Andrés A. Ojanguren-Affilastro

Phylogeny, species delimitation and convergence in the South American bothriurid scorpion genus Brachistosternus Pocock 1893: Integrating morphology, nuclear and mitochondrial DNA.

A phylogenetic analysis of the scorpion genus Brachistosternus Pocock, 1893 (Bothriuridae Simon, 1880) is presented, based on a dataset including 41 of the 43 described species and five outgroups, 116 morphological characters and more than 4150 base-pairs of DNA sequence from the nuclear 18S rDNA and 28S rDNA gene loci, and the mitochondrial 12S rDNA, 16S rDNA, and Cytochrome c Oxidase Subunit I gene loci. Analyses conducted using parsimony, Maximum Likelihood and Bayesian Inference were largely congruent with high support for most clades. The results confirmed the monophyly of Brachistosternus, the nominal subgenus, and subgenus Ministernus Francke, 1985, as in previous analyses based only on morphology, but differed in several other respects. Species from the plains of the Atacama Desert diverged basally whereas the high altitude Andean species radiated from a more derived ancestor, presumably as a consequence of Andean uplift and associated changes in climate. Species limits were assessed among species that contain intraspecific variation (e.g., different morphs), are difficult to separate morphologically, and/or exhibit widespread or disjunct distributions. The extent of convergence in morphological adaptation to life on sandy substrata (psammophily) and the complexity of the male genitalia, or hemispermatophores, was investigated. Psammophily evolved on at least four independent occasions. The lobe regions of the hemispermatophore increased in complexity on three independent occasions, and decreased in complexity on another three independent occasions.

Two new scorpion species from Paposo, in the Coastal desert of Taltal, Chile (Scorpiones, Bothriuridae, Brachistosternus )

Brachistosternus paposo n. sp. and Brachistosternus barrigai n. sp. are described from Paposo, in the coastal transitional desert of northern Chile. Brachistosternus paposo n. sp. is closely related to Brachistosternus roigalsinai Ojanguren-Affilastro 2002, and B. barrigai n. sp. is closely related with Brachistosternus kamanchaca Ojanguren-Affilastro, Mattoni & Prendini 2007.

Dated phylogenetic studies of the southernmost American buthids (Scorpiones; Buthidae)

A dated molecular phylogeny of the southernmost American species of the family Buthidae, based on two nuclear and two mitochondrial genes, is presented. Based on this study, analyzed species of the subgenus Tityus (Archaeotityus) are neither sister to the remaining species of the genus Tityus, nor are they closely related to the New World microbuthids with decreasing neobothriotaxy. Analyzed species of the subgenus Tityus do not form a monophyletic group. Based on ancestral area estimation analyses, known geoclimatic events of the region and comparisons to the diversification processes of other epigean groups from the area, a generalized hypothesis about the patterns of historical colonization processes of the family Buthidae in southern South America is presented. Furthermore, for the first time, a Paleogene-African ingression route for the colonization of America by the family Buthidae is proposed as a plausible hypothesis.

Rumikiru, n. gen. (Scorpiones: Bothriuridae), a New Scorpion Genus from the Atacama Desert

ABSTRACT Rumikiru, n. gen., a new bothriurid scorpion genus from the coastal Atacama Desert, Chile, is described. This is the first scorpion genus endemic to northern Chile. It is most closely related to Pachakutej Ochoa, 2004, from the inter-Andean valleys of Peru. Orobothriurus lourencoi Ojanguren-Affilastro, 2003, is transferred to the new genus and redescribed, creating Rumikiru lourencoi (Ojanguren-Affilastro, 2003), n. comb., and a second species of the genus, Rumikiru atacama, n. sp., is described.

