Trimma caudomaculatum Yoshino and Araga in Masuda et al., 1975:272

Winterbottom, Richard, 2016, Trimma tevegae and T. caudomaculatum revisited and redescribed (Acanthopterygii, Gobiidae), with descriptions of three new similar species from the western Pacific, Zootaxa 4144 (1), pp. 1-53 : 19-28

Trimma caudomaculatum Yoshino and Araga in Masuda et al., 1975:272

Blotch-tailed Pygmygoby

Figs. 11–18 , 31

Trimma caudomaculata Yoshino & Araga in Masuda et al., 1975:272 (Narome, Okinawa I., Japan; also Yaeyama Ids and sight records from Izu Ids); Senou et al., 2004:99 (Japan)

Trimma caudomaculatum: Motomura et al., 2013:335 (Iou-jima and Take-shima Ids, Japan); Yano, 1998:29 (Iriomote Jima) Trimma tevegae (non Cohen & Davis, 1969:321): Shao et al., 1992:330, B, (Taiwan); Randall & Goren, 1993:22 (Pl. 4G, Maldives); Kuiter, 1998:209 (Maldives); Hayashi & Shiratori, 2003:39 (image No. 0 53, Japan; image No. 0 54, Saipan); Anderson, 2005:105 (Maldives); Winterbottom et al. 2014:88 (Group 7 only); Winterbottom & Hoese, 2015:87 (Rowley Shoals material only)

Material examined. Paratypes. FAKU 62260–62264, 5 (22.1–23.5), Japan, Okinawa Id, fringing reef off Nerome (~ 3m), hand net, Jan. 30, 1975. Originally catalogued as SMBL 75059–75063 .

Non-type material. Australia: Rowley Shoals: WAM P.28024.021, (26.9), Clerke Reef , 440 m from main passage, outer reef, 17°40'S, 119° 22'E, 35–40 m, 6 Aug. 1983, G. Allen & R. Steene . Indonesia: Timor Leste : ROM 93811, 4 (16.8–19.2), Manatuto Is, 08°30.997'S, 126°04.388'E, 45 m, clove oil , 21 Aug., 2012, M. Erdmann (plus tissue specimens, ROM T10884–10885). Japan: Ryukyu Ids: ROM T04142–04153, 12(24.2– 28.8), north of Ie-Jima Id , 18 m, 24 Apr., 2009, K. Yunokawa . Papua New Guinea: Milne Bay: ROM 101084, 2 (21.9−25.1), south side, wreck off WagaWaga , 10° 24.421’X, 150° 24.644’E, 10 m clove oil , 22 Mar. 2016, M.V. Erdmann (plus on tissue specimen, ROM T12783). Port Moresby : ROM 94498, 5 (16.6–23.2), Lion Id off Loloata Resort , 09°32.213'S, 147°16.688'E, 10 m , 8 June, 2013, M. Erdmann (plus tissue specimens ROM T12767–12768). Rabaul (New Britain), all specimens from Simpson Bay , Dawapia rocks, collected by R. Winterbottom and W. Holleman in 2011 : ROM 86599, (18.9), SE end of eastern rocks, hard and soft corals, hydroids, sea fans; almost vertical wall with small caves and overhangs, 04°14.164'S, 152°10.023'E, 19.5 m, clove oil, RW11-02CR 1, 19 Nov. ROM 86600, (24.7), off SW tip of the larger rock, varied hard and soft corals, sponges, hydroids, ascidians; caves and crevices in steep to vertical walls, fine sand substrate, 04°14.144'S, 152°10.010'E, 26.8 m, clove oil, RW11-13BR2, 25, Nov. ROM 88140, (18.7), S side, hard and soft corals, hydroid 'trees', sponges; steep reef slope, caves and crevices, 04°14.134'S, 152°10.038'E, 19.5 m, clove oil, RW11-04AR 2, 20 Nov., (plus tissue specimen, ROM T13156 , 17.5). ROM 92109, (21.3), SW side of the larger rock, hard and soft corals, sponges, hydroids; steep to almost vertical slope with small caves, fissures and crevices, many with fine sand substrate, 04°14.147'S, 152°10.029'E, 20.7 m, clove oil, RW11-08GR 1, 22 Nov. ROM T13147 , (19.7), S side, wide variety soft and hard corals, hydroids; steep slope with small caves, overhangs, crevices and gullies, 04°14.155'S, 152°10.034'E, 19.5 m, clove oil, RW11-03CR 1, 20 Nov., (tissue specimen only). ROM T13158 (15.8), S side, hard and soft corals, hydroid 'trees', sponges; steep reef slope, caves and crevices, 04°14.134'S, 152°10.038'E, 17.7 m, clove oil, RW11-04CR 2, 20 Nov., (tissue specimen only). Philippines: AMS I.21903-018, 4(9–20), north-east of Bolinao , channel west of Santiago Id, 16°25'N, 119°53'E, 3–15 m, 17 Apr., 1980, AMS party. Solomon Ids : Guadalcanal Id : ROM 46126, (17.9), Honiara, 2 km W of Point Cruz Yacht Club , reef off V.S.O. Lodge, isolated coral bommie, mostly soft and hard corals, sponges, hydroids, 09°25.557' S, 159°56.225' E, 21 m, rotenone, PN83-02, 19830504, P. Nichols & D. Evans . ROM 99082, 3 (18.2–25.4), 11.7 km NW of Honiara, wreck of the Hirokawa Maru (aka “ Bonegi 1”), east side and hold of wreck, 09°23.440'S, 159°52.817'E, 18–22 m, rotenone , 15 Mar., 1983, R. Winterbottom et al. ROM 99083, 4 (14.2–24.7), 11.7 km NW of Honiara, wreck of the Hirokawa Maru , break in west side of wreck, 09°23.440'S, 159°52.817'E, 18–22 m, rotenone , 14 Mar., 1983, R. Winterbottom et al. ROM 1911 CS, 7(10.0– 28.1), wreck of the Kyusyu Maru (aka the “ Ruiniu wreck”) about 12 km NW of Honiara, inside of wreck on vertical face of superstructure, soft and hard corals, sponges and hydroids, 09°21.159'’S, 159°50.609'E, 20–22 m, PN83- 01, 24 Apr., 1983, P. Nichols & D. Evans.

