Trimma readerae, Winterbottom, Richard & Hoese, Douglass F., 2015

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 : 75-78

Trimma readerae sp. nov.

Red-spotted Pygmygoby Figs. 42–43 ; Pl. 2 D, E

Trimma okinawae (non Aoyagi, 1949): Randall, 1990:408 (Great Barrier Reef, but photo is of BPBM 8012, from Enewetak); Hoese & Larson, 2006:1690 (in part Great Barrier Reef).

Trimma sp.: Hayashi & Shiratori, 2003:44 ( Japan).

Material. Holotype. AMS I.20784-020, 22.5 mm SL female, inner side of Yonge Reef, Queensland, (14°37'S, 145°38'E), 1 Dec., 1978, AMS party.

Paratypes. Outer Barrier Reef: AMS I.20774-113, 45(11–22), off Cape Melville (13°56'S 144°36'E), 0–8 m, 9 Feb. 1979, AMS party. Yonge Reef: AMS I.19456-076, 18(11–21) inner side of reef (14°35'S, 145°37'E), 5–15 m, 12 Nov. 1975, AMS Party; AMS I.20784-087, 13(16–22) taken with holotype; AMS I.25065-011, 5(13–20), channel between Yonge and Carter Reefs (14°35'S, 145°36'E), 9 m, 7 Feb. 1977, H. Larson and B. Goldman; ROM 39329, 2(19–23) inner side of reef (14°35'S, 145°36'E), 8–13 m, 18 Sept. 1981, R. Winterbottom. Lizard Id: QM I.39131, 11(17–21), North Point, (14°40'S, 145°27'E), 5–6 m, 30 Jan. 1975, D. Hoese et al., Escape Reef: AMS I.22578-064, 14(18–21), (15°49'S, 145°50'E), 6–10 m, 28 Oct. 1981 AMS party; AMS I.22621-037, 9(15–22), inner side of reef (15°49'S, 145°50'E), 5–8 m, 27 Nov. 1980, W. and J. Starck. One Tree Id: AMS I.15682-061, 8(20–24) outside of lagoon (23°30'S, 152°05'E), 30 m, 27 Nov. 1969, F.H. Talbot et al.

Non-type material. Queensland: Tijou Reef: AMS I.20956-021, 11(15–22), 3–12 m; AMS I.20779-149, 13(12–22). Outer Barrier Reef off Cape Melville: AMS I.20774-084, (19), 0–8 m; AMS I.20774-257, (11), 0–8 m, Yonge Reef: AMS I.18740-077, 12(7–20), 9–12 m; AMS I.19454-092, 2(17–18), 1–18 m; AMS I.19472-091, 28(9–21), 7– 15 m. McGillivray Reef: AMS I.19482-135, 23(9–25), 3– 25 m. Lizard Id: AMS I.19607-024, 2(14–16), 5–6 m; AMS I.21578-004, (22); AMS I.21894-011, (16). North Direction Id: AMS I.19442-079, 3(14–22), 12 m. Outer Barrier Reef off Townsville: AMS I.20965-015, 7(10–25), 10– 20 m. Escape Reef: AMS I.22573-036, 3(16–19), 14–17 m; AMS I.22574-031, 7(12–23), 3–6 m; AMS I.22579-079, 4(17–20), 1–4 m; AMS I.22582-052, 19(10–22), 14–17 m; AMS I.22583-039, 2(15–16), 29 m; AMS I.22584-029, (20); AMS I.22587-020, (18), 40 m; AMS I.22612- 0 32, 8(11–21), 20 m; AMS I.22616-047, 14(10–19), 5–18 m; AMS I.22619-042, 16(11–20), 19–22 m; AMS I.22634- 0 13, 7(9–20), 18 m. Western Australia: Cartier Id, Timor Sea: AMS I.26752-024, 7(19–22), reef front off N side 12 m. North West Cape: WAM P.26631-015, 19(16–26), N of Mangrove Bay, 12– 14 m.

Other material. Indonesia: N E side of Ambon Id about 2 km E of Sawa Telu: ex-USNM 210230, 3(11–21), 0– 8 m. Saparua: USNM 209963, 20(9–20 m), 4– 9 m. Marshall Ids: Eniwetok Atoll: AMS I.37693-014, 17(17–21); AMS I.37687-004, 5(13–20), 7 m; AMS I.37695-002, (14); AMS I.37709-007, 20(17–24), BPBM 29222, 2(13–16), 7 m. Kiribati: Abaiang Atoll: AMS I.18043-064, 6(12–21), 5– 8 m. Solomon Ids: Florida Id: AMS I.17497-016, 3(16–18), 2–5 m; Florida Id: AMS I.17500-028, 2(19–21), 20– 30 m. Savo Id: AMS I.17491- 0 39, 3(17–19), 10 m. Guadalcanal: AMS I.27020-003, (19), 32 m.

