Abstract
Two new species of loricariid catfishes, Parotocinclus bidentatus and P. muriaensis, are described from the rio Paraíba do Sul basin. They possess accessory unicuspid teeth located internally to the series of bicuspid teeth in premaxillary and dentary bones. According to a parsimony analysis of phylogenetic relationships among the Hypoptopomatinae, the new taxa are members of the genus Parotocinclus, even though they lack a fully developed adipose fin. They differ from most species of Parotocinclus because they have accessory teeth. Within the Hypoptopomatinae, accessory teeth are also found only in P. collinsae and members of the genera Eurycheilichtys, Epactionotus and Niobichthys.
Highlights
Two new species of Hypoptopomatinae were discovered during an inventory of the subfamily in the ichthyological collection of the Museu Nacional (MNRJ), Rio de Janeiro, Brazil
In all parsimonious trees (Fig. 3) Parotocinclus bidentatus and P. muriaensis form a monophyletic pair of sister taxa that is more closely related to a subset of species of Parotocinclus than to any other genus of the subfamily Hypoptopomatinae
The subset includes P. maculicauda which is the type species of Parotocinclus. Based on these phylogenetic results we decided to describe the two new species as members of the genus Parotocinclus, we are aware that the examined specimens lack a fully developed adipose fin, which is traditionally used as a diagnostic character in the identification of the genus
Summary
Two new species of Hypoptopomatinae were discovered during an inventory of the subfamily in the ichthyological collection of the Museu Nacional (MNRJ), Rio de Janeiro, Brazil. The specimens stood out due to the presence of accessory unicuspid teeth behind the series of bicuspid teeth in premaxillary and dentary bones. This character is shared only with Parotocinclus collinsae Schmidt & Ferraris, 1985, and the genera Epactionotus, Eurycheilichthys, and Niobichthys (Schmidt & Ferraris, 1985; Reis & Schaefer, 1992; Reis & Schaefer, 1998; Schaefer & Provenzano, 1998). The new species are members of the Otothyrini (Schaefer, 1991) according to a preliminary cladistic analysis using the data matrix of Schaefer (1998). We describe the two species as provisional members of the genus Parotocinclus and present a brief discussion of the phylogenetic hypothesis that supports such placement
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