Trimma capostriatum ( Goren, 1981 )

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 : 21-25

Trimma capostriatum ( Goren, 1981)

Spotted Redlined Pygmygoby

Figs. 8 B, 9–10, Pl. 1 E

Zonogobius capostriata Goren, 1981:94 ( New Caledonia).

Trimma striata: Randall et al., 1997:408 (Great Barrier Reef) ; Randall, 2005:553 (in part, New Caledonia, but not figure); Hoese & Larson, 2006: 1690 (in part, Great Barrier Reef).

Trimma striatum: Kuiter, 1996:361 ( Australia, but not figure).

Material. Holotype. MNHN 1980–1072, (19.5), Canala Bay, New Caledonia. Paratypes MNHN 980-660, 4(17.7–19.7), New Caledonia.

Australian material. Queensland: Ashmore Reef: AMS I.33715-040 78(9–28); Yonge Reef: AMS I.18740- 0 80, 22(9–24), 9–12 m; AMS I.20784-019, 10(17–26), 1–15 m; AMS I.20784-203, (21), 1–15 m; McGillivray Reef: AMS I.18805-003, 23(9–23), 11–15 m; Lizard Id: AMS I.18739-078, 11(8–26), 3–10 m; AMS I.18755-110, 13(9–24), 4–8 m; AMS I.19108-087, 48(9–29), 1–11 m; AMS I.20730-005, 3(23–26), 20–22 m; AMS I.20783- 0 0 7, 22(8–24), 2–4 m; AMS I.20994-006, 5(8–24), 2–7 m; AMS I.21529-005, 3(9–22), 8–15 m; AMS I.21539- 0 14, 33(14–23), 2–8 m; AMS I.21539-073, 3(19–25), 2–8 m; AMS I.22731-008, 23(17–27), 3–15 m; AMS I.35887-004, 3(18–25), 10–18 m; AMS I.20765-029, 18(20–27), 5 m; BMNH 1983.3.25:931–932, 2(23–24); NTM S.11447-019, (26); NTM S.11448-007, 7(21–26); Escape Reef: AMS I.22575-047, 4(17–20), 7–9 m; AMS I.22579-064, 6(19–21), 4 m; AMS I.22581-032, 60(17–24), 10–14 m; AMS I.22586-057, 8(20–24), 2–6 m; AMS I.22633-062, 30(17–26), 2–11 m; AMS I.22639-021, 7(20–28), 9 m; Swain Reefs: QM I.33411, (15), 3– 5 m.

Other material. Indonesia, Papua: Raja Ampat Ids: WAM P.33024-006, 3(13–19), 8–12 m; Pulau Lemon, Manokwari: WAM P.33039-004, 2(16–17), 5– 20 m. New Caledonia: BMNH 2009.4.1.52–54, 3(21–22), 6– 8 m. Palau: Helen Reef: ROM 84493, (19), 2– 8 m. Papua New Guinea: Port Moresby: NTM S.12231-004, 3(17–24), 6 m; NTM S.12232-002, (20), 9 m; NTM S.12237-001, (9), 6 m; NTM S.12564-001, (18), 22 m. Manus Id: WAM P.27827-044, (16), 7– 9 m. New Britain, Awaiama Bay: WAM P.31363-016, 2(21–22), 10– 15 m. New Britain, Kimbe Bay: WAM P.31152-019, 13(7.9–20), 7– 8 m. New Britain, Rabaul: AMS I.17503-015, (20); ROM 92269 (19); ROM 92310, 4(10–15). Solomon Ids: Florida Id: AMS I.17492-017, (19), 2– 20 m. Santa Cruz Id: AMS I.39008-072, 6(14–19), 10 m; AMS I.39031-075, (20), 28 m; AMS I.39034-022, (14). Hopel Id: NTM S.12710- 0 0 2, 2(23–24), 6 m. Vanuatu: Efate: AMS I.18434-005, 2(21–21). Vanua Lava, Banks Ids: AMS I.37920-043, (18), 13 m. Ureparapara Id: AMS I.37929-051, 12(9–16), 1–11.4 m.