Photos. KPM-NR0034522, Malaysia; KPM-NR0052877, Borneo; KPM-NR0052878, Okinawa.

Diagnosis. A species of Trimma with a moderately deep interorbital trench in adults, a shallow groove behind the upper half of the eye in adults, largely disappearing below the papilla at the posterodorsal margin of the eye; predorsal almost completely covered with ctenoid scales, with 3–6 rows crossing the midline anteriorly to just behind the interorbital trench, anterior-most scale on the midline just behind a small naked patch posterior to the eyes, scale not larger than the second scale on the midline; opercle and preopercle naked; pectoral-fin base covered with 5–6 large cycloid scales, lowermost 3–4 scales smaller than upper two scales; prepelvic area with a small scale covering basal membrane between the two fins, followed anteriorly by a large scale between the bases of fins, and 3 rows of large cycloid scales anteriorly; central pectoral rays branched; pelvic fins widely separate, connected only at their bases, the distance between the bases of the fins about three–quarters to equal to the base of each pelvic fin; fifth pelvic ray usually unbranched, rarely with a single branch (2 terminal tips); fifth ray 60–80% the length of the fourth; second dorsal spine usually longest, elongated into a long filament in adult males, reaching to beyond the end of the second dorsal fin, females sometimes with a short filament reaching to above the anterior rays of the second dorsal fin; third spine sometimes a short filament; second dorsal usually I 9 and anal rays usually I 8; two distinct round red to reddish-orange spots below the eye; branchiostegal membranes with distinct bright reddish-orange spots; body with small yellow to red spots in 4–5 irregular rows anteriorly and three rows on the caudal peduncle.

Description. The description is based on specimens from the Timor Sea, Great Barrier Reef, Coral Sea and Solomon Islands. Dorsal fin usually VI + I 9 (I 8 or I 10 in 10% of individuals), mean = I 9.0, n = 60, second spine longest, often elongated into filament (reaching first segmented rays in juveniles and well beyond end of second dorsal fin in some large males, in some females first spine also filamentous and longest; first ray of second dorsal fin usually branched in specimens above 14 mm SL and unbranched in smaller specimens; anterior element of last ray branched; anal fin I 8 (rarely I 7 or I 9, in 6% of individuals), mean = I 8.0, n = 60, first ray usually branched, anterior element of last ray branched; pectoral-fin rays usually 18– 19, (Queensland mean = 18.1, n = 37, Western Australia mean = 18.5, n = 15, Solomon Islands mean = 17.8, n = 9), upper 5–8 rays unbranched, central 5–12 rays branched and lower 3–6 rays unbranched; pectoral fin reaching just posteriorly to a vertical in line from urogenital papilla to about second segmented ray of anal fin; pelvic fin I 5, fins widely separate with very low interradial connecting membrane, covered by a median scale, distance between bases of fins slightly less than base of each pelvic fin; first four rays with one sequential branch, fifth ray usually unbranched, 50–80% length of fourth ray, which reaches posteriorly to below point between first and third anal rays, segmented caudal rays usually 17; branched caudal rays usually 6 upper + 5 lower (rarely 6 + 6 in <3% of specimens); predorsal scales crossing midline 3– 6, anterior two scales on midline, posterior scales overlapping on midline and no scales on midline covering nuchal crest (Queensland mean 3.6; n = 19, Western Australia mean = 4.9, n = 14, mean Solomon Islands 5.3, n = 8); lateral scales 22–25, usually 23 or 24 (Queensland mean 23.8; n = 36, Western Australia mean = 23.9, n = 14, mean Solomon Islands 23.3, n = 8); transverse scale count 6–8, usually 7 (Queensland mean 7.1; n = 31, Western Australia mean = 7.0, n = 14, Solomon Islands mean 7.0, n = 8); preopercle and opercle scaleless; scales extending to edge of postorbital trench above posterior part eye; scales just below dorsal fin with small accessory scales; pectoral-fin base covered with 5–6 large cycloid scales, lowermost 3–4 scales smaller than other scales; prepelvic area fully scaled, with small scale covering basal membrane between fins, followed anteriorly by large scale between bases of fins and 3 rows of large of cycloid scales anteriorly. Nape crest low and indistinct, extending to just before dorsal origin and above posterior opercular margin. Teeth in lower jaw consist of enlarged outer row of curved, slightly enlarged wide-set 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 eye. Outer gill rakers on first arch elongate, almost equal to filament length at angle, 3–4 + 11–13 = 15–18 (mean = 16.3, n = 20). Anterior nares at end of narrow tube, just above upper lip, posterior nares small pore with raised rim about two nostril diameters from anterior nares and two nostril 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 below 18 mm SL.

