Trimma okinawae ( Aoyagi, 1949 )

Winterbottom, Richard & Hoese, Douglass F., 2015, A revision of the Australian species of Trimma (Actinopterygii, Gobiidae), with descriptions of six new species and redescriptions of twenty-three valid species, Zootaxa 3934 (1), pp. 1-102 : 66-70

Trimma okinawae ( Aoyagi, 1949)

Orange-red Pygmygoby

Figs. 37–38 , Pl. 3 B

Eviota caesiura okinawae Aoyagi, 1949:173 (Itoman, Okinawa-Honto, Japan).

Trimma okinawae: Masuda et al., 1984 :pl. 237; Shao et al., 1992:331; Allen, 1993: 88 ( Ashmore Reef, Scott Reef, Rowley Shoals off WA); Masuda & Allen, 1987:419; Allen, 1997:218 ( Australia); Randall et al., 1997:408; Yano, 1998:70; Myers, 1999:pl. 163; Hayashi & Shiratori, 2003:35 (x 2); Allen et al., 2004:329; Kuiter & Tonozuka, 2004:704 (x 2); Senou et al., 2004:104 –105 (x 5, Japan); Aizawa, 2006:8 ( Japan); Hoese & Larson, 2006:1690 (in part, Coral Sea and Timor Sea); Satapoomin, 2007:162 ( Thailand); Allen & Erdmann, 2012:943 ( Vietnam and Japan to Marshall Id, and Australia). Trimma sp: Burgess et al., 1990:577; Hayashi & Shiratori, 2003:44,:45 (both from Saipan).

Australian material. Queensland: Portlock Reef: AMS I.33752-058, 4(15–16), 12– 16 m. Boot Reef: AMS I.33747-036, 10(10–19), 20 m. Ashmore Reef: AMS I.33717-079, 6(8–18), 1–32 m; AMS I.33720-058, 19(10–16), 2–32 m; AMS I.33724-035, 3(14–16), 9–25 m; AMS I.33728-039, 31(11–17), 11–15 m; AMS I.33731- 0 90, 29(10–22), 18 m; AMS I.33738-091, (19), 4–24 m;. Raine Id: AMS I.20757-082, 4(15–22), 22 m; AMS I.20775-058, 4(15–22), 0–20 m; AMS I.20775-126, 5(17–19), 0– 20 m. Escape Reef: AMS I.22620-016, 2(18–20), 38– 50 m. Osprey Reef, Coral Sea: AMS I.25109-71, 2(18–19), 1–3 m; AMS I.25110-39, 19(9–22), 2–8 m; AMS I.25112-033, 45(11–26), 1–15 m; AMS I.25113-046, 46(14–22), 9– 11 m. Western Australia: Shark Bay: WAM P.26671-005, 2(22–23). Off Tantabiddi Creek: WAM P.25367-017, 3(20–24), 10 m; WAM P.25369-015, 8– 10 m. Northwest Cape: AMS I.19641-021, 1(23), 8– 10 m. Kendrew Id, Dampier Archipelago: WAM P.25108-038, 1(21); WAM P.25111-030, 2(25–26). Scott Reef: AMS I.21315-018, 1(19), 2–3 m; AMS I.25107-061, 11(17–24), 25 m; AMS I.26740-018, 1(17), 20–25 m; AMS I.21318-038, 11(12–20), 0–3 m; NTM S.11315-035, 5(13–21), 6–15 m; NTM S.11370-028, 5(15–26), 18–20 m; NTM S.11371-054, 37(16–22), 2–5 m; NTM S.11373-048, 5(13–16), 22–25 m; NTM S.11387-018, 3(18–21), 7– 22 m. Ashmore Reef, Timor Sea: AMS I.26742-030, 2(19–19), 15–16 m; AMS I.26746-014, 2(16–19), 15–18 m; NTM S.12318–062, 50(8–24), 14–16 m; NTM S.12328-028, 15(15–21), 19–20 m; NTM S.12331-023, 15(11–24), 20– 21 m. Cartier Id., Timor Sea: AMS I.26752-017, 14(14–22), 12 m.

Other material. Because this species is so similar to Trimma readerae , sp. nov., which we only recently recognized, we list here only material that we have examined after 2013. Numerous records including those in the literature may well relate to Trimma readerae n.sp.

