The genus Llanolebias is described to accommodate the species originally described as Rivulus stellifer Thomerson & Turner, 1973, but currently referred to the genus Rachovia Myers, 1927. Rachovia stellifer has had a complicated taxonomic history and has, at various times since its description, been placed in and out of three genera: Rivulus Poey, 1860, Pituna
Costa, 1989 and Rachovia. However, phylogenetic analyses using 3537 mitochondrial and nuclear characters, and 93 morphological characters indicate it is not a member of any of these genera, but place it as a deeply divergent sister species to the genus Gnatholebias Costa, 1998. In addition to molecular characters, it is distinguished from the genera Rachovia and Gnatholebias by 13 and 33 morphological character states, respectively.

In the last three decades, several phylogenetic hypotheses have been proposed for the fish order Cyprinodontiformes, as well as for its taxonomic subsets. Parenti (1981) presented the first cladistic analysis of the Cyprinodontiformes, including an analysis of phylogenetic relationships of the South American family Rivulidae. Nearly 10 years later Costa (1990a) published a phylogeny focusing solely on the family Rivulidae. Costa (1990a) used data similar to those of Parenti (1981), but came to a startlingly different phylogenetic hypothesis. Among the major points of disagreement between Costa’s and Parenti’s phylogenies is the taxonomic placement of Rivulus stellifer Thomerson & Turner, 1973. While Parenti (1981) retains this annual species in the genus Rivulus Poey, 1860 as originally described by Thomerson and Turner (1973), Costa (1990b) places this species into the genus Pituna Costa, 1989 based on a set of shared derived characters. The other member
of the genus is Pituna poranga Costa, 1989 from the Cerrado region of the upper Araguaia River system of Brazil. Later, Costa (1998b) revises the genus Pituna, synonymizes P. poranga Costa, 1989 with the newly rediscovered Rivulus compactus Myers, 1927 which is transferred to the genus Pituna (P. poranga was subsequently removed from synonymy with P. compacta by Costa (2007)), and also removes Pituna stellifer from the genus Pituna, placing it back into the genus Rivulus, but suggesting that it might be related to the genera Rachovia Myers, 1927 and Austrofundulus Myers, 1932. A second major revision of the Rivulidae came with the publication of Costa’s (1998a) work, where he transfers R. stellifer to the genus Rachovia based on a new set of shared derived characters. Hrbek and Larson (1999) published a molecular phylogeny of the Rivulidae based on a 1972 nucleotide dataset of mitochondrial genes.

In this study, Rachovia stellifer is found to be the sister species to Gnatholebias
zonatus (Myers, 1935). Rachovia maculipinnis Radda, 1964, the other Rachovia species analyzed in Hrbek and Larson (1999) is strongly supported as the sister species of Austrofundulus limnaeus Schultz 1949.

These findings are reiterated by subsequent molecular studies of the Rivulidae (Hrbek et al., 2004; Vermeulen
& Hrbek, 2005). Recently Costa (2005) revised the genus Pterolebias Garman, 1895 using R. stellifer as one of the taxa in this taxonomic treatment. The new set of characters reported by Costa (2005) do not place R. stellifer sister to the species R. maculipinnis, a phylogenetic relationship expected if Rachovia were monophyletic. In addition to R. stellifer and R. maculipinnis, the genus Rachovia also contains the species R. brevis (Regan, 1912) (the type species), R. pyropunctata Taphorn & Thomerson, 1978 and R. hummelincki de Beaufort, 1940 species which with the exception of R. hummelincki were previously analyzed by Costa (1998a). In Costa (2005), R. stellifer is sister to a clade containing species of the genera Terranatos Taphorn & Thomerson, 1978, Rachovia, Austrofundulus and Pituna. The taxonomy and evolutionary history of R. stellifer is clearly complex, and remains unresolved. There are apparent conflicts between published analyses, however, without a rigorous statistical evaluation of these apparent conflicts, it is difficult to determine the source, or even if real conflicts exist. Earlier publications (Parenti, 1981; Costa, 1990a, 1998a) do not report a statistical assessment of the phylogenetic position of R. stellifer, while later publications (Hrbek & Larson, 1999; Hrbek et al., 2004; Costa, 2005; Vermeulen & Hrbek, 2005) show weak statistical support for the phylogenetic placement of R. stellifer. The goal of this study is the reanalysis of the phylogenetic position of R. stellifer. To achieve this goal, we analyzed a dataset composed of 3635 molecular characters approximately equally distributed between the evolutionarily independent nuclear and mitochondrial genomes, and 93 morphological characters obtained from Costa (2005).

Behavior:

The genus shows annual behaviour.