Abra longicallus ( Scacchi, 1835 )

Negri, Mauro Pietro & Corselli, Cesare, 2016, Bathyal Mollusca from the cold-water coral biotope of Santa Maria di Leuca (Apulian margin, southern Italy), Zootaxa 4186 (1), pp. 1-97 : 39-41

Abra longicallus ( Scacchi, 1835)

Fig. 8 n–p

Tellina longicallus Scacchi, 1835 (p. 79, pl., fig. 6).

Scrobicularia longicallus Scacchi—Jeffreys 1882 [a] (p. 926).

Abra longicallis [sic] Scacchi, variety americana Verrill & Bush 1898 (p. 778, pl. 83, figs. 6–7).

Abra longicallis [sic] (Scacchi, 1836)— Nordsieck 1969 (p. 137, pl. 19, fig. 73.06).

Abra longicallus (Scacchi) — Di Geronimo & Panetta 1973 (p. 106); Tebble 1966 (p. 153, text-figs. 79a–b); Rosso et al. 2010 (fig. 11 B).

Abra (Syndosmya) longicallus (Scacchi) — Di Geronimo 1974 (p. 156, pl. 5, fig. 3).

Abra (Syndosmya) longicallus (Scacchi, 1834) — Cossignani et al. 1992 (fig. 359).

Abra longicallus (Scacchi, 1834) — Poppe & Goto 1993 (p. 116, pl. 20, fig. 9); Repetto et al. 2005 (p. 336, top right fig.); Mastrototaro et al., 2010 (fig. 5 j).

Abra longicallus ( Scacchi, 1835) — Oliver et al. 2016 (online resource).

Diagnostic characters. Slightly inequilateral, elliptical shell; shorter and narrower subtruncate posterior side; rounded anterior side; blunt postero-dorsal ridge; internal part of the ligament on a moderately long and narrow resilifer; outer surface bearing growth lines only. Prodissoconch: shell type ST-2A; length about 210 µm (P-1 about 80 µm); inequilateral (longer anteriorly), slightly ellipsoidal outline; somewhat pointed posteroventral margin; convex profile; P-1 surface weakly rough; P-1/P-2 boundary weak; P-2 with dense concentric lines; transition to the nepioconch well marked.

Occurrence. Box-corer samples BC04 (26 specimens), BC05 (54), BC06 (2), BC11 (4), BC41 (1), BC66 (45), BC67 (48), BC68 (1), BC70 (12), BC71 (225), BC72 (673); cores BC04 (16), BC05 (78), BC21 (49), BC51 (31), BC52 (7), BC67 (9), BC72 (81). Maximum length: 19 mm.

Distribution and habitat. The species occurs throughout the northern Atlantic and in the Mediterranean; it is a common circalittoral and bathyal element dwelling on muddy sand with low amounts of organic carbon (Buhl- Mortensen & Høisaeter 1993; Poppe & Goto 1993; Pons-Moyà & Pons 1999; Ceregato et al. 2007; Oliver et al. 2016). It was regarded as an exclusive characteristic element of VP (bathyal mud) biocoenosis ( Pérès & Picard 1964; Di Geronimo 1979[a]; Di Geronimo et al. 1982). The species was found alive in the bathyal of Taranto, among the Abra-Nucula biocoenosis ( Di Geronimo & Panetta 1973). In the Santa Maria di Leuca CWC biotope, it was found on muddy bottoms around coral colonies (Mastrototaro et al. 2010), being common in solitary coral, and very abundant in Gryphus-Isidella and mollusk mud thanatofacies (Rosso et al. 2010).

Fossil record. Miocene of central Italy; Pliocene of Italy; Pleistocene of Norway, central and southern Italy ( Monterosato 1872; Di Geronimo & Bellagamba 1985; Di Geronimo & La Perna 1997; Di Geronimo et al. 2005; Tabanelli 2008).

Figures

FIGURE 8. a – c: Montacuta substriata (Montagu, 1808); RV, sample BC 72, scale bars: 1 mm (a – b), 0.1 mm (c, prodissoconch); d – f: Tellimya tenella (Lovén, 1846); RV, sample BC 72, scale bars: 1 mm (d – e), 0.1 mm (f, prodissoconch); g – i: Kurtiella cf. tumidula (Jeffreys, 1866); RV, sample BC 67, scale bars: 0.5 mm (g – h), 0.1 mm (i, prodissoconch); j – m: Parvicardium minimum (Philippi, 1836); RV (j, m) and LV (k), sample BC 71, scale bars: 1 mm (j – k), 0.1 mm (l, prodissoconch), 0.02 mm (m, P – 1 detail); n – p: Abra longicallus (Scacchi, 1835); LV, sample BC 70, scale bars: 5 mm (n – o), 0.1 mm (p, prodissoconch).