Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon

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  Beyond Venom and Constriction: Bite Performance and Trophic Ecology in the Genus Drymarchon Abstract Snakes exhibit extreme cranial kinesis that facilitates ingestion of prey with large cross-sectional area, but this ability is widely predicted to reduce bite performance due to decreased structural rigidity. Consequently, most large-bodied snakes rely on envenomation or constriction to subdue prey prior to ingestion. Species within the genus Drymarchon represent a notable exception: these large, non-venomous, non-constricting snakes routinely consume a wide range of prey, including large and potentially dangerous vertebrates, using only simple seizing and pinioning behaviors. Here, we quantify bite performance in three species of Drymarchon ( D. corais, D. couperi, and D. melanurus ), examine morphological predictors of biting performance, compare biting pressure to constriction pressure in similarly sized snakes, and synthesize dietary records across the genus. Our results sh...

Insights into the distribution and ecology of the funnelweb spider Macrothele calpeiana in Portugal

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Insights into the distribution and ecology of the funnelweb spider Macrothele calpeiana in Portugal

Abstract

Biodiversity surveys are critical to prevent decline and extinction of ill-/unknown species through timely conservation action. This is particularly relevant when the species are neither iconic nor flagships, therefore lessening the potential for accessing conservation means, such as in the case of the mygalomorph spider Macrothele calpeiana. The species is endemic to southern Iberia but its distribution and ecology is barely documented in Portugal. Therefore, we made a comprehensive survey throughout its estimated range in the south of the country. The species is spread unevenly and patchily throughout low mountainous terrain in south/southwest Portugal, preferably along shale/ greywacke/clay roadside banks. It seems rare in the surrounding limestone area to the south and absent from the peneplain to the north. The webs were found in groups averaging 10.0±15.2 webs/site and predominantly orientated to the northern quadrants (68.1%), possibly to compensate for higher summer temperatures. Yet, this trend showed a reverse tendency in the north of the range, suggesting a possible temperature moderating effect of the nearby Atlantic ocean. The surrounding vegetation is largely dominated by cork oak forest, tall strawberry tree/ heather thicket, or open cork/holm oak woodland. Other vegetation types are low scrub, pine or eucalypt stands in smaller proportions. M. calpeiana seems constrained by specific microhabitat and microclimatic conditions, suggesting that it may be at risk from climate change and habitat disturbance.

Luís Palma, Ana Filipa Palmeirim "Insights into the distribution and ecology of the funnelweb spider Macrothele calpeiana in Portugal," Arachnology, 20(5), 659-669, (8 July 2026)