Opisthacanthus (Monodopisthacanthus) lourencoi, Ythier, 2022

Ythier, Eric, 2022, A new species of Opisthacanthus Peters, 1861 from the dry savannah formations of southern Madagascar (Scorpiones: Hormuridae), Faunitaxys (New York, N. Y.) 10 (45), pp. 1-7 : 2-4

Opisthacanthus (Monodopisthacanthus) lourencoi sp. n.

(Fig. 1-10, Tab. I)

ZooBank: http://zoobank.org/ 87AE7069-56FC-49F5-9E4F-3AFB379D2BDC

Holotype, ♀, Madagascar, Beraketa , 21/VII/1964 (J. Poulard), deposited in the MHNL (47000909).

Paratypes (5 ex.):

- 1 ♀, 1 pre-adult ♀, 1 pre-adult ♂, Madagascar, Beraketa , 21/VII/1964 (J. Poulard) ,

deposited in the MHNL (47000910, 47000911 and 47000914, respectively).

- 1 pre-adult ♀, 1 juvenile ♀, Madagascar, Beraketa , VIII/1962 (L. Lumaret & J.-P.

Lumaret), deposited in the MHNL (47036299 and 47036298, respectively).

Etymology. – The specific name honours my colleague and mentor Dr. Wilson

R. Lourenço, for his important contribution to the study of scorpions of the genus Opisthacanthus , as well as of the scorpion fauna of Madagascar.

Diagnosis. –Scorpion of medium size with a total length of 45-47 mm for the females. Pre-adult male has a total length of 32 mm so adult male probably reaches similar size as female. General coloration brownish with some dark variegated zones on the carapace, tergites and metasomal segments. Pectines with 7-7 teeth in both sexes. Female genital operculum with an almost oval shape, without any incision as its base. Trichobothrial pattern of type C,

orthobothriotaxy; trichobothrium em 2 distal to em 1 on patella.

Description (based on female holotype. Measurements in Table I).

Coloration. – Basically brownish with some dark variegated zones on the carapace, tergites and metasomal segments. Carapace reddish brown with dark variegated spots; median and lateral eyes surrounded with dark pigment. Tergites reddish brown with vestigial dark variegated spots. Metasomal segments yellowish brown with dark variegated spots; vesicle yellowish; aculeus dark reddish. Chelicerae yellowish with diffuse blackish variegated spots on the whole surface; fingers yellowish with the base marked with blackish spots, teeth reddish. Pedipalps reddish brown with carinae dark brown to blackish. Venter and sternites reddish yellow. Legs yellowish brown.

Fig. 1-2. Opisthacanthus lourencoi sp. n., Morphology. – Prosoma: carapace almost smooth with some minute granulations on lateral sides; the whole surface minutely punctuated; furrows shallow. Anterior ♀, holotype, habitus (dried specimen). margin with a strong concavity almost reaching the level of the third lateral eye. 1. Dorsal aspect. 2. Ventral aspect.

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3. Metasomal segment V and telson, lateral aspect. 4-10. Trichobothrial pattern. 4-6. Chela. 4. dorsal. 5. external. 6. ventral. 7-9. Patella. 7. dorsal. 8. external. 9. ventral. 10. Femur, dorsal.

Median ocular tubercle flattened and almost in the centre of the carapace; median eyes moderate, separated by half of one ocular diameter; three pairs of large lateral eyes. Sternum pentagonal, wider than long. Genital operculum with an almost oval shape, without any incision as its base. Tergites with only a vestigial median carina, smooth except some minute granulation on VII; lateral surface of tergites minutely punctuated. Pectinal tooth count 7- 7 in female holotype. Sternites smooth and shiny, with elongated spiracles; VII with two vestigial carinae and minute punctuations on lateral sides. Metasomal segments I to V longer than wide, with some minute but intense granulations. All carinae weakly marked on segments I-IV; segment V rounded with some spinoid granules on the ventral surface. All segments with moderate to strong chetotaxy. Telson with a pearlike shape; smooth and covered with strong chetotaxy; aculeus moderately curved. Pedipalps: femur with dorsal internal, dorsal external, ventral internal and ventral external carinae strong, tuberculate; dorsal and ventral faces with thin granulation; internal and external faces moderately granulated. Patella with dorsal internal, ventral internal, ventral external and external carinae strong; other carinae less marked; dorsal, internal and external faces moderately granulated; ventral face with minute granulation and punctuation. Chela with dorsal marginal, external secondary, ventral internal and ventral median carinae strong; other carinae less marked; dorsal, internal and external faces strongly granulated; ventral face with minute granulation and punctuation. Fingers with two primary rows of denticles fused at the base. Chelicerae typical of Scorpionoidea (Vachon, 1963); teeth sharp. Trichobothriotaxy of type C; orthobothriotaxic ( Vachon, 1974); trichobothrium em 2 distal to em 1 on patella. Legs: tarsi with two lateral rows of spines, surrounded by a few long setae; spurs weak to moderate. Measurements in Table I.

Relationships. – Byits generalmorphology, Opisthacanthus lourencoi sp. n. shows several characters which associate it to O. lucienneae , a speciesknown from dry forests and spiny bush of the extreme south and south-east of Madagascar.

The new species can however be distinguished from O. lucienneae notably by the following main features:

(i) an overall darker coloration, reddish brown to yellowish brown (reddish yellow to yellowish in O. lucienneae );

(ii) concavity on anterior margin of carapace deeper;

(iii) two vestigial carinae on sternite VII (acarinate in O. lucienneae );

(iv) genital operculum with an almost oval shape (slightly heart-like shaped in O. lucienneae );

(v) femur, patella and chela more granulated;

(vi) a slightly bigger overall size and some different morphometric ratios, notably a more rounded vesicle and larger chela manus (see Tab.1);

(vii) on patella, trichobothrium em 2 distal to em 1 (at same level in O. lucienneae ).

O. lourencoi sp. n. can also be distinguished from the two other species inhabiting dry to semi-dry formations in the south-west of Madagascar, namely O. madagascariensis and O. maculatus , notably by the following main features:

(i) an overall size smaller than O. madagascariensis and bigger than O. maculatus and some different morphometric ratios, notably a more rounded vesicle and larger chela manus (see Tab. 1);

(ii) two vestigial carinae on sternite VII (acarinate in both species);

(iii) genital operculum with an almost oval shape, without any incision as its base (heart-like shaped plate with a small incision at its base in both species);

(iv) leg tarsi with two lateral rows of spines (three rows of spines in both species).

Distribution and ecology. – Opisthacanthus lourencoi sp. n. is only known from its type locality, Beraketa, in the Androy region, in the south of Madagascar ( Fig. 11-12). It is located at the foot of the western part of the Ivakoany Massif, in a wide arid plain covered by dry savannah formations ( Fig. 13) interspersed with sisal ( Agave sisalana ) fields. The climate is hot semi-arid (type "BSh" according to Köppen-Geiger classification) with mean temperature going from 23°C (March) to 28°C (July) and mean precipitation going from 6 mm (May) to 234 mm (January).