A new species has been described from the South American dwarf cichlid genus Dicrossus. Dicrossus gladicauda is so-named due to the filamentous extension on the upper lobe of the caudal fin. This feature also helps to distinguish it from D. filamentosus and D. maculatus . In D. filamentosus, the fin extensions are present on both caudal lobes while D. maculatus does not possess any extensions at all. Differences in caudal fin morphology also help distinguish it from two undescribed species thought to be of the same genus and currently named D. sp. "Rio Negro" and D. sp. " Tapajos". Here we go then:
It is described from the lower Rio Atabapo drainage in Colombia and is also supposed to be found in the vicinity of Rio Reita near Cumaribom, Puerto Gaitan in Venezuela. This small tributary of the Rio Tomo eventually empties into the Rio Orinoco.
Water parameters at the type locality: blackwater pH 4.4, conductivity 10 μS, hardness < 1dH temperature 24.4°C. Shallow water between 10-50 cm deep. Lots of leaf litter. Sympatric species: Hemigrammus bleheri, Hyphessobrycon stictus, Nannostomus eques, Paracheirodon axelrodi, Copella meinkeni, Apistogramma uaupesi.
The info and pictures are taken from Schindler, I. and Staeck, W. "Dicrossus gladicauda sp. n - a new species of crenicarinae dwarf cichlids (Teleostei: Perciformes: Cichlidae) from Colombia, South America." Vertebrate Zoology 58 (1) 2008 67-73. Thanks also to Mad Scientist over at Petfrd. /smile.gif" style="vertical-align:middle" emoid=":)" border="0" alt="smile.gif" />
I would've thought it would be more likely to be related to sexual selection ie. mate choice than a defence mechanism mate. I know that experiments with various species of Xiphophorus have shown that given the choice females will tend to choose a male with a sword, even if those of their own species don't have them. Could be something similar?
April 4, 2008
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