Eviota atriventris, Greenfield & Suzuki, 2012

Greenfield, David W. & Suzuki, Toshiyuki, 2012, Eviota atriventris, a New Goby Previously Misidentified as Eviota pellucida Larson (Teleostei: Gobiidae), Zootaxa 3197 (1), pp. 55-62 : 56-61

Eviota atriventris n. sp.

Blackbelly Dwarfgoby (English name), Shiroobi isohase (Japanese name) ( Figs. 1 , 6–8 )

Eviota pellucida (non Larson). Randall, 1997:6, fig. 7; Myers 1999: 254, Pl. 160B; Laboute & Grandperrin, 2000: 409, fig.; Ikeda et al., 2003: 57, figs. 105–106; Senou, et al., 2004: 137, fig.; Randall, 2005: 533, fig.

Holotype: ROM 76339, 17.1 mm male, Palau, due west of Koror where lagoon rises to outer barrier reef, 07º20’44.3” N, 134º16’47.2” E, 0–7.9 m, patch reef of numerous Porites bommies, rotenone, field number RW04- 12, R. Winterbottom, W. Holleman, B. Hubley, and D. Winterbottom, 24 May 2004.

Paratypes: ROM 88226, 7 males 9.2–13.9 mm, 7 females 11.4–16.7 mm, taken with holotype ; ROM 84482, 17.8 mm male, Palau, Sonsoral Island , southwest islands, east coast Sonsoral 2/3rds way south from north tip, 05º19’18” N, 132º E, 20–36 m, corals and various algae, rotenone, field number RW08-02 , R. Winterbottom , M. Westneat, J.Williams, W. Holleman, B. Hubley, M. Winterbottom, and C. McCord, 11 September 2008 . ROM 84498, 17.3 mm female, Palau, off southeast tip of Pulo Anna , about 10 m from surf line, 04º39’09” N, 131º57’16” E, 7–15 m, channel, various corals, rotenone, field number RW08-09 , R. Winterbottom , M. Westneat, J.Williams, W. Holleman, B. Hubley, M. Winterbottom, and C. McCord, 13 September 2008 . ROM 74922, 20 males 10.7–18.2 mm, 19 females 10.4–17.4 mm, 23 immature 6.6–10.2 mm, Palau, west coast of Babeldaob Island , off Aimeliik coast, 07º28’ 53.9”N, 134º27’28.8”E, Padina on mixed sand substrate, 13.7-19.8 m, rotenone , R. Winterbottom , B. Hubley, A. Bauman, D. Winterbottom, A. Hilman-Kitalong, and L. Pendleton, 19 May 2004 . BPBM 41084 , 2 males 12.7–13.3 mm, 2 females 13.4–13.5 mm, taken with ROM 74922 . CAS 233514 , 3 males 15.4–16.2 mm, 3 females 12.6–14.6 mm, taken with ROM 74922. OMNH- P38332 13.5 mm male, P38333 14.2 mm male, P38334 13.3 mm female, P38335 13.4 mm female, all taken with ROM 74922 . USNM 402735 , 2 males 13.3–14.0 mm, 2 females 12.6–13.7 mm . WAM P.33535-001, 2 males 13.8–15.1 mm, 2 females 12.7–14.3 mm, taken with ROM 74922 .

Other material examined. Eviota pellucida, BPBM 18585, paratypes; BPBM 28893; BPBM 28993; OMNH 35616; Eviota prasites, CAS 233666; Eviota spilota, ROM 74562, ROM 84525.

Diagnosis. The following combination of characters distinguishes E. atriventris from congeners: Abdomen with black peritoneum that is clearly visible externally; dorsal/anal formula 8/7; pectoral-fin rays simple; length of 5 th pelvic-fin ray 40% or greater of 4 th ray; genital papilla in male not fimbriate; cephalic sensory-pore system pattern group 2 (only IT missing).

