Bibliography
2022
 © Oto Zimmermann
Authors
doc. RNDr. Jiří Král, Dr., Mgr. Martin Forman, RNDr. Milan Řezáč, Ph.D., Nela Gloríková, Veronika Řezáčová
Abstract

The mygalomorph spiders of the family Atypidae are among the most archaic spiders. The genus Atypus Latreille, 1804 occurs in Eurasia and northern Africa, with a single enigmatic species, Atypus snetsingeri Sarno, 1973, known only from a small area in southeastern Pennsylvania in eastern USA. A close relationship to European species could be assumed based on geographic proximity, but A. snetsingeri more closely resembled Asian species. This study was undertaken to learn more about the genetics of A. snetsingeri, its habitat requirements and natural history. Molecular markers (CO1 sequences) were compared to available data for other atypids and showed that A. snetsingeri is identical with A. karschi Dönitz, 1887 native to East Asia. Natural history parameters in Pennsylvania were also similar in every respect to A. karschi in Japan, therefore, we propose that the spider is an introduced species and the specific epithet snetsingeri is relegated to a junior synonym of A. karschi. Cytogenetic analysis showed an X0 sex chromosome system (42 chromosomes in females, 41 in males) and we also detected nucleolus organizing regions and heterochromatin, the latter for the first time in the Atypoidea. In Pennsylvania the spider is found in a variety of habitats, from forests to suburban shrubbery, where the above-ground webs are usually attached vertically to trees, shrubs, or walls, although other webs are oriented horizontally near the ground. Prey include millipedes, snails, woodlice, carabid beetles and earthworms. Atypus karschi is the first known case of an introduced purse-web spider. It is rarely noticed but well-established within its range in southeastern Pennsylvania.


2021
 © Oto Zimmermann
Authors
RNDr. Milan Řezáč, Ph.D., prof. Mgr. Stano Pekár, Ph.D., Veronika Řezáčová
Abstract
The spiders of the genus Dysdera are renowned for including woodlouse specialists. In the Canary Islands, Dysdera underwent remarkable local diversification, and 48 endemic species have been reported to date. We aim to disentangle the evolutionary history underpinning this diversity, with particular emphasis on the evolution of the trophic ecology. We collected specimens belonging to 17 Dysdera species along with the co-occurring potential prey. We performed prey  capture experiments with these specimens to assess which species accepted woodlice as prey and how they captured them and used statistical extrapolation and published phylogenetic information to infer the evolution of these dietary and behavioral traits. We identified four capture tactics and trait reconstruction analyses that inferred oniscophagy as the ancestral state. We found several instances of polyphagy that evolved from trophic specialist ancestors. When including the trophic strategy, predatory behavior, body size, and habitat type, it was revealed that at all sites, the co-occurring Dysdera species differed by at least one trait, suggesting the role of adaptive radiation via character displacement. We hypothesize that the colonization of the newly emerged islands by the Dysdera species was probably followed by the recurrent evolution of both woodlice specialists and non-oniscophagous species. The radiation of Dysdera in the Canary Islands indicates that diet specialization can evolve to polyphagy.

Statistics

Found

31
Records
22
Species
22
Genera
1
Squares