Troglotayosicidae (Fet & Sissom, 2000)

Soleglad, Michael E. & Fet, Victor, 2003, High-level systematics and phylogeny of the extant scorpions (Scorpiones: Orthosterni), Euscorpius 2003 (11), pp. 1-175 : 85-87

" Troglotayosicidae " = Troglotayosicus + Belisarius

Constrained topology analysis

We present here the results of our investigation into the overall reduction in support when certain original taxonomic topologies are imposed on our current data set. In particular, we are interested in the support differences involving chactid genera Anuroctonus and Uroctonus , and the family Troglotayosicidae (synonymized in this study). We examine the effects of these topology changes of Anuroctonus and Uroctonus , both when considered separately, and when considered together, since they are now included in the subfamily Uroctoninae . For Troglotayosicidae , we test several topological arrangements within the chactoids, involving families Euscorpiidae , Chactidae , and Superstitionidae . Fig. 117 shows partial cladograms illustrating these constrained topologies.

Anuroctonus . Stockwell (1992) placed genus Anuroctonus in family Iuridae , subfamily Caraboctoninae (in this study superfamily Iuroidea , family Caraboctonidae ) as the sister genus to Hadrurus . Our results place Anuroctonus in family Chactidae , subfamily Uroctoninae . We constrained our current topology by moving Anuroctonus from Uroctoninae to superfamily Iuroidea , binding with Hadrurus in family Caraboctonidae ( Fig. 117). The number of tree steps increased by 59, an increase in steps of 13.7%; the CI, RI, and G-Fit character support decreased 2.8–12.1% (see Table 8). This result exhibits a significant reduction in support, especially considering it only involved the movement of one taxon out of a group of 60. Of course, much of this reduction is caused by the somewhat basal placement of Iuroidea , shown in this present study to be the most primitive superfamily of the parvorder Iurida .

Uroctonus . Stockwell (1989: Fig. 257), in his cladistic analysis, considered Pseudouroctonus , Uroctonus , and Uroctonites as a well defined clade within Vaejovidae . This is the only cladistic treatment, to date, of this small assemblage of genera. In our present study, it is shown that Uroctonus is a member of the family Chactidae . We constrained our current topology by moving Uroctonus to family Vaejovidae , and coupling it with Pseudouroctonus ( Fig. 117). The resulting increase in tree steps is 30, a 7% reduction in tree support, and the CI, RI, and G-Fit character support decreased 1.4– 6.5% ( Table 8). This decrease in overall support is considerably less than that seen in the constrained topology for Anuroctonus . This is easily explained however, since the movement of Uroctonus to Vaejovidae involves the same superfamily, Chactoidea , whereas Anuroctonus was moved across considerable “phylogenetic distance” to Iuroidea .

Anuroctonus and Uroctonus . Since newly created subfamily Uroctoninae includes both (and only) Uroctonus and Anuroctonus , we also tested the differences in support when both topological constraints discussed above are combined. This resulted in an increase of 80 tree steps, a 18.6% decrease in tree support. The CI, RI, and G-Step ranged 3.8–15.7% reduction in character support.

Troglotayosicidae . The family Troglotayosicidae , recently created by Lourenço (1998a), includes two genera, Troglotayosicus and Belisarius . Previously, cladistic results of Stockwell (1989, 1992) placed both of these genera in family Superstitioniidae . In a recent cladistic revision of family Euscorpiidae (Soleglad & Sissom, 2001) , it was demonstrated that Belisarius showed a close affinity to the South American chactids. Both of these genera were treated in our current study, which demonstrates that Belisarius is a member of Chactidae , as suggested by Soleglad & Sissom (2001), subfamily Brotheinae , and Troglotayosicus is a member of family Superstitioniidae , showing a close affinity to the North American genus Superstitionia , as originally determined by Stockwell (1989, 1992). Based on all of these analyses, we tested four constrained topologies for the original family Troglotayosicidae , combining it with different chactoid families ( Fig. 117). Only family Vaejovidae was excluded. As can be seen in Table 8 the reduction in support was minimal, increase in steps ranged 15–20 (3.5–4.7%) and character support decreased 0.7–4.5%. The topology combining Troglotayosicidae with Chactidae exhibited the less reduction in support, and the joining of Troglotayosicidae with Euscorpiidae showed the most reduction. This low reduction in support is not surprising since the relocation of the two genera involved clades that are phylogenetically close.

