Nagaxytes gracilis Srisonchai, Enghoff & Panha 2018, gen. et sp. 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 gracilis

description: Nagaxytes gracilis Srisonchai, Enghoff & Panha gen. et sp. nov.
urn:lsid:zoobank.org:act:A6CF5E48-B6AF-4FBD-A02D-D07E4DCDD605
Figs 1, 4, 5, 17–21
Diagnosis
Metaterga 4–19 with one row of 2+2 posterior spines (anterior row absent). Similar in this respect to N. acantherpestes gen. et comb. nov., but differs from this species by having paraterga longer; degree of elevation of paraterga higher; sternal lobe between male coxae 4 incompletely bilobed; lamina lateralis long, lamella-like, thin, slender, tip round and directed ventrad.
Etymology
The name is a Latin adjective, referring to the slender lamina lateralis of the gonopod telopodite.
Material examined
Holotype THAILAND: ♂, Kanchanaburi Province, Sai Yok District, Daowadueng Cave, 14°28′23″ N, 98°50′04″ E, ca. 133 m a.s.l., 15 Aug. 2016, ASRU members leg. (CUMZ-pxDGT00090).
Paratypes THAILAND: 7 ♂♂, 21 ♀♀, same data as for holotype (CUMZ-pxDGT00091-118); 1 ♂, 1 ♀, same data as for holotype (ZMUC 00040245).
Further specimens, not paratypes
THAILAND – Kanchanaburi Province, Sai Yok District: 1 ♂, 1 broken ♂, 1 broken ♂ (right gonopod lost), 5 ♀♀, Daowadueng Cave, 14°28′23″ N, 98°50′04″ E, ca. 133 m a.s.l., 8 Sep. 2008, ASRU members leg. (CUMZ); 2 ♂♂, 6 ♀♀, Daowadueng Cave, 14°28′23″ N, 98°50′04″ E, ca. 133 m a.s.l., 11 Jul. 2009, ASRU members leg. (CUMZ); 2 ♂♂, Daowadueng Cave, 14°28′23″ N, 98°50′4″ E, ca. 133 m a.s.l., 12 Oct. 2015, ASRU members leg. (CUMZ); 8 ♂♂, 21 ♀♀, 1 broken ♂, 1 ♂ (right gonopod lost), 1 ♂ fragment (gonopods lost), Wat Tham Phrom Lok Khao Yai, 14°12′15″ N, 99°07′57″ E, ca. 122 m a.s.l., 9 Jul. 2009, ASRU members leg. (CUMZ); 1 ♂, Wat Tham Phrom Lok Khao Yai, 14°12′15″ N, 99°07′57″ E, ca. 122 m a.s.l., 15 Aug. 2016, ASRU members leg. (CUMZ); 1 ♂, Kra Sae Cave, 14°06′05″ N, 99°10′09″ E, ca. 79 m a.s.l., 10 Dec. 2006, ASRU members leg. (CUMZ); 3 ♂♂, 3 broken ♂♂, 1 ♂ (right gonopod lost), 5 ♀♀, Hellfire Pass, 14°21′20″ N, 98°57′09″ E, ca. 216 m a.s.l., 29 Aug. 2011, ASRU members leg. (CUMZ); 2 ♂♂, 2 ♀♀, Hellfire Pass, 14°21′20″ N, 98°57′09″ E, ca. 216 m a.s.l., Aug. 2014, ASRU members leg. (CUMZ); 1 ♂, 1 ♀, Ban Thung Kang Yang, 14°24′17″ N, 98°55′04″ E, ca. 263 m a.s.l., 15 Aug. 2016, ASRU members leg. (CUMZ); 4 ♂♂, 5 ♀♀, Wat Sunantha Wanaram, 14°32′11″ N, 98°49′51″ E, ca. 161 m a.s.l., 17 Aug. 2016, ASRU members leg. (CUMZ); 7 ♂♂, 6 ♀♀, Wat Phuttha Vimooddhi Wanaram (Wat Tham Phu Mood), 14°18′07″ N, 98°59′27″ E, ca. 213 m a.s.l., 17 Aug. 2016, ASRU members leg. (CUMZ).
