Trimma kitrinum, Winterbottom, Richard & Hoese, Douglass F., 2015

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 : 40-42

Trimma kitrinum sp. nov.

Citron Pygmygoby Figs. 18–20

No published names pertain to this species.

Material. All the type material is from the Fiji Islands.

Holotype. ROM 45285, 25.2 mm SL female, Great Astrolabe Reef, eastern side of offshore reef about level of Dravuni Id (178° 33'42"E, 18° 44'51" S), 10–15 m, 29 Mar. 1983, Winterbottom et al.

Paratypes. AMS I.18354-061, 5(22.2–24.5), Viti Levu, Suva Harbour, Bird Id, 6 m, 9 Jul, 1974, B. Russell et al. ROM 45281, 2(15.1–21.1), Ngau Id, outer reef at eastern point (18°04'20"S, 179°22'40"E), 3– 9 m. 13 Mar. 1983, A. Emery et al. ROM 45284, 3(12.3–26.4), Great Astrolabe Reef, outer reef halfway between Usborn Pass and Herald Pass (178°33'42"E, 18 44'51" S), 10– 15 m. 29 Mar. 1983, Winterbottom et al. ROM 45286, 5(12.5–24.7), Viti Levu, Suva Harbour, Rattail Pass, right at tip of entrance on West Side (18°08'39"S, 178°23'21"E), 6–10 m, 14 Apr., 1983, Winterbottom et al. ROM 1419CS, (24.9), collected with ROM 45286, specimen cleared and stained. USNM 236724, 2(22.0–26.8), Kandavu Id, Dawson Reef, backside of barrier reef (19°04'S, 178°02'E), 0–13.7 m. 12 May, 1982, Springer et al. USNM 313339, (18.5), Lau Group, Matuku Id, outside channel (10°09'38"S, 179°45'23"E), 20–23 m, 24 Apr., 1982, Springer et al.

The following non-type material was also examined:

Australian Material. Queensland: Lihou Reef: WAM P.29641–013, (22), Juliette Cay (17° 21'S, 151° 33'E), 20–23 m, 14 Nov., 1987, G. R. Allen. Osprey Reef: AMS I.25107–058, 5(21.6–23.0), W. end, drop-off (13° 56'S, 146° 34'E), 10–25 m, 6 Nov, 1984, AMSRV Sunbird party.

Other Material. American Samoa: AMS I. 21998-001, 3(15.7–24.4), Pago Pago, Utelei, (14°17'S, 170°40'E), 20 m, 1976, R. Wass et al. DMWS-1, (21.2), Pago Pago, Utelei, (14°17'S, 170°40'E), 29 Sep. 1975. [ DMWS = Dept. of Marine and Wildlife Services, American Samoa]. DMWS-2, (21.1), Pago Pago, Utelei, (14°17'S, 170°40'E), 29 Sep. 1975. Indonesia: BPBM 18516 (12.9) Moluccas Id, Ambon Id, Latuhalay, S. coast, (3°46'30"S, 128°06'05"E), 36.5 m. 21 Jan. 1975, Randall et al. Loyalty Ids: USNM 321803 (23.0), Loyalty Id, Ouvea Atoll, Bagaat Id, (20°37'18"S, 166°16'08"E), 15–21.5 m. 16 Nov. 1991, J. Williams et al. Micronesia: Enewetok Atoll: BPBM unreg., (26.7), (11°30'N, 162°20'E), 3.5–27.5 m. Jan/ Feb. 1972, J. Randall et al, Guam: BPBM uncat., 2(16.3–22.2), Cocos Id. (20°37'N, 144°44'E) 29– 37 m. 28 May, 1968, Randall et al. Tonga: USNM 341449, 5(10.1–22.3), Vava'u Group, Luamoko Id., (18°40'55"S, 174°06'09"E), 21–31 m, 15 Nov. 1993, Williams et al.

Diagnosis. A species of the Trimma tevegae group with a brownish body and bright yellow caudal fin, with no dark marking on the posterior part of the caudal peduncle ( Fig. 19 ), 8 dorsal and anal fin rays, 13–14 unbranched pectoral-fin rays, usually 20–22 total gill rakers on the outer side of the first gill arch, 3–4 papillae in a transverse row at the posterior interorbital position of row p, and 3–5 papillae in a transverse row at the anterior position of row p; this transverse row usually extends anterior and lateral to the anteriormost papilla in row r ( Fig. 20 ).