Classification of the Orthostern Scorpions

Below, we list the proposed classification of all above-genus taxa (parvorder, superfamily, family, subfamily, tribe, and subtribe), which we recognize among orthostern scorpions, with brief taxonomic history of each taxon. Full list of extant genera included under each taxon can be found in Table 9. Details on taxonomy, species composition, and geographic distribution of most scorpion genera can be found in Fet et al. (2000).

Our treatment of the entire taxonomic diversity of scorpions compels us to approach the family-group ranks with a degree of balance and proportionality. Thus, while we accept topology of Prendini (2000), we downgrade three of his families in Scorpionoidea ( Diplocentridae , Hemiscorpiidae , and Heteroscorpionidae ) to subfamily rank (under, respectively, Scorpionidae , Liochelidae , and Urodacidae ). At the same time, in an opposite move, we elevate Caraboctoninae to the family rank in Iuroidea . These taxonomic acts, in our opinion, are justified by the required proportionality of cladistically defined family-level distinctions. While family-group ranks are somewhat arbitrary, the taxonomic balance within superfamilies Iuroidea , Chactoidea , and Scorpionoidea is best achieved by assigning family level only to primary clades (two in Iuroidea , four in Chactoidea , and four in Scorpionoidea ). From our viewpoint, retaining Hemiscorpiidae , Heteroscorpionidae , or even a traditional Diplocentridae as families would create an unnecessary emphasis on family diversity of Scorpionoidea —in fact, subfamilies in Chactoidea (i.e. Chactinae and Brotheinae ) present deeper evolutionary differences than, say, those between Scorpioninae and Diplocentrinae . Since Prendini (2000) addressed almost exclusively scorpionoid taxa (his outgroups included only a Centruroides and a Chaerilus ), his assignment of family or subfamily ranks was inevitably biased toward Scorpionoidea . It is not the “splitting” or “lumping” but the proportionality issue which is important here. Indeed, the same type of a perspective bias led Kjellesvig-Waering (1986) to suggest lumping all extant scorpions into three families; or led Lamoral(1980) to suggest that Chactidae and Vaejovidae should be lumped into one family; or prevented, for many decades, a well-deserved recognition of Iuridae family rank.

Order Scorpiones C. L. Koch, 1837 Suborder Neoscorpiones Thorell & Lindström, 1885 Infraorder Orthosterni Pocock, 1911

This infraorder, as suggested by Stockwell (1989), included all Recent scorpion families as well as the Tertiary genus Mioscorpio and the Carboniferous family Palaeopisthacanthidae . Stockwell (1989) did not discuss the Cretaceous genus Araripescorpius (Campos, 1986) and Tertiary genera Sinoscorpius and Uintascorpio (Hong, 1983; Perry, 1985), probably due to a very fragmentary nature of these fossils. A number of additional fossil orthostern taxa have been described or recorded since 1989, both within Recent families (Lourenço & Weitschat, 1996, 2000, 2001; Santiago-Blay & Craig, 1998; Santiago-Blay et al., 2001) and outside of them (Jeram, 1994a, 1994b; Carvalho & Lourenço, 2001; Lourenço, 2001c, 2002a, 2003; Santiago-Blay et al., in press).

To accommodate all Recent families, we establish four parvorders (the order-group taxonomic category subordinate to infraorder): Pseudochactida , Buthida , Chaerilida , and Iurida . Some extinct species, genera, and families are also included under these four parvorders as specified below.

Diversity content of extant taxa in four parvorders is unequal. Parvorders Pseudochactida and Chaerilida each include a single monotypic family; parvorder Buthida includes two families and 82 genera; and parvorder Iurida includes 10 families and 83 genera ( Table 9). Phylogenetic relationship between four extant parvorders as established in our analysis is a “ladderized” phylogeny ( Pseudochactida , ( Buthida , ( Chaerilida , ( Iurida ))) ( Fig. 114).

Characters used to distinguish the four parvorders of Recent scorpions are the fundamental orthobothriotaxic pattern types, setal and spinule armament of the leg tarsus, fundamental sternum types, cheliceral dentition, and basic hemispermatophore types.