Brazilian scientists have described two new species of green miniature loricariid catfish from the Madeira River drainage in Brazil.
The two new species are named Acestridium gymnogaster and A. scutatum by Roberto Reis and Pablo Lehmann in the latest issue of the journal Copeia.
Acestridium gymnogaster differs from congeners in having a short nasal plate not reaching the anterior margin of the lateral ethmoid, the first bilateral postrostral plates not contacting each other midventrally, two or three prenuchal plates, one or two paired predorsal plates anterior to the prenuchal plates, three or four medial unpaired predorsal plates, chromatophores arranged in lines between the aligned odontodes of the predorsal area, a smooth inner margin of the pectoral-fin spine, the lateral abdominal plates extending to midventral line only posteriorly and always leaving an unplated midventral area anteriorly, and 12 branched caudal-fin rays.
Acestridium scutatum differs from congeners in having a long snout, the first bilateral postrostral plates not contacting each other midventrally, one or two paired predorsal plates anterior to the prenuchal plates, two median unpaired predorsal plates, the inner margin of the pectoral-fin spine smooth or with very fine serrations, a middle series of abdominal plates between the lateral abdominal plates, a preanal plate with well developed anterior and posterior lateral expansions, and 12 branched caudal-fin rays.
Both these species were collected in shallow streams (0.5"1.5 m deep, 5"20 m wide), with a sandy bottom, clear or slightly black water, moderate water current, and dense aquatic and marginal vegetation.
For more information, see the paper: Reis, RE and P Lehmann A (2009) Two new species of Acestridium Haseman, 1911 (Loricariidae: Hypoptopomatinae) from the Rio Madeira basin, Brazil. Copeia 2009, pp. 446"452.