Asperarca nodulosa Muller 1776

Asperarca nodulosa (Müller, 1776)

Fig. 3 j–m

Arca nodulosa Müller, 1776 (p. 247, n. 2984).

Arca nodulosa Müller—Jeffreys 1879 (p. 570).

Acar nodulosa nodulosa (Müller, 1776) — Nordsieck 1969 (p. 21, pl. 3, fig. 10.30).

Acar nodulosa scabra (Poli, 1795) — Nordsieck 1969 (p. 21, pl. 3, fig. 10.31).

? Barbatia nodulosa (Mull.), 1776 — Sirna & Masullo 1978 (p. 104, pl. 1, fig. 4).

Acar nodulosa scabra (Poli) —Di Geronimo 1979[a] (p. 135, pl. 6, figs. 1–3).

Barbatia nodulosa (O.F. Müller, 1766) — Poppe & Goto 1993 (p. 43, pl., fig. 1).

? Barbatia scabra (Poli, 1795) — Salas 1996 (p. 46).

Asperarca nodulosa (Müller, 1776) — La Perna 1998 (p. 11, pl. 2, figs. 1–4; pl. 3, fig. 5); Mastrototaro et al. 2010 (fig. 5 f); Oliver et al. 2016 (online resource).

Asperarca nodulosa (O.F. Müller, 1776) — Giannuzzi-Savelli et al. 2001 (p. 70, figs. 82–86); De Frias Martins et al. 2009 (p. 67, fig. 300).

Asperarca nodulosa (Mueller O.F., 1776) — Repetto et al. 2005 (p. 286, mid left fig). Asperarca nodulosa (Müller O.F., 1776) — Beck et al. 2006 (p. 94, bottom fig). Asperarca nodulosa (Mueller) —Rosso et al. 2010 (figs. 5 A, 14 L).

Diagnostic characters. Brownish subrectangular shell; gentle but distinct ventral sinuation; obtuse angulation running from beaks to postero-ventral margin; uneven commarginal folds crossed by several radial riblets developing into short, fluted spines above the posterior angulation. Prodissoconch: shell type ST-2D; length about 190 µm; roundish D-shaped outline; convex profile; P-1 with a small dorsocentral bump; P-1 surface sculpture somewhat eroded, appearing weakly rough, with faint antimarginal striation; P-2 a very narrow rim, barely separated from P-1; transition to the nepioconch well marked, somewhat step-like.

Remarks. The recently described A. secreta (La Perna, 1998) appears to be the most closely related taxon, differing primarily in having much smaller dimensions (4 mm vs. 15 mm); see La Perna (1998) for a complete comparison.

Occurrence. Box-corer samples BC04 (4 specimens), BC05 (5), BC10 (1), BC11 (5), BC22 (28), BC41 (1), BC66 (46), BC67 (12), BC68 (1), BC70 (1), BC71 (54), BC72 (27); cores BC04 (2), BC05 (9), BC21 (6), BC51 (18), BC67 (17), BC72 (7). Maximum length: 12.5 mm.

Distribution and habitat. Asperarca nodulosa occurs from the subarctic (Norway) to West Africa and into the Mediterranean. It lives attached by byssus to deep water corals, stones and gravel, gradually moving from shelf to bathyal depths going southwards, thus showing both a cold-temperate and eurybathic adaptation (Poppe & Goto 1993; La Perna 1998; Oliver et al. 2016). It was regarded as a preferential or accompanying element of CB (deepsea white corals) biocoenosis (Pérès & Picard 1964; Di Geronimo 1979[a]; Di Geronimo & Bellagamba 1985). In the Santa Maria di Leuca CWC biotope, it was found on dead colonies of Madrepora oculata and hard substrates (Mastrototaro et al. 2010), being abundant in framework-building coral, and common in coral rubble and solitary coral thanatofacies, as well as on hardgrounds (Rosso et al. 2010).

Fossil record. Miocene to Recent (Monegatti & Raffi 2001); very common in bathyal Pleistocene of central and southern Italy, often referred to as Acar or Barbatia scabra (Monterosato 1872; Di Geronimo 1979[a]; Di Geronimo & Bellagamba 1985; Di Geronimo & La Perna 1997; La Perna 1998; Di Geronimo et al. 2005).