Botula Mörch, 1853

(Fig. 1)

Type species. Modiola cinnamomea Lamarck, 1819, subsequent designation by Dall (1898: 792). Wilson & Tait (1984: 113), although referring to Dall (1898), incorrectly noted Mytilus fuscus Gmelin, 1791 as type species (see Discussion).

Diagnosis. Shell somewhat ovate to kidney-shaped, smooth; umbones terminal, prominent, somewhat coiled; siphons separate. The anterior retractor is fastened on the anterior thickened margin of the shell just below the umbones. The posterior adductor is small and the posterior retractor leaves a small scar above the adductor (Soot-Ryen 1955: text-fig. 70).

Remarks. Mörch (1853: 55) assigned to Lithophaga (Botula) three species: (1) Tamarindiformes arenaria Meuschen, 1787, with Modiola vagina Lamarck, 1819 and M. castaneus Gray (Rumphius 1705: pl. 46 fig. E) listed as synonyms, locality India Orientalis; (2) indet sp., no locality, and (3) L. (B.) fusca (Gmelin, 1791) referring to Lister’s pl. 359 fig. 197, with Mytilus brunneus Solander, 1786 and Modiola cinnamomea var. Lamarck, 1819 and M. favannii Potiez & Michaud, 1844 listed as synonyms, locality Insulae Antillarum. Based on the subsequent type species designation (Dall 1898: 792), only cinnamomea and fusca are members of Botula . The question remains, whether they are separate species or conspecific (see species problem).

Soot-Ryen (1969) considered Botula to belong to Modiolinae, although the genus does not fit to the general characters he lists for the subfamily: modioliform, beaks slightly behind anterior end, hinge margin smooth or finely striated vertically, shell surface usually lacking radial sculpture, periostracum commonly hairy, free-living, often nestling. Compared with Adula and Lithophaga, the proportions of the valves are relatively shorter and higher, the umbones inflated, the convex anterior and posterior dorsal margins thickened and crenulate in Botula (Turner & Boss 1962), but there are definitely no crenulations in Botula . The only ornament of the shells, if present, results from growth lines or steps (Fig. 1).