A New Highly Modified Species of Creagrutus (Characidae: Stevardiinae) Apparently Mimetic of Prodontocharax
A new species of Creagrutus of the subfamily Stevardiinae is described from the Río Cachiyacu, a tributary of the Río Huallaga in Peruvian Amazon. The species demonstrates a number of pronounced differences from the typical species of Creagrutus, most notably: the ventrally displaced jaws, the compressed, spatulate dentition and anterior portion of the neurocranium, along with modifications of the digestive system and the swimbladder. Its assignment to the genus is, nonetheless, supported by both morphological and molecular evidence. The new species is apparently mimetic of Prodontocharax melanotus, which also occurs at its type-locality.
Holotype of Creagrutus cerritulus, new species, MUSM 54501 (ex-MHNG 2725.023), 41.6 mm SL; Río Cachiyacu, tributary of Río Huallaga, 520 m elevation, 8°17′37″S, 76°21′05″W; lateral view. Scale bar = 10 mm.
Creagrutus cerritulus, MPEG 32941, 46.0 mm SL, lateral view of the right side of upper and lower jaws and dentition. Anterior to right. Scale bar = 1 mm.
Creagrutus cerritulus, MPEG 32941, 46.0 mm SL, lingual view of the premaxillae and detailed view of the unusual, strongly interdigitate joint between premaxillary bones. White scale bar = 1 mm; black scale bar = 0.2 mm.
Creagrutus cerritulus, MPEG 32941, 46.0 mm SL CS. (A) X-ray image of specimen prior to preparation; (B) schematic representation of the digestive tract (intestine length approx. 112.5 mm); (C) schematic representation of the swimbladder in dorsal view, anterior to left. Scale bar = 5 mm.
Prodontocharax melanotus, holotype, CAS 59793, 43.1 mm SL, a syntopic species sharing a high similarity with Creagrutus cerritulus. Scale bar = 10 mm. © California Academy of Sciences, Department of Ichthyology.
Contributor Notes
Associate Editor: R. E. Reis.