Trimma ukkriti, Winterbottom, 2021

Winterbottom, Richard, 2021, A new species of Trimma (Pisces: Gobiidae) from western Thailand, north-eastern Indian Ocean, Zootaxa 4915 (2), pp. 264-272 : 265-271

Trimma ukkriti new species

Ukkrit’s Pygmygoby

Figs. 1–4 .

Trimma okinawae (non Aoyagi 1949:173): Winterbottom et al. 2014:98 (DNA barcode analysis, in part, Thailand specimens)

Material examined. A total of 73 specimens (8 of which are tissues) from the seas around Phuket, Thailand (Andaman Sea, Malacca Strait). The samples were collected by Richard Winterbottom, Wouter Holleman, Randy Mooi, and Ukkrit Satapoomin.

Holotype: ROM 68764 (23.5), Ko Racha Yai, SE side, patch reef, 7.587222, 98.368611, very varied cor-als— Acropora , Porites , Pectinia , Pavona , Astreopora , Millepora , etc., visibility 10.5 m, 3.0– 6.1 m, rotenone, RW 93– 21, 19 Nov., 1993.

Paratypes: PMBC 11448, 11(14.9–26.0), Ko Dok Mai, west side, 30 m N and nearer shore than RW93-27, reef profile dropping away at average of 45°, some caves, 7.797222, 98.534167, some corals, lots of Diadema , whip corals, large siliceous sponges, visibility 10.5 m, 0–15.2 m, rotenone, RW 93–28, 24 Nov., 1993. ROM 68093, (25.5), Ko Aeo, NE side, base of fringing reef towards shore, 7.763055, 98.34, 50% live vs dead coral ( Acropora , Porites , Pectinia , Pavona ), very little algae, heavy siltation on rubble (mostly staghorn), visibility 4.5 m; 0–6.1m, rotenone, field # RW93–04, 10 Nov., 1993. ROM 68094, 5(10.8–24.6), Ko Racha Yai, S tip, steep (45°) wall of large boulders (up to 3 m diameter), 7.583333, 98.3625, little coral growth or algae, visibility 9 m, 15.2–21.3 m, rotenone, field # RW93–20, 19 Nov., 1993. ROM 68095, 6(10.3–25.9), Ko Hi, bay on S coast about middle of its length, base of fringing reef and adjacent sand/silt interface, 7.741667, 98.375833, 90% live coral, with encrusting Astreopora , Pavona , favids, Porites , Acropora , little algae, visibility 9 m; 6.1-10.1 m, rotenone, field # RW93–05, 11 Nov., 1993. ROM 68756, 2(22.8–23.8), Ko Lon, North side, outer fringing reef off sandy beach, from base of reef landward, 7.786111, 98.395833, 50 % live/dead coral ( Acropora , Pavona , Porites bommie), little algae, heavily silted, 0–9.1 m, rotenone, field # RW93–03, 10 Nov., 1993. ROM 68757, 3(10.5–18.0), Ko Hi, bay on S coast about middle of its length, 75 m W of RW93-05, fringing reef, 7.741667, 98.375556, 90 % live coral ( Astreopora , Pavona , favids, Porites , Acropora ), little algae, visibility 9 m, 6.1–11.0 m, rotenone, field # RW 93–06, 12 Nov., 1993. ROM 68758, 2(18.0–22.4), Ko Hi, bay on S coast about middle of its length, 75 m N of RW93–06, isolated patch reefs with sand, 7.741944, 98.375556, different corals, 50–50 live/dead coral, several stands of Acropora staghorn, visibility 6 m; 4.9 m, rotenone, field # RW93–07, 12 Nov., 1993. ROM 68759, 2(14.5–16.1), Patong Beach, off Sandy Beach near north tip of bay, coral slope (45°) to flat silt bottom, 7.92083, 98.27111, 80-90% live coral ( Pavona , Astreopora , encrusting corals, favids, etc.), visibility 7.6 m, 7.6–12.8 m, rotenone, field # RW 93–08, 13 Nov, 1993. ROM 68760, 2(17.8–18.0), Kata Bay, W side, 20 m E of small island named Ko Pu, 7.806944, 98.292222, large Porites bommie surrounded by some live ( Pavona , Pectinia ) coral, visibility 6 m, 3.0– 8.2 m, rotenone, field # RW 93–09, 14 Nov., 1993. ROM 68761, (20.7), Ko Racha Yai, E coast near N tip, heavy patch reef, 7.604167, 98.380556, Porites , Acropora (staghorn), a little silt, visibility 12 m, 3.0– 7.6 m, rotenone, RW 93-12, 16 Nov., 1993. ROM 68762, 10(16.4–26.5), Ko Racha Yai, bay in middle of N coast, 250 m from beach and 100 m from E arm of bay, beach rock arch with live coral, sand/patch reef, 7.607778, 98.368611, Acropora , Porites , Pectinia coral, Millepora , visibility 9 m, 6.1–10.7 m, rotenone, field # RW 93–15, 17 Nov., 1993. ROM 68763, 5(18.5–21.5), Ko Racha Noi, SE end, 200 m N of RW93-17 (off last beach before short break to next island), huge (4.6 m diameter) beach rock bommie surrounded by sand and patch reef, 7.470833, 98.326389, Pectinia , Pavona , Acropora , Pocillopora , visibility 12 m, 1.5–9.1 m, rotenone, RW 93–18, 18 Nov., 1993. ROM 69250, (20.3), Ko Nipit (Nipit Island), north coast, 6.485556, 99.296667, 6 m, Tea Seed extract, 12 Dec., 1994, coll: U. Satapoomin.

