Trimma taylori Lobel, 1979

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 : 84-87

Trimma taylori Lobel, 1979

Yellow Pygmygoby

Figs. 47–48 , Pl. 3 H

Trimma taylori Lobel, 1979:3 (Oahu, Hawaii); Winterbottom, 1984:710 (Chagos Archipelago); Myers, 1989:243; Randall, 1996:163; Kuiter, 1998:209; Yano, 1998:25:26; Hayashi & Shiratori, 2003:38; Allen et al., 2004:331; Kuiter & Tonozuka, 2004:706; Senou et al., 2004:103 (x 3); Anderson, 2005:105; Randall, 2005:554 (photo from Solomon Ids); Bacchet et al., 2006:554; Allen & Erdmann, 2012:947 (Red Sea to Hawaii and Society Ids); Motomura et al., 2013:337 (x 2, Japan). Trimma okinawae (non Aoyagi, 1949): Kuiter, 1992:263.

Trimma sp. 12: Kuiter & Tonozuka, 2004:706.

Material. Numerous specimens, from the Red Sea and western Indian Ocean to Hawaii, with photographic records east to the Society Islands. The great extent of the holdings we have examined has prompted us to simply list the general locality with the acronym of the institution in which they are housed for all but the Australian material.

Australia material. Queensland: Ashmore Reef: AMS I.33717-085, 11(9–16), 1–32 m; AMS I.33720-060, 23(10–12), 2–32 m; AMS I.33730-041, 33(8–21), 21– 32 m. Off Cape Melville: AMS I.20774-115, (18), 8 m. Escape Reef: AMS I.22580-020, 3(18–19), 37 m; AMS I.22629-009, 6(17–23), 50–60 m; AMS I.20577-009, 2(25–26), 30 m. Flora Reef: WAM P. 29643-014, (23), 20– 30 m. Herald Cays: WAM P. 28537-026, 6(14–24), 15– 25 m. One Tree Id: AMS I.18279-001, (26), 25– 30m. Raine Id: AMS I.20775-117, 89(11–22), 20 m. Tijou Reef: AMS I.20779-148, 220(11–20), 25 m; AMS I.20956-023, 4(17–20), 3–12m; AMS I.20956-023, 4(17–20), 10–20 m; AMS I.20779-148, 100(11–20), 0–25 m; ROM 40545 and ROM 816CS, 26(11–20), 25 m. Yonge Reef: AMS I.20784-024, (19), 1– 15 m. Western Australia: Ashmore Reef: WAM P. 29047-037, 2(15–17), 20–25 m; Rowley Shoals: WAM P. 28024-024, (15), 35– 40 m. Christmas Id: AMS I.20436-012, 6(19–22), 25– 35 m. AMS I.20441-014, (18), 40– 42 m. ROM 66969, (10), 20– 30 m. WAM P. 26084-003, (18), 40–45 m; WAM P. 26097-013, 5(16–19), 35–40 m; WAM P. 28991-012, 32(11–23), 20– 30 m. Cocos (Keeling) Ids: ANSP.

Other material. Chagos Archipelago: ROM. Fiji: Great Astrolabe Reef: ROM, USNM. Lau Group: USNM.

Hawaii: Oahu, BPBM (holotype, paratypes), AMS, BMNH, CAS, MCZ, ROM, USNM (paratypes). Indonesia: Moluccas: BPBM, ROM, USNM, WAM. Batuata Id, CAS, ROM. Kepulauan Lucipara: ROM. Mojo Id: CAS. Sulawesi: ROM. Raja Ampat: ROM. Malaysia: Sabah: USNM. Marshalls: Kwajelein: BPBM. Micronesia: Ponape: USNM. Palau: Main Ids: BPBM, CAS, ROM. Helen Reef: ROM. Papua New Guinea: Hermit Ids: USNM, WAM. New Britain: WAM, Trobriand Ids: USNM. Philippines: Apo Id: USNM. Balicasag Id: USNM. Cacares Reef: USNM. Cebu, south tip: ROM, USNM. Mactan Id: ROM, USNM. Negros, Bais: ROM, USNM. Negros, south tip: USNM. Palawan: LICCP. Pamilikan Id: USNM. Panay Id: LICCP. Pescador Id: USNM. Siquijor Id: ROM, USNM. Sumilon Id: ROM. Solomons: Bouganville Reef: BPBM. Florida Ids: AMS. Guadalcanal: ROM. Red Sea: Saudi Arabia: ANSP, ROM. Sudan: ROM. Taiwan: southern part: BPBM. Tonga: Vava'u: ROM. Vanuatu: Espiritu Santo: AMS.

