Epanerchodus gladiatus, 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 : 67-70

Epanerchodus gladiatus , new species

Figs 12–13 .

Material examined: Holotype male ( SCAU eGZ13-1) from China, Guizhou Province, Wuchuan County, Huangdu Town, Gaodong Village , Yinshi Dong Cave , 29.VII.2015, colls: Mingyi Tian and Jingli Cheng . Paratypes: 1 male, 2 females ( SCAU eGZ13-1), same data as the holotype .

Diagnosis: Adult males of E. gladiatus n. sp. are distinct from other Epanerchodus species based on the following combination of characters: (1) body small (ca 15–17 mm long); (2) gonopod suberect and slender; (3) endomere sword-shaped, with a small, rounded, ventral bump (a) and a prominent, digitiform, mesal process (p) at base ( Fig. 13 ).

This new species is similar to E. chutou n. sp. (from a cave in Guizhou, China) in the endomere showing a basal outgrowth and a missing exomere. However, E. gladiatus n. sp. is distinguished by the endomere being sword-shaped, with a small, rounded, ventral bump (a) ( Fig. 13 ) vs. endomere hoe-shaped, with a slender, spiniform, basal process (a) in E. chutou n. sp. ( Fig. 15 ).

Description: Based on type specimens. Lengths of both sexes ca 15–17 mm, widths of pro- and metazonae 1.2– 1.3 mm and 2.5–3.0 mm. Coloration: in alcohol generally pallid. Mouthparts and gonopodal telopodites light yellowish. Body: Adults with 20 rings. Width: head << collum <ring 3 <4 <2 <5–15, thereafter body gradually tapering towards telson. Head: clypeus densely pilose, vertex sparsely setose, epicranial suture conspicuous ( Fig. 12B ). Antennae long, reaching behind posterior margin of ring 3 when extended posteriorly, slightly clavate ( Fig. 12 ). Exoskeleton: Collum fan-shaped, with a lateral incision on each side. Paraterga evident ( Fig. 12 ), midbody paraterga extend metatergite to ca 2.1x width of prozonite. Paraterga on collum and rings 2–7 clearly upturned dorsally above a faintly convex dorsum, other paraterga flat ( Fig. 12 ). Caudolateral corners of paraterga increasingly acute-angled, especially strongly projecting posteriorly past tergal margin on rings 17–19 ( Fig. 12A ). Integument shining, translucent, prozonae very delicately alveolate. Limbus regularly denticulate. Constriction between pro- and metazonae narrow, shallow and smooth. 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, present sometimes only on collum, ring 2 and ring 19.Three or four faint setigerous incisions at lateral margins of poreless and pore-bearing rings, respectively. 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 shallow. Legs long and slender, about 2.2–2.5 times as long as body ring height in both sexes, without sphaerotrichomes or sternal cones, prefemora not bulging laterally. Gonopods: slender ( Fig. 13 ). Telopodite linear, erect. Prefemur densely setose, about half as long as telopodite. Clivus (cl) a small bump. Endomere (en) slender, sword-shaped, broadened at midway and distally, but constricted between. Endomere apex subacuminate, with a small, rounded, ventral bump (a) and a prominent, digitiform, mesal process (p) at base. Seminal groove starting mesally, then recurving laterad to run into an accessory seminal chamber, the latter opening on a hairy pulvillus. An exomere absent.

Note: Due to the long and slender antennae and legs, and a depigmented cuticle, this species is most likely a troglobite.

Etymology: To emphasize the endomere being sword-shaped; masculine adjective.

Figures

FIGURE 12. Epanerchodus gladiatus n. sp., male paratype. A: habitus, dorsal view. B: habitus, ventral view. Scale bar: 0.2 mm.

FIGURE 13. Epanerchodus gladiatus n. sp., male paratype. A: left gonopod, mesal view. B: left gonopod, lateral view. Abbreviations: a = outgrowth; cl = clivus; en = endomere; p = process.

FIGURE 15. Epanerchodus chutou n. sp., male paratype. A: right gonopod, lateral view. B: right gonopod, mesal view. Abbreviations: a = spiniform process; cl = clivus; en = endomere; p = process.