Diagnosis. A species of Trimma with a deep trough in the bony interorbital region about half pupil-diameter in width; a shallow trough behind the eye along the upper half of the posterodorsal margin of the eye; predorsal midline naked, sides of nape scaled to just behind the eye; cheek and opercle scaleless; pelvic fins connected by a basal membrane reaching to the tips of fifth ray, forming an indented plate; central 4–11 pectoral rays branched; head with 5–6 light stripes (orange to red in life) and dark blue interspaces, body light with distinct scattered oval or round spots (yellowish-orange, orange or reddish in life). Snout mostly darkly pigmented without distinct stripes in preserved material, but with orange stripes in life; upper lip largely dark, except posteriorly, usually with orange stripes from the eye obscured by dark pigment on the jaws; lower lip uniformly dark; lower surface of the head with a black curved stripe ( Fig. 8 B) and with a median black bar connecting to the lower lip; branchiostegal membranes predominantly light, except for the stripe and the inner margin of the membranes.

Description. The description is primarily based on specimens from the Great Barrier Reef.

Dorsal fin VI + I 9 (rarely I 8 or I 10 in 7.8% of individuals, mean = I 9.0, n = 195), second spine longest, reaching to behind base of seventh segmented dorsal-fin ray to about middle of caudal peduncle when adpressed, third spine sometimes elongated into a short filament; first segmented ray of dorsal fin branched or unbranched in adult (unbranched in about 60% of adults), usually unbranched in specimens below 15 mm SL, anterior element of last ray usually unbranched (in 90% of adults); anal fin I 8 (rarely I 7 or I 9, in 5.2% of individuals, mean = I 8.0, n = 145), first ray usually unbranched, anterior element of last ray branched; pectoral-fin rays usually 17 or 18 (in 95 % of individuals), 16 in 1% of individuals, 19 in 4% of individuals; mean = 17.7, n = 195), reaching just posterior to a vertical in line between anal spine and third segmented anal ray; branching of pectoral rays variable, increasing significantly with size (p <0.05), usually upper 4–8 pectoral rays unbranched (up to 11 in juveniles below 15 mm SL), usually central 6–8 rays (rarely up to 11) branched; lower 4–7 rays unbranched; tips of fifth ray of pelvic fins connected by basal membrane, forming an indented plate; fifth ray about three-fourths length of fourth ray, ray thin and branched dichotomously two or three times (4–8 terminal tips); other rays thicker and branched sequentially, fourth ray with 4–5 terminal tips, third usually with 3–4 terminal tips and first and second rays with 2 terminal tips; pelvic fin reaching posteriorly to just before anus in juveniles (below 15 mm SL) to about third segmented ray of anal fin in larger adults; pelvic fraenum absent, full basal membrane present, but often torn; segmented caudal rays 16 (in 1), 17 (in 142); branched caudal rays 6/5 (96), 6/6 (16), 7/6 (2). Lateral scales usually 22–25, 22(2), 23(24), 24(89), 25(18), mean = 23.9, n = 133; transverse scales 7(39), 8(33), 9(3), mean = 7.5, n = 75; scales on pectoralfin base, breast, anterior 1–2 rows on sides of nape and anteriormost 3–5 scales on midline of belly cycloid, remaining scales ctenoid; a single small embedded median scale between bases of pelvic fins, covering part of basal membrane; cheek and operculum naked; sides of nape scaled anteriorly almost to eye (less than half scale diameter from eye), scales extending anteriorly in line from side of first dorsal origin downward to near posterodorsal margin of eye; scales below second dorsal fin smaller than other scales on side; pectoral-fin base with 9–13 oval cycloid scales, arranged irregularly in about 4–5 rows horizontally and 1–4 rows vertically (1 dorsally and 4 ventrally); usually second row with 1–2 scales slightly expanded vertically; prepelvic area with 6–7 rows of cycloid scales, not extending forward onto isthmus before posterior preopercular margin or onto sides of isthmus. Head moderately compressed, eyes dorsolateral; nape crest low from first dorsal origin to posterior opercular margin; teeth in lower jaw: an enlarged outer row of curved, enlarged, canines spaced about twice width of each tooth anteriorly on dentary, followed by 3–4 inner rows of smaller canines tapering to 2 rows posteriorly, an innermost row of slightly enlarged teeth (shorter than teeth in outer row, but longer than teeth in mid-rows); outer row of teeth in upper jaw enlarged, curved and very wide-set, covering anterior half of premaxilla, with 3–5 small irregular inner rows of teeth anteriorly, tapering laterally to 2 rows, anteriormost teeth in inner row slightly enlarged and directed posteriorly; tongue tip triangular to truncate, with central point; gill opening extending anteroventrally to below posterior margin of eye to posterior end of pupil; gill rakers on first arch 3–5 (rarely 5) + 14–17 = 17–21 (rarely 17 or 21, mean = 19.9, based on 37 specimens from the Great Barrier Reef); anterior nares at end of slender elongate tube just above upper lip; posterior nares with a raised rim, 1 naris diameter from anterior and 1.5–2 naris diameter from eye; nasal sac elevated. Interorbital trough shallow, reaching just behind interorbital papillae above middle of eye, a very short, shallow trench along or posterodorsal margin of eye, bony interorbital narrow, width about one third or slightly less of pupil diameter; jaws form an angle of 60–75° with body axis; horizontal line from tip of upper jaw passing through lower margin of pupil; nape crest low from first dorsal origin to above posterior quarter of operculum. Posterior abdominal/anterior caudal vertebral pattern is Type B.

