Trimma macrophthalmus ( Tomiyama, 1936 )

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 : 48-52

Trimma macrophthalmus ( Tomiyama, 1936)

Large-eye Pygmygoby

Figs. 24–25 , Pl. 2 C

Eviota macrophthalmus Tomiyama, 1936:47 (Hatizyô-zima, Idusiti-tô).

Trimma flammeum (non Smith 1959): Hayashi & Shiratori 2003:36, 40.

Trimma macrophthalma: Burgess et al., 1990:577 ; Kuiter, 1998:236; Yano, 1998:25; Myers, 1999:pl. 163; Allen et al., 2004:329; Senou et al., 2004:97 (x 2); Randall, 2005:553; Allen & Erdmann, 2012:941 (partim, Christmas Id, east to Fiji; East African record referable to T. flammeum ).

Trimma macrophthalmum: Motomura et al., 2013:336 , 337 ( Japan).

Trimma macrophthalmus: Kuiter & Tonozuka, 2004:704 (x 2); Kuiter & Debelius, 2006: 662.

Australian Material. Queensland: Portlock Reef: AMS I.33751, 12(9–15). Ashmore Reef: AMS I.33731–092, 29(10–19), 18 m. Boot Reef: AMS I.33747-035, 6(9–14), 30 m. Raine Island: AMS I.20757-083, 4(15–20), 0–20 m; AMS I.20775-060, (14), 0– 20 m. Tijou Reef: AMS I.20956-022 (14), 20 m. Carter Reef: AMS I.25065-014, 6(9–14), 9 m.; Yonge Reef: AMS I.18740-078 (18), 9–12 m; AMS I.25065 (10), 10 m. Osprey Reef: AMS I.25112- 0 43, 23(9–20), 1– 15 m. off Cape Melville: AMS I.20774-111, 8(11–19), 0– 8 m. Herald Cays, Coral Sea: WAM P.28537-002, 3(12–17), 15– 25 m. Holmes Reef, Coral Sea: AMS I.30465-115, (12). One Tree Island: AMS I.15682-062, 4(13–22), 29 m; LACM 33723-54, 2(22–24). Timor Sea, Western Australia: Ashmore Reef: NTM S.12318-067, 3(10–16), NTM S.12328-068, 9(9–17), 19–20 m; NTM S.12331-053, (15), 20– 21 m. Cartier Reef: NTM S.12883, (14), 13–14 m; NTM S.13427-029, 2(10–15), 25 m; NTM S.13420-055, 2(11–18), 6– 8 m.

Other material. Borneo: Darvel Bay: USNM 298749, (14). Christmas Id: AMS I.20430–015, (19); WAM P.26085–022, (18); WAM P.26098–011, (12); WAM P.26099–024, (19); WAM P.26110–017, 7(13–20); P.26122–007, 3(16–18); WAM P.28997–017, 39(8–15); WAM P.29010–014, 5(9–15). Cocos (Keeling) Ids: ANSP 134883, 2(16–18); WAM P.29915–025, (13); WAM P.29926–022, (15). Fiji: Bega Lagoon AMS I.18448–040, (11). Great Astrolabe Reef: ROM 46021, 2(12–15); ROM 46023, (15); ROM 46024, 61(9–18). Indonesia, Ambon: BPBM 4(15–19); USNM 210230, 17(11–18); USNM 245243, (14); USNM 264563, 3(11–14). Bali: NTM S.11203, 3(14–18). Banda Id: USNM 264915, 8(10–14). Buton Id: USNM 266269, 3(13–15). Ceram: USNM 209670, (14; Flores: AMS I.34501–060, 2(12–16); BPBM 2(16–16); ROM 70677, 2(15.8–16.1). Groote Banda: USNM 245212, 4(10–15). Haruku Id: USNM 264917, (16). Lucipara Ids: BPBM, 2(15–17). Naira Island: USNM 264569, 3(11–15). Namalau: USNM 264594, 16(9–16). Penyu Id: CAS 62535, 2(14–15). Raja Ampat Ids: ROM 84916, 5(8–16); ROM 84936, (14); ROM 85062, 2(10–14); ROM 85253, 17(8–15); ROM 85274, 5(9–13); ROM 85292, 6(10–17); ROM 85304, 13(9–14); ROM 85372, 2(16–17); ROM 87405, 5(16–21); ROM 87419, 2(12–15).

