Species delimitation and morphological divergence in Centruroides vittatus

Identifying the correct species is very important in the medical important family Buthidae, as correct identification may be essential for the medical treatment needed in case of envenomations. Species identification and delimitation in Buthidae is often a challenge to scientists because many species exhibit a considerable intraspesific variation in morphology.

Tsunemi Yamashita and Douglas Rhoads have now published a very interesting study conducting a phylogeographic, morphometric and ecological niche modelling analysis of the North American scorpion Centruroides vittatus (Say, 1821) (Buthidae). This paper presents a clarification of the status of the polymorphic C. vitattus in the USA, but also shows how additional methods can be used for understanding species delimitation in phylogeny and taxonomy.

Abstract:
Scorpion systematics and taxonomy have recently shown a need for revision, partially due to insights from molecular techniques. Scorpion taxonomy has been difficult with morphological characters as disagreement exists among researchers with character choice for adequate species delimitation in taxonomic studies. Within the family Buthidae, species identification and delimitation is particularly difficult due to the morphological similarity among species and extensive intraspecific morphological diversity. The genus Centruroides in the western hemisphere is a prime example of the difficulty in untangling the taxonomic complexity within buthid scorpions. In this paper, we present phylogeographic, Ecological Niche Modeling, and morphometric analyses to further understand how population diversification may have produced morphological diversity in Centruroides vittatus (Say, 1821). We show that C. vittatus populations in the Big Bend and Trans-Pecos region of Texas, USA are phylogeographically distinct and may predate the Last Glacial Maximum (LGM). In addition, we suggest the extended isolation of Big Bend region populations may have created the C. vittatus variant once known as C. pantheriensis.

Reference:
Yamashita T, Rhoads DD. Species Delimitation and Morphological Divergence in the Scorpion Centruroides vittatus (Say, 1821): Insights from Phylogeography. PLoS One. 2013; 8(7): e68282. [Free full text]

Thanks to Rolando Teruel and Matt Simon for informing me about this paper!