Trimma anaima Winterbottom, 2000

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 : 8-11

Trimma anaima Winterbottom, 2000

Sharpeye Pygmygoby

Figs. 2 , 3 ; Pl. 1 A

Trimma anaima Winterbottom, 2000:58 (Anjouan Id, Comores); Hayashi & Shiratori, 2003:41 ( Japan); Allen et al., 2004:331; Anderson, 2005:104 ( Maldives); Allen & Erdmann, 2012:934 (Indo-west Pacific).

Trimma amaina (lapsus): Kuiter & Tonozuka, 2004:73 (x 2, Indonesia).

Trimma sp. 5: Kuiter, 1998:209 ( Maldives).

Trimma RW sp. 28: Winterbottom, 1990:255 (comparison with Trimmatom ).

Australian Material.Queensland: Ashmore Reef: AMS I.33728-043, 6(11–12), 11–15 m; AMS I.33736-050, (13), 20– 30 m. Near Lizard Id: WAM P.28531-010, (15), 10– 15 m. Osprey Reef: AMS I.25112-036, (14), 1– 15 m. Portlock Reef: AMS I.33751-071, (12), 5– 31 m.

Other material. See Winterbottom (2000) for a list of material examined in the original description. New material includes: Indonesia: Raja Ampat, ROM 85248, 2(11–13), 12– 26 m. New Caledonia: Loyalty Id: USNM 321802, 2, 23– 29 m. Palau: Main Ids: ROM 80303, (14), 27–42 m; ROM 80028, (12), 34–45 m; ROM 80351, 2(14–15), 73m; ROM 80395, 2(11–11), 20–27 m; ROM 80404, 2(13–14), 34–44m; ROM 80469, (12), 40– 49 m. Southwest Ids: ROM 82989, (12.0), 20–36 m; ROM 83022, (13.7), 20–31 m; ROM 83048, 2(13.6–15.5), 12–30 m; ROM 83071, (12.9), 16–28 m; ROM 83262, 8(9.8–11.7), 20–35 m; ROM 83269, 2(11.5–11.9), 22–34 m; ROM 83331, (11.8), 10–30 m; ROM 83373, 5(9.5–12.5), 23– 36 m. Philippines: Palawan, Dilumacad Id: WAM P. 32877.001, 2(19–20), 20– 30 m. Pamilacan Id: USNM 244051, 0–33.5 m. Solomons: Stewart Id: USNM 365584, 2, 0– 20 m.

Diagnosis. A species of Trimma with a bony interorbital about two-thirds pupil diameter in width and only slightly concave; no troughs or trenches in the interorbital or posterodorsal orbital regions; no scales in the predorsal midline; fifth pelvic-fin ray unbranched and 50–60% fourth ray; pectoral-fin rays unbranched; epaxialis extending anteriorly to a vertical in line with the posterior margin of the orbit; no spines of first dorsal fin elongated; body straw-yellow (translucent above midlateral septum, reddish-orange below in life) with most specimens possessing a small dark spot posterodorsally just behind the eye, four small (one-quarter pupil diameter) dark saddles in the dorsal midline at the origins of the first and second dorsal fins, the last dorsal ray and about the mid-length of the caudal peduncle.

Description. The description is based primarily on the type material from the Comores Archipelago. Dorsal fins VI + I 8, second spine longest (but not elongated), reaching posteriorly to bases of spine or first two rays of second dorsal fin when adpressed, first ray and anterior element of last ray branched or unbranched, last ray reaching posteriorly to midpeduncle in females and juveniles, to or almost to procurrent rays of caudal fin in males; anal fin I 8, condition of first and last rays as for dorsal fin; pectoral fin 15–16 (once 17, mean = 15.8), all fin rays unbranched, fin reaching posteriorly to above anterior elements of anal fin; pelvic fin I, 5, first four rays with a single sequential branch, fifth ray unbranched and 50–60% length of fourth, which reaches posteriorly to bases of first few elements of anal fin; fraenum absent, basal membrane vestigial. Lateral scales 23; transverse scales 7; two specimens (not largest) in very good condition with one or two deciduous scales on upper part of opercle (no trace of scales or scale pockets discerned in other specimens); two large vertically aligned scales on pectoral-fin base with a small third scale ventrally; 4–5 irregular rows of scales across midline anterior to pelvic fin; scales on nape, opercle (when present), pectoral base, breast and anterior midline of belly cycloid; others ctenoid; body scales extending anteriorly on either side of midline almost to eye but very deciduous and often missing (with little or no trace of scale pockets). Teeth in inner and outer rows of lower jaw and outer row of upper jaw of curved, spaced, enlarged canines separated by irregular rows of small conical teeth. Tongue narrow and pointed, about half pupil diameter in width. Gill opening to below mid-pupil; outer gill rakers on first arch 2–3 + 11–12 (mean = 2.6 + 11.7). Anterior nares in a short tube, posterior pore-like with a raised rim, nasal sac somewhat elevated, nasal apparatus confined to anterior half of snout. Bony interorbital about two-thirds pupil diameter in width, slightly concave with no interorbital or posterodorsal orbital troughs; epaxialis musculature reaching to above posterior margin of orbit. Abdominal/caudal vertebral transition type intermediate, modified Type B, with ninth abdominal vertebra lacking a 'haemal arch' (based on two cleared and stained specimens, ROM 1149CS, although there is a medial projection of left haemal arch that does not reach midline on one side of one specimen), tenth vertebra with such an arch, and first abdominal vertebra with two foraminae. As far as is known, this combination, if confirmed on more specimens, is unique within the species of Trimma .

