A new subfamily of miniature loricariid catfishes have been named in a study of the molecular phylogeny of the Hypoptopomatinae and Neoplecostominae published in the most recent issue of the journal Molecular Phylogenetics and Evolution.
Mrcio Chiachio, Claudio Oliveira and Juan Montoya-Burgos studied the phylogeny of the group using a partial sequence of the nuclear F-reticulon4 gene.
The authors show that the Neoplecostominae is nested within the Hypoptopomatinae, and is the sister group to the group formerly known as the tribe Otothyrini.
Based on their results and morphological evidence, the authors erect the new subfamily Otothyrinae whose members include Corumbataia, Epactionotus, Eurycheilichthys, Hisonotus, Microlepidogaster, Otothyris, Otothyropsis, Parotocinclus, Pseudotothyris, and Schizolecis.
The membership of the Hypoptopmatinae is also modified to consist of Acestridium, Hypoptopoma, Nannoptopoma, Otocinclus and Oxyropsis, while the Neoplecostominae is modified to include Pseudotocinclus (in addition to Isbrueckerichthys, Neoplecostomus, Pareiorhaphis and Pareiorhina).
The authors also consider Nannoptopoma to be a junior synonym of Hypoptopoma based on their results.
The study also examines the historical biogeography of the group, with markedly few instances of dispersal across the border separating the Amazon basin and the Paran-Paraguay + eastern coastal Brazil + Uruguay being reconstructed.
The authors hypothesize that this may be due to several factors: (i) divergent ecological specialization; (ii) small body size of most members that limit dispersal due to body size-related effects; (iii) the strong pectoral armour possibly being a heavy handicap for dispersing via open waters.
For more information, see the paper: Chiachio, MC, C Oliveira and JI Montoya-Burgos (2008) Molecular systematic and historical biogeography of the armored Neotropical catfishes Hypoptopomatinae and Neoplecostominae (Siluriformes: Loricariidae). Molecular Phylogenetics and Evolution 49, pp. 606"617.