Volume 22, Issue 3 – 15 July 2016
Volume 22, Issue 3 – 15 July 2016
Frank Pezold, Ray C. Schmidt and Melanie L. J. Stiassny: A Survey of Fishes of the Geebo – Dugbe River Confluence, Sinoe County, Liberia, with an Emphasis on Tributary Creeks, pp. 97-122
A survey of the ichthyofauna of the Geebo-Dugbe watershed in Sinoe County, Liberia was undertaken in anticipation of future economic developments. The watershed lies between Sapo National Park and the Grand Kru-River Gee National Forest and is believed to serve as a wildlife corridor between the two preserves. Small first or second order streams predominated in the region. Stream sites visited varied from minimal to severe in the degree of impact from artisanal mining, logging and agriculture, yet forty-five species representing 20 families were recorded from the watershed. The diversity of species obtained in this small area of the Dugbe River basin compares well with studies of other West African rivers in the Upper Guinean Province. Consistent with the correlation of species number with the size of the immediate watershed and position in the basin as a whole, species richness of individual collections was low, only occasionally higher than 8-10 species at a single site. Fish biomass or abundance was also low. Epiplatys olbrechsti, an undescribed Epiplatys species, ‘Barbus’ cf. guildi, Hemichromis bimaculatus, Bryconalestes longipinnis and Amphilius atesuensis were commonly encountered in the small streams. The most abundant species taken from cascades in the Geebo River were Doumea chapuissi, Labeobarbus wurtzi, Parasicydium bandama and Sicydium crenilabrum. Five of the species reported here represent new records for Liberia – Marcusenius meronai, Bryconalestes derhami, ‘Barbus’ cf. guildi, Parasicydium bandama and Sicydium crenilabrum. Our discoveries of other species in the basin represent range extensions significant to understanding their distributions throughout the region.
Flávio C. T. Lima, Vanessa Correa and Rafaela P. Ota: A new species of Hemigrammus Gill 1858 (Characiformes: Characidae) from the western Amazon basin in Peru and Colombia, pp. 123-132
Hemigrammus aguaruna, new species, is described from tributaries of the Río Maranõn, Departamento Loreto, Peru, and is also recorded from Leticia, Departamento Amazonas, Colombia. The new species belongs to the Hemigrammus ocellifer species group, sharing with the remaining species of the group the presence of two humeral blotches, a caudal peduncle blotch, the upper margin of the eye red in living specimens, and the presence in adult males of a single midlle-sized hook on the last unbranched and anteriormost branched anal-fin rays. Hemigrammus aguaruna can be readily distinguished from the remaining congeners of the Hemigrammus ocellifer species group, with exception of H. yinyang, by presenting a very conspicuous, intensely dark, roughly oval, horizontally elongated second blotch (vs. second humeral blotch less developed than the first humeral blotch, vertically elongated and very narrow). Comments on the recent revalidation of Hemigrammus falsus are presented.
Nelson Flausino Junior, Francisco A. Machado, Jansen S. Zuanon and Efrem J. Ferreira: The fish fauna of sessile hydrophytes stands (Mourera spp.: Podostemaceae) in the Dardanelos Waterfalls, Rio Aripuanã, Brazil, pp. 133-144
The upper Rio Aripuanã, a clear water tributary of Rio Madeira, Mato Grosso, Brazil, present extensive rapids stretches, which culminate in the Dardanelos and Andorinhas waterfalls complex. In these environments, stands of sessile plants of the family Podostemaceae harbor several species of strongly rheophilic fish. This study aimed to characterize the fish fauna associated with the stands of Podostemaceae at the rio Aripuanã, describing the trophic ecology of the species, as well as the general trophic structure of these fish assemblages. The study was based on direct underwater observation of fish during snorkeling sessions in the rapids, as well as on examination of specimens collected using standardized fishing methods and sampling
efforts. Multivariate analysis was used to evaluate the main pattern of spatial and temporal changes in fish assemblages associated with Podostemaceae stands. Overall, 29 species of fish were found associated with plant stands, but occupying
different microhabitats among the hydrophytes and using specialized foraging tactics. Most fish species consumed predominantly autochthonous food items. Rapids stretches and waterfalls are particularly sensitive to anthropic impacts that could cause the disappearance of Podostemaceae communities and their associated fauna. The conservation of this stretch of the rio Aripuanã is very important to maintain these rheophilic plants and its associated fish fauna.
Hypomasticus pachycheilus, Rio Aripuanã, Mato Grosso, Brazil. Photo by N. Flausino Jr.