Trypauchen

Trypauchen is unique within the Amblyopinae in having the following combination of characters: 1) typically four, rarely three, anal-fin pterygiophores anterior to the first hemal spine; 2) pelvic fins small, united, and funnel-shaped with a well-developed interradial membrane; and 3) abdomen scaled.

Total dorsal-fin elements 46–58; first dorsal fin with six flexible spines (one specimen of T. vagina with five); all second dorsal-fin rays segmented and branched; dorsal-fin base long and broadly joined with caudal fin. Total anal-fin elements 39–50, all elements segmented and branched; anal-fin height less than second dorsal-fin height; anal-fin membrane broadly joined with caudal fin. Pectoral fin with 15–20 rays, crescent-shaped or falcate with upper rays longer than lower ones; all pectoral-fin rays segmented and branched distally. Pelvic-fin rays I,4 or I,5; broad frenum present; medial rays longest and completely united by interradial membrane; pelvic fins forming a small funnel that is slightly pointed posteriorly. Caudal fin with 17 segmented rays including 8+7 branched rays and an upper and lower simple ray; unsegmented procurrent rays 4, 2 dorsally and 2 ventrally. Scales cycloid, present only on body, largest posteriorly, scales overlapping in caudal peduncle area. Longitudinal scale count 59–98, difficult to count with accuracy. Eye rudimentary and covered by skin in orbital depression, lens slightly larger than length of posterior naris. Posterior naris located on dorsoanterior rim of orbit; anterior naris at tip of small tube-like flap that slightly overhangs upper jaw. Chin, snout, and interorbital area with thickened flesh, which likely aids in burrow construction.

Trypauchen is unique within the Amblyopinae in having the following combination of characters: 1) typically four, rarely three, anal-fin pterygiophores anterior to the first hemal spine; 2) pelvic fins small, united, and funnel-shaped with a well-developed interradial membrane; and 3) abdomen scaled. Trypauchen comprises two species: T. pelaeos, known from Myanmar, Malaysia, Thailand, Vietnam, and China; and T. vagina, distributed from Israel, Kuwait, along the coasts of India, ranging eastward to the Philippines, Taiwan, and China.