Chactas moreti, Lourenco, Wilson R., 2014

Lourenco, Wilson R., 2014, The second confirmed record of the scorpion genus Chactas Gervais, 1844 (Scorpiones, Chactidae) from Ecuador with description of a new species from the Amazonian Province of Sucumbios, ZooKeys 372, pp. 17-26 : 19-21

Chactas moreti sp. n. Figs 1-5, 7-9, 11-12, 14-17

Material examined.

Ecuador, Province of Sucumbíus, San Pablo de Kantesiya, near to the Aguarico River, 20/V/1985 (J.-M. Touzet & P. Moret). Rainforest, under rotten log.

Male holotype, one male and two female paratypes. Deposited in the Muséum national d’Histoire naturelle, Paris.

Etymology.

Specific name honours Dr. Pierre Moret Université de Toulouse - Le Mirail, who sends us the specimens and donated it to our collections.

Diagnosis.

Moderate in size with the male holotype being 43.1 mm in total length and 40.6 mm for the female paratype. Coloration blackish-brown, except for the venter which is reddish-yellow and legs which are reddish. Body and appendages very weakly granulated or smooth, with minute punctation. Pectines with 8 teeth in males and 8-9 in females. Trichobothrial pattern type C neobothriotaxic ‘majorante’. Chela with 4 ventral trichobothria; patella with 5 ventral and 17 external trichobothria. Sexual dimorphism strongly marked by distinct morphometric values (see measurements after description).

Relationships. The new species can be distinguished from others in the genus Chactas , and in particular from Chactas mahnerti Lourenço, 1995 which is distributed in Ecuadorian Andes, by the following features: (i) a generally darker coloration, blackish-brown, whereas Chactas mahnerti is overall reddish-yellow to reddish-brown, (ii) a smaller global size and quite distinct morphometric values - see measurements after the description, (iii) metasomal segments are very weakly granulated and vesicle totally smooth in the new species, (iv) anterior margin of male carapace is concave in the new species, whereas the male carapace of Chactas mahnerti is convex.

Description based on holotype and paratypes.

Coloration. Generally blackish-brown. Prosoma: carapace blackish-brown. Tergites blackish-brown, paler than the carapace and with a central longitudinal yellowish stripe. Metasomal segments blackish-brown, with blackish zones over carinae; vesicle reddish-brown. Chelicerae reddish-yellow to reddish-brown with diffused variegated brownish spots; fingers uniformly dense and blackish; some teeth are reddish. Pedipalps blackish-brown; femur blackish; patella blackish-brown, darker than chela; chela hand very dark reddish-brown; finger blackish. Legs reddish-yellow. Venter and sternites reddish with some yellowish zones; pectines and genital operculum yellow to reddish-yellow.

Morphology. Anterior margin of carapace with a weak to moderate concavity; lustrous and acarinate, with minute punctation behind median eyes; furrows shallow. Sternum pentagonal, wider than long. Tergites acarinate, smooth and shiny with punctations. Pectinal tooth count 8-8 (male holotype) 8-8 (male paratype), 8-8 and 9-9 (female paratypes), fulcra absent. Sternites smooth and shiny with punctations, VII acarinate; spiracles moderate in size and oval to round in shape. Metasomal segments with a lustrous tegument; dorsal carinae weak to moderate on all segments, but better marked in males; latero-dorsal carinae vestigial on segments I to III, absent on IV; other carinae absent; segment V with small spinoid granulations on distal half of ventral aspect; vesicle smooth and lustrous. Pedipalps: Femur with dorsal internal, dorsal external and ventral internal carinae moderately to strongly marked; ventral external carina absent; dorsal and ventral faces without granulations, smooth; internal face weakly granular. Patella smooth and lustrous; dorsal internal and ventral internal carinae moderate to weak; ventral external carinae weak to vestigial; other carinae absent. Chela lustrous; ventral median and dorsal internal carinae weak; other carinae vestigial or absent; internal face with a few weak granules, other faces smooth. Dentate margins on movable and fixed fingers with a median denticle row composed of 7-8 groups of granules. Chelicerae with the dentition typical of the family Chactidae (Vachon, 1963), and with intense setation ventrally. Trichobothriotaxy type C; neobothriotaxic ‘majorante’ ( Vachon 1974); chela with 4 ventral trichobothria; patella with 5 ventral and 17 external trichobothria. Ventral surface of tarsus in legs III and IV with a median series of small spines and 5-6 external and internal setae.

Morphometric values (in mm) of male holotype and female paratype. Total length (including telson) 43.1/40.6. Carapace: length 5.6/6.0; anterior width 3.8/4.2; posterior width 5.8/6.4. Mesosoma length 12.2/12.4. Metasomal segment I: length 2.5/2.3, width 2.8/3.0; II: length 2.8/2.5, width 2.5/2.5; III: length 3.3/2.6, width 2.4/2.4; IV: length 4.2/3.3, width 2.3/2.3; V: length 6.1/5.6, width 2.2/2.3, depth 1.9/1.9. Telson length 6.4/5.9. Vesicle: width 2.4/2.3, depth 2.0/1.8. Pedipalp length 25.2/21/4: femur length 6.8/5.3, width 1.8/1.9; patella length 6.8/5.3, width 1.9/2.2; chela length 11.6/10.8, width 2.9/3.4, depth 2.7/3.0; movable finger length 5.0/5.4.

Comparative morphometric values (in mm) of male holotype and female non-type of Chactas mahnerti . Total length (including telson) 51.9/45.4. Carapace: length 7.6/6.8; anterior width 5.0/4.4; posterior width 7.3/7.1. Mesosoma length 12.6/14.7. Metasomal segment I: length 3.3/2.5, width 4.0/2.9; II: length 3.4/2.7, width 3.4/2.7; III: length 4.0/3.1, width 3.4/2.6; IV: length 5.0/3.4, width 3.2/2.5; V: length 7.7/5.9, width 3.1/2.4, depth 2.8/2.1. Telson length 8.3/6.3. Vesicle: width 3.2/2.4, depth 2.8/2.2. Pedipalp length 35.8/24/1: femur length 9.8/6.1, width 2.3/2.3; patella length 10.1/6.2, width 2.3/2.6; chela length 15.9/11.8, width 3.2/3.6, depth 2.8/3.6; movable finger length 6.2/6.0.