Vaejovis, C. L. Koch, 1836

A, Contreras-Félix Gerardo & Oscar, Francke B., 2019, Taxonomic revision of the “ mexicanus ” group of the genus Vaejovis C. L. Koch, 1836 (Scorpiones: Vaejovidae), Zootaxa 4596 (1), pp. 1-100 : 9-13

Vaejovis “ mexicanus ” group Soleglad, 1973

Diagnosis. This group of species can be differentiated by the following combination of characters (modified from Soleglad, 1973, Sissom, 1989, Santibáñez-López & Francke, 2010): a) three macro-setae on each side of the anterior margin of the carapace (Fig: 1-a); b) the reduction of the size of the posterior lateral eye almost to half the size of the anterior two eyes, and usually at 45 degrees of the middle eye to the inner portion of the carapace (Fig: 1-b), ocelli type 3B ( Loria & Prendini, 2014); c) carapace on males always shorter than metasomal segment V (Carapace/MS-V: average 0.92 ±0.05) except in V. nigrofemoratus ; on females this character is more variable (average 0.99 ±0.6); d) presence of two pairs of carinae on mesosomal tergite VII (Fig: 1-c); e) the partial fusion on the basal 2/3rds to 4/5ths of the female genital opercula; f) the presence of a pair of vestigial lateral carinae on mesosomal sternite VII (Fig: 1-d); g) the presence of 8 to 22 setae on sternite VII (the common pattern is 8 setae, which are always present (Fig: 1-d); h) the gradual weakening of metasomal lateral median carinae on posterior segments, obsolete in segment IV (Fig: 1-e); i) the lateral median carina of metasomal segment V never reaching the posterior edge, usually extending only on anterior half (Fig: 1-e); j) the laterobasal aculear serrations absent in adults (Fig: 1-f); k) pedipalp femur dorsal face flat, may present large granules on anterior face; l) femur always shorter than the carapace (Carapace L/Femur L x= 1.19 ±0.3 on males, x= 1.24 ±0.18 on females); m) pedipalp patella always longer than the femur (Femur L/Patella L x= 0.88 ±0.05 on males, x= 0.88 ±0.03 on females); n) the pedipalp femur height never greater than its width (Femur W/D x= 1.35 ±0.25 on males, x=1.35 ±0.12 on females); o) the stout, bulky pedipalp chela manus usually as wide as deep (CM W/D x=0.98±0.04 on males, x=0.98±0.06 on females); p) the presence of trichobothria ib - it at the base of the fixed finger (Fig: 2-a); q) on males, the fixed finger is never longer than the chela manus (CM L/FF L x= 1.28 ±0.24); r) pedipalp chela fixed finger with primary row of denticles divided into six subrows by five enlarged primary denticles, with six inner accessory denticles (Fig: 2-b); s) movable finger with primary row of denticles subdivided into six subrows by five enlarged primary granules and with seven inner accessory denticles; t) legs may present 2 to 6 telotarsal distal spinules (mode= 4) (The only exception being V. chiapas , because it presents only 1); u) telotarsi with 2 or more proinferior setae; v) telotarsi with 2-3 retroinferior setae; w) hemispermatophore lamelliform, with the capsular hooks always located basally (Fig: 2-c); x) hemispermatophore with median lobe present in capsular region, and never with a sclerotized mating plug (Fig: 2-e).

Differs from “ vorhiesi ” group as follows: Males of the “ vorhiesi ” group with a sclerotized mating plug in the hemispermatophore (Fig: 3-a), whereas males of the “ mexicanus ” group lack this structure. Adult members of the “ vorhiesi ” group present well-developed LAS (Fig: 3-b), and adults of the “ mexicanus ” group do not; presence on telotarsi of one seta only on the prointernal (pi) and retrointernal (ri) regions on the “ vorhiesi ” group, whereas the “ mexicanus ” group presents at least two or more setae on each side on legs III and IV; finally, the fixed finger of pedipalp chela is longer than the chela manus on the “ vorhiesi ” group, but on the “ mexicanus ” group the fixed finger is shorter than the chela manus, at least on males. It is important to indicate that there is at least one additional behavioral character to separate these two species groups: in the “ vorhiesi ” group the new-born first instar scorpions display a tile-like arrangement over the mother’s back (see photos in Ayrey 2013a, b; Ayrey & Webber, 2013), whereas on the “ mexicanus ” group the new-born first instars are randomly placed on the mother’s back.

