Pteraeolidia semperi (Bergh, 1870)

Type locality: Philippines, Pacific Ocean

(Figs 3 A-C, 4 A, C, E, 5 A, C, E)

Flabellina semperi Bergh, 1870: 18–30

Pteraeolidia semperi (Bergh, 1870) Bergh, 1875: 652; Eliot, 1903: 255; Bergh, 1905; Eliot in Hornell 1909: 144; Eliot, 1913: 44; Baba, 1949: 182–183; Risbec, 1953: 161–163; Risbec, 1956: 31; Marcus & Marcus, 1960: 921–922; E. Marcus, 1965: 280

F. scolopendrella Risbec 1928: 259–260. Type locality: New Caledonia, Pacific Ocean.

misidentified as Pteraeolidia ianthina (Angas, 1864) Ev. Marcus & E. Marcus 1970:211; Gosliner, 1980:60; Johnson & Boucher 1983:34.

Material examined: (also Table 1): One specimen UF 400267, French Polynesia, Tuamotu Islands, Aratika Atoll (15°29′36.07″S, 145°26′22.74″W), 5 m, coll. Machel Malay, 5 June 2006; one specimen FL MBIO.41683, French Polynesia, Society Islands, Moorea, W side Opunohu Bay (17°49′41 S, 149°86′20 W), 10–20 m, coll. Greg Rouse & Fred Pleijel, 10 Dec 2010; one specimen AMS C.474026, Australia, Great Barrier Reef, Heron Island, NE Bernies Bay (23°25′58.74″S, 151°57′18.34″E), 0–1 m, coll. Daniel Jackson, 16 Jan 2003; one specimen, lost, Australia, Great Barrier Reef, Lizard Island, Casuarina Beach (14°41′22.74″S, 145°27′58.07″E), coll. Sabrina Bleidissel, 2008; one specimen, lost, Australia, Great Barrier Reef, Lizard Island, Loomis Reef (14°41′00.43″S, 145°26′57.92″E), coll. Sabrina Bleidissel, 2008; one specimen AMS C.474022, Papua New Guinea, Louisiade Archipelago, NW Misima Island, nr Gulewa (10°37′49.34″S, 152°44′41.88″E), 2.5 m, coll. Nerida Wilson & Greg Rouse, 14 Aug 2006; one specimen AMS C.474021, Indonesia, SE Sulawesi, Tukangbesi Archipelago, Kaledupa, Sampela Buoy 2 (5°28′46.14″S, 123°44′24.54″E), 6 m, coll. David Thompson & Nerida Wilson, 19 Aug 2002; one specimen AMS C.474020, Indonesia, SE Sulawesi, Tukangbesi Archipelago, Kaledupa, Sampela Buoy 2 (5°28′46.14″S, 123°44′24.54″E), 6 m, coll. Nerida Wilson, 15 Jul 2002; one specimen AMS C.474013, Indonesia, SE Sulawesi, Tukangbesi Archipelago, Hoga, Home Reef Buoy 4 (5°28′13.54″S, 123°45′24.85″E), 12 m, coll. Nerida Wilson, 4 Aug 2002; one specimen AMS C.474014, Indonesia, SE Sulawesi, Tukangbesi Archipelago, Hoga, North Wall 2 (5°27′1.09″S, 123°46′6.06″E), 19 m, coll. Nerida Wilson, 13 Sep 2002; one specimen AMS C.474016, Indonesia, SE Sulawesi, Tukangbesi Archipelago, Hoga, Coral Gardens (5°26′44.30″S, 123°45′19.33″E), 10 m, coll. David Thompson & Nerida Wilson, 15 Sep 2002; one specimen AMS C.474017, Indonesia, SE Sulawesi, Tukangbesi Archipelago, Kaledupa, Double Spur (5°27′53.03″S, 123°42′9.51″E), 8 m, coll. Coral Horn, 18 Aug 2002; one specimen AMS C.474018, Indonesia, SE Sulawesi, Tukangbesi Archipelago, Hoga, Coral Gardens (5°26′44.30″S, 123°45′19.33″E), 11 m, coll. Coral Horn, 10 Sep 2002; eight specimens AMS C 474045- C.474047, C.474171, C.474049- C.474052, Hawaiian Islands, Maui, Makena (20°39′21.24″N, 156°26′37.26″W), 18 m, coll. Pauline Fiene, Feb 2003; one specimen UF 415599, Hawaiian Islands, French Frigate Shoals (23°45′21.47″N, 166°07′35.87″W), 32 m, coll. Corey Pittman, 11 Oct 2006; three specimens AMS C.474060- C.474062, Hawaiian Islands, Oahu, wreck of the Yo-256 (21°15′38.76″N, 157°50′15.00″W), 32 m, coll. Greg Rouse, Feb 2006.

Diagnostic clade characters (which will require further delineation with broader geographic sampling): Oral tentacles with three or more purple bands, the two bands closest to the head may be very close together and partially fused (see Fig. 3). White markings on head, particularly anterior to rhinophores. Dorsal and lateral body typically show white vertical bars or spots. Cerata and body often show white, green or yellow and mottled markings. Cerata relatively short in comparison to body length. Size up to 150 mm.

Radula: Radular formula ranges from 15–36 × 0.1.0 (Bergh, 1870; Baba, 1949; Marcus & Marcus, 1960; Gosliner, 1980; Rudman, unpubl. obs.; AMS.C.131625 18(+2)x0.1.0; AMS C.96581 22(+2)x0.1.0; AMS C.129222 22(+2)x0.1.0; AMS C.152525 26(+1)x0.1.0; AMS C.152524 23(+1)x0.1.0; AMS C.99008 18x0.1.0; AMS C.129221 16(+1)x0.1.0;, Figs 4, 5). Each rachidian tooth with large median cusp. Margin of rachidian tooth with 5–12 relatively long denticles (Bergh, 1870; Eliot, 1903; Baba, 1949; Gosliner, 1980). Central rachidian tooth relatively blunt and broad with uppermost pair of denticles closely attached to central cusp (without a deep gap). Radular denticles generally arcuated towards central cusp.

