Kamoharaia megastoma ( Kamohara, 1936 )

Lisher, Mark W., Gon, Ofer, Heemstra, Elaine & Viana, Sarah T. F. L., 2020, First record of the rare Wide-mouth flounder Kamoharaia megastoma (Kamohara, 1936) (Pleuronectiformes, Bothidae) from the western Indian Ocean collected during the ATIMO VATAE expedition to Madagascar “ Deep South ”, Zoosystema 42 (11), pp. 151-157 : 155-156

Kamoharaia megastoma ( Kamohara, 1936)

( Figs 1-4 ; Table 1 )

Chascanopsetta megastoma Kamohara, 1936: 306 .

Kamoharaia megastoma – Kuronuma 1940: 35.

TYPE LOCALITY. — Mimase, Kochi Prefecture, Japan.

COMMON NAMES. — Wide-mouthed flounder, Wani-garei (Japanese), keun-ip-dung-geul-neop-chi-sok (Korean).

MATERIAL EXAMINED. — Madagascar • 1 specimen; MNHN- IC-2019-0265 (formerly SAIAB 189569); 102.37mm SL; Sud Pointe Barrow , Madagascar, southwestern Indian Ocean; 25°33’S, 44°18’E; 155 -156 m depth; 10.V.2010; B. de Forges, S. Rafamatanantsoa and E. Ranaivoson leg.; ATIMO VATAE; FV Nosy Bé 11 • 1 specimen; SAIAB 189569 ; 99.65 mm; same data as preceding • 1 specimen; SAIAB 189603 ; 108.72 mm SL; Sud-Ouest Pointe Barrow , Madagascar, southwestern Indian Ocean; 25°02’S, 43°59’E; 300-309 m depth; 11.V.2010; B. de Forges, S. Rafamatanantsoa and E. Ranaivoson leg.; ATIMO VATAE; FV Nosy Bé 11 • 1 specimen; SAIAB 189783 ; 131.16 mm SL; Sud Pointe Barrow , Madagascar, southwestern Indian Ocean; 25°33’S, 44°16’E; 549-576m depth; 10.V.2010; B. de Forges, S. Rafamatanantsoa and E. Ranaivoson leg.; ATIMO VATAE; FV Nosy Bé 11.

DESCRIPTION

Body oblong, somewhat elongate, greatest depth 35.4-38.7% SL. Head relatively short, 18.9-19.9% SL. Mouth extremely large; jaws elongate; maxilla extending beyond dorsal contour of snout; tip of vomer protruding well into mouth cavity ( Fig. 3 ). Teeth arranged in a single series; three pairs of enlarged teeth on anterior tip of lower jaw, greater than twice the length of adjacent teeth in lower jaw; all teeth in lower jaw curved backwards. Teeth in upper jaw significantly shorter than those in lower jaw and more numerous, villiform tooth-band on posterior half; three to four pairs of enlarge teeth on anterior tip of upper jaw, greater than twice the length of adjacent teeth in upper jaw; all teeth in upper jaw conical ( Fig. 3C ). Eyes of moderate size, upper eye slightly larger than lower eye (25.2-33.4% HL vs 23.2-30.7% HL); situated at the same level and close together with a short interorbital width of 3.6-5.0% HL. Lateral line on ocular side running from uppermost opercular opening to caudal peduncle, with small curve above base of pectoral fin; 114-131 pored lateral line scales. Lateral line absent on blind side. Dorsal fin originating above snout, with 108-109 rays (all unbranched). Origin of anal fin slightly posterior to anus with 83-85 rays (all unbranched). Pectoral fin on ocular side substantially longer than on blind side (116.8-130.0% HL vs 36.4-45.9% HL); 10-12 rays on both ocular and blind sides. Pelvic fins short on both ocular and blind sides, origin of blind side at level of 3rd ray of ocular side; 6 rays on both ocular and blind sides. Caudal fin of moderate length (13.6-16.3% SL), its posterior margin somewhat rounded. Body scales on both ocular and blind sides cycloid; circular shape, uniform throughout both ocular and blind sides. Lateral line scales oval to rounded shape; circuli distinct on anterior and lateral fields; radii present in anterior field; tubular wide (32.98% scale width) and extending 69.95% of the scale length ( Fig. 4 ).

Fresh colouration

Ocular side of body greyish throughout with darker grey blotches. Blind side of body whitish. Dorsal and anal fins greyish with distal half darker grey to blackish. Ocular side pectoral fin black; blind side pectoral fin translucent. Pelvic fins whitish. Caudal fin greyish with central rays darker grey to blackish ( Fig. 2A ).

Preserved colouration

Ocular side of body light brown throughout, with dark blotches scattered throughout body; blind side light brown throughout. Ocular side pectoral fin black; blind side pectoral fin translucent. Pelvic fins whitish. Dorsal and anal fins light brown with distal half greyish. Caudal fin light brown with central rays greyish, and posterior third greyish ( Fig. 2B, C ).

Figures

FIG. 1. — Map of geographical distribution of Kamoharaia megastoma (Kamohara, 1936) in the Western Pacific and southeastern Indian Ocean (red,after Hensley & Amaoka (2001)) and the southwestern Indian Ocean off Madagascar (yellow stars).

FIG. 2. — Kamoharaia megastoma (Kamohara, 1936), SAIAB 189603, 108.7 mm SL, Sud-Ouest Pointe Barrow, Madagascar: A, ocular side fresh specimen (photograph by S. Ribes); B, ocular side preserved specimen; C, blind side preserved specimen. Scale bar: 20 mm.

FIG. 3. — Kamoharaia megastoma (Kamohara,1936),SAIAB 189603,108.7 mm SL, Madagascar: A, close-up of ocular side of head; B, close-up of blind side of head; C, close-up of ocular side of mouth. Scale bars: A, B, 20 mm; C, not to scale.

FIG. 4. — Kamoharaia megastoma (Kamohara,1936), SAIAB 189603,108.7 mm SL, Madagascar: A, lateral line scale ocular side; B, body scale ocular side; C, body scale blind side. Scale bars: 200 µm.