Skleroprotopus longissimus, Chen & Zhao & Golovatch & Liu, 2024

Chen, Rong, Zhao, Yi, Golovatch, Sergei & Liu, Wei-Xin, 2024, Molecular phylogenetic and morphological studies reveal increased species diversity in the millipede genus Skleroprotopus Attems, 1901 in China (Julida: Mongoliulidae), Arthropod Systematics & Phylogeny 82, pp. 659-691 : 659-691

3.3. 7. Skleroprotopus longissimus sp. nov.

Figures 2 C , 10

Material examined.

Holotype male ( SCAU), China, Hunan Province, Chenzhou City, Guidong County, Sidu Town , Cave Bidongfeiyan Dong , 26°0′13.32′′N 113°46′28.25′′E, 800 m, 19. X. 2013, Tian Mingyi, Liu Weixin and Yin Haomin leg. Paratypes: 1 male, 5 females, 4 juveniles ( SCAU), same data as for holotype ; 7 males, 13 females, 1 juvenile, same cave, 4. IV. 2021, Tian Mingyi and Cheng Jingli leg. Other material examined: 4 males, 5 females, 2 juveniles ( SCAU), same county, Sidu Town, Cave Sidu Dong , 25°57′46.55′′N 113°47′07.33′′E, 900 m, VII. 2011, Tian Mingyi, Gao Qi and Sun Feifei leg.

Diagnosis.

Differs from congeners mostly based on the following combination of characters: (1) penis much shorter than coxae 2 (Fig. 10 E ); (2) male leg-pair 7 with a rather long and slender coxal process (Fig. 10 F ); (3) anterior gonopod (Fig. 10 G, H ) with a very long coxal process carrying an irregularly dentate and membranous lobe, and a very long and slender flagellum. — In addition, this new species differs from all other species analyzed in a> 12.4 % uncorrected p - distance of the COI barcoding gene.

Etymology.

Latin “ longissimus ” is meaning “ the longest ”. The specific epithet refers to the coxal process of male leg-pair 7 being particularly long and relatively slender; ajective.

Description.

Length of both sexes ca 25.0–40.0 mm, 1.6–1.9 mm in diameter, body with 47–54 podous + 1 apodous rings + telson. Natural coloration (Fig. 2 C ) red brownish, in alcohol uniformly brown yellowish, prozona dark brownish, metazona yellowish. Antennae and legs light yellowish. Eye patches blackish, subtriangular, arranged in 4–7 irregular rows, altogether about 20–37 ommatidia per eye patch.

Head capsule smooth and hairless, eyes slightly bulged, epicranial suture well-defined. Labral margin with 2 (3) + 2 (3) supra-labral and 9 + 9 labral setae. Antennae of medium length, reaching behind to anterior of ring 3 when stretched dorsally. In length, antennomeres 3> 2> 4 ≈ 5> 6> 1> 7. Antennomeres 5 and 6 each with a distal corolla of sensilla basiconica. Mandibular stipes well-rounded, with two small lobes in males, more rounded in females. Gnathochilarium with at least 4 setae on each lamella lingualis (ll); promentum (pr) relatively narrow, lance-shaped at base, swollen anteriorly and cup-shaped in males (Fig. 10 A ), vs a slightly broadened and oblong rhomboid pr in females (Fig. 10 B ).

Collum with 5–7 lower striae laterally, but lowest 2 striae not reaching the anterior margin. Prozona with 4–6 irregular subtransverse striae and metazona with 11–25 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.

Epiproct slightly protruding caudad, with 4 + 4 setae at posterior margin. Paraprocts convex, with 2 + 2 setae. Hypoproct eye-shaped, with 1 + 1 setae.

Legs long and slender, about 1.1 × as long as midbody height. Male leg-pair 1 (Fig. 10 D ) hypertrophied, 5 - segmented, strongly curved anteriad; coxa (cx) and telopoditomeres 1 and 2 (t 1, t 2) with some long setae. Telopoditomere 3 (t 3) longest, about as long as all other telopoditomeres combined; Telopoditomere 4 (t 4) irregularly shaped, with two vague emarginations, one lateral, the other dorsal. Male leg-pair 2 (Fig. 10 E ) reduced in size and very slender; penis (pn) shorter than coxae (cx), distal part with three long setae. Male leg-pair 7 (Fig. 10 F ) strongly modified, coxal process (cp) extremely long and slender, crowned with a small hook facing anteriorly, strongly bent frontally, mostly subparallel-sided, considerably more slender, and free from setae along distal 2 / 3; telopodite (te) 1 - segmented, rather small, carrying a long apical seta.

Anterior gonopods (Fig. 10 G, H ) with a medium length coxal process (cp), posteriorly carrying with an irregularly dentate membranous lobe (ml), outer margin of ml somewhat broadened and reflexed in proximal half, margin of reflexed part irregular. Flagellum (f) very long and slender, distally serrate and branched. Telopodite (te) about 3 / 4 as long as cp, with long setae both apically and mesally, laterobasally with a minute remnant (r) of a second podomere.

Posterior gonopods (Fig. 10 I ) erect, branched at tip, anterior branch smooth, with a pointed tip, posterior one densely setose.

Vulva (Fig. 10 C ) as usual, with two parallel rows of short setae on both anterior and posterior surfaces, operculum (op) with several long setae distally.

Remarks.

Sidu Karst is located in the Bamianshan National Nature Reserve, being the largest cave group found so far in southern Hunan. As the antennae and legs of this species are apparently slender and unpigmented, albeit the body retains some pigment, S. longissimus sp. nov. is considered a troglobite.

Figures

Figure 2. Pictures of live animals, photos by Prof. Mingyi Tian from SCAU. A Skleroprotopus change sp. nov.; B Skleroprotopus megistus sp. nov.; C Skleroprotopus longissimus sp. nov.; D Skleroprotopus genjudi sp. nov.; E Skleroprotopus tiankeng sp. nov.; F Skleroprotopus laiyuanensis sp. nov.; G Skleroprotopus incisodentatus sp. nov.

Figure 10. Skleroprotopus longissimus sp. nov. . paratypes from Cave Bidongfeiyan Dong. A, D – I male paratype; B, C female paratype. A, B gnathochilarium; C right vulva, mesal view; D legs 1, anterior view; E legs 2 with penis, posterior view; F legs 7, anterior view; G anterior gonopods, anterior view; H anterior gonopods, posterior view; I posterior gonopods, anterior view. Abbreviations: cp, coxal process; cx, coxa; f, flagellum; ll, lamella lingualis; ml, membranous lobe; op, operculum; pn, penis; pr, promentum; r, remnant; t 1 – t 4, telopoditomeres 1–4; te, telopodite. Scale bars: 0.2 mm.