Nelson Ferretti

Un nouveau genre de tarentule (Theraphosidae, Ischnocolinae) endémique du sud du Pérou. Nous proposons la création d'un nouveau genre d'araignées mygalomorphes au sein de la famille des Theraphosidae Thorell, 1869, provenant de la province de Calca, dans le département de Cusco, au Pérou. Nous décrivons le genre monotypique Allpamayu n. gen. et son espèce type Allpamayu suyuwixsa n. gen., n. sp. Allpamayu n. gen. se distingue des Ischnocolinae Simon, 1892 connues par la combinaison originale de caractères suivante: abdomen strié, labium présentant un faible nombre de cuspules et trichobothries claviformes sur les tarses, formant deux rangées parallèles sur la moitié de la longueur du tarse. De plus, le bulbe palpal des mâles présente deux carènes, une tumescence ventrale métatarsienne existe sur la première paire de pattes, le cymbium est muni de longues soies dressées, et les spermathèques des femelles comportent de grands réceptacles subquadrangulaires et un canal court et large, orienté latéralement et pointant vers le haut, portant deux à trois lobes arrondis.

Two previously unknown mygalomorph spider species belonging to two families are described from the south-central Andean region of Peru. Within the family Pycnothelidae, Acanthogonatus goloboffi sp. n. is described, diagnosed and illustrated based on a female from Ccochirhuay, Cusco. The female of this species differs from most known Acanthogonatus by the shape of the spermathecae, which possess two single receptacles lacking additional projections or chambers. It further differs from congeners sharing a single receptacle by having non-spiraled ducts with a well-defined constriction and outwardly directed spherical receptacles. This represents the second record of the genus Acanthogonatus in Peru. Within the family Rhytidicolidae, Fufius agualaniensis sp. n. is described, diagnosed and illustrated based on a female from Agualani, Puno. The female of this species is distinguished from congeners by the following combination of characters: a straight fovea; a sternum as wide as long; a labiosternal junction with a well-developed septum; a preening comb on metatarsus IV consisting of seven large spines in a single row; and spermathecae with a wide, inwardly curved stalk giving rise to three sinuous branches ending in digitiform or domed structures. This constitutes the first formal record of the family Rhytidicolidae from Peru.

The present study contributes to the understanding of the diversity within the tarantula genus Euathlus Ausserer, 1875. Through a combination of cladistic, molecular, and morphological analyses, three new species are described: Euathlus basalticus sp. nov. from Neuquén, Euathlus kupal sp. nov. from Mendoza, and Euathlus susanae sp. nov. from the La Pampa-Mendoza provinces. Additionally, the female of Euathlus tenebrarum Ferretti, 2015 is described for the first time, revealing that the previously attributed female of this species belongs to E. basalticus sp. nov. Phylogenetic trees from both morphological and molecular datasets are presented. Preliminary molecular analyses reveal the identity and support the proposal of the species treated here. Morphological analyses found considerable diversity within Euathlus , particularly in genitalic structures, challenging the general assumption of morphological homogeneity among mygalomorph spiders. Cladistic analyses recovered the genus Phrixotrichus within Euathlus , though this hypothesis could not be tested with molecular data due to the lack of available sequences for Phrixotrichus . These results suggest that future taxonomic revisions may be complemented once molecular data become available. Altogether, our results provide new insights into the systematics and diversity of Euathlus and highlight the importance of integrative approaches for unraveling evolutionary relationships within this group.

The name Grammostola australis Gerschman et Schiapelli, 1948, syn. resurr. is herein resurrected from synonymy with G. inermis Mello-Leitão, 1941, based on morphological and molecular evidence. The holotypes of both species are redescribed, and the female of G. australis is described for the first time. Diagnoses of these species are also provided. Phylogenetic analyses recovered G. inermis as a distinct lineage from G. australis, suggesting that both species are more closely related to Brazilian and Uruguayan species of the genus Grammostola Simon, 1892, than to other Argentinean species. Similarly, Chilean species appear distinct from other Grammostola species, indicating that the Andes act as a geographical barrier.

The family Pycnothelidae comprises medium to small-sized spiders that construct silk tubes under stones or logs or dig burrows in open environments. In Argentina, Acanthogonatus centralis Goloboff, 1995 and Stenoterommata platensis Holmberg, 1881 are two species commonly found in central region, associated to the mountainous grasslands or to the La Plata River Basin. The Tandilia mountainous grassland is an extended belt located southeastern Buenos Aires province, Argentina. Although some pycnothelid spiders are distributed close to this mountainous system, they are not recorded in Tandilia. Through niche modeling we attempt to evaluate the influence of bioclimatic variables in shaping the distribution of these species and explore their absence in the mountainous belt under past, present and future climatic conditions. We found that Tandilia is a non-suitable area for the establishment of the populations of these species with the exception of Stenoterommata platensis under a future scenario of climatic change.

Descrevemos e ilustramos uma nova espécie de tarântula do gênero Plesiopelma de Lavalleja e Maldonado, Uruguai. Plesiopelma arevaloae sp. nov. é distinguida de outras espécies conhecidas por caracteres morfológicos e evidências moleculares.

Thermal preference and thermal performance are used to describe the thermal biology of an ectothermic organism through parameters, i.e., estimating locomotor performance by maximum running speed. In this study, we assessed the thermal preference and locomotor performance of the spider Mecicobothrium thorelli Holmberg, 1882, a wintry mygalomorph spider endemic to the native mountainous grasslands of central Argentina and Uruguay. The preferred temperatures of the 72.4% of the individuals were in the range of 10–20 °C. The highest frequencies of preferred temperatures were 10–15 °C in males and 15–20 °C in females. The sprint speed showed significant differences between all the temperatures evaluated and showed the highest speeds at 25 °C and the lowest at 3 °C. The optimal temperature was 26.09 °C, which was significantly higher than the preferred temperature in both males and females. We concluded that M. thorelli selects a wide range of temperatures and prefers to stay in medium and low temperatures, which are correlated with winter activity in the wild. However, the species showed maximum speed at higher temperatures, which implies that spiders would perform even better in nature and maximize their locomotion by being active during a warmer period.

Une nouvelle petite espèce d'Acanthogonatus Karsch, 1880 (Mygalomorphae, Pycnothelidae) de Patagonie argentine: description d'A. messii Signorotto & Ferretti n. sp. et son emplacement phylogénétique. Une nouvelle espèce de Pycnothelidae Chamberlin, 1917 de la steppe patagonienne, Chubut, Argentine, est décrite et illustrée. Acanthogonatus messii Signorotto & Ferretti n. sp. diffère des autres espèces du genre par le bulbe copulateur du mâle avec une partie basale étroite et la carène de l′embolus légèrement développée en conjonction avec la présence de fortes épines sur le métatarse ventral I, les femelles ayant des spermathèques avec des réceptacles ovales courts, et des expansions internes digitiformes partant de leur base. Il s′agit d′une petite espèce qui construit des terriers dans des environnements ouverts sablonneux avec de petits arbustes. Les résultats de l′analyse phylogénétique montrent qu′elle est proche d′A. birabeni Goloboff, 1995 et d′A. chilechico Goloboff, 1995 dans le groupe “patagonicus”.

Reportamos un nuevo registro en la distribución geográfica de Chaco tucumana en la provincia de Salta, norte de Argentina. Es la localidad más al norte conocida para la especie. Además, presentamos datos sobre la historia natural de la especie y mapas de distribución incluyendo comentarios de las provincias biogeográficas y ecorregiones involucradas.