Description. Based on the holotype and 19 other specimens from Fiji. Dorsal fins VI + I 8, second spine longest and reaching to between base of second ray of D2 and middle of peduncle when adpressed, first ray of second dorsal fin branched, posterior margin of last ray to anterior third to mid-peduncle; anal fin I 8, first ray branched, last ray branched reaching posteriorly to anterior third to mid-peduncle; pectoral fin 13 –14 (mean = 13.7, n = 19), all rays unbranched, fin reaching posteriorly to a point above urogenital papilla to anal spine; pelvic fin I 5, first four rays with one sequential branch each, fifth ray unbranched and 50 –66% the length of fourth (mean = 53.9, n = 11), fourth ray reaching posteriorly to a point between bases of second to fifth anal ray; no fraenum; basal membrane vestigial (<5% length of fourth ray). Lateral scales 23 –24 (mean = 23.4, n = 18); transverse scales 7 –8 (mean = 7.4, n = 18); predorsal scales in somewhat irregular rows, 11– 12 –14 (mean = 12.8, n = 16); scales on cheek, opercle, pectoral-fin base, breast, anterior midline of belly and anterior predorsal cycloid, others ctenoid; cheek, opercle and pectoral-fin base scales often abraded off and missing, cheek with 3 rows, 1 –3 in upper row, 7– 8 in middle row and 1 –3 in lowermost row; opercle usually with 3, 4 and 1 scales in three horizontal rows; pectoralfin base with 3 vertical rows of 4–5 scales within each row, although anterior row may have fewer; scales anterior to pelvic-fin base 5–9 (mean = 6.1, n = 9, value for holotype not determinable). Upper jaw teeth with an outer row of evenly spaced, straight, conical teeth extending to distal premaxilla, about twice the size of the inner teeth, which consist primarily of a single complete row with a few extra teeth near symphysis. Lower jaw teeth with an outermost row of 3–5 outwardly-flaring, enlarged, curved canines, a row of slightly smaller, straighter canines which decrease in size posteriorly and end on coronoid process of dentary, and 1–2 irregular rows of small conical teeth near symphysis, reduced to a single row posteriorly. Tongue truncately rounded, often with a slight central point at tip. Gill opening extends anteroventrally to below mid-pupil; outer gill rakers on first gill arch 4 + 16–1 8 (mean = 17.3), total rakers 20– 22 (mean = 21.3, n = 15). Anterior nares in a short tube adjacent to upper lip, posterior opening a large pore with a rim; nasal sac slightly raised; nasal apparatus confined to anterior half of snout. Bony interorbital width 70– 80 –100% of pupil diameter in width, interorbital somewhat concave with a raised median ridge of soft tissue (forming a broad, gentle ‘W’ in cross section); epaxialis reaching anteriorly in dorsal midline to above anterior to middle of pupil. Posterior interorbital papillae usually in a transverse row of 3–4 papillae on each side, anterior interorbital papillae either single or two arranged transversely on either side, (both in row p of Sanzo 1911), anteriormost part of row p also in a transverse row of 3–5 papillae bilaterally. Row r usually of five papillae on snout in a longitudinal row, oriented on a slant from anteriomedial to posterolateral ( Fig. 20 ). Abdominal/caudal vertebral transition Type A, with enlarged haemal arches present on first three caudal vertebrae, and last pleural rib on tenth abdominal vertebra.

Colour pattern. Freshly collected. From two freshly collected adult females from Great Astrolabe Reef, Fiji ( Fig. 19 ). Background colour light yellow-brown, somewhat darker over abdomen, with scale pockets more intensely outlined with dark chromatophores, particularly along dorsum. End of caudal peduncle lighter, grading into bright yellow caudal fin with streaks of violet-red in some interradial membranes, especially basally. Head, especially cheek and opercular regions, suffused with red. Iris mostly dark with yellow flecks, but with clear inner ring of yellow around lens aperture. Pectoral-fin rays red, with elements of pelvic, anal and dorsal varying between dirty yellow, red or brown. Fin membranes hyaline except for half-pupil diameter high basal band of melanophores in second dorsal fin. Specimens from Tonga, Solomons and Samoa are somewhat darker overall than Fijian examples.

Preserved. Similar, but all yellow and red areas replaced by a light brown background colour.

Etymology. From the Greek ‘kitrinos’, meaning ‘citron-yellow’ or ‘of citron’, in allusion to the distinctive yellow caudal fin of the new species. The species has been informally referred to as RW sp. 27 and DFH sp. 27.

Distribution. Currently recorded from Ambon ( Indonesia), Osprey Reef on the Great Barrier Reef and certain island groups in the western Pacific north to Guam, south-east to Fiji and Samoa ( Fig. 18 ).

Comparisons. The new species belongs to the T. tevegae species complex, with a broad (> half pupil diameter in width) bony interorbital and Type A vertebral pattern. Within this complex, it differs from T. griffithsi Winterbottom 1984 , T. nasa , T. tevegae and T. xanthochrum Winterbottom 2011 in lacking a dark spot or blotch on the caudal peduncle. The whole body of Trimma fishelsoni Goren 1985 , T. gigantum Winterbottom & Zur 2007 , and T. taylori is yellow in life. The former two species have diffuse dark saddles over the dorsum, with 15–17 (vs.

13–14) pectoral-fin rays of which 6–11 are branched (vs. all unbranched), and T. gigantum has more predorsal scale (15–18 vs. 11–14). Trimma taylori has fewer predorsal scales (6–8 vs. 11–14), at least some pectoral-fin rays branched (vs. unbranched), cheek below the eye without scales (vs. 3 rows), and in having more dorsal and anal fin rays (10–11 and 9–10 respectively vs. 8 and 8). Trimma kitrinum may be distinguished from T. marinae Winterbottom, 2005a , in possessing a complete nasal sac (vs. an open pit), more predorsal scales (11–14 vs. 6–8), in the presence of three rows of cheek scales (vs. none), and in colouration (yellow-brown body and yellow caudal fin vs translucent body above, red below, and a thin red bar at the base of an essentially hyaline caudal fin).

No specimens were available for genetic analysis.

Figures

FIGURE 18. Map of the distributions of Trimma insularum (solid squares with white centers), T. kitrinum (solid inverted triangles) and T. lantana (solid circles with white star).

FIGURE 19. Trimma kitrinum, 25.2 mm SL female (holotype), ROM 45285, Great Astrolabe Reef, Fiji. Photo by R. Winterbottom.

FIGURE 20. Trimma kitrinum, 25.2 mm SL female (holotype), ROM 45285, dorsal view head, stained to show cutaneous papillae. Photo by R. Winterbottom.