Oryzias carnaticus, (JERDON, 1849)

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 : 555-557

ORYZIAS CARNATICUS ( JERDON, 1849)

SPOTTED RICEFISH

FIGURES 25B , 39

Aplocheilus carnaticus Jerdon, 1849: 331 [type locality: India: Carnatic: river that passes by Waniambaddy (= Vaniyambadi); no drawings or type specimens].? Panchax cyanopthalma Blyth, 1858: 288 [type locality: India: Calcutta fish bazars; no figures or type specimens].? Panchax argenteus Day, 1868: 706 [type locality: India: Madras].- Whitehead & Talwar, 1976: species 174 in unnumbered table [list, notice of possible type specimens in Calcutta and London].- Ferraris, McGrouther & Parkinson, 2000: 294 [report of syntype catalogued as AMS B.7492, but not found].

? Haplochilus argenteus .- Day, 1873: cclxxvi [characters; Madras].

Oryzias melastigma . - Smith, 1938: 165–166 [classification].- Herre, 1939: 328, 331 [listed, distribution in Andaman Is., material].- Herre, 1941: 342 [listed as an accidentally introduced species in Andaman Is.].- Hubbs, 1941: 446 [comparison with Horaichthys setnai Kulkarni, 1940 ].- Ramaswami, 1946: 181–192 [osteological comparisons of skull with cyprinodontiform].- Kulkarni, 1948: 65–119 [comparative anatomy, osteology].- Rosen, 1964: 227 [classification in family Oryziatidae ].- Schrey, 1978: 335–338 [photograph, taxonomy of Oryzias ].- Uwa, Iwamatsu & Saxena, 1983: 43–47 [karyotype and cellular DNA content].- Sakaizumi, 1985: 521–522 [electrophoretic comparisons].- Uwa, 1986: 867–875 [cytogenetic comparisons].- Uwa & Parenti, 1988: 159 [morphometric and cytogenetic comparisons].- Rahman, 1989: 63 [listed from Bangladesh].- Pethiyagoda, 1991: 177–179 [distribution throughout Sri Lanka; photographs].- Talwar & Jhingran, 1991: 745–746 [characters and distribution, India, accidental introduction in Andaman Is.].- Hamaguchi, 1996: 757–763 [description and comparison of testis structure].- Seegers, 1997: 15, 20, 21 [listed, photographs].- Menon, 1999: 266 [listed from India].

Oryzias carnaticus .- Labhart, 1978: 53–54 [characters].- Schrey, 1978: 335 [taxonomy of Oryzias ].- Roberts, 1998: 217–218 [synonymy, characters, distribution].

Differential diagnosis: Oryzias carnaticus is a small Oryzias , in a group including O. dancena , O. haugiangensis and O. javanicus that share closed rather than open lacrimal sensory canals (as does O. hubbsi ) and a pelvic bone with a lateral strut that is needle-like and elongate, rather than blunt. Oryzias carnaticus , O. hubbsi , O. haugiangensis and O. javanicus have an enlarged, bilobed urogenital papilla in females. Oryzias carnaticus is like O. javanicus in having enlarged teeth posteriorly on the premaxilla of both sexes and a relatively posterior dorsal fin, and is distinct from O. javanicus in having an ethmoid cartilage anterior margin irregular and indented anteromedially, as opposed to straight, and lacking yellowish caudal fin margins in life.

Description: Small, maximum size of specimens examined 32.5 mm SL. Body compressed laterally, body depth 21–28. 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 relatively straight 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 24–28; snout length 6–8; eye moderate, 8–9, orbits meet dorsal surface of head. Basal portion of dorsal and anal fin project slightly beyond primary body profile. Scales relatively large, cycloid; 26–30 in a lateral series. Elongate, filamentous dorsal- and anal-fin rays in males; anal-fin rays with bony contact organs. Medialmost pelvic-fin ray connected to body via a membrane along its proximal portion. Caudal fin truncate. Male with short, tubular urogenital papilla; female with large, bilobed urogenital papilla.

Premaxilla short and broad with blunt ascending process; premaxilla and dentary with two irregular rows of caniniform teeth; males and females with two to four enlarged posterior teeth on the premaxilla, males with two to four enlarged teeth on dentary; tooth tips project through lips. No preethmoid cartilage; ossified portions of mesethmoid disc-shaped, suboval; 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 largely bone-enclosed and covered by epidermis. 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; elongate lateral process of pelvic bone attaches to or in line with third pleural rib. Caudal skeleton with two epural bones; one ventral accessory bone and one accessory cartilage. Fifth ceratobranchial toothplates subtriangular, with teeth in irregular rows anteriorly, followed by four discrete rows of unicuspid teeth, no small, incomplete posterior row. Basihyal bone triangular, basihyal cartilage extremely elongate and rectangular. Epibranchial elements fully ossified; epibranchial 2 absent.

Dorsal-fin rays 6–7. Anal-fin rays 21–24. Pelvic-fin rays 6. Pectoral-fin rays 11–13. Principal caudal-fin rays i,4/5,i. Procurrent fin-rays, dorsal 4, ventral 4–6. Vertebrae 28–30 (10–11 + 18–20). Branchiostegal rays 5.

Cytogenetic data: Probably reported in the literature as O. melastigma (see cytogenetic data for O. dancena , below).

Colour in life: Body translucent, and with melanophore pattern as described below in alcohol. Females with a subrectangular, males with a smaller, subtriangular silvery peritoneum and both sexes with a silvery operculum. Tips of elongate anal and dorsal fin rays of males whitish.

