Meeting Abstract
Callichthyid catfishes produce sounds by pectoral spine stridulation in agonism and reproduction. Vocal ridge shape can be acute and rounded within individuals for the subfamily Corydoradinae and is similar across species. Dorsal process ridge width and inter-ridge distance is similar across species. To determine whether species’ mechanisms are convergent or have diverged we counted dorsal process ridge number for adult specimens (17 species, four genera) using scanning electron and dissecting microscopes. Scleromystax ridges ranged 34 to 45 (39 + 4 SD, n = 6 individuals). Aspidoras ridges ranged 19 to 44 (36 + 9, n = 6). Brochis ridges ranged 59 to 81 (68 + 8, n = 6). Corydoras pooled species ridges ranged 38 to 76 (55 + 9, n = 70). Ridge number correlated with body size (SL) for Corydoras species pooled (r2 = 0.2293, p <0.00002). Total ridges per species for 14 Corydoras species (n = 4 to 9 individuals/species) positively correlated with body size (SL) for three species (r2 = 0.6834 to 0.9772, p<0.04 to 0.001). Specimen standard length was similar (4.0 cm + 0.8 SD, 2.3 – 7.5 cm, n = 89). The presence of vocal ridges in all specimens suggests that both sexes could vocalize. Correlation of ridge number with body size for some species and the similarity in adult size for many species in the Corydoradinae suggests that if species differ in vocal communication signals this would have to be accomplished by variation in vocal muscles, their origins or insertions and neural control.
