Siliquobolellus constrictus gen. et, 2022

Pimvichai, Piyatida, Enghoff, Henrik, Panha, Somsak & Backeljau, Thierry, 2022, A new genus of Pseudospirobolellidae (Diplopoda, Spirobolida) from limestone karst areas in Thailand, with descriptions of three new species, Zoosystematics and Evolution 98 (2), pp. 313-326 : 313

Siliquobolellus constrictus gen. et sp. nov.

Figs 2 , 4 , 6 , 7

Material studied.

Holotype. 1 male (CUMZ-D00150-1), Thailand, Prachuap Khiri Khan Province, Kui Buri District, Ban Yang Chum ; 12°04'19.64"N, 99°42'57.63"E; 149 m a.s.l.; 7 August 2014; C. Sutcharit leg.

Paratypes. 1 male (CUMZ-D00150-2), 2 females (CUMZ-D00150-3); same data as holotype .

Etymology.

The species epithet is a Latin adjective derived from the verb constringere = "to tighten" and refers to the constricted anterior gonopod coxa.

Diagnosis.

Differing from other species in the genus by having the anterior gonopod coxae constricted at middle of lateral margin, while the other two species have no constriction at middle of lateral margin of anterior gonopod coxae; externally differing by having a middorsal row of triangular dark brown spots, with dark brown bands on both lateral sides running parallel to the dorsal one.

Description.

Adult males with 41 or 42 podous rings, 1 apodous ring. Length ~3 cm, diameter 3.6-3.7 mm. Adult females with 42 or 43 podous rings, 1 apodous ring. Length ~3 cm, diameter 4.1-4.5 mm.

Colour. After 8 years in alcohol overall beige with 3 stripes from head to telson: a mid-dorsal row of triangular dark brown spots, with dark brown bands on both lateral side running parallel to the dorsal one (Fig. 2J ).

Anterior gonopods (Fig. 4A, B, D, E ) with a small triangular process between coxae (st), with high coxae, broad at base, gradually narrowing towards tip, distinctly constricted at middle of lateral margin, apical part flattened, curving mesad, mesal margin basally straight, curving towards tip, posterior surface folding cover more than half of telopodite. Telopodite small, directed distad, thumb-like process, with longitudinal ridge from base to tip (Fig. 4B , arrow).

Posterior gonopods (Fig. 4C, F-J ) simple, rounded, with short, smooth coxal part (pcx); telopodital part (pt) twice the length of the pcx, lateral margin expanded, folding mesad, forming a concavity (not so deep as in the other two species).

Female vulvae (Fig. 4K ): simple, valves prominent, the left valve slightly larger than the right valve.

DNA barcode.

The GenBank accession number of the COI barcode of the paratype is OP174622 (voucher code CUMZ-D00150).

Habitat.

Found under leaf litter.

Distribution.

Known only from the type locality in Prachuap Khiri Khan Province, Thailand (Fig. 7 ).

Figures

Figure 2. External morphology of Siliquobolellus gen. nov. A - C. S. amicusdraconis gen. et sp. nov. A. Head, lateral view; B. Head, ventral view; C. Posterior end, lateral view; D. Posterior end, lateral view (S. prasankokae gen. et sp. nov.); E. Posterior end, lateral view (S. constrictus gen. et sp. nov.); F-I. S. prasankokae gen. et sp. nov.; F. Posterior end, ventral view; G, H. Male leg, latero-ventral view; I. Body rings, dorsal colour pattern; J. S. constrictus gen. et sp. nov., body rings, dorsal colour pattern. Av = anal valves; Gst = gnathochilarial stipes; IL = incisura lateralis Me = mentum; Mst = Mandibular stipes; Pre = preanal ring; Sub = subanal scale.

Figure 4. Siliquobolellus constrictus gen. et sp. nov., holotype, gonopods (specimen from Ban Yang Chum, CUMZ-D 00150 - 1). A. Anterior gonopod, anterior view; B. Anterior gonopod, posterior view, arrow indicates a thumb-like process, with longitudinal ridge; C. Right posterior gonopod, lateral view; D. Anterior gonopod, anterior view; E. Anterior gonopod, posterior view; F. Right posterior gonopod, lateral view; G. SEM, Left posterior gonopod, lateral view; H. SEM, Left posterior gonopod, latero-mesal view; I. SEM, tip of left posterior gonopod, latero-mesal view; J. SEM, Mesal part of left posterior gonopod, lateral view; K. SEM, left female vulva, posterior mesal view. at = anterior gonopod telopodite; cx = coxa; oeg = opening of efferent groove; op = operculum of vulva; pcx = coxal part of the posterior gonopod telopodite; pt = telopodital part of the posterior gonopod telopodite; st = sternal process.

Figure 6. Live Siliquobolellus gen. nov. species from Thailand. A, B. S. amicusdraconis gen. et sp. nov. (from Hub Pa Tard), female (paratype, CUMZ-D 00149 - 2); C, D. S. prasankokae gen. et sp. nov. (from Pha Thai), male (holotype, CUMZ-D 00148 - 1).

Figure 7. Geographic location of the type localities of Siliquobolellus gen. nov. species.