Eviota nigrispina, Greenfield, David W. & Suzuki, Toshiyuki, 2010

Greenfield, David W. & Suzuki, Toshiyuki, 2010, Eviota nigrispina, a New Goby from the Ryukyu Islands, Japan (Teleostei: Gobiidae), Zootaxa 2655, pp. 57-62 : 57-61

Eviota nigrispina n. sp.

Blackspine Pygmygoby Japanese name—Nadeshiko-isohaze ( Figs.1–5 )

Eviota pellucida (non Larson). Hayasi & Shiratori, 2003: 57, figs. 105–106. Eviota sp. 2. Senou et al., 2004: 142 (underwater photograph, Iriomote-jima Island, the Ryukyu Islands, Japan, 6 m depth).

Holotype: OMNH-P35615, 14.1 mm SL male, Japan, Ryukyu Islands, Nagura Inlet, Ishigaki-jima Island, (24°24’01.50”N, 124°06’39.81”E), 20 m, field number S-18161, from aquarium fish supplier in Ishigaki Island, 3 March 2010.

Paratypes: CAS 229934, 15.0 mm SL male, Japan, Ryukyu Islands, Nagura Inlet, Ishigaki-jima Island, (24°20’12.57”N, 123°42’49.27”E), from aquarium fish supplier in Ishigaki Island, ex-OMNH-P32482; OMNH-P35614, 12.3 mm SL female, Japan, Ryukyu Islands, Nagura inlet, Ishigaki-jima Island, (same location as holotype), 20 m, field number S-18160, from aquarium fish supplier in Ishigaki Island, 3 March 2010; OMNH-P35640, 9.7 mm female, Japan, Ryukyu Islands, Funauki, Iriomote-jima Island, (24°20’18.42”N, 123°42’52.52”E), field number S-3918, T. Suzuki & M. Suzuki, 23 August 1994; OMNH- P35254, 8.5 mm SL immature, Japan, Ryukyu Islands, Funauki, Iriomote-jima Island, (24°20’12.57”N, 123°42’49.26”E), field number S-17908, T. Suzuki, M. Suzuki, & A. Kawai, 6 July 2009.

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; 5th 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.

Description. Dorsal-fin rays VI+I,8; anal-fin rays I,7; pectoral-fin rays 16 (15–16), rays not branched; 5th segmented pelvic-fin ray 6% of 4th ray or less; branches on 4th 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 freshly collected male holotype, OMNH-P35615: ( Fig. 1 ) Body semitranslucent with an internal black stripe centrally along the backbone, extending from opercle posteriorly to caudal-fin base, widest at opercle and tapering posteriorly. Scales on dorsum above black stripe with orange pigment along scale pockets. Scales ventral to those on dorsum with strong black pigment on scale pockets. Ventral half of body silver along abdomen and with seven black internal bars extending from backbone down to ventral midline between anal-fin origin and caudal-fin base. Head red overlaid with many small, black dots as an extension of the black stripe. Nape abruptly orange above red of head and black stripe. Ventral side of head red-orange extending posteriorly to pelvic-fin origin. Genital papilla orange. Pupil of eye surrounded by yellow-gold iris edged in black. First dorsal fin with many small, black dots along basal half. Second dorsal, anal, and caudal fins peppered with many small, black dots. Pelvic-fin rays dusky, membranes clear.

Color of freshly collected female paratype, OMNH-P35614: ( Fig. 2 ) Body semitranslucent with an internal black stripe centrally along and below the backbone, extending from behind the eye to caudal-fin base. Seven internal black bars extending from backbone down to ventral midline between anal-fin origin and caudal-fin base, with yellow-gold areas between the five posterior black spots. A few short, red triangles extending dorsally from black stripe opposite the black caudal-peduncle spots. Area under first dorsal fin clear, with scale pockets outlined in red. Nape yellow-gold with some red areas. Snout and ventral surface of head red-orange. Ventral surface of head from preopercle back to anal-fin origin silver-white. Pelvic-fin rays dusky, membranes clear. First dorsal fin with reddish spines and many small, black dots along basal half. Second dorsal, anal and caudal fins peppered with many small, black dots, the rays reddish. Eye black.

