Margarites imperialis Simone & Birman, 2006

Cavallari, Daniel C., Salvador, Rodrigo B., Dornellas, Ana P. S. & Simone, Luiz R. L., 2019, Calliostomatidae, Colloniidae, Margaritidae, and Solariellidae (Gastropoda: Trochoidea) collected by the Marion Dufresne (MD 55) expedition in southeastern Brazil, with description of a new species of Calliostoma, Zootaxa 4609 (3), pp. 401-428 : 416-418

Margarites imperialis Simone & Birman, 2006

( Fig. 7 A–F)

Margarites imperialis Simone & Birman, 2006: 14 , figs 6–10; Rios, 2009: 104, text fig. (in part); Dornellas & Simone, 2011: 19.

Type material. Holotype: MZSP 46025 . Paratypes: MZSP 46026 , 12 sh , ANSP 412951 , 1 sh , BMNH 20050261 , 1 sh, from type locality; Rio Grande do Sul, off Porto Alegre , 30º43’S 44º05’W , MZSP 40193 , ~ 90 m, 3 sh (Colella leg., 1978) .

Type locality. Brazil, Espírito Santo state, off Itapemirim , 21º37’S, 40º03’W, 900 m, IOUSP sta. E321 (09/ ii/1969) .

Previously known distribution. Off South-Southeastern Brazil, 21.62°S to 26.75°S, 46.91°W to 40.05°W, live specimens from 90– 900 m.

New occurrence. As far northeast as the Abrolhos Slope, 19°36’S– 18°58’S, 37°48’W– 38°53’W, down to 1200 m (shells only).

Material examined. Brazil: Espírito Santo: off São Mateus, Abrolhos Slope , 18°58’S, 37°48’W, MD55 sta. CB78 , 1200 m, MNHN, 2 sh (27/v/1987); 19°36’S, 38°53’W, MD55 sta. CB 93, 640 m, MNHN, 2 sh (30/v/1987). Rio de Janeiro: off Cabo Frio, 23°46’S, 42°10’W, MD55 sta. CB 105, 610 m, MNHN, 2 sh (06/v/1987). Additional non-MD55 material : Brazil: types .

Measurements. 5 whorls, H= 8.8 mm, D= 11.7 mm (largest specimen).

Remarks. The present material compares extremely well with the types, showing a shell sculptured by uniform cords that become more closely spaced at the base, three more widely spaced spiral cords from the periphery to the adjacent suture on each whorl ( Fig. 7 A, D ), a subsutural cord with round nodules ( Fig. 7 B ), and an umbilicus covered by a smooth callus ( Fig. 7 C ). A single exception is a poorly preserved specimen that exhibits both the subsutural spiral cord and the following cord ornamented by triangular spikes ( Fig. 7 E ). A considerable conchological variation in sculpture strength is known in many trochoid species (e.g., Quinn 1979; Marshall 1999). Thus, this case is here interpreted as intraspecific conchological variation. The present record extends the range of the species ca. 320 km northwest to the Abrolhos Slope and the maximum depth from 900 m to 1200 m.

Figures

FIGURE 7. Margaritidae and Solariellidae collected by the MD55 expedition. A–F. Margarites imperialis A–C. MNHN, sta. CB105, spm #1 (H=8.8 mm, D=11.7 mm). A. apertural view. B. apical view. C. umbilical view. D. MNHN, sta. CB105, spm #2 (H=8.6 mm, D=11.2 mm), apertural view. E. MNHN, sta. CB78, juvenile specimen (H=5.5 mm, D=6.6 mm), apertural view. F. MNHN, sta. CB93, juvenile specimen (H=4.3 mm, D=5.2 mm), apertural view. G–L. Bathymophila euspira. G–H. MNHN, sta. DC72 (H=4.0 mm, D=4.1 mm). G. apertural view. H. apical view. I. MNHN, sta. CB77 (D=3.2 mm), umbilical view. J–L. MNHN, sta. DC72 under SEM. J. apertural view. K. apical view. L. detail of apex.