Tityus forcipula species group

References after Fet & Lowe (2000: 230). Armas et al. (2002): 166 [in part]; Lourenço & Leguin (2008): 3; Teruel & García (2008): 1; Kovařík et al. (2013): 8 [in part]; Lourenço & Ythier (2013): 3; Brito & Borges (2015): 7, 8, 9, 14 [in part], fig. 4G; Flórez (2015): 85; Lourenço (2016): 7 [in part]; Miranda et al. (2020): 197, fig. 27.

Included species. Tityus crassicauda, Tityus cuellari, Tityus forcipula, Tityus fuhrmanni, and Tityus moralensis sp. nov.

Excluded species. Tityus dasyurus fulvipes, Tityus festae, Tityus florezi, Tityus jaimei, Tityus macrochirus, Tityus metuendus, and Tityus pachyurus are here transferred to the Tityus obscurus species group. Tityus dasyurus dasyurus is excluded from the Tityus forcipula species group, but not assigned to any species group, until additional morphological evidence is gathered.

Amended diagnosis. The Tityus forcipula species group is more similar to the Tityus bahiensis, Tityus trivittatus, and Tityus stigmurus species groups, and differs from Tityus androcottoides, Tityus bolivianus, Tityus clathratus, and Tityus obscurus species groups. The Tityus forcipula, Tityus bahiensis, Tityus trivittatus, and Tityus stigmurus species groups share ventral macrosetae of telotarsi I–IV distributed in two submedian rows (type II). Whereas, the Tityus androcottoides, Tityus bolivianus, Tityus clathratus, and Tityus obscurus species groups exhibit ventral setae of telotarsi I–IV irregularly distributed in a tuft (type I).

On the other hand, the Tityus forcipula species group differs from the Tityus bahiensis, Tityus stigmurus and Tityus trivittatus species groups in the following character state combination: i) pectines strongly sclerotized and brown colored (Figures 2B, D, 3B, D, 9A–D); ii) basal middle lamellae of female pectines dilated and suboval shaped or ovoid (Figures 2D, 3D, 9B, D); iii) female pectinal basal piece without glandular region; iv) ventral macrosetae of telotarsi I–IV strongly sclerotized and stout; v) metasomal segments (moderately or strongly) widening towards segment V (Figures 12A–D, 13A–D) (except in Tityus fuhrmanni that exhibit a conspicuous thinning towards segment V); and vi) subaculear tubercle small to medium and coarse with a small gap between the dorsal margin of the subaculear tubercle and the base of the aculeus (Figure 15A–D). Whereas, Tityus bahiensis, Tityus stigmurus and Tityus trivittatus species groups present i) pectines moderately sclerotized and white colored; ii) basal middle lamellae of female pectines not dilated; iii) female pectinal basal piece with a moderate to large glandular region; iv) ventral setae of telotarsi I–IV moderately sclerotized and fine; v) metasomal segments of similar wide or with an inconspicuous widening towards segment V, and vi) subaculear tubercle small and acute with a moderate gap between the dorsal margin of the subaculear tubercle and the base of the aculeus.

Taxonomic remarks. The Tityus forcipula species group was previously merged with the Tityus obscurus species group (previously referred as T. asthenes, see Lourenço et al. (2019)). However, based on a unique combination of phenotypic characters here is revalidated and separated from the Tityus obscurus species group. In order to set the boundaries of the Tityus forcipula species group we examined all the species that belong to this group, but Tityus crassicauda and T. dasyurus dasyurus.

In our morphological survey, we found that Tityus dasyurus fulvipes, Tityus festae, Tityus florezi, Tityus jaimei, Tityus macrochirus, Tityus metuendus, and Tityus pachyurus, exhibit ventral setae of telotarsi I–IV irregularly distributed in a tuft (type I). This character state together with the presence of pectines moderately sclerotized and white colored and basal middle lamellae of female pectines dilated and subcircular, exclude these taxa from the Tityus forcipula species group and locate them into the Tityus obscurus species group. Other characters such as a metasoma progressively widening towards segment V (club-like shaped metasoma) are shared by Tityus jaimei, T. metuendus, and T. pachyurus, as well as, species belonging to the Tityus forcipula species group. However, this character by itself is not enough to assign species to a given species group and must be used in combination with other characters with strong phylogenetic signal (e.g., Moreno-González et al. 2021).

Lourenço & Ythier (2013) described Tityus crassicauda and mentioned that it is closely related to T. forcipula. Their description has a detailed enough description that allows us to identify most of the character states of the Tityus forcipula species group. For example, the authors described the presence of two ventrosubmedian rows in the telotarsi (type II), the metasoma widening towards segment V and the dilation and oval shape of the basal middle lamellae of female pectines. Also, they provided colorful habitus pictures of both sexes that clearly show the strongly sclerotized pectines and the absence of glandular regions in the pectinal basal piece of the female. The situation of Tityus dasyurus is, however, diametrically opposite.

Pocock (1897) described Tityus dasyurus based on a single female from “ Porto Rico ”. Nevertheless, some authors argued it corresponds to a mislabelling error and this female most probably comes from a locality in Central or South America (Armas 2020). Santiago-Blay (1985) examined and redescribed the female holotype of T. dasyurus dasyurus. In this description, we observed that the morphology of the subaculear tubercle and the basal middle lamellae shape are very different from other members of the Tityus forcipula species group. The subaculear tubercle is conical, small and acute and presents a moderate gap between the dorsal margin of the subaculear tubercle and the base of the aculeus (Santiago-Blay 1985: fig. 13), whereas the basal middle lamellae is dilated and subcircular shaped (Santiago-Blay 1985: fig. 10). Both characters are very common among the Tityus androcottoides and Tityus obscurus species group members. However, the examination of additional morphological characters is needed to confirm the species group membership of this enigmatic species.

Finally, Tityus fuhrmanni is particularly interesting. This species was assigned to an independent species group by Mello-Leitão (1945) given the particular morphology of its metasoma, which exhibits a conspicuous and progressive thinning towards segment V, but also presents a remarkable development of the DSM on the metasomal segment III. We also noted that the males of T. fuhrmanni do not exhibit a bulkier chela compared to female chela, both male and female chelae ratios are somewhat similar. In this contribution, we temporarily followed the Lourenço (1984) designation of T. fuhrmanni in the T. forcipula species group. This species shares some character states with this species group such as i) telotarsi macrosetae stout and distributed in two ventrosubmedian rows (type II), ii) sclerotized pectines brown colored, iii) basal middle lamellae dilated and soboval/ovoid shaped in the female pectines, and iv) absence of glandular regions in the basal pectinal piece of the female pectine. However, additional studies and samples are required for testing the membership of this species into the Tityus forcipula species group.