TANAINAE Dana, 1852

Bamber, Roger N., 2011, The marine fauna and flora of the Isles of Scilly. Tanaidacea (Crustacea: Peracarida), Journal of Natural History 45 (29 - 30), pp. 1801-1815 : 1806-1807

Subfamily TANAINAE Dana, 1852

Genus Tanais Latreille, 1831 Tanais dulongii (Audouin, 1826)

Tanais dulongii Holdich and Jones, 1983 , 39–41; fig. 11.

Material

Nine specimens, low-littoral Audouinella -bedded sand, St Martin’s Head, northwest St Martin’s, 49 ◦ 58.51 ′ N, 06 ◦ 17.70 ′ W, 5 April 2001 ; 1 brooding ♀, 2 mancae ( BMNH 2009.289 – 291 ), low-littoral Audouinella -bedded sand on bedrock, Thomas Porth , St Mary’s, 49 ◦ 55.18 ′ N, 06 ◦ 18.56 ′ W, 27 June 2009 ; all coll. RNB. 6♀♀ (4 brooding), 2♂♂, 6 neuters, low-littoral algal turf, Appletree Bay , Tresco, 49 ◦ 56.48 ′ N, 06 ◦ 20.09 ′ W, 8 September 2010, coll. A.S.Y. Mackie. 9♀♀ (2 with oostegites, 1 brooding), 3♂♂, 11 neuters, 9 mancae, mid-littoral Audouinella -bedded sand, North Periglis , St Agnes, 49 ◦ 53.78 ′ N, 06 ◦ 21.03 ′ W, 9 September 2010 ; coll. RNB. 12♀♀ (2 with oostegites, 4 brooding), 3♂♂, 1 neuter, 4 mancae, mid-littoral algal turf in rock pool, Burnt island , Periglis Cove, St Agnes, 49 ◦ 53.74 ′ N, 06 ◦ 21.10 ′ W, 9 September 2010, coll. A.S.Y. Mackie. 2♀♀ (1 brooding), 2 neuters, low-littoral Audouinella - bedded sand, Pelistry Bay , St Mary’s, 49 ◦ 55.68 ′ N, 06 ◦ 16.82 ′ W, 12 September 2010 ; coll. RNB.

Other records

Near Green Island , Samson , 49 ◦ 55.87 ′ N, 06 ◦ 20.70 ′ W, littoral, 01 April 1983, coll. F. Gault ( NBN Gateway record). Porth Hellick, St Mary’s, 49 ◦ 54.93 ′ N, 06 ◦ 17.02 ′ W, mid- to low-water sand with red-algal turf, “2 to 3 per scrape”: 20 October 1998, coll. G.J. Bird ( CBRU Record No. P54093); Gugh Tombolo, St Agnes, 49 ◦ 53.62 ′ N, 06 ◦ 20.25 ′ W, mid- to low-water sand with red-algal turf, “2 to 3 per scrape”: 23 October 1998, coll. G.J. Bird ( CBRU Record No. W77015) .

Records of “ Tanais ”

“Present”, St Agnes, 49 ◦ 53.59 ′ N, 06 ◦ 21.16 ′ W; “present”, St Mary’s, 49 ◦ 54.82 ′ N, 06 ◦ 17.01 ′ W; “present”, Samson, 49 ◦ 55.87 ′ N, 06 ◦ 20.70 ′ W; all March 1983 ( Smith and Gault 1983).

Remarks

The accumulated sediments occurring among tight red-algal turf, such as that among Audouinella purpurea , is a preferred habitat for this littoral species around the British Isles, where a somewhat finer and more organic sediment is present than in adjacent beaches, and hence in which Tanais dulongii can build its burrows and feed. It was only found in this habitat in the Isles of Scilly. It can also occur in kelp holdfasts, and in rock crevices, where, in the southwest of England, the confamilial Parasinelobus chevreuxi (Dollfus 1898) has also been recorded. No tanaidaceans were found in algal holdfasts examined in 2009 and 2010 and no crevicial habitats were present owing to the geology of the islands (as discussed above).

The above records are from St Martin’s, St Mary’s, St Agnes, Tresco and Samson (assuming the records of Smith and Gault 1983, are of this species): Tanais dulongii is clearly present throughout the archipelago.