Oryzias dancena, (HAMILTON, 1822)

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 : 561-563

ORYZIAS DANCENA ( HAMILTON, 1822)

DEEP- BODIED RICEFISH

FIGURES 1 , 24F

Cyprinus dancena Hamilton, 1822: 342 , 393 [type locality ‘estuary below Calcutta;’ no type specimens, description based on unpublished drawing].

nec Aplocheilus melastigmus McClelland, 1839: 301 , 427, pl. 42, fig. 3a, b [type locality: India: ‘tanks in Calcutta’ ] .

Aplocheilus mcclellandi Bleeker, 1854: 323 [based on McClelland, 1839, pl. 55, fig. 4, as Hamilton’s lost figures of Cyprinus dancena , following Roberts, 1998).? Panchax cynaopthalma Blyth, 1858: 288 [type locality: India: Calcutta fish bazars; no figures or type specimens].

Aplocheilus MacClellandi Bleeker, 1860: 491 .

? 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 et al., 2000: 294 [report of syntype catalogued as AMS B.7492, but not found].

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

Haplochilus melastigmus .- Day, 1873: cclxxvi [characters; Calcutta and Myanmar (formerly Burma)].

Haplochilus melastigma .- Duncker, 1912: 249, 257– 258 [report from Sri Lanka].

Oryzias melastigma .- Smith, 1938: 165–166 [classification].- Hubbs, 1941: 446 [comparison with Horaichthys setnai Kulkarni, 1940 ].- Ramaswami, 1946: 181–192 [osteological comparisons of skull with cyprinodontiforms].- Kulkarni, 1948: 65–119 [comparative anatomy, osteology].- Rosen, 1964: 227 [classification in family Oryziatidae ].- Schrey, 1978: 335–338 [photograph, taxonomy of Oryzias ].- Uwa et al., 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].- Hamaguchi, 1996: 757–763 [description and comparison of testis structure].- Seegers, 1997: 15, 20, 21 [listed, photographs].- Menon, 1999: 266 [listed from India]. Panchax melastigma .- Munro, 1955: 85 [ Sri Lanka, characters].

Oryzias melanostigma .- Jayaram, 1981: 296 [ India, Bangladesh].

Oryzias dancena .- Roberts, 1998: 214–217, fig. 1 [new combination, synonymy, characters, distribution].- Albert et al., 1999: 650 [brain weight].- Parenti, 2000a: 2150 [listed].- Parenti, 2005: 24 [photograph]. Panchax cyanophthalmus .- Menon, 1999: 266 [as a synonym of Oryzias melastigma ( McClelland, 1839) ].

Differential diagnosis: Oryzias dancena is a small Oryzias , in a group including O. carnaticus , 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 needlelike and elongate, rather than blunt. Oryzias dancena is one of the most deep-bodied ricefishes, with body depth reaching 34% SL, vs. no more than 28% SL in other species in this group. In addition, O. dancena females have relatively moderate-sized, not greatly enlarged, bilobed urogenital papilla.

Description: Small, maximum size of specimens examined 30.7 mm SL. Body compressed laterally, deep bodied, body depth 24–34. 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 convex from head to anal-fin origin, particularly in larger specimens. Dorsal surface of head slightly convex just anterior to orbits. Head length 23–27; snout length 5–7; eye moderate, 7–8, orbits meet 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 relatively large, cycloid; 25–28 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 to slightly rounded. Male with a short, tubular urogenital papilla; female with moderate, slightly bilobed urogenital papilla.

Premaxilla short and broad with distinct ascending process; premaxilla and dentary with two irregular rows of caniniform teeth; males with two or three enlarged posterior teeth on the premaxilla and dentary; tooth tips project through lips. 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 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; lateral process of pelvic bone attaches to 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 six discrete rows of unicuspid teeth, including a small, incomplete posterior row. Basihyal bone relatively short and triangular, basihyal cartilage extremely elongate and rectangular. Epibranchial elements fully ossified; epibranchial 2 notably smaller than the other epibranchial elements.

Dorsal-fin rays 6–8. Anal-fin rays 19–24. Pelvic-fin rays 6. Pectoral-fin rays 10–11. Principal caudal-fin rays i,4–5/5,i. Procurrent fin-rays, dorsal 4, ventral 5. Vertebrae 28–29 (10–11 + 17–18). Branchiostegal rays 4–5.

Cytogenetic data: Oryzias dancena has a monoarmed chromosome constitution (Uwa, 1986, 1991b) and is characterized by having a diploid chromosome number of 48, comprising 24 acrocentric pairs, and a chromosome arm number of 48 ( Table 2). Genome size is recorded as 1.8 pg DNA per nucleus.

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.

Colour in alcohol: A discrete 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 faint black line along the anal-fin base. Dorsal and anal fin interradial membranes with scattered melanophores.

Distribution and habitat: India, Sri Lanka, Bangladesh and Myanmar in coastal brackish and freshwater habitats. Oryzias melastigma (probably O. dancena ) was reported from Pakistan by Yamamoto (1975) who did not cite any material. I know of no Oryzias specimens from Pakistan; Mirza (1975, 1990) did not include that genus in his lists of freshwater fishes of Pakistan.

