Redescription of Astyanax obscurus (Hensel, 1870) and A. laticeps (Cope, 1894) (Teleostei: Characidae): two valid freshwater species originally described from rivers of Southern Brazil

Abstract

Astyanax obscurus and A. laticeps are redescribed. Both species were originally described from the laguna dos Patos system, Rio Grande do Sul, Brazil. The deepest and most robust body area close to the middle of the pectoral fins length, robust head, snout short and abrupt, body depth smaller than 41% of SL, reduced number of branched anal-fin rays, presence of one or two humeral spots, and a dark midlateral body stripe extending to the tip of the middle caudal-fin rays include both in the A. scabripinnis species complex. The presence of two humeral spots (vs. one), external row of the premaxillary with pentacuspid teeth (vs. tricuspid), and absence of bony hooks in all fins in males (vs. presence in anal and ventral fins) distinguish A. obscurus from A. laticeps. These species distinguish from species of this complex by meristic and morphometric characters and color pattern. An identification key for the species of genus occurring in the laguna dos Patos system is presented.Astyanax obscurus e A. laticeps são redescritas. Ambas espécies foram descritas do sistema da laguna dos Patos, Rio Grande do Sul, Brasil. A maior altura e robustez do corpo na vertical que passa pela metade do comprimento das nadadeiras peitorais, cabeça robusta, focinho curto e abrupto, altura do corpo menor que 41% do CP, reduzido número de raios ramificados na nadadeira anal, presença de uma ou duas manchas umerais e barra escura horizontal na linha média do corpo estendendo-se até a extremidade dos raios da nadadeira caudal permitem sua inclusão no complexo de espécies A. scabripinnis. A presença de duas manchas na região umeral (vs. uma única), fileira externa do pré-maxilar com dentes pentacuspidados (vs. tricuspidados) e ausência de ganchos nas nadadeiras de exemplares machos (vs. presença nas nadadeiras anal e ventral) distinguem A. obscurus de A. laticeps. Estas espécies diferem das demais incluídas no complexo por caracteres merísticos e morfométricos e padrão de colorido. É fornecida uma chave de identificação para as espécies do gênero ocorrentes no sistema da laguna dos Patos.

Comparative morphology of gill glands in externally fertilizing and inseminating species of cheirodontine fishes, with implications on the phylogeny of the family Characidae (Actinopterygii: Characiformes)

“…Among taxa of Clade A, gill glands were found to be present on histological preparations by JRB (unpublished) in mature inseminating males of Creagrutus melasma and Monotocheirodon species, and in mature males of externally fertilizing species of the genera Bryconamericus, Caiapobrycon, Creagrutus, Cyanocharax, Hemibrycon, Hypobrycon, Knodus, Piabina, Rhinobrycon, and Rhinopetitia. The absence of a gill gland has been registered for some taxa belonging to Clade C of Javonillo et al (2010) and Oliveira et al (2011), further supporting this hypothesis: Astyanax utiariti by Bertaco & Garutti (2007) courensis by , Astyanax obscurus and A. laticeps by Bertaco & Lucena (2010), Ectrepopterus uruguayensis by Malabarba et al (2012) [see Thomaz et al, 2010 for the relationships of Ectrepopterus uruguayensis, formerly as Hyphessobrycon uruguayensis, with clade C taxa], Hasemania kalunga by , Hemigrammus tocantinsi by Carvalho et al (2010), Hemigrammus ora by , Hyphessobrycon melanostichos and Hyphessobrycon notidanos by Carvalho & Bertaco (2006), Hyphessobrycon vinaceus by , and Oligosarcus itau by Mirande et al (2011).…”

Ichthyofauna of the hydrographic basin of the Chasqueiro Stream (Mirim Lagoon system, southern Brazil): generating subsidies for conservation and management

“…The collected fish were stored in plastic bags, labeled, and fixed in 10% formalin, and were then taken to the laboratory where they were transferred to 70% alcohol. Specimens were identified with the help of specialized literature (Reis & Malabarba 1988, Buckup & Reis 1997, Rodriguez & Reis 2008, Caravalho & Reis 2009, Bertaco & Lucena 2010, Carvalho et al 2012, Lucena et al 2013, Malabarba et al 2013, and specialists were consulted when needed for species confirmation. The list of species was formulated according to Wiley & Johnson (2010) and Malabarba et al (2013).…”

Astyanax guaricana (Ostariophysi: Characidae), a new species from the rio Cubatão drainage, Paraná State, Southern Brazil

“…The first was A. laticeps (Cope, 1894), recently redescribed by Bertaco & Lucena (2010) who expanded its distribution to this river drainage, in the southern Paraná State.…”