Rhopalurus cf. laticauda Thorell, 1876

Teruel, Rolando & Cozijn, Michiel A. C., 2013, On the distribution of the genus Rhopalurus Thorell, 1876 (Scorpiones: Buthidae) in the southern Caribbean islands, Euscorpius 179, pp. 1-7 : 2-5

Rhopalurus cf. laticauda Thorell, 1876

Figures 1–4, Tables 1–2

Records: VENEZUELA, Dependencias Federales, Isla La Tortuga, southwest part, 1 August 1936, leg. P. Wagenaar Hummelinck, 1♀ (NBC-433). Archipiélago de Los Hermanos, Isla Pico [= Morro Pando], 20 August 1936, leg. P. Wagenaar Hummelinck, 1 juvenile (NBC- 431). Archipiélago de Los Frailes , Isla La Peche , 19 June 1936, leg. P. Wagenaar Hummelinck, 2 juveniles (NBC-426). Archipiélago de Los Testigos , Isla Conejo, inside cave, 17 June 1936, leg. P. Wagenaar Hummelinck, 1 juvenile (NBC-430). Angoletta, 15 June 1936, leg. P. Wagenaar Hummelinck, 2♂♂ (NBC-434) . Estado de Nueva Esparta, Isla Margarita, Porlamar, Punta Mosquito , 4 June 1936, leg. P. Wagenaar Hummelinck, 1 juvenile (NBC-428). October 2007, local collector, 3♂♂, 4♀♀ ( RTO: Sco-0386), 2♂♂, 2♀♀, 2 juveniles ( MCCL). Isla Coche, El Guamache, 25 June 1936, leg. P. Wagenaar Hummelinck, 1♂, 1 juvenile (NBC-435). Isla Cubagua, 21 May 1936, leg. P. Wagenaar Hummelinck, 1 juvenile (NBC-424) .

In addition, the Wagenaar Hummelinck collection deposited at the NBC contains the following other specimens of Rhopalurus :

 Rhopalurus cf. laticauda : VENEZUELA, Falcón, Península de Paraguaná, Carirubana, Quebrada de la Compañía , 15 February 1937, leg. P. Wagenaar Hummelinck, 1 juvenile (NBC-429). Cerro Transverso, 16 February 1937, leg. P. Wagenaar Hummelinck, 3 juveniles (NBC-427) .

 Rhopalurus caribensis : COLOMBIA, La Guajira, south of Cabo de la Vela, El Cardón , 22 January 1937, leg. P. Wagenaar Hummelinck, 1 juvenile (NBC-436) .

Ecological Notes: individuals captured in 2007 at Isla Margarita were kept for several years by the second author (MC), under standard laboratory conditions for such a xerophilic scorpion. Females became adult always at instar six (i.e., after the fourth nymphal instar) and males reached adulthood at instar five or rarely six, but wild-caught specimens examined herein indicate that also females can mature at instar five. Gestation lasts for about six months, and the single female that gave birth in captivity (the largest measured in Table 2), produced a litter of 26 pulli and died shortly after delivery. Captive raised individuals lived for around three years in captivity.

Comments: all specimens are well preserved in alcohol and most are in good condition; only two specimens are damaged, evidently because of bad handling while collecting (i.e., both were clearly crushed when still alive). The labels inside the vials were produced on a typewriter and are in good condition too; all bear the collection locality and the date of collection. In some specimens the natural coloration pattern has faded due to the long (76–77 years) preservation in ethanol. The glass containers and vials where filled with fresh 70% ethanol after examination of the scorpions. The vials 425 and 432 were not present in the jar; at this moment it is unclear if both are actually missing or misplaced somewhere else in the collection.

The new records herein documented for Rhopalurus laticauda sensu lato, greatly increase its known distribution in the insular territories of northern South America; nevertheless, the precise identity of these insular populations could not be satisfactorily established. The main morphological characters such as color pattern (somewhat darker overall, with deep blackish metasomal segment V and telson), very robust pedipalps and metasoma, high pectinal tooth counts, and tegumentary sculpture (coarsely and densely granulose), all clearly indicate that they are not referable to Rhopalurus caribensis Teruel et Roncallo, 2008 , but generally match instead the mainland taxon that has traditionally been referred to as R. laticauda . But as already noted elsewhere, the status of these northern Venezuelan populations of the genus still needs to be clarified (Teruel & Roncallo, 2008; Rojas-Runjaic & Becerra, 2008). For this reason, we referred here to these insular specimens as " Rhopalurus cf. laticauda " or " Rhopalurus laticauda sensu lato ", to indicate that it is both the closest match and a tentative identification only.

Very interestingly, Manzanilla & Sousa (2003) stated that the single specimen they examined from Archipiélago de Los Roques was not conspecific with the remaining populations they identified as to R. laticauda , including a good sample from Isla Margarita. Taking into account that R. caribensis was described from nearby Colombia and recorded from Venezuela only five years later (Teruel & Roncallo, 2008; Rojas- Runjaic & Becerra, 2008), and thus, it was unknown to Manzanilla & Sousa (2003), it is necessary to study additional specimens from Los Roques (which are located farther west than the localities recorded herein) to clarify the specific identity of this yet another insular population.

The specimens herein studied confirmed that the differences previously recorded by Teruel & Roncallo (2008, 2010) in pectinal tooth count between R. caribensis and R. laticauda sensu lato, although slight, still remain diagnostic. The single juvenile female of the former has 21/20 pectinal teeth, whilst among the whole sample of the latter the counts per pectines were as follows: males, 23 (9), 24 (14), 25 (3); females, 21 (10), 22 (10), 23 (4).

Another female from Isla Margarita (RTO: Sco- 0386) has a tooth count of 20/19, but it was excluded from the range given above because it clearly represents an anomaly ( Fig. 4): in each pecten, the basalmost tooth is greatly enlarged and actually seems to represent a fusion of at least two teeth; both pectines are strikingly symmetrical, which is the first documented case. According to our personal observations, fused teeth are very common among scorpions, but almost always are restricted to one pectine only; the very few double cases we have found have always been asymmetrical, because different numbers and positions of teeth are involved.