Trimma preclarum, Richard Winterbottom, 2006

Richard Winterbottom, 2006, Two new species of the gobiid fish Trimma from the coral reefs of the western Pacific Ocean (Pisces; Perciformes; Gobioidei)., Zootaxa 1331, pp. 55-68 : 63-66

Trimma preclarum , n. sp.

(Figs. 4B, 5-7)

Trimma sp - Hayashi & Shiratori, 2003:44 (bottom right, image # 073), Saipan

Suggested common name: Exquisite pygmy goby

Material examined

A total of ten lots, 33 type specimens (8.7-20.3 mm SL) from Fiji and Palau.

Holotype: ROM 77556, 20.3 male, south of Shark City, west side of Koror, south of Ulong Pass, 07°71'03"N, 134°12'00"E, drop-off wall with a few small caves, coralline algae, antipatherians and numerous small hard corals, 30.5-42.7 m, R. Winterbottom, W. Holleman, B. Hubley and D. Winterbottom, 11 June 2004.

Paratypes: Fiji Islands: ROM 46012, 11(8.7-18.2), Great Astrolabe Reef, 200 yards south of Usborne Pass, 18°42'24"S, 178°30'15"S, on outside reef, 3.1 km northwest of Vanuakula, 20-23 m, R. Winterbottom and collaborators, 21 Mar 1983. ROM 46013, 1(19.2), North Astrolabe Reef, outer edge of reef on northwest side, just southwest of Beagle Pass, 3.5 km northwest of Solo Island, 18°37'06"S, 178°30'21"E, 12-21 m, R. Winterbottom and collaborators, 24 Mar 1983. ROM 46014, 2(15.8-18.8), Great Astrolabe Reef, eastern side of offshore reef, about level with Dravuni Is., 18°44'51"S, 178°33'42"E, 10-15 m, R. Winterbottom and collaborators, 29 Mar 1983. ROM 46015, 2(21.0-21.7), Great Astrolabe Reef, NW corner of Herald Pass on outer reef, 4.1 km NW of Yanu-Yanu-Sau I., 18°45'19"S, 178°28'19"E, 10-20 m, R. Winterbottom and collaborators, 2 Apr., 1983. ROM 46017, 1(19.0), Great Astrolabe Reef, Herald Pass on outer reef, 4.1 km NW of Yanu-Yanu-Sau I., 18°45'08"S, 178°28'26"E, 27 m, R. Winterbottom and collaborators, 4 Apr., 1983. Palau: AMS I.43880-001, 3(14.3-17.5), Koror, due west of the Eleven Islands, 7°11'08.1"N, 134°12'56.0"E, almost vertical outer reef slope of coral/limestone interspersed with coarse shelly sand, numerous hard corals, a thin-thallused Halimeda , some leather corals, 33.5-44.5 m, R. Winterbottom and collaborators, 23 Mar., 2006. ROM 76417, 8(15.6-18.7), Koror, just north of pass to west of Ulong I., outer reef, 07°71'02" N, 134°14'09"E, 18.3-30.5 m, R. Winterbottom and collaborators, 07 June 2004. ROM 79465, 4(16.2-19.2 mm), collected with the holotype. ROM 80020, 4(17.4-19.2) Kayangel Atoll, east coast, almost vertical outer reef drop-off with many sea-fans and few small caves, 08°05'31.1"N, 134°41'24.9"E, 23-33.5 m, R. Winterbottom and collaborators, 08 Apr. 2006.

Diagnosis

Trimma preclarum is characterized by the presence of predorsal scales, second and third dorsal-fin spines elongate, moderate interorbital and postorbital trenches, no opercular scales, and scales across the top half of the body outlined with pigment. The fifth pelvic fin ray is branched sequentially once or unbranched depending on the capture location. When alive T. preclarum has three yellow stripes extending along the body, two stripes in the dorsal and anal fins (one dark and one yellow) and a red or cerise iris with four large, irregularly-spaced yellow spots.

