Enneapterygius sericus, a new species of triplefin (Perciformes: Tripterygiidae) from the western Pacific Ocean

Abstract

A new triplefin, Enneapterygius sericus sp. nov. (Perciformes: Tripterygiidae), is described from 51 specimens from the Ryukyu Islands, Taiwan, Indonesia, Australia, and the Solomon Islands. The new species is characterized by the following combination of characters: 9–11 (modally 10) third dorsal-fin rays; ii–v (iv) + 3–6 (4) + iv–viii (vii) = 13–16 (15) pectoral-fin rays; 17–21 (19) anal-fin rays; 15–18 (16) pored lateral-line scales; 32–37 (36) scale rows in longitudinal series; 8–12 (10 or 11) circumpeduncular scales; single transverse scale row between posteriormost pored scale and anteriormost notched scale; mandibular-pore formula usually 3 + 1 + 3; 1st spine of first dorsal fin shorter than that of 2nd dorsal fin, its length 5.5–10.2% (mean 8.2%) of standard length; orbital tentacle short, slender and pointed, its length shorter than nasal tentacle; body generally semi-transparent white with reddish pigmentation; dorsal surface of head with brownish blotches; and head, pectoral-fin base, and abdomen black in nuptial males. Enneapterygius sericus sp. nov. is most similar to Enneapterygius nanus (Schultz 1960), but differs from the latter as follows: 12–14 (modally 13) second dorsal-fin spines [vs. 12 or 13 (12) in E. nanus]; 3 or 3½ scales below 1st notched lateral-line scale [vs. 2 or 2½ (2)]; orbital tentacle slender and pointed (vs. small, leaf-shaped, the edge slightly rounded); dorsal head surface with brownish blotches (vs. unpigmented); lower half of head, opercle, pectoral-fin base, and base of 8 lowermost pectoral-fin rays black on lateral surface; undersurface of head, including pelvic-fin base, and anterior part of abdomen (sometimes extending to anus) black (vs. pectoral-fin base without black pigmentation, black region on ventral body surface reaching or slightly beyond pelvic-fin base). Enneapterygius sericus sp. nov. usually occurs on exposed shallow rocky reefs [in depths less than 5 m off Yaku-shima Island (type locality)]. Spawning has been observed at Yaku-shima Island from the end of February to April.