Oryzias setnai 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 : 585-587

ORYZIAS SETNAI ( KULKARNI, 1940) COMB. NOV.

ANU

FIGURES 16B , 20A , 21, 26A , 27B , 55

Horaichthys setnai Kulkarni, 1940: 385–421 , figs 2– 20 [type locality: Navlaki, Kathiawar coast, north and south of Bombay, India].- Hubbs, 1941: 446–447 [characters, relationships].- Hubbs & Hubbs, 1945: 289–295, table XIX [bilateral asymmetry].- Kulkarni, 1948: 65–119 [comparative anatomy, osteology].- Silas, 1959: 256 [distribution].- Rosen & Bailey, 1963: fig. 3d, 28 [skull, comparison with poeciliid Tomeurus ].- Rosen, 1964 [comparative anatomy, classification].- Menon & Yazdani, 1968: 141 [syntypes listed].- Rosen & Parenti, 1981: 6–16, fig. 15a [dorsal gill arch osteology].- Grier, 1984: 833–839 [testis structure, spermatophore formation].- Parenti, 1987: 561 [characters, comparisons].- Grier & Collette, 1987: 309–311 [comparison of spermatophore formation with that of Zenarchopterus ].- Talwar & Jhingran, 1991: 746–747 [characters, distribution].- Parenti, 1993: 190, fig. 10 [caudal skeleton].- Menon, 1999: 267 [listed from India, citations].- Parenti & Grier, 2004: 336 [atherinomorph testis type, listed].

Differential diagnosis: Oryzias setnai is a highly autapomorphic species, distinguished from all other ricefishes by males with first six rays of the anal fin elaborate and elongate, separated from rest of the fin as an intromittent organ, used to transfer spermatophores (barbed, encapsulated sperm bundles) to females, who lay fertilized eggs; second to sixth analfin rays of females elongate and thickened; females bilaterally asymmetric with only the left pelvic bone and pelvic-fin rays and urogenital opening left of the ventral midline in most specimens; testes single (as opposed to paired), bulbous; maxilla absent. Head length the smallest of all ricefishes, ranging from 14 to 19% SL, as opposed to 20% or more in all other ricefishes. Dorsal-fin origin the most posterior among ricefishes; the dorsal-fin lies above vertebra 27 as opposed to above or anterior to vertebra 24. Teeth are enlarged posteriorly on the premaxilla in both sexes, as in O. javanicus and O. carnaticus , not considered as close relatives. Oryzias setnai shares with three other miniatures, O. pectoralis , O. uwai and O. minutillus , a pigmented anal or urogenital region and an elongate, rounded caudal fin. Oryzias setnai is hypothesized to be most closely related to O. uwai and O. minutillus with which it shares i,3/4,i rather than i,4/5,i principal caudal-fin rays, a medial extension of the ethmoid cartilage, and anterior anal-fin rays elongate and set off from the rest of the fin. Oryzias setnai and O. uwai share an interrupted, horizontal dark brown bar that runs from the eye to the lower jaw; a mesethmoid that is uniquely subrectangular, rather than round or oval; and a first epibranchial that is cartilaginous, not ossified.

Description: Miniature, maximum size of specimens examined 22.5 mm SL. Body elongate, slender, compressed laterally, body depth 14–20. No pronounced abdominal concavity between pelvic fins and anal fin. Mouth subterminal, lower jaw projecting slightly beyond upper jaw. Dorsal body profile relatively straight from head to dorsal-fin origin; ventral body profile relatively straight from head to anal-fin origin. Dorsal surface of head slightly convex just anterior to orbits. Head length 14–19; snout length 3–4; eye moderate, 7–8, orbits meet dorsal surface of head. Basal portion of dorsal and anal fin do not project significantly beyond primary body profile. Scales relatively large, cycloid; 32–34 in a lateral series. Anal-fin rays of males without bony contact organs; first six anal-fin rays elaborate and elongate, separated from rest of the fin as an intromittent organ used to transfer spermatophores (encapsulated sperm bundles) to females ( Kulkarni, 1940). Females bilaterally asymmetric in having only left pelvic bone and pelvic-fin rays, and urogenital opening left of ventral midline in most specimens. Medialmost pelvic-fin ray connected to body via a membrane along its proximal portion. Caudal fin with elongate middle rays.

