RESUMO
The Caatinga is a nucleus of seasonally dry tropical forest (SDTF) known as a hotspot of diversification and endemism. Despite its importance, this biome is still insufficiently sampled, resulting in extensive knowledge gaps regarding its species richness and composition. In this study we report two species of Xenoctenidae that are endemic to, and widely distributed in the Caatinga. We redescribe and illustrate Odo vittatus (Mello-Leito, 1936), the only xenoctenid species previously known from the Caatinga. We transfer this species to Xenoctenus Mello-Leito,1938, a genus currently known from six species restricted to Argentina, Bolivia, and Colombia. We also newly describe the male of Xenoctenus vittatus comb. nov. and provide new records of this species, which was hitherto known only from the type-locality, throughout the Caatinga and nearby semiarid vegetation formations. We also describe and illustrate a new species, Xenoctenus kaatinga sp. nov., based on males and female specimens collected throughout the Caatinga. Additionally, we propose diagnostic characters for Xenoctenus and redescribe the type-species, X. unguiculatus.
Assuntos
Aranhas , Animais , Feminino , Masculino , Brasil , Ecossistema , FlorestasRESUMO
Genital traits are among the fastest to evolve, and the processes that drive their evolution are intensively studied. Spiders are characterized by complex genitalia, but the functional role of the different structures during genital coupling is largely unknown. Members of one of the largest spider groups, the retrolateral tibial apophysis (RTA) clade, are characterized by a RTA on the male palp, which is thought to play a crucial role during genital coupling. However, the RTA was lost in several families including the species-rich wolf spiders (Lycosidae) leading to the hypothesis that the genital coupling is achieved by alternative mechanisms. Here, we investigate the genital interactions during copulation in the wolf spider Agalenocosa pirity (Zoicinae) on cryofixed mating pairs using electron, optical and X-ray microscopy and compare our findings with other lycosids and entelegyne spiders. We found an unprecedented coupling mechanism for lycosid spiders involving the palea and a membranous cuticle folding adjacent to the epigynal plate. Additionally, we show an uncommon coupling between the median apophysis and the contralateral genital opening, and confirmed that the terminal apophysis acts as functional conductor, as previously hypothesized for males of Zoicinae. Phylogenetic mapping of RTA indicated that the basal tibial process found in Agalenocosa is a secondary acquisition rather than a modified RTA.
Assuntos
Copulação/fisiologia , Aranhas/anatomia & histologia , Aranhas/fisiologia , Animais , Feminino , Processamento de Imagem Assistida por Computador , Masculino , Filogenia , Reprodução , Aranhas/classificação , Aranhas/ultraestrutura , Tíbia/anatomia & histologiaRESUMO
Pavocosa sp. (Lycosidae) burrows found in an open sparsely vegetated area on the edge of the Gran Salitral saline lake, in central Argentina, are described. Burrows were studied by capturing the occupant and casting them with dental plaster. The hosting sediments and vegetation were also characterized. Inhabited Pavocosa sp. burrows display distinctive features as open, cylindrical, nearly vertical, silk lined shafts about 120 mm long, subcircular entrances, a gradual downward widening, and a particularly distinctive surface ornamentation in the form of sets of two linear parallel marks at a high angle to the burrow axis. Instead, casts of vacated Pavocosa sp. burrows showed some disturbances caused either by the reoccupation by another organism or by predation of the dweller. Two morphologies are related to reoccupation of burrows: those with a structure in form of an "umbrella" and another with smaller excavations at the bottom of the burrow. Predation by small mammals produces funnel-shaped burrows. Both active and abandoned Pavocosa sp. burrow casts are compared with existing ichnogenera and inorganic sedimentary structures, highlighting its distinction. It is argued that key features like the presence of a neck, a downward widening and the described surface texture will allow recognition of wolf spider burrows in the fossil record. However, the putative spider burrows described in the literature either lack the necessary preservational quality or do not show ornamentation similar to the modern wolf spider burrows. Fossil wolf spiders are recorded since the Paleogene (possibly Late Cretaceous), therefore Cenozoic continental rocks can contain wolf spider burrows awaiting recognition. In addition, the particular distribution of Pavocosa sp. in saline lakes may imply that this type of burrow is linked to saline environments.
