The taxonomy of the South American killifish genus Leptolebias has been the subject of a detailed study by Brazilian killifish expert Wilson Costa.
Costa's study, which is published in the most recent issue of the Zoological Journal of the Linnean Society, recognizes that Leptolebias is not monophyletic, and described a new genus, Notholebias, for three species formerly placed in Leptolebias: L. minimus, L. fractifasciatus, and L. cruzi.
He also describes a new species, Leptolebias itanhaensis, from the coastal plains of So Paulo, in southern Brazil.
NotholebiasBasing his study of the phylogeny of Leptolebias on 58 morphological and behavioural characters, Costa found the three species of Leptolebias to be more closely related to a group consisting of Campellolebias, Cynopoecilus and other Leptolebias than to all other Leptolebias.
The new genus is named after the superficial resemblance of its members to the African killifish genus Nothobranchius.
Leptolebias itanhaensisThis new species is distinguished from all other members of the genus except L. aureoguttatus in having four (vs. two) caudal neuromasts, and the presence (vs. absence) of horizontal golden lines on the caudal fin in males.
It differs from L. aureoguttatus in having the two dark-red stripes on the dorsal and ventral submarginal portion of caudal restricted to the anterior portion of the fin (vs. along entire fin) in males, the caudal-fin stripes in males parallel to the fin rays and not branching posteriorly (vs. branching posteriorly), the basal portion of the dorsal fin with small dark orange spots in males (vs. dark red to dark brown short transverse bars), and five or six (vs. three or four) lateral mandibular neuromasts. Leptolebias itanhaensis is also distinguished from all congeners in having more caudal-fin rays (27"31 vs. 25"28).
The new species is named after its type locality (where it is only known), the Itanham River drainage, an isolated small coastal drainage in southeastern Brazil.
According to the author, Leptolebias itanhaensis is found in ...shallow (about 10"40-cm deep), temporary channels within dense rainforest, in tea-coloured and acidic (pH 3.5"4.0) water that contains litter at the bottom.
A total of six species of Leptolebias (including L. itanhaensis) are recognized in this study: L. marmoratus, L. splendens, L. opalescens, and L. citrinipinnis (all four from the coastal plains of Rio de Janeiro), and L. aureoguttatus (which is also redescribed in this study) from the coastal plains of So Paulo and Paran.
No images of the fish were available for publication.
For more information, see the paper: Costa, WJEM (2008) Monophyly and taxonomy of the Neotropical seasonal killifish genus Leptolebias (Teleostei: Aplocheiloidei: Rivulidae), with the description of a new genus. Zoological Journal of the Linnean Society 153, pp. 147"160.