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Two new ancistrin genera and species are described from main channels and tributaries of the upper Orinoco River in Amazonas, Venezuela. Micracanthicus vandragti is black with white spots and distinguished by its small body-size, large gas-bladder capsules, and highly protrusible mandibles with short tooth cups and five to eight long teeth per tooth cup. The known range of Micracanthicus vandragti is restricted to the lower Ventuari River and portions of the Orinoco River near its rocky, anastomose confluence with the Ventuari River. Soromonichthys stearleyi is green with small yellow-gold spots on the head and thin vertical bars on the body and has long dentary and premaxillary tooth cups with 39-69 teeth per tooth cup. It is distinguished by its coloration and by its unique pattern of plate loss on the snout: plates absent from mesethmoid surface and anteriormost margin of snout. Soromonichthys stearleyi is known only from Soromon Creek, a northern tributary of the upper Orinoco draining southern slopes of Mount Duida. [ABSTRACT FROM AUTHOR]

Baryancistrus beggini, new species, is described from the upper Rio Orinoco and lower portions of its tributaries, the Rio Guavlare in Colombia and Rio Ventuari in Venezuela. Baryancistrus beggini is unique within Hypostominae in having a uniformly dark black to brown base color with a blue sheen in life, and the first three to five plates of the midventral series strongly bent, forming a distinctive keel above the pectoral fins along each side of the body. It is further distinguished by having a naked abdomen, two to three symmetrical and ordered predorsal plate rows including the nuchal plate, and the last dorsal-fin ray adnate with adipose fin via a posterior membrane that extends beyond the preadipose plate up to half the length of the adipose-fin spine. [ABSTRACT FROM AUTHOR]

A new species of the previously monotypic loricariid subfamily Lithogeninae is described from northern Venezuela. Lithogenes valencia is the first representative of the subfamily to be discovered subsequent to the discovery and description of Lithogenes villosus Eigenmann, 1909, from Guyana and extends the geographic distribution of the subfamily beyond the Guyana Shield region of northeastern South America. The new species shares several derived features with L. villosus that are not observed among other Loricariidae. It is diagnosed from L. villosus by the broader head, 27-29% SL (vs 22% SL), 25-29 premaxillary teeth (vs 9-10), the presence of nine (vs 8) branched pectoral-fin rays, anal fin rays ii,5 (vs ii,7), straight (vs sickle-shaped) lateropterygium, and by the presence of small plates in the dorsal and ventral series of the lateral trunk irregularly arranged and not contacting the plates of the median series (vs plates larger, regularly arranged in series, in contact with the median series plates posteriorly). Lithogenes valencia is known only from six specimens collected from the basin of Lago de Valencia, an endorrheic lake basin occupying a tectonic graben situated between the coastal and interior ranges of the Cordillera de La Costa of north-central Venezuela. Subsequent collecting efforts have failed to obtain additional specimens and the species may now be extinct, since the lake and its tributaries have become severely degraded by pollution and disturbance. Aspects of its peculiar morphology are described and illustrated, and we provide evidence for its sister-group relationship to L. villosus. Presently isolated and undergoing rapid desiccation and contamination, Lago de Valencia had a recent connection with the Orinoco... [ABSTRACT FROM AUTHOR]