TANE 25. 1979

NEW ZEALAND LOCALITY RECORDS FOR THE AEOLID (ESCHSCHOLTZ)

by R.C. Willan Department of Zoology, University of Auckland, Private Bag, Auckland

SUMMARY

Fiona pinnata (Eschscholtz 1831) is a pelagic aeolid nudibranch that lives on driftwood and floating algal masses associated with Lepas spp. bar• nacles. It can apparently feed on several species of Lepas. Its distribution is circumtropical and circumtemperate. Available records for New Zealand suggest that Fiona pinnata can be cast ashore on any of the open beaches around the coastline, providing the wind is from the right quarter.

INTRODUCTION

The finding of numerous Fiona pinnata (Fig. 1 A, B) together with Lepas testudinata Aurivillius on detached, floating plants of the laminarian kelp Durvillaea antarctica (Chamisso) Hariot off the Cavalli Islands has highlighted the need to update the New Zealand locality records for this unique aeolid. Fiona pinnata is the sole species in the monotypic family , distinguished from other aeolid groups by the possession of simple oral tentacles and rhinophores which resemble each other; the cerata are in oblique rows and, apart from the smallest cerata at the extreme out- sides of the rows, all have a membranous expansion on the inner margin, and there are no cnidosacs; the anus opens dorso-laterally; the reproductive apertures open separately; the jaws are horny and have a denticulate border; the radula is uniserial, bearing arched teeth with pectinate edges, each has a median cusp which is longer than the side cusps (Suter 1913, Pruvot-Fol 1954, MacFarland 1966). Fiona pinnata is usually creamish or buff in colour although it becomes blue when feeding on Velella velella (Linneaus) (Kropp 1931, Bayer 1963, Bennett 1966). Each ceras has a darker central area corresponding to the digestive diverticulum; the head and tentacles are white. Though not large in size, nor spectacular in colouration as aeolids go, Fiona pinnata was one of the first to be recognised and identified unequivocally. In 1775, Forskal named it Doris marinus, but that name was preoccupied by Gunnerus' usage five years earlier (Pruvot-Fol 1954). In nomenclatural terms, New Zealand will always be associated with Fiona pinnata because specimens from this country have twice been described as new species. J.C. Quoy and J.P. Gaimard (1832) named this species

141 "Eolide a longue queue (Eolidia longicauda)" and Finlay (1927) provided the Dolicheolis for this taxon. Hutton (1882) called this aeolid Aeolis plicata. None of these early authors could have realised that Fiona pinnata possesses such an enormous range throughout tropical and temperate seas.

NEW ZEALAND LOCALITY RECORDS

OPEN SEA: "Tui" Cruise Stn. AUZ 124, 33°13'S, 178°24'E—on a floating Durvillaea antarctica plant, M.C. Miller, 2 August 1962; 16km east of Cape Brett—living amongst Lepas sp. on a Japanese fish float, M.C. Miller, 30 January 1962. COAST—NORTH ISLAND: c. 30 specimens, 200m east of Nukutaunga Island, Cavalli Islands—amongst living Lepas testudinata on holdfasts of two floating Durvillaea antarctica plants, R.V. Grace, 31 December 1978; Main Beach, opposite Goat Island, Leigh—with Lepus anatifera, on drift• wood cast ashore during a storm, B.A. Foster, 2 February 1966; Piha—on a log washed up on the beach, M.C. Miller, 25 September 1965; Orua Bay, southern shore of entrance to Manukau Harbour, Auckland—one on the shell of a living Janthina globosa cast ashore during prolonged north• westerly winds, N. Douglas, 25 April 1972; Maioro Beach, south of Port Waikato—specimens found amongst Lepas sp. attached to a buoy washed ashore, N. Douglas, 1978 (Williams 1978); Waikanae Beach—on Lepas sp. attached to a drifting log, W.F. Ponder; Lyall Bay, Wellington—on holdfasts of Durvillaea sp., 16 April 1948 (National Museum); Island Bay, Wellington—on holdfasts of Durvillaea sp., cast up on the beach, May 1959 (National Museum). SOUTH ISLAND: Summer Beach, Christchurch—on holdfast of a Dur• villaea antarctica plant, washed ashore (Hutton 1882); New Brighton Beach, Christchurch—on floating timber (Suter 1913); Woodend Beach, Christchurch—off a buoy, M.C. Miller, December 1958; Heathcote Estuary—on Durvillaea sp., R.L.C. Pilgrim, 4 April 1962 (Pilgrim Colin. E8); Taylor's Mistake—on holdfasts of Durvillaea sp., R.L.C. Pilgrim, 25 November 1960 (Pilgrim Colin. TM 23-37); Menzies Bay, Banks Peninsula, R.L.C. Pilgrim, 21 May 1955 (Pilgrim Colin. 59-64). CHATHAM ISLANDS: Pigeon Bay, Professor Schauinsland (Bergh 1900). CAMPBELL ISLAND: Perserverence Harbour—under stones, at low water, T. Mortensen, 9-10 December 1914 (Odhner 1924, Powell 1955). (I am sceptical of the habitat cited by Odhner for Fiona pinnata at Campbell Island.)

