Tugonia (Distugonia) decurtata (A. Adams, 1851)

Figure 6 L

Sphenia decurtata A. Adams, 1851: 88 –89.

Cryptomy decurtata (A. Adams, 1851) — A. Adams, 1868: 366; Beets, 1949: 273, 277; Beets, 1950: 17.

Mya decurtata (A. Adams, 1851) — Sowerby, 1875: sp. 11, pl. III, fig. 11.

Distugonia decurvata (A. Adams, 1851) — Habe, 1951: 75, pl. 12, figs. 15 & 16; Habe, 1961: 140, pl. 63, fig. 11; Habe, 1968: 205, pl. 63, fig. 11; Habe, 1977: 279, pl. 58, figs. 7 & 8; Wu, 1980: 189; Xu, 1997: 230; Xu, 2008: 590; Okutani, 2000: 1021, pl. 508, fig. 4 [spelling error].

Distugonia decurtata (A. Adams, 1851) — Bernard et al. 1993: 107.

Tugonella decurtata (A. Adams, 1851) — Huber, 2010: 461 (text-fig.).

Distribution and habitat. Miocene to Recent. Taiwan, China; Japan; Philippines. Intertidal mud bottom to 50 m.

Type locality. Catanuan, Province of Tayabas, Island of Luzon, in sand at low water depths.

Diagnosis. Length to 30 mm; shell slightly inflated, elongate-oval; umbo prominent, situated subcentral; posterior area demarcated by ridge; chondrophore projecting in the left valve, right valve resilifer compressed; pallial sinus shallow, not reaching further anterior than posterior adductor scar; pallial line thin.

Remarks. This species had been incorrectly spelled as decurvata by some Japanese and Chinese authors.