Abstract
Characidium samurai, a species of the family Crenuchidae apparently endemic to rio das Almas and rio Vermelho basins, Bahia, Brazil, is described. The new species is readily distinguishable from its congeners, except C. lanei, by having a dark lateral band along the head and body that is particularly broad from the rear of the head to the end of the caudal peduncle (1.5 or 2 scales wide) and by the absence of dark bars or blotches on the ventral half of the body. Characidium samurai differs from C. laneiby having the lateral band with straight borders overall (vs.lateral band with somewhat irregular borders due to blotches extending dorsally or ventrally), anal fin ii,7-8 (vs. ii,6), and 4 horizontal scale rows above the lateral line and 4 below (vs. 5/3). It further differs from congeners by a series of features, including isthmus completely covered by scales, lateral line complete with 34-37 perforated scales, 9 scales on the transversal line, 14 scale rows around the caudal peduncle, anal fin ii,7-8, and the absence of dark bars or spots on the fins, except by a faded dorsal-fin bar. The presence of pseudotympanum in four species of Characidium is discussed.
Highlights
Characidium Reinhardt is the most diverse genus of the family Crenuchidae, with 56 valid species of small Neotropical fishes that are distributed from Argentina to Panama (Buckup, 2003; Graça et al, 2008; Silveira et al, 2008; Peixoto & Wosiacki, 2013; Lujan et al, 2013; Netto-Ferreira et al, 2013)
Two species of Characidium have been described from northeastern Brazil: C. bahiense Almeida from Arembepe, Bahia, and C. bimaculatum Fowler from Fortaleza, Ceará
A series of recent publications, including inventories and ecological studies in some of these rivers, revealed a broad occurrence of species identified as Characidium sp. (e.g., Sarmento-Soares et al, 2007, 2008, 2009; Sarmento-Soares & Martins-Pinheiro, 2009; Cetra et al, 2010), C. cf. bahiense and C. cf. bimaculatum (e.g., Santos & Caramaschi, 2007, 2011) or C. aff. timbuiense and C. aff. zebra (e.g., Burger et al, 2011; Cetra et al, 2011), attesting to the taxonomic difficulties regarding the identification of species in the genus
Summary
Characidium Reinhardt is the most diverse genus of the family Crenuchidae, with 56 valid species of small Neotropical fishes that are distributed from Argentina to Panama (Buckup, 2003; Graça et al, 2008; Silveira et al, 2008; Peixoto & Wosiacki, 2013; Lujan et al, 2013; Netto-Ferreira et al, 2013). Two species of Characidium have been described from northeastern Brazil: C. bahiense Almeida from Arembepe, Bahia, and C. bimaculatum Fowler from Fortaleza, Ceará. Three other species were described from nearby drainages, C. fasciatum Reinhardt and C. lagosantense Travassos from the rio São Francisco basin and C. timbuiense Travassos from the rio Timbuí basin, a coastal drainage of Espírito Santo State. A series of recent publications, including inventories and ecological studies in some of these rivers, revealed a broad occurrence of species identified as Characidium sp. Collecting efforts performed in the last eight years in the costal drainages of Bahia have revealed various undescribed species of Characidium, including one described in the present study, apparently endemic to the small drainages of rio das Almas and rio Vermelho
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