Trimma wangunui, Winterbottom & Erdmann, 2019

Winterbottom, Richard & Erdmann, Mark V., 2019, A new species of Trimma (Pisces; Gobiidae) from the Western Pacific Ocean, Zootaxa 4577 (3), pp. 571-578 : 572-577

Trimma wangunui new species

Wangunu’s Pygmygoby

Figs. 1–6

No published names pertain to this species.

Material examined. Holotype. ROM 108308 , 20.8 mm SL female, Papua New Guinea, Milne Bay Province, Little China (about 3.5 km SW off Nuakata Island ), 10° 18.692'S, 150° 58.477'E, clove oil, 10–14 m, field # MVE- 18-035, 8 May 2018, M.V. Erdmann & N. Wangunu.

Paratypes: ROM 108312 , 2 (19.3-20.6) , collected with the holotype. ROM 101392 , 2 (9.7–9.8) , same locality as holotype, clove oil, 10 m, field # MVE-16-085, 25 Dec., 2016, M.V. Erdmann . ROM 101358 , (14.7) , Timor- Leste, Adara MPA, Atauro I., 08° 11.476’ S, 125° 34.079’ E, clove oil, 50 m, field # MVE-16-032, 16 Jun., 2016, M.V. Erdmann. Tissues: ROM T 010695 , collected with ROM 101358 . ROM T20886 , 17.4 mm SL male, same locality as holotype, 10 m, clove oil, field # MVE-16-021, 26 May, 2016, M.V. Erdmann & N. Wangunu .

Non-types: USNM 436303 (18.0, tissue only, specimen not photographed), Philippines, Batangas, Verde Island, San Agustin East Barangay, north side of island, 13.5639, 121.067, 8– 16m, rotenone, Field # VERDE- 2015-26, 17 Apr 2015, J.T. Williams, D. Catania & D. Dumale.

Diagnosis. A species of Trimma with scales in the predorsal midline, no scales on the cheek or the opercle, an elongate second spine of the first dorsal fin reaching to the bases of the 2 nd –8 th second dorsal-fin rays when adpressed, all pectoral-fin rays unbranched, a branched fifth pelvic-fin ray with a full basal membrane, and yellow bars on the head with vertically elongate yellow spots on a brown body when freshly collected.

Description. The description is based on up to 7 specimens (9.7–20.8 mm SL). Dorsal fin VI + I 8, second spine elongated ( Fig. 1 ), reaching posteriorly when adpressed to between base of 2 nd –8 th ray of second dorsal fin (mean = base of 5–6 th ray, holotype to base ray 2, Fig. 1 ), first ray of second dorsal fin branched (unbranched in three), remaining fin rays branched except for posterior element of last ray, fin reaches posteriorly 46– 47 –48% (47%, n = 3) distance between base of last ray and first exposed dorsal procurrent caudal fin ray; anal fin I 8, first ray unbranched (n = 3), fin reaches posteriorly 32– 38 –49% (40%) distance between base of last ray and first exposed ventral procurrent caudal fin ray; pectoral fin 17, all rays unbranched, fin reaching posteriorly to region above urogenital papilla to anal spine; pelvic fin I 5, fifth ray with single dichotomous branch and 79– 84 –88% (84%) length of fourth ray, which reaches posteriorly to between bases of anal spine to 4 th anal ray, pelvic rays 1–4 with single sequential branch point; basal membrane full, almost to tips of 5 th ray ( Fig. 2 ); no fraenum. Lateral scales 23; anterior transverse scales 9; posterior transverse scales 7; cheek and opercle scaleless; midline of predorsal with 6– 7 –8 (7.2) scales, anterior 1–2 and last few rows may be cycloid, ctenoid in between; anteriormost scales on sides (may be ctenoid or cycloid) and top of nape reaching anteriorly almost to posterior margin of pupil; 2 vertical rows of cycloid scales on pectoral fin base with 2 in anteriormost row and 3 in posterior row; 7 –8 (7.3) cycloid scales in midline anterior to pelvic fin base; area between pelvic spine and ventral margin of pectoral fin base with cycloid (smaller specimens) or ctenoid (larger specimens) scales; anterior few rows of scales in midline of belly cycloid; circumpeduncular scales 12, scale rows in midline between base of last anal ray and first ventral procurrent caudal fin ray 8. Upper jaw with outer row of enlarged, spaced, curved canines to end of premaxilla, several rows of small conical teeth medial to this, decreasing in size and number of rows posteriorly to single row at end of premaxilla. Lower jaw with enlarged, spaced, curved canines to bend of dentary, small conical teeth in several rows near symphysis, innermost row somewhat enlarged, teeth reaching to coronoid process of dentary posteriorly. Tongue broadly truncate. Gill opening extending anteroventrally to below mid to posterior pupil; gill rakers 3 + 12– 13 = 15– 16 (3.0 + 12.7 = 15.7; n = 3). Nasal apparatus small, situated on anterior 1/3 of snout, anterior naris short tapering tube reaching anteriorly to above anterior margin of upper lip, posterior opening porelike with slightly raised rim, transverse width of pore about 65% length of nasal capsule, posterior margin of posterior naris separated from bony front of orbit by 2.5–3 times its transverse width, nasal sac only very slightly raised above surrounding area of snout ( Fig. 3 ). Bony interorbital width 20.8 –28.8% (25.9, n = 3) pupil diameter; shallow concave depression between eyes (between 3 rd and 4 th papillae of row p); slight postorbital groove; epaxialis reaching anteriorly in midline to vertical just behind posterior margin of pupil; no narrow ridge of skin in midline of nape extending anteriorly from origin of first dorsal fin. Based only on largest three specimens (19.3– 20.8): caudal peduncle depth as percentage caudal peduncle length 39.5– 40.8 (40.1); head length as percentage SL 28.3 –30.2 (29.3); as percentage head length: horizontal eye diameter 33.8– 38.7 (37.0); snout length 24.0– 24.8 – 26.9 (25.2); cheek depth 24.2– 29.0 (26.6). Cephalic sensory papillae as in Fig. 3 . Number of papillae in each row: a = 6; b = 4– 5 (4.3); c = 6; cp = 1; d = 4; dʹ = 5– 8 (7.3); e-anterior = 10– 13 (11.2); e-posterior = 11– 13 (12.2); ianterior = 7– 8 (7.8); i-posterior = 8– 9 (8.2); p = 6; r = 2; f = 3; cs" = 3; g = 2– 3 –4 (3.0); n = 1; x = 5– 6 (5.4); u = 5; z = 4 –5 (4.3); ot = 12– 13 (12.7); os = 4 –6 (5.0); oi = 4). Abdominal/caudal vertebral transition not examined.

