taxonID	type	description	language	source
C3378791FFFC3712FF09FCF9FD2A149E.taxon	description	Results of the PCA analyses indicate that Sternarchella sima and S. orinoco exhibit distinct phenotypes (Fig. 7), whereas S. terminalis and S. orthos are morphologically indistinguishable according to the characters examined (Fig. 8). A preliminary analysis using geometric morphometric of head neurocranial shape in lateral views recovered similar results (K. Evans and J. Albert, pers. obs.), finding statistically significant differences between S. sima and S. orinoco (P <0.001), and no significant differences between S. terminalis and S. orthos (P = 0.1037). The osteological data reviewed here indicate that S. orthos has a narrower orbitosphenoid (character 33) and more pharyngobranchial teeth (character 59) than S. terminalis (14 or more vs. 13 or less). However, both of these characters may have dubious taxonomic value, being variable within many apteronotid species (Albert, 2001), and exhibiting relatively high homoplasy on the tree of Fig. 9 (CI = 0.25 and 0.20, respectively). The reliability of these characters as diagnostic traits for S. terminalis therefore needs to be tested with larger sample sizes. Given the relatively poor geographic sampling of individuals from across the large range of these species, it seems premature to advance any formal nomenclatural changes, and we provisionally recognize S. orinoco and S. orthos from the Orinoco basin as valid species.	en	Ivanyisky Iii, Stephen J., Albert, James S. (2014): Systematics and biogeography of Sternarchellini (Gymnotiformes: Apteronotidae): Diversification of electric fishes in large Amazonian rivers. Neotropical Ichthyology 12 (3): 565-584, DOI: 10.1590/1982-0224-20130159, URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252014000300565&lng=en&tlng=en
C3378791FFFC3712FF09FCF9FD2A149E.taxon	discussion	Origin of the deep-channel electric fish fauna The Sternarchellini represents an excellent taxon in which to study the contributing roles of geography and ecology in the formation of the diverse and specialized deep-channel Neotropical fish fauna. In some clades of deep-channel apteronotids, several closely-related species occur together in sympatry and syntopy, such as in Adontosternarchus, Porotergus, Sternarchella, Sternarchogiton, and Sternarchorhynchus (Crampton & Albert, 2006; Crampton et al., 2011). Other gymnotiform clades are also diverse in the deep-channel habitat, including the sternopygids Eigenmannia and Rhabdolichops, and the rhamphichthyid Rhamphichthys (Albert et al., 2011 b; Carvalho, 2013). The presence of multiple sympatric congeners within this habitat, including several instances of sister-species pairs, is unusual among Neotropical fishes, where most sister-species pairs are distributed in allopatry (Albert & Crampton, 2001; Albert & Reis, 2011; Albert et al., 2011 a). The Sternarchellini is part of the diverse assemblage of apteronotid fishes that inhabits the large rivers of tropical South America (Mago-Leccia et al., 1985; Lundberg & Lewis, 1987). A high proportion (70 of 85, or 82 %) of apteronotid species are restricted to the deep channels of the Amazon and Orinoco rivers and their large tributaries. This concentration of species in the deep channels is notable considering the small proportion (2.6 %) of the total bottom area that these channels occupy in the tropical South America (Goulding et al., 2003; Winemiller & Willis, 2011). Even accounting for the larger volume of large rivers (stream orders 6 - 10), the total amount of habitat space they occupy is small compared to that of all the small rivers and streams (stream orders 1 - 5) combined, that drain more than 11 million km 2 (Albert & Crampton, 2005 a; Crampton & Albert, 2006; Crampton et al., 2011). The origin of deep-channel habits by the Navajini, including the Sternarchellini, may have occurred before the separation of the modern Amazon and Orinoco basins, an event that followed the rise of the Vaupes Arch in the Late Miocene (ca. 10 - 8 Ma; Dobson, 2001; Winemiller & Willis, 2011). The Navajini includes several clades with multiple sisterspecies pairs and other supraspecific taxa distributed across theAmazon-Orinoco divide. Clades with multiple multispecies assemblages co-exist in both basins (Albert et al., 2011; Albert & Carvalho, 2011). The Amazon and Orinoco basins are connected on the modern landscape via the Casiquiare Canal, but this waterway probably does not act as a dispersal corridor for most sternarchelline fishes. Sternarchellines are lowland species, and to date no sternarchelline species have been collected from within the Casiquiare Canal or the rivers connected to it above the rapids around the base of Guiana Shield, in either the upper rio Negro or upper río Orinoco basins (i. e., rapids at São Gabriel and Puerto Ayacucho, (Winemiller & Willis, 2011). The phylogenetic position of Magosternarchus, nested within Sternarchellini, helps explain the evolution of the extreme phenotypic, behavioral, and ecological specializations of these deep-channel species. The large jaws and robust dentition of Magosternarchus are used in predation, in particular on the tails of other gymnotiforms (Lundberg et al., 1996). Previous studies concluded that Magosternarchus is the sister taxon of the clade composed of Sternarchella (Lundberg et al., 1996), or of Sternarchella and Pariosternarchus (Albert & Crampton, 2006). Under these hypotheses the large jaws, terminal or superior mouth position, and aggressive behaviors of some Sternarchella species are interpreted to have independently evolved from the conditions observed in Magosternarchus. However, according to our phylogenetic results, the genus Sternarchella is found to be paraphyletic, including the two species currently assigned to the genus Magosternarchus (Fig. 9). This result suggests that the large jaws, terminal or superior mouth positions and aggressive predatory behaviors of some Sternarchella species and Magosternarchus are homologous. Five characters support a relationship between Magosternarchus, S. schotti and the S. terminalis species group: IO less than 20 % HL (CI = 0.25), anterior mesethmoid straight in lateral view (CI = 0.50), lateral ethmoid large and hour-glass shaped (CI = 1.00), supraoccipital crest dorsal process (CI = 1.00), and endopterygoid process oblique in orientation (CI = 0.50).	en	Ivanyisky Iii, Stephen J., Albert, James S. (2014): Systematics and biogeography of Sternarchellini (Gymnotiformes: Apteronotidae): Diversification of electric fishes in large Amazonian rivers. Neotropical Ichthyology 12 (3): 565-584, DOI: 10.1590/1982-0224-20130159, URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252014000300565&lng=en&tlng=en
