Major revision of troglomorphic North American scorpions results in a new family and genus

The fantastic troglomorphic and trglobitic scorpions of Mexico have been placed in different families since their discovery. The study of these enigmatic scorpions has been difficult because of their cryptic ecology (some species living deep in narrow caves) and low population numbers. Only 29 specimens have been collected in the last 40 years. The species has until recently been placed in the family Superstitioniidae.

In a recent revision of all known specimens, Valerio Vignoli & Lorenzo Prendini (2009) have redescribed all species and conducted a cladistic analysis. This has resulted in the elevation of the old family Typhlochactidae Mitchell, 1971. In addition, the new genus Stygochactas Vignoli & Prendini, 2009 has been created to accomodate the species S. granulosus (Sissom & Cokendolpher, 1998), previously placed in Typhlochactas Mitchell, 1971.

The following taxa have been transfered from Superstitioniidae to Typhlochactidae:

Alacran tartarus Francke, 1982
Alacran chamuco Francke, 2009 (not in this paper, but published a few weeks ago)
Sotanochactas elliotti (Mitchell, 1971)
Stygochactas granulosus (Sissom & Cokendolpher, 1998)
Typhlochactas cavicola Francke, 1986
Typhlochactas mitchelli Sissom, 1988
Typhlochactas reddelli Mitchell, 1968
Typhlochactas rhodesi Mitchell, 1968
Typhlochactas sissomi Francke et al., 2009
Typhlochactas sylvestris Mitchell & Peck, 1977

Abstract:
The scorpion family Typhlochactidae Mitchell, 1971, endemic to eastern Mexico, comprises nine troglomorphic species specialized for life in hypogean and endogean habitats. Due to their cryptic ecology, inaccessible habitat, and apparently low population density, Typhlochactidae are poorly known. Only 29 specimens have been collected in 40 years. Four species are known from a single specimen, two species are known only from the male and three only from the female. We provide an illustrated revision of the family based on a reexamination of most specimens in the world’s collections, including new specimens collected after the original descriptions and older specimens not previously described. Based on results of a recent cladistic analysis, Typhlochactidae are elevated, for the first time, from their former rank as subfamily, first of Chactidae and, more recently, of Superstitioniidae. Alacraninae, new subfamily is created to accommodate Alacran Francke, 1982. Stygochactas, new genus, is created to accommodate Typhlochactas granulosus Sissom and Cokendolpher, 1998 in a new combination. Sotanochactas Francke, 1986, Stygochactas and Typhlochactas Mitchell, 1971 are retained in subfamily Typhlochactinae Mitchell, 1971. Diagnoses of the family and subfamilies are presented, followed by a key to the genera and species, revised diagnoses of the genera, revised diagnoses and descriptions, tabulated meristic data, and distribution maps of the species. Descriptions and diagnoses are illustrated with ultraviolet fluorescence and visible light photographs, providing a visual atlas to the morphology of these remarkable scorpions. A review of their taxonomic history is provided, the importance of trichobothriotaxy for their systematics discussed, and several misconceptions in the literature clarified.

Reference:
Vignoli V, Prendini L. Systematic revision of the troglomorphic North American scorpion family Typhlochactidae (Scorpiones, Chactoidea). Bulletin of the American Museum of Natural History. 2009; (326):1-94. [Free fulltext]

Family Typhlochactidae