Tonicella rubra (Linnaeus, 1767)

Avila, Sergio P. & Sigwart, Julia, 2013, New records for the shallow-water chiton fauna (Mollusca, Polyplacophora) of the Azores (NE Atlantic), ZooKeys 312, pp. 23-38 : 29

Tonicella rubra (Linnaeus, 1767) Fig. 8

Chiton laevis Pennant, 1777 =

Chiton minimus Spengler, 1797 =

Chiton incarnatus Reeve, 1848 =

Chiton latus Leach, 1852 =

Chiton ruber var. oblonga Jeffreys, 1865 =

Tonicella rubra var. index Balch, 1906 =

Tonicella beringensis Jakovleva, 1951 =

Tonicella granulata Jakovleva, 1952 =

Tonicella zotini Jakovleva, 1952 =

Tonicella beringensislucida Sirenko, 1974 =

Chiton cinereus Linnaeus, 1767 sensu Fabricius, 1780!

Records for the area.

This is the first record for the Azores.

Distribution and biotope.

This species has an Arctic-circumboreal distribution, including the Arctic Ocean (Barents Sea, White Sea, Spitzbergen), the North Pacific (northern Japan), the western North Atlantic as far south as New London (Connecticut) ( Kaas and van Belle 1985b) and the eastern Atlantic from Greenland and Scandinavia to Britain and Ireland ( Kaas and van Belle 1985b), and now the Azores.

Material examined.

Dom João de Castro seamount (20 m depth: DBUA 891, 1 spm).

Fossil record.

No fossil representatives are known from the Azores.

Description (abridged).

Up to 15 × 9 mm in the North Atlantic; dorsal elevation ratio = 0.29. Valves beaked, girdle narrow. Tegmentum appears smooth, with growth lines clearly visible under magnification. Colour orange to pinkish, generally with small reddish-brown blotches. Girdle relatively narrow and covered by small scales, appearing sandy to the naked eye, coloured like the tegmentum, but sometimes with white or cream markings particularly at the junctures between valves.

Remarks.

The Dom João de Castro Bank (Lat 38°13.3'N, Long 26°36.2'W) is a shallow seamount (minimum depth = 13 m) located between the islands of São Miguel and Terceira. The last eruption was in December 1720 when a small island (~1 km long and 150 m high) was formed ( Agostinho 1934). This island disappeared within a year and nowadays the seamount is capped by a submarine caldera (300 × 600 m) approx. 40 m deep, with strong hydrothermal activity in vents located at approx.20 m depth ( Ávila et al. 2004; Cardigos et al. 2005).