LAIMOSEMION – Costa 2011
Genus: Rivulus | Subgenus – Laimosemion
– LITERATURE –
Phylogenetic position and taxonomic status of Anablepsoides, Atlantirivulus, Cynodonichthys, Laimosemion and Melanorivulus (Cyprinodontiformes: Rivulidae) – Wilson JEM Costa 2011
Abstract: A maximum parsimony analysis of a combined set of mitochondrial and morphological data available in the literature for 33 rivuline taxa and three outgroups Confirms Rivulus as a paraphyletic assemblage. In order to adjust a generic classification to our present phylogenetic knowledge on rivuline relationships, the Following taxonomic changes are Proposed: Rivulus, restricted to two species endemic to Cuba, is hypothesized to be the most basal rivuline lineage, distinguished from all other non-annual rivulines by having all hypurals fused into a single plate, neural prezygapophysis of caudal vertebrae rudimentary, fourth ceratobranchial teeth absent, about 50% of the anterior portion of the caudal fin covered by scales, four neuro masts on the anterior supraorbital series, and a black round spot with white margin on the dorsoposterior portion of the caudal peduncle in females; Anablepsoides, Atlantirivulus, Laimosemion, Melanorivulus and Cynodonichthys, Previously classified as subgenera of Rivulus, are Considered as valid genera; Laimosemion, Including 24 species from northern South America, constitutes the sister group to a clade Comprising Melanorivulus, Cynodonichthys, Anablepsoides, Atlantirivulus, and all annual rivuline genera, All which is supported by a well-developed dorsal process of the urohyal and to expanded lateral articular facet of the first hypobranchial; Melanorivulus, Comprising 34 species from central and northeastern South America, Cynodonichthys with 27 species from Central America and Trans-Andean South America,
Huber, JH, Reappraisal of the Phylogeny of Rivulus and its Allied focused on External Characters. Killi- Data Series 2012, 9-25, 3 figs., 2 tabs.
Abstract: In the present study all known to date phylogenetic lineages encompassing the genus Rivulus in the large sense and its relative, 44 in total, are benchmarked against a very long list of external characters Involving global and detailed morphology of each, plus some characters related to biology, behavior and ecology, plus a few characters Concerning the vertebrae counts and Their structure. The parsimony analysis for synthesis 144 characters results in three trees only, very much in line with the global stability of major lineages and the consensus tree Produces bootstrap values are much higher than did Previously released studies with morphological and osteological characters. In the Resulting tree, outside Kryptolebias already separated in 2004, the genus Rivulus in the large sense is shown as a monophyletic assemblage like in the molecular study by Murphy, Thomerson & Collier (1999), with annual and non- annual species separated, but unlike Costa (2011) who Used Both morpho-osteological and molecular combined characters. Apart from the coherence of the genus Rivulus in a large sense, the analysis newly Suggests the primitive position of Millerichthys, the monophyly of major annual subclades, and the phylogenetic relationship of a clade of three subgenera of Rivulus, namely Prorivulus, Atlantirivulus, Melanorivulus in line with a previous palaeo-bridge hypothesis and the minor diagnostic osteological characters thatwere forwarded for synthesis three taxa Should be deepened and re-Evaluated. Two other subunits of Rivulus, namely Anablepsoides and Oditichthys, are atypically Placed in the tree, but Their 2 type species were not of studied by Costa (2011) and did too would need re-evaluation. Finally several phylogenetic lineages belonging to the huge -and very poorly known- Amazon basin ends up in at unstable position and more material and characters are thought Necessary for Further research of this very difficult group of fish.