Aplysia norfolkensis G. B. Sowerby II, 1869

Nimbs, Matt J., 2021, Designation of a Neotype for the Dwarf Sea Hare Aplysia concava G. B. Sowerby I, 1833, and a Review of the Status of Aplysia norfolkensis G. B. Sowerby II, 1869 (Mollusca: Heterobranchia), Records of the Australian Museum (Rec. Aust. Mus.) 73 (5), pp. 147-151 : 149-151

Aplysia norfolkensis G. B. Sowerby II, 1869

G. B. Sowerby II, 1869, p. 216, pl. 10, fig. 42A–B; type locality “ Norfolk Island, New South Wales” [but later determined to be Port Jackson (= Sydney Harbour), see text];— Pilsbry, 1895, vol. 16, p. 100.

Tethys norfolkensis .— Hedley, 1906, p. 536, pl. XXXIII, figs 33, 34;— Singleton, 1937, p. 296.

Although Sowerby II lists the type locality for A. norfolkensis as “ Norfolk Island, New South Wales”, later authors assert that the type specimen was collected by John Brazier (Australian Museum) who then supplied the shell to Sowerby ( Burn, 2019; Hedley, 1906). According to Hedley (1906), Brazier’s specimens were collected from Sydney Harbour, NSW.

Sowerby’s original description, as with many 19th century sea hare descriptions, was based solely on a shell. The shell illustrated by Sowerby ( Fig. 2 ), was described as exhibiting an “ … auricle produced by the reflected dorsal margin [which] is more expanded in Aplysia concava than in this similarly shaped but differently coloured shell ” ( Sowerby II, 1869, p. 216). Later, however, Pilsbry (1895) suggested that A. norfolkensis was probably synonymous with A. concava . Hedley described and figured a living specimen of A. norfolkensis ( Hedley, 1906; pl. xxxiii, figs 33, 34) and provided a description and drawings of the mantle characteristics which are consistent with those found in A. concava ( Nimbs & Wilson, 2021) .

A single shell of A. norfolkensis collected by Brazier, from Bradleys Head, Port Jackson, Sydney, NSW, Australia on 25 June 1892 was examined and photographed as part of the present study ( Fig. 3A, B ). The morphology of this shell agrees with Sowerby’s original painting of A. norfolkensis . Additionally, this distinctive, concave shell is consistent with that found in A. concava ( Nimbs & Wilson, 2021) . Consequently, Aplysia norfolkensis G. B. Sowerby II, 1869 , is herein regarded as a junior synonym of Aplysia concava G. B. Sowerby I, 1833 .

ACKNOWLEDGEMENTS. Gratitude is extended to Mandy Reid of the Australian Museum, Sydney, Steve Smith and staff from the National Marine Science Centre, Southern Cross University and Bob Burn from Museum Victoria .

Figures

Figure 2. Original descriptions and figure illustrations of shells for Aplysia concava G. B. Sowerby I, 1833: vol. 2, p. 243, pl. 235, figs 24a,b; and Aplysia norfolkensis G. B. Sowerby II, 1869: vol. 17, p. 216, pl. 10, figs 42a,b. Sourced from Biodiversity Heritage Library, (see Sowerby I, 1833; Sowerby II, 1869).

Figure 3. Light microscope image of Aplysia norfolkensis shell, (a) dorsal view, (b) ventral view, specimen AMS C.55733, collected by Brazier, J., 25 June 1892, Bradleys Head, Port Jackson, Sydney, NSW, Australia. Photograph: M. Nimbs.