Eviota bipunctata

Greenfield, David W. & Jewett, Susan L., 2016, Two new dwarfgobies from the Indian and Western Pacific Oceans (Teleostei: Gobiidae: Eviota), Zootaxa 4121 (5), pp. 589-599 : 595-599

Eviota bipunctata n. sp

Twinspot Dwarfgoby Figs. 7–11

Holotype. USNM 225176, 14.0 mm male, Philippine Is., Palawan Province, NW side of Putic Id., 10°55’05” N, 121°02’03”E, 0–4.6 m, field number SP 78-18, 22 May 1978, V.G. Springer and Smithsonian Philippine Exp. Team.

Paratypes. All from PHILIPPINE ISLANDS. The following 4 lots with the same collection data as holotype: USNM 225175, 5 (14.2–17.0); CAS 47920, 2 (15.3–15.6); AMS I.22210-001, 2 (15.8–17.0); ANSP 146760, 2 (15.4–17.2). The following 4 lots have the same collection data: USNM 225174, 9 (11.6–13.1), Negros Oriental, Maloh, 0–3.1 m, LK 79–19, 18 May 1979, H.A. Fehlmann; CAS 47919, 1 (13.9); AMS I.22207-001, 2 (12.4– 13.5); USNM 225173, 1, (11.9). USNM 225171, 3 (13.0–14.7), Mindanao, Zamboanga del Norte, W. side of Solino Id., 0–4.6 m, LK 79-7, 3 May 1979, L. Knapp; USNM 225170, 4 (13.7–15.4), Cuyo Is., Cocoro Id., 0–3 m, SP 78-26, 26 May 1978, V.G. Springer & team; BPBM 26540, 1 (12.8), Negros Id., S.E. coast at Ajong, 0–2.4 m, SP 78-37, 8 June 1978, V.G. Springer & J.D. Libbey. USNM 225172, 1 (17.2), Negros Oriental, Vic Port Siyt, 0–2 m, SP 78-44, 14 June 1978, L.W. Knapp et al.

Nontype material. TAIWAN. BPBM 23315, 2 (12.2–15.8), S. end at Truan Fan Shih, 0–6 m, J.E. Randall. MARIANAS ISLANDS. USNM 225182, 2 (10.0–11.2), Saipan, P.E. Cloud. CAROLINE ISLANDS. SOROL ATOLL-CAS 47877, 1 (10.7), W. of Bigelliwol Id., 0–3 m, GVF Reg. 993, sta. 196, A.W. Scott; CAS 47880, 1 (10.1), Sorol Id., 0–3 m, GVF Reg. 989, sta. 192, A.W. Scott; IFALUK ATOLL-CAS 47878, 1 (12.0), between Falarik & Elangalap Id., 0–2.1 m, GVF Reg. 129, sta. 8, R.R. Harry. CAS 47879, (12.1), N. end Falarik Id., 0–1.5, GVF Reg 152, sta. 31, R.R. Harry; CAS 47881, 3 (9.9–12.9), Falarik Id., 0.9–3 m, GVF Reg. 122, sta 1, R.R. Harry; USNM 224971, 3 (10.6–13.0), Ponape Id., 0–3.6 m, VGS 80-5, V.G. Springer; USNM 224972, 3 (8.9–11.5), (0–0.9), VGS 80-15, V.G. Springer. PAPUA NEW GUINEA. USNM 225179, 1 (12.1), Muschu Id., off Wewak, 0– 1.2 m, B.B. Collette, 1709; USNM 225177, 2 (12.2–12.7), Umboi Id., 0–4.5 m, B.B. Collette, 1699; USNM 225178, 2 (12.9–14.0), Louizade Archipelago, SW shore Panapompom Id., 0–6 m, B.B. Collette, 1693. INDONESIA. USNM 225181, 5 (11.0–14.8), Java Sea, Bawean Id., 0.0– 3.6 m, VGS 74-27, V.G. Springer. WESTERN AUSTRALIA. WAM P.25374-037, 2 (16.8–17.2), NW Cape, lagoon off Tantabiddi CK, 0–4 m, G. Allen. SEYCHELLE ISLANDS ( IIOE Exp. Of 1964). Mahe—ANSP 146503, 65 (8.4–16.2), N. of Anonyme Id., 0–2.7 m, F-17; ANSP 146500, 1 (13.9), 0–2.7), F-13 or F-17; ANSP 146497, 26 (8.9–16.1), Anonyme Id., 0–2.7 m, F-37; ANSP 146504, 9 (10.7–14.7), N. of Anonyme Id., 0–1.5 m, F-23; AMS I.22202-001, 10 (9.8–14.5), NW Bay, 0–4.6 m, F-36; CAS 47918, 4 (11.1–15.2), inshore of Souris Id., 0–1.5 m, F-53; USNM 225183, 22 (11.2– 16.2), Curieuse Id., 7.6 m, F-67; Praslin Id.— ANSP 146502, 5 (9.7–13.6), between Praslin & Round Ids., 7.6 m, F- 59; ANSP 146499, 13 (10.1–15.3), SE corner, 3–39.1 m, F-5; USNM 209226, 1 (13.0), paratype of E. stigmapteron Smith, La Digue Id., J.L.B. Smith. AMIRANTES ISLANDS: ANSP 146501, 4 (9.9–14.5), D’Arros Id., 0–2.1 m, F-91; ANSP 146498 1, (8.6), African Is., SE of South Id., 0–4.6 m, F-75; ALDABRA: USNM 225180, 3, (12.9– 13.3), S. of La Passe du Bo;is, 0–3 m, H.A. Felman, 67-61.

