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Taxon profile

species

Macromphalina alfredensis (Bartsch, 1915)

kingdom Animalia - animals »  phylum Mollusca - mollusks »  class Gastropoda - gastropods »  order Littorinimorpha »  family Vanikoridae »  genus Macromphalina

Scientific synonyms

Discopsis alfredensis Bartsch, 1915

Images

Macromphalina alfredensis

Author: Bartsch, P.

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Description

As Discopsis alfredensis Bartsch:
Shell small, sublenticular, white, excepting the nuclear whorls, which are pale chestnut brown. Nuclear whorls two, small, well-rounded, forming an elevated helicoid spire with strongly impressed suture. Postnuclear whorls very wide, moderately rounded, marked by decidedly retractive, wavy riblets, which, on the last half of the last volution, become irregular and strongly wavy. These riblets arc about one-fourth as wide as the shallow concave spaces that separate them. The latter are crossed by spiral threads which are almost equal to the axial riblets in strength. There are about 20 of these between the summit and the periphery on the last turn. On the last half of the last turn these also become decidedly irregular and wavy, and the entire Sculpture of this portion of the shell assumes a crinkly appearance. Periphery strongly angulated. Base with a very broad funnel-shaped umbilicus, which occupies fully half the space, and which is bordered by a tumid area at its exterior limit; the space between this tumid area and the peripheral angle is slightly concave. The entire surface of the base is marked by the continuation of the axial riblets, which are somewhat sinuous and become closer approximated hero than on the spire. These riblets extend strongly into the umbilicus. The spaces between the riblets are marked by fine spiral striations. Aperture very large, very oblique, the basal and outer lip forming a decided angle at the periphery; posterior angle obtuse; outer lip decidedly patulous, thin, showing the external sculpture within; inner lip curved, thin, slightly reflected, the outer and the inner lip almost approaching each other on the parietal wall.
The type and another specimen of this species, Cat. No. 250533, U.S.N.M., come from Port Alfred (Coll. No. 1406). The type has 1.1 postnuclear whorls, and measures: Greater diameter, 1.8 mm.
Bartsch, P., 1915. Report on the Turton Collection of South African marine mollusks, with additional notes on other South African shells contained in the United States National Museum.
Author: Jan Delsing

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