RESUMO
The lycosid genus Agalenocosa Mello-Leitão, 1944 comprises at least eight species from northern and eastern Argentina and neighbouring countries: Agalenocosa velox (Keyserling, 1891) comb. nov. (from southern Brazil and Argentina), transferred here from Pirata Sundevall, 1833, A. tricuspidata (Tullgren, 1905) comb. nov. (from northwestern Argentina), transferred here from Pardosa C.L. Koch, 1847, A. luteonigra (Mello-Leitão, 1945) (from Argentina and Uruguay), A. punctata Mello-Leitão, 1944 (from Buenos Aires and Entre Ríos, Argentina), A. gentilis Mello-Leitão, 1944 (from Buenos Aires, Argentina), and three new species: A. pirity sp. nov., A. gamas sp. nov. (from eastern Argentina), and A. grismadoi sp. nov. (from eastern Argentina and Paraguay). Agalenocosa singularis Mello-Leitão (type species of the genus) is considered a junior synonym of A. velox. Agalenocosa fimbriata Mello-Leitão, 1944 is considered species inquirenda; Agalenocosa bryantae (Roewer, 1951), A. chacoensis (Mello-Leitão, 1942), A. denisi (Caporiacco, 1947), A. kolbei (Dahl, 1908), A. melanotaenia (Mello-Leitão, 1941), A. pickeli (Mello-Leitão, 1937), A. yaucensis (Petrunkevitch, 1929), A. fallax (L. Koch, 1877), A. helvola (C. L. Koch, 1847), A. subinermis (Simon, 1897) are considered misplaced species. The subfamily placement of Agalenocosa is briefly discussed, and it could be placed in either Piratinae Zyuzin, 1993 or Venoniinae Lehtinen & Hippa, 1979.
Assuntos
Biodiversidade , Aranhas/anatomia & histologia , Aranhas/classificação , Animais , Feminino , Masculino , América do SulRESUMO
The wolf spider genus Birabenia Mello-Leitão, 1941 is revalidated, comprising B. birabenae Mello-Leitão (type species) and B. vittata (Mello-Leitão) comb. n. The monotypic genus Melloicosa Roewer is synonymised with Birabenia by the transfer of its type species Gnatholycosa vittata Mello-Leitão. Three species, Hogna taeniata (Mello-Leitão), Geolycosa sanogastensis (Mello-Leitão) and Paratrochosina murina (Mello-Leitão) are considered junior synonyms of B. birabenae. Representatives of Birabenia show affinities with Trochosa C. L. Koch but can be distinguished by the presence of one pair of apical spines or none on the ventral side of tibia I of females, the presence of four teeth on the cheliceral retromargin, a shorter furrow on the prolateral side of the tegulum on the male bulb and by having more than seven macrosetae at the tip of cymbium. Birabenia is distributed from north-western Argentina to southern Uruguay.
Assuntos
Aranhas/anatomia & histologia , Aranhas/classificação , Distribuição Animal , Animais , Argentina , Feminino , Masculino , Especificidade da Espécie , UruguaiRESUMO
The araneomorph spider family Palpimanidae is reported from Bolivia for the first time. Two new species: Otiothops kathiae and O. naokii are described and illustrated based on specimens recently collected in Santa Cruz Department. Additionally, Fernandezina pulchra Birabén, 1951 previously known only from Formosa, in northern Argentina, is newly recorded from Santa Cruz, and the female is described for the first time. Potential relationships with previously described species are also briefly discussed.
Assuntos
Aranhas/classificação , Distribuição Animal , Animais , Bolívia , Feminino , Masculino , Especificidade da Espécie , Aranhas/anatomia & histologia , Aranhas/fisiologiaRESUMO
A new species of the orb-weaving spider genus Aculepeira Chamberling & Ivie 1942, A. morenoae new species, is described and illustrated based on male and female specimens from the Argentinean natural flooding pampas grasses.