The genus Pseudoplatystoma Bleeker consists of three species long recognized as: P. fasciatum (Linnaeus), P. tigrinum (Valenciennes), and P. corruscans (Spix & Agassiz), and five species recently recognized or described here: P. punctifer (Castelnau), P. reticulatum Eigenmann & Eigenmann, P. orinocoense n. sp., P. metaense n. sp., and P. magdaleniatum n. sp. The eight species form a monophyletic group with two clades that are supported by anatomical features (i.e., skeletal anatomy and myology). One clade (P. tigrinum and P. metaense) is restricted to the Orinoco and Amazon basins, and the other clade, comprised of the remaining six species, is found in the Guyanas, Orinoco, Amazon, and Paraná basins. The species are diagnosed on the basis of body shape, color pattern (e.g., bars, loops, and spots), skeletal anatomy, and vertebral numbers. Pseudoplatystoma punctifer and P. tigrinum) are sympatric in the Amazon Basin, P. metaense and P. orinocoense in the Orinoco Basin, and P. corruscans and P. reticulatum, are sympatric in the Paraná. Pseudoplatystoma magdaleniatum (Magdalena basin) and P. fasciatum (Guyanas) each occur as the only species of Pseudoplatystoma in their respective individual ranges. Pseudoplatystoma reticulatum may be sympatric with the two other species in the Amazon Basin, but we have no records of them being captured together in the mainstream or tributaries. All eight species are used as food in both commercial and subsistence fishing, and there is a moderate–sized ornamental fish market for the young and juveniles. A key to adults of the eight species is included.

Two types of odontodes, or dermal teeth, occur in the neotropical Andean astroblepid catfishes. Both odontode types conform in structure to dermal teeth of gnathostomes in having dentine surrounding a central pulp cavity covered by a superficial layer of enameloid, but differ from one another in terms of attachment and association with other epidermis features. Type I odontodes in astroblepids, also found in all representatives of the superfamily Loricarioidea, are larger (40-50 microm base diameter), generally conical and sharply pointed, occur on the fin rays, and are associated with dermal bone. Type I odontodes attach to an elevated pediment of dermal bone of the fin lepidotrich, and to dermal bone generally in loricarioids, via a ring of connective tissue. Type II odontodes of astroblepids are smaller (15-20 microm base diameter) and blunt, occur in the skin of the head, maxillary barbels, nasal flap, and lip margins, and are not associated with dermal bone. Observations based on histology and scanning electron microscopy indicate that Type II odontodes are associated with other epithelial structures to form a putative mechanosensory organ. The odontode base lies deep in the dermis. The shaft is surrounded by a dense patch of microvillous epithelium and projects from within a pit formed by an elevated ring of laminar epithelial cells bearing several columnar, knob-like putative mechanosensory structures. Type II odontode organs have thus far been observed in only three astroblepid species, Astroblepus longifilis, A. chotae, A. rosei, where they occur in especially dense arrays on the maxillary barbels, surrounded by discrete patches of microvilli and separate mechanoreceptors. Type II odontode organs are less dense elsewhere on the body, but also occur in the skin of the snout, head, and lips. Typical taste buds are absent from the barbels of these species, but present in other astroblepids. The presence of Type II odontodes and their association with specialized epithelial pit organs are unique to astroblepids among siluriforms and may be potentially important adaptations to life in torrential mountain streams.

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Astroblepid species inhabit the Andean Cordilleras in South America. Their habitat has undergone a rapid transformation to the unimaginable levels of degradation since ancient times. State of knowledge on the habitat perturbation and the concomitant extirpation of endemic astroblepid species is scarce. The Andes Cordilleras are characterized by fertile soil and as a result of that, vast regions are transformed for agriculture and pasture for cattle. These processes require the use of water obtained from creeks and springs that causes remarkable changes of the natural configuration of these water systems and the disappearance of the fish fauna together with the zooplankton and aquatic flora. Despite these human actions, some species of Astroblepus may have the ability to respond to the rapid habitat transformation enabling them to survive. In this paper we will discuss the incidence of habitat perturbation in a localized stream segment on the presence of Astroblepus mariae. Key words: Habitat perturbation, survival, refuge, buffer zone. Perturbación de hábitat y estrategias de supervivencia del bagre Astroblepus mariae (Fowler, 1919) ResumenLas especies del género Astroblepus habitan en la cordillera de los Andes en Suramérica. Desde tiempos remotos sus hábitats han sufrido transformaciones rápidas que han resultado en niveles inimaginables de degradación. Sin embargo, es escaso el conocimiento sobre las perturbaciones de hábitat y la desaparición simultánea de especies endémicas del género Astroblepus. En general, los suelos de la cordillera de los Andes se caracterizan por su fertilidad, por lo que extensas regiones han sido transformadas para la agricultura y el pastoreo de ganado, procesos que requieren del uso de agua proveniente de arroyos y manantiales, lo cual conlleva cambios notables en la configuración natural de estos sistemas de agua, así como la desaparición de peces, zooplancton y flora acuática. A pesar de estas acciones antrópicas, algunas especies de Astroblepus parecen tener la capacidad de responder rápidamente a las transformaciones del hábitat y de sobrevivir en estas condiciones Se discute aquí la incidencia de la perturbación del hábitat en un tramo de arroyo con presencia de Astroblepus mariae. Palabras clave: perturbación de hábitat, supervivencia, refugio, zona amortiguadora.