Trimma zurae, Winterbottom, Richard, Erdmann, Mark V. & Dita Cahyani, N. K., 2014

Winterbottom, Richard, Erdmann, Mark V. & Dita Cahyani, N. K., 2014, Three new species of Trimma (Pisces; Gobioidei) from Indonesia, Zootaxa 3838 (3), pp. 367-384 : 379-383

Trimma zurae n. sp.

( Figures 7–10 )

Suggested common name: Marg’s pygmy goby.

Material examined. Two lots, 6 specimens (12.8–22.6 mm SL). All material from Indonesia, North Sulawesi, west of Manado at Poopoh, (01° 24.897' N, 124° 37.757' E).

Holotype. ROM 94019, 22.6 mm SL female, 70 m, clove oil. 5 Sept., 2012, M. V. Erdmann.

Paratypes. MZB.22094, 2 (12.8–15.2), under sponge and rock bommie, 65 m, clove oil, 23 Sept., 2013, M. V. Erdmann. ROM 94886, 2 (17.4–18.3), collected with MZB.22094. USNM 427490, 1(13.3), collected with MZB.22094.

Non-type Material. MB0612501, (1), collected with MZB.22094, tissue specimen.

Diagnosis. Trimma zurae has 8–9 scales in the predorsal midline, usually a single row of cycloid scales along the upper border of the opercle, no cheek scales, 11 anterior transverse scales and 9 posterior transverse scales, no elongate dorsal spines, the second and third longest reaching posteriorly only to between dorsal interspace and the base of the second dorsal fin spine, 9 dorsal and 8 anal fin rays, the middle rays of the pectoral fin branched, a fifth pelvic fin ray which branches once dichotomously and is 65–76% the length of the fourth ray, and the basal membrane connecting the inner margins of the fifth pelvic fins rays is less than 20% the length of the fifth ray. The eye-diameter sized black ocellated round spot covering the first to fifth spines of the first dorsal fin is distinctive, as are the pupil diameter sized orange spots on the nape, opercle and posterodorsal part of the cheek.

Description. Dorsal fins VI + I 9, the second and third spines longest, reaching posteriorly only to between dorsal interspace and base of second dorsal fin spine when adpressed, rays all branched except posterior element of last ray, last ray reaching posteriorly 63– 79 % of distance from its base to first dorsal procurrent ray; anal fin I 8, all but posterior element of posteriormost ray usually branched (first ray unbranched in two); posteriormost ray 52– 72 % of distance from its base to first ventral procurrent ray; pectoral fin 17– 18, 3 and 2– 4 unbranched

dorsal and ventral rays respectively, middle 11 –13 rays branched, fin reaching posteriorly to a vertical line above bases of anal spine to second fin ray; pelvic fin I 5, no frenum, basal membrane reduced and 12 –18% length of fifth ray, first four rays with 1–2 sequential branch points, fifth ray branched once dichotomously and 66– 69 –76% length of fourth, fourth ray reaching posteriorly to between bases of anal rays 3– 4 –5. Lateral scales 23; anterior transverse scales 11; posterior transverse scales 9; predorsal scales 7– 9; no scales on cheek; opercle with 1 row of 2– 3 usually cycloid scales (scales mostly missing); pectoral base with 3 vertical rows of scales with 5 cycloid scales in posterior row; 6– 9 cycloid prepelvic scales (in midline anterior to basal membrane); 12 circumpeduncular scales; body scales ctenoid except for cycloid scales on anterior belly midline; and on, beneath and just posterior to pectoral fin base; body scales extending anteriorly to just behind eye. Gill opening extending anteroventrally to a vertical below posterior margin of pupil. Teeth not examined in detail, but appear to be typical of other Trimma . Cephalic sensory papillae ( Fig. 7 ) row counts given in Table 1 . Tongue truncate and bilobed, with rounded edges. Gill rakers on first arch 3– 5 + 13– 15 = 17– 20. Anterior nasal opening a short tube extending out over upper lip, posterior nasal opening a pore with a raised rim, both protruding from slightly raised oval sac confined to anterior half of snout. Bony interorbital 29– 30 –36% pupil width, with a broad moderately developed U-shaped interorbital furrow and a slight postorbital crease. No ridge of tissue (or dermal crest) extending anterior to first dorsal spine. Epaxialis extending anteriorly to above a vertical with posterior margin of orbit. Vertebral transition not examined, but predicted to be Type B (see Winterbottom, 2003, Fig. 14, inset, and Winterbottom & Zur, 2007, Fig. 3 B).

Colour pattern (live and freshly collected). Holotype, a 22.5 mm SL female ( Fig. 8 A): background colour of body pinkish-orange, somewhat lighter beneath dorsal fins; head and nape much lighter. Scale pockets may be lightly outlined with darker pink (especially dorsally). Snout with vermiculations of yellow and orange dorsally. A row of four yellow spots rimmed with orange around eye from below pupil to the two o’clock position, decreasing slightly in size from dorsal to ventral. Another line of five similar spots from the vertical limb of the preopercle upwards over the middle of the opercle to the top of the nape. A mixture of spots and lines of orange and yellow on dorsal interorbital and nape. Base of pectoral fin whitish (iridocytes) with scattered diffuse pinkish lines. First dorsal fin with an eye-diameter sized rounded black spot rimmed with a quarter- to a third- pupil width white halo (faint between bases of spines 3 to 5), rest of fin a mix of red, yellow and orange; base of first dorsal spine with a small, triangular black spot. Second dorsal fin with reddish rays, large iridocytes thickly scattered in fin membrane along with scattered small yellow spots (especially proximally), with an anterior reddish-black spot about half-way up spine. Anal fin similar, but with a faint yellow suffusion over distal half of fin (and no dark ocellate spot). Caudal fin with essentially same colour pattern, but the rows of yellow spots more regularly organized, and tinged with green. Pelvic fin rays whitish; those of pectoral fin pink-red with hyaline membranes. Iris yellowish, with four faint blue-grey spots surrounded by diffuse reddish-orange margins. An 18.3 mm SL female ( Fig. 8 B, ROM 94886) similar, but background colour a darker orange-red, vermiculations on snout less obvious, membranes of first dorsal fin distally outlined with black, a row of elongate yellow spots in second dorsal just distal to a basal dark stripe containing iridocytes, anal fin with a similar yellow stripe in membranes just distal to base of fin, iris orange-yellow, with four thin radiating purple lines. In life ( Fig. 9 ), body translucent pink, orange spots on nape separated by narrow light coloured lines, and similar lines forming vermiculations in interorbital region.

