A new species of the gnaphosid genus Aphantaulax Simon, 1878, A. rostrata n. sp., is described from Chaiyaphum Province, Thailand. The male of A. fasciata Kulczyński, 1911 is described here for the first time, based on specimens collected from deciduous forests of north-eastern Thailand. This discovery expands the distribution range of the species northwards.

A generally common impression seems to be that the mygalomorphs have simple repertoires of behaviours, but many authors have concluded that this traditional portrayal of mygalomorph behaviours is misleading. An increasing number of studies of reproductive behaviour of mygalomorphs have revealed intricate and complex mechanisms of communication employed by this group. Our objective was to provide a synthetic treatment of the literature published in the last 21 years about sexual behaviour of mygalomorph spiders, in order to contribute in improving our understanding on the widespread and unique behaviours they exhibit. We provide a brief introduction to reproductive behaviour of mygalomorph spiders, and then examine some of the general patterns of courtship and mating behaviours known on some mygalomorph families.

Predators such as spiders are particularly vulnerable to habitat fragmentation and are considered good bio-indicators of nature conservation or habitat degradation. As occurs all around the globe, the Uruguayan coastal sand dunes have been drastically diminished and fragmented, and seriously affected by human modifications such as urbanization, tourism, and introduction of exotic species. The objectives of the present study were to identify the indicator species of two adjacent areas of the sandy coastline of Uruguay (Marindia, Canelones) and, specifically, to confirm whether Allocosa brasiliensis can be considered a biological indicator of the open dunes with scarce psammophile vegetation in this locality. We used the IndVal method which quantifies the indicator value of each species. Allocosa brasiliensis had the highest indicator value for open dunes fixed with psammophilic native vegetation, reflecting its greatest specificity and fidelity to this environment.

Examined specimens of Ceraticelus fissiceps (O. Pickard-Cambridge, 1874) and C. vesperus Chamberlin & Ivie, 1939 were indistinguishable in diagnostic characters, apart from some variation in clypeal slope. Statistical analysis shows no geographic cline between putative species, but rather greater variability of this character in the western spiders. There was also variation among specimens within each putative species in degree of development of the tooth of the apophysis of the male palpal tibia. Ceraticelus vesperus is therefore synonymized with C. fissiceps, Ceraticelus fissiceps is redescribed, and a lectotype is designated. The role of online tools that allow curators to identify and compare their holdings is noted.

Strong reproductive barriers are expected between similar species that co-occur in time and space. We experimentally analysed sexual interactions between the theraphosids Acanthoscurria suina and Eupalaestrus weijenberghi which met those conditions. Unexpectedly, males courted on heterospecific female cues. Furthermore, A. suina females seemed to be more receptive to heterospecific males than conspecific ones in early courtship. Although precopulatory confusion occurred, no interspecific copulations were observed, which indicate that reproductive barriers operate.

Females of most arthropod species mate with more than one male during their lifetime and can store sperm for extensive periods. Consequently, male adaptations to sperm competition and cryptic female choice are the main factors that determine paternity success. In order to understand the processes that lead to differential fertilization success, the relative number of sperm transferred and the number of sperm stored by the female need to be established. To this end, a reliable sperm counting procedure is required. We assessed the reliability and variability of sperm counts in the nuptial-gift-giving spider Pisaura mirabilis (Clerck, 1757) by comparing counts from the same sample and by comparing different storage treatments before sperm counts. We used male sperm storage organs (pedipalps) that were processed immediately after dissection, pedipalps fixed in 80% ethanol and stored at room temperature, and pedipalps that were frozen at -20°C, -40°C, -80°C. We further tested for an influence of the counting solution (CASY®ton versus saline-triton-x buffer) on reliability and variability. The sperm counting protocol resulted in homogeneous distribution of sperm over the counting chamber and highly correlated counts drawn from one sample. Although all treatments kept the sperm in a good state, the samples previously stored in ethanol contained many broken bits of material, which made the counting procedure considerably more time consuming. The buffer used had no effect on the homogeneity and number of sperm found. Whether and how the material was fixed had no significant effect on the average number of sperm found in the palps.