Orthochirus atarensis Lourenço et Leguin, 2011

Lourenço, Wilson R. & Leguin, Elise-Anne, 2011, Further considerations on the species of the genus Orthochirus Karsch, 1891 from Africa, with description of three new species (Scorpiones: Buthidae), Euscorpius 123 (123), pp. 1-19 : 12-18

Orthochirus atarensis Lourenço et Leguin , sp. n.

( Figs. 17−21 , 26 , 31−32 , 37 ; Tab. 1)

Type material: Mauritania, Atar , 44 km past Chingetti towards Atar (20.54587°N, 12.68945°W), 703 m, 7/I/2005 (P. Geniez), male holotype. N Azougui (20.5739°N, 13.0961°W), 270 m, 12/XI/2006 (P. Geniez), 1 female, 1 male juvenile paratypes. Deposited in the Muséum national d’Histoire naturelle, Paris .

Etymology: specific name refers to the locality in which the holotype was collected.

Ecological note: the two sites where Orthochirus atarensis sp. n. was collected correspond to an endemic area in Mauritania. A new endemic species of lizard, Pristurus adrarensis Geniez & Arnold, 2006 was also recently collected and described from this same area of Adrar Atar (Geniez & Arnold, 2006).

Diagnosis

Small sized scorpions, reaching a total length of 21 mm for male and 23 mm for female. General coloration brownish-yellow to dark brown. Anterior margin of carapace straight in male, slightly convex in female. Ventral aspect of metasomal segment V without granulations posteriorly. Fixed and movable fingers with 9/9 rows of denticles; accessory denticles present. Pectines with 17-18 teeth in male and 15-16 teeth in female. Trichobothriotaxy: A-β; neobothriotaxy ‘minorante’ in male, orthobothriotaxy in female.

Relationships: Orthochirus atarensis sp. n. can be distinguished from the other species of Orthochirus , and in particular from Orthochirus innesi by the following characters:

(i) smaller overall size (see Table 1), (ii) anterior margin of carapace straight in male, (iii) presence of trichobothrium d 2 of femur in female, (iv) coloration pattern very dark, (v) carapace and tergites weakly granular.

Description based on male holotype and paratypes.

Measurements in Table 1.

Coloration. Basically brownish-yellow. Prosoma: carapace dark brown; anterior margin yellowish-brown; median and lateral eyes surrounded by black pigment. Mesosoma: brownish to brownish-yellow; carinae and granulations dark brown. Metasomal segments dark brown; telson reddish-brown; aculeus yellowish with a reddish tip. Metasomal carinae marked with blackish.

Venter yellowish-brown; pectines pale yellow. Chelicerae yellowish, with dark variegated spots; fingers dark brown. Pedipalps, femur and patella dark brown; chela yellowish. Legs yellowish with diffused dark brown spots.

Morphology. Carapace weakly granular; anterior margin straight in male, with a slight convexity in female. Carinae and furrows moderate to weak. Median ocular tubercle slightly anterior to the centre of the carapace; median eyes separated by about one ocular diameter. Three pairs of lateral eyes. Sternum subtriangular to subpentagonal, wider than long. Mesosoma: tergites with moderate to weak granulations; median carina weak in all tergites. Tergite VII pentacarinate with moderate carinae. Venter: genital operculum weakly elongated, divided longitudinally into two suboval plates. Pectines: pectinal tooth count 17−18 in male, 15−16 in female; basal middle lamellae of each pecten not dilated. Sternites almost smooth with small slit-like spiracles; VII with four carinae moderate. Metasoma: segments rounded, with carinae moderately marked; granulations weakly marked; segments I to III with ten carinae; segments IV and V with punctuations; ventral aspect of segment V without granulations in the distal region. Intercarinal spaces smooth dorsally; weakly granular laterally and ventrally. Telson smooth with a few punctuations; aculeus as long as the vesicle and moderately curved; subaculear tooth absent. Cheliceral dentition characteristic of the family Buthidae (Vachon, 1963) ; movable finger with basal teeth distinct; ventral aspect of both finger and manus with thin setae. Pedipalps: femur with five strong carinae, granular; patella with 6−7 weakly marked carinae; chela without carinae, smooth. Fixed and movable fingers with 9/9 rows of denticles. Trichobothriotaxy: A-β; neobothriotaxy ‘minorante’ in male, orthobothriotaxy in female (Vachon, 1974, 1975). Legs: tarsus with two rows of setae ventrally. Tibial and pedal spurs moderately to strongly marked.

Distribution: Only known from the type locality.

