Lithogenes

Abstract: A phylogenetic study of the Loricariidae with emphasis on the Neoplecostominae is presented based on a maximum parsimony analysis of 268 phenotypic characters encompassing osteology, arthrology, and external morphology. Results support previous hypotheses of the monophyly of the Neoplecostominae and each of the included genera: Hirtella, Isbrueckerichthys, Kronichthys, Neoplecostomus, Pareiorhaphis, and Pareiorhina. In addition, previously undiscovered diversity was revealed within the subfamily as an additional genus-level taxon, herein described as Euryochus. Relationships among neoplecostomine genera are: (Kronichthys (Euryochus ((Hirtella + Pareiorhaphis) (Pareiorhina (Isbrueckerichthys + Neoplecostomus))))). Additional undescribed diversity was also detected among most neoplecostomine genera and the Hypoptopomatinae. In addition, recently discovered genera Nannoplecostomus and Microplecostomus were included in the analysis, and were identified as sequential sister-taxa to Neoplecostominae + Hypoptopomatinae, which are currently not included in any subfamily and regarded as incertae sedis in Loricariidae. The three species of Lithogenes were included in an encompassing phylogenetic analysis for the first time, and were identified as a monophyletic unit and sister group to all remaining loricariids. The other loricariid subfamilies were also corroborated as monophyletic, and presented the following interrelationships (Lithogeninae (Delturinae (Loricariinae (Hypostominae (Nannoplecostomus (Microplecostomus (Hypoptopomatinae + Neoplecostominae). The Neoplecostominae and its genera are phylogenetically diagnosed, and hypothesized relationships are compared to those of previous morphological and molecular phylogenetic studies.

Abstract: 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 seri...

Abstract: A new species of the loricariid genus Lithogenes Eigenmann, 1909, is described on the basis of 84 specimens captured from a single locality in the upper Rio Orinoco drainage of southern Venezuela. The new species is only the third representative of the subfamily Lithogeninae to be recognized in the 100 years since the discovery of the type species, L. villosus, and is the only lithogenine known from more than a handful of specimens. This new material provides the basis for a comprehensive review of lithogenine systematics, comparative anatomy, and interrelationships. Lithogenes wahari, new species, shares with its congeners the dermal plates of the trunk comprised of three paired series, presence of a bifurcate levator arcus palatini crest and expanded lateral lamina of the hyomandibula, and the palatine sesamoid not reaching the nasal capsule, thus confirming its placement in Lithogenes among the Loricariidae. The new species is diagnosed among congeners by the absence of odontodes on the proxim...