The Pygidiidæ, a family of South American catfishes, by Carl H. Eigenmann.

Abstract

The Pygidiidce are a family of South American catfishes distinguished externally by the absence of an adipose fin and by the posterior position of the dorsal. Most of them are even more readily distinguished by the presence of spines or thorns on the opercle and interopercle, by twin barbels at the angle of the mouth, and by the absence of all mental barbels. Other characters of the catfishes may be present or absent, and by addition, subtraction, or modification of characters, various subfamilies have been formed. A description of the characteristic structures is given on pages 276-279. The basal habit of all the members of the family is that of burrowing. The opercular and interopercular spines are an adaptation to their habit of insinuation, which is at the root of the commensalism, parasitism, and worse, to which some highly specialized members of the family are addicted. Nematogenys from central Chile, the only representative of the Nematogenyince, is probably more nearly like the ancestors of the Pygidiidce than the other living representatives of the family. It recalls the Siluridce by having a pungent pectoral spine, serrated on its posterior margin, by having but one barbel at the angle of the mouth (the remaining subfamilies having two), by having a pair of mental barbels,

A new catfish species of the genus Trichomycterus (Siluriformes: Trichomycteridae) from the río Orinoco versant of Páramo de Cruz Verde, Eastern Cordillera of Colombia

“…brachykechenos), all remaining species of Trichomycterus whose neurocrania have been described and illustrated (e.g., T. taroba Wosiacki & Garavello, 2004) show a long roughly rectangular fontanel, extending anteriorly between the posterior part of the frontals, interrupting their midline articulation, and reaching posteriorly the center of the parieto-supraoccipital. This condition is also exhibited by the other genera traditionally assigned to Trichomycterinae (Eigenmann, 1918;Arratia, 1990Arratia, , 1998Arratia et al, 1978;Datovo & Bockmann, 2010): Bullockia Arratia, Chang, Menu-Marque & Rojas, 1978;Eremophilus Humboldt, 1805;Hatcheria Eigenmann, 1909;Rhizosomichthys Miles, 1943;Scleronema Eigenmann, 1918 andSilvinichthys Arratia, 1998 (pers. obs.…”

“…4-5) (vs. not prolonged as a filament), 7-8 branched pectoral-fin rays (vs. 5-6), dorsal-fin origin at same level of pelvic-fin insertion (vs. at vertical through last third of pelvic fin), anal-fin origin posterior to dorsal-fin base (vs. at vertical through middle of dorsal-fin base), anal fin with seven basal radials (vs. six), procurrent caudal-fin rays 16-21 dorsally and 14-17 ventrally (vs. 15-16 and 10-13, respectively), and by the color pattern of lateral surface of body consisting in background dark brown with a thin mid-lateral dark stripe (vs. background light yellow with superficial layer of densely mottled dark brown). Trichomycterus steindachneri is further distinguished from T. dorsostriatus (Eigenmann, 1918), which also occurs in the río Meta system, by having 40 or 41 free vertebrae (vs. 37), dorsal fin inserted just posterior to neural spine of vertebrae 18 or 19 (vs. vertebra 16), analfin origin behind posterior end of dorsal-fin base, inserted just posterior to hemal spine of vertebrae 22-24 (vs. under posterior portion of dorsal-fin base, just posterior to vertebra 20), a single upper hypural plate (vs. two upper hypural plates), and by the color pattern consisting in a thin mid-lateral dark stripe (vs. a dark band or row of spots from just above the gill-opening to the base of the upper caudal-fin rays). Trichomycterus steindachneri can also be differentiated from the only other species described from western tributaries of the Orinoco in Colombia, T. migrans (río Guaviare system), by its maxillary barbel extending beyond pectoral-fin origin (vs. scarcely reaching this point), anal-fin origin entirely behind dorsal-fin base (vs. at vertical through base of last dorsal-fin ray), and caudal-fin margin slightly rounded (vs. deeply emarginated).…”

New data on cistern catfish, Phreatobius cisternarum, from subterranean waters at the mouth of the Amazon River (Siluriformes, Incertae Sedis)

“…Its aberrant external morphology, which includes several reductive features, has rendered traditional diagnostic characters for catfish families mostly uninformative for the taxonomic placement of Phreatobius. Since its discovery, P. cisternarum has been aligned with at least five different families, alone or in various combinations: Clariidae and Plotosidae (Fuhrmann, 1905(Fuhrmann, , 1906, Trichomycteridae and Cetopsidae (Goeldi, 1905;Eigenmann, 1918;Myers, 1944), and Pimelodidae or Heptapteridae (Reichel, 1927;Myers & Weitzman, 1966;Buckup, 1988;Bockmann, 1998). Most of those proposals have not relied on osteological information, because of the scarcity of material for examination.…”

¿Qué factores determinan la distribución altitudinal de los peces de ríos tropicales andinos?

“…Se utilizó para la identificación las claves de Eigenmann (1918), Géry (1977) y Pearson (1924. Los peces fueron depositados en el Museo de Historia Natural Alcide d'Orbigny (Cochabamba, Bolivia), y los macro-invertebrados se depositaron en la colección de la Unidad de Limnología y Recursos Acuáticos de la Universidad Mayor de San Simón (Cochabamba, Bolivia).…”