New records of Halgerda Bergh, 1880 (Opisthobranchia, Nudibranchia) from the deep western Pacific Ocean, with descriptions of four new species

Four new species of Halgerda from the deep western Pacific Ocean are described. Halgerda fibra n. sp. was found in the Philippines at depths near 90 m and is also recorded from the New Caledonia region in 90-400 m. The new species differs from other Halgerda in its reproductive morphology. The ampulla is larger and more coiled than other Halgerda and the vagina is also much larger and more bulbous than other members of the genus. Halgerda abyssicola n. sp. was found near Vanuatu at depths of 207-280 m and from the Coral Sea in 385-420 m. Its reproductive morphology is unusual for a species of Halgerda in that the penis and vagina are both extremely large and bulbous. Halgerda azteca n. sp. was found near Norfolk Ridge, south of New Caledonia at depths from 230-367 m. Its reproductive morphology differs from other Halgerda species primarily due to its long, coiled ejaculatory duct and prominent vaginal sphincter. Halgerda orstomi n. sp. was found near Vanuatu at depths between 160-251 m; from the Philippines at 92-95 m and from New Caledonia at 120 m. Halgerda orstomi has an unusual vaginal sphincter and bulbous vagina which distinguishes it from other Halgerda species. The ranges and depths of three additional, previously described Halgerda species: H. brunneomaculata Carlson & Hoff, 1993, H. carlsoni Rudman, 1978 and H. dalanghita Fahey & Gosliner, 1999 are also extended.