RESUMO
The family Pseudopimelodidae is widely distributed in South America and includes 51 described species organized in seven genera. Only two of four species of the genus Pseudopimelodus have been recorded for the trans-Andean basins of Colombia, Pseudopimelodus bufonius and P. schultzi, whose similarity in external morphology make their identification difficult. We performed a phylogenetic analysis using a fragment of the Cytochrome C Oxidase subunit 1 gene (COI), and analyzed osteological and traditional morphometric characters to study Pseudopimelodus from the Colombian trans-Andean region. Results provided strong support for two clades phylogenetically related to Pseudopimelodus, that showed clear-cut molecular, osteological, and morphometric differences from previously described bumblebee catfishes. Based on these results, we describe two Pseudopimelodus species from the Magdalena-Cauca River Basin: P. magnus sp. nov. with 43-44 vertebrae, dorsal-fin spine with serrations on its anterior margin; lateral margin of transverse process of the fourth vertebra of the Weberian complex forming an acute angle in ventral view and P. atricaudus sp. nov. with 39 vertebrae, dorsal-fin spine smooth on its anterior margin and a dark, vertical band covering 3/4 of the caudal fin with base of rays and tip of caudal-fin lobes hyaline.
RESUMO
Objective. To study the trophic ecology of Saccodon dariensis in the Peñoles and El Cardal streams, Guatape River mid-basin, Magdalena River Basin, Colombia. Materials and methods. To compare differences in size between individuals from the two streams in terms of hydrologic periods, oral polymorphisms or sexes, an analysis of variance was conducted (ANOVA). Volume percentages, frequency of occurrence and the food importance index (FII) were determined; a principal component analysis (PCA) and an ANOVA was carried out to determine the diet differences between streams, climatic periods, oral polymorphism, sexes and developmental states, as well as a Mann-Whitney pairwise comparison test for each food category. Results. A significant difference was found in size between individuals of the two streams with different oral polymorphism. Algae are the most important food item (FII: 91.9%), followed by Trichoptera and insect remains (FII: 4.3%), and vegetal material (FII: 1.8%). The PCA did not indicate significant differences in diet between streams, climatic periods, oral polymorphisms, sexes or developmental states, but the ANOVA and Mann-Whitney pairwise comparison test indicated differences in oral morphotype, where individuals with a straight mouth consumed more vegetal material. We also observed different proportions in consumption of different algae genera, and increased consumption of insects in ontogeny, this being higher in individuals with a straight mouth. Conclusions. The species is algaevorous. The oral morphotypes of S. dariensis may be related to a trophic polymorphism that confers different trophic habits and differential access to the items that constitute their diet.
Objetivo. Estudiar la ecología trófica de Saccodon dariensis en las quebradas Peñoles y El Cardal, parte media del río Guatape, cuenca del rio Magdalena, Colombia. Materiales y métodos. Para contrastar diferencias entre individuos de las dos quebradas en cuanto a períodos hidrológicos, polimorfismos bucales y sexos se realizó un análisis de varianza (ANOVA). Se determinó los porcentajes de volumen, frecuencia de ocurrencia e índice de importancia alimentaria (IIA); se realizó un análisis de componentes principales (ACP) y un ANOVA para determinar diferencias de dieta entre quebradas, períodos climáticos, polimorfismos bucales, sexos, estados de desarrollo, y una prueba de comparación por pares de Mann-Whitney para cada categoría de alimento. Resultados. Se encontró diferencia significativa en la talla entre individuos de las dos quebradas con diferente morfotipo bucal. Las algas es el ítem de alimento más importante (IIA: 91.9%), seguido por Trichoptera y restos de insectos con (IIA: 4.3%) y material vegetal (IIA: 1.8%). El ACP no indicó diferencias en la alimentación entre quebradas, períodos climáticos, polimorfismo bucal, sexos o estados de desarrollo, pero la ANOVA y la prueba de Mann-Whitney indicaron diferencias por morfotipo bucal, donde individuos de boca recta consumen más material vegetal. Se observó en proporciones diferentes el consumo de diferentes géneros de algas, y aumento de consumo de insectos en ontogenia, siendo más alto para individuos de boca recta. Conclusiones. La especie es alguivora. Los morfotipos bucales en S. dariensis pueden estar relacionados con un polimorfismo trófico que le confiere diferentes hábitos tróficos y acceso diferencial a los ítems que constituyen su dieta.