Obelostreptus bilamellatus VandenSpiegel, 2015

Mwabvu, T. & VandenSpiegel, D., 2015, A review of the genus Obelostreptus Attems, 1909 (Diplopoda, Spirostreptida, Spirostreptidae) with the description of a new species from Kenya, African Invertebrates 56 (1), pp. 51-51 : 54-56

Obelostreptus bilamellatus VandenSpiegel , sp. n.

Fig. 3A–G

Etymology: Referring to the two lamellate processes occurring on the distal half of the telopodite.

Diagnosis: Lateral margins of coxites convex, tapering and hook-shaped apically ( Fig. 3B, E ). Distal half (post-knee) of telopodite with two adjacent and different sized lamellated processes ( Fig. 3B, D ).

Description (holotype):

Adult male with 46 body rings, length ± 50 mm, maximum diameter c. 3 mm.

Body colour dominantly brownish, prozonite yellowish brown, metazonite dark brown. Head surface smooth, c. 30 ocelli disposed in five rows (4, 5, 7, 9, 5), length of antenna approximately half of the body diameter, four sensory cones on last article. Pre-mandible rounded ventrally with no projection. Collum rounded laterally, surface virtually smooth and polished.

Body rings with low longitudinal ridges on metazonite, metazonite slightly greater in diameter than the prozonite, with a distinct suture, ozopores rather discreet but distinct.

Paraprocts convex, distal margins set off by submarginal groove. Hypoproct not fused with preceding segment.

First pair of legs of males with prominent prefemoral processes ( Fig. 3A ). Walking legs elongated (length greater than body diameter) with large ventral tibial pads extending up to the proximal half of the tarsus.

Gonopods with a small, medially divided sternum, distal parts with an extending lateral cone projecting outside the body when at rest. Gonocoxa oblong, with a hook-shaped distal part, a small anterolateral metaplical process and a well-developed median metaplica lobe ( Fig. 3B, E ). Form of the telopodite highly characteristic as shown in Fig. 3B, C and F . Just after its emergence from the gonoschima, the telopodite gives rise to an elongated antetorsal process and, beyond this, are two different sized post-knee lamella-shaped processes ( Fig. 3B, C, F ).

The male paratypes agree precisely with the holotype in coloration and structural detail; they are nearly the same size and also have 46 segments.

The females are longer and wider than males; first pair of legs not modified; vulva poorly sclerotized, valves equal in size, smooth without setae ( Fig. 3G ).

Holotype ♂: KENYA: Taita Hills, Ngangao Forest (03°22'S 38°21'E), 1820 m, 19.vi.1999, D. VandenSpiegel ( MRAC 22541 ).

Paratypes: 2♂ 2♀ same data as holotype ( MRAC 22540 ) ; 2♂ 2♀ same data as holotype ( MRAC 22542 ) ; 1♂ 1♀ same data as holotype ( ZMUC) ; 1♂ 1♀, same data as holotype ( MNHN) ; 1♂ 1♀ same data as holotype ( MRAC 22539 ) ; 2♂ same data as holotype ( MRAC 22543 ) .

Other material examined: KENYA: 2♂ 1♀: Taita Hills, Mbololo forest (03°19'S 38°27'E), 1800–1900 m, 21.vi.1999, D. VandenSpiegel ( MRAC 17.972 ) ; 2♂ 2♀ Taita Hills, Mbololo forest (03°19'S 38°27'E), 1800–1900 m, 22.vi.1999, D. VandenSpiegel ( MRAC 17.986 ) ; 100 specimens Taita Hills, Ngangao Forest (03°22'S 38°21'E), 1820 m, 19.vi.1999, D. VandenSpiegel ( MRAC 18.005 ) ; 1♂ 3♀ Taita Hills, Mbololo forest (03°19'S 38°27'E), 8.xii.1999, D. VandenSpiegel & J. P. Michiels ( MRAC 18.411 ) ; 1♂ 2♀ Taita Hills, Chawia forest (03°29'S 38°20'E), 7.xii.1999, D. VandenSpiegel & J. P. Michiels ( MRAC 18.428 ) ; 1♂ 3♀ Taita Hills, Fururu forest (03°26'S 38°20'E), 9.xii.1999, D. VandenSpiegel & J. P. Michiels ( MRAC 18.448 ) ; 20 specimens Taita Hills, Ngangao Forest (03°22'S 38°21'E), 4.xii.1999, D. VandenSpiegel & J. P. Michiels ( MRAC 18.477 ) ; 54 specimens Taita Hills, Ngangao Forest (03°22'S 38°21'E), 1820 m, 19.vi.1999, D. VandenSpiegel ( MRAC 22538 ) .

Distribution: Only known from Taita Hills, Kenya.

Remarks: The coxites of the gonopods resemble those of O. acifer by being convex laterally and tapering apically. However, unlike in O. bilamellatus the coxites in O. acifer are not hooked apically. The telopodite is typical of the genus, having a characteristic antetorsal process just before the major curvature of the telopodite.

Figures

Fig. 3. Obelostreptus bilamellatus: (A) first pair of legs of male, anterior view; (B) posterior aspect of gonopods;(C)left telopodite,sublateral aspect;(D)apical part of telopodite;(E)drawing of gonopods, posterior view; (F) drawing of telopodite; (G) right vulva, posterio-lateral view.Scale bars = 100µm. Abbreviations: alp – anterolateral process, ant – antetorsal process, dcx – distal part of coxite, lb – lobe, lmp – lamellate processes, lov – lobe of oral valve, me – metaplica, mml – median metaplica lobe, op – opercule, slm – solenomerite, tp – telopodite.