Colour pattern. Live and freshly collected. From slides of freshly collected specimen from Lizard Island, Yonge Reef and Escape Reef, Great Barrier Reef ( Fig. 9 ), and underwater photos from Lizard Island (Pl. 1 E). Head with narrow reddish orange stripes (depth about half of charcoal blue interspaces ventrally and about equal to interspaces dorsally); dark interspace forming stripe on midline from first dorsal origin forward to posterior interorbital space or to just behind the posterior margin of interorbital trench, and not continuing as a distinct stripe between eyes or on snout (although there may be dark pigment in midline of the snout); uppermost light stripe extending from dorsal margin of eye to below first dorsal origin; second upper light stripe extending from posterodorsal margin of eye to below first dorsal fin; third light stripe from just above middle of eye, arching along dorsal margin of preopercle and opercle, ending just above pectoral-fin base; fourth stripe beginning along middle of upper lip arching upward and continuing along lower iris extending posteriorly onto upper pectoral base; fifth stripe beginning at posterior tip of jaws, but usually interrupted by dark pigment on jaws, extending horizontally along cheek on to pectoral-fin base, just below middle; lower surface of head with some orange pigment (not fully visible from slides, see preserved colouration); a short stripe from anterodorsal margin of eye crossing upper lip, but not lower lip, sometimes obscured by dark pigment; top of snout dark; body with an overall charcoal grey colouration, varying from dark (similar to interspaces on head) to a lighter grey; approximately 5 rows of round yellowish-orange, orange or reddish round and irregularly shaped oval spots; spots spaced longitudinally by at least 1 scale row. Pectoral and pelvic fins largely translucent, often with a yellowish or orange tinge. First dorsal fin with a narrow yellow to orange stripe near base (much narrower than head stripes), basal part of fin grey to dusky, distal two thirds of fin translucent to faintly grey. Second dorsal fin with a narrow yellow to orange stripe basally, similar to stripe on first dorsal fin, sometimes stripe broken into a series of spots centered on fin rays; above yellow or orange stripe a series of yellow or orange spots paralleling lower stripe anteriorly, but becoming irregular posteriorly; remainder of fin dusky to grey, darker below lower yellow or orange stripe. Anal fin yellow to orange, with distal margin of fin pale grey to bluish-grey. Caudal fin with yellow to orange pigment concentrated along fin rays, with membranes grey.

Preserved. Pattern of colouration generally similar to fresh colouration, with red and orange becoming light brown. A sixth light stripe extending from chin to pelvic-fin origin (not visible from slides, but probably reddishorange as in other stripes in life). Reddish-orange stripes becoming light brown and interspaces dark grey to black. Median dark stripe (interspace) from dorsal origin sometimes faintly discernible between eyes, but not extending onto snout. Upper stripe from anterior margin of eye present in specimens below 15 mm, but obscured by dark pigment in larger specimens; middle and lower stripes only narrowly cross upper lip, but not lower lip. Lower lip uniformly dark grey to black; usually with a distinct dark stripe extending from lower operculum and curving to meet stripe from other side just behind chin; a dark stripe connecting these bars with lower lip; inner margin of branchiostegal membranes dark, rest of membranes largely pale. Body light brown, with dense concentration of melanophores, becoming sparse posteriorly; reddish-orange round spots in freshly collected material becoming pale, without melanophores. Fins dusky, with reddish-orange stripes and spots without melanophores. Inner face of subopercle with dark pigment, outer face without melanophores. A dark stripe from pelvic-fin base forward to chin, extending on to inner margins of branchiostegal membranes as mentioned above.