Diagnosis. The following combination of characters distinguish E. bipunctata from congeners: cephalic sensory-pore system pattern 2 (lacking only the IT pore); some pectoral-fin rays branched; pectoral-fin base with 1 or 2 prominent dark spots; dorsal/anal-fin formula usually 8/8; no occipital spots.

Description. Dorsal-fin elements VI-I,7 [1], VI-I,8 [26], VI-I,9 [4], first dorsal fin rounded in shape, 2nd spine longest, none filamentous, all second dorsal-fin soft rays branched except first soft ray, last ray branched to base; anal-fin elements I,7 [3], I,8 [27], I,9 [1], all soft rays branched, last ray branched to base; pectoral-fin rays 15 [7], 16 [22], 17 [2], some branched, reaching base of 1st soft dorsal-fin ray in paratype; pelvic-fin rays I,4 [13], I,4 + a rudiment [6], I, 4 1/10 [12]; branches on 4th pelvic-fin ray 7–16, average 10.8; segments between consecutive branches of 4th pelvic-fin ray 0–3, average 1.1; pelvic-fin membrane reduced; branched caudal-fin rays 11[(2], 12 [8], 13 [14]; segmented caudal-fin rays 16 [3], 17 [27]; lateral scale rows 23 [4], 24 [13], 25 [3], 26[(1]; transverse scale rows 6[(2], 7 [4], area under first half of dorsal fin naked, scales on body finely ctenoid, breast scaleless; vertebrae 10 [9] precaudal plus 16 [9] caudal, total 26; pelvic fin usually not extending to anal-fin origin, never beyond. Cephalic sensory-pore system lacking only the IT pore (pattern 2) ( Fig. 7 ); cutaneous papilla system pattern B. Male urogenital papilla not fimbriate although fringing at tip often longer than typical and may be confused with female papilla ( Fig. 8 ). Front of head rounded with an angle of about 60° from horizontal axis; mouth slanted obliquely upwards, forming an angle of about 65° to horizontal axis of body, lower jaw not projecting; maxilla extending posteriorly just past anterior edge of pupil in holotype, past posterior edge of pupil in some paratypes; anterior tubular nares short, not reaching margin of upper lip; gill opening extending forward to below posteroventral edge of operculum.

Measurements (based on holotype and 9 paratypes, 13–15.0 mm). Head length 28.7 (27.3–28.9, 28.0); origin of first dorsal fin 33.9 (30.9–38.3, 35.2), lying behind posterior margin of pectoral-fin base; origin of second dorsal fin 55.0 (55.0–61.6, 57.4), slightly in advance of anal-fin origin; origin of anal fin 57.8 (57.8–63.8, 60.5); caudalpeduncle length 22.1 (21.1–27.7, 23.6); caudal peduncle moderate depth 13.9 (11.6–14.9, 12.9); body depth slender 19.3 (17.0–22.0, 19.8); eye diameter 9.3 (8.5–10.1, 9.3); snout length 4.6 (2.3–4.6, 3.8); pectoral-fin length (23.0– 36.1, 32.1); pelvic-fin length (23.0–33.9, 27.6).

