Eviota fallax, Greenfield, David W. & Allen, Gerald R., 2012

Greenfield, David W. & Allen, Gerald R., 2012, Eviota fallax, a New Dwarfgoby from the Western Pacific (Teleostei: Gobiidae), Zootaxa 3522, pp. 42-48 : 42-47

Eviota fallax n. sp.

Twin Dwarfgoby ( Figs. 1–8)

Eviota albolineata (non-Jewett & Lachner) Kuiter & Tonozuka 2001: 701. Eviota species 8 Senou, et al. 2004: 148.

Holotype: MZB 20888, 18.1 mm, male, Indonesia, WA, West Papua, Pulau Lemon, small island near Manokwari, 00°53’S, 134°05’E, 5–20 m, station CB-08-01, G.R. Allen & M. Erdmann, May 11, 2008.

Paratypes: WAM P33050.002, 18.2 mm, male, 14.0, 14.1, & 17.9 mm females, Indonesia, WA, West Papua, Cenderawasih Bay, 02°25’S, 134°13’E, 5–12 m, station CB-08-012, G.R. Allen & M. Erdmann, November 14, 2008; WAM P33039-009, 13.6 mm male, six females 11.7–16.2 mm, taken with holotype; CAS 234442, 15.1 mm male, 17.0 mm female, taken with holotype; ROM 93604, 16.2 mm male, 16.1 mm female taken with holotype.

Other material examined. Eviota fallax non-types: BPBM 38794 (1) Satonda Island, Indonesia; BPBM 38646 (1) Komodo Group, Rinca, Indonesia; BPBM 39028 (1) New Britain, Kimbe Bay. These specimens were incorrectly referred to as E. melasma in Greenfield & Randall (2010). Eviota melasma : USNM 227317 (10), Australia, Great Barrier Reef, Lizard Island; USNM 227318 (6), Australia, Great Barrier Reef, Lizard Island.

Diagnosis. The following combination of characters distinguishes E. fallax from congeners: a dark occipital spot, more well-developed in males and in preservation; a single orange spot behind the eye in life; cephalic sensory-pore system pattern Group I (complete); dorsal/anal formula usually 9/8; eye diameter 26.7–34.4% HL; caudal-peduncle depth 10.9–12.4% SL; 4th pelvic-fin ray with short, thick branches bound together by membranes.

Description. Dorsal-fin rays VI+I,9 (9[9],10[1])); anal-fin rays I,8; pectoral-fin rays 17 (16[1], 17[9]), rays 11–16 branched in holotype; fifth pelvic-fin ray 10% (0–10%) of 4th ray; 5 short branches on 4th ray (4–7), bound by membranes; 2 (2–4) segments between consecutive branches of 4th pelvic-fin ray; 12 branched caudal-fin rays; 17 segmented caudal-fin rays; 25 (24–25) lateral scale rows; transverse scale rows 6; second spine of first dorsal fin filamentous in male holotype, extending back to third element of the second dorsal fin; genital papilla in male not fimbriate, trilobed at tip and usually extending to or past first anal-fin ray; cephalic sensory-pore system pattern Group I (complete).

Measurements (based on holotype and nine paratypes, 14.0– 18.1 mm). Head length 28.9 (27.7–32.9, 28.9); origin of first dorsal fin 33.3 (31.8–35.7, 34.1); origin of second dorsal fin 55.1 (53.2–55.3, 54.8); origin of anal fin 58.4 (55.8–61.3, 59.0); caudal-peduncle length 24.8 (24.5–28.3, 25.8); caudal-peduncle depth 11.8 (10.9–12.4, 11.6); body depth 18.7 (16.6–19.0, 17.6); eye diameter 7.7 (7.7–9.6, 8.9); snout length 3.4 (2.9–4.5, 3.9); pectoralfin length 33.6 (30.0–36.3, 33.4); pelvic-fin length 28.6 (23.6–31.1, 27.9).

Color in preservative of holotype ( Fig. 1). Background color of head and body pale yellowish. The only bold dark marking on the body is a black occipital spot slightly less than the diameter of the pupil, better developed in males. A peppering of small melanophores on the top of the head behind the eyes and a row of similar spots behind the eye running along the top of the opercle. Anterior tubular nares with a few small melanophores. A very light peppering of small melanophores on the pectoral-fin base, mostly concentrated at its center. Ventral surface of the abdomen from the pelvic-fin bases to the anus peppered with small melanophores. First dorsal fin peppered with small melanophores on distal three-quarters. Entire second dorsal, anal and caudal fins peppered with small melanophores. Pectoral and pelvic fins with just a few small melanophores.