Diagnosis. A species of Trimma with a bony interorbital 73–100% pupil diameter, a fully scaled nape with the anterior rows ctenoid in adults, a second dorsal spine that may reach posteriorly as far as the anterior dorsal procurrent caudal fin rays in mature males and usually reaches to at least the middle of the second dorsal fin, usually unbranched pectoral-fin rays, an unbranched fifth pelvic-fin ray that is about 50% the length of the fourth ray, and a large dark blotch on the posterior caudal peduncle. Fresh, mature specimens> 18 mm SL usually have a blue stripe along the lateral midline of the body passing across the dorsal margin of the pupil, another blue stripe in the dorsal midline, a third beneath the eye across the upper cheek, and blue blotches just anterior to the eye, on the opercle, and the posteroventral side of the iris. The base of the caudal fin posterior to the caudal spot is suffused with magenta with diffuse tapering reddish streaks. Preserved specimens have a dark brown dorsal surface of the snout which is darker (often black) in the midline, with scattered, larger and much darker melanophores, there is a dark diffuse blotch between the front of the eye and the middle of the upper jaw, the cheek below the eye has a diffuse stripe of brown chromatophores which passes along the ventral edge of the orbit dorsally, and a brown spot on the chin just behind the symphysis of the lower jaw is usually lacking.