Tissues: ROM T 00471, (17.7) , collected with ROM 68761 . ROM T 03797 – T 03803, 7 , just off Bangthao Beach , 7.98721, 98.28465, 2008, coll: U. Satapoomin .

Non-types: MPM 31145, 13 (10.1–23.8), Ko Mai Thon, NW tip, patch reef, 7.761111, 98.479167, wide variety of corals, visibility 7.6 m, 4.6–8.5 m, rotenone, RW 93–25, 23 Nov., 1993 .

Diagnosis. A species of Trimma with second spine of first dorsal fin reaching posteriorly to between base of spine and base of 4 th ray of the second dorsal fin when adpressed, at least some branched pectoral fin-rays, fifth pelvic fin-ray unbranched, scales present in predorsal midline, no cheek or opercular scales, 15 or more total gill rakers, cheek with 6 papillae in row c, and a bony interorbital of less than 55% the width of the pupil, posterodorsal interorbital trench not extending laterally beyond 5 th papilla of row p. Cheek and anterior part of head with orange to red spots (light unpigmented areas in preserved specimens) less than pupil-diameter in size, a diamond-mesh pattern formed by melanophores thickly lining entire scale pockets on nape and body.

Description. The description is based on the holotype and up to 19 paratypes selected from lots ROM 068095, ROM 69250, ROM 068093, ROM 68094, ROM 68762, ROM 68764, and ROM 68763. Dorsal fin VI + I 8– 9 (9.0), second spine of first dorsal fin reaching to between base of dorsal spine and 4 th fin-ray of second dorsal-fin ( Fig. 1 ), third dorsal spine reaching posteriorly to between inter-dorsal space to base of spine of second dorsal fin, first ray of second dorsal fin branched (75%) or unbranched, remaining fin rays branched except for posterior element of last ray, fin reaches posteriorly 56– 64 –85% (64.13%) distance between base of last ray and first exposed dorsal procurrent caudal-fin ray; anal fin I 9, first ray unbranched in 17 of 20, fin reaching posteriorly 47– 60.1 –70% (60.1%) distance between base of last ray and first exposed ventral procurrent caudal-fin ray; pectoral fin 19– 20 (19.4) with 3– 4 –6 dorsal and 4– 7 –9 ventral unbranched rays and 6– 9 –13 branched rays in central portion of fin, fin reaching posteriorly to vertical above urogenital papilla to base of anal spine; pelvic fin I 5, fifth ray unbranched and 48– 56 –67% (52.4%, 18) length of fourth ray, which reaches posteriorly to between base of anal spine to 4 th anal fin-ray, pelvic rays 1–4 with single sequential branch point; basal membrane either attached to sides of belly just lateral to midline or forming narrow fold across midline dorsal to last pre-pelvic scale; no fraenum. Lateral scales 23 –24 (23.1); anterior transverse scales 10 –11 (10.1); posterior transverse scales 8– 9 (9.0); cheek and opercle scaleless; predorsal midline crossed by 6– 7 –8 (7.4) irregular scale rows, area in front of first dorsal spine scaleless for about 2 scale-widths but no fleshy crest present, anteriormost extent of scales to just posterior to posterior margin of eye; 3 vertical rows of cycloid scales on pectoral-fin base with 1– 2 scales in anteriormost row, 4– 5 in second row and 5 in outer row; 7 –8 (7.1, 16) cycloid scales in midline anterior to pelvic-fin base; area between pelvic spine and ventral margin of pectoral-fin base with cycloid scales; anterior few rows of scales in midline