Venom composition of the Iberian adder (Vipera seoanei) from northern Portugal reveals limited sex and size variation

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  Venom composition of the Iberian adder (Vipera seoanei) from northern Portugal reveals limited sex and size variation Abstract Snake venom is a complex and dynamic ecological trait, with high potential for intraspecific variation. In this study, the venom composition of the Iberian adder ( Vipera seoanei ) from the Peneda Mountains of northern Portugal was investigated to explore whether venom varies with body size and sex. Venom proteomes from six individuals representing juvenile, subadult, and adult males and females were characterised using LC–MS/MS, while individual variation was assessed from SDS–PAGE profiles of 18 snakes. LC–MS/MS identified 144 proteins, dominated by phospholipases A 2 (PLA 2 ), snake venom serine proteases (svSP), and C-type lectin-related proteins (CTL). Descriptive comparisons revealed contrasting individual profiles, particularly between the juvenile male, characterised by high svSP and svMP abundance, and the juvenile female, characterised by high ...

New species of Metagonia Simon with directionally asymmetric male and female genitalia (Araneae, Pholcidae)

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New species of Metagonia Simon with directionally asymmetric male and female genitalia (Araneae, Pholcidae)


Abstract

Genital asymmetry is a rare phenomenon in spiders, and directional asymmetry, where all specimens are same-sided, is particularly scarce. In the New World genus Metagonia, only M. mariguitarensis (González-Sponga, 1998) was previously known to be directionally asymmetric. Here we describe three further species in the genus Metagonia that all share directionally asymmetric male and female genitalia: M. embera Huber sp. nov. (Colombia and Panama), M. uca Huber sp. nov. (Colombia), and M. wayuu Huber sp. nov. (Colombia and Venezuela). Metagonia uca is the species with the most extreme asymmetry and also the only species where female asymmetry is not limited to internal structures but extends to the epigynal scape. Interspecific CO1 distances among these four species ranged from 15.5 to 20.9%. Intraspecific distances mostly ranged from 0.0–1.7%, but higher values were found for M. mariguitarensis (up to 9.1%). While the available evidence suggests that directional asymmetry in Metagonia arose only once (in the last common ancestor of the four species above), the origin of the more widespread asymmetry in Metagonia (female antisymmetry) is less clear. We briefly discuss the phylogenetic pattern of antisymmetry in Metagonia, concluding that further focused research is necessary to provide the basic data for such an analysis.

Huber, B. A., & Meng, G. (2025). New species of Metagonia Simon with directionally asymmetric male and female genitalia (Araneae, Pholcidae). European Journal of Taxonomy, 1026(1), 199–235. https://doi.org/10.5852/ejt.2025.1026.3117