The Tadpole and Karyotype of Rhinella achavali (Anura: Bufonidae)
We describe the external morphology, buccal cavity, chondrocranium, hyobranchial skeleton, and musculature of the tadpole of Rhinella achavali (Achaval's Toad), along with its karyotype. Tadpoles were found in a small, permanent stream and were showing schooling behavior. The characterization of the proposed species groups within Rhinella cannot be currently improved using external larval morphology, as it seems to be much conserved within this genus. Buccal cavity morphology confirms the distinctiveness of the Rhinella veraguensis (Veragua Toad) group with respect to other known Rhinella. Musculoskeletal character states are similar among bufonids, although within this family the basal genus Melanophryniscus shows some distinctive states. The karyotype is composed of 22 bi-armed chromosomes, with secondary constrictions in pair 7, as found in the other species in the Rhinella marina (Marine Toad) group.Abstract
Tadpole of Rhinella achavali at stage 31 (MNHN 9470). Lateral view (A), dorsal view (B), and oral disc (C). Scale = 5 mm (A,B) and 1 mm (C).
Buccal cavity of Rhinella achavali tadpole at stage 33. Buccal roof (A), buccal floor (B), and details of labial teeth (C), choanae (D), and noncolored spurs (E). Scale = 1 mm (A,B) and 10 μm (C,D,E).
Chondrocranium and hyobranchial skeleton of Rhinella achavali tadpole at stage 31. Chondrocranium, dorsal view (A), suprarostral, frontal view (B), lower jaw, frontal view (C), and hyobranchial skeleton, ventral view (D). Scale = 1 mm.
Cranial muscles of Rhinella achavali tadpole at stage 33. Dorsal (A) and ventral view (B). References: cbII–IV, constrictor branchialis II–IV; db, diaphragmatobranchialis; gh, geniohyoideus; ha, hyoangularis; ih, interhyoideus; im, intermandibularis; labI–IV, levator arcuum branchialium I–IV; lma, levator mandibulae articularis; lmep, levator mandibulae externus profundus; lmes, levator mandibulae externus superficialis; lmi, levator mandibulae internus; lml, levator mandibulae lateralis; lmlp, levator mandibulae longus profundus; lmls, levator mandibulae longus superficialis; ml, mandibulolabialis; oh, orbitohyoideus; qa, quadratoangularis; rc, rectus cervicis; sa, suspensorioangularis; sh, suspensoriohyoideus; so, subarcualis obliquus; srI–IV, subarcualis rectus I–IV; tp, tympanopharyngeus. Scale = 1 mm.
Chromosomes of Rhinella achavali. Giemsa-stained karyotype (A), C-banded karyotype (B), and Ag-NOR in chromosome pair 7 (inset). Scale = 10 μm.
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