of belly cycloid; anteriormost row of body scales beneath axil of pectoral-fin base of either cycloid or ctenoid scales. Circumpeduncular scales 12, scale rows in midline between base of last anal ray and first ventral procurrent caudal-fin ray 8– 9 (8.3, 19). Upper jaw with outer row of about 8–10 spaced, enlarged curved canines reaching to distal end of premaxilla, space between adjacent teeth about equal to canine height, gradually decreasing in size posteriorly; several irregular rows of small conical teeth behind outer teeth, gradually decreasing in size and becoming reduced to single row, continuing posteriorly to distal tip of premaxilla; innermost few teeth near symphysis slightly larger and posteriorly oriented. Lower jaw with 4–6 enlarged, spaced, curved canines in outer row reaching to bend of dentary, space between adjacent teeth about equal to canine height; 2–3 irregular rows of slightly curved small teeth at symphysis to dentary bend; innermost row half-length of outer and reaching posteriorly to just beyond bend of dentary, continuing as a single row of small straight conical teeth to dorsal rim of coronoid process. Tongue broadly truncate. Gill opening extending anteroventrally to below mid- to posterior margin of pupil; gill rakers 4 –5 + 13– 14 –15 = 18 –19 (4.1 + 14.0 = 18.1). Anterior naris in short tube reaching anteriorly to above anterior margin of upper lip, posterior opening pore-like with raised rim, separated from bony front of orbit by 1 –1.5 times its diameter, nasal sac raised and on anterior half of snout. Bony interorbital width 26– 27 –37% (31.4%) pupil diameter; moderate U-shaped interorbital trench with no median raised fleshy ridge; narrow, poorly developed postorbital groove ending at papilla 5 of row p ( Fig. 2 B ); epaxialis reaching anteriorly in midline to vertical above posterior margin of pupil; no dermal ridge in midline of nape extending anteriorly from origin of first dorsal fin although the midline is scaleless for a space of about two scale-widths immediately anterior to first dorsal fin spine. Bony width of interorbital 26– 27 –37 (31.4). Caudal peduncle depth as percentage of caudal peduncle length 41– 42 –52 (45.8); head length as percentage of SL 29– 31 –33 (30.3%); as percentage head length: horizontal eye diameter 33– 35 –40 (36.5%); snout length 19– 24 (22%); cheek depth 20– 30 –31 (25.4%). Cephalic sensory papillae as in Fig. 2 . Number of papillae in each row: a = 6; b = 6– 9 –10 (8.0); c = 6; cp = 1; d = 7– 11 (8.9); dʹ = 7– 12 –14 (10.1); e-anterior = 14– 15 –21 (16.6); e-posterior = 16– 20 –24 (20.2); i-anterior = 8– 9 (9.0); i-posterior = 9– 10 –12 (9.9); p = 6; r = 2; f = 3– 4 (3.6); cs” = 3 –4; g = 2– 6 (4.1, 11); n = 1; x = 5– 7 (5.9, 19); u = 5; z = 5– 7 –8 (6.6); ot = 13– 18 (16.1); os = 6– 7 –8 (7.2, 18); oi = 4– 6 –7 (5.2). One specimen with a supernumerary papilla in row a between papillae 4 and 5. Caudal fin of holotype with 3 dorsal and 3 ventral segmented unbranched rays, and 6 dorsal and 5 ventral segmented branched rays; but 8 of 20 specimens with 2 ventral unbranched segmented rays and 6 branched segmented rays.. Abdominal/caudal vertebral transition type unknown, but probably type B given the narrow bony interorbital and non-schooling benthic habits of the new species.

