Blackspine Dwarfgoby

description

Description. Dorsal-fin rays VI + I, 8; anal-fin rays I, 7; pectoral-fin rays 16 (15 – 16), rays not branched; 5 th segmented pelvic-fin ray 6 % of 4 th ray or less; branches on 4 th pelvic-fin ray 5 (4 – 6), 3 segments between branches; 11 (11 – 12) branched caudal-fin rays; segmented caudal-fin rays 17; lateral scale rows 24; transverse scale rows 7; breast and pectoral-fin base scaleless; anterior spines of first dorsal fin extending past origin of second dorsal fin; pelvic fins reaching to or past anal-fin origin; cephalic sensory-pore system pattern 2 (only IT missing); male genital papilla non-fimbriate. Measurements (based on holotype and three paratypes): Standard length 9.7 – 15.0 mm; head length 31.8 (30.3 – 32.8, 31.8); origin of first dorsal fin 32.9 (32.9 – 38.9, 36.4); origin of second dorsal fin 56.5 (54.7 – 60.7, 57.7); origin of anal fin 63.6 (57.7 – 63.6, 61.3); caudal-peduncle length 24.7 (24.7 – 27.9, 26.4); caudalpeduncle depth 13.4 (12.9 – 13.4, 13.1); body depth 21.2 (19.8 – 23.1, 21.6); eye diameter 10.6 (9.7 – 12.3, 11.1); snout length 4.6 (3.6 – 4.9, 4.4); pectoral-fin length 30.4 (20.0 – 35.9, 30.2); pelvic-fin length 33.2 (33.2 – 42.0, 36.9). Color of fr

Eviota nigrispina, a New Goby from the Ryukyu Islands, Japan (Teleostei: Gobiidae)

diagnosis

Diagnosis. The following combination of characters distinguishes E. nigrispina from congeners: cephalic sensory-pore system pattern 2 (only IT pore missing); dorsal-anal fin ray formula 8 / 7; pectoral-fin rays unbranched; anterior spines of first dorsal fin filamentous; genital papilla non-fimbriate; 5 th pelvic-fin ray short, about 6 % or less; an internal black stripe along the backbone area from head to caudal-fin base in live or freshly caught fish, and strong black pigment along scale pockets on the ventral half of the sides when preserved.

Eviota nigrispina, a New Goby from the Ryukyu Islands, Japan (Teleostei: Gobiidae)

discussion

Remarks. Recognizing species of Eviota underwater has been difficult for many years. Early workers did not have information on live or fresh color, and when specimens are preserved most color is lost except for some dark markings. Because of this those working with preserved material could not readily identify underwater photographs of live individuals. As discussed by Greenfield and Randall (2010), species that look quite different when alive were not recognized as separate when preserved. Added to this is the problem of changes in coloration upon death as demonstrated here for E. nigrispina. The distinctive, yellow-gold line that curves across the black stripe over the abdomen in living E. nigrispina was only faintly visible in an immature fresh individual (Fig. 3), but not in mature males or females.

Eviota nigrispina, a New Goby from the Ryukyu Islands, Japan (Teleostei: Gobiidae)

distribution

Distribution. Amami-oshima Island, Kakeroma Islands, Ishigaki-jima Island and Iriomote-jima Island, the Ryukyu Islands, Japan.

Eviota nigrispina, a New Goby from the Ryukyu Islands, Japan (Teleostei: Gobiidae)