Colour pattern. Live and freshly collected. Based on colour slides of living specimens from the Maldives, Indonesia (Pl. 1 A), Papua New Guinea and Guam, and freshly collected specimens from the Comores (13.0 mm SL male holotype, and 13.8 mm SL female), Palau ( Fig. 2 , 13.7 and 14.2 mm SL) and Fiji (13.6 mm SL). Live Maldives specimens translucent with reddish wash from below midlateral line to just above ventral midline on body (to just below orbit on head), interorbital region red which may continue posteriorly as an increasingly poorly defined mid-dorsal stripe as it grades to orange (no longer discernible posterior to origin of second dorsal fin), snout orange-red except for a white spot in anterior midline, iris ringed with red with a dorsomedial stripe of electric blue, caudal fin straw-coloured, other fins not discernible. Indonesian specimen similar, with translucent fins and white spot on snout not apparent in available image. Papua New Guinea specimen with two rows of indistinct reddish orange spots in dorsal fins, a bluish-white bar through top of iris, and iridocytes on cheek just beneath a horizontal line touching ventral margin of orbit that marks ventral extent of reddish body wash. Guam specimen with only a hint of reddish wash on lower half of body, whole fish translucent greyish, with a strong iridescent stripe just below eye. Freshly collected specimens similar (although colouration of dorsal midline cannot be seen) but distal portions of dorsal, anal and pelvic fins may be light orange or yellow, and proximal areas usually hyaline (although colour may persist to distal part of anal fin). Fijian specimen with scattering of iridocytes proximally in dorsal and anal fins.

Preserved. Plain straw coloured with a small (one-quarter pupil diameter) black spot made up of melanophores just posterodorsal to orbit (two o'clock position), and four similar-sized dark saddles across dorsum just anterior to origin of first and second dorsal fins, in gap between two dorsal fins, at base of last dorsal-fin ray, and at middle of length of caudal peduncle (all spots may be faint or absent); fins hyaline except in some specimens, where first dorsal fin may have a scattering of melanophores, especially distally. A dark line of melanophores adjacent to base of the anal-fin, continuing in midventral septum to the base of the first procurrent-fin ray.

Etymology. From the Greek 'anaimos', meaning bloodless, pallid, pale or anaemic, in allusion to the pale, almost washed-out colouration of the species. Used as a noun in apposition.

Distribution. Trimma anaima is a relatively rare species in collections, and has usually been taken in lots of one or two specimens. An exception to this is Fiji, where the ROM has lots of 6, 19 and 22 specimens from the Great Astrolabe Reef. It has been found from the Comores and Maldives (photographic record) eastward through the central Philippines and Palau (new record) to Fiji ( Fig. 3 ). There are currently no records from mainland Asia or the Pacific plate.

Comparisons. Trimma anaima is a small (maximum recorded SL = 15.3 mm) distinctive species. The relatively broad interorbital is somewhat reminiscent of the T. tevegae species group, all of which have scales in the predorsal midline and a different configuration of the abdominal/caudal vertebrae (see Introduction). At least one other species ( T. cana Winterbottom, 2004 , from the Philippines and Palau to the Marshalls Islands and Fiji) is known to have a bright white spot in the midline at the tip of the snout when alive (RW, pers.obs.); this species has red bands on the body (which disappear after preservation), an elongate second dorsal-fin spine, 9–10 dorsal- and anal-fin rays, and 16–18 pectoral-fin rays. Currently, only two specimens (from Raja Ampat, Indonesia) have been analysed for the CO1 gene. They are well separated (ca. 25%) from all other species of the genus based on the distance data.

Discussion. This species, referred to as Trimma RW sp. 28, has been suggested as the possible sister group to the genus Trimmatom on the basis of its small adult size, unbranched pectoral-fin rays, unbranched fifth pelvic-fin, and the small dark saddles over the dorsal midline ( Winterbottom, 1990). Testing of this hypothesis will have to await a detailed phylogenetic analysis of both Trimma and Trimmatom .

Figures

FIGURE 2. Trimma anaima, A: 13.7 mm SL male, ROM 83022; B: 14.0 mm SL male, ROM 80303 (note parasitic copepod attached to belly), both from Palau. Photos by R. Winterbottom.

FIGURE 3. Map of the distributions of Trimma anaima (solid circles) and T. annosum (solid triangles). A black star indicates localities at which both species occur.