Trimma nomurai Suzuki & Senou, 2007

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 : 64-66

Trimma nomurai Suzuki & Senou, 2007

Lilac Pygmygoby

Figs. 34–36 , Pl. 3 A

Trimma nomurai Suzuki & Senou, 2007:180 (Ie-jima Id, Okinawa Group, Ryukyu Ids, Japan); Allen & Erdmann, 2012:943 (Bali and West Papua to Japan).

Trimma sp. 14: Suzuki, 2004:116 (Okinawa).

Trimma sp. 3: Kuiter & Tonozuka, 2004:704 (x 2, Indonesia).

Australian material. Queensland: North Reef, 4 miles E. of AMS I.24489-006, 2(11–17), 23°09'S, 151°58'E, sledge, 64 m, 14 Dec., 1977, W. Ponder et al. Western Australia: Glomar Shoal: NTM S.10821-010, 2(10–20), 19°30'S, 116°47'E, 80 m, 19 Sept., 1982. NMV A.29732-001, (18.5), 12°25' 57"S to 12°26' 04"E, 123°35'52"E to 123°35'52"E, 111 m.

Diagnosis. A species of Trimma with 5–6 scales in the predorsal midline; well developed (deeper than wide) interorbital and postorbital trenches; an elongated second dorsal spine, which may reach to the anterior one-third of the caudal peduncle; 8–9 dorsal and anal fin rays; 18–19 pectoral-fin rays with about 7 rays branched in the approximate middle of the fin; a fifth pelvic-fin ray with two dichotomous branches (four tips) and which is 70–95% the length of the fourth ray; a pupil-diameter dark spot below the origin of the first dorsal fin (surrounded by a lighter area in life), four yellow stripes in the second dorsal fin and about six horizontal yellow stripes in the caudal fin, and, at least in adults, the whole opercle covered by a single, very large and thin cycloid scale.

Description. The description is based on the five Australian specimens, which were collected by sledge or trawl, and are not in very good condition (especially the two smaller examples). Dorsal fins VI + I 8, second spine of first dorsal fin elongated, reaching posteriorly to anterior one-third of caudal peduncle in largest specimen when adpressed, first fin ray unbranched, all other rays branched; anal fin I 8, first ray branched or unbranched, other rays branched; pectoral fin usually 18–19, five dorsal and seven ventral rays unbranched with seven branched rays in between (20 mm SL specimen only); pelvic fin I 5, first four rays with two sequential branches, fifth ray branched twice dichotomously and about 90–100% length of fourth ray in Australian material (as low as 72% in holotype); basal membrane about 30% length of fifth ray (but may be incomplete); no fraenum. Lateral scales 22; predorsal scales 6; transverse scales 6 (all based only on two larger specimens); scales cycloid anterior to lines between the pelvic- and ventral pectoral-fin base, and dorsal pectoral-fin base and base of fifth dorsal spine dorsally; scales ctenoid posterior to these lines; anterior extent of first predorsal scale approximately in line with posterior margin of pupil; opercle of largest specimen with a single, very large, deciduous, cycloid scale covering most of opercle (bilateral), a scale pocket present bilaterally in second largest specimen, neither scale nor scale pocket discernible in two smaller specimens); two vertical rows of three scales on pectoral-fin base (largest specimen only). Upper jaw with an outer row of 4–6 evenly spaced, curved, enlarged canines, continuing round jaw to mid-point, then decreasing in size to distal tip of premaxilla, numerous irregular rows of small conical teeth, innermost row very slightly enlarged, tapering to a single inner row at tip of premaxilla. Lower jaw teeth with outer row of four (each side) spaced, curved, enlarged canines, continuing round jaw to bend of dentary; several irregular rows of small conical teeth, innermost row enlarged (twice size of others), decreasing in size and number of rows to a single row posteriorly. Tongue truncately or sharply rounded, about two-thirds pupil diameter in width. Gill opening extending anteroventrally to below anterior third of pupil; outer gill rakers on first arch 3 + 11–12 (mean = 2 + 11.5, n = 2). Anterior nares opening at tip of thin tube about one-third pupil diameter in height, posterior nares a small pore on a slightly raised tube, nasal sac slightly elevated, nasal apparatus on anterior two-thirds of snout. Bony interorbital one-quarter pupil-diameter in width, interorbital and postorbital trenches well developed (deeper than wide), epaxialis musculature reaching anteriorly to above posterior margin of pupil at posterior margin of trenches. No specimens were available for vertebral type examination, but it is probably Type B.

