Tuesday, April 27, 2021

[Herpetology • 2021] Night Stalkers from Above: A Monograph of Toxicodryas Tree Snakes (Squamata: Colubridae) with Descriptions of Two New Cryptic Species from Central Africa


Toxicodryas adamanteus  

in Greenbaum, Allen, Vaughan, ... et Brown, 2021. 
 
Abstract
The genus Toxicodryas, historically included with the renowned Australasian cat-eyed snakes of the colubrid genus Boiga, currently includes two widespread species (T. blandingii and T. pulverulenta) in western, central, and eastern Africa. We leverage findings from a recent phylogenomic and historical demographic analysis of this genus (based on 2848–4471 Rad-seq loci from across the genome), with robust sampling from throughout the ranges of both species, to define two additional taxonomic units, with species boundaries corresponding to river barriers. Additional morphometric data from scores of examined museum specimens and literature records bolster the recognition of these two new cryptic species. We hypothesize that T. blandingii occurs west of the confluence of the Congo and Ubangi rivers, whereas a cryptic new species that is found east of this biogeographic barrier has significantly higher numbers of ventral scale counts in both sexes, additional significant differences in several scale counts, and lower venom toxicity. Toxicodryas pulverulenta occurs west of the Niger Delta in West Africa, whereas a cryptic new species that is found east of this biogeographic barrier has significantly higher numbers of subcaudal scale counts in both sexes. A review of published information regarding morphological variation, ecology, natural history, habitat, and venom is summarized for these four Toxicodryas species.

Keywords: Reptilia, Congo Basin, arboreal, cryptic species, rivers, taxonomy


Toxicodryas adamanteus sp. nov. in life.
 adult female (UTEP 22205) from Salonga National Park, Democratic Republic of the Congo.
Photo: E. Greenbaum

Toxicodryas adamanteus sp. nov.

Etymology. The specific epithet adamanteus is a Latin adjective referring to the diamond-shaped marks on the flanks and dorsum of this species.

Toxicodryas vexator sp. nov. (field no. CRT 3890) from Kona, Democratic Republic of the Congo (DRC), showing everted hemipenis in ventrolateral view.
Photo: Z. Nagy

Toxicodryas vexator sp. nov.

Etymology. The specific epithet is a noun in apposition, invariable, from the Latin noun vexator, meaning harasser or stalker, in reference to the fact that this snake stalks prey when they are sleeping, and to its aggressiveness when disturbed.


Eli Greenbaum, Kaitlin E. Allen, Eugene R. Vaughan, Olivier S. G. Pauwels, Van Wallach, Chifundera Kusamba, Wandege M. Muninga, Mwenebatu M. Aristote, Franck M. M. Mali, Gabriel Badjedjea, Johannes Penner, Mark-Oliver Rödel, Jacqueline Rivera, Viktoria Sterkhova, Grant Johnson, Walter P. Tapondjou N. and Rafe M. Brown. 2021. Night Stalkers from Above: A Monograph of Toxicodryas Tree Snakes (Squamata: Colubridae) with Descriptions of Two New Cryptic Species from Central Africa. Zootaxa. 4965(1); 1–44. DOI: 10.11646/zootaxa.4965.1.1