Tityus atriventer Pocock, 1897

Teruel, Rolando & Kovařík, Frantíšek, 2011, Redescription and taxonomic position of Tityus atriventer Pocock, 1897 (Scorpiones: Buthidae), Euscorpius 115 (115), pp. 1-9 : 1-7

publication ID	https://doi.org/ 10.18590/euscorpius.2011.vol2011.iss115.1
persistent identifier	https://treatment.plazi.org/id/183787BD-D47E-765B-FC33-9100FC363011
treatment provided by	Carolina
scientific name	Tityus atriventer Pocock, 1897
status

Treatment

Tityus atriventer Pocock, 1897 View in CoL

Figs. 1–6 View Figure 1 View Figure 2 View Figure 3 View Figure 4 View Figure 5 View Figure 6 , Tab. 1

Tityus atriventer Pocock, 1897: 519–520 View in CoL ; Kraepelin, 1899: 75, 86; Mello-Leitão, 1931: 121, 141; Mello-Leitão, 1939: 58, 64, 72; Mello-Leitão, 1945: 299, 309; Waterman, 1950: 168; Armas, 1982: 6, tab. 2; Lourenço, 1984a: 354; Lourenço, 1984b: 101, 104; Armas, 1988: 73-74, 93.

Lourenço, 1988: 356; Kovařík, 1998: 119; Fet & Lowe, 2000: 230, 234; Lourenço, 2006: 60.

Diagnosis: species of very small size (males 28–32 mm, female 38 mm) for the genus. Body light yellowish brown, very densely spotted with blackish brown, tergites without well-defined dark stripes; metasomal segment V and telson not conspicuously darker; pedipalp fingers deeply infuscate. Pedipalp chela and metasomal segment V inflate in larger males, incrassate in smaller males and females. Sternite V with a large smooth patch in both sexes, larger and bulkier in males. Dorsolateral carinae of metasomal segments II-IV with distal tooth slightly enlarged, more so in smaller males. Telson vesicle smooth to vestigially granulose; subaculear tubercle large and conical, with two large dorsal granules. Pedipalp fixed finger with 13–14 principal rows of granules, movable finger with 14–15; basal lobe/notch combination strong in males, moderate in females. Pectines with 16–17 teeth in males, and 14–15 in females; basal middle lamella moderately dilated in both sexes.

Type data ( Fig. 1i View Figure 1 ): adult ♂ lectotype (32 mm long) and adult ♀ paralectotype (38 mm long), herein des- ignated ( BMNH: 1894.10.20.29–30): GRENADA, Balthazar ; 250–300 feet above sea level; March 4 th and 12 th; H. H. Smith. Note: both type-specimens were stored inside the same vial, together with three white labels which textually read ( Fig. 3e View Figure 3 ): 1) " Balthazar (Windward) 250 ft. March 4 Thicket near stream. Under bark of rotten log. " [handwritten by an unknown person]; 2) " Near Balthazar (Windward) 300 ft. March 12. Dry, shady hillside, under piles of rotting leaves. " [handwritten by the same person as the former]; 3) " 1894.10.20.29–30. Tityus atriventer Pocock. Balthazar (Windward) Grenada. 250' and 300'. March 4 th and March 12 th. Pres 'd. W. Indies Expl. Comm. coll. H. H. Smith. " [handwritten by Pocock in India ink]. The first two labels obviously refer to each type-specimen, but it is impossible to make a definite match; the third label suggests that Pocock received both specimens and their labels already mixed .

New Record: SAINT VINCENT AND THE GRENADINES, Parish of the Grenadines, Union Island, Chatham Bay Trail , 12°35.800 N 61°26.700 W, 31–234 m above sea level, under rocks, rotten logs and termite nests, in dry coastal forest, June 4–22, 2010, M. J. Rivera, E. Bentz, 1 adult ♂ (Sco-0471) GoogleMaps .

Distribution ( Fig. 5 View Figure 5 ): this species has been collected only twice at Grenada and Union, two of the southernmost islands of the Lesser Antilles (Windward Islands), which are separated by a 55 km distance. It probably occurs also in other intervening Grenadines such as Carriacou and Ronde.