Colour pattern in alcohol ( Fig. 10 ): Background colour pale straw-yellow, all traces or red, orange, yellow and pink absent, spots on head and nape represented by clear areas. Head and body with numerous brown chromatophores, especially on upper lip, snout, dorsal portion of nape, and below dorsal fins where they tend to concentrate along scale margins. Black spot in first dorsal fin remains obvious, membranes immediately around it mostly clear of pigment cells, but with some brown chromatophores, especially along distal margin. Yellow spots in second dorsal fin now devoid of pigment cells, remainder of fin with scattered, at times dense, brown chromatophores. Anal fin similar. Caudal fin membranes with brown chromatophores. Membranes of pectoral fin hyaline, those of pelvic fin with some brown chromatophores. Iris uniform black.

Comparisons. Trimma zurae belongs to a group of nine previously described species which all have a scaled predorsal midline, no cheek scales, a scaled opercle, and at least the middle rays of the pectoral fin branched ( Winterbottom, 2006). Within this group, only Trimma caesiura Jordan & Seale, 1906, T. fraena Winterbottom, 1984 , and T. milta Winterbottom, 2002 , lack an elongate second spine in the first dorsal fin (vs. present). The first two of these species have 8 dorsal fin rays (vs. 9). Trimma milta has an unbranched fifth pelvic fin ray and only 7 anterior transverse scale rows (vs. branched and 11, respectively). Of the remaining species, T. mendelssohni ( Goren, 1978) has multiple branches in the fifth pelvic fin ray, and T. nomourai Suzuki & Senou, 2007 has two branches (for a total of four tips) versus a single branch point and two tips in T. zurae and the remaining species. Trimma lantana Winterbottom & Villa, 2003 , has deep, vertically sided trenches in the interorbital and postorbital regions of the head (vs. moderate trough and a slight crease respectively in T. zurae ). Trimma cheni Winterbottom, 2011 , and T. okinawae (Aoyagi, 1949) have a moderately elongate second dorsal spine that extends to about the middle of the second dorsal fin when adpressed (vs. not reaching beyond the base of the second dorsal fin spine). Trimma papayum Winterbottom, 2011 and T. irinae Winterbottom, 2014 have a greatly elongate second dorsal spine, reaching to the middle or beyond the second dorsal fin (vs. to or anterior to, the spine of the second dorsal fin). In addition, T. irinae has a distinctive dark spot on the branchiostegal membrane below the vertical limb of the preopercle (vs. absent). Trimma papayum also has two black spots basally in the first dorsal fin (vs. one small dark spot at the base of the first dorsal spine and a second, very much larger spot covering much of the area between the first and fifth dorsal spines).

Distribution. Trimma zurae is currently known only from off Poopoh, which lies just west of Manado in North Sulawesi, Indonesia, at depths of 65– 70 m.

Etymology. The species is named in honour of Margaret Zur, who has, for several decades, curated both the ROM and borrowed material of Trimma for RW’s research program, as well as taking and compiling reams of data on the specimens, plotting distributions, summarising results, and a myriad other tasks. Her work has been indispensable in keeping the Trimma project viable. This species has been informally referred to as Trimma RW sp. 104.

Discussion. As with the above described T. meranyx , T. zurae is another apparent example of a "twilight zone" species restricted to deeper reefs in the 65–70 m depth range. Given our extensive deep reef collections around eastern Indonesia, it is intriguing that this species has only been collected from this single locality in North Sulawesi. It seems likely this may be due to the very unusual microhabitat in which it was collected (which we have not previously encountered), which consisted of a very gradual reef slope to 70 m depth, exposed to strong upwelling from the nearby very deep (> 1000 m) waters surrounding it. The specimens were all collected sheltering beneath the large barrel sponges that dominated the reefscape.

Sequences for the mitochondrial gene CO1 have been deposited in GenBank under Accession Number KJ624417 .

Figures

FIGURE 3. Left lateral views of caudal peduncle pigmentation of preserved specimens of T. meranyx. A: 18.7 mm SL female holotype, ROM 94170. B: 17.8 mm SL female paratype, ROM 94721. Lembeh Strait, North Sulawesi. Photos by R. Winterbottom.

FIGURE 7. Trimma zurae, cephalic sensory papillae of a 17.4 female paratype, ROM 94886. A: Left lateral view of head. B: Dorsal view of head. Photos by R. Winterbottom.

FIGURE 8. Freshly collected specimens of T. zurae. A: Left lateral view of 22.5 mm SL female holotype, ROM 94019. B: Left lateral view of 18.3 mm SL female paratype, ROM 94886. Both images reversed. Photos by M. V. Erdmann.

FIGURE 9. Live specimen of T. zurae, off Poopoh, North Sulawesi. Photo by M. V. Erdmann.

FIGURE 10. Trimma zurae, 17.4 female paratype, ROM 94886, lateral view of preserved colour pattern of head and anterior body (right side reversed). Photo by R. Winterbottom.