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 ...

One time only: determining spider diversity along a latitudinal gradient in South Africa's arid Succulent Karoo and Desert biomes using a rapid sampling protocol

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One time only: determining spider diversity along a latitudinal gradient in South Africa's arid Succulent Karoo and Desert biomes using a rapid sampling protocol

Abstract

The Succulent Karoo Biome (SKB) is distributed in the western and southern parts of South Africa and is an entirely arid global biodiversity hotspot, but it is severely undersampled for spiders. To address this gap, we used a standardized sampling protocol to collect arachnids from four biotopes (open plain, riparian vegetation, east- and west-facing mountain slopes) using three methods along a latitudinal gradient of five adjacent degree-squares in South Africa's arid western interior to determine how latitude, biotopes, sampling methods and climate affect spider assemblages and diversity. A total of 6497 spiders were collected, representing 305 species and 39 families. Beating yielded the most individuals but the fewest species (n = 3710, S = 130), hand collecting in litter the most species and intermediate numbers (n = 1646, S = 213) and hand collecting from rocks collected the lowest numbers and intermediate species richness (n = 1141, S = 150). Abundance and species richness showed a general bell-shaped pattern along the transect, peaking at Akkerendam Nature Reserve (n = 1839, S = 129). Hand collecting from leaf litter was the most important contributor to spider species richness, with a lower species accumulation rate than beating or hand collecting from rocks. Spider composition from rocks and leaf litter showed some overlap, whereas beating sampled a highly distinct fauna across sites. In total, 519 specimens were sequenced (cytochrome c oxidase subunit I, COI), and this data is publicly available on the SPIZA project on the Barcode of Life Data System (BOLD).
Haddad, C. R., Van der Mescht, A., Booysen, R., Christiaan, R., Stander, A., Dippenaar-Schoeman, A. S., Van Aardt, A. C., & Foord, S. H. (2026). One time only: Determining spider diversity along a latitudinal gradient in South Africa's arid Succulent Karoo and Desert biomes using a rapid sampling protocol. Acta Oecologica, 132, 104186. https://doi.org/10.1016/j.actao.2026.104186