Microvoluta corona, Simone & Cunha, 2012

Simone, Luiz Ricardo L. & Cunha, Carlo M., 2012, Taxonomic study on the molluscs collected in Marion-Dufresne expedition (MD 55) to SE Brazil: Xenophoridae, Cypraeoidea, mitriforms and Terebridae (Caenogastropoda), Zoosystema 34 (4), pp. 745-781 : 768-770

publication ID

https://doi.org/ 10.5252/z2012n4a6

publication LSID

lsid:zoobank.org:pub:857CAD31-66E1-4CEE-AB4D-CCD64541D0EF

persistent identifier

https://treatment.plazi.org/id/03AA8317-C65F-0D4F-FCB1-99C8C88F0FE5

treatment provided by

Felipe

scientific name

Microvoluta corona
status

n. sp.

Microvoluta corona n. sp.

( Fig. 7 View FIG E-G)

TYPE MATERIAL. — Holotype: Brazil, Espírito Santo, off Itaúnas, continental slope of Abrolhos , 19°01’S, 37°47’W, 1500-1575 m depth, MNHN 25243 View Materials ( Fig. 7 View FIG E-G) ( MD55 , stn DC79 , Bouchet, Leal & Métivier coll., 28.V.1987). GoogleMaps

TYPE LOCALITY. — Brazil, Espírito Santo, off Itaúnas, continental slope of Abrolhos, 19°01’S, 37°47’W, 1500- 1575 m depth ( MD 55, stn DC 79).

DISTRIBUTION. — Known only from type locality.

ETYMOLOGY. — The specific epithet is derived from the Latin word “corona”, meaning crown, an allusion to the subsutural ornamentation of the shell.

DIAGNOSIS. — Shell up to 5.5 mm, elliptical (width c. 2 times length). Sculpture mainly axial, subsutural, uniform nodes, located on shoulder. Protoconch blunt, mammillary, with one whorl. Aperture wide, c. ½ shell length.

DESCRIPTION

Shell: size 5.5 mm, outline elliptical; width c. 54% of length. Colour pure white ( Fig. 7E, F View FIG ); surface smooth, glossy. Protoconch blunt, mammillate, comprising c. 6% of shell length and c. 20% of shell width; about two rounded, smooth, glossy whorls; suture unclear ( Fig.7E, F View FIG ); transition with teleoconch indistinct. Spire c. 44% of shell length; spire angle c. 55°. Teleoconch up to four whorls; each whorl strongly shouldered; area between shoulder and upper suture horizontal, comprising c. ¼ of whorl length; remaining area weakly concave, with almost straight and vertical profile.Sculpture uniform, large nodes on shoulder, producing weak axial threads, below nodes, gradually disappearing before inferior suture; c. 10 in penultimate whorl; interspaces of axial threads roundly concave, as wide as threads. Ventral region of body-whorl with anterior ⅔ smooth. Aperture elliptic, oblique c. 30° in relation to shell longitudinal axis; comprising c. 53% of shell length and c. 40% of shell width. Outer lip simple, rounded, thick; with small upper notch corresponding to shoulder ( Fig. 7E, G View FIG ). Inner lip weakly concave, callus inconspicuous; four oblique folds uniformly distributed and similar-sized in middle and inferior thirds, comprising c. 80% of inner lip area; upper folds more horizontal, becoming oblique towards canal ( Fig. 7G View FIG ). Canal wide and short; almost as wide as aperture width. No umbilicus.

MEASUREMENTS (in mm). — Holotype: 5.5 × 3.0.

HABITAT. — Sandy bottoms, 1500-1575 m depth.

REMARKS

Microvoluta corona n. sp. is somewhat similar to M. blakeana (Dall, 1889) from the Gulf of Mexico (146-1170 m depth), differing in having strong subsutural nodes, taller spire and wider aperture. Differs from M. intermedia Dall, 1890 , from the Caribbean, in being shorter, fewer whorls, by subsutural nodes proportionally larger and fewer, lacking subsutural spiral thread. Microvoluta corona n. sp. still differs from Peculator verconis Iredale, 1924 by its subsutural nodes, and by whorls forming shoulder.

The generic attribution is not absolutely secure, because only the type species of Microvoluta , M. australis Angas, 1877 , lacks subsutural nodes ( Pechar et al. 1980). However, most of the species attributed to this genus have subsutural nodes ( Bouchet & Kantor 2003). Microvoluta corona n. sp. has some similarities with above mentioned species, allowing the generic attribution, rather than other volutomitrid and even marginellid genera, such as protoconch mammillate of two whorls, and inner lip smooth inside.

DISCUSSION ON MITRIFORMS

The mitriform gastropods are not the most diverse group amongst the MD55 collected samples, and each species is represented by few and sometimes incomplete specimens.This is indicative that possibly they can be transported from shallower levels. The single exception is Nodicostellaria crassa , which was collected abundantly and alive. This species appears to be the dominant mitriform species in continental slope along the entire southeastern Brazilian coast, and one of the main gastropod predators.

As the above descriptions and taxonomic discussions demonstrate, the closest relatives to most species occur in northern Atlantic, mainly in Caribbean Sea. Despite the similarities, most species demonstrate to be different, which can indicate a relationship, but under different conditions in the western Atlantic deep-water environment, possibly because of the influence of large rivers like the Amazon River, oceanic currents, or some other environmental factor of isolation.

Superfamily CONOIDEA Fleming, 1822

Family MITROMORPHIDAE Casey, 1904

MD

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