Colour pattern. Live, not recorded.

Freshly collected, based on 35 mm colour slide of four paratypes by RW (3 shown in Fig. 1 ), two specimens collected and photographed by Ukkrit Satapoomin, and a web-based image by Hiroshi Senou. A 23.1 mm SL female (ROM 68095; Fig. 1A ) with background colour of pale grey-brown with numerous half-pupil sized orange spots and larger blotches on head and body, often outlined with melanophores. In most cases, entire scale pocket on head and body strongly outlined with melanophores, which form an overall mesh-like diamond pattern. Orange head spots/blotches include anterior snout and tip of lower jaw; spot on posterior premaxilla beneath anterior margin of pupil (neither margined with melanophores); two spots in vertical row on posterior part of cheek and in line with posterior margin of eye, with upper one outlined with melanophores and the two spots just joining each other; a darker, much redder spot on branchiostegal membranes beneath vertical limb of preopercle; spot over subopercle and another over posterodorsal part of opercle, both margined dorsally with melanophores; round spot strongly margined with melanophores over upper part of vertical limb of preopercle level with ventral one-third of eye; a>-shaped orange line about one scale wide above this; pupil-diameter long orange oval strongly outlined with melanophores directly above opercular spot and similar, slightly larger, blotch posterodorsal to it. Series of eight rather similar orange blotches across dorsum between middle of first dorsal fin and first procurrent caudal fin rays, both blotches and light interspaces roughly two scales wide. Another series of smaller blotches below and between these, fading out on peduncle, bases of numerous scales, especially those of midlateral series, with small orange spot; a few indistinct orange spots/blotches along ventral surface from anal-fin origin posteriorly. First dorsal fin with half pupil-diameter elongate orange-red oval spot between first two spines about half-pupil width above dorsum and similar more rounded spots on shafts of fifth and sixth spines; membrane of fin sprinkled with melanophores. Second dorsal fin with 1–2 rows of orange/red elongate spots along proximal one-third of shafts of spine and rays, with very vague distal yellow-orange stripe distally; membrane of fin well supplied with melanophores. Anal fin with similar density of melanophores in membrane, and fin rays suffused with orange. Caudal fin with dense melanophores in membranes and two irregular bars made up of orange spots. Pectoral-fin base with small orange spot on upper base and another more ventrally liberally overlain with melanophores; fin rays pinkish. Pelvic fin light yellow with numerous melanophores. Iris dark above and orange/silver below. A 24.6 mm SL male (ROM 68094, Fig. 1B ) virtually identical in colouration, although an additional small orange spot present in middle of predosal midline, spots in second dorsal fin better defined, those along dorsum essentially fade out posterior to middle of second dorsal fin, upper pectoral fin spot invested with melanophores, and upper portion of iris dark purple. A 25.5 mm SL female (ROM 68093, Fig. 1C ) is again almost identical, although two vertically aligned spots on posterior part of cheek well separated and caudal fin with additional orange spots. A 20.3 mm SL female (ROM 69250) with two vertically aligned orange spots on cheek fused together forming broad “8”, and spot behind eye and>-shaped line continuous. Two other specimens, photographed by Ukkrit Satapoomin, have posterior pair of cheek spots well separated, and orange spots in first dorsal fin forming a basal stripe, as does specimen photographed by Hiroshi Senou (http://fishpix.kahaku.go.jp/fishimage-e/search.html, image # KPM-NR 44869).

