Mesobuthus longichelus Sun & Zhu 2010

Description. Based on female holotype.
Coloration. Basically brownish-yellow. Prosoma: carapace brownish-yellow, with only blackish anterior median carinae, other carinae without pigment; eyes surrounded by black pigment. Mesosoma: brownish-yellow; segments I to VI with a distinct blackish longitudinal stripe in the middle, lateral carinae without pigment. Metasoma: segment I pale brownish-yellow; segments II to V yellow; ventral and lateral surfaces of segment V with inconspicuous variegated black pigment; vesicle yellow and aculeus dark reddish to blackish on its extremity. Venter pale brownish-yellow, except for the pectines which are pale yellow. Chelicerae: pale brownish-yellow without any variegated pigmentation; teeth dark reddish to brownish. Pedipalps: femur, patella and manus reddish-yellow, without pigment; fingers yellow; rows of granules on dentate margins of the fingers blackish-brown. Legs: pale yellow without pigment.
Morphology. Prosoma: anterior margin with a very weak median concavity; carinae moderately strong, granular and granules relatively minor; central median carinae directly connected with posterior median carinae and lateral median carinae by a row of sparse granules; posterior median carinae terminating distally in a small spinoid process which extends slightly beyond the posterior margin of the carapace; intercarinal surfaces smooth, except for the surfaces between central median carinae and posterior median carinae, which are globally, sparsely and finely granular; the extercarinal surfaces with sparse small granules; the surfaces between anterior median carinae and lateral eyes coarsely granular; furrows moderate. Median ocular tubercle slightly anterior to the centre of carapace; median eyes separated by almost 1.75 ocular diameters; three pairs of lateral eyes.
Mesosoma: Tergite: I to VI tricarinate; lateral carinae on I-VI moderate, granular; the median carina on I weakly, median carinae on II-VI moderate, granular; each carina on I-VI terminating distally in a small spinoid process which extends beyond the posterior margin of tergite, except the median carina on I; the intercarinal surfaces relatively smooth, except for the posterior margins with sparse and fine granules; exterior surfaces moderately to coarsely granular; VII pentacarinate; two pairs of lateral carinae moderate to strong; median carinae present on proximal half, moderate; the intercarinal surfaces smooth. Sternites: III-VII smooth; lateral margins slightly serrate; VII with four weakly marked carinae, granular. Pectines: moderately long; pectinal teeth 22-23 (see variation on table I).
Metasoma: Segments I with 10 complete carinae, segment II-IV with 8 complete carinae; all carinae moderately strong, granular, except the dorsal carinae, serrate; median lateral carinae complete on segment I, only with sparse granules and covered 1/2-2/3 length of segment on II and obsolete, remaining 1-2 granules at distal end on III. Intercarinae surfaces on segments I to IV smooth, except the surfaces between dorsal and dorsolateral carinae on segment I, which are weakly granular. Segment V pentacarinate; ventral carina moderate, granular; ventrolateral carinae strong, serrate, becoming strongly marked posteriorly and with 2-3 markedly large and extroversive lobed granules; dorsolateral carinae weakly developed, obsolete posteriorly; dorsal and lateral surfaces smooth, ventral surface with sparse large granules. Telson smooth dorsally and weakly granular ventrolaterally; aculeus long, markedly more than a half of telson length (see variation on table I).
Chelicerae: Dentition as defined by Vachon (1963) for the family Buthidae.
Pedipalps: Trichobothrial pattern: Orthobothriotaxic A-? (Vachon, 1974, 1975). Femur pentacarinate, moderately to strongly granular; ventrointernal carina with spinoid granules. Patella with seven carinae, very weakly to moderately granular. Intercarinal surfaces on both segments smooth. Chela smooth without carinae; long and slender (table I). Dentate margins of movable and fixed fingers with 12 and 11 oblique rows of granules respectively; outer accessory denticles becoming smaller from base to tip, and smaller than inner accessory denticles on the tip.
Legs: Tarsus ventrally with two long longitudinal rows of setae; tibial spurs present on legs III and IV, moderately marked; pedal spurs present and moderately developed on all legs.

Ecology. The new species was found mainly in habitats composed of very arid and strongly desertified grassland, under very big and oval rocks. This region is constituted by alluvial plains, and is located about 10 km north of the Tianshan Mountains. The area is quite droughty during the whole year, and even during summer. The vegetation is composed of scarcely shrubs, and is strongly xerophytic.