Description. The redescription is based on up to 27 specimens, 14.2–28.8 mm SL (mean 21.9) from 12 collections from the western Pacific, including 5 paratypes from Okinawa. Dorsal fin VI + I 8 (n = 27), second spine elongated, usually reaching to between middle and just past end of second dorsal fin in females, and between end of second dorsal fin and beginning of dorsal procurrent caudal rays in males (see Discussion and Table 1 ), all fin rays branched except for posterior element of last (first dorsal ray unbranched in one specimen), length of last ray of dorsal and anal fin sexually dimorphic (see Discussion); anal fin I 8 (n = 27), first ray usually branched (unbranched in 1 specimen); last dorsal and anal rays elongated, more so in males than females (see Discussion); pectoral fin 14–15 (mean 14.0, n = 27; 15 in one), rays usually unbranched, but 1–5 rays in middle of fin branched in 9 specimens ( Japan, 6 of 10, Rabaul, 2 of 8, and Solomon Islands, 1 of 6); pelvic fin I 5, fifth ray unbranched and 48–65% (mean 53.4, n = 20) length of fourth ray, which reaches posteriorly to between urogenital papilla and base of fourth anal ray, pelvic rays 1–4 with a single sequential branch point; basal membrane only just forms a fold across midline beneath last prepelvic scale or attaches to sides of body near midline; no fraenum. Lateral scales 23– 24 (mean 23.1, n = 22), where 24 a small cycloid scale present at beginning of series; anterior transverse scales 8–10 (mean 9.2, n = 19); posterior transverse scales 7–9 (mean 8.0, n = 19); predorsal scales 10–13 (mean 11.8, n = 22), anteriormost scales usually ctenoid although some of scales rimming eye may be cycloid, scales reaching anteriorly to above anterior to middle of pupil; cheek with 1–3 rows of cycloid scales, uppermost row (if present, 13 of 22) of 1–2 scales (mean 1.2), middle row of 7–8 scales (mean 7.4, n = 22), lowest row (18 of 22) of 1–4 scales (mean 2.2); opercle with 3–4 horizontal rows totalling 7–13 mostly cycloid scales (mean 9.3), often 1–2 very small supernumerary cycloid scales dorsally, some larger, more central, scales usually ctenoid, dorsalmost row with 2–4 scales (mean 3.7, n = 13), second row 2–4 (mean 3.0, n = 13), third row 1–4 (mean 1.5, n = 13) and ventralmost row, if present of 1–2 (mean 1.5, n = 4); pectoral fin base with 3 (once 4, first row of 2) vertical rows of cycloid scales, with 1–3 in first row and 3–4 scales in next two rows; cycloid scales in midline anterior to pelvic fin base 6–9 (mean 7.5, n = 19); breast, area between pelvic spine and ventral margin of pectoral fin base, midline of belly and sometimes anteriormost row of body scales beneath axil of pectoral fin base with cycloid scales. Upper jaw with outer row of enlarged, curved, spaced teeth, decreasing slightly in size posteriorly almost to posteroventral tip of premaxilla, 2–3 irregular inner rows of small conical teeth grading posteriorly to single row extending posteriorly to just before end of outer row ( Fig. 13 A). Lower jaw with outer row of about 6 enlarged, curved, spaced canines ending at bend in dentary, followed by 2–3 rows of smaller conical teeth which grade posteriorly to single row near dorsal tip of coronoid process of dentary, an innermost row equal in size to outer teeth, spaced, curved, gradually decreasing in size posteriorly, row ending at anterodorsal tip of coronoid process of dentary ( Fig. 13 B; description of teeth based on 28.1 mm SL cleared and stained specimen from Guadalcanal, Solomon Ids). Tongue truncate with rounded edges, sometimes with central tip. Gill opening extending anteroventrally to below mid-pupil; gill rakers 3–5 + 14–17 = 18–21 (mean 3.8 + 15.1 = 19.0, n = 24). Anterior nares 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 2–3 its diameter (mean 2.8, n = 18), nasal sac raised and on anterior onethird of snout. Bony interorbital 73–100% (mean 92.4, n = 22) pupil diameter; shallowly concave with median fleshy ridge forming broadly rounded W in cross section; epaxialis extending anteriorly to point above middle of pupil. Caudal peduncle depth as percentage caudal peduncle length 34.1–45.4 (mean 40.8, n = 22); head length as percentage SL 27.3–35.2 (mean 30.2, n= 22); as percentage head length, horizontal eye diameter 32.5–38.5 (34.7, n = 22); snout length 23.2–29.2 (mean 25.5, n = 22), cheek depth 12.7–22.9 (mean 16.6, n = 22). Cephalic sensory papillae as in Fig. 14 , number of papillae in each row given in Table 2 . Abdominal/caudal vertebral transition Type A, with haemal arches of first two caudal vertebrae expanded ( Fig. 15 , a 29.9 mm SL cleared and stained male from Solomon Ids).