Color of freshly collected immature paratype, OMNH-P35254: ( Fig. 3 ) Body translucent from back of head to caudal-fin base. A narrow red stripe above backbone and a broader black stripe below backbone. A series of yellow blotches on upper half of body between backbone and second dorsal-fin base. A few yellow blotches between black stripe and ventral midline on caudal peduncle. A curved orange line above abdomen through the black stripe. Head and nape orange with scattered red and black dots. Ventral surface of head white as is belly and pelvic fins. All other fins with orange membranes. Pupil of eye surrounded by yellowgold iris edged in black.

Color in life: ( Fig. 4 ) Body translucent and clear with an internal black stripe centrally along the backbone, extending from the eye posteriorly to the caudal-fin base. The black stripe is widest from the head to the end of the abdomen and then abruptly narrows and tapers to the caudal-fin base. The black stripe with a narrow, bright yellow-gold line that curves down from the dorsal part of the eye to the posterior end of the abdomen. The ventral portion of the black stripe lined with silver along the abdomen and the dorsal portion with a very narrow yellow-gold line that extends from between the eyes to the end of the abdomen. Scale pockets with redish edges dorsally and black edges ventrally. Snout and area behind eye onto cheek red. Lower part of head translucent. Pupil of eye surrounded by a yellow-gold iris with red areas and black on dorsal edge. Peppering of small, black dots on dorsal, anal, and caudal-fin membranes.

Color of holotype in preservative: ( Fig. 5 ) Body white with strong black pigment on scale pockets on ventral half of sides of body. Scales on dorsal half white as is the nape. Head overlaid with many small, black dots. A short internal black line at midline of caudal-fin base. Pupil of eye surrounded by white iris, ringed in black. Basal half of first dorsal fin peppered with small, black dots. Second dorsal, anal, and caudal fins peppered with small, black dots.

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

Etymology. The specific epithet is an adjective combining the Latin nigra (black) and spina (backbone), referring to the black pigment extending along the backbone.

Comparisons. Eviota nigrispina belongs to the cephalic sensory-pore pattern 2 of Lachner and Karnella (1980), lacking only the IT pore. Eviota nigrispina differs from all other species of Eviota by its distinctive color pattern. It differs from species in pattern group 2 as listed in Gill and Jewett (2004) and Greenfield and Randall (2008), as follows. Only seven described species in pattern group 2 have simple unbranched pectoralfin rays as in E. nigrispina : E. cometa Jewett and Lachner (1983) , E. pellucida Larson (1976) , E. prasites Jordan and Seale (1906), E. sigillata Jewett and Lachner (1983) , E. spilota Lachner and Karnella (1980) , E. storthynx Rofen (1959) , and E. zebrina Lachner and Karnella (1978) . Of these, only E. prasites , E. pellucida , and E. storthynx always have a dorsal/anal formula of 8/7 as in E. nigrispina . Eviota nigrispina differs from both E. prasites and E. pellucida by having the 5th pelvic-fin ray about 6% or less of the 4th ray, versus about 40%. Eviota nigrispina shares the most characters with E. storthynx , but E. storthynx has a dark postocular spot and vertical bars or dark reticulated markings on the caudal fin that are both lacking in E. nigrispina .

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.

Figures

FIGURE 1. Eviota nigrispina, male, holotype, OMNH-P 35615, freshly collected. Photograph by T. Suzuki.

FIGURE 2. Eviota nigrispina, female, paratype, OMNH-P 35614, freshly collected. Photograph by T. Suzuki.

FIGURE 3. Eviota nigrispina, immature, paratype, OMNH-P 35254, freshly collected. Photograph by T. Suzuki.

FIGURE 4. Eviota nigrispina, color in life. Kasari-wan Inlet, Amami-oshima Island, the Ryukyu Islands, Japan, 7 m depth. Photograph by H. Kanehara.

FIGURE 5. Eviota nigrispina, male, holotype, OMNH-P 35615, preserved.