3.3. 3. Skleroprotopus megistus sp. nov.

Figures 2 B, 6

Material examined.

Holotype male (SCAU), China, Shaanxi Province, Xi’an City, Wangchuan County, Cave Lingyun Dong, 34°4′21.3′′N 109°23′45.01′′E, 900 m, 14. IX. 2017, Tian Mingyi, Huang Sunbin, Wang Dianmei and Yin Haomin leg. Paratypes: 6 males, 2 females (SCAU), same data as for holotype .

Diagnosis.

Differs from congeners mostly based on the following combination of characters: (1) telopoditomere 3 of male leg 1 particularly broad and bulging in the middle (Fig. 6 E); (2) penis subequal in height to coxae 2 (Fig. 6 F); (3) coxal process of male leg 7 very small, lower than the telopodite (Fig. 6 D); (4) anterior gonopod with a long coxal process carrying a highly developed, axe-shaped, membranous lobe (Fig. 6 I). — In addition, this new species differs from all other species analyzed in a> 10.3 % uncorrected p - distance of the COI barcoding gene.

Etymology.

Latinised Greek “ megistus ” is meaning “ large ”. The specific epithet refers to the male leg-pair 1 being particularly large; adjective.

Description.

Length of both sexes ca 31.5–40.0 mm, 1.8–2.2 mm in diameter, body with 53–65 podous + 1 apodous rings + telson. Natural coloration generally pale reddish brown (Fig. 2 B), in alcohol marbled yellowish brown. Antennae and legs light yellowish. Eye patches blackish, triangular, arranged in 4–6 irregular rows, altogether about 22–52 ommatidia per eye patch.

Head capsule smooth and hairless, eyes slightly bulged, epicranial suture well-defined. Labral margin with 4 + 4 supra-labral and 12 + 12 labral setae. Antennae very long and slender, reaching behind to middle of ring 5 when stretched dorsally. In length, antennomeres 3> 2> 4 ≈ 5> 6> 1> 7. Antennomeres 5, 6 and 7 each with a distal corolla of sensilla basiconica. Mandibular stipes well-rounded in males, more rounded in females. Gnathochilarium with at least 5 setae on each lamella lingualis (ll); promentum (pr) lance-shaped at base, swollen anteriorly, olive-shaped in males (Fig. 6 A), vs a narrow rhomboid pr in females (Fig. 6 B).

Collum with marbled brownish spots and 8–10 lower striae laterally, but lowest 3 striae not reaching the anterior margin. Prozona with 3–4 subtransverse striae and metazona with 13–22 longitudinal striae laterally. Suture dividing pro- and metazona very narrow, a regular comb. Ozopores starting with ring 6, lying mid-laterally on sides of metatergites (Fig. 2 B).

Epiproct slightly protruding caudad, posterior margin with 3 + 3 setae. Paraprocts convex, medially with 1 + 1 setae. Hypoproct eye-shaped, with 1 + 1 setae.

Legs medium-sized, about as long as midbody height. Male leg-pair 1 (Fig. 6 E) hypertrophied, 5 - segmented, tip slightly curved anteriad. Coxa (cx) and telopoditomeres 1 and 2 (t 1, t 2) with some long setae. Telopoditomere 3 (t 3) widest and largest, bulging in the middle. Telopoditomere 4 (t 4) subtriangular; t 3 and t 4 devoid of long setae. Male leg-pair 2 (Fig. 6 F) reduced in size; penis (pn) subequal in height to coxae (cx), distal part with three long setae. Male leg-pair 7 (Fig. 6 D) reduced, with 2 - segmented telopodites (te), t 1 large and setose subapically; coxal process (cp) very small, lower than telopodite (te), with several long setae distally.

Anterior gonopods (Fig. 6 H, I) with a very long coxal process (cp) bearing an oval field of short villi in anterior view, posteriorly carrying with a highly developed, axe-shaped, membranous lobe (ml), slightly lower than cp, outer margin of ml with a large, sharp and triangular protrusion, clearly wider than cp. Flagellum (f) very long and slender, villose in distal part. Telopodite (te) about half as long as cp, with long setae apically, laterobasally with a minute remnant (r) of a second podomere.

Posterior gonopods (Fig. 6 G, J) stout, anterior branch slender and with a small pointed tip, posterior one semi-annulate and densely setose distally.

Vulva (Fig. 6 C) as usual, with two parallel rows of short setae on anterior and posterior surfaces, and two long distal setae on operculum (op).

Remarks.

Lingyun Dong is a karst cave open to the public in the Wangchuan Scenic Area, which is about 500 meters long. Based on the unpigmented body and long antennae, S. megistus sp. nov. is considered a troglobite.