Halgerda Bergh, 1880

Fahey, Shireen J. & Gosliner, Terrence M., 2000, New records of Halgerda Bergh, 1880 (Opisthobranchia, Nudibranchia) from the deep western Pacific Ocean, with descriptions of four new species, Zoosystema 22 (3), pp. 471-498 : 473

Genus Halgerda Bergh, 1880

TYPE SPECIES. — By monotypy: Halgerda formosa Bergh, 1880 .

REMARKS

Gosliner & Fahey (1998) provide a list of characters thought to be consistent within the genus Halgerda . This list was compiled from existing literature (Rudman 1978; Carlson & Hoff 1993; Willan & Brodie 1989) and from examination by the authors of specimens of Halgerda . The list included the following characters: a smooth, gelatinous, yet firm body, a large gill that is sparsely pinnate, the openings to the rhinophore and gill pockets are smooth, the radular sac is elongate and curved, and the rhinophoral stalks are long relative to the club. Since the 1998 publication, additional work by the authors and by other workers with additional members of the genus has provided further insight to these characters. For example, rather than the typical elongate radular sac present in more derived members of the genus, the radular sac of Halgerda dalanghita Fahey & Gosliner, 1999 , a basal member of the clade, is short (Fahey & Gosliner 1999a). In addition, the phylogeny of Halgerda proposed by Fahey & Gosliner (1999b) suggests that the following six additional characters are shared by all members of the genus: the presence of dorsal ridges, ridge color that is different from the general body color; that is, being either orange/yellow or white, white rhinophore bulb color, the presence of gill glands, a rectangular radula shape, and a two-part prostate that is well-differentiated (except for the basal species, H. dalanghita ). All animals examined for the present study share these six recently described characters along with the previously identified five characters.