Delectopecten vitreus Gmelin 1791

Delectopecten vitreus (Gmelin, 1791)

Fig. 5 a–d

Ostrea vitrea Gmelin, 1791 (p. 3328).

Pecten vitreus Chemnitz—Jeffreys 1879 (p. 561).

Chlamys vitrea Chemnitz—Hidalgo 1917 (p. 240).

Chlamys (Delectopecten) vitrea (Gmelin) — Tebble 1966 (p. 64, text-figs. 27a–b).

Delectopecten vitreus vitreus (Gmelin, 1789) — Nordsieck 1969 (p. 47, pl. 7, fig. 31.10).

Delectopecten vitreus (Gmelin) — Di Geronimo & Li Gioi 1980 (pl. 4, figs. 1–2); Di Geronimo & Bellagamba 1985 (pl. 3, fig. 3); Rosso et al. 2010 (fig. 5 C).

Delectopecten vitreus (Gmelin, 1791) — Thomsen & Vorren 1986 (pl. 5, fig. C); Barash & Danin 1992 (p. 254, fig. 272); Poppe & Goto 1993 (p. 65, pl. 9, fig. 7); Giannuzzi-Savelli et al. 2001 (p. 172, fig. 326); Petersen 2004 (p. 70, fig. 59); Repetto et al. 2005 (p. 297, top right fig); Mastrototaro et al. 2010 (fig. 5 h); Oliver et al. 2016 (online resource).

Delectopecten vitreus — Ceregato et al. 2007 (fig. 3.8).

Diagnostic characters. Subrounded, thin shell; moderately long anterior right auricle with 5/6 densely rugose radial riblets; deep byssal notch; left valve with subequal auricles; thin and slightly wavy commarginal lamellae; few radial rows of small nodes on the very anterior part of the shell and on the posterior auricles. Prodissoconch: shell type ST-2A; length about 220 µm (P-1 about 70 µm); P-2 roundish, weakly inequilateral (anterior side shorter); convex profile; P-1 surface rough; P-1/P-2 boundary ill-defined; P-2 with commarginal lines; transition to the nepioconch well marked.

Occurrence. Box-corer samples BC04 (5 specimens), BC05 (6), BC10 (1), BC11 (11), BC22 (3), BC41 (4), BC66 (38), BC67 (18), BC70 (3), BC71 (243), BC72 (165); cores BC04 (2), BC05 (25), BC21 (13), BC51 (7), BC67 (5), BC72 (42). Maximum height: 12 mm.

Distribution and habitat. Delectopecten vitreus is regarded as a cosmopolitan species, usually ranging from about 30 to 600 m but occasionally down to 3000 m water depth; it is more common in cold-water coral biotopes, where it lives attached by byssus to coral branches and hardgrounds (eventually on mud), becoming dominant in hypoxic conditions (Buhl-Mortensen & Høisaeter 1993; Poppe & Goto 1993; Ceregato et al. 2007; Oliver et al. 2016). The species was previously regarded as an exclusive characteristic element of the VP (bathyal mud) biocoenosis (Pérès & Picard 1964; Di Geronimo 1979[a]; Di Geronimo & Bellagamba 1985). In the Santa Maria di Leuca CWC biotope, it was found on living and dead colonies of Madrepora oculata (Mastrototaro et al. 2010), being common of framework-building coral, mollusk mud and foraminifer mud thanatofacies (Rosso et al. 2010).

Fossil record. D. vitreus is a common taxon in Pliocene and Pleistocene associations, often characterizing local paleocommunities along with other bathyal species, e.g. Kelliella miliaris (Ceregato et al. 2007); it is frequently recovered from Pleistocene bathyal deposits of central and southern Italy (Di Geronimo & Li Gioi 1980; Di Geronimo & Bellagamba 1985; Di Geronimo & La Perna 1997; Di Geronimo et al. 2005).