Limatula, S. V. Wood, 1839

Allen, J. A., 2010, The Recent species of the genera Limatula and Limea (Bivalvia, Limacea) present in the Atlantic, with particular reference to those in deep water, Journal of Natural History 38 (20), pp. 2591-2653 : 2592-2593

Subgenus Limatula s. s.

Description. Shell elongate, oval, usually subequilateral, occasionally equilateral, inflated, orthocline or opisthocline, usually small auricles present, with or without auricular sinuses, sculpture of fine ribs, as size increases more riblets may be interpolated, enlarged median ribs may or may not be present; hinge plate margin straight, or slightly angled, without teeth and usually narrow; resilifer relatively elongate lozenge-shape.

Subgenus Stabilima Iredale, 1939

Type species: Stabilima tadena Iredale, 1939 (original designation: Recent).

Description. Shell elongate, oval, equilateral, inflated, orthocline or slightly opisthocline, small auricles present with shallow auricular sinuses, sculpture relatively broad, radial, serrate, beaded or prickly ribs, central ribs usually larger, reticulate where crossed by incremental concentric ridges, median rib not dominant but weak median groove may be present internally; hinge plate margin angulate, resilifer relatively short and subcircular with an anterior and a posterior ridge extending to limit of auricles.

Subgenus Limatuletta Fleming, 1978

Type species: Limatula japonica Adams, 1864 (original designation: Recent).

Description. Shell moderately elongate, oval, moderately inflated, equilateral or slightly inequilateral, orthocline or slightly opisthocline, small auricles, auricular sinuses either absent or weak, sculpture modest number of strong radial ribs, triangular in cross-section, imbricated, or prickly where crossed by incremental

concentric ridges, extend over all the shell, juveniles with concentric lirae, median rib not particularly marked, but internally a well-defined square cut median sulcus; hinge plate margin straight or angulate, extremely narrow, resilifer extremely slender.

Subgenus Antarctolima Habe, 1977 (~ Squamilima Fleming, 1978)

Type species (of both): Lima (Limatula) hodgsoni Smith, 1907 (original designation: Recent).

Description. Shell somewhat elongate, broadly pyriform, moderately inflated, equilateral or slightly inequilateral, orthocline or slightly opisthocline, auricles small with small sinus, sculpture numerous ribs, decussate where crossed by incremental concentric ridges, may form prominent cusp-like scales on ribs, ribs extend over shell surface but less prominent laterally, median rib not marked,

but internally a square cut median sulcus; hinge plate margin straight or angular relatively narrow, resilifer slender and moderately elongate.

Subgenus Limea Bronn, 1831

Type species: Ostrea strigilata Brocchi, 1814 (original designation: Miocene).

Description. Shell small, ovate, equivalve, equilateral or almost so, moderately inflated, robust, small auricles, prominent radiating nodulose or scaly ribs, concentric striae or lamellae, margin crenate, umbo prominent; hinge plate crossed with series of teeth on either side of triangular resilifer.

Subgenera

Iredale (1924 and 1929) listed a number of new generic names for Australian Recent limeans with little or no definition. These include Gemellima, Isolimea , Escalima and Notolimea , the latter supplanting Limea Bronn in some accounts ( Barsotti, 1975; Lucas, 1980; Salas, 1994). At present there is little evidence that the Iredale names are of generic status. Stuardo (1968) in a highly significant and extensive thesis on the Limidae and Kilburn (1990) both took a more sympathetic view and for the most part recognized these subgenera and, like Fleming (1978) for Limatula , recognized various subgroups. Nevertheless, it is such a conservative group with such a continuum of form, which is emphasized further by the description of new species in this paper, that these subdivisions should be regarded

with great caution.