Systematic Revision of the granulatus Group of Urophonius Pocock, 1893 (Scorpiones, Bothriuridae), with Description of a New Species from Central Chile

ABSTRACT A systematic revision of the granulatus group of the bothriurid scorpion genus Urophonius Pocock, 1893 is presented. Urophonius pizarroi, n. sp., a new species from central Chile, is described. Urophonius granulatus Pocock, 1898, Urophonius somuncura Acosta, 2003, and Urophonius tregualemuensis Cekalovic, 1981, are redescribed using modern standards. The adult males of U. somuncura and U. tregualemuensis are described for the first time. A distribution map and key to the species of the granulatus group are provided, along with a discussion of their phenology.

Sex-Linked Chromosome Heterozygosity in Males of Tityus confluens (Buthidae): A Clue about the Presence of Sex Chromosomes in Scorpions.

Scorpions of the genus Tityus show holokinetic chromosomes, achiasmatic male meiosis and an absence of heteromorphic sex chromosomes, like all Buthidae. In this work, we analysed the meiotic behaviour and chromosome rearrangements of a population of the scorpion Tityus confluens, characterising the cytotypes of males, females and embryos with different cytogenetic techniques. This revealed that all the females were structural homozygotes, while all the males were structural heterozygotes for different chromosome rearrangements. Four different cytotypes were described in males, which differed in chromosome number (2n = 5 and 2n = 6) and meiotic multivalent configurations (chains of four, five and six chromosomes). Based on a detailed mitotic and meiotic analysis, we propose a sequence of chromosome rearrangements that could give rise to each cytotype and in which fusions have played a major role. Based on the comparison of males, females and a brood of embryos, we also propose that the presence of multivalents in males and homologous pairs in females could be associated with the presence of cryptic sex chromosomes, with the male being the heterogametic sex. We propose that the ancestral karyotype of this species could have had homomorphic XY/XX (male/female) sex chromosomes and a fusion could have occurred between the Y chromosome and an autosome.

Scorpion Sheds ‘Tail’ to Escape: Consequences and Implications of Autotomy in Scorpions (Buthidae: Ananteris)

Autotomy, the voluntary shedding or detachment of a body part at a determined cleavage plane, is a common anti-predation defense mechanism in several animal taxa, including arthropods. Among arachnids, autotomy has been observed in harvestmen, mites, and spiders, always involving the loss of legs. Autotomy of the opisthosoma (abdomen) was recently reported in a single species of the Neotropical buthid scorpion genus Ananteris Thorell, 1891, but few details were revealed. Based on observations in the field and laboratory, examination of material in museum collections, and scanning electron microscopy, we document autotomy of the metasoma (the hind part of the opisthosoma, or ‘tail’) in fourteen species of Ananteris. Autotomy is more common in males than females, and has not been observed in juveniles. When the scorpion is held by the metasoma, it is voluntarily severed at the joints between metasomal segments I and II, II and III, or III and IV, allowing the scorpion to escape. After detachment, the severed metasoma moves (twitches) automatically, much like the severed tail of a lizard or the severed leg of a spider, and reacts to contact, even attempting to sting. The severed surface heals rapidly, scar tissue forming in five days. The lost metasomal segments and telson cannot be regenerated. Autotomy of the metasoma and telson results in permanent loss of the posterior part of the scorpion’s digestive system (the anus is situated posteriorly on metasomal segment V) and the ability to inject venom by stinging. After autotomy, scorpions do not defecate and can only capture small prey items. However, males can survive and mate successfully for up to eight months in the laboratory. In spite of diminished predation ability after autotomy, survival allows males to reproduce. Autotomy in Ananteris therefore appears to be an effective, adaptive, anti-predation escape mechanism.