Colour pattern. Live, not recorded. Freshly collected, (based on images of 5 specimens). Holotype ( Fig. 1A ): body with network of brown scale pocket margins 1/3 pupil diameter in width with vertically elongate yellow centres which become smaller and rounder towards caudal peduncle. Head and nape dark grey, diffuse yellowbrown bars on head, first from anterior margin of eye to middle of maxilla; second from anteroventral eye to end of maxilla; third from just posterior to eye level with dorsal margin of pupil inclined slightly anteroventrally to end on cheek just anterior to bend of preopercle; fourth from middle of dorsal margin of opercle to just posterior to bend of preopercle; and fifth along the posterior margin of the opercle, beginning from a level in line with the dorsal margin of the pupil, and extending ventrally to bend of operculum. Top of snout diffusely reddish; iris bright red with narrow white ring around pupil and some diffuse melanophores along anterodorsal and posteroventral rims, and small dark spot ventrally. Diffuse yellow stripe in dorsal fins just above base with scattered yellow spots/suffusions in body of fins, bordered distally with white/light grey. Anal fin similar, but with more intense yellow/green pigmentation in body of fin (note: broad dark stripe at base of fin caused by shadow from body due to flash angle). Caudal fin margined with white/light grey, membranes yellow fading somewhat distally. Pectoral fin with hyaline membranes and pinkish fin rays; pelvic fin with pinkish rays and light pigment in fin ray membranes. Paratypes from same locality (ROM 108312, 19.3 mm SL female; ROM T20886 , 17.4 mm SL male) very similar. Specimen from Timor-Leste (ROM 101358, 14.7 mm SL female, Fig. 1B ) lighter overall, with scale margins and centres with more diffuse pigmentation. Yellowish diffuse bar from anteroventral eye to middle of maxilla more distinct, iris with oblong patches of melanophores margined with yellow at 1, 4, 6 and 8 o’clock positions with thin, similar streak along anterodorsal margin; yellow stripe at base of dorsal fins more distinct; white/light margins of unpaired fins less obvious, some melanophores in pelvic fin membranes. Preserved, whole head and body liberally invested with large dark- to light-brown, irregularly-shaped melanophores, less dense on ventral 1/3 of body ( Fig. 4 ). Virtually no trace of bars on head, and little indication of light (yellow in life) centres to scale pockets, although posterior margins of scales on dorsum with very thin dark outline. First dorsal fin with scattered melanophores in proximal 1/4 and distal 1/3, membranes of second dorsal, anal and caudal fins fully invested with diffuse, elongate melanophores. Some similar melanophores in pelvic fin membrane, especially between inner rays, a few such melanophores in basal 1/3 of pectoral fin. Specimen from Timor-Leste very similar, but with less densely clustered and smaller, rounder melanophores. No traces of red or yellow pigment.

Etymology. Named for Noel Wangunu, one of Papua New Guinea’s foremost reef scientists and marine conservationists, who also assisted MVE in collections and local permits. This species has been informally referred to as Trimma RW sp 107.

