Abstract
Three new species of Loricaria are described from large white- and black-water river channels of the Amazon basin of Brazil, the upper rio Negro drainage of southern Venezuela, and clear waters of the lower rio Tocantins. Loricaria spinulifera and L. pumila differ from other species of Loricaria by having unique patterns of abdominal plate development and hypertrophied odontodes forming conspicuous crests on dorsal surfaces of the head and predorsal plates. Both are small species of Loricaria, reaching sexual maturity at less than 120 mm SL, and exhibiting sexually dimorphic characters consistent with members of the L. cataphracta complex. Loricaria spinulifera differs from L. pumila in having a unique arrangement of buccal papillae and large thorn-like odontodes on the dorsum of the head. Loricaria pumila is the smallest known Loricaria, reaching sexual maturity at less than 80 mm SL. Loricaria lundbergi differs from other Loricaria by having a unique abdominal plate pattern, broad head, and small basicaudal plate. Loricaria lundbergi is sympatric with L. spinulifera in the lower rio Negro drainage, but is also known from the rio Baria system of the Casiquiare drainage. Loricaria pumila occurs in the lower rio Amazonas and lower rio Tocantins. All three new species exhibit varying degrees of reduction in eye size and pigmentation seen in other fishes inhabiting deep river channels of South America.
Highlights
Loricaria Linnaeus, 1758, was the first loricariid taxon described with L. cataphracta as the type species
This study reveals three new species of Loricaria, two of which (L. spinulifera and L. pumila) have several additional unique features not shared among known congeners and one (L. pumila) attains a smaller adult size than any other member of the genus
Specimens of Loricaria spinulifera and L. pumila from benthic trawl samples exhibit variation in eye size and development that is apparently influenced by depth (Fig. 5) and perhaps water clarity
Summary
Loricaria Linnaeus, 1758, was the first loricariid taxon described with L. cataphracta as the type species. More than half of all species in the subfamily Loricariinae have been at some point assigned to Loricaria (Isbrücker, 1981), most of these have since been transferred to other genera. Loricaria species are most readily distinguished from other loricariine genera based on the presence of elongate, slender filaments on the lips and a low number of bicuspid premaxillary teeth (usually three to four per side) that are about twice the length of the dentary teeth. In a recent phylogenetic assessment of the Loricariinae, based on combined analysis of molecular and morphological data sets, Covain et al (2008) confirmed the monophyly of several morphologically diagnosed groups within the Loricariini, including the Loricaria group and the closely related Pseudohemiodon group; species diversity, geographic distributions and interrelationships within Loricaria are poorly understood and are currently under investigation by the senior author
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