PhylogeneticBlackwell Publishing Ltd analysis of the scorpion genus Brachistosternus (Arachnida, Scorpiones, Bothriuridae) ANDRÉS A. OJANGUREN-AFFILASTRO & MARTÍN J. RAMÍREZ Submitted: 16 April 2008 Ojanguren-Affilastro, A. A. & Ramírez, M. J. (2009). Phylogenetic analysis of the scorpion Accepted: 4 October 2008 genus Brachistosternus (Arachnida, Scorpiones). — Zoologica Scripta, 38, 183–198. doi:10.1111/j.1463-6409.2008.00367.x A phylogenetic analysis of the scorpion genus Brachistosternus Pocock (Bothriuridae) is presented. The analysis is based on a data set including 38 of the 41 described species of Brachistosternus plus eight outgroup representatives of seven additional bothriurid genera and one buthid, scored for 116 morphological characters. The cladistic analysis of this matrix under implied weighting results in four most parsimonious trees. The monophyly of genus Brachistosternus is well supported; its subgeneric subdivision is redefined: the subgenera Brachistosternus Pocock and Ministernus Francke are considered valid, whereas Leptosternus Maury is synonymized with Brachistosternus. Illustrations of diagnostic structures are provided. The hemispermatophores of Brachistosternus peruvianus Toledo-Piza and Brachistosternus pegnai Cekalovic are illustrated for the first time. A key to species of Brachistosternus and maps with the distribution of the subgenera and main groups of species are provided. Corresponding author: Andrés A. Ojanguren-affilastro, Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia’, División Aracnología, Avenida Ángel Gallardo 470, 1405DJR, Buenos Aires, Argentina. E-mails: [email protected]; [email protected] Martín J. Ramírez, E-mail: [email protected] Introduction variation, demanding a large number of specimens to clearly The genus Brachistosternus is the most diverse of the family establish their limits. Bothriuridae, with 41 described species, all of them known Several diagnostic characters of Brachistosternus are unusual from arid and semi-arid regions in South America, from in Bothriuridae (see diagnosis below), the most remarkable southern Patagonia to central Ecuador (Cekalovic 1969; being the great complexity of the hemispermatophores (first Ojanguren-Affilastro 2003a). The genus is especially diverse described by San Martín 1969), which are among the most in the coastal deserts in Chile and Peru (Ochoa 2002; complex in the entire order. The shape and development of Ojanguren-Affilastro 2002a, 2005a; Ochoa & Ojanguren- their internal structures varies between species and are very Affilastro 2007; Ojanguren-Affilastro et al. 2007a,b), and in useful in the systematics of the genus. These and other char- high altitudes on the Andes, up to 4500 m (Ochoa & Acosta acteristics led Maury (1973a) to separate this genus in its own 2002; Ojanguren-Affilastro 2003b; Ojanguren-Affilastro & subfamily Brachistosterninae, but subsequent phylogenetic Mattoni 2006). Members of the genus Brachistosternus were analyses (Prendini 2000, 2003) did not support this proposal. reported as the dominant scorpion species in these areas, Maury (1973b) published a short revision of the 15 species reaching about 70% of the scorpion population (Agusto et al. of Brachistosternus known at that time, and described three 2006). different trichobothrial patterns for the genus. Based on Despite being so diverse and abundant, most species these patterns, he divided the genus in three subgenera, (24 out of 41; Table S1 in the Supporting Information) Brachistosternus Pocock, Leptosternus Maury and Microsternus were described within the last 10 years. Several factors have Maury. Microsternus was preoccupied by a beetle, and was later favoured this scarce knowledge of the group. Because all replaced by Ministernus Francke (1985). Maury based this the species are fossorial, until the use of the UV detection subgeneric division almost exclusively on the trichobothrial became a usual technique of collection, the genus was poorly pattern. Many species have been described since Maury’s represented in collections. In addition, most of the species revision, some of them with quite different trichobothrial have a rather uniform external morphology, making very patterns from those originally described by Maury. difficult their identification. Finally, some species with wide Prendini (2003) established the phylogenetic position of geographical distribution display considerable intraspecific Brachistosternus in the family Bothriuridae in a phylogenetic © 2009 The Authors. Journal compilation © 2009 The Norwegian Academy of Science and Letters • Zoologica Scripta, 38, 2, March 2009, pp183–198 183 Phylogenetic analysis of Brachistosternus • A. A. Ojanguren-Affilastro & M. J. Ramírez analysis of the family; according to him