Preserved. Background pale straw-yellow with scale pockets strongly outlined with brown melanophores, usually several pigment cells wide (blue arrows, Fig. 3 ). Scales, especially anterodorsally on body, with thin line of tiny black melanophores along distal rim of exposed portion of scale (green arrows, Fig. 3 ). Large brown melanophores scattered over entire body, except absent or few in number in areas represented by orange spots on head (especially cheek and opercles) and on belly, where confined to scale margins if present. Melanophores surrounding light areas (= orange spots in life) on cheek and opercles generally larger and more diffuse than neighbouring pigment cells. Iris with melanophores ventrally but not dorsally.

Etymology. Named “ukkriti” in honour of Ukkrit Satapoomin (Director of Marine Resources Conservation Division, Department of Marine and Coastal Resources, Government of Thailand), who not only acted as liaison, organizer and participant in my field work at the Phuket Marine Biological Station in 1993, but who continued to collect and send me valuable specimens of reef gobies after we left, as well as making a special and successful effort to obtain specimens of this species for DNA barcode analysis.

Distribution. Currently positively recorded only from the seas around Phuket, on the western coast of Thailand.

Comparisons. This species keys out in Winterbottom’s (2019) key to the species of Trimma to couplet 78, where it stalls because the posterior interorbital trench in T. ukkriti does not extend laterally beyond the 5 th papilla of row p (vs. trench reaching to the dorsal-most papilla of row a as in couplet 78a, or to at least to the last, or 6 th, papilla of row p as in couplet 78b). The species in the couplet 78 grouping, none of which has yet been recorded from Thailand, are: T. insularum Winterbottom & Hoese, 2015 , T. lutea Viviani, Williams & Planes, 2016 (both from couplet 79), T. maiandros Hoese, Winterbottom & Reader, 2011 , T. squamicana Winterbottom, 2004 , and T. hamartium Winterbottom, 2018 . These species of Trimma share the following combination of character states with T. ukkriti : scales present in the predorsal midline, fifth pelvic fin-ray unbranched, no cheek or opercular scales, at least some branched pectoral-fin rays, cheek with 6 papillae in row c, a bony interorbital of less than 55% the width of the pupil, and 15 or more total gill rakers. Note that most specimens of T. insularum and T. maiandros lack scales in the predorsal midline.

None of these species has small (<pupil-diameter) orange/red spots on the cheek, opercles and pectoral-fin base, and only two of them may exhibit obviously darkened scale pockets on the body and nape forming a mesh-like diamond pattern ( T. lutea and T. maiandros ). The latter two species also share a vertical yellow marking along the vertical limb of the preopercle, which is a complete thin bar in T. lutea but two vertically elongate large blotches in T. maiandros . In T. ukkriti the markings in this location consist of two round spots in line with a “>”-shaped orangeyellow line dorsally above the middle of the eye. All but T. hamartium have an essentially a barred colour pattern on the body, although the dorsal half of the bars may be offset from the ventral part ( T. maiandros ) or absent ( T. sostra ). Quantitative differences in T. insularum from T. ukkriti include primarily details of the cheek papillae (11–12 and 14–15 vs. 14–21 and 16–24 in rows ea and ep respectively, and 12–14 vs. 15–18 in row ot). Trimma lutea differs further in having 10 (vs. 8–9) dorsal-fin rays, 18 (vs. 19–20) pectoral-fin rays, 6–7 posterior transverse scale rows (vs. 8–9), and 14 papillae in row ep (vs. 16–24). In T. maiandros , the second spine of the first dorsal fin reaches posteriorly only as far as the base of the spine of the second dorsal fin (vs. to between the bases of the spine to the 4 th dorsal fin-ray), there are 8 anal-fin rays, 16–18 pectoral-fin rays, of which 1–5 are branched (vs. 9, 19–20 and 6–13 respectively in T. ukkriti ), the midline of the predorsal is usually scaleless (scaled in 8% of specimens with a maximum of 5 scales (vs. 6–8)), there are 7 posterior transverse scale rows (vs. 8–9), and there are 11–12, 12–14 and 11–13 papillae in rows ea, ep and ot (vs. 14–21, 16–24 and 15-18 respectively). Trimma squamicana is a translucent species with six eye-diameter wide red bars on the body mostly below the midlateral septum and a seventh between the eye and the first bar (vs. no red bars), and there are 12–15, 13–16 and 12–16 papillae in rows ea, ep and ot (vs. 14–21, 16–24 and 15-18 respectively). The colour pattern in T. hamartium consists of a reddish head and a light yellow body, with the scale pockets lightly outlined (vs. spotted head and body with scale pockets strongly outlined) and there are 10–15, 12–16 and 11–15 papillae in rows ea, ep and ot (vs. 14–21, 16–24 and 15-18 respectively).