Vietnam: Nha Trang: ROM 73190, 4(9–23), 0– 14 m. Japan: Miyake-jima: BPBM 19011, (21). Iriomote Id: NTM S.12112-002, (13), 1–2 m; NTM S.12116-008, (13), 2–3 m; NTM S.12125-003, (14), 12 m; NTM S.12137- 0 0 2, 4(15–19). Okinawa: BLIH 1970181, 2(19–20). Taiwan: southwest of Yeh-Liu: USNM 263419, 10(19–26), 8– 11 m. Philippines: El Nido: LICPP 1983345, (23). Sombrero Id: AMS I.21908-012 2(18–22), 1–34 m; AMS I.21915-057 4(18–22), 6 m. Bolinao: AMS I.21903-015, 38(12–20), 3– 15 m. Indonesia: Off Wailiti 11km NW of Sao Wisata Resort, Flores: AMS I.34501-077, 6(12–19), 12 m. Papua New Guinea: Manus Id: WAM P.27824- 0 37, 12(12–21), 19– 20 m. Solomon Ids: Florida Id: AMS I.17529-004, (20), 35 m; AMS I.17499-024, 6(17–23), 8–12 m; AMS I.17492-031, 2(17–18), 2– 20 m. Guadalcanal: AMS I.17524-007, (19), 35 m. Santa Cruz Ids: AMS I.39010-090, 4(20–26), 0–35 m; AMS I.39032-050, (17), 25–35 m; AMS I.39012-044 5(10–21), 10–35 m; AMS I.39013-096, 2(14–15), 1–11 m; AMS I.39017-058, (17), 10–30 m; AMS I.39007-044, 3(18–25), 0–33 m; AMS I.39039-108, 2(15–17), 0–10 m; AMS I.39040-069, 6(21–25), 10– 30 m. Vanuatu: Futuna Id: AMS I.20792-038 (15), 5– 8 m. Rowa Id, Banks group: AMS I.37928-030 2(18), 1– 7 m. Fiji: Suva: AMS I.18354-066, 21(14–23), 6 m. New Caledonia: Seche Croissant: ROM 64325, (20), 8–11 m; Isle Redika: ROM 64327, 35(11–25), 6– 11 m. Marshall Ids: Eniwetok Atoll: AMS I.37706-007, 3(17–20), 5–8 m; AMS I.39633-006 (16). Kiribati: Abaiang Atoll: AMS I.18044-044, 16(9–21), 5–9 m; AMS I.18051-056, 4(16–19), 8– 11 m. Samoa: Tutuila: AMS I.21992- 0 0 1, 9(15–20), 36 m; BPBM 17499, 4(18–23), 30– 38 m.

Diagnosis. A species of Trimma with a deep interorbital trench, a moderately deep groove behind the upper half of the eye in adults; the predorsal midline almost completely covered with ctenoid scales in 5–7 rows extending anteriorly to just behind the interorbital trench, the anterior-most scale just behind a small naked patch and not distinctly larger than the second scale on the midline; opercle and preopercle naked; pectoral-fin base covered with 10–12 large cycloid scales in 3–4 vertical rows, with the lowermost 3–4 scales smaller than the other scales; prepelvic area with a small scale covering the basal membrane, followed anteriorly by a large scale between the bases of the fins and 3 rows of large of cycloid scales in the midline anterior to this; upper pectoral rays unbranched, central 4–9 rays branched, lower rays unbranched; pelvic fins connected only at their bases with one or two scales in the midline extending anterior to the connecting membrane, widely separated, the distance between the bases of the fins about three–quarters of the base of each pelvic fin; fifth pelvic ray usually unbranched (one branch in about one third of the adults), fifth ray 40–70% the length of the fourth; second and third dorsal spines longest, not elongated into a filament in females, second spine often elongated as a short filament in males; second dorsal usually I 9 and anal rays usually I 8; nape crest prominent, extending to above the posterior preopercular margin, midline of the crest scaleless; a yellow to red bar extending across the cheek from just behind the middle of the eye, from almost vertical to sloping slightly posteroventrally, the bar less than pupil diameter in width; a more-or-less vertical narrow light yellow to red bar on the posterior part of the preopercle; and the body with small yellow to red spots in 4–5 irregular rows anteriorly and 3 rows on the caudal peduncle.

