Tityus (Atreus) crassicauda, Lourenco, Wilson R. & Ythier, Eric, 2013

Lourenco, Wilson R. & Ythier, Eric, 2013, The remarkable scorpion diversity in the Ecuadorian Andes and description of a new species of Tityus C. L. Koch, 1836 (Scorpiones, Buthidae), ZooKeys 307, pp. 1-13 : 2-7

Tityus (Atreus) crassicauda sp. n. Figs 1-18

Material examined.

Ecuador, Pichincha Province, Tandayapa, 2200 m, VIII/2012 (G. Onore & I. Tapia leg.). Inside of Lauraceae rotten logs.

Male holotype and female paratype. Deposited in the Muséum national d’Histoire naturelle, Paris.

Etymology.

Specific name refers to the strongly enlarged posterior metasomal segments.

Diagnosis.

Scorpions of medium size in relation to other species within the genus. Total length in male and female, 51.9 and 50.5 mm, respectively. General coloration reddish-brown with darker blackish zones; carapace and tergites with three longitudi nal brownish stripes, separated by yellow zones. Metasomal segments flattened, comparatively to other species of the group; segments IV and V very strongly enlarged, especially in the male holotype. Dorsal carinae of metasomal II to IV terminating distally with two very strong spinoid granules, more distinct on the female paratype. Pectines small with 15-15 teeth on male and 15-14 on female; basal piece of the middle lamella strongly dilated on female, and oval in shape. Cutting edges of fixed and movable fingers of pedipalp chela with 12-13 and 12-14 rows of granules on the male and female, respectively.

Relationships. The new species is clearly allied to Tityus forcipula (Gervais, 1843) and other associated species such as Tityus spinatus Pocock, 1898 and Tityus cuellari Lourenço, 1994, species also known from the Colombian and Ecuadorian Andes and, previously defined as part of the Tityus forcipula complex (see Lourenço 1984 for details). It can, however, be distinguished from all these species and in particular from Tityus forcipula by a number of features: (i) a distinct pattern of coloration and pigmentation, with brownish longitudinal stripes on the carapace and tergites, which are absent from the other species, (ii) sternites III to VII with a very strongly marked granulation but a moderately marked setation; granulations are less marked on the other species, (iii) metasomal segments strongly flattened and very strongly enlarged, especially in the male holotype; less enlarged in the other species, (iv) tergites with only moderately marked granulation, (v) pedipalp segments and chela are smooth to lustrous; somewhat granular in the other species.

Description based on male holotype and female paratype (measurements in Table 1).

Coloration. Reddish-brown with darker, blackish areas. Prosoma: carapace reddish-brown, with yellowish zones between posterior median carinae. Mesosoma: reddish-brown with three brown to blackish longitudinal stripes extending from the posterior zone of the carapace and over tergites I to VII. Metasomal segments I to III reddish-brown, with dark to blackish carinae; IV and V reddish-brown dorsally, blackish laterally and ventrally. Vesicle: brownish-black; aculeus yellowish. Venter is reddish-brown, with some yellowish zones. Chelicerae yellowish-brown, with a very dark thread of variegated spots; fingers dark; teeth reddish. Pedipalps: reddish; fingers blackish, with extremities yellowish. Legs reddish-yellow to reddish-brown, with some diffuse and discrete fuscous spots; tarsi yellowish.

Morphology. Carapace moderately to strongly granular; anterior margin with a moderately marked concavity. Anterior median superciliary and posterior median carinae moderate to strong. Furrows moderately to strongly deep. Median ocular tubercle distinctly anterior to the centre of carapace. Eyes separated by a little more than one ocular diameter. Three pairs of lateral eyes. Sternum triangular. Mesosomal tergites moderately granular. Median carina strong on all tergites. Tergite VII pentacarinate. Venter: genital operculum divided longitudinally, forming two semi-oval plates. Pectines small; pectinal tooth count 15-15 in male holotype and 15-14 in female paratype; basal piece of the middle lamellae of the female pectines oval shaped and strongly dilated. Sternites very strongly granular, in particular on male holotype; spiracles moderately elongated; VII with four moderately to strongly marked carinae. Metasomal segments strongly flattened dorsally; IV and V very strongly enlarged, especially in the male holotype; segments I and II with ten carinae; III and IV with eight carinae, crenulate; V with five carinae. Dorsal carinae on segments II to IV with two very strong spinoid granules, distally. Lateral inframedian carinae on segment I complete, crenulate; on II almost complete; absent from III and IV. Ventrolateral carinae strong, crenulated; ventral submedian carinae strongly crenulate. Intercarinal spaces moderately granular. Segment V with weak dorsolateral carinae; ventrolateral and ventromedian carinae strong, crenulate. Lateral intercarinal spaces moderately to strongly granular. Telson moderately granular, with a long, strongly curved aculeus. Dorsal surface smooth; ventral surface weakly granular; subaculear tooth strong and spino-rhomboidal in shape. Cheliceral dentition characteristic of the family Buthidae (Vachon, 1963); movable finger with two basal teeth well distinct; ventral aspect of both fingers and manus with long, dense setae. Pedipalps: femur pentacarinate; patella with seven carinae; chela with nine carinae, more distinct on female paratype; all faces with only a few granules; smooth. Fixed and movable fingers of chela with respectively 12 and13 oblique rows of granules on the male holotype and 12-14 on the female paratype. Trichobothriotaxy; orthobothriotaxy A-α (alpha) ( Vachon 1974, 1975). Legs: tarsus with two series of 6-7 setae on ventral surface.

Habitat.

The new species inhabits the tropical forests of the Ecuadorian Andean Mountains, in the Pichincha Province. The specimens were collected at an altitude of 2200 m, inside of rotten Lauraceae logs.