Roen Id: USNM 244200, 32(9–11); USNM 295288, (9). Saparua: USNM 209976, 4(10–16). Sulawesi: ROM 64644, 24(10.1–13.3); USNM 263457, 22(12–17). Tandjung Tala: USNM 209860, (15). Palau: Main Ids: ROM 80460, 48(8.3–15.9); ROM 80485, 28(7.7–15.1. South West Ids, Merir Id: ROM 83042, 34(8.2–15.6); ROM 83043, 93(8.3–17.5). Papua New Guinea: Bagabag Id: USNM 245258, (13). Hermit Ids: USNM 244119, 2(10–11); USNM 245261, (16); USNM 298798, (15). Madang: CAS 65402 (14); ROM 66967, 2(13.5–13.9); USNM 295399 (12). Manus Id: WAM P.27824-038 2(13–15); Massas Island: USNM 262626, (13); USNM 264704, (14). Ninigo Ids: USNM 244188, (13); USNM 298773, 4(14–16). Rabaul: ROM 92165 (8); WAM P.28178–011, 4(9–14). Trobriand Ids: USNM 298808, (15); USNM 295129, 10(9–11); USNM 298783, (13). Philippines: Batan Id: USNM 293351, (14). Caban Id: AMS I.21914-016, 5(12–18); AMS I.21918-033, 19(11–17). Cebu Island: ROM 49221, 4(9.7–14.6). Siquijor Id, Mindanao Sea: ROM 52982, (20); ROM 52984, (16). Puerto Galera, Mindoro: LACM 42491–76, (18). Sombrero Id: AMS I.21908-011, 11(12–16); AMS I.21915- 0 60, 45(10–17). Solomon Ids: Guadalcanal: AMS I.17485 (12); ROM 46046, 13(9–15); ROM 46050, 4(9–12); ROM 46054, 9(10–12). Taiwan: ROM 82472, 6(12.7–15.3); USNM 292982 (15). Vietnam: Nha Trang: ROM 73197, (12.6).

Diagnosis. A species of Trimma with a very narrow interorbital, a shallow groove before the middle of the eye, and no groove behind the eye; no scales in the predorsal midline, sides of nape scaled to a line extending from below a point between the first dorsal origin and the second dorsal spine, arching concavely to a point above and between the posterior opercular margin to the dorsal pectoral-fin insertion; cheek and operculum naked; nape crest low to above the posterior end of the operculum; pectoral fin with central rays branched (usually 8–12 branched rays, but varying from 5–15, increasing with size); pelvic fins form a plate, with the basal membrane connected to the tips of the fifth rays; fifth ray about 60–90% the length of the fourth ray and branched dichotomously (usually twice, with 4 terminal tips); fourth ray ends before the anus; first to fourth rays with two or three sequential branches and 3–4 terminal tips; second dorsal spine longest, often elongated into a short filament; second dorsal and anal fin-rays usually I 9; head with large rounded or oval (red in life) spots, pectoral-fin base with 3 grey to black spots; body with reddish orange spots along the margins of the scales.