the closest genera to used to identify Brachistosternus species follow: Ochoa (2002); Brachistosternus are Tehuankea Cekalovic and Centromachetes Ochoa & Acosta (2002); Ochoa & Ojanguren-Affilastro Lönnberg. This is intriguing because both genera are endemic (2007); Ojanguren-Affilastro (2002a, 2003a,b; 2004b, 2005a); to the forests of southern Chile, being morphologically very Ojanguren-Affilastro & Mattoni (2006); Ojanguren-Affilastro different from Brachistosternus which occurs, almost exclusively, et al. (2007a,b). Three nominal species were not available, as in arid environments. The relationships between species of detailed below. the genus are still unsolved, and most of the characters used Brachistosternus holmbergi Carbonell 1923 was described by Prendini are not informative within the genus. In the from Jujuy province, in northern Argentina (Carbonell 1923). present revision we present a phylogenetic analysis of the The holotype is presumably lost (Ojanguren-Affilastro 2005b). genus, and test its subgeneric classification. We also take The original description does not match any of the known the opportunity to provide a key to species, and distribution species from northern Argentina or southern Bolivia. The maps for the subgenera and main species groups. short description and the published photograph of the holotype suggest that it could be a specimen of B. ehrenbergii Methods (Gervais 1841). However, this species is known from coastal Descriptive terminology follows Maury (1974) for the deserts in northern Chile and Peru, but not in Argentina or hemispermatophores, Vachon (1973) for the trichobothria, any other locality east of the Andes. Brachistosternus holmbergi Cekalovic (1973a) for the androvestigia (a pair of glands is here considered nomen dubium. situated on the dorsal surface of metasomal segment V in Brachistosternus castroi Mello-Leitão 1940 was described adult males of most species), Roig-Alsina & Maury (1981) for from Copiapó in northern Chile (Mello-Leitão 1940). We have the male telson gland, and Stahnke (1970) for the metasomal studied a specimen identified by Mello-Leitão as B. castroi, carinae, which are abbreviated as follows: DL, dorsolateral; most probably the one used by him to redescribe the species LIM, lateral inframedian; LSM, lateral supramedian; PL, in his revision of 1945. This specimen does not correspond to paralateral; PM, paramedian; VL, ventrolateral; VM, ventro- any of the other species known from the area. We have pre- median. Terminology for pedipalp carinae are according to ferred not to include this specimen in our analysis because it Prendini (2000), and are abbreviated as follows: DI, dorsal is a poorly preserved female juvenile, in which about a 70% internal; DE, dorsal external; VI, ventral internal; VE, ventral of the characters used in our matrix cannot be scored. More external. Illustrations were produced using a Leitz stereomicro- specimens from the type locality should be collected in order scope with camera lucida. Measurements were taken with an to clarify the taxonomic position of this species. ocular micrometer. Hemispermatophores were dissected Brachistosternus simoneae Lourenço 2000, was described from surrounding tissues and observed in 80% ethanol. from Serranopolis (Goias), in an area of Cerrados vegetation Specimens examined are listed in Appendix S3. Abbreviations in central Brazil (Lourenço 2000). We could not study the of collections from which material was studied are as follows: female holotype and only known specimen of the species. AMNH, American Museum of Natural History, New York; Lourenço (2000) only reports as diagnostic some characters ARA, Arturo Roig Alsina personal collection, Buenos Aires, that would distinguish this species from its closest relative, Argentina; CDA, Cátedra de Diversidad Animal I, Universidad B. ferrugineus (Thorell 1876). However, these characters de Córdoba, Argentina; FKCP, Frantisek Kovarík Personal (11 ventral trichobothria on the pedipalp chela; absence of collection; LEULS, Laboratorio de Entomología, Universi- a reticular pigmented spot on the dorsal surface of the dad de La Serena, Chile; MACN-Ar, Museo Argentino de chelicerae) are known to occur in specimens of B. ferrugineus Ciencias Naturales ‘Bernardino Rivadavia’, National Arachno- (Maury 1974; Ojanguren-Affilastro 2005b), which is a highly logical Collection, Argentina; MUSM, Museo de historia variable species. Brachistosternus ferrugineus is one of the most Natural, Universidad Nacional Mayor de San Carlos, Lima, abundant species of Chaco and Espinal biogeographical Perú; MHNC, Museo de Zoologia de la Universidad San provinces from Argentina, Bolivia and Paraguay, and very Antonio Abad, Cusco, Peru; MZUC, Museo Zoológico del common in environments