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| Adhaerobufo gen. nov. Adhaerobufo ceratophrys (Boulenger, 1882) comb. nov., Adhaerobufo nasicus (Werner, 1903) comb. nov. in Dias, Phillips, Pereyra, Means, Haas et Kok, 2024. Photos by D. Bruce Means and Pedro H. Dias |
Abstract
Tadpoles serve as crucial evidence for testing systematic and taxonomic hypotheses. Suctorial tadpoles collected in Guyana were initially assigned to Rhaebo nasicus through molecular phylogeny. Subsequent analysis of larval and adult morphological traits revealed synapomorphies within the clade encompassing R. nasicus and R. ceratophrys, prompting the recognition of a new genus described herein as Adhaerobufo. The new genus is distinguished from other bufonids by specific phenotypic traits including an enlarged, suctorial oral disc with distinct papillae arrangements, and the presence of certain muscles and narial vacuities at the larval stage. However, only a few adult external characteristics (e.g., enlarged eyelids, infraocular cream spot), seem to be reliably discriminative from related genera. This study underscores the significance of larval morphology in anuran systematics and offers new insights into the evolution of suctorial and gastromyzophorous larvae within bufonids.
Keywords: Evolution, Larval traits, Musculoskeletal system, Pantepui, Suctoriality, Systematics, Taxonomy
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| Living tadpole of “Rhaebo” nasicus in right lateral (A), dorsal (B), and ventral (C) views. Photos by D. Bruce Means |
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| The tadpole of “Rhaebo” nasicus (CPI10704) at stage 38 in lateral (A), dorsal (B), and ventral (C) views. Scale bar = 1.0 mm. Photos by Pedro H. Dias |
Adhaerobufo gen. nov.
Type species: Bufo nasicus (Werner, 1903) comb. nov.
Content: Adhaerobufo ceratophrys (Boulenger, 1882) comb. nov., and Adhaerobufo nasicus (Werner, 1903) comb. nov.
Etymology: Adhaerobufo gen. nov. (gender masculine) is derived from the Latin adhaerens, meaning adherent and the Latin būfo, meaning toad. The name refers to the unique suctorial morphology of their tadpoles.
Definition and diagnosis:
Adhaerobufo gen. nov. can be differentiated from all other Bufonidae by the combination of the following characters: (1) tadpole with enlarged, suctorial, oral disc; (2) tadpole oral disc with a complete row of marginal papillae; (3) tadpole oral disc with multiple rows of submarginal papillae on the lower lip and by a single row of marginal papillae on the upper lip; (4) tadpole oral disc with an uninterrupted second anterior row of keratodonts; (5) presence of the m. interhyoideus posterior at larval stage; (6) presence of the m. rectus abdominis anterior at larval stage; (7) presence of narial vacuities in the buccopharyngeal cavity at larval stage; (8) projecting, enlarged eyelid in adults; (9) presence of an infraocular cream spot in adults, (10) sphenethmoid relatively narrow, overlapping only the medial ends of the palatines; and (11) posterior process of the prootic prominent and notched.
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| Kamana Creek, upstream within 100 m of Kamana Waterfall, draining Mt. Kopinang low waters where tadpoles of Adhaerobufo were collected (A) and an unnamed stream on the slopes of Maringma-tepui where tadpoles were also observed (B). Amplexing couple of A. nasicus (C and D). Photos by D. Bruce Means (A, C, D) and Philippe J. R. Kok (B) |
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| Geographical distribution of Adhaerobufo gen. nov. in northwestern Guyana, eastern Venezuela and upper Amazon Basin. Inset map of South America, highlighting the geographical area occupied by the genus (A). Known distribution of A. ceratophrys and A. nasicus (B). Examples of macrohabitats in which the new genus is present; Kaieteur Falls in Guyana (C), uplands and highlands of western Guyana (D), and lowlands, Amazon Forest, Icá River, Brazil (E). Shape files of the geographical distribution were downloaded from the IUCN website. Adult and tadpole are from A. nasicus. Photos by: Philippe Kok (C and D) and Pedro H. Dias (E) |
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| Torrential environments that were colonized by suctorial/gastromyzophorous larvae of bufonids. Adult of Atelopus sp. in Tacarcuna, Colombia (A); fast flowing waters occupied by Atelopus elegans at Isla Gorgona, Colombia (B); larvae of Ansonia guibei attached to rocks of fast flowing streams in Borneo (C and D). Photos by Marco A. Rada (A), David Velázquez (B), and Alexander Haas (C and D) |
Pedro Henrique dos Santos Dias, Jackson R. Phillips, Martín O. Pereyra, D. Bruce Means, Alexander Haas and Philippe J. R. Kok. 2024. The Remarkable Larval Morphology of Rhaebo nasicus (Werner, 1903) (Amphibia: Anura: Bufonidae) with the Erection of A New bufonid Genus and insights into the Evolution of Suctorial Tadpoles. Zoological Letters. 10: 17. DOI: doi.org/10.1186/s40851-024-00241-0
