from this species by having paraterga shorter; degree of elevation of paraterga lower; sternal lobe between male coxae 4 subtrapeziform; lamina lateralis swollen, stout, short.
Material examined
Holotype THAILAND: ♂, western coast of Siam Gulf (Gulf of Thailand), Hua Hin [Prachuap Khiri Khan Province, Hua Hin District], 8 Aug. 1979, B. Petersen leg. (ZMUC 000101457).
Other material
THAILAND: 2 ♂♂, 1 ♂ (gonopods lost), 1 ♀, Prachuap Khiri Khan Province, Kui Buri District, Hat Kham Subdistrict, Ban Yan Sue, 12°03′12″ N, 99°37′52″ E, ca. 147 m a.s.l., 31 Aug. 2007, ASRU members leg. (CUMZ).
Redescription
SIZE. Length 32–34 mm (male), 36 mm (female); width of midbody metazona ca. 2.2 mm (male), 3.0 mm (female). Width of head <body ring 2 = 3 <collum <4 <5–16, thereafter body gradually tapering towards telson.
COLOUR. Specimens in life brown. Colour in alcohol: after 29 years changed to pale brown; head, antennae, collum, metaterga, surface below paraterga, sterna, epiproct pale brown; paraterga brownish white.
COLLUM (Fig. 7A). With setae in anterior row and intermediate row, spines in posterior row; paraterga of collum elevated at ca. 35–40°, directed caudolaterad, with two conspicuous notches at lateral margin.
ANTENNAE (Fig. 7D). Moderately long and slender, reaching to body ring 5 or 6 (male) and 5 (female) when stretched dorsally.
TEGUMENT. Quite dull. Stricture between prozona and metazona shallow, wide.
METATERGA (Fig. 7A–C). With one or two transverse rows of setae and spines; metatergum 2 with?1+?1 anterior setae (inconspicuous) and 2+2 posterior spines; metaterga 3–19 with 2+2 posterior spines (lateral spines very long).
PLEUROSTERNAL CARINAE. On body ring 2 long, crest-like; on body ring 3 a small ridges; thereafter missing.
PARATERGA (Figs 7F–G, 8B). Directed caudolaterad on body rings 2–18, elevated at ca. 60° (male) 50°– 60° (female), directed increasingly caudad on body ring 19.
TELSON (Fig. 8C–G). Epiproct quite short; tip usually subtruncate (in some specimens slightly emarginate); lateral setiferous tubercles conspicuous, long, digitiform; apical tubercles conspicuous. Hypoproct subtriangular; caudal margin subtriangular, with inconspicuous setiferous tubercles.
STERNA (Fig. 8H–J). Cross-impressions quite deep. Sternal lobe between male coxae 4 swollen, subtrapeziform when seen in caudal view; base broad; tip slightly or deeply emarginate.
GONOPODS (Figs 9, 10). Coxa subequal in length to femur. Cannula long and slender. Telopodite quite long and slender. Prefemoral part ca. ¾ as long as femur. Femur quite long and slender. Mesal sulcus conspicuous, deep, wide; lateral sulcus conspicuous, very deep. Postfemoral part conspicuous, quite short. Solenophore well-developed: lamina lateralis swollen, stout, short, compact: lamina medialis very long; with a swollen base, gradually becoming thinner towards tip; apically fringed with several small spines; tip directed mesoventrad. Solenomere quite long, curved, tip directed ventrad.
Distribution and habitat
This species is known from two locations (Hua Hin and Ban Yan Sue) in Prachuap Khirikhan Province. We believe that the holotype was probably collected from limestone habitats because the type locality (near Hua Hin) lies in a limestone area. Specimens collected by us were from limestone habitats. It has been found crawling on rocks or on leaf litter.
This species is likely to be syntopic with Desmoxytes planata (Pocock, 1895) at Ban Yan Sue; however, we noticed that the habitats of these two species are clearly different. Nagaxytes acantherpestes gen. et comb. nov. lives on the ground or on limestone rocks while D. planata was found on tree trunks near garbage.
Decker (2010) identified one male in NHMG, collected from Thanboke Khorani National Park, Krabi Province (8°23′12″ N, 98°44′16″ E) as D. acantherpestes. This specimen might perhaps be ‘ D.’ gigas Golovatch & Enghoff, 1994 (in the ‘ gigas ’ group) because the location falls in the distribution range for this group in South Thailand whereas Nagaxytes gen. nov. (the ‘ acantherpestes ’ group) is limited to western Thailand. Moreover, Thanboke Khorani National Park and Hua Hin are far apart, about 500 km.
This species is distributed in a narrow area; we regard N. acantherpestes gen. et comb. nov. as endemic to Prachuap Khiri Khan Province, Thailand.
Remarks
In the original description, Golovatch & Enghoff (1994) did not comment on the live colouration of this species. We did not photograph living specimens, but our collector noticed a brown colouration. Golovatch & Enghoff (1994) also described D. acantherpestes as lacking pleurosternal carinae, but after we re-examined the holotype and examined all newly collected specimens, we found the pleurosternal carinae as crest-like on ring 2, as small ridges on ring 3, thereafter absent. There is a variation in the tip of the epiproct which in some specimens is subtruncate, in others slightly emarginate.
On some specimens we found parasitic mites, probably of the genus Leptus Latreille, 1795 (Fig. 6B). The mites infested the millipede on the metaterga. This association reminds us of what Srisonchai et al. (2018) found in Desmoxytes cervina (Pocock, 1895): several engorged Leptus mites attached to the millipede body.
description: Published as part of Ruttapon Srisonchai, Henrik Enghoff, Natdanai Likhitrakarn & Somsak Panha, 2018, A revision of dragon millipedes II: the new genus Nagaxytes gen. nov., with the description of three new species (Diplopoda, Polydesmida, Paradoxosomatidae), pp. 1-44 in European Journal of Taxonomy 462 on pages 11-18, DOI: 10.5852/ejt.2018.462, http://zenodo.org/record/1467972