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

Posted by
  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...

A new species of Mundochthonius Chamberlin, 1929 (Pseudoscorpiones, Chthoniidae) from Tsushima Island, Japan with notes on cryptic diversity and biogeography of the Japanese Archipelago

Posted by

 


A new species of Mundochthonius Chamberlin, 1929 (Pseudoscorpiones, Chthoniidae) from Tsushima Island, Japan with notes on cryptic diversity and biogeography of the Japanese Archipelago

Abstract

Species of the pseudoscorpion genus Mundochthonius (Chthoniidae) are difficult to distinguish using traditional morphology, as diagnostic traits exhibit limited variation despite substantial genetic divergence. Here, we used publicly available sequence data to reconstruct the phylogeny of Japanese Mundochthonius and applied multiple species-delimitation methods to assess diversity and biogeographic patterns. Phylogenetic analyses recovered seven major genetic clades consistent with previous studies, while five delimitation approaches indicated substantially higher species diversity than currently recognized. These clades exhibit strong geographic structuring: clades 1, 3, 5, 6, and 7 are restricted to eastern Japan, whereas clade 4 is broadly distributed in western Japan, a pattern corresponding to the Itoigawa-Shizuoka Tectonic Line, which demarcates the western boundary of the Fossa Magna region. We describe Mundochthonius tsushimaensis sp. nov., a genetically distinct lineage endemic to Tsushima Island, which is situated between the Korean peninsula and Kyushu island of the Japanese Archipelago. Although the new species lacks clear morphological differentiation from other members of the clade, it displays a COI p-distance of 14% from all congeners, indicating substantial genetic divergence that is further corroborated by the geographical isolation of the island. Additionally, we elevate Mundochthonius japonicus scolytidis to species rank (Mundochthonius scolytidis stat. nov.) based on genetic distinctiveness. We propose that the phylogeographic structure of Japanese Mundochthonius reflects a refugial model, where deeply divergent, range-restricted eastern clades originated on the complex geological history of the Japanese Archipelago. These findings underscore the importance of integrating molecular and biogeographic data for resolving taxonomy in morphologically conserved groups.

Jeong K-H, Oh J, Shida R, Johnson J, Harms D, Kim S (2026) A new species of Mundochthonius Chamberlin, 1929 (Pseudoscorpiones, Chthoniidae) from Tsushima Island, Japan with notes on cryptic diversity and biogeography of the Japanese Archipelago. Evolutionary Systematics 10(2): 263-274. https://doi.org/10.3897/evolsyst.10.199765