Tuesday, July 19, 2011

[Ichthyology • 2004] Adrianichthys roseni & Oryzias nebulosus, 2 new ricefishes (Adrianichthyidae) from Lake Poso, Sulawesi, Indonesia

Fig. 5. Oryzias nebulosus sp. nov., Lake Poso, Sulawesi Tengah, Indonesia, MZB 11649, holotype, male, 32.5 mm SL

Oryzias nebulosus sp. nov.
(English name: nebulous ricefish)

Two new species of ricefishes or buntingi, Adrianichthys roseni and Oryzias nebulosus, are described from Lake Poso, Sulawesi Tengah, Indonesia, bringing to 12 the number of endemic ricefishes known from Sulawesi. Adrianichthys roseni and its sole congener, A. kruyti, are distinguished from other relatively large-bodied ricefishes, Xenopoecilus, in having orbits that project beyond the dorsal profile of the head; paired preethmoid cartilages (versus single or absent in Xenopoecilus); and 13–16 (versus 8–13) dorsal fin rays. Also, as in A. kruyti, the lower jaw of A. roseni is enclosed in the upper jaw when the mouth is closed; however, the upper jaw is not as large and broadly expanded as in A. kruyti. Adrianichthys roseni differs further from A. kruyti in having fewer scales in a lateral series (approximately 63–65 versus 70–75), attaining a smaller maximum recorded standard length (90 mm versus 109 mm), and having the lateral process of the pelvic bone in line with the fifth, rather than the eighth, pleural rib. Oryzias nebulosus shares with O. nigrimas, also from Lake Poso, a unique sexual dichromatism in preserved specimens: adult males are dark gray to black, whereas females are a lighter grayishyellow to brown. Relative to O. nigrimas, O. nebulosus is a small species (maximum recorded SL 33 mm versus 51 mm), with pelvic fins relatively anterior (lateral process of pelvic bone is in line with the third, fourth, or fifth, modally fourth, rather than the fourth or fifth, modally fifth, pleural rib), dorsal fin relatively anterior (origin above the 12–14th anal fin ray as opposed to the 15–17th anal fin ray), precaudal vertebrae 11–13, modally 12 (versus 13–14, modally 13), and relatively straight, narrow and slender (as opposed to curved, broad, and robust) ossified and cartilaginous portions of the gill arches. Endemic buntingi are threatened by introduction of exotic species, overfishing, and pollution. A conservation plan includes rearing native fishes for local use as ornamental fishes and possible reintroduction.

Key words: Ricefishes · Sulawesi · Buntingi · Adrianichthys roseni sp. nov. · Oryzias nebulosus sp. nov

Oryzias nebulosus sp. nov.
(English name: nebulous ricefish)
Holotype. MZB 11649, adult male, 32.5 mm SL. Lake Poso at Peura, eastern shore of lake approx. 10 km S of Tentena, Sulawesi Tengah, Indonesia, collected by L.R. Parenti, K.D. Louie, P. Beta, et al., 13 August 1995.
Etymology. The specific name nebulosus, misty or foggy, to connote a species previously unrecognized among the melanistic Oryzias in Lake Poso.

Fig. 2. Adrianichthys roseni sp. nov., Lake Poso, Sulawesi Tengah, Indonesia, MZB 6732 (ex. USNM 322424), holotype, female, 90 mm SL

Adrianichthys roseni sp. nov.
(English name: Rosen’s buntingi)

Adrianichthys kruyti (not of Weber); Rosen and Parenti, 1981: 16, Fig. 15b (Lake Poso, dorsal gill arch osteology); Parenti, 1989:80, Fig. 1 (Lake Poso, photo).
Holotype. MZB 6732 (ex. USNM 322424), gravid female, 90 mm SL, Lake Poso, Sulawesi Tengah, Indonesia, 4–5 September 1978, collected by N.J. Wilimovsky.
Paratype. USNM 322425, cleared and counterstained female, 73 mm SL, collected with the holotype.
Etymology. The specific name, roseni, honors the late Donn E. Rosen, in recognition of his enthusiasm, generosity, and enduring contributions to atherinomorph systematics.

Fig. 1. Map of Sulawesi, Indonesia, indicating type localities of the 12 endemic adrianichthyid species. Lake Poso, 7 endemics: Adrianichthys kruyti, Xenopoecilus oophorus, X. poptae, A. roseni sp. nov., O. nigrimas, O. nebulosus sp. nov., O. orthognathus; SW Sulawesi (Ujung Pandang), 1 endemic: Oryzias celebensis; Malili Lakes, 3 endemics: O.marmoratus, O. matanensis, O. profundicola; and Lake Lindu, 1 endemic: Xenopoecilus sarasinorum

Table 1. Ricefishes or buntingi, family Adrianichthyidae, known from Sulawesi

Parenti, L. R., and B. Soeroto. 2004. Adrianichthys roseni and Oryzias nebulosus, two new ricefishes (Atherinomorpha: Beloniformes: Adrianichthyidae) from Lake Poso, Sulawesi, Indonesia. Ichthyological Research. 51:10–19.: http://si-pddr.si.edu/dspace/handle/10088/10952