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Discussion

Anthosoma crassum has been recorded from many parts of the world and on a number of host species, the most frequent being members of the family Lamnidae.

Previous records include:

North-East Atlantic: on Lamna nasus—Aberdeen (Scott and Scott. 1913, p.109): Exmouth, Dartshire (Baird, 1850, p.299 and Leach, 1816, p.406 refer to same specimens); Devonshire (Leach, 1819, p.533); Φresund (Steenstrup and Lütken, 1861, p.397; Olssen, 1868, p.23); Hornbaek, Kattegat (Krøyer, 1838, p.295); Belgium (van Beneden, 1870, p.8).

• on Cetorhinus maximus—Newlyn, England (Birkett and Burd, 1952, p.392).
• on a shark, in the collection of the British Museum (Milne Edwards, 1840, p.483; Bassett Smith, 1899, p.468).
• on Mustelus mustelus—Belgium (van Beneden, 1870, p.5).

Mediterranean: on Isurus oxyrinchus—Palavas, France (Delamare Deboutville and Nunes-Ruivo, 1953, p.205); Genoa (Brian, 1902, p.7); Portoferraio (Brian, 1902, p.7); Adriatic (Valle, 1880, p.62).

North-West Atlantic: on I. oxyrinchus^*, L. nasus, Carcharinus obscurus, and Odontaspis taurus—Martha's Vineyard and Woods Hole, Mass. (Wilson, 1922, p.23, 1932, p.446).

• on Carcharodon carcharias—Woods Hole, Mass. (Wilson, 1924, p.12); Padre Is., Texas (Pearse, 1952, p.28).

South-East Atlantic: on I. oxyrinchus—Angola (Nunes-Ruivo, 1956 ^**); South Africa (Hee gaard, 1962, p.181).

• on Carcharias sp. and L. nasus—Table Bay and False Bay, South Africa (Barnard, 1955, p.272).

Indian Ocean: on Carcharias sp. and L. nasus—Durban (Barnard, 1955, p.272).

• on unnamed host—Port Natal, Durban (Wilson, 1923, p.13).

South-West Atlantic: on L. nasus—Mar del Plata (Brian, 1944, p.208).

• on Cetorhinus maximus—Mar del Plata (Fontes, 1949, p. 185).

North-East Pacific: on an unnamed host—Vancouver Is., and Californian Coast (Wilson, 1932, p.446).

• probably on I. oxyrinchus—45°11′ N, 174°54′ W (Lewis, 1966, p.67).
• on Carcharodon carcharias—Pokai Bay, Hawaii (Lewis, 1966, p.67).

North-West Pacific: on L. nasus—Toyama Bay, Japan (Yamaguti, 1936, p.12); Kesennuma, Japan (Shiino, 1955, p.50).

• on L. ditropis—Kesennuma, Japan (Shiino, 1957, p.370).
• on Prionace glauca—Tyôsi, Japan,
• on I. oxyrinchus—Owase, Japan.
• on Heptranchias perla—Kannoura, Japan (Shiino, 1955, p.50).
• on an unnamed host—Japan (Wilson, 1932, p.446).

South-East Pacific: on an unnamed host—Concepcion, Chile (Brian, 1944, p.208).

South-West Pacific: on Isurus oxyrinchus—Long Reef, nr. Port Jackson, New South Wales and French Pass, Cook Strait, New Zealand (Heegaard, 1962. p. 181).

• on L. nasus—Napier, New Zealand (Thomson, 1889. p.366); Otago, New Zealand (Kirk, 1888, p.31).
• on Cardiarias sp.—probably New South Wales and on an unnamed host—Port Jackson, New South Wales (Heegaard, 1962, p. 181).

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As well as its almost complete latitudinal distribution, Anthosoma crassum has been taken from Aberdeen, Scotland (59°9′ N) to Otago, New Zealand (45°45′ S).

Despite the numerous records of this species there have been few detailed descriptions or figures given. Those available (the fullest being those by Wilson 1922, p.23, pl. 1, figs. 1-9, Shiino, 1955, p.50, figs. 1-2, and Lewis 1966, p.67, figs. 4-6) suggest there is little variation except in size. Minor morphological variations shown or described could well be due to variations in optical equipment available to the various authors, with the possible exception of the female specimen figured by Brian (1944, fig. 44), which appears to have notches in the third pereiopod and plate of the second thoracic segment, as well as in the first and second pereiopods.

Size as measured by total length varies considerably, e.g. Yamaguti (1936) gives 8.8 mm - 11.0 mm for the female compared with Brian (1944) who gives 15.3 mm - 18.0 mm for this measurement, while Wilson (1922) gives the male as 8 mm - 10 mm compared with Brian (1944) who gives 12 mm - 13 mm. However when the range in the specimens available to me is considered (9.9 mm - 18.0 mm for the female, 9.0 mm - 16.7 mm for the male) the above apparent differences can be understood as individual variation. There is some suggestion of a host specific influence on size in my material but the numbers are not sufficient for statistical analysis and it would not be surprising if geographical factors, the site of attachment and the intensity of infection were also involved.

There appears to be considerable variation in the intensity of infection. Wilson (1922, p.25) states that this species "never occurs in any number on a host, but is more often solitary, although occasionally the two sexes are associated upon the same fish". Birkett and Bund (1952, p.392) on the other hand state that their specimens were numerous and did considerable damage to the host. In the present collection the author obtained one lot of 31 specimens from a single host which had been severely damaged, particularly on the dorsal surface of the tongue, which appeared to be partly hollowed out, while other collectors reported both single and multiple infections (see Material above).