Argyrotheca cuneata (Risso, 1826)

Figures 40, 41

Terebratula cuneata Risso, 1826, p. 388, pl. 12, fig. 179.

Terebratula soldaniana Risso, 1826, p. 389, pl. 12, fig. 178.

Anomia pera Megerle von Mühlfeld, 1829, p. 205, pl. 1, fig. 1a–b.

Terebratula pera – Küster (1843), p. 30, pl. 2b, figs. 14–17.

Orthis pera – Philippi (1844), p. 69.

Argiope cuneata – Davidson (1852b), p. 373 Argiope (Cistella) cuneata – Gray (1853), p. 114.

.

Platidia anomioides (Scacchi & Philippi, in Philippi, 1844)

Terebratula (Argiope) cuneata – Lovell (1861), p. 185.

Argiope pera – Brusina (1866), p. 47.

Figures 42, 43

Megathyris (Cistella) cuneata – Dall (1870), p. 146.

Argiope barroisi Schulgin, 1885, p. 122, pl. 8, fig. 4.

Orthis anomioides Scacchi & Philippi in Philippi (1844), p. 69 –70, pl. 18, fig. 9.

Argyrotheca cuneata – Dall (1900), p. 44.

Description: Shell gently to moderately ventribiconvex. Outline transverse and semicircular with acuminate cardinal extremities to equidimensional subangular, occasionally with weakly indented front. Both dorsal and ventral valves with weak median furrow. Hinge line wide and straight. Ventral umbo typically high and straight. Anterior commissure rectimarginate to unisulcate. Ornament of approximately 8–16 coarse, radiating, broadly rounded ribs. Shell white, red or grey, and typically red between ribs. Large round to triangular pedicle opening extending into dorsal valve. Deltidial plates rudimentary. Shell matrix endopunctate. Brachial loop in dorsal valve long, simple, bilobed and anteriorly attached to median septum. Triangular dorsal median septum reaching 4/5 valve length with a peak at 2/3 valve length. Ventral valve with a distinct median ridge extending to 4/5 valve length. Maximum shell length 3 mm.

Depth range: 2–645 m depth (Logan 1979; Logan 2007). However, from the available data, it seems that this species is mostly found shallower than 60 m.

Temperature range: 12–20˚C (Brand et al. 2003).

Salinity range: 37–38 (Brand et al. 2003).

Geography: Southernmost Celtic Sea, the Mediterranean, Madeira, the Canary Islands and the Cape Verde Islands (Logan 1979; Brunton & Curry 1979; Simon & Willems 1999; Logan et al. 2007).

Superfamily Platidioidea Dall, 1870

Family PLATIDIIDAE Dall, 1870

Subfamily Platidiinae Dall, 1870

Genus Platidia Costa, 1852

Terebratula appressa Forbes, 1844, p. 193.

Platidia anomioides – Costa (1852), p. 48, pl. 3, figs. 4 and 6.

Morrisia anomioides – Davidson (1852c), p. 79 –80, pl. 14, fig. 29.

Morrisia davidsoni Deslongchamps, 1855, p. 443, pl. 10, figs. 20a–d.

Terebratula (Morrisia) anomioides – Lovell (1861), p. 184.

Terebratula (Morrisia) anomioides – Reeve (1861), pl. 10, fig. 40.

Terebratula (Morrisia) davidsoni – Reeve (1861), pl. 10, fig. 42.

Argiope (Zellania) davidsoni – Weinkauff (1867), p. 290.

Platidia davidsoni – Dall (1870), p. 143.

Platydia anomioïdes – Jeffreys (1878), p. 411.

Platydia davidsoni – Davidson (1880), p. 21.

Platidia seminula Philippi – Dall (1920) [partim], p. 332.

Description: Shell typically very uneven, concavoconvex to ventribiconvex, shaping itself after the substratum. Outline circular to transversely oval, but juveniles can be more egg-shaped. Hinge line straight and shorter than greatest shell width. Ornamentation of concentric growth lines, with randomly distributed pustules (tubercles) on ventral valve. Pustules missing on juvenile shells. Shell matrix endopunctate. Colour yellowish-brown or white. Pedicle foramen large and extending well into posterior part of dorsal valve. Deltidial plates narrow. Short brachidium (=lophophoral support) when fully developed, forming a brachial loop supported by short median septum. Median septum very high triangular and can reach slightly anterior of mid-valve length. Very short setae along valve margin. Maximum shell length 8 mm.

Depth range: 8–2190 m depth (Logan 2007).

Temperature range: -1.2–12.0˚C (Carpenter et al. 1869; this study).

Salinity range: 35.2–35.3 (Thomsen 2001).

Substrate: Attached to pebbles, shells and corals (Davidson 1887; Brunton & Curry 1979; Logan 1979; Thomsen 2001). Found on all from mud- to stone-dominated bottoms (Thomsen 2001).

Geography: SW of Faroe Islands, Florida, North of Shetland, the Hebrides, Western Approaches, Bay of Biscay, Portugal, Mediterranean, Azores, Morocco, Canary Islands, Cuba, the West Indies, Red Sea, Argentina, South Africa, southernmost S America, Prince Edward Islands, and Antarctica (Fischer & OEhlert 1891, 1892; Cooper 1973a; Brunton & Curry 1979; Thomsen 2001; Logan et al. 2007, 2008; Zezina 2008).