Distribution and Habitat. Trimma wangunui is currently recorded only from off Nuakata Island in the Milne Bay Province of Papua New Guinea, from Atauro Island in Timor-Leste, and from Verde Island in the Batangas Province of the Philippines. It appears to be a rare species, with most specimens collected between 10– 16 m. At Nuakata and Atauro Islands, it was found living under large pieces of dead foliose coral rubble on a sandy bottom subject to moderate currents and wave action. It is apparently a solitary species, with only a single specimen collected from each piece of rubble examined.

Comparisons. Three other species of Trimma have a combination of scales in the predorsal midline, no scales on the cheek or the opercle, only unbranched pectoral fin rays, and a branched fifth pelvic fin ray: T. annosum Winterbottom, 2003 ; T. emeryi Winterbottom, 1985 ; and T. flavicaudatum ( Goren, 1982) . In the first two species the tip of the second dorsal spine does not, or only just, reaches the second dorsal fin when adpressed (to the base of the second ray in T. flavicaudatum , to between the bases of 2 nd –8 th ray in T. wangunui — Fig. 1 ). When alive or freshly collected, T. annosum has scale-sized red spots on the body, a large ovoid red bar over the upper 2/3 of the pectoral base, and a larger similar ovoid bar just posterior to the vertical limb of the preopercle, with, usually, a plain grey cheek; T. flavicaudatum has large red spots on the head, a red lower lip, with this colour extending posteroventrally to below the pupil, and often (but not always) a yellow caudal peduncle. In these two species, the 5 th pelvic-fin ray is shorter relative to the 4 th ray than in the other two (up to 65% vs.> 79%). Morphologically and in colour pattern, T. emeryi and T. wangunui are very similar, apart from the length of the 2 nd spine of the first dorsal fin (which reaches to the base of the spine of the seecond dorsal fin or anterior to this in T. emeryi ), and the apparent lack of discreet yellow spots and stripes on the body in T. emeryi (based on a photograph of a freshly collected specimen from Chagos, and underwater photographs of a specimen from D’Arros I., Seychelles that appears to be con-specific—see Fig. 5 ). This statement is, in part, contingent upon the Seychelles specimen being the same species as the types from the Chagos Archipelago. We are unaware of any genetic samples of the T. emeryi complex from anywhere in the Indian Ocean. Other specimens in the T. emeryi complex from the western Pacific also lack the yellow bars and spots on the head and body, and lack the elongate second spine of the first dorsal fin.

Discussion. Three specimens, one from each of the three localities listed under “Distribution”, were available for COI analysis ( Fig. 6 ). The variation between these samples was a little less than 1% of the base pairs of that gene. Trimma wangunui is phenetically closest to two haplogroups currently identified as T. pajama Winterbottom et al., 2014a , which latter pair are separated by 15.5% of the COI base pairs. These two groups ( T. wangunui vs. the two T. pajama haplogroups) are separated by a minimum of about 18.2%. Together, this group is separated from four distinct haplogroups, all currently (and probably incorrectly) identified as T. emeryi (Groups 2 through 5 in Fig. 6 ), by a minimum of 17.3% of the COI gene. An additional two haplogroups ( T. emeryi Group 1 and T. emeryi cf) are slightly further removed from T. wangunui at a minimum of 19.5%. Clearly this whole assembly is badly in need of an in-depth revision of the morphology and the colour patterns to see if it can be determined how many species are actually present.

Figures

FIGURE 1. Left lateral views of freshly collected Trimma wangunui. A: 20.6mm SL male paratype, ROM 108312, Papua New Guinea, SW of Nuakata I.; B: 14.7 female paratype, ROM 101358, Timor-Leste, Atauro I. (M.V. Erdmann).

FIGURE 2. Ventral view of pelvic fins of T. wangunui, ROM 108308, female holotype, 20.8 mm SL. Stained with cyanine blue (R. Winterbottom).

FIGURE 3. Left lateral (A) and dorsal (B) views of head papillae of Trimma wangunui, ROM 108308, female holotype, 20.8 mm SL. Specimen stained with cyanine blue. Papillae in a given row connected by dashed yellow lines (R. Winterbottom).

FIGURE 4. Left lateral view of anterior half of body of preserved Trimma wangunui, ROM 108308, female holotype, 20.8 mm SL (R. Winterbottom).

FIGURE 5. A: Trimma emeryi (cf), live, D’Arros I., Seychelles (Ryan Daly). B: Freshly collected specimen of T. emeryi, 17.9 mm SL female paratype, Peros Banhos Atoll, Chagos Archipelago, ROM 40317 (R Winterbottom).

FIGURE 6. Trimma haplogroups associated with T. wangunui from a Neighbour Joining Network derived from a BOLD analysis of the COI gene with 835 samples (R. Winterbottom).