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| Micrelapidae fam. nov., Das, Greenbaum, Meiri, Bauer, Burbrink, ... et Merilä, 2023. |
Highlights:
• More than 4500 ultraconserved elements loci resolved the phylogeny of the snake superfamily Elapoidea.
• Anatomical data and phylogeny supported establishment of a new Afro-Asian family of snakes, Micrelapidae.
• Different phylogeny estimation methods inferred largely congruent topologies.
• Time calibrated phylogeny supported the hypothesis of a rapid elapoid radiation in the Eocene.
Abstract
The highly diverse snake superfamily Elapoidea is considered to be a classic example of ancient, rapid radiation. Such radiations are challenging to fully resolve phylogenetically, with the highly diverse Elapoidea a case in point. Previous attempts at inferring a phylogeny of elapoids produced highly incongruent estimates of their evolutionary relationships, often with very low statistical support. We sought to resolve this situation by sequencing over 4,500 ultraconserved element loci from multiple representatives of every elapoid family/subfamily level taxon and inferring their phylogenetic relationships with multiple methods. Concatenation and multispecies coalescent based species trees yielded largely congruent and well-supported topologies. Hypotheses of a hard polytomy were not retained for any deep branches. Our phylogenies recovered Cyclocoridae and Elapidae as diverging early within Elapoidea. The Afro-Malagasy radiation of elapoid snakes, classified as multiple subfamilies of an inclusive Lamprophiidae by some earlier authors, was found to be monophyletic in all analyses. The genus Micrelaps was consistently recovered as sister to Lamprophiidae. We establish a new family, Micrelapidae fam. nov., for Micrelaps and assign Brachyophis to this family based on cranial osteological synapomorphy. We estimate that Elapoidea originated in the early Eocene and rapidly diversified into all the major lineages during this epoch. Ecological opportunities presented by the post-Cretaceous-Paleogene mass extinction event may have promoted the explosive radiation of elapoid snakes.
Keywords: Elapoidea, Micrelapidae fam. nov., phylogeny, ultraconserved elements, UCE
Micrelapidae new family
Type genus: Micrelaps Boettger, 1880
Type species: Micrelaps muelleri Boettger, 1880
Etymology: Boettger (Böttger) did not give the etymology for the generic nomen but was almost certainly from the Latin adjective micro-, derived from the Greek mikros (small), and elaps, the Latinised form of the Greek noun éllops or élaps (literally sea-fish or serpent, but here in reference to the snake genus Elaps, now a synonym of Homoroselaps). Micrelapidae fam. nov. is derived from Micrelaps by the taking the stem elap- of the root word of the nomen.
Content: Micrelaps muelleri Boettger, 1880, Micrelaps bicoloratus Sternfeld, 1908, Micrelaps vaillanti Mocquard, 1888, Brachyophis revoili Mocquard, 1888.
Diagnosis and definition: In the crania of Micrelaps and Brachyophis we examined the ectopterygoid was laterally and medially expanded at the point of contact with the pterygoid, with this expansion not being contiguous with the ectopterygoid anterolateral and anteromedial lobes (Fig. 4, Supplementary material fig. 53, 54). The lateral expansion is a posterolaterally and somewhat ventrally directed, very prominent protuberance continuous with a ridge on the ventral surface of the pterygoid. This character state was not present in any other cranium we examined and is very likely a synapomorphy of the family.
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Distribution: Micrelaps spp. is distributed in eastern and north-eastern Africa and western Asia. Brachyophis is limited to Somalia in north-eastern Africa.
Sunandan Das, Eli Greenbaum, Shai Meiri, Aaron M. Bauer, Frank T. Burbrink, Christopher J. Raxworthy, Jeffrey L. Weinell, Rafe M. Brown, Jonathan Brecko, Olivier S.G. Pauwels, Nirhy Rabibisoa, Achille P. Raselimanana and Juha Merilä. 2023. Ultraconserved Elements-based Phylogenomic Systematics of the Snake Superfamily Elapoidea, with the Description of A New Afro-Asian Family. Molecular Phylogenetics and Evolution. In Press, 107700. DOI: 10.1016/j.ympev.2022.107700