Description. The description is primarily based on specimens from the Coral Sea and Western Australia. Dorsal fin usually VI + I 9 (I 8 or I 10 in 7% of individuals), mean = 9.1, n = 110, second spine longest, in some specimens elongated into short filament (reaching first segmented rays of second dorsal fin in some males); first ray of second dorsal fin usually unbranched (unbranched in specimens <14 mm SL, but also unbranched in about two-thirds of adults), anterior element of last element branched; anal fin I, 8 (rarely I 7 or I 9, in 6% of individuals), mean = I 7.9, n = 110, first ray usually branched (often unbranched in specimens <14 mm SL), anterior element of last ray branched; pectoral-fin rays usually 18–19, ( Australia and Solomon Islands mean = 18.3, n = 92, Japan and Taiwan mean = 18.1, n = 17), upper 5–8 rays unbranched, central 4–9 rays branched and lower 6–11 rays unbranched; pectoral fin reaching just posteriorly to vertical in line from urogenital papilla to about second segmented ray of anal fin; pelvic fin I 5, fins widely separate with short basal membrane, covered by median scale, distance between bases of fins slightly less than base of each pelvic fin; first four rays with one sequential branch, fifth ray with one dichotomous branch (two terminal tips) or unbranched, 50–70% length of fourth ray, which reaches posteriorly to below point between anal spine and second segmented anal ray, segmented caudal rays usually 17; branched caudal rays usually 6 upper + 5 lower (rarely 6+ 6 in about 6% of specimens); predorsal scales on midline 3–6, anterior two scales on midline, posterior scales overlapping midline and no scales on midline covering nuchal crest (predorsal scales mean Coral Sea = 3.1, n= 34, mean Western Australia = 3.8, n = 37, mean Japan and Taiwan = 3.2, n = 10); lateral scales 22–24, usually 23 or 24 (mean Coral Sea = 23.2, n = 49, mean Western Australia = 23.8, n = 26, mean Japan and Taiwan = 23.4, n = 8); transverse scale count 6–8, usually 7 (mean Coral Sea = 7.0, n = 33, mean Western Australia = 6.9, n = 23, mean Japan and Taiwan = 7.0, n = 6); no scales on preopercle or opercle; scales extending to edge of postorbital trench above posterior part eye; scales below second dorsal fin with small accessory scales; pectoral-fin base covered with 5–6 large cycloid scales, lowermost 3–4 scales smaller than others; prepelvic area fully scaled, with small scale covering basal membrane between two pelvic fins, followed anteriorly by large scale between bases of fins and 3 rows of large of cycloid scales anteriorly. Teeth in lower jaw consist of enlarged outer row of curved, slightly enlarged, spaced canines ending near bend in dentary and inner row of similar, but smaller canines extending full length of dentary, with one or two irregular rows of smaller conical teeth in between; outer row of teeth in upper jaw wide-set and extending full length of premaxilla, similar to those of lower jaw, with 1–2 small irregular inner rows of teeth, innermost row, not enlarged. Tongue tip slightly concave. Gill opening extending anteroventrally to below posterior margin of pupil; outer gill rakers on first arch very elongated, almost equal to filament length at angle 2–4 + 10–14 = 14–19 (n = 28, mean = 16.5). Anterior nares at end of narrow tube, just above upper lip, posterior nares small pore with raised rim about two pore diameters from anterior and two pore diameters from eye; nasal sac elevated as raised oval sac located just above upper lip. Interorbital very narrow, with eyes almost touching, trench typically present in well preserved adults, but often obscured in poorly preserved specimens and not well developed in juveniles <18 mm SL.

Colour pattern. Freshly collected specimens from Western Australia (from slides of freshly collected specimen from Kendrew Island and Shark Bay – Fig. 37 A). Head with large yellow to yellowish-orange, irregularly shaped spots and bars, bordered by white rim; vertical band of same colour, less than pupil diameter, extending from below anterior pupil margin to upper jaw and similar shaped band below posterior margin of pupil extending to beyond posterior end of jaws, interspace between two bands grey to bluish-grey; spots near posterior preopercular margin normally joined into thin vertical bar extending upward to behind eye or sometimes separated into separate spots; snout usually grey, with small yellow to yellowish orange spot at anteroventral margin of eye; pale yellowishorange vertically elongate spot ventrally on opercle and similar spot near dorsal margin of opercle; two small round yellowish-orange spots ventrally on branchiostegal membranes below opercle and preopercle (absent in some populations), pale orange vertically elongate spot ventrally on opercle; pectoral-fin base with upper and lower yellow-orange large spot, with two spots almost touching; nape with large yellowish-orange spots, some connected across nape forming bars; yellow to reddish-orange spots on body vertically elongate, but becoming smaller posteriorly and ventrally, spots usually not forming distinct horizontal rows on caudal peduncle; dorsal and anal fins with large spots of similar colouration to body spots, with largest spots near base of fin, followed by 3–4 rows of smaller spots distally; pectoral fin whitish; pelvic fin clear to white, with yellowish-orange pigment near base of fins; caudal fin with 3–5 rows of smaller spots of similar colouration to body spots.