Colour pattern. Live, based on underwater photograph taken at Lion Id off Port Moresby, PNG (anterodorsolateral view, Fig. 16 A): head and body reddish-brown, somewhat darker dorsally, with black eyediameter blotch over last few scales on peduncle and onto bases of caudal fin rays. Half-pupil width blue stripe in dorsal midline from tip of snout to origin of first dorsal fin, another from just behind maxilla across top of eye just above pupil, after which it widens to just more than height of midlateral scale row and ends just anterior to black caudal blotch where it expands into a saddle over dorsal part of peduncle with a short extension ventral to midlateral line; short blue stripe beneath orbit, separated from it by distance equal to its width, from proximal tip of upper jaw passing slightly ventrally to reach posterior margin of branchiostegal membrane, area below this pale yellow-orange, margin of lower jaw darker than surroundings; half-pupil diameter irregular blue blotch on middle of anterior opercle level with lower one-third of eye, short blue stripe at 5 o’clock position on iris. Spines of first dorsal fin dark, fin membranes very light blue to transparent; elements of second dorsal fin similar but lighter, a pupil-diameter wide basal light lavender stripe followed by orange stripe that is wider posteriorly, fin membrane distal to this pale blue; anal fin similar (except that basal band not visible in image), caudal fin rays black basally with dark red irregular band following contours of dark blotch posteriorly with irregular short extensions on to caudal fin which grade into vague yellow-orange stripes, fin pale lavender posterior to red band, gradually fading to yellow-orange distally. Pelvic fin very light blue with broad diffuse light yellow stripe in middle of fin; pectoral fin apparently hyaline. There are numerous images of live specimens of T. caudomaculatum on the Image Database of Fishes of the Kanagawa Prefectural Museum of Natural History (KPM-NR — see http://fishpix.kahaku.go.jp/ fishimage-e/search.html). These images show some variation in background colour (from dark red to dirty yellow), in degree of development of blue stripes on body, and in intensity of colouration of unpaired fins. Some specimens at rest on substrate may show light pupil-diameter sized light spots across dorsum, first at origin of first dorsal fin, second at origin of second dorsal fin, and third at end of first dorsal fin. These spots may extend diffusely ventrally to join blue lateral stripe (e.g. Motomura et al., 2013:335, lower image).

Freshly collected, based primarily on eight images (15.8–24.7 mm SL) from Dawapia Rocks, Rabaul, New Britain (e.g. Fig. 16 B), three of which represent tissue specimens. Figured specimen (21.5 mm SL female, ROM 92109) similar to live specimens, but background colour dark orange-brown, blue lateral stripe slaty grey (dorsal stripe not visible) as is stripe across cheek onto branchiostegal membranes, stripe across dorsal part of eye and onto snout very dark blue, blue streak across middle of opercle diffuse and almost black, dark blue spot at 5 o’clock position on iris. Dorsum with scale margins (especially apices of scales) darker forming vague reticulated dark blotches, chin and bottom half of cheek pale orange; throat, breast and belly from lower pectoral base to end of anal fin off-white and relatively clearly demarcated from orange body above. Tip of upper jaw and lip of lower jaw dark. Middle stripe in second dorsal and anal fins fin yellowish, no trace of lavender wash on caudal fin, dorsal margin of pectoral fin base with thin diffuse dark margin. Both photographed male specimens (17.9 mm SL, ROM 88119; 18.2 mm SL, ROM 88140) with dark orange stripe in first dorsal fin above basal stripe which is not apparent in photographed females, stripe in second dorsal fin bright yellow margined with red. Some specimens with central portion of abdomen with yellowish suffusion. Anaethetized specimen from Timor Leste ( Fig. 16 C) with greenish dorsum, reddish-yellow abdomen behind pectoral fin base grading posteriorly to yellow below midlateral line, margined dorsally and ventrally with thin diffuse red stripes, eye rotated about 30° clockwise by supporting pin so that dark blue stripe above pupil obliquely oriented, bordered by thin red lines, as are blue blotch on snout and blue line below eye, anterior of upper jaw and lower lip red, basal stripe in dorsal and anal fins bluish and yellow stripes margined distally with blue, caudal fin blue with diffuse yellow streaks parallel to fin rays, lateral stripe greyish-blue, basal three-quarters of pelvic fin yellow, fin rays distal to this bluish, pectoral fins apparently hyaline.

