When Stauffer et al. erected the genus Metriaclima in 1997 they gave no indication of the gender of the new taxon. This omission has gone unremarked...until now!
This is probably because all but one of the included species had names that were genitives (eg M. estherae, M. lombardoi) or nouns in apposition (eg M. zebra, M. callainos), neither of which are affected by the gender of the genus. Only adjectival species names are required to agree in gender with their genus.
However, the recent description of five new species of Metriaclima by Cicotto et al. has now given rise to the question of gender, as two of the new names are adjectives.
The authors described these species as M. mossambicus and M. nkhunguensis, ie masculine, and Fishbase lists them as such. Meanwhile Eschmeyer’s online Catalogue of Fishes has the genus as feminine, perhaps because it ends in –a, often a feminine ending in Latin. So the two main authorities on such things disagree. Ad Konings (pers. comm.), one of the authors of the recent paper, has stated that he thought Stauffer intended the genus to be masculine.
But it isn’t always as simple as what an author intends! The International Code of Zoological Nomenclature lays down strict rules for the creation of scientific names in the animal kingdom. The original description of the genus states that Metriaclima is a compound noun created from the Greek words metrios (= moderate) and klima (= slope, Latinised to clima) and refers to the angle of the upper head profile. The Code states that in such cases the final part of the name – in this case -clima - determines the gender of the genus, which must be the gender of the original "root" noun.
A quick check of the Greek dictionary reveals that klima is neuter, and hence so must be Metriaclima. This in turn means that the new species should in fact be M. mossambicum and M. nkhunguense. The only other species affected is M. cyneusmarginatus, which now becomes M. cyneusmarginatum.
The situation was first brought to light by German authors Kurt Dreimätz and Erwin Schraml in the online journal eggspots, and has been reported to Jay Stauffer, who it is hoped will formally rectify it in due course.
For further information see: Dreimätz, K. F. (2011) Five additional Metriaclima species described. eggspots 5: 25-30. www.worldfish.de.