WORLD LOCALITY RECORDS (excluding those from New Zealand)

GREAT BRITAIN: Alder and Hancock 1855, Pruvot-Fol 1954. 142 Fig 1 Photographs taken underwater of Fiona pinnata amongst Lepas testudinata on the holdfast of a drifting Durvillaea antarctica plant, off the Cavalli Islands, Northland, New Zealand, 31 December 1978. TANE 25, 1979 143 MEDITERRANEAN SEA — SPAIN AND CANARY ISLANDS: Ros 1976. FRANCE: Pruvot-Fol 1954; ITALY: Kropp 1931; ISRAEL: Barash and Danin 1971. WESTERN ATLANTIC: Bayer 1963; Marcus 1977. CALIFORNIA: Marcus 1961; Bennett 1966; MacFarland 1966; Sphon and Lance 1968; Holleman 1972. AUSTRALIA: Burn 1962, 1966, 1967; Ben• nett 1966. LORD HOWE ISLAND: Burn 1966. JAPAN: Bieri 1966. CHINA SEA: MacFarland 1966. INDIAN OCEAN: MacFarland 1966. In addition approximately 30 Fiona pinnata and eggs were found by the present author amongst living Lepas anatifera and L. testudinata attached to driftwood that was being washed ashore at the northern end of Cronulla Beach, near Sydney, Australia on 20 May 1979. Many Velella velella and Physalia physalis were also coming ashore, and a single Janthina janthina, still attached to its bubble raft, was found as well.

REMARKS

Alder and Hancock (1855) and MacFarland (1966) have given detailed accounts of the anatomy. Casteel (1904) described the early stages of development. More recently, Williams (1978) made an electron microscopical study of the oral and salivary glands. This has a low profile and because of the almost flat back, holds all of the cerata in the water immediately above. The cerata are very short for a longish aeolid (maximum size attained being 40mm). No other aeolid possesses membranous extensions to its cerata, possibly these are related to the shortness of the cerata themselves. The anus is situated on the back — another unusual feature; the foot is very broad and mobile. All these features seem together to be, a large scale adaptation to sitting low down and living attached amongst the prey in the often-turbulent conditions at the sea surface. The short, stubby tentacles would appear to be part of this same modification. Another very special feature is the extremely long and thin (when protruded) penis which is equipped with a strong retractor muscle. It is remarkable that the penis form of this aeolid closely parallels that of the barnacles (M.C. Miller pers. comm. 1979). Fiona pinnata eats the Lepas species barnacles with which it lives. Most authors do not go beyond the category "lepadids" to specify exactly which species of Lepas they found Fiona associated with. The Cavalli Islands specimens were found amongst Lepas testudinata Aurivillius (see Foster 1978). MacGintie and MacGintie (1949) found Fiona with Lepas fascicularis Ellis and Solander. MacFarland (1966) reported it as occurring with Lepas hilli (Leach). Bieri (1966) found it with Lepas anserifera Linnaeus. Bennett (1966), Holleman (1972), Williams (1978), McDonald and Nybakken (1978) and B.A. Foster (pers. comm. 1979) all found it with Lepas anatifera Linnaeus. Therefore it appears that Fiona pinnata can sub• sist on at least five different species of Lepas. Holleman (1972) found other,

144 non-pelagic barnacles (Pollicipes polymerus (Sowerby) and Balanus glandula (Darwin)) would be eaten only if they were damaged so as to provide entry — under normal circumstances Fiona was unable to attack either suc• cessfully. This habit of feeding on barnacles has been adopted independ• ently by another nudibranch, the dorid Onchidoris fusca (Miiller)(Potts 1970). Apparently Fiona pinnata has a diet that is not restricted to Lepas species alone; there are instances of it living on, and eating the chondrophorans Velella velella (Linnaeus) and Porpita porpita (Linnaeus) (Pruvot-Fol 1954; Bayer 1963; Burn 1966, 1967; MacFarland 1966) although it apparently refuses the siphonophore Physalia physalis (Linnaeus) (Bayer 1963). In addition, Bergh (1892) reported Fiona being found on the shells of Janthina spp., and also amongst floating clumps of Sargassum sp. There is the New Zealand record of it being found on the outside of a live Janthina globosa Swainson at Orua Bay, Manukau Harbour. McDonald and Nybakken (1978) summarized the food habits reported for Fiona pinnata from California. Not unexpectedly, F. pinnata has some ecological peculiarities associated with its pelagic existance. Bayer (1963) reported Fiona to grow from 8mm to maturity (approximately 20mm) in only four days. Holleman (1972) found a 900% increase in length over a 24-day period (i.e. an average 1.11mm increase in length per day amongst 12 specimens). This represents a much faster growth rate than any given for benthic nudibranchs (Thompson 1966; Potts 1970; Clark 1975; Harris 1975; Nybakken and Eastman 1978; Rivest 1978; Todd 1978), except possibly for Doridella obscura Verrill which can complete its life cycle in 26 days at 25 °C (Perron and Turner 1977). Free-swimming veliger larva of Fiona pinnata hatch after five days (Holleman 1972). Although it has not been reported yet, it is probable that veliger larvae are able to delay metamorphosis until they encounter a suitable drifting clump of lepadids or a chondrophore; an event that must occur very rarely in the open sea.

ACKNOWLEDGEMENTS

I am very grateful to Dr R.V. Grace for retrieving the Durvillaea clumps for my inspection, he suffered a boat-load of Planes cyaneus crabs in the process. I also acknowledge assistance given by Dr M.C. Miller, Dr B.A. Foster and Mr N. Douglas who permitted me to include their New Zealand records of Fiona pinnata.

REFERENCES

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