Preserved. (Note: specimens which have lost scales tend to have a somewhat distorted colour pattern). Body pale straw-yellow, dorsum with small, rounded dark brown chromatophores which tend to be somewhat more concentrated around scale pockets and at apices of scales, lateral stripe of larger, more diffuse brown chromatophores along scale row immediately above midlateral septum (including especially dorsal extension of stripe on posterior part of peduncle), lower half of body with small rounded brown chromatophores decreasing in density ventrally, and intermingled with slightly larger and much darker rounded chromatophores ( Fig. 17 ); caudal blotch formed by concentration of both types of chromatophores. Upper two-thirds of head heavily pigmented with diffusely rounded brown chromatophores, more densely concentrated between eye and middle of upper jaw, in slightly oblique stripe just below eye on cheek, at mid-region of opercle, along upper base of pectoral fin, upper lip and margin of lower lip ( Fig. 18 A—see red arrows); lower half of cheek and lower jaw with very few chromatophores. Upper surface of snout with scattered irregular brown chromatophores, concentrated into a central dark stripe interspersed larger, darker brown chromatophores (red arrows in Fig. 18 B) which broadens out at first predorsal scale to become vague stripe in midline of nape where scale pockets are slightly outlined.

Etymology. The name refers to the “darkish red caudal fin base” (Yoshino and Araga in Masuda et al., 1975:272).

Distribution. Based only on material examined in this study, the range of T. caudomaculatum spans an area from the Ryukyu Islands of Japan south-east to the Solomon Islands and south-west west to Rowley Shoals, Western Australia ( Fig. 11 ). The species has not yet been recorded from Palau, but is present in the Philippines. Based on underwater photographs, it appears to range at least as far west as the Maldive Islands (see, e.g. Randall & Goren, 1993, Pl. 4G). However, specimens and tissues are needed to test this identification.

Comparisons. See under T. tevegae for differences between various similar-looking species.

Discussion. The length of the last dorsal and anal fin rays exhibit sexual dimorphism in this species. In females, the last dorsal fin ray extends 33–57% (mean 46%, n = 10) of the distance between its base and the base of the first dorsal procurrent fin ray, and for males 34–89% (mean 70.9%, n = 10). The difference between males and females for the length of this fin ray increases with SL (ANCOVA, p-value for SL*sex interaction = 0.0448, Fig. 12 B). The last anal ray reaches 32–54% (mean 43.2%, n = 9) of the distance to the first ventral procurrent ray in females. The values for males are 48–96% (mean 67.6%, n = 14), and the ray is significantly longer in males than in females (ANCOVA, p-value for sex = 0.000248). Similarly, the second dorsal spine of the first dorsal fin is sexually dimorphic, with females having a shorter spine. Values for the abducted posteriormost extent of the second dorsal spine were assigned arbitrary values, with 1 for the spine of the second dorsal fin, incrementing by 1 for each fin ray base, and incrementing further, where necessary, for each scale on the dorsal surface of the caudal peduncle. In females, the spine reached posteriorly to between the base of the second dorsal ray and the first scale posterior to the dorsal fin (assigned values of between 3 and 10), with a mean at the base of the fifth ray (n = 10). In males, the spine extended to between the base of the second ray and the base of the first procurrent fin ray (assigned values between 3 and 17), with a mean value of 10.9 (i.e. to the second scale behind the dorsal fin on the peduncle, n = 13). The spine is significantly longer in males than females (ANCOVA, p-value for sex = 0.0079).

At Dawapia Rocks, Rabaul , T. caudomaculatum was only collected between 17.7–26.8 m . The specimens from Timor Leste , Indonesia were taken in 45 m . Motomura et al. (2013) record this species from between 6–55 m in Japan, and the holotype and some of the paratypes were collected at Okinawa in as little as 3 m (Yoshino and Araga in Masuda et al., 1975).