Color in life ( Fig. 2 —Cenderawasih Bay). Background color of head and body translucent white. Scale margins over most of the body orange. Three orange blotches over the abdomen separated by white blotches. A single, large orange blotch behind the eye and a series of narrow orange dashes running back from it along the backbone and a series of seven white dashes spaced between them. A white blotch present above the pectoral-fin base and at the caudal-fin base, and a series of small white spots running along the dorsal-fin bases. Head with a white line in front of the eye that continues behind it over the opercle A white line is present on the top of the head between the two orange blotches behind the eyes. Operculum and snout reddish, underside of head translucent white. Pupil of eye black, surrounded by a white ring, the iris dark brown and crossed by several spoke-like white lines. Dorsal and caudal-fin elements orange. Occipital spot not obvious in Cenderawasih Bay photograph, but obvious in a Kimbe Bay photograph of a male ( Fig. 3 ).

Distribution. Known from Ie, Kume, and Iriomote Islands in the Ryukyu Islands, Japan ( Senou et al. 2004); Bali and Sangihe Island, Indonesia ( Kuiter &Tonozuka 2001), West Papua, Pulau Lemon and Satonda Island, Indonesia; and Kimbe Bay, New Britain. In addition, the second author has observed and photographed the species at the Solomon Islands ( Fig. 4 ), Banda ( Fig. 5 ), Indonesia, and several localities in Micronesia including Yap ( Fig. 6 ), and Ngulu Atoll ( Fig. 7 ).

Etymology. The specific epithet is from the Latin fallax (deceitful, false) referring to its superficial similarity to Eviota natalis , and is treated as a noun in apposition.

Comparisons. Although E. fallax has a live coloration that is very similar to E. natalis , when preserved specimens are examined it is evident that it has a dark occipital spot that is lacking in E. natalis . Eviota fallax has a complete cephalic sensory-pore system (Group I of Lachner and Karnella 1980), bringing the number of species in this group to 26 ( Greenfield and Randall 2010). Eviota fallax has a dorsal/anal formula of 9/8, and the only other species in Group I with that formula and that also have a single, prominent dark occipital spot are E. karaspila Greenfield and Randall 2010 , E. melasma Lachner and Karnella 1980 , and E. smaragdus Jordan and Seale 1906. Eviota karaspila has a very different live coloration, with a light body lacking strong pigmentation and the dark occipital spot very obvious. In addition, it has a larger eye (33.7–39.9, 36.7% HL) versus (26.7–34.4, 30.7 % HL) in E. fallax , a character that was useful in separating E. karaspila from E. melasma ( Greenfield and Randall 2010, Fig. 7 ). Eviota smaragdus has a much deeper caudal-peduncle (13.4–14.9, 14.1) versus 10.9–12.4, 11.6 in E. fallax ( Greenfield & Randall. 2010) . The photographs of live E. smaragdus in Senou et al. 2004 (pg. 127) are quite different from those of E. fallax (sp. 8, pg. 148). Eviota fallax is most similar to E. melasma in both eye size and caudal-peduncle depth, but it differs from this species in the structure of the fourth pelvic-fin rays. The pelvic-fin rays in E. melasma are longer, more slender, and not connected by membranes, whereas those of E. fallax are shorter, thicker, and bound together by membranes ( Fig. 8 ). The pelvic-fin rays of E. karaspila are more similar to those of E. melasma . Eviota fallax also differs in live coloration from E. melasma , with a single orange spot behind the eye in E. fallax ( Figs. 2–7 ), whereas there are two in E. melasma , ( Figs. 9 & 10 ).

Remarks. In Japan this species occurs in depths of 15–31 m in rocky caverns or coral heads on sand ( Senou et al. 2004). The second author has seen it most frequently at depths of about 8–15 m on either live coral (frequently faviids) or on rocky surfaces covered with coralline algae patches. In our comparison of E. fallax with E. melasma we used specimens of E. melasma from the Barrier Reef of Australia, the type locality, because of color variations in that species from various other locations.

Figures

FIGURE 2. Eviota fallax, underwater photograph, Cenderawasih Bay, West Papua, Indonesia. Photograph by G. R. Allen.

FIGURE 3. Eviota fallax, underwater photograph, Kimbe Bay, New Britain (BPBM 39028). Photograph by J. E. Randall.

FIGURE 4. Eviota fallax, underwater photograph, Solomon Islands. Photograph by G. R. Allen.

FIGURE 5. Eviota fallax, underwater photograph, Banda. Photograph by G. R. Allen.

FIGURE 6. Eviota fallax, underwater photograph, Yap. Photograph by G. R. Allen.

FIGURE 7. Eviota fallax, underwater photograph, Ngulu Atoll. Photograph by G. R. Allen.

FIGURE 8. Fourth pelvic-fin ray. A. Eviota fallax, paratype, WAM P. 33039.009, 16.2 mm. B. Eviota melasma, USNM 227318, 17.5 mm. Photographs by D. W. Greenfield.

FIGURE 9. Eviota melasma, Heron Island, Australia (Fig. 3, Greenfield & Randall, 2010). Photograph by J. E. Randall.

FIGURE 10. Eviota melasma, Lizard Island, Australia (Fig. 4, Greenfield & Randall, 2010). Photograph by A. Gonzáles- Cabello.