The other species group within Vaejovis , “ Franckeus +nigrescens ” group, presents a morphology similar to the “ mexicanus ” group, but they differ as follows: the presence of a sclerotized mating plug, and the hook on the spermatophore elevated on the lamella in the “ Franckeus +nigrescens ” group (Fig: 3-c), but in the “ mexicanus ” group the sclerotized mating plug is always absent, and the lamellar hooks on the spermatophore are always located at the base near the capsular region. In addition, in the “ Franckeus +nigrescens ” group, the pedipalp chela manus is three or more times longer than wide (in almost every species more than four times longer than wide); whereas in the “ mexicanus ” group the chela manus is conspicuously rounded and always less than three times longer than wide (on males usually as long as wide); the tip on the pedipalp chela fingers presents a white, elongated patch at the tip (Fig: 3-d), plus the distalmost denticle conspicuously sharp and enlarged on the “ Franckeus +nigrescens ” group, but the members of the “ mexicanus ” group lack the white patch on the fingertips, and the distal denticle is rounded and not enlarged with respect to the other denticles. In addition, the metasomal ventral submedian carinae on segments I–IV are entirely smooth in most of the species of “ Franckeus +nigrescens ” group (except for V. norteno , V. dicipiens and V. carolinianus ) (Fig: 3-e), whereas in the “ mexicanus ” group these carinae are always granulose; and finally, adults of the “ Franckeus +nigrescens ” group always present LAS (Fig: 3-f), whereas in adults of the “ mexicanus ” group the LAS are absent. There are not many observations reported of females of the “ Franckeus +nigrescens” group carrying young on their backs, but on the few species of this group that have been observed and or photographed (unpublished data), the newborn are neatly stacked like tiles.

Type species: Vaejovis mexicanus C. L. Koch, 1836 , species group nominotype.

Species included (listed alphabetically): V. ceboruco sp. n.; V. chiapas Sissom, 1989 ; V. coalcoman Contreras- Félix & Francke, 2014; V. darwini Santibáñez-López & Francke, 2010 ; V. dugesi Pocock, 1902 ; V. dzahui Santibáñez-López & Francke, 2010 ; V. franckei Sissom, 1989 ; V. granulatus Pocock, 1898 ; V. maculosus, Sissom, 1989 ; V. mexicanus C. L. Koch, 1836 ; V. montanus Graham & Bryson, 2010 ; V. monticola Sissom, 1989 ; V. morelia Miranda-López, Ponce-Saavedra and Francke, 2012 ; V. nanchititla sp. n.; V. nigrofemoratus Hendrixson & Sissom, 2001 ; V. prendinii Santibáñez-López & Francke, 2010 ; V. pusillus Pocock, 1898 ; V. rossmani Sissom, 1989 ; V. santibagnezi sp. n.; V. setosus Sissom, 1989 ; V. smithi, Pocock, 1902 ; V. sprousei Sissom, 1990 ; V. talpa sp. n.; V. tapalpa sp. n.; V. tenamaztlei Contreras-Félix, Francke & Bryson, 2015 ; V. tesselatus Hendrixson & Sissom, 2001 ; V. trespicos Zarate-Galvez & Francke, 2009 ; V. zapoteca Santibáñez-López & Francke, 2010 .

Distribution. This group is endemic to the highlands of México, usually from 1800 to 2700 m (occasionally specimens can be found at lower elevations), the species are distributed from the northern part of the Sierra Madre Oriental (Nuevo Leon and Tamaulipas) south to the state of Chiapas; it is also present on the Sierra Madre Occidental, Mexican Trans-Volcanic Belt and the Sierra Madre del Sur (Fig: 4).

Natural history. These species are commonly found in temperate forest (oak, mixed oak-pine and pine forests) (Fig: 5-a, c), but some species are collected on more xeric habitats, such as V. maculosus , which occurs in desert scrub (Fig: 5-b, d). Almost all species in this group prefer humid microclimates, such as under the bark of fallen and rotting logs ( V. nigrofemoratus , V. talpa , V. santibagnezi , V. zapoteca ), but they can be found under rocks, and other objects that provide dark and humid spaces. Vaejovis mexicanus is common in Mexico City and often enters homes and gardens. On rare occasions, at night, some individuals can be found foraging on shrubs, rather than on the ground, where they commonly occur. The maternal care given to the new-born lasts for at least one month (laboratory observations, unpublished data).