Description. Dorsal-fin rays VI+I,8 (7[1], 8[29],9[1]); anal-fin rays I,7 (7[30],8[1]); unbranched pectoral-fin rays 14 (13[5], 14[30], 15[7]; fifth pelvic-fin ray 46.3% of 4 th ray (40.0–63.6, 40.3); 3 branches on 4 th ray (3–5); 4–9 segments between consecutive branches of 4 th pelvic-fin ray; 11 branched caudal-fin rays; 17 segmented caudal-fin rays; 23 lateral scale rows (23–24); transverse scale rows 7, embedded cycloid scales on breast; first four spines of dorsal fin filamentous in males, the 4 th the longest, extending to caudal-fin base when depressed; genital papilla in male not fimbriate, bilobed at tip and usually extending to or past first anal-fin ray; cephalic sensory-pore system pattern group 2 (only IT missing).

Measurements (based on holotype and nine paratypes, 13.9–18.2 mm). Head length 31.0 (29.8–33.9, 32.0); origin of first dorsal fin 35.1 (33.9–36.9, 35.7); origin of second dorsal fin 55.5 (54.9–60.1, 56.8); origin of anal fin 55.5 (55.5–66.5, 61.0); caudal-peduncle length 24.4 (24.3–28.4, 25.9); caudal-peduncle depth 15.8 (12.0–15.8, 14.1); body depth 25.4 (22.0–27.2, 24.3); eye diameter 11.1 (10.4–12.9, 11.2); snout length 5.3 (4.3–6.3, 5.3); pectoral-fin length 35.1 (30.7–36.1, 33.6); pelvic-fin length 30.4 (27.4–36.0, 32.0).

Color in preservative of holotype ( Fig. 7 ). Background color of head and body pale yellowish. Abdomen with black peritoneum that is clearly visible externally. A light peppering of small dark chromatophores on ventral half of body, no markings on dorsal half of body. Pectoral-fin base with a band of scattered small dark chromatophores on upper two-thirds. A short line of dark chromatophores extending posteriorly from middle of eye onto opercle. A light peppering of dark chromatophores between eye and upper jaw. Three sharply defined dark lines on snout ( Fig. 8 ). One extending from front of interorbital area down snout to a point in line with front of eyes; one extending from each posterior nostril in front of eye to almost end of snout. A small round dark spot on top of center of upper jaw. Nape just behind eyes with a slight dusky area (most paratypes have distinct lines on the nape extending back from the eyes; one behind the PITO pore and one on each side towards the SOT pores – Fig. 8 ). Pectoral and pelvic fins clear.

Color of fresh holotype ( Fig. 6 ). Background color of head and body red-orange. Abdomen black with a horizontal white line crossing the center of the area. Remainder of lower half of body from anal-fin origin to caudal-fin base dusky. A faint yellowish line just above the vertebral column extending back from the head to the caudal-fin base. A similar shorter line running along the top of the dark abdomen. Eye with a black pupil surrounded by an iris that is golden dorsally and red ventrally; a red-orange line passing through center of eye and a white line below that. Dorsal, anal and caudal fins covered with fine dark chromatophores, red-orange entering onto their bases from the body.

Color in life ( Fig. 1 ). Background color of body a translucent red-orange. Abdomen black with a bright white horizontal line crossing the center of the black area. A narrow golden line running from the top of the head just above the vertebral column back to the caudal-fin base. Anterior end of this line splitting into two lines extending forward to the eyes. A narrow golden line running from the tip of the snout back across the eye just above the pupil and onto the body above the black area of the abdomen, ending at back of black area. Another short, narrow golden line on eye just below pupil. Ventral surface of body from anal-fin origin to caudal-fin base with a narrow golden line. Ventral surface of head and belly a pale translucent cream. Rays of all fins red-orange, membranes with fine dark chromatophores.

Distribution. Known from the Ryukyu Islands-Japan, Palau Islands, Philippine Islands, Indonesia, Papua New Guinea, Solomon Islands, New Caledonia, and the Great Barrier Reef, Australia ( Fig. 9 ).

Etymology. The specific epithet is an adjective combining the Latin atrus (black) and venter (belly), referring to the black pigment in the area of the abdomen.