Colour pattern. Freshly collected specimens from Great Barrier Reef (from slides of freshly collected specimens from Yonge Reef and Escape Reef, Queensland, Fig. 42 ). Head and body with numerous orange to yellow-orange or reddish-orange spots with interspaces grey to bluish grey, except ventrally on body where interspaces whitish. Short orange bar extending from anterior margin of eye below nostrils to upper lip and along dorsal margin of upper lip; followed by elongate orange spot or bar extending to just behind posterior end of jaws; two round orange spots below middle of eye; followed by similar sized spots near end of preopercle; upper preopercle with oval orange spot extending onto upper opercle, followed posteriorly by oval spots extending from upper part of opercle onto nape; pale orange vertically elongate spot ventrally on opercle; two large round reddish spots ventrally on branchiostegal membranes below opercle and preopercle, spot below opercle with thin dorsal projection onto posterior end of opercle; pectoral-fin base with two large round orange spots; nape with large orange spots, some connected across nape forming bars; orange to reddish-orange spots on body round anteriorly, but becoming smaller and vertically elongate posteriorly and ventrally, spots forming 3–5 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 grey, with orange pigment near base of fins; caudal fin with 4–6 rows of smaller spots of similar colouration to body spots; pectoralfin base with upper and lower orange to yellow-orange or reddish-orange spot, with central spot extending onto bases of pectoral-fin rays.

Live. (from two images from Great Barrier Reef, Pl 3 D and E): similar to above, but body somewhat translucent; white spot present on top of pectoral-fin base, better developed in light phase than in dark phase; iris red with some darker pigment near outer rim dorsally and ventrally.

Preserved. Head and body light brown, Grey interspaces dark grey to brown; orange to yellow-orange or reddish-orange spots becoming light brown; dark brown bar connecting vertical bars under eye between spots faint and sometimes absent, with margins of bands concave above and below indicating position of spots; 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 three light spots.

Etymology. Named for Sally Reader, of the Australian Museum, in appreciation of the many years she has spent painstakingly gathering, analyzing and documenting data on Trimma for DFH’s research program, some of which has been used in the present paper.

Distribution. Trimma readerae is known from mid to outer reefs on the Great Barrier Reef, and inshore reefs of Western Australia, but rarely from the Coral Sea and Timor Sea. It sometimes occurs with Trimma okinawae , which is typically more common on offshore reefs of the Coral and Timor seas. On the outer reefs Trimma readerae is usually found in back reef leeward areas. The apparent scarcity of the species north of Tijou Reef is probably an artefact relating to collecting effort. For example, samples from Raine Island and other reefs of the northern Great Barrier Reef were generally from the seaward face of the reef. The species is known from a wide range of depths from 3– 40 m. We tentatively include here, in what appears to represent a species complex, specimens and images from the Solomon Islands, Indonesia, Borneo, New Guinea, Japan and the Marshall Islands, based on the spotting pattern on the cheek. However, Winterbottom et al. (2014) noted 8 distinct forms (haplogroups) of what they identified as T. okinawae (see below), with all groups except 5 and 6 from Japan and Taiwan having spots under the eye. Specimens from Raja Ampat in Indonesia closely resemble Australian specimens in live colouration, but differ significantly genetically, suggesting multiple species. Consequently we restrict the type material to the Great Barrier Reef.

Comparisons. The species is most similar to the species treated here as Trimma okinawae (q.v.). It differs primarily in having light spots under the eye, rather than light vertical bars, and in having filamentous dorsal spines in males and frequently females. In addition, the spot posteriorly on the middle of the preopercle is much smaller than other spots on the head (versus subequal in size to, or continuous with, the spot above in Trimma okinawae ). The second dorsal spine is usually filamentous reaching to or beyond the middle of the second dorsal fin. In females the second spine is longest and sometimes filamentous, reaching to above the first few rays of the second dorsal fin. Trimma okinawae normally lacks filamentous dorsal spines, but also has the second dorsal spine longest. In other populations the spines is frequently filamentous. The pelvic fin varies considerably in length, but normally does not extend beyond the second segmented anal ray, versus fourth or fifth segmented ray in Trimma okinawae . Faded preserved specimens can be difficult to consistently separate.

Winterbottom et al. (2014) provided a DNA barcode analysis of 28 specimens provisionally identified as T. okinawae . They recovered eight haplogroups, all but one confined to a single geographic area, suggesting the possibility of multiple cryptic species. The two specimens from the Great Barrier Reef in their analysis (Group 8) were phenetically closest to three specimens from Raja Ampat, Indonesia plus one specimen from Rabaul, New Britain (Group 7), but separated from them by 7.1% of the CO1 base pairs. The other specimens were from Brunei, Fiji, Japan, New Caledonia, Taiwan and Thailand.

Discussion. The species reaches a maximum size of 28 mm SL.

Figures

FIGURE 42. Trimma readerae, 22.5 mm SL holotype, AMS I. 20784 - 020, Yonge Reef, Queensland. Photo by D. F. Hoese.

FIGURE 43. Distribution map for Trimma readerae (solid diamonds).