Stemmiulus uncus Nzoko Fiemapong & VandenSpiegel

Fiemapong, Armand Richard Nzoko, Masse, Paul Serge Mbenoun, Tamesse, Joseph Lebel, Golovatch, Sergei Ilyich & VandenSpiegel, Didier, 2017, The millipede genus Stemmiulus Gervais, 1844 in Cameroon, with descriptions of three new species (Diplopoda, Stemmiulida, Stemmiulidae), ZooKeys 708, pp. 11-23 : 14-17

Stemmiulus uncus Nzoko Fiemapong & VandenSpiegel sp. n. Figure 2

Type material.

Holotype ♂ (MRAC 22727), Cameroon, South Region, Vallée du Ntem Division, Engout’Adjap, N02°42', E011°09', ca 2010 m a.s.l., slightly disturbed natural forest under dead leaves, forest, 13.IX.2014, leg. A. R. Nzoko Fiemapong.

Paratypes: 1 ♂ (MRAC 22728), same data, together with holotype; 1 ♂ (SEM, MRAC 22729), same locality, but 14.III.2015, all leg. A. R. Nzoko Fiemapong.

Etymology.

The species name emphasizes the characteristic apical part of the colpocoxite which is unciform and pointed at the apex.

Diagnosis.

A species of Stemmiulus characterized by the first six ambulatory legs being especially robust and covered with peculiar, spatulate setae, also showing a field of numerous simple setae on the inner side of the tarsus (Fig. 2 B–E). The gonopod has a relatively simple angiocoxite which forms a densely setose apical corolla. The tip of the colpocoxite forms a characteristic apical hook.

Description.

Holotype: adult male, ca 20 mm in length, 1.8 mm in maximum diameter, body with 46 rings. Head and collum dark brown, other body rings brown with a light axial dorsal stripe, legs and antennae yellowish.

Head typical in shape, beset with numerous simple macrosetae; ommatidia 2+2, posterior ommatidia larger than anterior ones; antennae long and setose, apices reaching third body ring. Gnathochilarium concave, stipes densely and uniformly porose, pores surrounded by a field of minute setae.

Collum with a single fold at anterior edge, this being better expressed at lateral margin.

Body rings ovoid (height/width ratio of midbody rings ca 0.31), telson short and upcurved. Both pro- and metazonites with transverse oblique striae better pronounced at pleurotergal margin.

First six pairs of legs as in S. ongot sp. n., but mostly with filiform and plumose setae (Fig. 2B-E). First pair of legs relatively simple and unmodified.

Second pair of legs with enlarged coxae (Fig. 2F, G), their anterior surface with a few setae, posterior surface glabrous. Telopodite 2-segmented, proximal segment longer, about twice as long as distal segment, curved caudad, with a ventromedial cluster of long setae (Fig. 3G). Distal segment more slender, with an apical row of short setae (Fig. 3G).

Gonopods (Fig. 2H, I) with a large and relatively simple angiocoxite forming an apical corolla and covered with a dense field of numerous setae. Colpocoxite with its tip forming a characteristically strong and curved hook (Fig. 2 H–J).

Paragonopods small and 3-segmented, each of medial and distal segments carrying a small series of short setae.

Female unknown.

Relationships.

The peripheral characteristics and simple gonopods bring S. uncus sp. n. close to S. beroni , from Nigeria, and S. pullulus , from Mount Nimba. All these species share the simplicity of their second pairs of male legs, despite the fact that the basal segment of the telopodite in the new species is about twice as large and broad as the distal segment. Nevertheless, the males of this trio can easily be distinguished by the structure of the apical part of the colpocoxite. The latter ends up in a pointed curved hook in S. uncus , versus a pointed straight tip in S. beroni or a rounded tip in S. pullulus .

Distribution.

Known only from the type locality.