Oryzias marmoratus, (AURICH, 1935)

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 : 569-571

ORYZIAS MARMORATUS ( AURICH, 1935)

MARMORATED RICEFISH

FIGURE 45

Aplocheilus marmoratus Aurich, 1935: 102–104 , fig. 1b [type locality: Indonesia: Sulawesi, small rivulets flowing into lake at Lingkoburanga, Lake Towoeti [ Towuti ]].

Oryzias marmoratus .- Yamamoto, 1975: 24 [listed].- Schrey, 1978: 334–338 [photograph, taxonomy of Oryzias ].- Whitten et al., 1987a: 295, table 4.10 [Sulawesi, distribution].- Whitten et al., 1987b: 43–48, table 1 [Sulawesi, conservation].- Kottelat, 1989b: 682, fig. 11 [report from Lake Towuti].- Kottelat, 1990b: 155–159, figs 2–5, tables 3–5 [redescription, comparisons].- Kottelat et al., 1993: 90 [listed; characters].- Naruse et al., 1994: 49 [cytogenetic data].- Hamaguchi, 1996: 757–763 [description and comparison of testis structure].- Seegers, 1997: 15, 20 [listed, photograph].- Albert et al., 1999: 650 [brain weight].

Differential diagnosis: The Malili Lakes buntingi of Sulawesi, O. marmoratus , O. profundicola and O. matanensis , are readily distinguished from all other ricefishes by their distinctive pigmentation pattern: males have a series of regular midlateral brown to black blotches and irregular dark brown blotches over the entire lateral surface of the body. They are all somewhat deep bodied, reaching more than 26% SL; have a relatively large eye, diameter reaching 10% or more of SL; and have relatively long anal fins that range to over 24 anal-fin rays. Oryzias marmoratus is further distinguished by the live colour pattern of adult males: head and body greyish-brown with diffuse, dark brown blotches distributed irregularly on the body, and a row of five to nine larger blotches irregularly distributed dorsal to the midaxial stripe; there is a proximal row of dark purple to black spots on the membranes between anal-fin rays, and the posterior half of anal-fin margin is black. Oryzias marmoratus and O. matanensis have 8–12 and 8–9 dorsal-fin rays, respectively, whereas O. profundicola has 10–14. Oryzias marmoratus and O. profundicola have 31–32 or 32–34 scales in a lateral series, respectively, whereas O. matanensis has 41–47.

Description: Intermediate, maximum size of specimens examined 40.2 mm SL. Body compressed laterally, moderately deep, body depth 25–30. No pronounced abdominal concavity between pelvic fins and anal fin. Mouth terminal, jaws subequal or lower jaw projecting slightly beyond upper jaw. Dorsal body profile arching gently from head to dorsal-fin origin; ventral body profile somewhat convex from head to anal-fin origin. Dorsal surface of head slightly convex just anterior to orbits. Head length 24–27; snout length 7–9; eye large, 10–12, orbits do not project beyond dorsal surface of head. Single-lobed testis on right side of body of males. Basal portion of dorsal and anal fin do not project significantly beyond primary body profile. Scales of moderate size, cycloid, and somewhat deciduous; 31–32 in a lateral series. Elongate, slightly filamentous dorsal- and anal-fin rays in males; anal-fin rays without bony contact organs. Medialmost pelvic-fin ray connected to body via a membrane along its proximal half in males, along its entire length in females. Caudal fin truncate. Male with a short, slightly conical, tubular urogenital papilla; female with bilobed urogenital papilla.

Premaxilla short and broad with distinct ascending process; premaxilla and dentary with two irregular rows of caniniform teeth in irregular rows up to seven teeth deep, although the closely packed teeth of males makes these counts imprecise; males with two to three rows of external conical teeth on the upper and lower oral jaws, and thick and fleshy lips through which just the tooth tips project. No preethmoid cartilage; ossified portions of mesethmoid disc-shaped; anterior border of ethmoid cartilage irregular. No flanges on the ventral surface of the palatine and the quadrate. Dorsal ramus of hyomandibula not distinctly bifid, single cartilage articulates with sphenotic and pterotic. Lacrimal sensory canal carried in open bony groove. First pleural rib on parapophysis of third vertebra; first epipleural bone attaches to parapophysis of first vertebra dorsal to, and not in horizontal line with, posterior epipleural bones; lateral process of pelvic bone attaches to third pleural rib. Caudal skeleton with two epural bones; one ventral accessory bone. Fifth ceratobranchial toothplates subtriangular, with teeth in irregular rows anteriorly, followed by eight discrete rows of unicuspid teeth, including a small, incomplete posterior row. Basihyal bone triangular, basihyal cartilage extremely elongate and rectangular. Epibranchial elements fully ossified; epibranchial 2 notably smaller than the other epibranchial elements.

