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...

Description of the male of Kaira candidissima with notes on its natural history (Araneae: Araneidae)

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Description of the male of Kaira candidissima with notes on its natural history (Araneae: Araneidae)

Abstract

Kaira Pickard-Cambridge, 1889 is a genus of Neotropical spiders that currently includes seventeen species, eight of which are known only from females. These araneids do not make orbicular webs to catch prey but use pheromone-like substances to attract male moths. In this work, the male of K. candidissima (Mello-Leitão, 1941) is described for the first time and individuals of K. gibberosa O. Pickard-Cambridge, 1890 are recorded, based on specimens from La Pampa, Argentina. The first scanning electron micrographs of male palps of the genus are provided for both species along with illustrations of the unknown male of K. candidissima. The males of K. candidissima can be differentiated from others of the genus by the shape of opisthosoma which is white and has one anterior hump and two lateral tubercles. Kaira candidissima becomes active at dusk and presumably remains so throughout the night. Active individuals were observed hanging from trapezoidal webs extending 1–2 cm from grass leaves, 35-65 cm above the ground, with legs I and II extended. Concentrations of tangled threads can be seen located in the lines of the trapezoidal webs. A juvenile female was observed capturing and consuming a male Cecidomyiidae (Diptera: Nematocera) and an adult female was observed feeding on a lepidopteran. The distribution of these species extends from north-eastern Argentina to north-east of La Pampa province, in central Argentina, representing the southernmost record for the genus.

Peralta-Seen, N., Esquivel, C.A., Blas, G.S. & Diez, F. (2026) Description of the male of Kaira candidissima with notes on its natural history (Araneae: Araneidae). Zootaxa, 5862 (2), 333–346. https://doi.org/10.11646/zootaxa.5862.2.7