Remarks: The first scientific description of a ricefish, identified as a minnow, family Cyprinidae , was not recognized until Roberts’s (1998: 214–217) investigation. McClelland’s (1839) type specimens of Aplocheilus melastigmus are apparently lost ( Uwa & Parenti, 1988). As for Oryzias carnaticus , above, 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. dancena or O. carnaticus . Meristic data and information in the synonymy are supplemented by that in Roberts (1998).

Material examined: 457 specimens (8.7–30.7 mm SL). INDIA. Chindambaram : CAS 60740, 4 (21.6– 23.0 mm), laboratory stock, O. P. Saxena, x.1981 ; CAS 58028, 71 (19.2- 26.0 mm, 5 of which have been cleared and counterstained), O. P. Saxena & T. Iwamatsu,. x.1981 ; Madras , CAS-SU 30562 , 11 (19.5– 25.7 mm), Madras Fisheries Dept., 4.iv.1934 ; Ganges Delta , ZMA 100.549 , 20 (11.4–22.9 mm), L. F. de Beaufort, 6.i.1938 ; Ganges Delta at Uttarbhag : CAS-SU 35653 , 63 (15.5–28.7 mm, 4 of which have been cleared and counterstained), A. W. Herre, iv.1937 ; Pulta, Bengal , CAS-SU 35654 , 1 (24.5 mm), A. W. Herre, 10.iv.1937 ; Orissa: Gopalpur, Ganjam Dist. , CAS-SU 41530 , 8 (18.5–30.7 mm), H. A. Hafiz, 26.i.1941 ; Pondicherry: USNM 86539 , 2 (26.5– 26.9 mm), E. Deschamps, xi.1901 ; Vishakhapatnam Harbor : USNM 246915 , 5 (23.9–26.3 mm), ANTON BRUUN, 13.iv.1963 , USNM 246916 , 78 (14.9– 27.4 mm), ANTON BRUUN, 12–14.iv.1963 .

SRI LANKA. Trincomalee : estuaries about 3 mi. N of Mahaweli River’s mouth, W side of road, USNM 247510 , 32 (13.2–29.6 mm), C. Koenig, 9.iv.1970 , N end of harbor, USNM 313916 , 11 (21.0– 27.9 mm), C. Koenig, 5.iv.1970 ; Jaffna area : Pasaioor village, USNM 313906 , 1 (19.7 mm), T. R. Roberts, 17.iii.1970 ; Colombo : Kelani R. about 1/ 4 mile from its mouth at village at Mattakuliya near Colombo, USNM 313908 , 47 (12.5–27.7 mm), T. R. Roberts, 12.iii.1970 ; north of Colombo , USNM 313913 , 1 (20 mm), T. R. Roberts, 14.iii.1970 . Vaddukkodai : Kakaithivu fish landing, about 3 mi S of Vaddukkodai, USNM 313910 , 37 (13.8–24.5 mm), T. R. Roberts, 17.iii.1970 ; Eastern Prov : Batticaloa Dist. Just S of Kallu at S end of causeway, USNM 313912 , 1 (13.9 mm), T. Iwamoto, 11.vi.1970 ; Nagombo Pt.: lagoon next to Pitipana fishery station, 2 mi S of Negombo Pt., USNM 313914 , 3 (20.7–22.0 mm), T. Iwamoto, 6.v.1970 . Munyal Lagoon : about 20 mi. S of Puttalam, USNM 313917 , 17 (8.7–18.8 mm), T. R. Roberts, 14.iii.1970 .

MYANMAR. Rangoon (= Yangon) Div ., Rangoon (= Yangon): BMNH 1911.8.14 : 18, 1 (28 mm, female), J. P Arnold , CAS-SU 69099 (ex. SU 40208 ), 2 (16.5– 22.8 mm), A. W. Herre, xi.1940 , Insein township at fisheries lab off BPI road, USNM 342156 , 39 (10– 24.5 mm, of which one male 24.5 mm, and one female 23.0 mm have been cleared and counterstained), C. J. Ferraris & D. Catania, 10.iv.1996 ; small tidal creek off Pazundung Cr., CAS 60737, 2 (12.0– 13.8 mm), T. R. Roberts, 10.iii.1985 .

Figures

Figure 1. Oryzias dancena (Hamilton, 1822), the first described ricefish species, USNM 313908, adult female, 23.8 mm SL, above; adult male, 25.0 mm SL, below. Sri Lanka. Female is carrying a cluster of embryos.

Figure 24. A, Hemirhamphodon kuekenthali, USNM 330828, adult male, 50 mm SL; B, Adrianichthys roseni, USNM 322425, adult female, 73 mm SL; C, Adrianichthys poptae, USNM 322423, adult female, 168 mm SL; D, Adrianichthys oophorus, USNM 348386, female, 60 mm SL; E, Oryzias bonneorum, ZMA 123.863, adult female, 40 mm SL; F, Oryzias dancena, USNM 342156, adult male, 24.5 mm SL. Diagrammatic representation of the hyoid bar. Arrows indicate posterior extent of the ramus of the ventral hypohyal. Beloniform fishes lack an interhyal. All drawn to same scale.