An Overlooked Species of Enigmatic Wolf Spider (Araneae: Lycosidae) Clarifies the Mysterious Distribution of its Sibling

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  An Overlooked Species of Enigmatic Wolf Spider (Araneae: Lycosidae) Clarifies the Mysterious Distribution of its Sibling Abstract Several wolf spiders exhibit a peculiar geographical distribution. One good example of this is Pardosa aenigmatica Tongiorgi, 1966, recently recognized in Italy and the Middle East but missing in the Balkans. A comparison of populations from the disjunctive areas revealed that they would be better described as two distinct species. As a result, here we describe Pardosa sepidehae sp. nov. The paper includes detailed descriptions and comparative illustrations of male and female copulatory organs for the newly discovered species and P. aenigmatica. Pardosa sepidehae sp. nov. is distributed in the Middle East, whereas P. aenigmatica remains endemic to the Apennine Peninsula. Adile Akpinar, Petr Dolejš "An Overlooked Species of Enigmatic Wolf Spider (Araneae: Lycosidae) Clarifies the Mysterious Distribution of its Sibling," Annales Zoologici, 76(29), ...

Paralysis Efficiency (PD50) Scales Linearly with Lethality (LD50) in Spider Venoms

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Paralysis Efficiency (PD50) Scales Linearly with Lethality (LD50) in Spider Venoms

Abstract

Historically, venom potencies have been assessed using measures of lethality, such as the median lethal dose (LD50). However, venoms may be selected primarily for their ability to rapidly incapacitate rather than cause mortality, meaning LD50 may not capture the efficacy of venoms in an ecological and evolutionary context. To capture this context, recent studies have adapted measures that assess venoms’ ability to rapidly incapacitate, such as the median paralysis dose (PD50). However, while PD50 values are expected to provide a more proximate assessment of ecological variation in venom potency, it is unknown whether historically available LD50 values are still useful proxies of ecologically relevant potency or whether they capture independent axes of venom variation. Here, we test the relationship between LD50 and PD50 in spider venoms by experimentally estimating LD50 and PD50 for 12 species and collating additional potency data for 46 species retrieved from the literature, producing a dataset of 55 species spanning 26 families when combined. We observed a linear isometric relationship between LD50 and PD50, showing these potency measures are both strongly correlated, with an increase in paralysis efficiency associated with a similar increase in lethality. Our results suggest that due to the correlation between functional aspects of venom potency, paralysis and lethality, historically available LD50 values may be used to compare general venom potencies in spiders, provided that they are based on the same prey model.
Lyons, K., Leonard, D., McSharry, L., Martindale, M., Collier, B. L., Vitkauskaite, A., Dunbar, J. P., Dugon, M. M., & Healy, K. (2026). Paralysis Efficiency (PD50) Scales Linearly with Lethality (LD50) in Spider Venoms. Toxicon: X, 100256. https://doi.org/10.1016/j.toxcx.2026.100256