Two new Rineloricaria plecos described

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Two new plecos in the genus Rineloricaria have been described by Brazilian scientists in the latest issue of the journal Copeia.

Mnica Rodriguez and Roberto Reis describe Rineloricaria malabarbai and R. baliola in a taxonomic review of the Rineloricaria from the Laguna dos Patos drainage in southern Brazil.

The authors recognize four other species within the Laguna dos Patos drainage and rediagnose them in this study: R. strigilata, R. cadeae, R. microlepidogaster, and R. longicauda.

They also divide Rineloricaria into two species groups based on habitat preferences and morphological differences: the sandy group and the rocky group.

According to the authors, pecies in the sandy group usually have light-brown or yellowish background color, abdomen completely covered with platelets between the lateral abdominal plates, head narrow (usually narrower or equal to trunk width), snout pointed, naked area at tip of snout elongated, reaching the most anterior pore of the infraorbital ramus of sensory canal, four series of lateral plates, with the mid-dorsal series being absent, dorsal-fin spinelet absent, and are more commonly found on soft bottoms of sand or mud. Species in this group are R. cadeae, R. catamarcensis, R. felipponei, R. kronei, R. longicauda, R. misionera, R. pareiacantha, R. quadrensis, R. steindachneri, R. strigilata, and R. thrissoceps.

Species on the rocky group, alternatively, usually have dark-brown or dark gray background color, abdomen variable from almost completely naked to fully plated (including wide intraspecific variation), head broad (usually wider than trunkwidth), snout broad and round, naked area at tip of snout oval-shaped, not reaching the most anterior pore of the infraorbital ramus of sensory canal, five series of lateral plates, the mid-dorsal series being short and limited to the predorsal and dorsal-fin base area, dorsal-fin spinelet present, and are more frequently found on rocky bottoms. Species in this group are R. aequalicuspis, R. baliola, R. jaraguensis, R. latirostris, R. malabarbai, R. maquinensis, R. microlepidogaster, and R. pentamaculata.

Rineloricaria malabarbai This species is distinguished from other members of the genus except R. maquinensis by its unique pattern of abdominal plates: abdomen almost completely naked, except for a single preanal complex of plates, connected to the lateral abdominal plates by one or two small squarish platelets at the base of pelvic-fin spine (vs. squarish platelets absent in specimens with naked or almost naked abdomens). It differs from R. maquinensis by the following body proportions: longer predorsal length (31.2"35.0 vs. 28.2"31.5% standard length), shorter postanal length (52.3"56.4 vs. 55.5"62.5% standard length), longer abdominal length (15.2"17.8 vs. 13.6"15.5% standard length), wider cleithral width (16.8"19.6 vs. 13.7"16.5% standard length), and a deeper head (43.2"64.8 vs. 37.4"43.9% head length).

Rineloricaria malabarbei inhabits watercourses with slow to fast flow, clear or brown water, and is usually found on rocky bottoms. The species is named after Brazilian ichthyologist Luiz Malabarba.

Picture kindly supplied by Mnica Rodriguez

Rineloricaria baliola Rineloricaria baliola is distinguished from all other members of the genus by its unique color pattern comprising one dark, wide band covering most of the distal half of all fins. It is also distinguished from other species in the rocky group (except Rineloricaria microlepidogaster) by its snout with roundish naked area, which generally reaches to the anteriormost pore of the infraorbital ramus of the sensory canal (vs. roundish naked area not reaching to the anteriormost pore of the infraorbital ramus of the sensory canal or an elongate naked area).

The new species is named after its colour pattern (Latin baliolus, meaning chestnut or reddish brown), and inhabits watercourses with slow to fast flow, clear or reddish water, and rocky, sandy, or muddy bottom.

Picture kindly supplied by Mnica Rodriguez

For more information, see the paper: Rodriguez, MS and RE Reis (2008) Taxonomic review of Rineloricaria (Loricariidae: Loricariinae) from the Laguna dos Patos drainage, southern Brazil, with the descriptions of two new species and the recognition of two species groups. Copeia 2008, pp. 333"349.