The distribution, spatial clustering, and density of trapdoor spiders in two California coastal dune ecosystems

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  The distribution, spatial clustering, and density of trapdoor spiders in two California coastal dune ecosystems Abstract Coastal dune ecosystems support endemic trapdoor spiders, yet population data for these species are limited. We conducted the first coastal dune trapdoor spider population estimation surveys at Moss Landing State Beach (California) and for Aptostichus stephencolberti Bond 2008 at Sunset State Beach using randomly selected 1m 2 quadrats across ~26,000 m 2 per site. Burrow densities were similar between sites (Sunset: 0.287 burrows/m 2 ; Moss: 0.453 burrows/m 2 ), yielding estimated population sizes of ~35,206 and ~30,959 individuals, respectively. However, spatial analyses revealed contrasting patterns of burrow distribution. At Sunset State Beach, burrow presence was strongly associated with vegetation and occurred closer to plants, despite vegetation being randomly distributed. In contrast, no vegetation–burrow association was detected at Moss Landing, alth...

Alone no more—Integrative taxonomy of New Zealand odd-clawed spiders challenges the monotypy of Pianoa and Gradungula (Araneae: Gradungulidae)

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Alone no more—Integrative taxonomy of New Zealand odd-clawed spiders challenges the monotypy of Pianoa and Gradungula (Araneae: Gradungulidae)

Abstract

The enigmatic spider family Gradungulidae, endemic to Australia and New Zealand, exhibits a combination of morphological characteristics from both modern and early branching lineages. These spiders are rare, challenging to collect, and not well documented, with only 18 described species across seven genera. This study presents the first comprehensive review of the gradungulid fauna in New Zealand, utilising extensive field sampling, molecular phylogenetics, and high-resolution imaging. Previously, this fauna was understood to comprise three monotypic genera: Gradungula, Pianoa and Spelungula. However, we discovered an unexpected diversity of gradungulids in the northern region of New Zealand's South Island, both genetically and taxonomically. This led to the identification of several new candidate species, including Gradungula kahurangi, sp. nov. and Pianoa civis, sp. nov., which are formally described from adult males. Despite high diversity in the north of the South Island, these genera exhibit notable differences in their biogeographical distribution: the forest-dwelling Pianoa and cave-inhabiting Spelungula are climatic relicts with limited distribution ranges and poor dispersal capabilities, whereas Gradungula sorenseni shows a widespread distribution extending to the southernmost region of the South Island. Overall, this study establishes a significant framework for conservation biology concerning some of New Zealand's most iconic yet rare spiders. Additionally, revised and expanded diagnoses of male genitalia for the New Zealand genera are presented.

Michalik, P., Vink, C. J., Ramírez, M. J., Dederichs, T. M., Sirvid, P. J., Pawson, S. M., & Harms, D. Alone no more—Integrative taxonomy of New Zealand odd-clawed spiders challenges the monotypy of Pianoa and Gradungula (Araneae: Gradungulidae). Systematic Entomology, e70006. https://doi.org/10.1111/syen.70006