Genomic and transcriptomic analyses reveal the adaptation to semi-aquatic and aquatic life in spiders

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  Genomic and transcriptomic analyses reveal the adaptation to semi-aquatic and aquatic life in spiders Abstract Spiders are largely terrestrial, but some lineages have independently adapted to marine and freshwater habitats. Although physiological and behavioral traits supporting these evolutionary transitions have been characterized, the genomic basis of adaptation to aquatic and semi-aquatic habitats in spiders remains unclear. Here, we report a chromosome-level genome assembly for the aquatic spider Argyroneta aquatica. Comparative analysis of 22 spider species supports two independent transitions in semi-aquatic (∼56 Mya) and aquatic (∼44 Mya) lineages. The aquatic spider show distinct respiratory morphology compared with terrestrial spiders, including anterior spiracles and denser tracheoles. Molecular evolution analyses identified lineage-specific shifts in selective constraint or evidence of positive selection linked to trachea development (e.g., Wnt-1, Catenin beta, TMEM23...

A new species of the trapdoor spider genus Titanidiops Simon (Araneae: Idiopidae) from western Maharashtra, India

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A new species of the trapdoor spider genus Titanidiops Simon (Araneae: Idiopidae) from western Maharashtra, India

ABSTRACT

A new species, Titanidiops kolhapurensis sp. n., is described on the basis of six adult female and three adult male specimens collected from the outskirts of Kolhapur City, western Maharashtra, India. Specimens of both sexes are described in detail and they are distinguished from all other known peninsular Indian congeners of Titanidiops and Idiops in several non-overlapping morphological characters. Notes on natural history, and on intraspecific variation of genital characters, as well as measurements and meristic data of the new species are provided. Additionally, we present preliminary observations on occurrence of the new species and other sympatric habitat specialist taxa in natural and altered/modified habitats from the type locality and nearby localities. We emphasise the urgent need to halt further alteration or modification of the natural habitat of T. kolhapurensis sp. n. and to implement habitat restoration measures to safeguard the new species and other habitat specialists from the imminent risk of local extinction.

Gangalmale, S., Thackeray, T., Khandekar, A., & Gaikwad, S. M. (2026). A new species of the trapdoor spider genus Titanidiops Simon (Araneae: Idiopidae) from western Maharashtra, India. Journal of Natural History, 60(5–8), 399–419. https://doi.org/10.1080/00222933.2025.2603654