Xylophaga dorsalis (Turton, 1819)

Fig. 9 g–i

Teredo dorsalis Turton, 1819 (p. 185).

Xylophaga dorsalis — Turton 1822 (pp. 16, 253; pl. 2, figs. 4–5).

Xylophaga dorsalis Turton—Jeffreys 1882 [a] (p. 947); Hidalgo 1917 (p. 744); Tebble 1966 (p. 187, text-fig. 100c).

Xylophaga dorsalis dorsalis (Turton, 1819) — Nordsieck 1969 (p. 153, pl. 22, fig. 87.30).

Xylophaga dorsalis (Turton) — Di Geronimo & Panetta 1973 (p. 110).

Xylophaga dorsalis (Turton, 1819) — Cossignani et al. 1992 (figs. 397–397A); Poppe & Goto, 1993 (p. 132, pl. 25, fig. 7); Giribet & Peñas 1997 (fig. 108); Repetto et al. 2005 (p. 349, mid left fig.); Oliver et al., 2016 (online resource).

Diagnostic characters. Subrounded shell; segmented internal umbonal-ventral ridge ending in a rounded condyle; hook-like denticle on the ventral part of the umbonal reflection; median shallow radial depression bordered backward by a strong radial rib; finely granulose commarginal ribs on the anterior half, abruptly curved downward at the anterior one-fourth. Prodissoconch: shell type ST-2A; length about 270 µm; roundish outline; convex profile; P-1 not visible (but smaller than 100 µm); P-2 with regular low commarginal cordlets throughout and fine radials on the abapical stages; transition to the nepioconch rather well marked.

Occurrence. Box-corer samples BC66 (3 specimens), BC72 (10); cores BC05 (5), BC21 (1), BC51 (1), BC72 (3). Maximum length: about 5 mm.

Distribution and habitat. The species is reported to be widespread in the Atlantic (Lofoten to the Azores) and Mediterranean, being a wood-boring eurybathic element distributed from intertidal to bathyal depths (Nordsieck 1969; Di Geronimo & Panetta 1973; Di Geronimo et al. 2001; Oliver et al. 2016). It was regarded as accidental in VP (bathyal mud) biocoenosis (Pérès & Picard 1964).

Fossil record. Miocene to Recent of the Mediterranean (Di Geronimo & Bellagamba 1985; Monegatti & Raffi 2001).