On the identity of the dorid nudibranch Homoiodoris novaezelandiae Bergh, 1904 (Gastropoda: Opisthobranchia)

Abstract

The New Zealand dorid nudibranch Homoiodoris novaezelandiae Bergh, 1904 (originally spelt Homoiod. Nov. Zealandiae) has been rediscovered and the recently collected specimens have provided an amended and expanded description of the species. Homoiodoris novaezelandiae is wrongly named generically—it has no vaginal plates diagnostic of the genus Homoiodoris Bergh, 1881; instead it possesses two accessory reproductive glands each opening through a straight, slightly tapered, hollow stylet and an acrembolic penis armed with spines, characteristics which place it closest to Dystylodoris Odhner (in Franc, 1968). However, as using Dystylodoris is questionable this genus is set aside for the present in the generic renaming of the New Zealand species. Homoiodoris novaezelandiae is re-assigned to the next closest genus, Hoplodoris Bergh, 1880, and compared with the two congeners, Hoplodoris nodulosa (Angas, 1864) and the type H. desmoparypha Bergh, 1880. Presently it is difficult to separate H. novaezelandiae from the other two species on externals, these being very similar in H. nodulosa and inadequately described for H. desmoparypha. The accessory reproductive gland provides the best characteristic for separation, Hoplodoris novaezelandiae having two glands, the other two species one. Hoplodoris desmoparypha is further distinguished by this gland being spherical and the stylet curved, greatly tapered and partly calcified—in this same species the penial spines are calcified too and the vagina lined with a strong cuticle.

Keywords :

• Mollusca
• Opisthobranchia
• Doridacea
• Homoiodoris novaezelandiae
• generic transfer
• redescription
• new records