Halgerda formosa, Berg 1880
This is the type species for the genus Halgerda. It was first described by Bergh in 1880. Other authors misidentified specimens they collected as Halgerda punctata (Rudman, 1978, Gosliner, 1987 and Wells & Bryce, 1993). But recent examination of the specimens has shown that those animals were indeed H. formosa. Additional specimens have been collected and examined from Mauritius and Southern Tanzania. The distribution of Halgerda formosa is the Indian Ocean.
This species can be distinguished by its yellow-orange ridges with no tubercles, irregularly spaced dark spots on the mantle and foot, dark coloration on the rhinophores and gills and four gill branches. Many other Halgerda have six gill branches. The dark viscera can be seen through the notum. The animals are small: 7-10 mm.
Shireen J. Fahey and Terrence M. Gosliner. 1999.Description of Three New Species of Halgerda from theWestern Indian Ocean with a Redescription of Halgerda formosa Bergh, 1880. Proceedings of the California Academy of Sciences, 51(8): 365-383, 8 Figs.
Photos courtesy of Terry Gosliner
Taxonomic text courtesy of Shireen Fahey
Shireen is in the Marine Biology program and for her thesis, she is developing
the phylogeny and biogeography of the nudibranch genus Halgerda. She has
started with a set of morphological characters but intends to include
molecular and biochemical character sets.