Mistaken Pygmy Goby,

Description
Dorsal spines (total): 7; Dorsal soft rays (total): 9; Anal spines: 1; Anal soft rays: 8-9; Pectoral fin rays: 17-19; Gill rakers: 3-5 + 13-15 = 17-19; Lateral line scales: 23-24. Predorsal scales present, 8-9 scales in predorsal midline; Scales absent from the cheeks and opercle; Second and third dorsal-fin spines elongate; Moderate interorbital and postorbital trenches; Opercular scales absent. Pectoral fin with with 5-10 branched rays in the middle of the fin, an unbranched 5th pelvic-fin ray that is 51-64 % the length of 4th ray; Second dorsal-fin spine short, reaching to about base of the first ray of the second dorsal fin when abducted; 6 papillae in row c below the eye; Bony interorbital U-shaped with a narrow slit-like postorbital trench which ends at the posteriormost papilla in row p. Max. length: 2.5 cm SL. Depth range: 12 - 110 m.

Color
Snout, jaws and cheeks reddish with diffuse yellow bars from anterior margin of eye to premaxilla one third of its length from symphysis, from anteroventral eye to distal tip of premaxilla, below posterior margin of pupil across cheek, and over posterior margin of vertical limb of preopercle. Posterodorsal cheek, operculum and suboperculum with numerous dark melanophores on red to yellowish background. Pectoral fin base yellowish brown and more or less uniformly sprinkled with brown melanophores. Iris red, with two onequarter pupil-diameter yellow spots aligned diagonally across top of pupil, and two more across ventral portion of iris, posteroventral of these spots twice size of other three. Body mostly yellow, with margins of scales heavily invested with melanophores, especially on nape and anterodorsal part of trunk, centres of scales with scattered brown melanophores. Scale rows immediately above and below midlateral scales lighter, gradually merging with remainder of body colour anteriorly above anal fin base to give impression of three yellow stripes along posterior half of body, one dorsal, one along middle and one ventral. One-quarter pupil diameter dark basal stripe, followed by a similar yellow stripe in dorsal fins, remainder of fin membranes with faint yellow wash, fin rays reddishbrown; Anal fin similar but yellow stripe less well defined and yellow wash more intense and filling most of rest of fin. Caudal fin yellow, fading distally, middle rays tinged with black at tips. Pelvic fins yellow, pectoral fin membranes hyaline, rays reddish.

Etymology
Trimma: from Greek, trimma, -atos = something crushed.
harmatium: from Greek, hamartia = a mistake or error in judgment. It's an allusion to the author’s error in not recognizing the differences between this species and Trimma preclarum when describing the latter. The term encompasses “wrongdoings” which may be either accidental or deliberate. 
Original description: Trimma hamartium Winterbottom, 2018 - Type locality: Hatohobei State, Helen Reef, outer reef on west side, north of channel but south of large wreck, southwest islands of Palau, 2.91223°N, 131.7443°E, depth 23-34 meters.

Distribution
Western Pacific: eastern Indonesia east to Palau, Kiribati, Fiji and Niue, south to Great Barrier Reef (Queensland, Australia), New Caledonia and Solomon Islands.

Biology
Inhabits reef drop-offs and walls with small caves, and rubble areas.

Similar species
Trimma preclarum (Winterbottom, 2006) - Reported from Western Pacific: Philippines, Raja Ampat (West Papua, Indonesia) and Papua New Guinea east to Saipan and Fiji, south to northern Australia and Solomon Islands. Predorsal midline fully scaled, no naked area in front of first dorsal-fin spine; 19 or fewer total gill rakers; Body without a red lateral stripe; Iris with purple to red diagonal stripe across middle, a band across top of eye, and a spot above middle of cheek.

Last update: 27, May 2022