Hypseleotris cyprinoides

Thacker, Christine & Unmack, Peter J., 2005, Phylogeny and Biogeography of the Eleotrid Genus Hypseleotris (Teleostei: Gobioidei: Eleotridae), With Redescription of H. cyprinoides, Records of the Australian Museum 57 (1), pp. 1-13 : 10

Redescription of Hypseleotris cyprinoides

Hypseleotris cyprinoides (Valenciennes in Cuvier & Valenciennes, 1837: 248).

Synonyms. Hypseleotris bipartita Herre, 1927 ; H. dayi Smith, 1950 ; H. guentheri ( Bleeker, 1875) ; H. leuciscus ( Bleeker, 1853) ; H. tohizonae ( Steindachner, 1880) ; Asterropteryx modestus Bleeker, 1875 .

Type material SYNTYPES: 2, MNHN A–1568; 1, MNHN 2099 .

Type locality. Saint Maurice River, Reunion Island.

Material examined. See list under “Specimens examined” above.

Differential diagnosis. Hypseleotris cyprinoides is distinguished from all other Hypseleotris by the presence of scales extending anteriad to the interorbital region.

Description

Dorsal VI+I,8–9; anal I,9–11; vertebrae 14+10; dorsal pterygiophore formula 3–1221 or 3–12210. 24–27 scales in longitudinal series. Body laterally compressed, depth 3.9 to 4.6 in length. Eye diameter 3.7 to 4.6 in head, interorbital 1.0 to 1.2 times eye diameter. Head depressed, with small terminal mouth just reaching anterior margin of orbit. Caudal fin rounded.

Body covered with large scales, those on head and predorsal and preventral regions cycloid, the remainder ctenoid, small ctenoid scales on base of caudal, scales on top of head extend forward to between nostrils, operculum scaled, cheek scaled to beneath orbit. Colour in alcohol brown, countershaded darker on dorsal half, melanophores concentrated on posterior scale margins, sometimes coalesced into a dark midlateral stripe that may extend anteriad onto operculum and snout. Distinct dark blotch on dorsal half of pectoral-fin base and lower half of caudal-fin base. Median fins mottled except second dorsal fin in males; second dorsal fin in males with pale spots on dark ground on proximal third to half, alternating dark and pale stripes on distal two thirds to half. This species is amply illustrated; examples include Allen (1991), Bruton (1996), Hoese (1986), and Kottelat et al. (1993).

Remarks

Hypseleotris cyprinoides is redescribed in order to clarify the identity of this widespread species, and to include the various taxa here synonymized with it. The nominal species H. bipartita , H. dayi , H. tohizonae , H. leuciscus , H. modestus , and H. guentheri all agree in meristic values and overall proportions, and have been distinguished on the basis of colouration. The colouration is somewhat variable, but there is always an obvious black spot present on the ventral half of the caudal peduncle at the edge of the caudal fin (in addition to the Hypseleotris -diagnostic blotch at the upper base of the pectoral fin). The remainder of the body may be faintly speckled with black (as described in the original description of Eleotris [ Hypseleotris ] cyprinoides Cuvier & Valenciennes 1837 [excerpted in Herre, 1927], and in accounts of H. dayi [ Hoese, 1986]), or without any dark pigment. Descriptions of H. tohizonae ( Steindachner, 1880) , H. leuciscus ( Kottelat et al., 1993) , and H. guentheri ( Günther, 1861; Bleeker, 1875; Ogilby, 1898; Allen, 1991) differ only in that the fine black spots are concentrated on the posterior margins of the scales, and aggregated into a lateral black band that extends to and meets the black spot on the caudal peduncle. In smaller individuals (up to approximately 35 mm SL) the body is more slender, without the lateral stripe and with clear or faintly brown-spotted median fins. Larger individuals feature the lateral stripe, a stockier body and median fins with more pronounced colouration: two pale stripes on black ground in the first dorsal fin, and three to four rows of pale spots on black ground on the proximal portion of the second dorsal fin. This degree of variation is also found in the other widespread Hypseleotris species, H. compressa , which exhibits variation in colour patterns and morphology that slowly changes with age, and may change rapidly depending upon mood or reproductive state (Larson & Hoese, 1996).