Description. The description is based largely on specimens from the Great Barrier Reef. Dorsal fin VI + I 9 (rarely I 8 or I 10 in 4% of individuals, mean = I 9.0, n = 223), second spine longest often elongated into a short filament reaching to between bases of first to eighth segmented dorsal-fin rays when adpressed, first segmented ray of dorsal fin unbranched, anterior element of last element branched; anal fin I 9 (rarely I 8 or I 10, in 7% of individuals, mean = I 8.9, n = 223), first ray unbranched, anterior element of last ray branched; pectoral-fin rays usually 18 (in 71 % of individuals); 16 (in 1.5% of individuals), 17 in (17% of individuals), 19 (in 10% of individuals), mean = 17.9, n = 206, reaching just posterior to a vertical in line above and between anus and second segmented anal ray; upper 2–5 (usually 3–4) pectoral rays unbranched, central 5–16 (usually 8–12) branched, lower 2–7 rays unbranched; first four pelvic rays with 2 or 3 sequential branches and 3–4 terminal tips; fifth ray usually with two dichotomous branches (4 terminal tips), rarely with one or more small branches near tip of ray resulting in 5–7 terminal tips, 60–90% length of fourth ray, pelvic fin reaching posteriorly to below anal fin origin to about third segmented ray of anal fin in larger adults; fraenum absent, basal membrane present, usually connected to tip of fifth ray, but often torn; segmented caudal rays 16 (in 16), 17 (in 204); branched caudal rays 6/5 (22), 6/6 (54), 7/6 (7). Lateral scales 22–26, 22(9), 23(47), 24(45), 25(10), mean = 23.5, n = 112; transverse scale count usually 8, (rarely 9 in 10% of individuals), mean = 8.1, n = 86; scales on pectoral-fin base, breast, and sometimes anteriormost 1–2 scales on midline of belly cycloid, remaining scales ctenoid; a single median scale, easily lost, between bases of pelvic fins, covering part of pelvic membrane; head naked, scales extending anteriorly in arch above and between posterior opercular margin to dorsal pectoral-fin insertion upward and slightly forward to below a point between first and third dorsal spines, with scales not reaching midline; scales below posterior end of second dorsal fin normally without small accessory scales; pectoral-fin base with 9–11 medium sized scales of similar size, arranged in two vertical rows, scales easily lost and sometimes absent in juveniles below 11 mm SL; prepelvic areas covered with small scales in 5–7 rows, extending well forward onto isthmus. Head moderately compressed, eyes dorsolateral; teeth in lower jaw: an enlarged outer row of curved, enlarged, evenly spaced canines anteriorly on dentary, followed by two inner rows of similar, but smaller canines tapering to a single row posteriorly; outer row of teeth in upper jaw similar to those of lower jaw, covering anterior half of premaxilla, with two small irregular inner rows of teeth; tongue tip with rounded to slightly triangular anterior margin; gill opening extending anteroventrally to below pupil, usually near middle of pupil; gill rakers on first arch 2–4 (rarely 4) + 10–13 = 13–16 (mean = 14.9, n = 16); anterior nares at end of moderate tube just above upper lip; posterior nares with raised rim or almost tubular, one tube diameter from anterior and less than that diameter from eye; nasal sac slightly elevated. Interorbital trough shallow, reaching interorbital papillae above middle of eye, no posterior or posterodorsal trough, bony interorbital narrow, width about one third pupil diameter; jaws form an angle of 60–70 with body axis; horizontal line from upper margin of upper jaw passes through mideye; nape crest very low from first dorsal origin to posterior opercular margin, often not discernible. Abdominal/caudal vertebral transition Type B.

Colour pattern. Live individual from Great Barrier Reef (based on photo by A. Gonzalez-Cabello – Pl. 2 C). Head and body with dirty grey to reddish background. Head with series of yellowish-orange spots, slightly smaller than pupil diameter, ventral most spots on operculum darker than other spots; spots round to elliptical; spots continuing onto body in 3–5 longitudinal rows becoming less distinct behind second dorsal fin; spots on head and body separated by distance roughly equal to or slightly greater than spot diameter. Pectoral-fin base with 3 small (about 2/3 diameter of head spots) reddish orange spots, with dense melanin near center of spot. Dorsal fins with yellow to reddish-orange thin stripe (less than one-third pupil diameter) near base, rest of fins translucent grey, with darker pigment along leading edges of ray and spines; caudal fin dusky yellow, darker anteriorly. Pectoral fin translucent, with yellowish-orange tinge basally. Pelvic fin not visible in photo. Photos of live individual from Indonesia (by G. Allen and G. Barrall) are similar, but spots on the head and body are more reddish.

Freshly collected specimens (from slides of freshly collected specimen from the Philippines, Taiwan, Fiji and Palau, Fig. 24 ). Head and body with translucent to dark grey background. Head and body spots yellow, orange or reddish-orange. Cheek (excluding operculum) usually with five large spots and 2–3 smaller light spots. Ventrally on gill cover two dark brown to reddish brown spots extending onto branchiostegal membranes; pigmentation of spots similar to that of pectoral-fin base spots. Pectoral-fin base with three small (about 2/3 diameter of head spots) black or reddish black spots; anteriormost spot on anterior median portion of pectoral base, partly covered by operculum; posterior two spots form base of triangle on upper and lower posterior portion of pectoral base, sometimes with one smaller spot between the two posteriormost spots. Dorsal fins with yellowish orange to red thin stripe (less than one-third pupil diameter) near base, rest of fins translucent grey, with darker pigment along leading edges of rays and spines and sometimes with scattered small yellow spots along leading edge of rays; caudal fin dusky yellow to grey, darker anteriorly, often with 2–3 rows of yellow spots near base. Pectoral fin translucent, with a yellowish-orange to reddish tinge basally.

