Chromis hangganan, Gabriela Arango, B., T. Pinheiro, Hudson, Rocha, Claudia, D. Greene, Brian, L. Pyle, Richard, M. Copus, Joshua, Shepherd, Bart & A. Rocha, Luiz, 2019

Gabriela Arango, B., T. Pinheiro, Hudson, Rocha, Claudia, D. Greene, Brian, L. Pyle, Richard, M. Copus, Joshua, Shepherd, Bart & A. Rocha, Luiz, 2019, Three new species of Chromis (Teleostei, Pomacentridae) from mesophotic coral ecosystems of the Philippines, ZooKeys 835, pp. 1-15 : 3-6

Chromis hangganan sp. n. Figure 2a, b, Table 1

Type material.

Holotype: PNM 15358 (field code: HTP 352). 57.8 mm SL, GenBank MH170475, Lubang, Philippines. 13°45'44.71"N, 120°07'38.31"E, 130 m, RL Pyle and BD Greene, 16 May 2014 (Figure 2a, b). Paratype: CAS 243205 (field code: HTP 355). 47.9 mm SL, GenBank MH170476, Lubang, Philippines. 13°45'44.71"N, 120°07'38.31"E, 130 m, RL Pyle and BD Greene, 16 May 2014.

Diagnosis.

The following combination of characters distinguishes Chromis hangganan sp. n. from all of its congeners: dorsal-fin rays XIII, 10-12; anal-fin rays II,11-12; pectoral-fin rays 18; procurrent caudal-fin rays 3; tubed lateral-line scales 16; gill rakers 7+16-19 (total 23-26); body depth 1.9-2.0 in SL; color of adults when fresh yellowish with dark black margins on dorsal and anal fins.

Description.

Dorsal-fin rays XIII, 10 (paratype XIII, 12); anal-fin rays II,11 (paratype II,12); all dorsal and anal-fin rays have branched tips; pectoral-fin rays 18, the upper and lowermost unbranched; pelvic-fin rays I,5; principal caudal-fin rays 8+7=15; upper and lower procurrent caudal-fin rays 3; upper and lower rudimentary (spiniform) caudal-fin rays 2 and 1 respectively (paratype 2 and 2); tubed lateral-line scales 16|16; posterior midlateral scales with a pore 9|10 (paratype 10|10); scales above dorsal fin to origin of dorsal fin 3|3 (paratype 2|3); scales below lateral line to origin of anal fin 8|8; circumpeduncular scales 11 (11); gill rakers 7+19=26 (paratype 7+16= 23); vertebrae 25 (11 precaudal + 14 caudal).

Body depth 1.9 (paratype 2.0) in SL, and width 3.0 (3.1) in body depth; head length 3.0 (3.2) in SL; snout very short, length 5.4 (7.1) in head length; orbit diameter 2.8 (2.7) in head length; interorbital width 2.9 (3.2) in head length; caudal-peduncle depth 2.3 (2.1) in head length; caudal-peduncle length 2.5 (2.5) in head length.

Mouth terminal, small, oblique, upper jaw angle of 35°; maxilla posterior edge beyond anterior edge of eye, upper jaw length 3.3 (3.3) in head length; gill rakers long and slender, longest on lower limb near angle about the length of longest gill filaments; nostril without fleshy rim, located above level of middle of pupil.

Opercle ending posteriorly in internal spine, obscured by scales; preopercle margin smooth, posterior margin extending on the top edge of pupil; suborbital with free lower margin extending nearly to a vertical at posterior edge of pupil. Scales finely ctenoid; anterior lateral line ending beneath the 13th dorsal-fin spine; head scaled except lips, tip of snout, and a narrow zone from orbit to edge of snout containing nostrils; scaly sheath at base of dorsal and anal fins; column of scales on membranes, spines and rays of dorsal and anal fins, progressively smaller distally; small scales on caudal fin extending slightly more than two-thirds distance to posterior margin; small scales on basal one-fifth of pectoral fins; median scaly process extending posteriorly from between base of pelvic fins, its length slightly more than half that of pelvic spine; axillary scale above base of pelvic spine slightly more than one-fifth length of spine.

Color.

Images of fresh specimens not available. Our field notes characterize fresh specimens of Chromis hangganan sp. n. as having a yellowish body color, with light yellow caudal peduncle and caudal fin. Body overall brown, darker dorsally. Black outer margins of the spinous dorsal and anal fins, and yellowish dorsal rays. Ventral margin of body and anal fin spines also black. Anal-fin rays yellowish. Anterior (mouth and snout) and dorsal (nape) portions of the head and orbit dark brown. Ventral portion of head light brown. Black dot on dorsal 1/5 of pectoral fin base and axilla.

Etymology.

The name hangganan means border in Tagalog, in reference to the black margins of the dorsal and anal fins. To be treated as a noun in apposition.

Distribution and habitat. Lubang Island, Philippines. Despite dives in several sites of the Verde Island Passage (VIP), Philippines, this species has not been collected outside of Lubang. The Lubang Island environment differs from the other survey sites in the Verde Island Passage by having more exposed and clearer oceanic waters, probably due to its proximity to the South China Sea. The species was recorded on MCEs at depths of 90-130 m.