Kurtiella cf. tumidula ( Jeffreys, 1866 )

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 : 38

Kurtiella cf. tumidula ( Jeffreys, 1866)

Fig. 8 g–i

Montacuta tumidula Jeffreys, 1866 (p. 396).

Montacuta tumidula Jeffreys—Verrill & Bush 1898 (p. 781, pl. 93, fig. 6; pl. 94, figs. 1–2). Mysella tumidula (Jeffreys, 1865) — Nordsieck 1969 (p. 92, pl. 14, fig. 52.14).

Mysella tumidula ( Jeffreys, 1866) — Palazzi & Villari 2001 (p. 26, fig. 116); Repetto et al. 2005 (p. 317, mid left fig.). Kurtiella tumidula ( Jeffreys, 1866) — Gofas & Salas 2008 (p. 130, fig. 14); Oliver et al. 2016 (online resource).

Diagnostic characters. Ovate-triangular, inequilateral shell; longer and expanded anterior side; nearly pointed posterior side; 2 divergent cardinal teeth in the right valve; 2 corresponding dorsal margin projections in the left valve. Prodissoconch: shell type ST-2A; length about 260 µm (P-1 about 110 µm); ellipsoidal outline; low convex profile; P-1 surface densely pitted; P-1/P-2 boundary rather well defined, slightly elevated; P-2 with fine concentric growth welts; transition to the nepioconch well marked.

Remarks. The Leuca specimens do not fully conform with published K. tumidula in terms of larval shell characters. The prodissoconch of the specimens at hand is considerably (about 100 µm) smaller than that of specimens of K. tumidula as measured by some authors (e.g. Gofas & Salas 2008; Oliver et al. 2016). Otherwise, prodissoconch shape and P-1 dimensions are comparable. P-2 size difference could overstep mere species variability, so we prefer not to assign our specimens to K. tumidula .

Occurrence. Box-corer samples BC04 (1 specimen), BC11 (3), BC67 (2); cores BC04 (1), BC05 (5), BC21 (12), BC51 (8), BC67 (2), BC72 (21). Maximum length: 2.5 mm.

Distribution and habitat. Kurtiella tumidula was hitherto known to live from Norway to North America, the Azores, the Strait of Gibraltar and the Mediterranean entrance; past Mediterranean records referred only to worn empty shells of probable Pleistocene age ( Dautzenberg 1889; Verrill & Bush 1898; Gofas & Salas 2008). The present record (if confirmed) could therefore be the first Recent one for the species in the Mediterranean, even if no live specimens were recovered. Kurtiella tumidula is a commensal element (host unknown) dwelling on mud from the shelf edge to about 2000 m depth ( Jeffreys 1866; Nordsieck 1969; Gofas & Salas 2008; Oliver et al. 2016).

Fossil record. Pleistocene? of the Mediterranean ( Gofas & Salas 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).