Preserved: background colour straw yellow with faint brown chromatophores. Spots (yellow, reddish or orange) in fresh material becoming pale without pigment; interspaces light brown to dusky. Three spots on base of pectoral fin small, usually with distinct dark brown to black pigment.

Etymology. Not given, but presumably derived from ‘macro’, large and the Greek noun ‘opthalmos’, meaning eye. The name was originally spelled as ‘macrophthalmus’, so we retain that spelling here because the second half of the specific name is a noun.

Distribution. Trimma macrophthalmus is known in Australia from reefs off Cape York, south to Yonge Reef and One Tree Island in southern Queensland and islands of the Coral Sea. It is probably widespread along the entire Great Barrier Reef, and is most common on the outer-reefs. It is found on Swains Reefs in the Coral Sea and in back reef areas on the outer barrier islands. It is also known from Ashmore and Cartier reefs in the Timor Sea. The species occurs in depths of 1 to 38 m, but is normally found below 10 m in Australia. Outside of Australia it ranges from Cocos (Keeling) Islands and Christmas Island in the Indian Ocean through Indonesia north to Japan and south to New Guinea and east to Fiji ( Fig. 25 ).

Variation. Approximately twice as many females as males were found. Of the specimens examined 137 were females and 74 males. The two sexes differed little in average size with males averaging 13.6 mm SL and females size 13.3 mm, and the size difference was not significant (p = 0.15).

Comparisons. In Australia the species is most likely to be confused with Trimma necopinum , which has similar fin-ray and scale counts and general reddish head and body colouration. See Comparison under that species.

The species is most similar overall to Trimma flammeum from the western Indian Ocean. Comparison of data for over 200 specimens of T. macrophthalmus with 70 Trimma flammeum showed no statistically significant differences in scale and fin-ray counts. The only distinguishing features are the spot pattern on the pectoral-fin base and size of spots on the head and body. In Trimma flammeum the three spots on the pectoral-fin base are in the same position as those in T. macrophthalmus , but the spots are red in life and fade to light areas in preservative. In T. macrophthalmus the spots are dusky to dark brown and fade to grey spots in preservative. However, in specimens from some areas, such as the Philippines and Ashmore Reef in the Timor Sea, the spots are variable in preserved material. In some of these samples the dark spots are visible in only about half of the specimens. When the dark spots are absent in Pacific material, they are absent on both sides of the fish. Rarely, in specimens below 11 mm SL, only one or two dark spots are visible. Consequently we cannot rule out the possibility that T. flammeum may extend to the Pacific and may be misidentified as T. macrophthalmus . In freshly collected specimens of Trimma flammeum , the light body spots are usually as large or larger than the interspaces, and the head spots are much larger than the interspaces. In T. macrophthalmus the body spots are smaller than the interspaces and most of the head spots are about equal to or slightly smaller than interspaces.

Fifteen specimens of T. macrophthalmus , from Palau (n = 6), Raja Ampat (n = 4) and Taiwan (n = 5), had a variance of 0.7% in their CO1 base pairs. They differed by a minimum of 9.0% of the CO1 genome from 27 specimens of T. flammeum from South Africa (n = 5), Madagascar (n = 2), Seychelles (n = 3) and the Andaman Islands (n = 17), which exhibited a within-group variance of 1.1% ( Winterbottom et al. 2014).

Discussion. The species is one of the smaller ones in the genus, and is generally less than 20 mm SL. The largest specimen is 22 mm SL from the southernmost locality known in Australia on One Tree Island, Queensland. The holotype ZUMT 30331 was not found by DFH in 1980 and was not found by W. Eschmeyer (in lit.) in 1997 and is apparently lost (I. Tomiyama pers. comm., 1980).

Figures

FIGURE 24. Trimma macrophthalmus, 14.8 mm SL female, Sonsorol Id, Palau, ROM 82983. Photo by R. Winterbottom.

FIGURE 25. Map of the distribution map for Trimma macrophthalmus (solid squares with white centers).