Redescription (based upon the adult male lectotype, unless otherwise stated): Coloration ( Figs. 2–4 View Figure 2 View Figure 3 View Figure 4 : male from Union, both lectotype and paralectotype too faded for accurate description) basically light yellowish brown, very densely and irregularly spotted with blackishbrown all over the body and appendages including coxosternal region and sternites; tergites without well-defined dark stripes; metasomal segment V and telson of the same color as the remaining segments; chelicerae densely reticulated with blackish brown; pectines pale yellowish, moderately spotted with blackish brown. Pedipalps densely spotted with dark brown on both femur and patella; chela sparsely spotted over carinae, with fingers deeply infuscate. Carapace ( Fig. 1b View Figure 1 ) trapezoidal, without distinct carinae; anterior margin very widely Vshaped; tegument very finely and densely granulose, with many coarser granules scattered; median eyes separated by about one ocular diameter; three pairs of lateral eyes. Tergites ( Fig. 1b View Figure 1 ) with the same granular sculpture as on carapace; longitudinal carina strongly granulose; VII with two pairs of serrate lateral carinae. Chelicerae ( Fig. 1b View Figure 1 ) with typical dentition for the genus; tegument smooth and shiny. Pedipalps ( Figs. 1b–c, e View Figure 1 ) orthobothriotaxic A-α. Femur with all carinae coarsely granulose; intercarinal tegument very finely and densely granulose. Patella with all carinae coarsely granulose to costate; intercarinal tegument with the same granular sculpture as on femur, internal surface with conical to spiniform granules. Chela inflate, much wider than patella; hand with all carinae moderate, subgranulose to granulose, intercarinal tegument coriaceous; fingers with basal lobe/notch combination strong, fixed finger with 13/13 principal rows of granules, movable finger with 14/14, apical subrow composed by four granules aligned similar to principal rows. Legs ( Figs. 1b–c View Figure 1 ) with all carinae subserrate to granulose, intercarinal tegument finely and densely granulose. Sternum ( Figs. 1d View Figure 1 ) type 1, subpentagonal. Pectines ( Figs. 1c–d View Figure 1 ) somewhat small, with large fulcra; pectinal tooth count 17/16; basal middle lamella moderately dilated. Sternites ( Figs. 1c– d View Figure 1 ) very finely and densely granulose, with larger granules scattered, spiracles oval; posterior margin of sternite V with a large and smooth patch, which is light yellowish, subtriangular, wider than long and bulky; sternites VI–VII with two pairs of granulose lateral carinae. Metasoma ( Figs. 1a–d View Figure 1 ) slightly elongate but slightly enlarged distally, especially on V which is inflate but not globular; intercarinal tegument coriaceous to smooth, without coarse granules scattered; segments I–II with ten complete carinae, III–IV with eight, V with five, all moderately developed and granulose to subcrenulate; dorsolateral carinae on II–IV with the distal tooth only slightly enlarged; telson slightly elongate, vesicle oval and smooth to vestigially granulose, with a subgranulose ventromedian carina progressively elevated towards the subaculear tubercle, which is large, conical and equipped with two large dorsal granules; aculeus long, sharp and evenly curved.

Female (paralectotype, Figs. 1f–h View Figure 1 ): in general is similar to the male, but there is a strong sexual dimorphism evidenced by: (1) mesosoma relatively wider; (2) metasoma slightly less robust; (3) pedipalp chela oval and more slender; (4) pedipalp fingers with basal lobe/ notch combination less developed; (5) genital papillae absent; (6) pectines with teeth proportionally smaller; (6) sternite V with smooth patch slightly smaller and less bulky.

Variation: the two adult males clearly represent different size-classes. As correctly stated by Pocock (1897) in the original description of T. atriventer , the lectotype male and paralectotype female measure 32 mm and 38 mm, respectively, but the additional male from Union is a small adult which measures only about 28 mm ( Table 1).

This specimen also exhibits less marked sexual dimorphism: compared to the lectotype, it shows pedipalp chela and metasomal segment V less incrassate, pedipalp fingers with basal lobe/notch combination less developed (but still stronger than female paralectotype), and dorsolateral carinae of metasomal segments II–IV with the terminal granule largest and sharpest ( Figs. 1– 4 View Figure 1 View Figure 2 View Figure 3 View Figure 4 ). This progressive size-related gradation of the expression of such dimorphic characters has been already documented in other members of the " clathratus " species-group (Lourenço, 1983; Montoya & Armas, 2002; Rojas-Runjaic & Armas, 2007; Teruel & García, 2008).

Pectinal tooth counts varied as follows: male lectotype 17/16, male from Union 17/17, and female paralectotype 14/15. The number of principal rows of granules varied from 13–14 on fixed finger and 14-15 on movable finger.

Ecological notes: according to their label data, one of the types was collected under bark of rotten log in thicket vegetation near a stream, and the other was found among rotting leaves on a dry, shady hillside. The Union specimen was obtained in the soil of dry coastal forest, during a search under rocks, rotten logs and termite nests (Mel J. Rivera, pers. comm.). In both islands, T. atriventer lives in low-altitude, dry vegetation (thicket and coastal forest below 235 m above sea level; see Fig. 6 View Figure 6 ), syntopically with Tityus pictus smithii Pocock, 1893 .

Remarks: the very peculiar shape of the subaculear tubercle (sharp and conical, with its apex straight; see Figs. 1a View Figure 1 , 3f View Figure 3 ) makes very easy to separate T. atriventer from most other members of the " clathratus " group, which have the subaculear tubercle blunt and bladeshaped, with its apex distinctly curved towards the aculeus. The only other species of this group with a similar shape of the subaculear tubercle is Tityus columbianus (Thorell 1876) , but this species can be distinguished by its different color pattern (tergites with three irregularly defined dark stripes, metasomal segment V and telson conspicuously darkened to blackish), lower pectinal tooth count (12–15 in males, 12–13 in females), lower count of principal rows of granules on pedipalp fingers (12–13 on fixed finger, 12–14 on movable finger), metasoma with all carinae much more strongly developed (coarsely granulose to crenulate), and metasoma and telson with intercarinal spaces densely granulose and with many coarse granules scattered; in addition, T. columbianus is endemic to the high plateau (2200–3100 m a.s.l.) of mid Cordillera Central, in the Colombian Andes. For a complete and widely illustrated redescription of this species see Teruel & García (2008).

The present record of T. atriventer represents the rediscovery of this species after its original description, as well as its first finding outside Grenada. Also, the description of this small but adult male allows knowing more about the morphometric and morphologic variation of this taxon.