Colour in alcohol: A diffuse, faint row of melanophores from the dorsal surface of the head to the dorsal-fin origin, a midlateral black line from the head to base of the caudal fin that continues onto the caudal fin on the membrane just dorsal and ventral to the first ray above and below the midline, respectively. Females with a subrectangular, males with a smaller, subtriangular black peritoneum. A discrete black line along the anal-fin base. Dorsal and anal fin interradial membranes with scattered melanophores. Specimens from Orissa State, India, with relatively dense, small, dark brown chromatophores on dorsal surface of head and body. These may form small, discrete blotches, hence the common name spotted ricefish ( Seegers, 1997).

Distribution and habitat: Eastern India, Andaman Islands, Sri Lanka and Bangladesh in coastal brackish and freshwater habitats (herein and Roberts, 1998: 217–218).

Remarks: The original description of Aplocheilus carnaticus concludes ( Jerdon, 1849: 331): ‘I procured specimens of this minute fish in the river that passes by Waniambaddy in the Carnatic. It is very nearly allied in form, number of rays, etc. to A. Melastigma McL., but that is said not to exceed an inch in length, and, being from Calcutta, is probably distinct.’ Jerdon’s species was considered a synonym of O. melastigma , here O. dancena , following ( Roberts, 1998), by most authors until Labhart (1978) briefly differentiated the two species, primarily on colour pattern. I treat Aplocheilus carnaticus Jerdon, 1849 as a distinct species following Labhart (1978) and Roberts (1998). As for Oryzias dancena , below, it is nearly impossible, without voucher specimens or illustrations, to determine whether citations for O. melastigma refer to material that would now be identified as O. carnaticus or O. dancena .

Identification and origin of the ricefish species on the Andaman Islands has been uncertain. No ricefishes were listed by Day (1871) in an early account of fishes from the Andamans. Over 70 years later in his list of fishes from the Andaman Islands, Herre (1941: 342) referred to a lot of seven specimens, now CAS-SU 37089, as Oryzias melastigma , and concluded that they represented ‘no doubt an accidentally introduced species’. One specimen was subsequently separated from the rest of those in CAS-SU 37089 and placed in a vial along with a hand-written note that reads ‘ HOLOTYPE OF Oryzias herrei Myers (n. sp.)’, a name that was never published. The handwriting matches that of the late George S. Myers, Stanford University. Localities reported by Herre (1939: 331) for the specimens he examined in part match those of the CAS-SU material, below, although Herre did not report collector or date of collection other than that the specimens were sent to him by the Zoological Survey of India. Talwar & Jhingran (1991: 746) reported that O. melastigma was introduced accidentally into the Andamans along with Rohu ( Labeo spp. ) fry. I examined material from the Andaman Islands, below, and conclude that it agrees well with O. carnaticus in having, for example, 12 pectoral-fin rays rather than 10 or 11 as in O. dancena and O. javanicus .

Meristic data and information in the species synonymy are supplemented by those in Roberts (1998). Another common name for this species is spotted medaka ( Seegers, 1997: 20).

Material examined: 513 specimens (5–32.5 mm SL).

INDIA. Port Okha : N. side of Okha Pt., USNM 246914 , 10 (5–16.5 mm), ANTON BRUUN, 9.iii.1963 ; Orissa: freshwater streams 1–2 km inland along coast between Konark and Puri, CAS 60738, 28 (6.4– 27.7 mm), T. R. Roberts, 28.ii.1985 . Madras : CAS-SU 41531 , 5 (12.4–26.6 mm), A. W. Herre, 4.i.1941 .

Andaman Islands , South Andaman , Port Blair , creek N of South Corbyn’s Cove, CAS-SU 37089 , 7 (20.0– 32.5 mm, one female, 26.5 mm, of which has been cleared and counterstained), H. S. Rao, 15.ii.1935. South Andaman, no specified locality, CAS-SU 37088 , 19 (9.5–28.5 mm), H. S. Rao, 1 Dec 1934. North Andaman, from a shallow stream near base camp, CAS-SU 35658 , 2 (18.8–20 mm) .

SRI LANKA. Trincomalee , estuaries 1.5 mi. NW of Mahaweli R., western mouth, western side of road, USNM 313915 , 120 (7.2–26.4 mm), C. C. Koenig, 9.iv.1970 ; Akurala, SW coast, flooded pits under tidal influence, AMNH 20650 , 59 (11.8–26.5 mm, 5 of which have been cleared and stained solely with alizarin, 6 of which have been cleared and counterstained, and 1 male of which has been triple stained), R. Jonklaas, 21.iv.1965 .

BANGLADESH. Ganges Basin : Sundarbans : Karamjol Creek , large, strongly tidal creek about 5.5 km down Passur R. from Mongla, CAS 92307, 234 (11.6–25.0 mm, 12 of which have been cleared and stained, 4 of which have been cleared and counterstained), T. R. Roberts, 21.v.1996 ; large, strongly tidal creek on right side of Passur R. about 15–20 km downstream from Mongla, CAS 92308, 25 (18.7– 26.7 mm), T. R. Roberts, 22.v.1996 ; first large tidal stream on road from Cox Bazar to Tek Naf, CAS 92616, 4 (9.2–12.5 mm), T. R. Roberts & M. N. Sarker, 5 Jun 1996 .

Figures

Figure 25. A, Oryzias matanensis, CMK 6195, male, 42.5 mm SL; B, Oryzias carnaticus, CAS 37089, female, 26.5 mm SL. Diagrammatic representation of the dorsal portion of the gill arches. Scale bar = 1 mm.

Figure 39. Oryzias carnaticus (Jerdon, 1849), Trincomalee, Sri Lanka, AMNH 20650, male, 26.5 mm SL.