Premaxilla short and broad with distinct ascending process; premaxilla and dentary with a single, irregular row of caniniform teeth; males and females with two or three enlarged posterior teeth on the premaxilla, no enlarged teeth on the dentary; tooth tips project through lips. Maxilla absent. No preethmoid cartilage; ossified portions of mesethmoid subrectangular; ethmoid cartilage rectangular with anterior projection. 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 second 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 in line with third pleural rib in females, fourth pleural rib in males. Caudal skeleton with two epural bones; two ventral accessory cartilages. Fifth ceratobranchial toothplates triangular, with teeth in irregular rows anteriorly, followed by 2–3 rows of unicuspid teeth. Basihyal bone relatively short and triangular, basihyal cartilage extremely elongate and rectangular. Epibranchial 1 cartilaginous; epibranchial 2 notably smaller than the other epibranchial elements.

Dorsal-fin rays 6–7. Anal-fin rays 27–32. Pelvic-fin rays 5. Pectoral-fin rays 10. Principal caudal-fin rays i,3–4/4,i. Procurrent fin-rays, dorsal 2–3, ventral 3–4. Vertebrae 31–34 (8–10 + 21–25). Branchiostegal rays 4.

Cytogenetic data: Unknown.

Colour in life: Nearly transparent, hence one common name, Indian glaskilli; discrete blackish spot just posterior to orbit; scattered minute melanophores on dorsal and anal fin interradial membranes, body, and upper jaw.

Colour in alcohol: A diffuse 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. An interrupted, horizontal dark brown bar from the eye to the tip of the lower jaw in some specimens. A faint black line along the anal-fin base. Urogenital region with dense brown to black spot(s). Dorsal and anal fin interradial membranes, body and upper jaw, with scattered, minute melanophores.

Distribution and habitat: Fresh and brackish water habitats along the west coast of India from near the Gulf of Kutch to Trivandrum (Kerala) near the southern extent of the Indian subcontinent ( Silas, 1959; Talwar & Jhingran, 1991).

Remarks: A detailed osteological and soft anatomical study was included as part of Kulkarni’s (1940) original description of Horaichthys setnai . Data were augmented by those in Kulkarni (1940).

Böhlke (1953: 54) refers to the CAS-SU type material by stating: ‘These specimens are called syntypes because of Kulkarni’s statement in the original description: “Type-specimens.- No. F13203/1, Zoological Survey of India (Indian Museum), Calcutta.” ’ The lot, CAS-SU 35960, was collected from brackish water near Bombay, India, by C. V. Kulkarni in 1938. Here, I also recognize USNM 118687 (4) and UMMZ 131839 (4) as part of the syntype series. These eight specimens were collected from Bombay by Kulkarni in 1938. Half of these specimens were sent later that year by S. L. Hora of the Zoological Survey of India to George S. Myers, then of Stanford University, and half to Carl L. Hubbs, then of the University of Michigan. Myers subsequently donated his four specimens to the USNM where they were accessioned on 1.iv.1941. A hand-written note, part of the accession records, dated 22.iv.1941, from Myers to Leonard P. Schultz, then of the USNM, states: ‘As to the Horaichthys, I sent you all 4 of the first specimens Hora sent to me (as detailed in Kulkarni’s paper) since Hora later sent me more material. The four you have are the ones on which I based my opinion of the fish, as sent to Hora and Kulkarni.’ Specimens of the new fish were sent to Myers and to C. L. Hubbs, then at the University of Michigan, prior to its description, ‘... to obtain views of other ichthyologists interested in this group of fishes’ ( Kulkarni, 1940: 380). I likewise view the specimens in USNM 118687 and UMMZ 131839 as syntypes because they were on hand as Kulkarni prepared the description of his new species. An additional 87 syntypes are catalogued as ZSI F13202/1-13204/1 ( Menon & Yazdani, 1968). An additional lot, USNM 197764, also collected by Kulkarni, no date recorded, is not considered part of the syntype series because it has a much later date of accession (12.ii.1964) and cannot be confirmed as part of the material Kulkarni had at hand when he was preparing his description. I do not designate a lectotype from among the syntypes because I am uncertain if the above syntypes comprise the entire type series.