Color in preserved specimens ( Figs. 9–11 ). The color pattern is described for males and females from the Philippine Islands, with geographic variation from this pattern discussed in the Remarks section. Most males have two intense dark spots on fleshy pectoral-fin base although some have one large intense dark spot appearing as though two spots merged; large dark spot may consist of densely packed or rather loosely arranged chromatophores or upper portion may be less dense than lower portion of spot. All four conditions may be found in single collection ( Fig. 11 ). Females also may have two spots on pectoral-fin base, lower always more intense, or may have spot or only few chromatophores restricted to lower portion of base; also may have single large spot of loosely arranged chromatophores or one with lower portion more intense. Pectoral-fin base spots in females generally less intense than males, with tendency to lose upper spot. Cheek and operculum may have four to five patches of large loosely arranged chromatophores or may be entirely or nearly pale; cheek and operculum markings may continue to underside of head; dorsal portion of head and nape usually unpigmented but some specimens have small chromatophores loosely arranged in irregular transverse markings. Scale pockets heavily pigmented over body, least developed anteriorly, absent on belly region, and most heavily developed on caudal peduncle. Faint brownish chromatophores may occur uniformly over lower three fourths of body. Six spots along ventral midline of body posterior to anal-fin origin (postanal spots) and six comparatively wide, subcutaneous bars on lower body associated with midline spots: sixth bar darkest, central portion forming moderately developed subcutaneous caudal peduncle spot; fourth and fifth lower bars merge dorsolaterally forming one bar making five upper and six lower subcutaneous bars. Two broad subcutaneous bars in belly region extending entire depth of body, and inconspicuous subcutaneous bar on upper body above pectoral-fin base. Pigmentation of dorsal fin variable. Spinous dorsal fin of some males with weak dusky horizontal stripe near base, outer portion of fin pale, second dorsal fin of these specimens with weak dusky pigmentation near base and outer two thirds of fin pale; other specimens have eleven to twelve dark spots along dorsal midline of body and these spots extend into basal portion of both dorsal fins, continuing in some to distal portions of second dorsal fin as dusky streaks. Dorsal-fin pigmentation reduced in intensity and development, or sometimes lacking in females. Anal fin blackish with very narrow pale margin, much darker than other fins. Caudal fin lightly dusky basally, most of distal portion pale, posterior margin light dusky. Pectoral and pelvic fins pale or nearly so.

Distribution. This species occurs from Aldabra and the Seychelles in the Indian Ocean eastward to Ponape, Caroline Islands, northward to Taiwan and southward to Papua New Guinea, absent on the Great Barrier Reef but taken at the Northwest Cape, Western Australia.

Etymology. The specific epithet is a compound adjective from the Latin words bi (two) and punctum (dot/spot) in reference to the two dark spots on the fleshy pectoral-fin base.

Comparisons. As discussed for E. asymbasia above, of the 35 species of Eviota with cephalic sensory-pore system pattern 2 (lacking only the IT pore cephalic), only eight others have branched pectoral-fin rays and a dorsal/ anal formula of 8/8: E. asymbasia (this paper), E. dorsimaculata , E. indica , E. lacrimosa , E. latifasciata , E. piperata , E. rubra , and E. shibakawai . The following species lack the dark spots on the pectoral-fin base present in E. bipunctata : Eviota dorsimaculata , E. indica , E. latifasciata , E. shibukawai , and E. rubra . Eviota bipunctata lacks distinct lines radiating down from under the eye, whereas such lines are present in E. asymbasia , E. lacrimosa , and E. piperata . Eviota queenslandica usually has a D/A of 9/8, but can have counts of 8/8, but is has an occipital spot that is lacking in E. bipunctata .

Eviota bipunctata superficially resembles E. monostigma when the spot on the pectoral-fin base covers the entire base or E. distigma when it has two, but both have a complete cephalic sensory-pore pattern (pattern 1), whereas E. bipunctata has pattern 2, lacking the IT pore.

Remarks. A paratype of E. stigmapteron Smith , a synonym of E. distigma , received on exchange from the J.L.B. Smith Institute of Ichthyology, USNM 209226, is E. bipunctata . Eviota distigma has a complete cephalic sensory-pore system, whereas E. bipunctata lacks the IT pore.

Eviota bipunctata is unusual because it shows greater variation in pectoral-fin base coloration unrelated to sex than any other species of Eviota that we are aware of. Had these differences occurred in specimens from specific geographic localities we might have thought them to be indicative of different species, but as shown in Fig. 11 , the full range of variation has been found in single lots both in the Indian and Pacific Oceans; however, because of its wide geographic range, it is likely that more than one species is involved. The availability of information on live coloration and DNA has shown this to be the case in a number of species of Eviota , but that information is not available for E. bipunctata . There are however some pigmentation differences between populations: Indian Ocean specimens tend to lack scale pocket pigmentation and the spinous dorsal fin is dusky throughout, whereas the pockets are stronger and dorsal fin different in populations from the Philippines, Taiwan, Indonesia and Papua New guinea. We have restricted our type material to specimens from the Philippine Islands.

Figures

FIGURE 7. Cephalic sensory-pores of E. bipunctata holotype, USNM 225176. Photograph by D. W. Greenfield.

FIGURE 8. Male urogenital papilla of E. bipunctata holotype, USNM 225176. Photograph by D. W. Greenfield.

FIGURE 9. Eviota bipunctata holotype, USNM 225176. Photograph by D. W. Greenfield.

FIGURE 10. Eviota bipunctata, ANSP 146503, 13.7 mm male, Seychelles Islands. Drawing by J. R. Schroeder.

FIGURE 11. Eviota. bipunctata pectoral-fin base color variation-ANSP 146497, Seychelles Islands, A— 14.7 mm male, B— 14.7 male, C— 13.4 male, D— 12.7 female, E— 15.0 female. Photograph by D. W. Greenfield.