Preserved. Head and body light brown. Dark bars below eye faint grey to brown, interspaces light brown; orange to yellow-orange or reddish-orange spots becoming light brown; dark brown bar connecting vertical bars under eye between spots faint with straight or slightly curved margins; caudal peduncle often with brown pigment forming two thin stripes; fins often clear, but in freshly collected specimens dorsal, anal and caudal fins with melanophores surrounding clear spots; spots on branchiostegal membranes in life not visible; pectoral-fin base with 2–3 light spots.

Variation. Two specimens from 38–50 m from Escape Reef are tentatively identified as this species. The specimens have a fairly large trench between the eyes, but colouration like T. okinawae . The male and female both lack a filamentous dorsal spine.

Adults have a fully scaled predorsal region, but juveniles below 13 mm SL often have few or no predorsal scales. The interorbital trench also increases in depth with growth, generally being absent in juveniles.

It is possible that more than one species is included here. Two slightly different colour forms are discernible. One form has thin dark bars below the eye ( Fig. 37 A), with the spots behind the eye on the preopercle connected to form a bar, or as two large spots. This form is found on reefs of the Timor Sea and Kendrew Reef off Western Australia and northern reefs of the Coral Sea. The second form has broader dark bars below the eye followed by a prominent light bar ( Fig. 37 B). This form is known from North West Cape, WA and Osprey Reef in the Coral Sea. One individual from the Great Barrier Reef has the spots separated, rather than a bar behind the eye ( Fig. 37 C). There is, however, considerable variation in specimens from Osprey Reef. In a majority of specimens the dark bands are narrower than the light interspaces, but in a few specimens the bands are as broad as the interspace.

About half of the specimens have the spots on the anterior opercle and preopercle separate, rather that connected to form a bar as found in specimens from Western Australia. In addition it is apparent that colouration changes considerably after preservation. The reddish-orange bar below the middle of the eye was narrow when freshly collected, but the pale area is now very broad after 34 years in preservation. The specimens from Osprey reef were collected almost 30 years ago and fresh colouration is unknown.

Distribution. (See Fig. 38 ). Trimma okinawae is found in Australia from Western Australia, islands of the Timor and Coral Seas, and rarely on the outer Great Barrier Reef. On the Great Barrier Reef it is normally found on reefs at the outer edge of the reef on the windward slopes below 20 m or in channels leading to the Coral Sea. The species is known from depths of 2– 35 m.

Etymology. Named after the Okinawa Islands of Japan, where the type specimens were collected.

Comparisons. For a comparison between this species and T. readerae sp. nov., see Comparisons section under that species, as well as for information regarding an analysis of the DNA barcode.

The head colouration of T. okinawae is similar to that of Trimma haima Winterbottom, 1984 , from the western Indian Ocean, where T. okinawae apparently does not occur. Trimma haima differs in lacking predorsal scales.

Discussion. The species reaches a maximum size of 28 mm SL (24 mm SL from Australia). Tentatively we apply the name Trimma okinawae to a species normally found on offshore reefs in Australia. As defined here the species normally lacks filamentous dorsal spines or has only a short second dorsal spine, has distinct vertical bands under the eye, a fully scaled predorsal and other features listed in the diagnosis above. The species from Australia matches colouration of Japanese material as shown by Hayashi & Shiratori (2003) and Senou et al. (2004), showing distinct bands under the eye and a slightly filamentous second dorsal spine. However, it appears from photos of fresh material from Japan that more than one species has bands below the eye. One form has the spots on the top of the head fused to form transverse bands across the nape ( Hayashi & Shiratori, 2003, #044), and the predorsal scales are reduced, with no scales on the midline anteriorly. The second form has a fully scaled nape and numerous spots on the nape, and we regard this as being Trimma okinawae .

This species has been reported to have a haremic polygynous mating system, with at least some individuals capable of bidirectional sex change ( Sunobe & Nakazono, 1990).

Figures

FIGURE 37. Trimma okinawae. A: Shark Bay, WA, WAM P. 26671 - 005 (B) Northwest Cape, WAM P. 25367 – 017, (C) Raine Id, GBR, AMS I. 20757 - 082. Photos: B. Hutchins (A); G. Allen (B); D. Hoese (C).

FIGURE 38. Distribution map for Trimma okinawae (solid stars).