Diagnosis. A species of Trimma with a bony interorbital ≥ pupil diameter; midline of the predorsal region fully scaled in adults; 9–11 branched pectoral-fin rays; a branched fifth pelvic-fin ray that is about 74% the length of the fourth ray; usually 3 upper gill rakers; a truncate to wedge-shaped caudal fin (dorsal rays longer than ventral); first five haemal arches expanded; and lacking a dark caudal spot (colour yellow to pink in life).

Description. The description is based on 20 specimens from Tijou Reef, Great Barrier Reef (AMS I.20779–148 and ROM 40545 plus two cleared and stained specimens, ROM 816CS), 16.3–19.0 mm SL, with additional information from specimens from Chagos ( Winterbottom, 1984), Philippines, Solomons and Great Barrier. Dorsal fin VI + I 9–10 (mean = 10.0, n = 22), second spine reaching between base of fourth dorsal-fin ray to anterior part of caudal, almost to end of peduncle in very large (> 22 mm) males from other localities, third spine shorter than second, but may be elongated and reach to base of third fin ray in males, spine elongation usually more pronounced in males than in females, all rays branched except posterior element of last ray (although occasionally anterior element of this last ray is also unbranched), last ray reaching posteriorly to between 50–75% length of peduncle (almost to anterior procurrent-fin rays in large males from other localities); anal fin I 10 (once 8, in specimen with abnormal anal fin in mid-region, in which rays displaced), all rays except posterior element of last ray branched, last ray reaching to between 0.5–0.8 length of peduncle; pectoral fin 13–14 (mean = 13.9, n = 22), uppermost 2 and lowermost 1–3 rays unbranched (mean = 1.8, n = 22) with 9–11 (usually 10) branched rays in between; pelvic fin I 5, fifth ray branched once or twice dichotomously (some specimens with lateral half of first branch remaining single and medial branch dividing dichotomously second time to form 3 terminal tips), 64–89% (mean =73.6, n = 15) length of fourth ray, which reaches posteriorly to bases of second to fourth elements of anal fin, first four rays branching sequentially 2–4 times (usually 3), no fraenum, basal membrane 100% length of fifth ray (but frequently torn); caudal fin usually wedge-shaped, with longest ventral ray about 85% length of longest dorsal ray. Lateral scales 23; transverse scales 7–8 (mean = 7.2, n = 20); predorsal scales 9–11 (mean = 10.2, n = 18); breast and midline of belly with cycloid scales, 6–7 scales in midline of breast (mean = 6.1, n = 10); 3–4 vertical rows of cycloid scales on pectoral-fin base, if 3, middle scale larger than others; no scales detected on cheek or opercle. Teeth in outer row of both jaws of evenly spaced, enlarged curved canines (not extending beyond bend in dentary), inner row of lower jaw teeth similar, other teeth small and conical, in irregular rows. Tongue pointed, its maximum width equal to about half-pupil diameter. Gill opening extends anteroventrally to below midpupil; outer gill rakers on first arch 3–4 + 13–15 (usually 3–4 + 14), total 17–19 (mean = 17.5, n = 19). Anterior nares in short tube, posterior opening pore-like with raised rim, nasal sac scarcely elevated and nasal apparatus confined to anterior half of snout. Bony interorbital 80–100% (mean = 97.1, n = 20) pupil diameter; shallowly concave with median fleshy ridge forming broad, gentle, rounded W in cross section; epaxialis extending anteriorly to above middle of pupil.

Vertebral transition Type A, but with haemal arches of first five (rather than two) caudal vertebrae expanded to form a tapering conical space which accommodates posterior extension of swimbladder; pleural ribs present on first four caudal vertebrae.

Colour pattern. Live/freshly collected. Based on colour slides of living specimens from the Great Barrier Reef, Hawaii and Indonesia (Pl. 3 H), and freshly collected specimens from the Chagos Archipelago, Christmas Island, the Philippines, Indonesia and Fiji. Live Hawaiian specimen (= type locality) translucent yellow, a row of elongate, pupil diameter yellow spots at base of first dorsal fin, three such rows in second dorsal fin, caudal and pelvics yellow, anal yellow with smudges of melanophores, especially proximally, iris yellow near pupil, with anterodorsal and posteroventral smudges of reddish brown margined with purplish blue. Live Indonesian specimens with dorsal half of body translucent except for scale-pockets outlined with red, ventral half of body and head translucent red to red-orange, (median fins not in focus), iris yellow with red blotches margined with purplish-blue dorsally, ventrally, anteriorly and posteriorly, latter two blotches smaller than former two. One specimen yellowish rather than red, with small light purple spots on the abdomen. Freshly collected specimens from Chagos off-white with a reddish-pink suffusion, body with longitudinal rows of yellow spots one-third pupil diameter at bases of scale pockets, scale pockets outlined with pink (especially dorsally), all fins except pectorals densely speckled with melanophores and iridocytes, with 2–4 longitudinal rows of yellow spots one-third pupil diameter in dorsal and anal fins, caudal with about five irregular such rows. Christmas Island, Philippine and Great Barrier Reef ( Fig. 47 ) specimens similar, but body yellow rather than reddish-pink. Fiji specimen appears to have faded prior to being photographed, and is pinkish-white with orange suffusion on head.