Etymology. Not given. Presumably from the Latin “caput” (a head, end or point) and “ striatus ” (striped) in reference to the alternating red and charcoal-blue stripes on the head.

Distribution. Trimma capostriatum is known only from the south-west Pacific from the Great Barrier Reef, Australia, New Caledonia, Vanuatu, the Solomons, the Bismark Archipelago, northern and southern New Guinea and Helen Reef, Palau ( Fig. 10 ). It is common on middle and outer reefs on the Great Barrier Reef in depths of 1– 22 m. It is also known from Swains Reefs in the Coral Sea, but is not know from the Timor Sea.

Comparisons. Trimma capostriatum is most similar in head colouration and scale and fin-ray counts to Trimma striatum . The species differ primarily in body and chin colouration. They differ on average in pectoral ray counts (p <0.01), with T. capostriatum usually having 18 rays (mean 17.7), and T. striatum having 17 rays (17.1). Trimma capostriatum has round or oval light spots (yellow to orange in life) in longitudinal rows on the body. Each spot is centred on a single scale, but separated by one or more scales from other spots. In Trimma striatum the body is uniformly coloured. Frequently each scale has a thin, vertically elongate area lighter than the rest of the scale. The chin colouration is also distinctive in the two species ( Fig. 8 ). In Trimma capostriatum , there is a dark longitudinal stripe just behind the chin, connecting to the dark lower lip. In Trimma striatum , the lower lip is largely pale, followed posteriorly by a curved stripe crossing the midline, followed posteriorly by a stripe crossing the lower surface of the head behind the chin and without any dark connecting stripe (left-hand arrows in Fig. 8 ). In addition the branchiostegal membranes are normally dark, but pigment may intensify near inner margins in Trimma striatum , while in T. capostriatum the branchiostegal membranes are dark only along the inner margin (right-hand arrows).

The two species are largely allopatric, but do overlap in western New Guinea and Palau ( Fig. 10 —we have included the distribution of T. striatum here for the sake of completeness because the two species are easily confused, and both occur in Australian waters). Both species are sometimes found in a single sample (e.g. Raja Ampat Islands and Helen Reef in Palau). In Australia, Trimma capostriatum is only known from the Great Barrier Reef in eastern Australia, while Trimma striatum is found only on reefs in the Timor Sea off Western Australia.

Trimma capostriatum from the Great Barrier Reef and Rabaul, New Britain (n = 11) differ in their CO1 genome by 9.3% from six specimens of T. striatum from Palau and Raja Ampat, supporting the validity of these two species ( Winterbottom et al., 2014).

Discussion. In the larger samples from Lizard Island and Escape Reef sex ratios are approximately equal, but males average 1–3 mm more in length (p <0.001). Males reach a larger size, with the largest male being 29 mm SL from Lizard Island and the largest female 21.4 mm SL from Escape Reef. Outside of Australia the largest specimen examined was a 23 mm SL male from the Solomon Islands. The first segmented dorsal ray is typically unbranched, except in one sample from Lizard Island, where 40% of the individuals have the ray branched. These specimens are all larger than most specimens from other localities (20–24 mm SL), and the branching may be due to their larger size. No morphological or colour differences were noted between sexes.

Figures

FIGURE 8. Ventral view of the heads of A: Trimma striatum (20.0 mm SL male, ROM 83138) and B: T. capostriatum (19.2 mm SL male, ROM 84493), Helen Reef, Palau. See text for arrows. Photos by R. Winterbottom.

FIGURE 9. Trimma capostriatum, 23 mm SL, AMS I. 20784 - 203, Yonge Reef, Queensland. Photo by D. F. Hoese.

FIGURE 10. Distribution map for Trimma capostriatum (solid inverted triangles) and T. striatum (open inverted triangles).