Plucking with the plectrum: phylogeny of the New World buthid scorpion subfamily Centruroidinae Kraus, 1955 (Scorpiones: Buthidae) reveals evolution of three pecten-sternite stridulation organs

Abstract

All New World buthid scorpions except one South American genus, Ananteris Thorell, 1891, comprise a monophyletic group. The monophyly of two subfamilies, Centruroidinae Kraus, 1955 (= Rhopalurusinae Bücherl, 1971) and Tityinae Bücherl, 1971, proposed to accommodate a subset of these genera, has never been tested. The genera accommodated within Centruroidinae are diverse and poorly defined. Prior to the research presented here, Rhopalurus Thorell, 1876 had a disjunct distribution in the Greater Antilles, the Guiana Shield of northern South America, and northeastern Brazil, where Physoctonus Mello-Leitão, 1934 and Troglorhopalurus Lourenço et al., 2004 also occur. The generic distinction between Rhopalurus and Centruroides Marx, 1890, the most speciose genus of Centruroidinae, distributed from the midwestern United States to northern South America, and throughout the Caribbean, was also unclear. Previous studies suggested Centruroides was paraphyletic with respect to Rhopalurus and vice versa. The study presented here, the first rigorous test of the monophyly of Centruroidinae and its component genera, is based on 90 morphological characters and 4,260 aligned base-pairs of DNA sequence from three mitochondrial and two nuclear DNA loci for 102 terminal taxa, representing 24 species in seven ingroup genera, and nine species in three outgroup genera. Molecular and morphological data, analyzed separately and simultaneously, yielded congruent results. Centruroidinae was monophyletic whereas Tityinae was paraphyletic. Centruroides was monophyletic whereas Rhopalurus was paraphyletic, comprising several monophyletic groups congruent with its disjunct distribution. The results of this analysis justify the redefinition of Rhopalurus and Troglorhopalurus, the revalidation of Heteroctenus Pocock, 1893, and the recently created genera Ischnotelson Esposito et al., 2017 and Jaguajir Esposito et al., 2017. The phylogeny indicates that three distinct types of pecten-sternite stridulation organ evolved in Heteroctenus, Jaguajir and Rhopalurus.