Ammodesmus nimba, VandenSpiegel, Didier & Golovatch, Sergei, 2012

VandenSpiegel, Didier & Golovatch, Sergei, 2012, The millipede family Ammodesmidae (Diplopoda, Polydesmida) in western Africa, ZooKeys 221, pp. 1-17 : 9-11

Ammodesmus nimba sp. n. Figs 28-46

Type material.

Holotype ♂ (MRAC 22510), GUINEA, Mt Nimba, Freton forest, 07°37'N, 008°29'W, soil and litter, Winkler extraction, 10.III.2012, leg. A. Henrard, C. Allard, P. Bimou & M. Sidibé. Paratypes: 12 ex. (MRAC 22511), 1 ♂, 1 ♀ (ZMUM), 1 ♂ (MNHN), same locality, together with holotype.

Diagnosis.

Minute polydesmidans with a characteristic, spotty colour pattern of the caudal edge of each segment. Gonopods with extremely large coxae concealing the telopodites inside a deep gonocoel.

Description.

♂ca 2.8 mm long; maximum width, 0.9 mm. Body integument light brown to pinkish. Colour pattern of metaterga characteristic, spotty (Fig. 28). Body with 19 body rings (17+1+T), shape as in Figs 28, 29.

Head small, partly concealed under front edge of collum; upper half of head densely granular, lower half smooth and densely setose. Interantennal isthmus without knob, about as wide as antennomere 1 (Fig. 34). Antennae as in Fig. 34. Collum relatively large, rather convex, surface slightly granular. Tergum 2 as usual, hypertrophied, with strongly enlarged, spatuliform paraterga concealing the head in lateral view (Figs 28, 29, 30), ventral edge with up to 4 rows of granules (Figs 29, 30). Limbus smooth, 2nd and following metaterga with a row of up to 13 low bosses lining the caudal margin; each boss obviously supporting a small apical seta (Figs 30-33, 38). Prozona rugose anteriorly, with a row of small granules along anterior edge of metatergum (Fig. 39). Paraterga set below segments’ midheight, continuing the convex outline of dorsum, with a notch basally at posterolateral edge; ends rather regularly rounded, increasingly angular towards telson (Figs 31, 32, 36). Anteroventral parts of paraterga 3 to 15 with a notch forming a groove for paraterga 2 to hinge into during volvation (Fig. 37). Ozopore formula: 5, 7, 9, 10, 12, 13, 15, 17; ozopores opening flush on tergal surface at about anterior third of paraterga, openings oblong and not concealed by preceding paraterga (Fig. 36). Telson small (Figs 32, 36).

Sterna and legs as in Ammodesmus granum (Figs 40, 41, 42). Gonopod aperture relatively modest in size, transversely oval (Fig. 43).

Gonopods highly complex (Figs 43-45); coxae oblong, strongly enlarged to protect telopodites (Figs 43, 45). Telopodite only a little longer than coxa, showing a hook-shaped apical part (Figs 44, 45b) carrying a digitiform tubercle (Figs 43, 44, 45c). Solenomere very small and short, supplied with a distinct hairy pulvillus (Fig. 45a).

♀ agrees precisely in colour and structural details with ♂, also being (nearly) of the same size and counting 19 body rings. Vulva small, setose, poorly sclerotized, edge of bursa with some particularly long setae (Fig. 46).

Relationships.

Superficially, both species of Ammodesmus might look sufficiently different to consider them as representing different genera, especially as regards the absence of sexual dimorphism in metatergal structure and the presence of a deep gonocoel in Ammodesmus nimba as opposed to Ammodesmus granum . The main distinctions can also be summarized in a tabular form (Table). However, based on all evidence, we are rath er inclined to recognize only two valid genera in Ammodesmidae , both quite disjunct also geographically (Fig. 47).

Name.

Referring to the type locality, a noun in apposition.

Distribution.

Known only from the type locality and probably endemic to Mt Nimba.