The new species has a colour pattern when fresh that is very similar to the colour patterns of T. okinawae and T. readerae Winterbottom & Hoese, 2015 (compare Fig. 1 with Fig. 4 ), and was initially identified as the former species. An analysis of the COI barcode gene published by Winterbottom et al (2014) identified 8 discreet haplogroups named as one or other of these two species, with the samples from Thailand, described here as T. ukkriti (as Group 2), appearing in the phenogram well removed from the groups consisting of the remaining 7 haplogroups (minimum distance = 16.5% of the COI base pairs). It is not germane to this paper to compare the different colour patterns found among these haplogroups, other than to point out that none of them seems to share the extensive cross-hatch pattern of melanophores found on the nape and body of T. ukkriti , nor, in most cases, are the scale edges bearing the cteni rimmed with a narrow line of small black melanophores. Additionally, they all have 5 papillae in row c on the cheek (vs. 6 in T. ukkriti ). Trimma okinawae from Japan (the type locality of that species) has a vertical bar of orange/red on the cheek below the posterior margin of the eye when fresh or alive (see Fig. 4 , A–C) whereas T. readerae (type locality: Great Barrier Reef) usually has a pair of vertically aligned orange spots ( Fig. 4 , D–E). Samples from different haplogroups may have either of these conditions (e.g. two spots in Fig. 4 F , from Rabaul, New Britain). While most images of T. ukkriti have two spots in this position, there is one photograph where the spots are completely fused to form a bar, and another where they are partially joined to form a figure-of-eight.

Seven other species of Trimma have been recorded from the vicinity of Phuket, but none of these has the distinctive mesh-like colour pattern and orange/red spots of T. ukkriti .

Figures

FIGURE 1. Trimma ukkriti, paratypes, Phuket, Thailand. A: 23.1 mm SL female, ROM 68095; B: 24.6 mm SL male, ROM 68094; C: 25.6 mm SL female, ROM 68093. Photos: R. Winterbottom.

FIGURE 2. Trimma ukkriti, paratype, 28.9 mm SL, ROM 68095, Ko Hi, Phuket. Left lateral (A) and dorsal (B) views of head to show head papillae, specimen stained with cyanine blue. Papillae rows connected by thin green lines. Photo and image collation by R. Winterbottom.

FIGURE 3. Trimma ukkriti, paratype, 23.5 mm SL male, ROM 68764, Ko Racha Yai, Phuket. Left lateral view of head and anterior body to show colour pattern of preserved specimens. Photo: R. Winterbottom.

FIGURE 4. Examples of the fresh/live colouration of members of the Trimma okinawae/readerae complex. A: T. okinawae, Amami Is., KPM-NR 108727, H. Senou; B: T. okinawae, Ie-jima I., Okinawa Is., KPM-NR 48401,T. Nomura; C: T. okinawae, Kerama I., Okinawa Is., KPM-NR 142270, K. Uchino; D: T. readerae, Yonge Reef, Queensland, AMS I.20784-020, D. Hoese; E: T. readerae, Lizard I., Queensland, ROM 38329, R. Winterbottom; F: T. okinawae, Rabaul, New Britain, ROM 92116, R. Winterbottom.