Mulinia levicardo ( Smith, 1881 )

Signorelli, Javier H. & Pastorino, Guido, 2011, Revision of the Magellanic Mactridae Lamarck, 1809 (Bivalvia: Heterodonta), Zootaxa 2757, pp. 47-67 : 60-61

Mulinia levicardo ( Smith, 1881)

( Figure 13 )

Mactra (Mulinia) levicardo Smith, 1881: 39 , pl. 5 figs. 2–2b. Mactra levicardo Mabille & Rochebrune, 1889: 106 .

Mulinia laevicardo Carcelles, 1950: 80, 1951: 343 .

Diagnosis. Lunule and escutcheon not defined, small and weak ventrally projected chondrophore; pallial sinus short, horizontal.

Description. Shell oval to subcircular, subequilateral, inflated, with small umbos weakly inflated; external surface smooth with weak concentric ornamentation forming irregular growth lines more visible in the ventral area ( Fig. 13 A–B). Anterior and posterior ends rounded, without sharp angles, ventral margin curved; lunule and escutcheon poorly developed, not defined by lines. Internally white; right valve with two strong anterior and posterior lateral teeth with rounded cusps, ventral anterior and posterior more distal from cardinals. Cardinal teeth unfused, posterior one vertically oriented, anterior one oblique ( Fig. 13 G). Left valve with V-shaped cardinal tooth flanked on posterior side by an accessory lamella, lateral teeth elongated with rounded cusp ( Fig. 13 H); chondrophore small, ventrally poorly developed; pallial sinus short and U-shaped ( Fig. 13 C–F).

Type material. One complete syntype (NHM Reg. No.1879.10.15.67).

Type locality. Cockle Cove, in Magellanic Strait area, at 13 m depth.

Other material examined. Argentina. Patagonia (NHM 1829, 1 valve). Chile. Cockle Cove, Magellanic Strait (NHM 79.10.15.68, coll. by Coppinger, 2 valves).

Distribution. Magellanic Strait.

Remarks. The rareness of this species was revealed by the scarce specimens deposited in the malacological collections examined. In the original description, the author pointed out that only two specimens of this form were sampled during the trip of the H.M.S. “Alert”.

Figures

FIGURE 13. Mulinia levicardo, A – F: Syntype of M. levicardo (NHM Reg. No. 1879.10.15.67); G – H: hinge detailed according to the nomenclature developed by Bernard and Munier Chalmas, scale bar = 1 cm.