Typhlochactas sylvestris Mitchell and Peck,

Vignoli, Valerio & Prendini, Lorenzo, 2009, Systematic Revision Of The Troglomorphic North American Scorpion Family Typhlochactidae (Scorpiones: Chactoidea), Bulletin of the American Museum of Natural History 2009 (326), pp. 1-94 : 5-10

Typhlochactas sylvestris Mitchell and Peck,

1977, the fourth species to be described in

TABLE 2 List of Typhlochactidae Mitchell, 1971 species, authorities, Mexican states, municipalities, localities of occurrence, habitat, specimens and depositories Abbreviations as follows: OAX 5 Oaxaca ; QRO 5 Queretaro; SLP 5 San Luis Potosí; TAM 5 Tamaulipas ; VER 5 Veracruz this group of scorpions, was collected with Berlese from montane forest litter, 25 km S of Valle Nacional, Oaxaca, unlike the first three species, collected from deep inside caves. At this point in the taxonomic history of these scorpions, Mitchell & Peck (1977: 164) noted :

No diagnosis of the genus Typhlochactas … can be entirely satisfactory. Each species presents its own unique features, features of considerable importance in scorpion taxonomy …. Thus, it seems at present that there are but two reasonable alternatives, maintain a single genus—perhaps one so heterogeneous as to be artificial, or separate each species into its own genus.

A monotypic genus, Alacran Francke, 1982 , was subsequently created to accommodate Alacran tartarus Francke, 1982 , a large troglobite collected in four deep caves in the Sistema Huautla, Oaxaca, and which differed from the other four species in many important characters. In spite of the differences between Alacran and Typhlochactas, Francke (1982a) recognized a close phylogenetic relationship between the two genera, while following Mitchell (1968) in discounting a close relationship between them and Belisarius xambeui Simon, 1879 , a troglomorphic endogean species from the Pyrenees of France and Spain and, at the time, the only other eyeless scorpion known. Francke (1982a: 57) postulated that the three characters ignored by Mitchell (1968: 770, 771) are synapomorphic for Alacran and Typhlochactas , and proposed that the two genera are closely related to Superstitionia donensis Stahnke 1940 , an epigean scorpion from the southwestern United States and Mexico ( Stahnke, 1940; Williams, 1980), placed at the time in a monotypic subfamily, Superstitioniinae Stahnke, 1940 (as Superstitioninae), of Chactidae . Francke (1982a) downgraded Typhlochactinae to a tribe, Typhlochactini Mitchell, 1971, of Superstitioniinae, included A. tartarus in Typhlochactini, and placed Superstitionia in tribe Superstitionini Stahnke, 1940 . Reluctant to recognize Chactidae as defined at the time, Francke (1982a) placed Superstitioniinae incertae sedis in superfamily Chactoidea Pocock, 1893 (a putatively monophyletic group comprising Chactidae Laurie, 1896 , Iuridae Thorell, 1876 , and Vaejovidae Thorell, 1876 ). Francke (1986) continued to recognize Superstitioniinae as incertae sedis in Chactoidea although Francke (1985) listed it as a subfamily of Chactidae .

Typhlochactas cavicola Francke, 1986 , collected in Cueva del Vandalismo, Tamaulipas, was the sixth species in the group to be described. In light of the discoveries of Alacran , T. cavicola and T. sylvestris, Francke (1986) reassessed generic limits within the group. Francke (1986: 5) recognized the important differences between T. elliotti and the other species of Typhlochactas noted earlier by Mitchell (1971: 145), and created a monotypic genus, Sotanochactas Francke, 1986 , to accommodate it:

These species [ Alacran , T. cavicola and T.

sylvestris] … have indeed assisted in clarifying the systematic relationships within the tribe

Typhlochactini Mitchell. Typhlochactas rhodesi

Mitchell, Typhlochactas reddelli Mitchell , T.

sylvestris and T. cavicola form a compact monophyletic group of species, and the differences between this group and Typhlochactas elliotti Mitchell are such that the recognition of a new genus is now justified.

Typhlochactas mitchelli Sissom, 1988 , the fifth species of Typhlochactas to be described, was the second in the genus to be collected from montane forest litter. This species was collected on Cerro Ocote, Oaxaca, in the same mountain range as the type locality of T. sylvestris . Unlike the holotype of T. sylvestris , collected with Berlese ( Mitchell and Peck, 1977), the holotype and paratypes of T. mitchelli were taken from under stones buried deep in litter (A.G. Grubbs, personal commun.).

Sissom (1988, 1990) and Beutelspacher Baigts (2000) followed Francke (1985) in recognizing Superstitioniinae as a subfamily of Chactidae and Typhlochactini as a tribe of Superstitioniinae. Stockwell (1992) meanwhile elevated Superstitioniinae to family rank for the first time, and included within it Belisarius xambeui and another troglomorphic taxon, Troglotayosicus vachoni Lourenço, 1981 , from Los Tayos Cave, Ecuador, at the time both placed in Chactidae , based on results of an unpublished cladistic analysis of scorpion higher phylogeny ( Stockwell, 1989).

