Antigonia emanuela Prokofiev & Psomadakis & Gon 2020, new species

Antigonia emanuela, new species

(New English name: Emanuela’s boarfish)

(Figs. 1, 2, Table 1)

Holotype. SAIAB 203818, 60.3 mm SL (Figs. 1A, 1B), off Ayeyarwady Delta, Myanmar, Andaman Sea, Indian Ocean, 13°3.21’ N, 96°41.62’ E, R/V Dr Fridtjof Nansen station 123, 121– 129 m, P.N. Psomadakis, 21 May 2015.

Paratype. SAIAB 207256, 66.4 mm SL (Fig. 1C), off Ayeyarwady Delta, Myanmar, Andaman Sea, Indian Ocean, 12°22.31’ N, 97°12.44’ E, R / V Dr Fridtjof Nansen station 119, 99– 100 m, P.N. Psomadakis, 21 September 2018.

Note: The right pectoral fin of both type specimens is damaged. The whole fin of the paratype and part of it in the holotype were removed for genetic tissue samples.

Diagnosis. A species of Antigonia unique within the genus in the following character combination: 9 dorsal-fin spines, 13 pectoral-fin rays, deeply rhomboid body with greatest depth 113.8–118.8% SL, premaxilla strongly bent in middle, scales with deep apical crest armed with numerous spines arranged in several rows distributed in almost all lateral surface of crest, with bright-yellow soft dorsal, anal and caudal fins in life.

Description. Counts and proportional measurements are given in Table 1. Data in parentheses are of the paratype. Body deeply rhomboidal, its greatest depth clearly exceeds SL, 0.8 in or 118.8 % SL (0.9 and 113.8, respectively). Dorsal contour of body forming an almost right angle at dorsal-fin origin, strongly concave above the eye, shallowly concave and very steeply rising between tip of supraoccipital crest and dorsal-fin origin. Ventral contour of body rounded. Posterodorsal and posteroventral profiles of body very weakly and almost equally convex. Head small, 2.6 (2.5) in SL, horizontal eye diameter 2.8 (3.1) in head length, snout 1.2 (1.05) in eye diameter. Mouth gape almost horizontal. Lips somewhat thickened; alveolar ramus of premaxilla bent at almost right angle, its descending portion having a convex ventral margin, tapering toward a bluntly pointed tip. Posteroventral angle of maxilla somewhat extended anteroventrally (Fig. 1D). Jaw teeth minute, in two series at symphysis, tapering to a single series laterally in both jaws. Upper jaw length 1.4 (1.3) in horizontal diameter of eye. Ventral margin of lachrymal with 10–12 (11) short, pointed spines. Retroarticular with 1 or 2 small, blunt spines. Gill rakers slender, wider at base, about one third of gill filaments length, with series of short thin spines along inner edge. Third dorsal-fin spine longest. The tips of some dorsal-fin spines are broken in both specimens (3 rd– 6 th in the holotype and 3 rd– 7 th in the paratype). In the holotype the membrane between 3 rd and 4 th and between 4 th and 5 th dorsal-fin spines extends as two elongated skinny filaments (partly damaged). The paratype has only one such extension, between 3 rd and 4 th dorsalfin spines (Fig. 1C). Pelvic-fin spine inserted on vertical through third dorsal-fin spine. Anal-fin origin positioned on vertical through last dorsal-fin spine. Sixth interneural space vacant.

Scales above anal-fin base with deep apical crest (2.4–2.8 of scale horizontal length, measured in 3 scales); crest’s lateral surface densely covered with numerous spines arranged in about 10 more or less irregular transverse rows; lateral surface of scales with 10–12 (counted in 3 scales) moderately long and sharply pointed ctenii, longest about 1.6 in crest depth (Fig. 2).

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Colour in life. Pink, silvery on cheeks, opercle, breast and belly; bases of soft dorsal and anal fins, and caudal peduncle reddish; somewhat diffuse transverse band from dorsal fin, behind pectoral-fin base to pelvic fin, becoming indistinct ventrally; diffuse reddish patches between origins of soft dorsal and anal fins. Narrow reddish orange stripe from eye to ventral margin of breast, arching posteriorly along ventral edge of body to pelvic-fin base. Soft dorsal, anal and caudal fins bright-yellow; pectoral fin transparent; spinous portion of dorsal fin and pelvic fin (except spine and outermost soft ray) reddish; apex of spiny dorsal-fin with 1–2 red skinny pennants. Iris of eye yellow (Figs. 1A, 1C).

Colour in alcohol. Body pale brown to creamy white, darker brown internally above eye, and around abdominal cavity and opercle, both of which exhibit silvery areas externally. Spiny dorsal fin and pelvic fins with black dots on membrane and may appear dusky; other fins pale.

Distribution. Antigonia emanuela is currently known only from the type locality, off Myanmar’s Ayeyarwady Delta, in the Andaman Sea. It was collected at a depth range of 99– 129 m.

Etymology. The species epithet honours Ms Emanuela D’Antoni, FAO’s scientific illustrator—in recognition of her valuable contribution to our knowledge of the world’s aquatic biodiversity through the production of more than 30.000 drawings of species included in FAO’s national, regional and global species identification tools for fisheries purposes. It is treated as a noun in apposition.