Preserved. Straw-yellow with occasional scales on dorsal half of body margined with melanophores and/or chromatophores, and melanophores usually visible in dorsal and anal fin membranes.

Etymology. Named for Dr Leighton R. Taylor, a former Director of the Waikiki Aquarium (1975–1986), and Professor of Zoology at the University of Hawaii at Manoa, Honolulu.

Distribution. As the species is currently conceived, it is one of the most widely distributed in the genus. It ranges from the southern half of the Red Sea and the Comores to Hawaii and the Society Islands, including the Great Barrier Reef and the off-shore reefs of Western Australia ( Fig. 48 ).

Comparisons. Trimma fishelsohni , T. gigantum , T. hoesei , T . kitrinum sp. nov. and T. marinae among the described species of Trimma possess a broad bony interorbital and lack a caudal spot. Trimma marinae appears to lack a caudal spot, although there are nearly always some dark chromatophores ventrally on the peduncle; this species differs from T. taylori in having eight dorsal- and anal-fin rays, and in having an open nasal pit without anterior and posterior narial openings. Trimma taylori differs from T. hoesei in possessing a wedge-shaped (vs. forked) caudal fin; first five caudal vertebrae with expanded haemal arches (vs. first only); predorsal fully scaled (vs. scaled half way to orbit); usually 14 pectoral-fin rays with the upper two rays unbranched (vs. usually 15 rays with upper three unbranched); usually three upper gill rakers on the lateral surface of the first gill arch (vs. four) and usually 14 (vs. 15) lower rakers; and body and median fins with yellow spots about one-third pupil diameter (vs. absent). In addition, the profile of the snout is sharper and more convex in T. hoesei than in T. taylori (cf figs. 19 and 25 in Winterbottom, 1984). Trimma fishelsoni and T. gigantum differ from T. taylori in possessing cheek scales (vs. absent) and in having fewer dorsal and anal fin rays (8–9 and 7–9 vs. 9–10 and 10 respectively). Trimma kitrinum may be immediately distinguished from T. taylori by the possession of eight dorsal- and anal-fin rays, and in having all pectoral-fin rays unbranched.

Winterbottom et al. (2014) analysed the CO1 gene from 20 specimens identified as T. taylori . They found three haplogroups. Group 1 (from Fiji, n = 2) differed from Group 2 ( New Caledonia = 1; Palau = 4, Raja Ampat, Indonesia = 1) by 2.4%. These two groups differed by a minimum of 17.6% from Group 3 (Hawaii = 4, Palau = 5 and Raja Ampat = 3). The latter includes specimens from the type locality (Hawaii). It is unknown which haplogroup (if any) the Australian specimens belong, as unfortunately no material is currently available for analysis. We provisionally use the name T. taylori for the Australian specimens pending the collection of tissue specimens for analysis.

Discussion. This species (if, in fact, all the specimens so identified here represent a single species) has the second widest distribution in the genus, from Hawaii and the Society Islands to the northern Red Sea. It should be noted that the two available specimens from the middle region of the Red Sea both have D VI + I 9, and further samples are necessary to determine whether the lower number of rays has any significance. Several underwater colour slides extend the range to the northern Red Sea. An in depth analysis of the various populations of this species has not been undertaken, and it remains possible or even probable that more than one species are masquerading under this name.

The species is found in depths of 8–55 m, but is usually found on drop-offs below 20 m. In eastern Australia it is known only from reefs on the outer edge of the Great Barrier Reef.

Figures

FIGURE 47. Trimma taylori, AMS I. 20775 - 117, Raine Id, Northern Queensland. Photo by D. F. Hoese.

FIGURE 48. Distribution map for Trimma taylori (solid pentagon) and T. xanthum (solid circles with white stars). A hollow square with an X in it indicates localities at which both species occur.