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| Siagonodon exiguum Martins, Folly, Ferreira, Garcia da Silva, Koch, Fouquet, Machado, Lopes, Pinto, Rodrigues & Passos, 2023 DOI: 10.3897/vz.73.e98170 |
Abstract
Threadsnakes are known for their conserved external morphology and historically controversial systematics, challenging taxonomic, biogeographic and evolutionary researches in these fields. Recent morphological studies—mostly based on µCT data of the skull and lower jaw—have resolved systematic issues within the group, for instance leading to the description of new taxa or re-positioning little-known scolecophidian taxa in the tree of life. Herein we describe a new polymorphic species of the genus Siagonodon from Amazonia based on morphological (external, osteology and hemipenis) and molecular data, and provide the first hemipenial description for the genus. We also reassign Siagonodon acutirostris to the genus Trilepida based on osteological data in combination with molecular evidence. The new species described represents an evolutionary paradox for scolecophidians because the species displays a remarkable variation in the shape of the snout region that is otherwise always highly conserved in this clade. Finally, this study reinforces the importance of protected areas as essential in maintaining vertebrate populations, including those that are not yet formally described.
Keywords: Hemipenial morphology, intraspecific variation, Neotropics, osteology, phylogeny, polymorphism, Squamata
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| Comparisons of the head in dorsal (left column), lateral (middle column) and ventral (right column) views of the type series of Siagonodon exiguum sp. nov. A MNHN-RA-2023.0001; B MNRJ 27557; C MNRJ 27558; D MNRJ 27559; E MNRJ 27560; F MNRJ 27561; G MNRJ 27562 (holotype). |
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| Siagonodon exiguum sp. nov. Dorsal (A, D), lateral (B, E), and ventral (C, F) views of the holotype (MNRJ 27562; Figs A–C) and paratype (MNHN-RA-2023.0001; D–F). |
Siagonodon exiguum sp. nov.
Diagnosis: The putative autapomorphy of Siagonodon exiguum sp. nov. may be represented by lateral pointed projections on the snout or with inconspicuous lateral projection by presenting a slight concavity on the mid-rostral portion of snout (see below in comparison the opposite states for snout condition).
Etymology: The specific epithet exiguum is a Latin word meaning little, short, scanty and/or poor. Although readers might think that the name was chosen in allusion to the small size of the species, we dedicate the species to all minorities in science including gender, race/color, ethnicity, and sexual orientation that are considerably underrepresented in the academia throughout the world, especially in higher positions. Although several worldwide initiatives have been implemented in the past few years, the scientific environment is still biased, discouraging and, sometimes noxious, largely because of persisting systemic social, economic and cultural aspects.
Angele Martins, Manuella Folly, Guilherme Nunes Ferreira, Antônio Samuel Garcia da Silva, Claudia Koch, Antoine Fouquet, Alessandra Machado, Ricardo Tadeu Lopes, Roberta Pinto, Miguel Trefaut Rodrigues and Paulo Passos. 2023. An Evolutionary Paradox on Threadsnakes: Phenotypic and Molecular Evidence reveal A New and Remarkably Polymorphic Species of Siagonodon (Serpentes: Leptotyphlopidae: Epictinae) from Amazonia. Vertebrate Zoology. 73: 345-366. DOI: 10.3897/vz.73.e98170
