Opisthacanthus milloti, Lourenço & Goodman, 2008

Lourenço, Wilson R. & Goodman, Steven M., 2008, Scorpions of the Réserve spéciale d’Ankarana, Madagascar, with particular reference to cave-dwelling animals and the description of two new species (Arachnida, Scorpiones), Zoosystema 30 (3), pp. 665-679 : 669-673

Opisthacanthus milloti n. sp.

( Figs 2-4 )

TYPE MATERIAL. — Madagascar. Antsiranana Province, Réserve spéciale d’Ankarana, in the entry of the grotte des Chauve-souris, found resting on soil under stone, IX.2001, W. R. Lourenço coll., 1 ♂ holotype, 1 ♂, 1 ♀ paratypes ( MNHN).

DIAGNOSIS. — Small size scorpions: males 36 mm and female 32 mm in total length. Coloration reddish-yellow to reddish-brown with some blackish areas over pedipalp carinae. Pectines with 6-6 teeth in males and female. Hemispermatophore small, with the distal lamina weakly enlarged and longer than that observed for O. darainensis ( Fig. 2C ). Female genital operculum large, with an almost oval-shape, and lacking incision in the base ( Fig. 3B ). Trichobothrial pattern of type C, orthobothriotaxy.

The new species can be distinguished from O. darainensis , described from the more southerly Loky-Manambato (= Daraina) region, by the following characters: 1) smaller global size; 2) distinct morphometric values (see Table 1); 3) presence of four moderate carinae on sternite VII; and 4) distal lamina of hemispermatophore narrower and elongated.

ETYMOLOGY. — Patronym in honour of the late Prof. Jacques Millot, who devoted many years of his life to the study of the Malagasy fauna.

DESCRIPTION

(based on ♂ holotype and ♀ paratype)

Coloration

Basically reddish-yellow to reddish-brown with some blackish areas on the pedipalp carinae. Carapace reddish-brown with a paler section on the posterior edge; median and lateral eyes surrounded with black pigment.Tergites reddish-brown with two vestigial longitudinal pale yellow spots. Metasomal segments reddish-brown, with some vestigial yellowish variegated areas; vesicle yellowish,with lateral reddish bands on males, but absent on female; aculeus dark reddish. Chelicerae reddish-brown; base of fingers blackish; the whole surface with diffuse variegated dark spots; fingers blackish with reddish teeth. Pedipalps reddish-brown; most carinae blackish. Venter: sternites brownish-yellow; coxapophysis and sternum reddish-brown; pectines and genital operculum yellowish; legs reddish-yellow with diffused dark spots.

Morphology

Carapace smooth with intense punctation; lateral edges, in males, with some minute granulations; furrows shallow. Anterior margin with a strong concavity reaching as far as the level of the second lateral eye ( Fig. 2A ). Median ocular tubercle flattened and almost in the center of the carapace; median eyes moderate to small, separated by less than one ocular diameter; three pairs of lateral eyes. Sternum pentagonal, wider than long. Genital operculum formed by two semi-oval plates in males, and one single large, almost oval-like shaped plate in females ( Fig. 3 ). Tergites with one vestigial median carina, and with intense punctation. Pectinal tooth count 6- 6 in male holotype and in female paratype. Sternites smooth and shiny, with punctations laterally; VII with four moderate carinae. Metasomal segments I to V longer than wide with sparse granulations. All carinae weakly developed in segments I-IV of male, moderately evident in female; segment V slightly rounded with spinoids granules on ventro-lateral and ventro-median carinae. All segments with moderate setation, more pronounced in males. Telson with a pear-like shape; smooth and covered with strong setation ( Fig. 2D, E ). Pedipalps: femur with dorsal internal, dorsal external, ventral internal, and ventral external carinae strong, tuberculate; dorsal face with moderately marked granulation; ventral face with a thin granulation; internal face moderately granulose. Patella with internal and external faces weakly granulated; dorsal and ventral faces smooth and lustrous, with punctations; dorsal internal, dorsal external, ventral internal, ventral external, and external carinae moderate to strong; other carinae less well-marked. Chela strongly

A granular on dorso-internal and external faces; other faces punctated; dorsal marginal, external secondary, ventro-internal and ventral median carina moderate to strong; other carinae less well-marked. Chelicerae typical of Scorpionoidea ( Vachon 1963); teeth sharp ( Fig. 2B ). Trichobothriotaxy type C ( Fig. 4 A-H); orthobothriotaxic ( Vachon 1974). Legs: tarsi of legs III and IV with two prolateral and two retrolateral spines, surrounded by a few long setae. Spurs moderate. Hemispermatophore as in Figure 2C with the distal lamina elongated and weakly enlarged.

Ecology and distribution

This new species is only known from its type locality. Because it was collected at the cave entrance only, it is not to be considered as a troglobitic element.

Figures

FIG. 2. — Opisthacanthus milloti n. sp., ♂ holotype and ♀ paratype:A, carapace; B, chelicera; C, hemispermatophore external aspect (♂); D, E, metasomal segment V and telson, lateral aspect (♂ and ♀). Scale bars: 2 mm.

FIG. 3. — Opisthacanthus milloti n. sp., ventral aspect, showing coxapophysis,sternum,genital operculum,pectines and sternite III: A, ♂ holotype; B, ♀ paratype. Scale bar: 2 mm.

FIG. 4. — Opisthacanthus milloti n. sp., ♂ holotype, trichobothrial pattern: A-C, chela dorso-external, external and ventral aspects; D, femur, dorsal aspect; E, fixed finger, internal aspect; F-H, patella, dorsal, external and ventral aspects; I, cutting edge of movable finger with rows of granules. Scale bars: 2 mm.