Castaways: the Leeward Antilles endemic spider genus Papiamenta (Araneae: Pholcidae).

Ninetinae is a group of small to tiny short-legged spiders largely restricted to arid habitats. Among daddy-long-legs spiders (Pholcidae) this is by far the least diverse subfamily but this may partly be a result of inadequate collecting, poor representation in collections or scientific neglect. We build on a large recent collection of the ninetine genus Papiamenta Huber, 2000 from the Leeward Antilles and use cytochrome oxidase 1 (COI ) sequences, extensive scanning electron microscopy data, transmission electron microscopy data and karyotyping to analyse this geographically isolated and poorly known island genus. COI sequences support the split between the two morphologically distinct species on Curaçao but genetic distances between these are surprisingly low (7.4-9.8%; mean 8.6%). The type species P. levii (Gertsch, 1982) may include more than one species but COI and morphology suggest conflicting clade limits. A third species, P. bonay Huber sp. nov. is newly described from Bonaire. Our data on sperm ultrastructure and karyology are puzzling as these suggest different phylogenetic affinities of Papiamenta to other genera. Males transfer sperm as individual sperm (cleistosperm), agreeing with the putative closest relatives as suggested by molecular data, the North American genera Pholcophora and Tolteca . The sex chromosome system (X 1 X 2 X 3 Y ) of P. levii , however, is as in the South American Ninetinae genera Gertschiola and Nerudia but different from the putative closest relatives. ZooBank: urn:lsid:zoobank.org:pub:7A6A2E84-3A61-4637-AF6F-0E31A9FA79A8.

Reproductive diapause influences spermatogenesis and testes' size in the diplochronous wolf spider Allocosa senex (Lycosidae, Araneae) - A case study using a non-experimental approach.

Seasonality considerably impacts on the life of organisms and leads to numerous evolutionary adaptations. Some species face seasonal changes by entering a diapause during different life stages. During adulthood, a diapause in the non-reproductive period can affect male gametogenesis as, for example, it occurs in insects. Spiders are distributed worldwide and show a variety of life cycles. However, data on spiders' life cycles and seasonal adaptations are limited. Here, we explored the effect of reproductive diapause in a seasonal spider for the first time. We used the South American sand-dwelling spider Allocosa senex as a model as this species is diplochronous, meaning that individuals live two reproductive seasons, with juveniles and adults overwintering in burrows. It has been observed that individuals of this species reduce their metabolism during the non-reproductive season, diminishing prey consumption and locomotion to a minimum. This species is also well-known for exhibiting wandering and courting females and sedentary males. We analyzed spermatogenesis throughout the male's life cycle and described the male's reproductive system and spermiogenesis using light and transmission electron microscopy. We found that spermatogenesis in A. senex is asynchronous and continuous. However, when males face the non-reproductive season, the late spermatogenic stages and spermatozoa decline, causing an interruption but not a total arrest of this process. This seasonality is also reflected in smaller testes' size in males from the non-reproductive season than in other periods. The mechanisms and constraints are unknown, but they could be related to the metabolic depression during this life cycle period. Since sex-role reversal apparently sets a low-intensity sperm competition scenario compared with other wolf spiders, surviving two reproductive seasons may balance mating opportunities by distributing them between both periods. Thus, the partial interruption of spermatogenesis during diapause could allow new mating encounters during the second reproductive season.

Evolutionary morphology of sperm in pholcid spiders (Pholcidae, Synspermiata).

BACKGROUND: Pholcidae represent one of the largest and most diverse spider families and have been subject to various studies regarding behavior and reproductive biology. In contrast to the solid knowledge on phylogeny and general reproductive morphology, the primary male reproductive system is strongly understudied, as it has been addressed only for few species. Those studies however suggested a high diversity of sperm and seminal secretions across the family. To address this disparity and reconstruct the evolution of sperm traits, we investigate the primary male reproductive system of pholcid spiders by means of light, X-ray, and transmission electron microscopy using a comprehensive taxon sampling with 46 species from 33 genera, representing all five subfamilies. RESULTS: Our data show a high disparity of sperm morphology and seminal secretions within pholcids. We document several sperm characters that are unique for pholcids, such as a helical band (Pholcinae) or a lamellate posterior centriolar adjunct material (Modisiminae). Character mapping revealed several putative synapomorphies for individual taxa. With regard to sperm transfer forms, we found that synspermia occur only in the subfamily Ninetinae, whereas the other subfamilies have cleistospermia. In several species with cleistospermia, we demonstrate that spermatids remain fused until late stages of spermiogenesis before ultimately separating shortly before the coiling process. Additionally, we explored the previously hypothesized correlation between sperm size and minimum diameter of the spermophor in the male palpal organ. We show that synspermia differ strongly in size whereas cleistospermia are rather uniform, but neither transfer form is positively correlated with the diameter of the spermophor. CONCLUSIONS: Our data revealed a dynamic evolution of sperm characters, with convergences across all subfamilies and a high level of homoplasy. The present diversity can be related to subfamily level and allows for assignments of specific subtypes of spermatozoa. Our observations support the idea that Ninetinae are an ancestral clade within Pholcidae that have retained synspermia and that synspermia represent the ancestral sperm transfer form of Pholcidae.

The innervation of the male copulatory organ of spiders (Araneae) - a comparative analysis.

BACKGROUND: Nervous tissue is an inherent component of the many specialized genital structures for transferring sperm directly into the female's body. However, the male copulatory organ of spiders was considered a puzzling exception. Based on the recent discovery of nervous tissue in the pedipalps of two distantly related spider species, we investigated representatives of all major groups across the spider tree of life for the presence of palpal nerves. We used a correlative approach that combined histology, micro-computed tomography and electron microscopy. RESULTS: We show that the copulatory organ is innervated in all species investigated. There is a sensory organ at the base of the sperm transferring sclerite in several taxa and nervous tissue occurs close to the glandular tissue of the spermophor, where sperm are stored before transfer. CONCLUSIONS: The innervation of the copulatory organ by the bulb nerve and associated efferent fibers is part of the ground pattern of spiders. Our findings pave the way for unraveling the sensory interaction of genitalia during mating and for the still enigmatic mode of uptake and release of sperm from the male copulatory organ.