Lucinoma persolida ( Sacco, 1901 )

Kiel, Steffen & Taviani, Marco, 2018, Chemosymbiotic bivalves from the late Pliocene Stirone River hydrocarbon seep complex in northern Italy, Acta Palaeontologica Polonica 63 (3), pp. 557-568 : 563-564

Lucinoma persolida ( Sacco, 1901)

Figs. 6 , 7 .

1901 Dentilucina persolida sp. nov.; Sacco 1901: 82–83, pl. 19: 1, 2. 2011 Lucinoma sp. ; Taviani 2011: fig. 3h.

Material. — Four specimens; the largest specimen ( MGGC. 22014) consists of two disarticulated valves, 50 mm long and 46 mm high; the others ( MGGC.22015, NRM Mo184004, NRM Mo184005) are articulated and single valves partly embedded in rock matrix; from the late Pliocene of Italy, Stirone seep complex .

Remarks.— Lucinoma persolida is distinct from the two extant Mediterranean Lucinoma species, L. kazani and L. borealis , by being less inflated and by having a more distinctive lunula. Among the two, L. borealis is more similar to Lucinoma persolida because of its similar outline and its straight anterior adductor muscle scar that stays close to the pallial line. The extant L. gagei Oliver and Holmes, 2006 from the Oman margin differs from L. persolida by its narrower anterior adductor muscle scar and its much more distinct posterodorsal groove.

Among fossil species, Lucinoma perusina ( Sacco, 1901) from the classical Miocene “Calcare a Lucina ” deposits throughout Italy (cf. Moroni 1966; Taviani 1994; Kiel and Taviani 2017) is more inflated, has less protruding umbones, and its posterodorsal area is more well-defined, by being broader and flatter, and more angular. Quite similar to L. persolida regarding shell outline is the early Miocene Japanese Lucinoma shinokii Hirayama, 1954 , but it is more strongly inflated than L. persolida and its internal features are unknown ( Hirayama 1954). Lucinoma acutilineata ( Conrad 1849) , the most common lucinid at Pliocene seep deposits in Japan ( Majima et al. 2005a) differs from L. persolida by its more angular outline of the whorl. Compared to the recently described Lucinoma saetheri from Miocene seep deposits in New Zealand ( Amano et al. 2018), L. persolida has sharper ribs and a lower shell with more prominent umbones.

Stratigraphic and geographic range. —Late Pliocene of northern Italy.

Figures

Fig. 6. The lucinid bivalve Lucinoma persolida (Sacco, 1901) from the late Pliocene of Italy, Stirone River seep deposit. MGGC.22014, left (A) and right B) valves; in dorsal views (A1, B1), views of the interior including hinge and muscle attachment scars (A2, B2), and views of exterior (A3, B3).

Fig. 7. The lucinid bivalve Lucinoma persolida (Sacco, 1901) from the late Pliocene of Italy, Stirone River seep deposit. A. MGGC.22015, small articulated specimen, view of right valve (A1), dorsal view (A2). B. NRM Mo184004, articulated specimen, view of left valve (B1), dorsal view (B2).