Diversidad y composición estacional de la escorpiofauna (Arachnida: Scorpiones) del archipiélago Los Choros (Región de Coquimbo, Chile)

Se estudio la composicion taxonomica, la abundancia y la estructura espacial y temporal de la escorpiofauna presente en el archipielago de Los Choros (Region de Coquimbo, Chile). Se registro la presencia de cuatro especies: Bothriurus coriaceus Pocock 1893, Brachistosternus (Brachistosternus) roigalsinai Ojanguren-Affilastro 2002, Brachistosternus (Brachistosternus) cepedai Ojanguren-Affilastro et al. 2007a (Bothriuridae) y Caraboctonus keyserlingi Pocock 1893 (Caraboctonidae). Se registraron diferencias entre las especies de escorpiones en sus niveles de abundancia total, presencia y abundancia tanto estacional como en los diferentes ambientes pedologicos. El 53,1 % del total de la abundancia correspondio a B. coriaceus, que estuvo presente en ocho de los nueve ambientes pedologicos analizados y mostro actividad en las tres estaciones del ano muestreadas, al igual que Br. roigalsinai, el cual represento el 30,3 % de la abundancia total y fue registrado en siete ambientes pedologicos. La especie Br. cepedai tuvo baja abundancia (4,1 %) y su distribucion estuvo restringida a los ambientes dunarios, en los meses de primavera y verano. Por otra parte, Caraboctonus keyserlingi represento la situacion opuesta, con un 12,5 % de la abundancia, restringida a los ambientes de la isla Choros y a los meses de primavera. No existe una estructuracion temporal, pero es reconocible un patron de estructuracion espacial. En base a estos antecedentes proponemos que las diferencias en las especies, tanto en su densidad, como en las estrategias de uso y ocupacion de los ambientes podrian explicar los patrones observados.

Cytogenetics of three species of scorpions of the genus Brachistosternus from Argentina (Scorpiones: Bothriuridae)

Abstract Meiotic studies on three phylogenetically distant species of the genus Brachistosternus Pocock from Argentina were conducted. One species is from the subgenus Ministernus Francke 1985, B. ferrugineus Thorell 1876, and two species are from the subgenus Brachistosternus Pocock 1893, B. montanus Roig-Alsina 1977 (Andean species group), and morphologically different populations of B. pentheri Mello-Leitão 1931 (plains species group). All species showed achiasmatic meiosis, absence of heteromorphic bivalents, and bibrachial and monobrachial chromosomes of different sizes. Males of Brachistosternus ferrugineus, B. montanus, and one population of B. pentheri have 2n  =  46. Males of the typical populations of B. pentheri have 2n  =  42. These results suggest that B. pentheri may comprise two species.

Arthropod assemblages of the Quebrada del Morel private protected area (Atacama Region, Chile)

Abstract The objective of this baseline study was to use pitfall traps to examine the taxonomic composition and abundance of arthropods in the Quebrada del Morel private protected area located in the Atacama Region (Chile). The study area was divided into 10 vegetationally and pedologically contrasting sites: coastal steppe (CS), ravine bottom (RB), dunes with Prosopis flexuosa (PF), sandy-bottomed ravine (SBR), dunes with Skytanthus acutus (SA), coastal range (CR), piedmont with Nolana sp. (PN), inland dunes (ID), steppe with Nolana sp. (EN), and steppe with Atriplex sp. (EA). A total of 2187 specimens were captured, belonging to 73 species in 31 families. Of these 73 species, 26 belonged to Arachnida, and 47 to Insecta. The two dominant orders of the Arachnida assemblage were Solifugae (22.8% of total capture) and Araneae (5.7%). Insecta accounted for 69.1% of the total capture and was dominated by two orders: Coleoptera (33.8%) and Orthoptera (21.9%). The most abundant arthropod families were the solifuge Mummucidae (22.5%), the coleopteran Tenebrionidae (19.4%), and the orthopteran Gryllidae (18.8%). Particularly important among these families was Tenebrionidae which was represented by 18 species and 11 genera. The sites with the highest abundance of tenebrionids were PF (61.9%) and SBR (11.8%). The highest species diversity was observed in SBR (13) and PF (11). The differences in vegetation between the sites were clearly reflected in the numerical contribution of most taxa. This information will help implement compensation actions, develop a reclamation plan, and consolidate a conservation management plan for the Quebrada del Morel private protected area.