Hypselodoris bertschi Gosliner & R. F. Johnson, 1999

Description

A small to medium-sized Hypselodoris, 10–35 mm in length. The living animals are translucent white. The notum has elongate purplish dashes arranged in 4–7 linear rows. Between these are faint opaque white longitudinal lines. An orange band is present along the margin of the notum and a purple band runs along the margin of the foot. The rhinophores are white with a single orange medial band. Behind the rhinophores are two patches of lighter, more translucent pigment through which the eyes are visible. The nine unipinnate gills are white with an orange rachis.
The mantle glands are all relatively small and distributed uniformly with the exception of their absence on the anterior margin of the head. The radular formula in two specimens is 37×22.0.22 and 37×21.0.21, lacking rachidian teeth. The jaw rodlets are undivided, circular in cross-section and lack lateral flanges. The inner lateral teeth have a single large denticle on the inner side of the large bifid cusps. Most of the lateral teeth, including the middle laterals, lack denticles, with the exception of the outermost 2–4 teeth, which have 2–5 rounded denticles on the outside of the bifid cusps. The species is unique in having a greatly enlarged penial sac and a receptaculum seminis that enters the vagina near the base of the bursa copulatrix; in the candidate sister species H. kanga and H. nigrostriata the penial sac is narrow and the receptaculum enters the middle of the vagina.

Distribution

Endemic to the central Pacific, known from Kauai, Oahu, Maui and Hawaii in the Hawaiian Islands. Type locality: Ahukini Reef, Kauai, Hawaiian Islands (10 m depth).

Etymology

The species is named in honour of Hans Bertsch, who has advanced our knowledge of chromodorid species, especially those known from the Hawaiian Islands.

Remarks

Described in a 1999 revision. The new name resolves a long-standing nomenclatural confusion that began with Doris prismatica var. lineata Pease, 1860, later corrected to Dorisprismatica lineata Pease, 1864, which is likely a junior subjective homonym of Doris lineata Eydoux & Souleyet, 1852, itself a junior objective homonym of Doris lineata Brocchi, 1819. Because none of these names are available, Hawaiian material was renamed H. bertschi. The Eydoux & Souleyet species superficially resembles H. maridadilus, H. whitei or H. emma, but the identification is not conclusive.
H. bertschi is superficially similar but phylogenetically distant from other species with opaque white longitudinal lines, including the sympatric H. insulana and H. andersoni, and the allopatric H. rudmani, H. maculosa, H. capensis and H. carnea. In the consensus tree of a 1999 revision, H. bertschi is the sister to the clade containing H. kanga Rudman, 1977 and H. nigrostriata (Eliot, 1904), although the support is weak. H. bertschi has an orange band around the mantle margin while the candidate sister H. rudmani has a purple band.

---

References

• Hypselodoris bertschi sp. nov., Gosliner T.M. & Johnson R.F. (1999). Phylogeny of Hypselodoris (Nudibranchia: Chromodorididae) with a review of the monophyletic clade of Indo-Pacific species, including descriptions of twelve new species. Zoological Journal of the Linnean Society. 125: 1-114. https://doi.org/10.1111/j.1096-3642.1999.tb00585.x
• Hypselodoris bertschi, Johnson R.F. & Gosliner T.M. (2012). Traditional taxonomic groupings mask evolutionary history: a molecular phylogeny and new classification of the chromodorid nudibranchs. PLoS ONE 7(4): e33479.
• Hypselodoris bertschi,, Terrence Gosliner, Ángel Valdés and David Behrens. (2015). Nudibranch and Sea Slug Identification Indo-Pacific. New World Pubns Inc.