Other common names for this species include thready killifish or thready top-minnow ( Talwar & Jhingran, 1991: 746), Malabar ricefish ( Robins et al., 1991) and Indian Glaskilli ( Seegers, 1997: 18).

Material examined: 335 specimens (7.5–22.5 mm SL). Syntypes. INDIA. Brackish water near Bombay: CAS-SU 35960 , 17 (10 males, 17.9–19 mm, 8 females, 19–21.3 mm), USNM 118687 , 4 (2 males, 2 females, 17.5–20 mm), UMMZ 131839 , 4 (18–20 mm), C. V. Kulkarni, 1938 .

Non-type specimens. INDIA. Karnataka State: Shambavi R., 30 km N of Mangalore, about 1–2 km inland, CAS 56255, 53 (19 males, 29 females, 5 juv. or sex undet., 11.0– 18 mm, 4 of which, 2 males and 2 females, have been cleared and counterstained), USNM 277482 , 106 (7.5–22.5 mm, 4 of which have been cleared and stained with alcian blue, 2 of which have been counterstained, 2 of which have been cleared and stained with alizarin), BMNH 1985.9.11: 1–45, 27 (10.5–17.5 mm), ANSP 157315 , 34 (10.0– 17.0 mm, 4 of which have been cleared and stained solely with alizarin), T. R. Roberts, i.1985; Bombay Prov., Uttan in Thana dist., USNM 197764 , 6 (2 males, 4 females, 16.5–18.3 mm); AMNH 36576 , 84 (10–18.1 mm, 10 of which have been cleared and counterstained), C. V. Kulkarni, no date recorded .

Figures

Figure 16. A, Oryzias uwai, CAS 92309, paratype, female, 13.0 mm SL; B, Oryzias setnai, USNM 277482, female, 17.5 mm SL. Arrows point to interrupted, horizontal dark brown bar from the eye to the tip of the lower jaw in O. uwai, and to the posterior extent of the lower jaw in O. setnai.

Figure 20. A, Oryzias setnai, USNM 277482, 14.5 mm SL; B, O. uwai, CAS 92310, 12 mm SL; C, O. minutillus, CAS 58022, 11 mm SL. Anterior portion of skull and jaw and jaw suspensorium. Arrow points to the medial anterior extension of the ethmoid cartilage. Scale bar = 0.5 mm.

Figure 26. A, Oryzias setnai, CAS 56255, male, 18 mm SL, SEMX134. B, Oryzias javanicus, CAS 58026, adult male, 26 mm SL, SEMX53. C, Oryzias celebensis, CAS 58034, adult female, 29 mm SL, SEMX40, teeth on right half of toothplate dislodged during specimen preparation. D, Oryzias bonneorum, ZMA 123.863, female, 40 mm SL, SEMX23. SEM of a right fifth ceratobranchial bone and toothplate. Anterior is up.

Figure 27. A, Melanotaenia splendida, USNM 308410, 24 mm SL; scale bar = 1 mm. B, Oryzias setnai, USNM 277482, 17 mm SL; scale bar = 0.5 mm. Dorsal portion of skull and anterior vertebrae. V1 = first vertebra. Anterior is up.

Figure 55. Oryzias setnai (Kulkarni, 1940), Bombay, India, USNM 197764, male, 18.5 mm SL, above; female, 16.5 mm SL, below. Left pectoral fin in female specimen is folded anteriorly.