Lucinoma zapotalensis ( Olsson, 1931 )

Kiel, Steffen, Hybertsen, Frida, Hyžný, Matúš & Klompmaker, Adiël A., 2020, Mollusks and a crustacean from early Oligocene methane-seep deposits in the Talara Basin, northern Peru, Acta Palaeontologica Polonica 65 (1), pp. 109-138 : 116

Lucinoma zapotalensis ( Olsson, 1931)

Fig. 5 .

1931 Phacoides (Lucinoma) zapotalensis sp. nov.; Olsson 1931: 49, pl. 5: 2, 5.

Material.— Three specimens ( NRM Mo187011–187013) and several unnumbered, mostly fragmentary specimens from Cerro La Salina blocks 1, 3, 6–9, upper Oligocene, Talara Basin, Peru .

Remarks.—This species was reported by Olsson (1931) only from the Mambri shales near Zapotal in southern Ecuador, but not from any of the seep deposits in the Heath shale in northern Peru. According to Olsson (1931), the Mambri shales are the equivalent of the Heath shale and also of late Oligocene age. Similar is the “middle” Oligocene Lucinoma playaensis ( Olsson, 1964) from the Playa Rica grits in northern Ecuador, though it differs from L. zapotalensis by having more numerous and more narrowly spaced ribs and a more rounded posterodorsal margin ( Olsson 1964: pl. 6: 7). Lucinoma acutilineatum ( Conrad, 1849) from the Miocene Astoria Formation in Oregon and Washington state, USA, is quite similar, but appears to differ from L. zapotalensis by being less inflated and having more widely spaced, and sharper, commarginal ribs; it also seems to have a more angular outline than L. zapotalensis ( Conrad 1849; Moore 1963).

Stratigraphic and geographic range.—Early Oligocene of the Talara Basin, northern Peru.

Figures

Fig. 5. The lucinid Lucinoma zapotalensis (Olsson, 1931) from early Oligocene seep deposit at Cerro La Salina (block 1, C; block 9, A) and Cerros El Pelado (block 2, B), Talara Basin, northern Peru. A. Internal mold of large left valve (NRM Mo187011), left valve showing anterior adductor muscle scar (arrow). B. NRM Mo187012, external sculpture on right valve. C. Articulated specimen (NRM Mo187013), showing external sculpture on left valve (C1) and lunule and ligament in dorsal view (C2).