Colour pattern. Freshly collected. Not recorded for Australian specimens. Following based mainly on original description by Suzuki & Senou (2007:181). Ground colour of head and body translucent pale lilac. Snout and jaws pale yellow, cheek greyish white and nape and opercular apparatus light yellowish brown. Iris yellow orange. Large rounded dark brown blotch (slightly larger than diameter of pupil) present just above midlateral septum between pectoral-fin base and bases of first three dorsal fin spines, broadly encircled by yellowish white. A large, oblique purplish-white blotch present on base of pectoral fin. Three yellow stripes (one just below dorsum, one along midlateral septum and third, which is intermittent, just lateral to ventral profile) start below posterior part of first dorsal fin and continue onto caudal fin. Median fins pale lavender, first dorsal fin with 3 yellow stripes, second dorsal fin with four yellow stripes, with distal part of both fins hyaline. In addition to continuation of yellow body stripes onto caudal fin, two (dorsal half) or one (ventral half) more yellow stripes, and outer tips of fin tipped with yellow. Anal fin with basal and submarginal yellow stripes and longitudinal series of four yellow blotches medially. Pectoral and pelvic fins hyaline, with yellow tinge on posterior part of latter fin.

Live (Pl 3 A, a juvenile from Palau). Head and body translucent with whitish cheek, well developed red bar, pupil diameter in width dorsally, tapering to about half that width ventrally, present on nape and passing down vertical limb of preopercle, dark spot between pectoral fin and the dorsal consists of rounded, pupil-width group of melanophores, surrounded by bright rounded spot which continues ventrally just behind pectoral-fin base and more vaguely dorsally to bases of anterior dorsal fin spines. Series of yellow-brown, oblique bars, oriented anterodorsally and apparently internal, arise from ventral midline to end at midlateral septum, separated by somewhat wider translucent interspaces. First bar just anterior to anus, second from mid-base of anal fin, third from just posterior to end of anal fin, fourth at mid-peduncle, and fifth from bases of procurrent fin rays. Colour pattern of caudal fin essentially as described for adults, other median fins translucent with diffuse streaks of yellow, and paired fins are hyaline.

Preserved. Straw yellow with dark, pupil-diameter rounded spot below bases of first three dorsal spines, anterior margin in line with base of first spine ( Fig. 35 ). Spot slightly more anteriorly situated in juvenile, with only posterior half below first dorsal fin base.

Etymology. Named for a Mr Tomoyuki Nomura, who collected the holotype.

Distribution. From Japan to north-west and eastern Australia, New Caledonia, and with underwater photographs from Bali, Indonesia and Palau ( Fig. 34 ).

Comparisons. All our specimens have the fifth pelvic ray branched twice dichotomously. In their original description, Suzuki & Senou state (:181) " fifth ray deformed (with 5 sequential branch points and 6 terminal tips)". We confess that we have never seen a species in this genus with more than four tips (two dichotomous branches) in the fifth ray other than T. mendelssohni , and re-examination of the holotype by one of us (DFH) revealed that the fifth pelvic ray is unbranched in this specimen (KPM-NI 4109). Although the fifth ray on one side is thickened near the tip, neither ray is branched. These rays in the holotype are also partially fused basally to the fourth rays on both sides, and we surmise that it is possible that the branching pattern described by Suzuki & Senou included the total number of independent branch tips for the two rays combined. A re-examination of the right pelvic fin of the paratype (NSMT-P 73058, left fin now broken) by Suzuki found that the fifth ray has two dichotomous branches (for a total of four ray tips), in typical fashion for those members of the genus with two dichotomous branch points ( Fig. 36 ). The authors also stated in the original description of the species that the opercle was scaleless. A reexamination of the holotype by Dr. Senou found that a single very large scale like that described above is present on both sides, but the scale is apparently absent from the 16.0 mm SL paratype (Suzuki, in litt.).

The only other species of the genus with a large black spot between the pectoral-fin base and the first dorsal fin is T. tauroculum Winterbottom & Zur, 2007 . This species has 17–18 (vs. 19) pectoral-fin rays, fifth pelvic ray branched once (vs. twice), no scales in the predorsal midline (vs. 5–6), no scales on the opercle (vs. one very large scale – at least in adults), 3–5 (vs. 8–10) rows of scales in the preventral midline, a shallow interorbital trough and a slight postorbital furrow (vs. both deep trenches), and rounded or hexagonal dark spots (vs. none) on the nape (see Winterbottom & Zur, 2007, for details).

No specimens were available for genetic analysis.

Discussion. This species is probably more widely distributed in the Western Pacific than current records indicate. Photographs of live specimens suggest that it is found in an unusual habitat for Trimma , with coarse sand and macrophytic green algae, although Allen & Erdmann (2012:943) record it from rubble bottoms in 20– 30 m.

Figures

FIGURE 34. Distribution map for Trimma necopinum (solid circles with white stars) and T. nomurai (solid squares with white circles).

FIGURE 35. Trimma nomouri, 19.2 mm SL male holotype (preserved), KPM-NI 4109, Ie-Jima Id, Okinawa. Photo by T. Suzuki.

FIGURE 36. Trimma nomurai, 16.0 mm SL female paratype, Ie-jima Id, Okinawa, 5 th pelvic ray branching, branch points denoted by arrows. Photo by T. Suzuki.