Orthochirus arabicus, Ythier & Lourenço, 2023

Ythier, Eric & Lourenço, Wilson R., 2023, Two new scorpionspecies from Central SaudiArabia (Scorpiones: Buthidae), Faunitaxys (London, England) 11 (8), pp. 1-8 : 3-4

Orthochirus arabicus sp. n.

(Fig. 8-15, Tab. I)

ZooBank:http://zoobank.org/ BA992DE2-58CE-474F-811A-641FA7DAF88D

Holotype, ♀, Saudi Arabia, Central region , Mahazat as-Sayd Reserve (22.26931°N 41.83913°E), 250 km E of Taif, on the road between Djeddah and Ryadh, between 900-1100 m a.s.l., III-V/1990 (C. Launay / National Wildlife Research Center), MNHN.

Etymology. – The specific name refers to SaudiArabia, where the new species occurs.

Diagnosis. – Scorpion of small size when compared to other known species of the genus, reaching a total length of 22 mm. General coloration yellowish brown with darker variegated pigmentation throughoutbody and appendages.Anterior margin of carapace almost straight. Metasomal segments I-II wider than long, III-V longer than wide; ventral aspect of segment V without any granulations.Fixed and movable fingers of pedipalps with 8-9 rows of granules; outer accessory granules present next to the seven distal rows. Pectines with 17-17 teeth in female, male unknown. Trichobothriotaxy: A-β (Beta) neobothriotaxy-minorante; trichobothrium d 2 absent on femur. Trichobothrium i 2 of femur reduced (Vachon, 1974). Chela manus with trichobotrium Esb proximal to Esb; fixed finger with trichobotrium dt and et on same level.

Description (based on female holotype, measurements in Table I).

Coloration. – Basically yellowish brown with darker variegated pigmentation throughout body and appendages. Prosoma: carapace yellowish brown with blackish pigmentation anteriorly; median and lateral eyes surrounded by black pigment. Mesosoma: yellowish brown with dark brown variegated pigmentation on carinae and granulations. Metasomal

3 - 4. Chela. 3. Dorso-external aspect. 4. Ventral aspect. 5. Femur, dorsal aspect. 6 - 7. Patella. 6. Dorsal aspect. 7. External aspect.

segments yellowish brown to reddish brown with darker zones over the carinae; telson yellowish with brownish variegated pigmentation; aculeus yellowish at the base and reddish at the tip. Venter: sternites yellowish with greyish to brownish variegated pigmentation, darker on VI; genital operculum and pectines yellowish with greyish pigmentation. Chelicerae yellowish with blackish variegated spots covering the entire surface; fingers yellowish with reddish teeth. Pedipalp femur and patella yellowish brown almost entirely covered with blackish variegated pigmentation; chela yellowish brown with some brownish pigmentation on manus; fingers pale yellow; oblique rows of granules on fingers pale red. Legs yellowish brown with brownish variegated pigmentation, lighter on distal segments.

Morphology. –Prosoma:carapace witha thingranulationon anterior and posterior zones; central zone around ocular tubercle almost smooth; anterior margin almost straight. Carinae and furrows weakly marked. Median ocular tubercle anterior to the centre of the carapace; median eyes separated by one and half ocular diameter. Three pairs of lateral eyes. Sternum subtriangular to subpentagonal, longer thanwide. Mesosoma:tergiteswitha thin granulation; median carina weak to vestigial in all tergites. Tergite VII pentacarinate with strong carinae. Venter: sternites almost smooth, slightly chagrined, with small slit-like spiracles; VII with four carinae weakly marked. Genital operculum divided longitudinally into two sub-oval plates. Pectines: pectinal tooth count 17-17; basal middle lamellae not dilated. Metasomal segments rounded; I-II wider than long, III-V longer than wide. Carinae moderately marked; granulations weakly marked, almost smooth; segments I-II with ten carinae; segment III with 8 carinae; segments IV-V with dorsal carinae and punctuations; intercarinal spaces smooth dorsally, weakly granular to almost smooth laterally and ventrally; ventral aspect of segment V smooth between punctuations, without

granulations; the distal region along the anal arc slightly chagrined. Telson smooth, with some minor

punctuations; aculeus shorter than the vesicle and moderately curved; subaculear tooth absent. Cheliceral

dentition characteristic of the family Buthidae (Vachon, 1963) ; movable finger with weakly marked basal

teeth; ventral aspect of both finger and manus with thin setae. Pedipalps: femur with five moderate to strong

carinae, granular; patella with five weakly marked carinae; chela without carinae, smooth. Fixed and

movable fingers with 8-9 rows of granules; outer accessory granules present next to the seven distal rows.

Trichobothriotaxy:A-β;neobothriotaxy‘minorante’;absence of trichobothria d 2 and e 1 on femur (Vachon,

1974, 1975); chela manuswith trichobotrium Esb proximal to Est; fixed finger with trichobotrium dt and

et on same level. Legs: tarsus with two rows of setae ventrally.Tibial and pedal spurs moderately marked.

Relationships. – Orthochirus arabicus sp. n. can be distinguished from the other Middle

Eastern species of Orthochirus , and in particular from O. negebensis ( Fig. 18 ), which presents

the closest geographic distribution ( Israel, Jordan, Sinai), notably by the following characters:

(i) a smaller size (25-40 mm in O. negebensis ),

(ii) a paler coloration (black to blackish olive in O. negebensis ),

(iii) anterior margin of carapace almost straight (convex in O. negebensis ),

(iv) female metasomal segments III-V longer than wide (wider than long in female O. negebensis ),

(v) chela manus with trichobotrium Esb proximal to Est (distal in O. negebensis ),

(vi) a totally allopatric geographic distribution.

Most of these characters also distinguish the news species from O. innesi ( Fig. 19-20 ), which also

presents a totally allopatric geographic distribution (north of Egypt and possibly the north ranges of

Libya, Tunisia and Algeria). It is probable that some of the Orthochirus populations occurring in

Saudi Arabia, notably in the centre of the country, can be assigned to O. arabicus sp. n.

NB: during the reviewing process of this manuscript, a new Orthochirus species was

described from Saudi Arabia ( Kovařík & Just, 2022), in the Hajrah District, 5 km NW of

At-Tinah (20.1107947°N 40.8434278°E), 1400 m a.s.l. O. katerinae Kovařík & Just, 2022

was described on the basis of 14 males (12 adults and 2 juveniles) and considered to be

related but separate species from O. negebensis . Orthochirus arabicus sp. n. can be

distinguished from this species notably by the following characters:

Figures

Fig. 18. Orthochirus negebensis Shulov & Amitai, 1960 from Israel, female with pro-juveniles.

Fig. 19-20. Orthochirus innesi Simon, 1910, ♀ holotype from Egypt, habitus. 19. Dorsal aspect. 20. Ventral aspect.