Akko brevis (Gunther 1864)

photo by Ross Robertson - Panama

IDENTIFICATION

Head Pores - Cephalic head pores B', G' generally present, very small; no preopercle pores present

Scales - 53-60 scales in the lateral series, overlapping on the caudal peduncle

Fins - D1 - VII, D2-15, anal - 15, pectoral 19-20(19-21), caudal - 17 segmented rays, median fins are continuous

Head - Mouth large, capable of expanding to a complete circle equal to the body diameter in live specimens; oriented at an angle of 50° to the horizontal; upper jaw slightly protrusible; no rostral frenum. An oral velum is present with dorsal and ventral projections. Upper and lower lips possess 10-15 papillae along the lateral upper edges. The anterior nostril is composed internally of a thickened, U-shaped, fleshy tube. The posterior nostril consists of a short tube or raised rim with no muscular development. The gill opening extends from the fourth upper pectoral ray to above the pelvic-fin base with a flap, supported by the second branchiostegal ray, extending back to the ventral-most pectoral ray. No pseudobranch present. The eye is small, covered with skin, slightly recessed, and has a large lens.

Papillae - Horizontal row b has an elongate anterior extension well in front of the eye; row d is complete, not divided into two sections, and row ot extends ventrally onto the branchiostegals, ending just past the second branchiostegal ray. The first vertical papillae row is complete, extending from the eye to near row d. Additional vertical rows are divided by row b, with two rows above and four rows below row b. Only the last vertical row below row b extends below the level of row d. Dorsal rows X1 and X2 are continuous, or nearly so, as is row n.

Color - The general body color is whitish with a light pink overtone in live specimens. The upper body has numerous densely packed melanophores, the pigment becoming less dense ventrally and ending at the lateral midline. The belly is whitish from the ventral surface to the lateral midline. The head and upper lip have densely packed small melanophores dorsally that become less concentrated ventrally and terminate at the ventral midline. The pectoral, pelvic, and anal fins are transparent. The caudal fin is black except for the midbasal area, which is whitish with a few scattered melanophores. The dorsal fins have scattered melanophores restricted to the membranes between the fin elements that become more concentrated towards the margin of the fin. Neither males nor females possess any genital pigmentation.

Distribution - Eastern Pacific, El Salvador to Peru

Habitat - Black mud

Notes -