Scolopendrelloides congolensis, Camacho, Miguel Domínguez, 2010

Camacho, Miguel Domínguez, 2010, New insights on the genus Scolopendrelloides Bagnall 1913 (Scutigerellidae, Symphyla) with descriptions of two new species, Zootaxa 2558, pp. 48-60 : 49-51

Scolopendrelloides congolensis n.sp.

Material examined. 15 specimens from the Democratic Republic of the Congo.

Type material. Holotype: RMCA 22133, adult female, 2.5 mm (without the antennae), Albert National Park, Secteur Sud, collected by R.P. Celis. Paratypes: RMCA 22134, 1 adult female, 2.5 mm and 1 juvenile male with 10 pairs of legs, 2 mm, same data as holotype; RMCA 22135, 1 adult, sex unknown, Albert N.P., Sect. Sud, collected by R.P. Celis; RMCA 22136, 1 adult female, 2.3 mm, Albert N.P., Secteur Ruwenzori, Kibombole riv., 22.VIII.1955, collected by P. Vanschuytbroeck; RMCA 22137, 2 adult females and 1 adult male, about 2 mm, Albert N.P., Sect. Sud, riv. Gahama, affluent Geramihasha, 28.VI.1954, collected by G.F. De Witte; RMCA 22138, 1 adult male (?), 3 mm, Katanga, mont Kabobo, Ht. Kiymbi, Tanganika ( Congo D.R), 1850 m; RMCA 22139, 3 adult males, about 2 mm, Kivu, terr. d’Uvira, Mulenge, 2200 m; RMCA 22140, 2 adult females and 1 adult male, 1.5–2.5 mm, Albert N.P., Sect. Sud, Katare, rég. Rutshuru, 1250 m, 22.09– 23.11.1954, collected by G.F. De Witte.

Length 1.5–3 mm.

Head 1.15 times as long as broad, somewhat heart-shaped and a bit flattened laterally ( Fig. 1 B, D). Central rod complete until the most posterior point of the head, where it forms a triangular area, but not visible in the median part of the head. Lateral branches present, a bit curved backwards and very slightly in the median part of the head. Frontal and posterior branches absent. Only the small exterior opening of the Tömösváry’s organ sometimes visible, when not hidden by a fold of the membrane. Dorsal surface of the head with thin, straight setae. Cuticle glabrous.

Antennae. They are broken in the holotype. Paratype from Kivu with 28 segments.

Tergites. First tergite small, subelliptical and about five times as wide as long, with 10–12 setae of which 3 or 4 are much longer than others—the lateral and both submedial ones. Following tergites large, somewhat elliptical with concave margins and small pointed tips at the end of emarginations ( Fig. 1 C). The form of the emargination and of the pointed tips vary among the specimens, the margin of the tergites varies from more angular to more rounded and the posterior tips from more protruding to more rounded ( Fig. 1 C, D). Second and third tergites with two lateral macrochaetae on each side, the anterior one a bit longer than the posterior. Following tergites with at least a pair of outwards directed macrochaetae. Cuticle of all tergites glabrous, with a slight mesh pattern. In the most anterior part of the tergites 3–15 this pattern forms lateral lines with rows of tiny backwards directed setae. Mesh pattern more conspicuous on the more posterior tergites, where it looks scaly. Penultimate tergite with a single pair of lateral macrochaetae and no visible setae on the margin of the concave emargination ( Fig. 1 I).

Cerci 3 times as long as wide ( Fig. 1 I). Margins nearly straight, with a moderate number of setae. Proximal two thirds of cerci conical, distal third a bit slender, nearly cylindrical. Cuticle glabrous, with a very slight scaly pattern.

Exterior part of the trichobothria’s pit covered by scales, which present spiny margins at the ventral side ( Fig. 1 G, H). There are two larger spines: a straight and very long one and a not so long, thicker and curved one ( Fig. 1 H).

Legs. First pair of legs a bit less than half as long as following pair. Tarsus of legs 10–12 of females with two ventral longitudinal rows of 7–8 splinter–like setae ( Fig. 1 I, arrow). These modified setae are very short and wide, wider at the most distal point and have the shape of an inverted triangle. There are 7 pairs of fully developed coxal sacs at the base of legs 3–9.

Styli of posterior pairs of legs 4.5 times as long – including the apical seta – as wide and 1.4 times as long as width of tarsus. Pubescence rather sparse, setae distributed in longitudinal rows (figs. 1E, F). Apical seta 0.75 times as long as the stylus without the seta.

Differential diagnostic. This species is very similar to Hanseniella tenella Ribaut 1914 : the morphology of the tergites is almost identical. S. congolensis can be differentiated from the latter species by (i) the absence of a reticulate pattern in the frontal part of the head, (ii) the presence of a single pair of lateral macrochaetae on the penultimate tergite, (iii) the absence of setae on the posterior margin of the same tergite and (iv) the presence of two rows of splinter–like setae on the tarsus of the three last pairs of legs of the females.

Figures

FIGURE 1. SEM micrographs of Scolopendrelloides congolensis n. sp., holotype and paratype from the type locality. A, whole body; B, head, dorsal view; C, tergites 1 – 3 of the holotype. D, head and first three tergites of paratype. E and F, leg 9 and stylus (detail) of the holotype, frontal view. G and H, trichobothria of the holotype (G) and the paratype (H), lateral view. I, tergites 14 and 15, cerci and last pairs of legs of the holotype, dorsal view. Both rows of splinter – like setae are visible on the tarsus of the last pair of legs (arrow).