Oryzias marmoratus (Kottelat, 1990)

Herder, Fabian & Chapuis, Simone, 2010, Oryzias Hadiatyae, A New Species Of Ricefish (Atherinomorpha: Beloniformes: Adrianichthyidae) Endemic To Lake Masapi, Central Sulawesi, Indonesia, Raffles Bulletin of Zoology 58 (2), pp. 269-280 : 275

Notes on Oryzias marmoratus vs. O. profundicola .

– Oryzias marmoratus and O. profundicola show at least some overlap in diagnostic meristic and morphometric characters (dorsal and anal fin ray counts, relative body depth; Kottelat, 1990a). In contrast to Oryzias from L. Lontoa, which can clearly be assigned to O. marmoratus (Appendix 1), determination of sympatric O. marmoratus vs. O. profundicola in L. Towuti was accordingly not unequivocally straightforward in the sample we examined (see Appendix 2 for individual morphometric and meristic data). Two out of the six specimens examined in detail here show character states conflicting with a clear assignment to either of the two species, and determination of three additional individuals is based solely on anal fin ray counts. The same applies to pigmentation characters, which are—at least in preserved individuals—not unequivocally diagnostic in all specimens. Occasional hybridization ( Parenti, 2008) or early stages of divergence, in this case shallow-water dwelling O. marmoratus vs. clearly lacustrine O. profundicola , are among the most likely explanations for this phenomenon. Both are predicted for evolving radiations, and occur in another radiation of freshwater atherinomorph fishes in the Malili Lakes area ( Herder et al. 2006b, 2008; Schwarzer et al. 2008). Given the additional complexity due to significant geographic variation within O. marmoratus ( Kottelat, 1990a) , we stress that focus studies incorporating additional material will be required to solve this issue.