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...

Mygalomorph spiders from Peru (Araneae, Pycnothelidae, Rhytidicolidae): description of two new species and first Peruvian record of the family Rhytidicolidae

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Mygalomorph spiders from Peru (Araneae, Pycnothelidae, Rhytidicolidae): description of two new species and first Peruvian record of the family Rhytidicolidae

Abstract

Two previously unknown mygalomorph spider species belonging to two families are described from the south-central Andean region of Peru. Within the family Pycnothelidae, Acanthogonatus goloboffi sp. n. is described, diagnosed and illustrated based on a female from Ccochirhuay, Cusco. The female of this species differs from most known Acanthogonatus by the shape of the spermathecae, which possess two single receptacles lacking additional projections or chambers. It further differs from congeners sharing a single receptacle by having non-spiraled ducts with a well-defined constriction and outwardly directed spherical receptacles. This represents the second record of the genus Acanthogonatus in Peru. Within the family Rhytidicolidae, Fufius agualaniensis sp. n. is described, diagnosed and illustrated based on a female from Agualani, Puno. The female of this species is distinguished from congeners by the following combination of characters: a straight fovea; a sternum as wide as long; a labiosternal junction with a well-developed septum; a preening comb on metatarsus IV consisting of seven large spines in a single row; and spermathecae with a wide, inwardly curved stalk giving rise to three sinuous branches ending in digitiform or domed structures. This constitutes the first formal record of the family Rhytidicolidae from Peru.

Beratz, M. J., Ferretti, N. E., Chaparro, J. C., & West, R. C. (2026). Mygalomorph spiders from Peru (Araneae, Pycnothelidae, Rhytidicolidae): description of two new species and first Peruvian record of the family Rhytidicolidae. Zoodiversity, 60(2). https://doi.org/10.15407/zoo2026.02.109