Distribution: Widespread tropical Indo-Pacific. From NSW, Australia, northwards through the Great Barrier Reef, northeast to Hawaii, northwest to Japan, through the Coral Triangle, to the Red Sea, to the southerly limits of Indian Ocean reaching South Africa and Western Australia, through parts of South Australia.

Depth range: intertidal to 32 m (AMS C.128126 and C.474060 respectively).

Symbiosis: Highly efficient with long-term retention of zooxanthellae (Wägele & Johnsen, 2001; Burghardt et al., 2008). Symbionts from most areas remain untested and unknown. Specimens from Singapore and Indonesia host Symbiodinium clades C and D, although specimens from southern QLD and the Great Barrier Reef are so far only known to host clade C (Loh et al., 2006).

Remarks

Burn (1965) made P. semperi (Bergh, 1870) a subjective junior synonym of P. ianthina, notionally on the basis of priority (F. ianthina was described 6 years before F. semperi). This was followed by Marcus & Marcus (1970, Madagascar) and reluctantly, by Gosliner (1980, Hawaii). However, Bergh (1875) clearly designated P. semperi as the type by monotypy, and this cannot be ignored. Therefore Pteraeolidia semperi is recognised as the type species of Pteraeolidia. Pteraeolidia scolopendrella (Risbec, 1928) from New Caledonia is an available name that may be connected to a cryptic lineage in future studies. However, Risbec (1953) was persuaded to list P. scolopendrella as a synonym of P. semperi, and was presumably unaware of Bergh’s species at the time of describing P. scolopendrella . We adopt the conservative position of leaving P. scolopendrella in synonymy until a revision can be done examining material from type locality.

Pteraeolidia ianthina (Angas, 1864)

Type locality: Port Jackson (enclosing Sydney Harbour)

(Figs 3 D-H, 4 B,D, E, 5 B,D, E, 6, 7)

Flabellina ianthina Angas, 1864: 66–67, pl. 6, fig. 6.

Pteraeolidia ianthina (Angas, 1864) Burn, 1965: 89– 90; Rudman, 1982: 178–183

Material examined: (also Table 1): Eight specimens AMS C.474030 –AMS C.474135, Australia, Sydney, Bare Island (33°59′30.40″S, 151°13′56.67″E), 5 m, coll. William Loh & Melissa Cowlishaw, 2002; one specimen,AMS C.474137, Australia, Sydney, Clovelly, Gordons Bay (33°54′59.31″S, 151°15′49.15″E), 8 m, coll. Nerida Wilson & Lauren Hughes, 31 Jul 2011; eight specimens AMS C.474036- C.474043, Australia, Port Stephens, Nelson Bay, The Pipeline (32°43′3.64″S, 152°8′28.44″E), 5 m, coll. David and Leanne Atkinson, 20 May 2003; one specimen AMS C.474044, Australia, Eden, Chipmill Wharf (37°6′24.66″S, 149°55′37.85″E), 4 m, coll. Nerida Wilson, 3 April 2007.

Diagnostic species characters: Oral tentacles with two purple bands (see Fig. 3). No white markings on head. Lateral body with purple and brown markings, no white vertical bars or spots. Cerata do not show white markings away from tip, although entire animal may be pale in animals lacking an active zooxanthellae symbiosis. Cerata relatively long in comparison to body length. Size up to 100 mm.

Radula: Radular formula ranges from 12–27 × 0.1.0 (Angas, 1864; Rudman, 1982; Rudman, unpub. obs.; AMS C.133292 27x0.1.0; AMS C.114580 25x0.1.0;AMS C.63054 22(+2)x0.1.0; AMS C.114580 12(+2)x0.1.0; AMS C.1436 17(+4)x0.1.0, Figs 4, 5). Each rachidian tooth with large median pointed cusp. Margin of rachidian tooth with relatively long denticles. Central rachidian tooth elongated, pointed, with deep gap between central tooth and innermost pair of denticles. Radular denticles generally only slightly arcuated towards central cusp.

Distribution: Temperate eastern Australia, New South Wales, from Eden (southern NSW), northwards to the Solitary Islands, Coffs Harbour, NSW (Fig. 6).

Depth range: 4–30 m (AMS C.474044 & C,146981 respectively).

Symbiosis: Highly efficient, with long-term retention of zooxanthellae (Hoegh-Guldberg & Hinde, 1986). Specimens from NSW host Symbiodinium clades A and B (Loh et al., 2006).

Remarks

This species is easily recognisable from Angas’ drawings. The figure published with the species description (Angas, 1864) shows some minor colouration differences from the original notebook drawing, which we reproduce here (Fig. 7). The main differences are that the original publication (Angas, 1864) whitened the body colouration that is normally brown with symbionts, dorsal markings have been erased, and the colour of the cerata are violet/purple instead of blue. The notebook drawing is a much more realistic interpretation, and is worthy of circulation. It is believed that the hand-coloured drawings in his sketchbook ‘Nudibranches of Port Jackson’ were produced in approximately 1852 (http://australianmuseum.net.au/ Nudibranches-of-Port-Jackson).

Although the name has been applied widely through the Indo-Pacific, we show here that it should be restricted to animals from temperate New South Wales, Australia. The exact distributional boundaries are yet to be determined, but so far this species appears to be found only in New South Wales, Australia.