Two specimens from Guadalcanal, Solomon Islands (ROM 99083, 14.6–16.6) were provisionally identified as this species based mainly on the colouration of the top of the snout and the dark diffuse blotch between the eye and the maxilla (the cheek below the eye and the opercle are abraded, and the second dorsal spine in both is broken). They differ from all other specimens in this species complex examined to date in having mostly or all body scales cycloid. The two other specimens in this lot, a larger (24.7 mm SL) and a smaller (14.2 mm SL) specimen, had the normal condition of predominantly ctenoid body scales. It is not clear whether the specimens with cycloid scales represent an anomaly, or whether they represent a different, currently unrecognized, species. Further collecting in the Solomon Islands with colour images of live and freshly collected specimens, along with tissue samples, are needed before this issue can be adequately addressed. Data from the two specimens with cycloid scales have been omitted from the description of T. caudomaculatum given above.

Figures

FIGURE 11. Map of the distributions of the Trimma tevegae subgroup. Inverted triangle = T. burridgeae; square = T. caudomaculatum; triangle = T. corerefum; diamond = T. hollemani; circle = T. tevegae. Pink fill = tissue specimens available; blue fill = formalin-fixed specimens only; green fill = literature / photographic records only.

FIGURE 12. Results of the ANCOVA analysis. A: Trimma tevegae, length of second dorsal spine versus Standard Length (SL). B: Trimma caudomaculatum, length of last dorsal fin ray versus SL. See text for units. Graphs by K. Alofs.

FIGURE 13. Trimma caudomaculatum, 28.1 mm SL, ROM 839 CS, jaw teeth. A: ventromedial view of right upper jaw; B: dorsomedial view of right lower jaw. Specimen stained with alizarin and alcian blue. Photos by R. Winterbottom.

FIGURE 14. Trimma caudomaculatum, head papillae. A: left lateral view of the head of a 22.1 mm SL male paratype, FAKU 62264, Japan. B: dorsal view of the head of a 22.9 mm SL male, ROM 94498, Port Moresby, PNG. Yellow lines connect papillae in a given row (see Fig. 4 for nomenclature of lines), red arrow points to supernumerary papilla. Specimens stained with cyanine blue. Photos by R. Winterbottom.

FIGURE 15. Trimma caudomaculatum, 29.9 mm SL male, ROM 839 CS, Solomon Is. Anterior view of 10 th abdominal (A), and 1 st to 3 rd caudal vertebrae (B – D respectively). Abbreviations: C = centrum; HA = haemal arch; HC = haemal canal; HS = haemal spine; NA = neural arch; NS = neural spine; PR = pleural rib. Specimen stained with alizarin red. Photos and image enhancement by R. Winterbottom.

FIGURE 16. Trimma caudomaculatum. A: live specimen, ROM 94498, Port Moresby, PNG. B: freshly collected, ROM 92109, Rabaul, New Britain. C: freshly collected, ROM T 10885, Timor Leste, Indonesia. Note that the second dorsal spine in B and in C is broken off at the level of the tip of the first spine (B) or just beyond this (C), and that the eye is rotated about 30 ° clockwise by the support pin in C. Photos: A and C by M. V. Erdmann; B by R. Winterbottom.

FIGURE 17. Trimma caudomaculatum, preserved 21.5 mm SL female, ROM 92109, Rabaul, New Britain. Left lateral view of body from middle of first dorsal fin to caudal peduncle to show distribution of chromatophores. Photo by R. Winterbottom.

FIGURE 18. Trimma caudomaculatum, preserved 21.5 mm SL female, ROM 92109, Rabaul, New Britain. A: left lateral view of head. B: dorsal view of head. See text for reference to red arrows. Photos by R. Winterbottom.

FIGURE 31. Trimma hollemani, preserved specimens. A: Left lateral view of body, 27.6 mm SL male paratype, ROM 85341, Raja Ampat; B: dorsal view of snout pigmentation, 17.4 mm SL male paratype, ROM 85256; C: dorsal view of snout pigmentation, 17.1 female paratype, ROM 84886. Photos by R. Winterbottom.