Ostinobolus subterraneus Wesener, 2009

Wesener, Thomas, Enghoff, Henrik & Sierwald, Petra, 2009, Review of the Spirobolida on Madagascar, with descriptions of twelve new genera, including three genera of ' fire millipedes' (Diplopoda), ZooKeys 19 (19), pp. 1-128 : 95

Ostinobolus subterraneus Wesener , sp. n.

urn:lsid:zoobank.org:act:F5D60255-4786-4DB3-BA0E-DC3A49AF18EA

Material examined: 2 ♂, 10 ♀, 21 imm. Holotype: 1 ♂ (30 mm long), FMMC 8215 , Province Toliara, Petriky , 10 m, littoral subhumid forest on sandy soil; 25°3.73’ S, 46°52.16’ E, leg. B. L. Fisher, Winkler extraction, 22.IX.1998.

Other material examined: 1 ♂, 5 ♀, 8 imm., FMMC W010 B, Ambatotsirongorongo Mountain, Forêt Petit Lavasoa , rainforest, 25°05.021’ S, 46°46.110’ E, leg. T. Wesener et al., 21.V.2007 ; 1 ♀, ZMH W010 B, same data as previous ; 4 ♀, 8 imm., W010B, same data as previous, voucher specimens deposited at the University Antananarivo ; 3 imm., FMMC W099 , Ambatotsirongorongo Mountain, Grand Lavasoa , rainforest, 25°5’10.23” S, 46°44’55.93” E, leg. Wesener et al., 14.VI.2007 .

Differential diagnosis: until now, no other species of Spirobolida with a reduced number of ocelli is known from Madagascar. Because of the unusual morphological adaptation to the special life style, the placement of O. subterraneus inside Ostinobolus is only tentative and less certain than in other Spirobolida species.

Description. Measurements: males with 42–44 body rings, circa 30 mm long (broken), 2.7–3.2 mm wide. Females of similar length and width.

Coloration faded in alcohol. Head, legs anal valves, median part of collum and posterior part of metazonites brownish-red. Mesozonites and anterior part of metazonites dark grey ( Figs 52 A–C). Eyes reduced, with circa eight decolorized ocelli ( Fig. 52A ). Antennae protruding back to ring 3 ( Fig. 52A ). First leg pair elongated, larger than second pair ( Fig. 52A ). Legs very short, length only 0.4 times body diameter ( Fig. 52B ). Male coxal processes absent ( Fig. 52B ). Preanal process absent, but anal valves not elongated posteriorly like in congeneric species ( Fig. 52C ).

Anterior gonopod sternite wide. Lobe short, triangular with a sharp tip ( Fig. 52E ). Sternite tip protruding as high as coxite. Telopodite large, with a well-developed and well-rounded retrorse process, starting at midpoint of telopodite, retrorse part extending beyond telopodite but not coxite ( Fig. 52G ).

Posterior gonopods: short and wide ( Fig. 52F ). Apical half of mesal margin filled by a swollen, membranous area. No trace of star-shaped membranous folds. Sperm canal protruding above telopodite margin mesally into a two-tipped lobe ( Fig. 52H ).

Distribution and ecology: only known from a small area in the extreme southeast of Madagascar. The species is obviously microendemic to the subhumid forest of Petriky and five kilometers south of the isolated rainforest sites on the Ambatotsirongorongo Mountain ( Fig. 49 ). Unlike cave dwelling millipede species, Ostinobolus subterraneus sp. n. does not display elongated legs and antennae. The reduced number of ocelli and the elongation of the first leg pair are probably an adaptation to life inside the thick root horizon, the only place where this species was collected.

Etymology: subterraneus , adjective, refers to the life deep inside the soil to which this species is adapted.

Figures

Figure 49. Distribution map of the genus Ostinobolus gen. n..

Figure 52. Ostinobolus subterraneus sp. n., male holotype. A head, lateral view B legs 1–7, ventral view C telson D gnathochilarium, ventral view E anterior gonopod, anterior view F right posterior gonopod, anterior view G anterior gonopod, posterior view H right posterior gonopod, posterior view. av = anal valves; Co = collum; Cx = coxite; E = reduced eye; Gn = gnathochilarium; L = ledge; Md = mandible; Pre = preanal ring; St = sternite; T = telopodite. Scale bars = 1 mm.