Typhlochactas granulosus Sissom and Cokendolpher, 1998 , the sixth species of the genus to be described, was collected in Sótano de Poncho, Veracruz. Sissom and Cokendolpher (1998) tentatively agreed with Stockwell’s (1992) recognition of Superstitioniidae at family rank, based on Francke’s (1982a) diagnosis of the subfamily, but expressed reservations about including Troglotayosicus and Belisarius in the family without firm evidence.

A new family, Troglotayosicidae Lourenço, 1998 (as Troglotayosidae), and two monotypic subfamilies, Troglotayosicinae Lourenço, 1998 (as Troglotayosinae), and Belisariinae Lourenço, 1998 (as Belisarinae ), were meanwhile created to accommodate Troglotayosicus and Belisarius respectively, their inclusion in the same family justified solely on the basis of their troglomorphic habitus and relictual distribution ( Lourenço, 1998).

Whereas most subsequent authors (Lourenço, 2000, 2001; Lourenço and Sissom, 2000; Sissom, 2000b; Sissom and Hendrixson, 2005; Soleglad and Fet, 2003; Coddington et al., 2004; Prendini and Wheeler, 2005; Fet and Soleglad, 2005) recognized Superstitionia , Alacran , Sotanochactas , and Typhlochactas in Superstitioniidae , after its initial elevation by Stockwell (1992), there remains little agreement about the taxonomic placements of Troglotayosicus and Belisarius .

According to Sissom (2000a, 2000b) and Fet and Sissom (2000), the transferral of Troglotayosicus and Belisarius from Chactidae to Superstitioniidae was weakly justified, and Troglotayosicidae was not supported by solid characters. Lourenço (2000, 2001) continued to recognise Troglotayosicus and Belisarius as Troglotayosicidae , however. Coddington et al. (2004) also questioned the monophyly of Troglotayosicidae , suggesting that Belisarius may be more closely related to Euscorpiidae Laurie, 1896 (and, less plausibly, to Chactidae ), than to Troglotayosicus , which these authors suggested might be a superstitioniid.

Soleglad and Fet (2003) returned Belisarius to Chactidae and Troglotayosicus to Superstitioniidae , and synonymized Troglotayosicidae with Superstitioniidae , based on a cladistic analysis of scorpion higher phylogeny criticized by Prendini and Wheeler (2005). Prendini and Wheeler (2005) rejected all changes to the suprageneric classification of scorpions proposed by Soleglad, Fet, and colleagues in their self-edited online publication since 2001 and, pending a rigorous and unbiased analysis, reverted to a classification reflected by the most recent peer-reviewed, published treatments which recognized, inter alia, both Superstitioniidae and Troglotayosicidae . In response, Fet and Soleglad (2005) promptly reinstated their previous classification (Soleglad and Fet, 2003), ignoring the problems identified by Prendini and Wheeler (2005), but it was not universally accepted. Lourenço (2006), for example, suggested that Troglotayosicus should be retained in Troglotayosicidae or considered incertae sedis in Chactoidea , while Botero-Trujillo and Francke (2009), who described the second species of Troglotayosicus , also recognised Troglotayosicidae .

In the most recent contributions on the systematics of these scorpions, Francke et al. (2009) described a new species of Typhlochactas , the third putatively endogean species, taken from under a stone in Cañada de La Joya, Queretaro, while Prendini et al. (2009) tested the monophyly and phylogenetic relationships among the nine troglomorphic species with a quantitative cladistic analysis, the first ever conducted in this group of scorpions. The analysis of Prendini et al. (2009), based on 142 phylogenetically informative morphological characters (appendix 1), including eighty-two trichobothrial characters defined strictly on positional homology (the ‘‘placeholder approach’’; tables 3, 4), confirmed the monophyly of the nine ingroup species (fig. 4). The many apomorphies (besides troglomorphies) supporting their monophyly, as distinct from Superstitionia and the other genera variously placed in Superstitioniidae by previous authors (viz. Belisarius and Troglotayosicus ), justifies their elevation to family rank, in accordance with the original views of Mitchell (1968: 770, 771). In the present contribution, we therefore elevate Typhlochactidae , for the first time, from their former rank as subfamily; create Alacraninae , new subfamily to accommodate A. tartarus ; and retain the remaining genera and species in subfamily Typhlochactinae . As with Francke’s (1986) creation of Sotanochactas to accommodate T. elliotti , the many apomorphies supporting the branch leading to T. granulosus versus the monophyletic group comprising the remaining species of Typhlochactas in the analysis of Prendini et al. (2009), justifies their placement in separate genera. We therefore create Stygochactas , new genus to accommodate T. granulosus in a new combination. Based on evidence put forth below, the holotype of S. granulosus is a juvenile and the adult, a complete specimen of which has yet to be discovered, may be similar in size to adult A. tartarus (which measure 60–70 mm in length), thus representing the second large-bodied species in the family.