Remarkable micro-endemism and high congeneric richness: eight new cave-restricted species of Pseudochthonius Balzan, 1892 (Pseudoscorpiones, Chthoniidae) from the Brazilian semi-arid

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  Remarkable micro-endemism and high congeneric richness: eight new cave-restricted species of Pseudochthonius Balzan, 1892 (Pseudoscorpiones, Chthoniidae) from the Brazilian semi-arid Abstract Eight new species of pseudoscorpions belonging to the genus Pseudochthonius Balzan, 1892 are described from the semi-arid region of Brazil. Comprehensive morphological descriptions, diagnostic characters, detailed illustrations, and ecological remarks of the habitats are provided for Pseudochthonius celestialis sp. nov., P. caritas sp. nov., P. patientia sp. nov., P. temperantia sp. nov., P. diligentia sp. nov., P. castitas sp. nov., P. humilitas sp. nov., and P. benignitas sp. nov. In addition, we present a brief discussion of the potential factors underlying the remarkable congeneric species richness observed in this geographically restricted region, as well as the principal threats faced by these species. These findings underscore the importance of conserving caves in order to pr...

DNA metabarcoding to estimate diet overlap between the introduced Joro spider (Trichonephila clavata) and three native orb-weaving spiders

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DNA metabarcoding to estimate diet overlap between the introduced Joro spider (Trichonephila clavata) and three native orb-weaving spiders

Abstract

The introduction of novel generalist predators to new ecosystems can dramatically alter species interactions and established food webs. Invasive predators may contribute to pest control services; however, a net loss of biodiversity can occur if invasives displace natives through intraguild predation or resource competition. Joro spiders (Trichonephila clavata) are an introduced, orb-weaving spider that show rapid range expansion in the United States. Trophic patterns of orb-weaving spiders are largely unknown, and as such, the impact of Joro spiders on established food webs is unclear. We explored patterns of diet composition and prey overlap between Joro spiders and three co-occurring, native orb-weaving species with molecular gut content analysis. In addition, we asked whether the composition of focal native spider diets differed at sites co-inhabited by Joro spiders. We collected female spiders from 52 sites within the Joro spider’s introduced range and analyzed gut content via DNA metabarcoding and high-throughput Illumina sequencing. Despite overlap in many prey taxa consumed, overall diet composition was dissimilar between Joro and native spiders. Joro spider diets were distinct, with at least 26 unique prey taxa not detected in native spider diets. Moreover, native spider diets were similar regardless of whether Joro spiders were present at collection sites. Thus, our initial analysis suggests that while Joro spider diets do overlap with native spiders, their use of many unique food resources does not suggest strong competition. Additional research into web placement and spatial overlap as mechanisms underlying Joro spider invasion success should help clarify the potential for exclusion of native predator populations.

Grabarczyk EE, Schmidt JM (2026) DNA metabarcoding to estimate diet overlap between the introduced Joro spider (Trichonephila clavata) and three native orb-weaving spiders. PLoS One 21(6): e0351929. https://doi.org/10.1371/journal.pone.0351929