Key to the African species of Orthochirus

1. Ventral aspect of metasomal segment V with granulations posteriorly …………………...…. O. innesi (1). Ventral aspect of metasomal segment V without granulations posteriorly ………………………………..2 2. Pectines with more than 20 teeth…………..………. …………………………... O. cloudsleythompsoni sp. n. (2). Pectines with less than 20 teeth ……………...……3 3. Chela dark brown; genital operculum elongated, divided longitudinally into two suboval plates ……… ……………………………..……………….. O. aristidis (3). Chela yellowish; genital operculum not elongated .. ………………………………………………………… 4 4. Genital operculum small with suboval to rounded plates; anterior margin of male carapace with a moderate convexity; trichobothrium d 2 of femur absent in female …………………………………... O. hoggarensis sp. n. (4). Genital operculum moderate with suboval plates; anterior margin of male carapace straight; trichobothrium d 2 present in female …...…. O. atarensis sp. n.

Remarks About the Geographical Distribution of the African Species

Orthochirus aristidis has been the subject of few citations in the recent literature about scorpions (El-Hennawy, 1992; Fet & Lowe, 2000). This was probable associated to the incertitude about its taxonomic position, since the type material was misleading for more than a century. The distribution of this species can now be confirmed for the South of Egypt, Sudan, Djibouti and possibly Ethiopia.

In contrast with O. aristidis , Orthochirus innesi was cited very often in the literature, and recorded for most regions of North Africa. This was largely due to the taxonomic decisions synthesized by Vachon (1952) in his studies of the North African fauna of scorpions. Studies of more southern populations of the Sahara desert (this publication) show, however, that several of these populations have been misidentified by Vachon (195 2). Therefore, it is quite possible that O. innesi has a distribution limited to the north of Egypt, Libya, Algeria and Tunisia. Part of the old material listed by Vachon (1952) is still present in the collections of the Museum in Paris. This material, however, is poorly preserved and the data available for their originals localities is often imprecise. New collections will be required to define the exact range of distribution of the species. The presence of this species in the Middle East most certainly can be rejected. Examination of one female from southern Sinai (( Egypt, S of Sinai, Wadi Feiran, 3/IX/2001 (H. El-Hennawy)) confirms that the species present there is Orthochirus scrubiculosus . This confirms the identification done by Levy & Amitai (1980).

The population of Hoggar and Tassili Mountains in the south of Algeria, was tentatively referred to O. innesi by Vachon (1952). Subsequently, in a more precise study on the scorpions of this region, Vachon (1958) confirmed this population as O. innesi . At present, this population is described as a new species, Orthochirus tassili sp. n., probably endemic to this mountain region.

The first record of an Orthochirus species from Morocco, is the one proposed by Vachon (1954) for specimens from Aouinet Torkoz in the southern region of this country. The female specimen reported was in fact collected and determined by J. B. Panouse. The subsequent ‘first record’ proposed by Kovařík (1995), was evidently erroneous. More recent field trips to the region of Aouinet Torkoz carried out by the senior author, allowed the collection of more specimens of Orthochirus from this area. These specimens are yet under biological study, but we can already suggest that this population is distinct both from O. innesi , and O. cloudsleythompsoni sp. n. described from Tata.

Orthochirus innesi was also recorded by Vachon (1950) from Mauritania in a single line of his key to the scorpions of North Africa. This citation, was again repeated by Vachon (1952), but in his much more completed study of the scorpions from Mauritania none species of Orthochirus are listed. The new species described here, O. atarensis sp. n., is markedly different from O. innesi , in particular by the orthobothriotaxic trichobothrial pattern of females.

Subsequent studies on the southern Saharan populations of Orthochirus should revel yet new species to be described.

Figures

Figures 17−20: Orthochirus atarensis sp. n., male holotype and female paratype, dorsal and ventral aspects.

Figure 21: Orthochirus atarensis sp. n., male holotype (alive) in the field (photo by P. Geniez).

Figures 22−26: Disposition of the granulation over the dentate margin of the movable finger. 22. Orthochirus aristidis, female from Nubia. 23. Orthochirus innesi, female from Wadi Degla near Cairo. 24. Orthochirus tassili sp. n., female paratype. 25. Orthochirus cloudsleythompsoni sp. n., male holotype. 26. Orthochirus atarensis sp. n., female paratype.

Figures 27−32: Femur, dorsal aspect, showing trichobothrial pattern. 27. Orthochirus aristidis, female from Nubia. 28. Orthochirus innesi, female from Wadi Degla near Cairo. 29. Orthochirus tassili sp. n., female paratype. 30. Orthochirus cloudsleythompsoni sp. n., male holotype. 31−32. Orthochirus atarensis sp. n., male holotype and female paratype.

Figures 33−38: Sternum and genital operculum. 33. Orthochirus aristidis, female from Nubia. 34. Orthochirus innesi, female from Wadi Degla near Cairo. 35. Orthochirus tassili sp. n., female paratype. 36. Orthochirus cloudsleythompsoni sp. n., male holotype. 37. Orthochirus atarensis sp. n., female paratype. 38. Orthochirus innesi, female from Wadi Degla near Cairo. Ventral aspect of metasomal segments I−V and telson, showing granulations on segment V.