Description
SIZE. Length 30–33 mm (male), 35–38 mm (female); width of midbody metazona ca. 2.2 mm (male), 3.1 mm (female). Width of head <collum <body ring 2 = 3 = 4 <5–17, thereafter body gradually tapering towards telson.
COLOUR (Fig. 17A–B). Specimens in life with body pinkish brown; paraterga vivid pink or reddish pink; collum, prozona, metaterga, surface below paraterga pinkish brown; head, antennae (except whitish distal part of antennomere 7 and antennomere 8) sterna and legs brown; a few basal podomeres whitish brown; epiproct pink. Colour in alcohol: after 3–9 years changed to pale brown; head, collum, metaterga, surface below paraterga, sterna, epiproct pale brown or whitish brown; paraterga brownish white.
COLLUM (Fig. 18A). With three transverse rows of setae/tubercles and spines, 3+3 setae/tubercles in anterior row, 1+1 setae/tubercles in intermediate row (tubercles small) and 2+2 spines in posterior row; paraterga of collum long and broad, elevated at ca. 40°–45° (male) 35°–40° (female), directed caudolaterad, with 2 conspicuous notches at lateral margin.
ANTENNAE (Fig. 18D). Moderately long and slender, reaching to body ring 5 or 6 (male) and 4 or 5 (female) when stretched dorsally.
TEGUMENT. Quite shiny. Stricture between prozona and metazona shallow, wide.
METATERGA (Fig. 18A–C). Metatergum 2 with 1(2)+1(2) anterior tubercles/cones and 2+2 posterior spines; metatergum 3 with 1+1 anterior tubercles (inconspicuous) and 2+2 posterior spines; metaterga 4–19 with 2+2 posterior spines (anterior row absent; lateral spines of posterior row in all rings very long, longer than mesal ones).
PLEUROSTERNAL CARINAE. On body ring 2 long, crest-like; on body rings 3 and 4 small ridges; thereafter missing.
PARATERGA (Figs 18F–G, 19B). Directed caudolaterad on body rings 2–18, elevated at ca. 70° (male) 60°–70° (female), directed increasingly caudad on body ring 19; notch near the tip at lateral margin of body rings 5–7, 9, 10, 12, 13, 15–18 absent on some rings in some specimens.
TELSON (Fig. 19C–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. 19H–J). Cross-impressions quite deep. Sternal lobe between male coxae 4 incompletely bilobed; base broad; tip deeply emarginate; surface near pores swollen.
GONOPODS (Figs 4–5, 20–21). Coxa subequal in length to femur. Cannula long and slender. Telopodite quite long and slender. Prefemoral part ca. half as long as femur. Femur long and slender, slightly enlarged distally. Mesal sulcus conspicuous, deep, wide; lateral sulcus quite deep and very wide. Postfemoral part conspicuous, short. Solenophore well-developed: lamina lateralis long, lamellalike, thin, slender; tip round, directed ventrad: lamina medialis very long; slightly enlarged distally; apically fringed with several small spines; tip directed mesoventrad. Solenomere long and slender, tip directed ventrad.
Distribution and habitat
Nagaxytes gracilis gen. et sp. nov. is known only from Sai Yok District, Kanchanaburi Province. All specimens were collected on humid rocks, superficial tree roots and litter in limestone habitats. It lives in the same habitat with D. purpurosea, D. golovatchi Srisonchai, Enghoff & Panha, 2018 and N. erecta gen. et sp. nov. (q.v.). The new species occurs in a narrow distribution area along the huge limestone range which is entirely contained within Sai Yok District. We thus consider this species to be endemic to Kanchanaburi Province, Thailand.
Remarks
The vivid pink paraterga are probably aposematic. Nagaxytes gracilis gen. et sp. nov. was noticeable in the field by the contrast of its bright pink colour to brown rocks.
There is a variability in the tip of the epiproct: in some specimens subtruncate, in others slightly emarginate.
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 27-34, DOI: 10.5852/ejt.2018.462, http://zenodo.org/record/1467972