Dorsal-fin rays 8–12. Anal-fin rays 20–26. Pelvic-fin rays 6. Pectoral-fin rays 10. Principal caudal-fin rays i,4/5,i. Procurrent fin-rays, dorsal 5, ventral 6. Vertebrae 30 (12 + 18). Branchiostegal rays 5.

Cytogenetic data: Oryzias marmoratus has a fused chromosome constitution with 2 n = 42 chromosomes ( Table 2; Naruse et al., 1994).

Colour in life: (From Kottelat, 1990b: 156): Males greyish-brown on head and body. Diffuse dark brown blotches dispersed on body, including a row of five to nine larger blotches dorsal to midaxial stripe. Eyes blue. Filamentous dorsal-fin rays yellow or hyaline, distal margin of dorsal-fin black. Dorsal and ventral margin of caudal fin bright yellow; two to four longitudinal dark purple stripes on proximal half of membranes between median caudal-fin rays. A proximal row of dark purple to black spots on the membranes between anal-fin rays; posterior half of anal fin with a black margin. Pelvic fin bright yellow; pectoral fin hyaline.

Colour in alcohol: Ground colour yellowish-grey. Dorsal surface of head and dorsal and lateral surface of body with dense dark brown to black chromatophores. A discrete row of melanophores from dorsal surface of head to dorsal-fin origin, an interrupted midlateral black line from head to base of caudal fin. Females with diffuse line of dark chromatophores from a point just posterior to anal-fin origin, along body just dorsal to anal-fin base to middle of caudal peduncle. Fins of females and pectoral and pelvic fins of males hyaline to dusky. Urogenital papilla of females and of males immaculate or with several melanophores. Dorsal- and anal-fin rays of males dusky except at their margins which are hyaline. A proximal row of black spots on membranes between anal-fin rays; posterior half of anal fin with a black margin. Caudal fin-rays of males dusky, a dark line along proximal half of membrane between median caudal-fin rays.

Distribution and habitat: Endemic to lakes of the Malili River basin, Sulawesi Selatan, Indonesia: lakes Towuti, Wawontoa and Mahalona ( Parenti & Soeroto, 2004: fig. 1). Found in creeks, streams and rice paddies along the lakeshore ( Kottelat, 1990a).

Remarks: A neotype for Oryzias marmoratus (ZSM 27172, now ZRC 38449) was designated by Kottelat (1990b: 155) from material he collected in 1988 from Lake Towuti, after concluding that the 22 syntypes from lakes Towuti and Mahalona were lost or destroyed. A neotype was designated because Kottelat (1990b) recognized variation among populations from lakes Towuti, Wawontoa and Mahalona and acknowledged that material he identified as O. marmoratus (Aurich) may include more than one species and possible hybrids with O. profundicola Kottelat (1990b) . I base my diagnosis and description of Oryzias marmoratus on data on the neotype (from Kottelat, 1990b), which I did not examine, and other specimens from the restricted type locality. Data were augmented by those in Kottelat (1990b). Another common name for this species is marmorated medaka ( Seegers, 1997: 20).

Material examined: 546 specimens (10.2–40.2 mm SL).

INDONESIA. Sulawesi Selatan: Lake Towuti, small rivulets flowing into the lake on a sandy beach at Lingkoburanga , about 6 km S of Timampu, type locality, ZSM/LIPI 7 , 8 (13.0– 35.5 mm), and CMK 6381 (ex. CMK 6222 ), 1 (adult female, 36.5 mm, counterstained), M. Kottelat, 22.vi.1988 ; Sg. Lingkoburanga where it enters Lake Towuti , approx. 8 km S of Timampu, USNM 348528 , 24 (13.4– 40.2 mm), L. R. Parenti, K. D. Louie & P. Haji, 9.viii.1995 . First stream just S of Sg. Lingkoburanga, where stream enters Lake Towuti , USNM 348574 , 8 (20.6–26.5 mm), L. R. Parenti, K. D. Louie & P. Haji, 9.viii.1995 . Lake Mahalona, Sg. Tombalala where it enters on SW shore of Lake Mahalona , USNM 348529 , 505 (10.2–35.1 mm, 10 of which have been cleared and counterstained), L. R. Parenti, K. D. Louie, P. Haji & T. Amos, 8.viii.1995 .

Figures

Figure 45. Oryzias marmoratus (Aurich, 1935), Lake Towuti, Sulawesi Selatan, Indonesia, ZSM/LIPI 7, male, 34.7 mm SL, above, female, 33 mm SL, below.