Oryzias, Parenti, 2008

Parenti, Lynne R., 2008, A phylogenetic analysis and taxonomic revision of ricefishes, Oryzias and relatives (Beloniformes, Adrianichthyidae), Zoological Journal of the Linnean Society 154 (3), pp. 494-610 : 550

GENUS ORYZIAS JORDAN & SNYDER, 1906

Oryzias Jordan & Snyder, 1906: 289 [type species:

Poecilia latipes Temminck & Schlegel, 1846 , by original designation and monotypy. Gender masculine].

Xenopoecilus Regan, 1911a: 374 [type species: Haplochilus sarasinorum Popta, 1905 , by monotypy. Gender masculine].

Horaichthys Kulkarni, 1940: 385 [type species: Horaichthys setnai Kulkarni, 1940 , by original designation and monotypy. Gender masculine].

Diagnosis: Oryzias is diagnosed as monophyletic by eight synapomorphies: small size at hatching, 4.5 mm or less; maximum adult body size less than 60 mm SL; hyomandibula with a single head articulating with otic region of skull; ventral hypohyal with a blunt posterior ramus; epibranchial 2 notably smaller than other epibranchial bones, lacking a broad point of articulation with the ceratobranchial cartilage, and cartilaginous or absent in some specimens; ceratobranchial bone 5 toothplate rectangular or suboval; fifth ceratobranchial teeth are arranged in horizontal rows; and total vertebrae number 34 or fewer. An additional character, small egg, is included tentatively as a ninth synapomorphy, although data for most ricefish species are lacking.

Distribution and conservation status: Naturally broadly distributed in fresh and brackish waters from the Indian subcontinent through continental and insular Asia, including Hainan Island, China, the Japanese Archipelago, Taiwan, and Luzon, the Philippines, the Malay Peninsula across the Indo- Malay-Philippines Archipelago as far east as Timor ( Fig. 2 ). Yamamoto (1975) indicated on a map that O. melastigma (probably O. dancena ) lives in Pakistan. I have examined no ricefish specimens from Pakistan. Furthermore, Jayaram (1981) does not give Pakistan as a locality for O. melastigma , and Mirza (1975, 1990) does not include ricefishes in his reports on freshwater fishes of Pakistan. Therefore, I am unable to confirm the natural occurrence of ricefishes in Pakistan. Oryzias latipes has apparently been introduced into Iran ( Coad, 1995) and New York, USA ( Hensley & Courtenay, 1980; see also Fuller, Nico & Williams, 1999). Oryzias populations are threatened or endangered throughout much of their natural range, especially in regions with relatively high human population density, such as Japan (K. Matsuura, pers. comm., 1999; Matsuura et al., 2000) and Taiwan ( Lin et al., 1999; Tzeng et al., 2006).

Remarks: Oryzias was considered a synonym of the cyprinodontiform killifish genus Aplocheilus by George S. Myers (1931) and collaborators (e.g. Herre & Myers, 1937), although the name Panchax was still used then for ricefishes (e.g. Fowler, 1938). Use of the names Aplocheilus , Panchax and Oryzias for groups of Asian killifish and ricefish species was reviewed by Smith (1938) who demonstrated that Panchax is an objective synonym of Aplocheilus , a cyprinodontiform (see also Myers, 1938: 137; Parenti, 1981: 351–352; Eschmeyer, 1990: 290). By 1955, Myers recognized (p. 7) the then cyprinodont ‘Subfamily Oryziatinae . The medakas. One genus: Oryzias , found from Japan to India.’

Figures

Figure 2. Approximate distributional limits of ricefishes, the family Adrianichthyidae, outlined and shaded. In the Philippines ricefishes are native only to the island of Luzon. Distribution throughout mainland China is estimated.