Centruroides ixil, Trujillo & de Armas, 2016

Trujillo, Rony E. & de Armas, Luis F., 2016, A new species of Centruroides (Scorpiones: Buthidae) from Quiché, northwestern Guatemala, Euscorpius 233, pp. 1-8 : 1-7

Centruroides ixil sp. n.

Fig. 1 A–C, 2 A–G, 3 A–G, 4, Table 1 http://zoobank.org/urn:lsid:zoobank.org:act:1C2CB6

B8-46EA-45C3-BA07-D446D0D93F95

Type data. Male holotype, female paratype (MHN), Sotzil Village (15.61775 N, - 91.09745 W; 1173 m a. s.l.), Chajul Municipality, Quiché Department, Guatemala, September 2, 2016, Luis A. Trujillo, at night, UV light .

Distribution. Only known from the type locality ( Fig. 1 A).

Etymology. The specific name is a noun in apposition, designating the predominant Mayan ethnic group in the region where this new species lives.

Diagnosis. Male 68.5 mm in total length; female 56.6 mm. Base color light brownish; darker on last metasomal segments and posterior margin of tergites I– VI; cheliceral manus with dark brown reticulations all over; pedipalp chelae with light yellowish manus and blackish fingers; sternites III– VI brown yellowish in the male (darker on the female). Carapace finely granular, with moderate granules on the interocular triangle; anteromedian notch V-shaped. Pedipalp manus slightly wider (♂, Fig. 2 B) or slender (♀, Fig. 3 D) than patella; movable finger with moderately developed basal lobe. Pectines with 19 (♀, Fig. 3 E) or 20 (♂, Fig. 2 E) teeth; basal plate rectangular, wider than long. Metasoma: segments I–IV with dorsolateral carinae, lateral supramedian carinae, ventrolateral carinae and ventral submedian carinae moderately developed, granular to slightly serrate; segments II–IV with two pairs of ventrolateral macrochaetae; intercarinal spaces I–IV coriaceous; vesicle deeper than wide; subaculear tubercle strong, spine-like, with tip pointing towards the apex of the aculeus. Metasomal segment III length/width ratio: ♀ = 1.86, ♂ = 2.76; metasomal segment V: length/width ratio: ♀ = 2.43, ♂ = 2.78; carapace length/metasomal segment V length ratio: ♀ = 0.88, ♂ = 0.68.

Description of the male holotype ( Fig. 1 B–C, 2 A– F). Base color light brown. Carapace with posterior margins infuscate and distinct dusky marbling throughout ( Fig. 2 A); interocular triangle darker. Tergites I–VI with dusky band along posterior margins ( Fig. 1 B). Metasomal segments I–IV light brown; V and telson slightly darker. Cheliceral manus with dark brown reticulations all over ( Fig. 2 B). Pedipalp femur and patella brownish, with small yellowish areas around the trichobothria; manus light yellowish, with blackish fingers. Legs yellowish with pale brown marks. Sternites III–VI brown yellowish; VII darker.

Carapace ( Fig. 2 A) 1.03 times longer than wide; anteromedian notch V-shaped, reaching the posterior margin level of the second pair of lateral eyes; interocular triangle with moderate granules, the rest finely and sparsely granular. Anterior median carinae vestigial, with disperse moderate granules; superciliary carinae strong, subgranulose; posterior median carinae moderate, subgranulose, other carinae indistinct.

Pedipalps orthobothriotaxic Type A. Femur ( Fig. 2 B): internal surface with large granules, all other surfaces finely granular; dorsointernal, dorsoexternal and ventrointernal carinae moderate, granular; ventroexternal carina strong, serrate. Patella ( Fig. 2 B): internal surface with 5–6 large conical granules; dorsal, external and ventral surfaces finely granular; dorsointernal and dorsoexternal carinae moderate, granular; dorsomedian carina weak, granular; ventrointernal carina weak, granular. Manus ( Fig. 2 B, D): globose, 1.32 times wider than patella; intercarinal surfaces almost smooth, dorsomarginal, dorsal secondary and digital carinae weak to moderate, minutely granular to subgranular; ventroexternal carina strong, smooth; other carinae vestigial. Fixed fingers with eight oblique rows of denticles; trichobothrium et basal to db. Movable fingers with eight principal oblique rows of denticles, plus a distal short one with four denticles.

Pectines ( Fig. 2 E) with 20/20 teeth; basal plate rectangular in shape, 2.14 times wider than long.

Mesosoma. Tergites I–VII finely granular, with some larger granules on the posterior one-half of I–VI ( Fig. 2 C); longitudinal median carina I–VII moderate, subgranular. Tergite VII lateral and submedian carinae moderate, granulose. Sternites III–VI mostly smooth, except on lateral submargins; VII mostly smooth, with lateral and submedian carinae moderate to feeble, subgranular.

