Orthomorpha laminata, Chen & Zheng & Jiang, 2023

Chen, Hui-Ming, Zheng, Chang-Bin & Jiang, Xuan-Kong, 2023, The millipedes (Diplopoda) in Yintiaoling National Natural Reserve, Southwest China, Zootaxa 5257 (1), pp. 49-81 : 63-65

Orthomorpha laminata sp. nov.

Figs 18–20

Type materials. Holotype male: China, Chongqing, Wuxi County, Tongcheng Town, Zengjiayan Cave , 31°22’30.23” N, 109°46’11.59” E, alt. 1301 m, 15 August 2022, X.K. Jiang & H.M. Chen leg. Paratypes: 3 males, same data as holotype ; 2 males and 2 females, Yintiaoling National Nature Reserve , Hongqi, Longtan Cave, 31°30’40.73” N, 109°49’40.93” E, alt. 1677 m, 14 August 2022, X.K. Jiang & H.M. Chen leg.

Diagnosis. This species can be distinguished from other species in this genus by the femorite of the gonopods extremely bent, lamellar processes present apically, and without an oblique lateral sulcus ( Figs 19 , 20 ).

Etymology. This species is named by the lamellar processes of the tip of femorite of the gonopods, adjective.

Description. Length ca. 43–50 mm (male), 45–48 mm (female), width of midbody pro- and metazona 3.7–3.8 and 5.2–5.3 mm (male), 3.9–4.7 and 5.2–6.0 mm (female), respectively. Head and dorsum of the body black, paraterga light yellow, venter and legs reddish brown ( Fig. 18A ).

Clypeolabral region sparsely setose, vertex bare, epicranial suture distinct. Antennae slender, antennomeres 2–7 clavate. Lengths of antennomeres: 3≈2≈4≈5≈6>1>7. Collum glabrous ( Fig. 18A ). Paraterga only slightly declivous, broadly rounded, and narrowly bordered. Postcollum constriction obvious. Tegument of metaterga shining, rugulose, prozona and metazona below paraterga smooth. Axial line barely visible both on pro- and metazona. Paraterga strongly developed, broad, subhorizontal, always lying below dorsum, thick in lateral view ( Fig. 18A, B ). Ozopores evident, lateral, lying in an ovoid groove at about 1/ 3 in front of caudal corner. Pore formula normal. Transverse sulcus evident, narrow, rather shallow and only slightly incomplete on metaterga 2 and 3, reaching base of paraterga on metaterga 4–18. Stricture between pro- and metazona narrow and shallow, evidently beaded at bottom down to base of paraterga. Sterna sparsely setose, without modifications, but with a small, rounded cone between male coxae 4. No conspicuous ridge in front of gonopod aperture. Legs long and slender, obviously longer than body height. Prefemora without modifications. Epiproct conical, flattened dorsoventrally, apical papillae well-developed ( Fig. 18C ). Hypoproct arch shaped.

Gonopods ( Figs 19 , 20 ) simple. Coxa long and slender, with several setae distodorsally ( Figs 19 , 20 ). Prefemora densely setose, about 1/3 as long as acropodite ( Figs 19 , 20 ). Femorite slender, evidently curved and not enlarged distad, without a lateral sulcus ( Figs 19 , 20 ). Tip of femorite present two lamellar processes ( Figs 19B , 20B ). One situated at the inner margin, with a sharp tip. Another one situated at the base of solenophore. Solenophore bent as semicircle. Tip of solenophore slightly bifid, upper denticle slender and longer than lower lobule. Lower lobule broad ( Figs 19B , 20B ). Solenomere about as long as solenophore, flagelliform ( Figs 19A, B ; 20A, B ).

Distribution. Known only from the type locality.

Remarks. Orthomorpha is distributed in southeast Asia and it is very similar to the sympatric genus Antheromorpha ( Likhitrakarn et al. 2011, 2016). Their taxonomic boundary is vague. Orthomorpha can only be distinguished from the latter by the poorly differentiated gonopod tip, usually feebly bi- or trifid, whereas Antheromorpha shows a deeply bifid gonopod tip ( Likhitrakarn et al. 2011, 2016). Considering the structure of the gonopod tip of the new species, we chose to place it in Orthomorpha .

Orthomorpha is a large genus comprising 50 species, and has been reviewed recently ( Likhitrakarn et al. 2011; Nguyen & Sierwald 2013). However, no species of this genus have been reported from China. Therefore, the new species described here is the first Orthomorpha recorded in this country.

Two individuals from deep inside Zengjiayan Cave show the distinct pale coloration of the body ( Fig. 18B ), but their gonopods are identical to the epigean congeners indicating that they belong to the same species.

Figures

FIGURE 18. Habitus of Orthomorpha laminata sp. nov. A. Anterior part of body, dorsal view; B. Midbody segments, dorsal view; C. Posterior part of body, dorsal view; D. Live specimen with pale coloration from Zengjiayan Cave. Scale bars: A, B = 2.5 mm; C = 1 mm.

FIGURE 19. Left gonopod of Orthomorpha laminata sp. nov., holotype. A. Mesal view; B. Ventral view; C. Lateral view. Scale bars: A–C = 0.5 mm.

FIGURE 20. Left gonopod of Orthomorpha laminata sp. nov., holotype. A. Mesal view; B. Ventral view; C. Lateral view. Scale bars: A–C = 0.5 mm. Abbreviations: c, coxa; pf, prefemur; sl, solenomere; sph, solenophore.