Description

The description is based on the holotype and up to 32 paratypes. Dorsal fins VI I 9 (n=22), second and third spine usually elongate, with second spine reaching as far as the sixth element of the second dorsal fin, rays are branched except the first and/or last fin-ray; anal fin I 8-9 (mean = 8.8, n=21); pectoral fin 17-19 (mean = 18, n=20) with 6-7-10 branched rays in the approximate centre of the fin, reaching posteriorly to a vertical line with the first few elements of the anal fin; pelvic fin I 5, no frenum, basal membrane no more than 10%, often vestigial, first four rays with one sequential branch, fifth ray unbranched (specimens from Fiji) or with one sequential branch (specimens from Palau) and 50-65% the length of the fourth, fourth ray reaching posteriorly to a vertical line with the second to fifth element of the anal fin. Lateral scales 22-23-24 (mean = 23.1, n=20), anterior transverse scales 7-8 (mean = 7.6, n=17), posterior transverse scales 6-7, (mean = 6.8, n=17); predorsal scales 6-9 (mean = 7.4, n=16); 3-7 rows of cycloid scales on breast, 6-11 cycloid scales on pectoral base, usually either in two rows of 3-4 scales or three rows of 2-4 scales, often a single additional scale at the dorsal margin of the patch; scales on the head extend to the postorbital trench, cheek and opercle scaleless. Gill opening extending anteroventrally to below the posterior margin of the pupil to mid pupil. Upper jaw with an outer row of widely spaced enlarged canines with two inner rows of small conical teeth. Lower jaw with an outer row of enlarged widely spaced canines across the front of the jaw, a middle row of small closely spaced canines and an inner row of widely spaced medium canines. The two inner rows of teeth on the lower jaw extend around the whole jaw as far as the coronoid process. Tongue round, or parenthesis shaped. Gill rakers on first arch 3-4 + 13-15 = 16-19, (mean =17.9, n=10). Anterior nasal opening a tube adjacent to the upper lip, posterior nasal opening a pore with a raised rim, both nasal openings on a raised oval sac confined to the anterior half of the snout. Bony interorbital 1/4-1/3 pupil width, with moderately developed interorbital and postorbital trenches (both wider than deep), cephalic sensory papillae as in Fig. 7 A -C.

Colour Pattern: (from slides of freshly collected specimens from Fiji and Palau, and underwater photographs of live specimens - Figs 5, 6). Freshly collected specimens have three long yellow stripes down the side of the body on a dirty white to grey, semitranslucent background. The uppermost stripe begins at the origin of the first dorsal fin and runs along the top of the body. The middle stripe follows the mid lateral septum and begins in the centre of the body, roughly in line with the middle elements of the first dorsal fin. The ventralmost stripe begins just anterior to the anus and runs along the ventral portion of the body. All three stripes extend onto the caudal fin. Scale patterns are outlined across the body with melanophores, and chromatophores are scattered throughout. The dorsal fins have two stripes, a dark, one-third to one-half pupil width basal stripe, followed immediately by a thinner one-quarter pupil width yellow stripe. The anal fin is similar but the yellow stripe is wider than the basal stripe (about one-half pupil width), and may be followed by another thin dark stripe at the distal end of the fin rays. The iris is red to cerise with four large, irregularly-spaced, semi-circular yellow spots at the two, five, seven and ten o’clock positions, and small white bands or bright blue spots are present across or on the dorsal margin of the eye. Yellow bars may extend from the three ventralmost yellow spots onto the snout and cheek. A fourth yellow bar curves around the anterior edge of the opercle to the bottom of the cheek. Additional yellow blotches may be present on the head, but no recurring pattern was found. Preserved: body straw yellow with chromatophores sprinkled on head and body, with heavier concentrations dorsally and on the anterior sections of the body. The scale pattern on the dorsal half of the body is outlined with melanophores, creating a complete diamond pattern (pattern may be obscured if concentration of brown chromatophores is very heavy). Chromatophores on the pectoral base and the dorsal half of the opercle evenly distributed, chromatophores on the cheek ‘patchy’, with light bars on the cheek sometimes present. The wide, dark basal stripe in both dorsal and anal fins is readily apparent, and is followed by a hyaline stripe. Distal portions of fins have a medium concentration of melanophores. Melanophores are present in the interradial membranes of the caudal fin, and sparsely present in the pelvic fins. The pectoral fins are hyaline. A distinct band of melanophores is present on the snout. The band crosses the snout, over each nasal sac and passes up from the outside of each nasal sac to the orbit. Melanophores also extend up the centre of the snout, between the eyes to the anterior of the interorbital trench (Fig. 7B). Specimens from Palau have a highly reflective silver iris which is surrounded by a black ring (this may be the result of capture and/or preservation methods), while specimens from Fiji have a simple black iris.

Affinities

See the discussion under T. anthrenum for the differences between that species, T. preclarum and T. milta .

Distribution

Trimma preclarum has been found at Fiji, Palau, Papua New Guinea, Solomon Is., and has been photographed underwater in Saipan.

Etymology

Named for the Latin word “preclarus”, meaning splendid or very beautiful, in reference to the wonderful colouration of the new species when alive, especially the multihued iris.

Trimma preclarum has been referred to informally as Trimma RW 26 .