Epanerchodus jiangxiensis, Liu & Golovatch, 2018

Liu, Weixin & Golovatch, Sergei, 2018, The millipede genus Epanerchodus Attems, 1901 in continental China, with descriptions of seven new cavernicolous species (Diplopoda, Polydesmida, Polydesmidae), Zootaxa 4459 (1), pp. 53-84 : 61-63

Epanerchodus jiangxiensis , new species

Figs 5–7 .

Material examined: Holotype male ( SCAU eJX1-1) from China, Jiangxi Province, Lianhua County, Gaotan Village, Shuilian Dong Cave , 17.X.2013, colls: Mingyi Tian , Weixin Liu , Haomin Yin and Yanjing Wang . Paratypes: 5 males, 8 females ( SCAU eJX1-2), 1 male, 1 female ( ZMUM), same data as the holotype .

Diagnosis: Adults of E. jiangxiensis n. sp. are distinct from other Epanerchodus species by the presence of 4– 5 and 5–6 lateral incisions/denticles at the lateral margin on the poreless and pore-bearing paraterga, respectively vs. 3–4 in all other continental Chinese Epanerchodus .

Several polydesmid species from Japan (mainly in caves in Kyushu and Shikoku) that formerly composed the genus Prionomatis Miyosi, 1956 are known to show abundant lateral incisions on the paraterga (> 4) and densely setose metaterga. Based to gonopodal structure alone, Prionomatis has since been synonymized with Epanerchodus ( Golovatch 1991) . The new species differs readily from any of the ex- Prionomatis by lacking tergal setae and in the gonopod featuring an unusually prominent hairy pulvillus.

Description: Lengths of both sexes ca 22–25 mm, widths of pro- and metazonae 1.8–2.0 and 3.6–4.0 mm.

Coloration: in alcohol generally pallid to light yellowish. Mouthparts light grey-brown and gonopodal telopodites yellowish ( Fig. 6 ). Body: Adults with 20 rings. Width: head << collum <ring 3 <2 = 4 <5–12, thereafter body gradually tapering posteriorly towards telson. Head: only clypeus densely pilose, vertex smooth, epicranial suture conspicuous ( Fig. 5A ). Antennae long and slender, reaching past posterior margin of ring 4 when extended posteriorly, slightly clavate ( Figs 5A–C ). Exoskeleton: Collum inverted-subtrapeziform, with a faint lateral incision on each side. Paraterga broad ( Fig. 5 ), midbody paraterga extend metatergite to ca 2.0x width of prozonite. Paraterga on collum and rings 2–6 clearly upturned dorsally above a faintly convex dorsum, other paraterga flat ( Fig. 5 ). Caudolateral corners of paraterga clearly projecting posteriorly past tergal margin and strongly acute on rings 16–19. Integument shining, translucent, prozonae very delicately alveolate. Limbus regularly denticulate. Constriction between pro- and metazonae narrow and shallow. Metatergal sculpture faint, with three irregular transverse rows of setigerous, polygonal bosses. Sulcus between front and middle rows of setae a little deeper than that between middle and caudal rows. Tergal setae very short, sometimes present only on collum and ring 19. Paraterga 2–4 with three obvious incisions at lateral margin, thereafter poreless and pore-bearing paraterga with 4– 5 and 5–6 faint incisions at lateral margin, respectively; no visible setae at incisions ( Figs 5B, D, F ). Pore formula normal: 5, 7, 9, 10, 12, 13, 15–19, ozopores evident, dorsal, clearly set off from lateral margin and located between last and penultimate marginal incisions. Epiproct short, conical, pre-apical lateral papillae small. Hypoproct subtrapeziform, with two setigerous papillae. Pleurosternal carinae small, present only on ring 2. Sterna sparsely setose, cross-shaped impressions deep ( Figs 5A, E ). Legs long and slender, about 2.0–2.2 (males) or 1.5–1.6 (females) times as long as body ring height, without sphaerotrichomes or sternal cones, prefemora not bulging laterally. Gonopods: subfalcate ( Figs 6–7 ). Prefemur densely setose and nearly half the length of telopodite, with a clear groove/gutter (g) in mesal view. Femorite with a large, subcircular, dorsal lobe (k). Endomere (en) tip unciform, longer than a simple spiniform exomere (ex). A prominent digitiform process (p) at base of, and about half as long as, en. Seminal groove (sg) starting mesally and distally recurved laterad at base of ex and p, then laterobasad to run into an accessory seminal chamber, the latter opening on a hairy pulvillus.

Notes: Based on the long, slender antennae and legs, and a depigmented cuticle, the species is most likely a troglobite. The discovery of E. jiangxiensis n. sp. in a cave in Jiangxi, which is far from southern Japan where presumably the most similar congeners occur (= ex- Prionomatis ), is very interesting biogeographically.

Etymology: To emphasize the location of the type locality in the Jiangxi Province; masculine adjective.

Figures

FIGURE 5. Epanerchodus jiangxiensis n. sp., male paratype. A: anterior part of body, ventral view. B: anterior part of body, dorsal view. C. habitus, lateral view. D. midbody rings, dorsal view. E: posterior part of body, dorsal view. F: posterior part of body, ventral view. Scale bar: A, B, D–F, 0.2 mm; C, 0.5 mm.

FIGURE 6. Epanerchodus jiangxiensis n. sp., male paratype. A: gonopods, dorsal view. B: gonopods, ventral view. Photos no scale.

FIGURE 7. Epanerchodus jiangxiensis n. sp., male paratype. A: right gonopod, lateral view. B: right gonopod, mesal view. Abbreviations: en = endomere; ex = exomere; g = goove/gutter; k = femoral lobe; p = process; sg = seminal groove.