A new ricefish, Oryzias moramoensis (Adrianichthyidae), described from a mountain waterfall in Southeast Sulawesi, Indonesia

Oryzias moramoensis, a new species of ricefish (Adrianichthyidae), is described from Moramo Waterfall, Regency of Konawe Selatan, Southeast Sulawesi Province, Indonesia. The new species is a member of the Oryzias woworae species group, which is endemic to southeastern Sulawesi and is distinguished by a bluish sheen on the body in live males. Oryzias moramoensis sp. nov. is distinguished from other species of the Oryzias woworae species group (i.e., Oryzias asinua Parenti, Hadiaty, Lumbantobing and Herder 2013, Oryzias wolasi Parenti, Hadiaty, Lumbantobing and Herder 2013 and Oryzias woworae Parenti and Hadiaty 2010) by the combination of the following characters: 8 transverse scales; head length 26.6%–27.7% of standard length (SL) in males, and 28.0%–28.9% of SL in females; body depth at anal-fin origin 24.3%–28.2% of SL in males, and 23.5%–24.0% of SL in females; scarce or no pigmentation along the ventral and dorsal margins of caudal fin of males after preservation. Principal component analysis based on genome-wide single nucleotide polymorphisms revealed that O. moramoensis is clearly separated from the other three species along the first principal component. We discuss why O. moramoensis is genetically isolated from the other members of the species group despite their close geographic proximity.