Comparisons. Eviota atriventris differs from all other species in the genus by its distinctive color pattern of a black abdomen when preserved and in life or fresh with a white line crossing the center of the black area. Eviota atriventris belongs to cephalic sensory-pore group 2, lacking only the IT pore, has simple pectoral-fin rays, a dorsal/anal fin-ray formula almost always 8/7, and the 5 th pelvic-fin ray longer than 30% of the length of the 4 th ray. There are only two other Eviota species that share these characters: E. prasites Jordan and Seale, and E. pellucida Larson and neither have a black abdomen. Eviota pellucida has a modal number of pectoral-fin rays of 16, whereas E. atriventris has a mode of 14 ( Table 1). In addition, E. prasites as a distinctive dark spot at the top of the pectoral-fin base, and E. pellucida may have a less distinctive dusky spot that is lacking in E. atriventris . Eviota prasites often also has a dark spot at the caudal-fin base that is lacking in E. atriventris . In life both E. prasites and E. pellucida may have small red spots on the dorsal and caudal fins, whereas E. atriventris lacks spots. Other described Eviota species in cephalic sensory-pore group 2 that share the above characters except that the 5 th pelvic-fin ray is 10% or less of the 4 th ray instead of being 30% or longer, are E. nigrispina Greenfield & Ssuzuki and E. rubriceps Greenfield & Jewett which both have the ventral half of the entire body dark, E. storthynx Rofen which has a dark postocular spot and the caudal fin crossed by distinct lines of pigment, and E. ancora Greenfield & Suzuki that has five irregular bands of circles of chromatophores crossing the caudal fin and a J-shaped orange mark on the side of the head when alive or fresh.

Prior to the capture of E. pellucida at Ishigaki-jima Island, the Ryukyu Islands, Japan (OMNH-P.35616: Fig. 2 ), this species was only known from the type localities of Guam in the Mariana Islands and Abaiang Atoll in the Gilbert Islands ( Larson, 1976 & Lachner & Karnella, 1980). Therefore E. pellucida at Ishigaki-jima Island is the first Japanese record of the species (New Japanese name: Kojika isohaze). Here it also is recorded from Ponape (USNM 22302 & 223023, pers. comm. Susan Jewett) and Enewetak Atoll, Marshall Islands (BPBM 28893 & 28993) ( Fig. 9 ). All other literature records appear to be E. atriventris . Eviota pellucida is most easily confused with E. prasites and E. spilota . Eviota spilota almost always has a second dorsal-fin count of I,9, whereas it is almost always I, 8 in E. pellucida . Eviota prasites has a distinctive dark spot at the top of the pectoral-fin base whereas there only may be a dusky area there in E. pellucida . Eviota prasites also has a dusky spot at the bottom of the caudal-fin base that is lacking in E. pellucida . Finally, in life E. prasites has seven white blotches extending along the side just above the red area over the vertebral column, the first starting above the two white blotches on the pectoral-fin base ( Fig. 10 ), whereas there are eight in E. pellucida ( Figs. 3 & 4 ).

Figures

FIGURE 1. Underwater photograph of Eviota atriventris, Flores. Photograph by J.E. Randall.

FIGURE 2. Eviota pellucida, OMNH 35616, Ishigaki-jima Island, Ryukyu Islands, Japan. Photograph by T. Suzuki.

FIGURE 3. Underwater photograph of Eviota pellucida, male, Amami-oshima Island, the Ryukyu Islands, Japan. Photograph by H. Kanehara.

FIGURE 4. Underwater photograph of Eviota pellucida, female, Amamki-oshima Island, the Ryukyu Islands, Japan. Photograph by H. Kanehara.

FIGURE 6. Eviota atriventris, fresh holotype, ROM 76339, 17.1mm SL. Photograph by R. Winterbottom.

FIGURE 7. Eviota atriventris, preserved holotype, ROM 76399, 17.1 mm SL. Photograph by D.W. Greenfield.

FIGURE 8. Eviota atriventris, head of CAS 233514, paratype, 13.5 mm female. Photograph by D.W. Greenfield.

FIGURE 9. Distribution of Eviota atriventris (circles) and E. pellucida (squares).

FIGURE 10. Underwater photograph of Eviota prasites, male, Amami-oshima Island, the Ryukyu Islands, Japan. Photograph by H. Kanehara.