Oryzias hubbsi, ROBERTS, 1998

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 : 564-565

ORYZIAS HUBBSI ROBERTS, 1998

HUBBS’ S MEDAKA

FIGURES 13B , 42

Oryzias javanicus .- Uwa & Iwata, 1981: 24–26 [karyotype and cellular DNA content of wild-caught specimens subsequently used as type series of O. hubbsi Roberts, 1998 ].- Uwa, 1986: 867–875 [cytogenetic comparisons].

Oryzias hubbsi Roberts, 1998: 222 , fig. 2g [type locality: Indonesia: Java: Jakarta and near Bandung].- Parenti, 2000a: 2150 [listed].

Differential diagnosis: Oryzias hubbsi is a miniature (largest specimen known 21.3 mm) ricefish species in a group including O. carnaticus , O. dancena , O. haugiangensis and O. javanicus that share closed rather than open lacrimal sensory canals. Oryzias hubbsi shares with another miniature, Oryzias haugiangensis , a large head (31% or more of SL), large eye diameter (reaching 10% or more of SL), and an anterior dorsal fin (its origin anterior to vertebra 22). They differ in that the lateral strut of the pelvic bone is blunt (rather than elongate and needle-like) in O. hubbsi . Oryzias hubbsi further differs from O. haugiangensis in having a rounded, rather than truncate, caudal fin; extremely enlarged urogenital papilla in females (the largest in ricefishes); and eight to nine (as opposed to 10–11) pectoral-fin rays.

Description: Miniature, maximum size of specimens examined 21.3 mm SL. Body compressed laterally, slender, body depth 19–24 [19]. No pronounced abdominal concavity between pelvic fins and anal fin. Mouth terminal, lower jaw projecting slightly beyond upper jaw. Dorsal body profile relatively straight from head to dorsal-fin origin; ventral body profile slightly convex or rounded from head to anal-fin origin. Dorsal surface of head slightly convex just anterior to orbits. Head length 25–32 [29]; snout length 8–9 [9]; eye large, 9–10 [9], orbits meet dorsal surface of head. Basal portion of dorsal fin projects slightly beyond primary body profile. Scales relatively large, cycloid; 28–29 in a lateral series (scale count approximate). Dorsal and anal fin slightly rounded, no elongate fin rays; anal-fin rays with extremely small bony contact organs. Medialmost pelvic-fin ray connected to body via a membrane along its proximal half. Caudal fin rounded, elongate. Male with short tubular urogenital papilla; female with extremely large, bilobed urogenital papilla.

Premaxilla short and broad with no distinct ascending process; premaxilla and dentary with a single irregular row of caniniform teeth; enlarged unicuspid premaxillary and dentary tooth in males. No preethmoid cartilage; ossified portions of mesethmoid discshaped; anterior border of ethmoid cartilage straight. 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 in line with third pleural rib. Caudal skeleton with two epural bones; one ventral accessory bone and one accessory cartilage. Fifth ceratobranchial toothplate triangular, with teeth in four discrete rows of unicuspid teeth, the most anterior row with just two teeth, and no incomplete posterior row. Basihyal bone triangular, basihyal cartilage elongate and rectangular. Epibranchial elements fully ossified; epibranchial 2 notably smaller than the other epibranchial elements.

Dorsal-fin rays 5–6. Anal-fin rays 16–19. Pelvic-fin rays 6. Pectoral-fin rays 8–9. Principal caudal-fin rays i,4/5,i. Procurrent fin-rays, dorsal 5, ventral 5. Vertebrae 27–28 (9–10 + 17–19). Branchiostegal rays 4–5.

Cytogenetic data: Laboratory stocks of O. hubbsi , then identified as O. javanicus , were reported to have 2 n = 48, with 23 pairs of acrocentric chromosomes, one pair of subtelocentric chromosomes and an arm number (NF) of 48 ( Uwa & Iwata, 1981; Table 2).

Colour in life: Unknown.

Colour in alcohol: Ground colour pale straw. 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. A faint black line along the anal-fin base. Dorsal- and anal-fin interradial membranes with scattered melanophores. Body covered with minute melanophores in some specimens.

Distribution and habitat: Endemic to western Java, Indonesia, from streams in Jakarta and the low, hilly areas at elevations from about 700 to 1000 m in the vicinity of Bandung.

Material examined: 123 specimens (10.6–21.3 mm SL). Holotype. INDONESIA. Java: Jakarta, CAS 58029, female, 17.5 mm, laboratory stock from wild-caught fish, K. Hirata & T. Iwamatsu, 1.v.1983.

Paratypes. INDONESIA. Java: CAS 92322, 6 (14.4– 16.6 mm, 1 of which, 15.5 mm, has been cleared and counterstained) taken with the holotype; UMMZ 146573 , 58 (10.6–21.3 mm, 8 of which, 14.3–19.6 mm, have been cleared and stained for bone), Situ Tjiburuj, near Padalarang , 20 km W of Bandung, elev. c. 700 m, C. L. Hubbs, 22.v.1929 ; UMMZ 146571 , 30 (10.9–17.9 mm), Lake Bagendit, near Garut , elev. c. 700 m, C. L. Hubbs & V. Arragon, 26.v.1929 ; UMMZ 198991 , 12 (13.5–18.9 mm), environs of Jakarta,. i.1940 , Director of Batavia (= Jakarta) Museum; UMMZ 146572 , 4 (13.9–18.1 mm), Tjiti = is (creek) just below road near mouth in Tjimanoek , 3 km N of Gatur, elev. nearly 700 m, C. L. Hubbs, V. Arragon, et al., 26.v.1929 ; UMMZ 146557 , 2 (15.1–15.5), pond in Botanical Gardens, Buitenzorg (= Bogor ), A. Thienemann, 29.ix.1928 ; UMMZ 146574 , 4 (13.6– 18.2 mm), trib. and ricefields to Tjikunir, Tjiwaelen system (or E fork), 2 km N of Kampong Tjikunir, 7 km W of Tasikmalaja , C. L. Hubbs, 28.v.1929 ; UMMZ 146567 , 2 (12.7–17.0 mm), Outer Harbor Canal and connected waters about aquarium, Pase Ikan district, Batavia (= Jakarta), coll. C. L. Hubbs, 8.v.1929 .

Non-type specimens. INDONESIA. Java: CAS 92327 (ex. CAS 58029), 2 specimens cleared and counterstained; Buitenzorg (= Bogor) , USNM 72563 , 2 (15.5–17.2mm), Bryant & Palmer, 3.iv.1909 .

Figures

Figure 13. A, Oryzias haugiangensis, CAS 93898, female, 16 mm SL. B, O. hubbsi, CAS 92322, female, 16 mm SL. Lateral view of body to show large bilobed urogenital papilla just posterior to pelvic fins of adult females. Extremely large urogenital papilla is an autapomorphy of the miniature O. hubbsi.

Figure 42. Oryzias hubbsi Roberts, 1998, laboratory stock of fish collected in Jakarta, Java, Indonesia, CAS 92322, paratype, male, 14.5 mm SL.