Metasoma ( Fig. 2 F). Intercarinal spaces I–IV coriaceous, with sparse minute granules. Segments II–IV with two pairs of ventrolateral macrochaetae. Segment I, ten carinae; II–IV, eight carinae; V with five carinae; on II, the lateral inframedian carina is only represented by 6–8 distal granules, being the distal ones the largest; I–IV with dorsolateral, lateral supramedian, ventrolateral and ventrosubmedian carinae moderately developed, granular to slightly serrate; dorsolateral carinae with a larger terminal granule. Segment V: intercarinal spaces finely granulate; dorsolateral, ventrolateral and ventromedian carinae moderate, granular. Vesicle with ventral and lateral surfaces finely granular, 1.08 times as wide as deep; subaculear tubercle strong, spine-like, with tip pointing towards the apex of the aculeus ( Fig. 2 F, G).

Legs with femora finely granular on the prolateral surface. Telotarsi moderately covered by fine setae on the ventral surface.

Female ( Fig. 3 A–G). The only examined female differs from the male holotype by having a darker pattern, mainly on carapace and tergites ( Fig. 3 A–B), small size ( Table 1), carapace ( Fig. 3 C) and tergites most strongly granulate, pedipalp chelae with slender manus ( Fig. 3 A, D), pectines with 19/19 teeth ( Fig. 3 E), metasoma not attenuate (segment III length/width ratio = 1.86 vs 2.76; segment V length/width ratio = 0.88 vs 0.68; carapace length/metasomal segment V length ratio = 2.43 vs 2.78).

Comparisons

The male holotype of this new species resembles that of C. caral Armas et Trujillo, 2013 , from which it differs by having a most globose pedipalp manus, telson wider than its height, and more attenuate metasoma (length/width ratio: segments II–IV = 2.4, 2.7 and 1.4, respectively; 1.7, 2.2 and 2.5 in the male holotype of C. caral , only known specimen of this taxon). Also, general pattern differs in both species: base color light brownish in C. ixil , but light yellow in C. caral ; each tergite bearing a narrow yellow median longitudinal line in C. caral , but absent in C. ixil .

Although male scorpions of the same species that reach the adulthood from different stadia show significant morphometric differences, those observed between the respective males of C. caral and C. ixil seem to be not caused by that phenomenon. Unfortunately, the female of the former is unknown, but the differences between the males of these two species strongly suggest that C. ixil is not the large male of C. caral .

Natural History

The holotype male and paratype female were collected on a rocky wall partly covered by vegetation in a mountainous subtropical wet forest, 1173 m a.s.l., a few kilometers west from Visís Cabá Biosphere Reserve. The male and female were separate 30 cm to each other, about 3 m over the soil, in a place covered by leaf litter. The type locality is in the margin of a nonpavement road, approximately at 300 m from a small river cascade ( Fig. 4).

In Guatemala, the mountainous subtropical wet forest is located in parts of Los Cuchumatanes, Chamá, Chuacús and Las Minas mountain systems. This forest is characterized by a complex vegetation structure over an irregular landscape, with high levels of humidity and precipitation and a great diversity of habitats, supporting high levels of endemism ( Castañeda, 2008). This ecosystem is sometimes known as “mix forest” due to the association of conifers and broad-leaf species. Epiphytes, mosses and ferns are also abundant in this type of forest.

Biogeographic Comments

The type locality of C. ixil belongs to Sierra de los Cuchumatanes, a continuous of the Chiapas Range. According with several authors (for details see Morrone, 2001), this orographic area belongs to the Chiapas province, a biogeographic unity that shows a strong relationship with the neighboring province of Eastern Central America. To the later belongs the type locality of C. caral , a species geographically and ecologically disjointed from C. ixil by the valleys of Motagua and Chixoy, two areas with xeromorphic vegetation. A similar distribution is shown by the beetles Crysina purulensis (Monzón et Warner, 1993), C. diversa (Ohaus, 1912) , C. quiche (Moran, 1990) , and C. rodriguezi (Boucard, 1878) , all them restricted to Cuchumatanes Range, whereas C. strasseni (Ohaus, 1924) and C. ericsmithi (Monzón et Cano, 1999) are endemic from Merendón Range ( Monzón Sierra, 2006).

On this respect, C. ixil and C. caral seems to be closely related species, perhaps originated as result of a vicariance event during the Upper Pliocene, and pronounced during the last two millions of years, when the valleys of Motagua and Chixoy became xeric ecosystems.