Radiolucina cancellaris (Philippi, 1846)

Garfinkle, Elizabeth A. R., 2012, A review of North American Recent Radiolucina (Bivalvia, Lucinidae) with the description of a new species, ZooKeys 205, pp. 19-31 : 21-22

Radiolucina cancellaris (Philippi, 1846) Figure 2, 5b

Lucina cancellaris Philippi, 1846: 21.

Radiolucina cancellaris - Olsson 1961: 547.

Radiolucina cancellaris - Keen 1971: 1064.

Radiolucina cancellaris neotype - Coan and Valentich-Scott 2012: 359.

Shell shape.

Subovate, inflated; maximum length: 7.2 mm, maximum height: 8.0 mm; beaks prosogyrate.

Sculpture and color.

Average 12 (10-15 n=76) non-bifurcating radial ribs, overlain by thin commarginal lamellae that continue through interspaces, producing a reticulate pattern; interspaces sunken, thin towards beak, progressively widening ventrally; anterior end smooth, with fine commarginal striae; posterior end with a series of average 13 (12-15 n=20) thick spines of varying heights protruding from shell; inner ventral margin crenulations thin, closely spaced; interior color white to cream, shiny.

Hinge.

Hinge plate thick, straight with slight curve; cardinal teeth small, right valve posterior thin, anterior thick, left valve middle tooth wide; lateral teeth large, posterior vertical, anterior horizontal;ligament sunken above the cardinal teeth.

Adductor scars and pallial line.

Pallial line discontinuous, broken into small and large segments, with one small circular indentation directed ventrally; anterior adductor scar large, narrow, diverging from pallial line for about a quarter of its length; posterior adductor scar small, wide, pallial line joins at most ventral point.

Type specimens and type locality.

Neotype, SBMNH 149738 ( Coan and Valentich-Scott 2012), length 6 mm, height 6 mm. Cabo Haro, Sonora, Mexico, 37-73 m.

Distribution.

Known from Isla Cedros, Pacific coast of Baja California (28.2°N) [Keen, 1971], into the Golfo de California as far north as near its head at Puerto Peñasco, Sonora (31.3°N) [LACM], México, to Isla San Lorenzo, Lima, Perú (12.1°S) [LACM]; intertidal zone to 212 m [LACM]. Also in the Pliocene of Ecuador and the Pleistocene of Baja California.

Literature.

Britton (1972), Coan and Valentich-Scott (2012), Dall (1901), Keen (1971), Olsson (1961).

Remarks.

Shell shape and ribs vary at different stages of growth. Due to this, it can be difficult to distinguish variants of Radiolucina cancellaris . The number of ribs is consistent during growth (average 12); however sometimes they were thinner or thicker, and inconsistently extended to the ventral margin. Bifurcation and/or intercalary ribs are sometimes present depending on the stage of growth.