Creseis virgula (Rang, 1828b) forma constricta Chen and Bé, 1964b

Overview

This is a shelled pelagic snail, up to 0.4 cm long, with a transparent, uncoiled shell. The cross-section is round. The surface is smooth. The shell is short and narrow, tube-shaped and slightly curved. The visceral mass is seen through the shell. It is a clumsy swimmer that feeds on phytoplankton and protozoa. It lives in the upper warm waters layers of the Atlantic Ocean (Creseis v. constricta).

Taxonomic Description

The shell is smooth except for some growth lines. The cross section of the shell is circular. It is conical and straight or slightly curved. A well defined constriction separates the protoconch from the adult portion of the shell; the protoconch has a distinct bulge. there is a gentle size increase towards the anterior part of the adult shell. The posterior end is round and brown.
The holotype is 3.5 mm long, 0.38 mm wide. The protoconch is 0.54 mm long and 0.12 mm wide.

Juveniles

The Creseis v. constricta protoconch is narrow but blunt at its tip. First it grows narrow then bulges outwards so that the anterior part of protoconch I is wide. Before the protoconch II and teleoconch are formed, a narrow constriction occurs.

Reproduction

This form is a protandric hermaphrodite.

Ecology

This form is phytophagous.

Distribution

This form is found in the N-Atlantic Ocean but probably has a wider distribution, see the Creseis v. constricta map.

Geological Record

This form is found in the Pleistocene of the Mediterranean.

Types

Creseis virgula conica Chen and Bé, 1964: 194, fig. 4d.
Types not officially indicated but probably present in Lamont Geological Observatory, USA.
Type locality: 44°00'N 41°00'W.

Kingdom Animalia
Phylum Mollusca
Class Gastropoda
Subclass Euthyneura
Order Thecosomata
Suborder Euthecosomata
Family Cavoliniidae
Subfamily Clioinae
Genus Creseis
Species Creseis virgula
Forma virgula

Status in World Register of Marine Species

Not included in WoRMS database

Scientific synonyms and common names

Creseis virgula (Rang, 1828b) forma constricta Chen and Bé, 1964b

Synonyms

Clio (Creseis) conica part Pelseneer, 1888a: 48
Creseis virgula var. constricta n. var. Chen and Bé, 1964b: 194
Creseis virgula forma virgula (part): Van der Spoel, 1967: 61

Bé, A. W. H. and Gilmer, A. W., 1977. A zoogeographic and taxonomic review of euthecosomatous Pteropoda. In: A. T. S., Ramsay (ed). Oceanic Micropalaeontology I. Acad. Press London: 733-808.

Chen, C. and Bé, A. W. H., 1964b. Seasonal distributions of euthecosomatous pteropods in the surface waters of five stations in the western North Atlantic. Bull. Mar. Sci. Gulf Caribb. 14 (2): 185-220.

Grazzini, V. C. and Rosenberg, H. Y., 1969. Étude paléoclimatique d'une carotte de Méditerranée orientale. Revue Geogr. phys. Géol. dynam. (2)11(3): 279-292, 3 figs, 1 pl.

Herman, Y., 1971b. Vertical and horizontal distribution of pteropods in quaternary sequences. In: B. M. Funnel and W. R. Riedel. The micropalaeontology of oceans: 468-486. Univ. Press, Cambridge.

Pelseneer, P., 1888a. Report on the Pteropoda collected by H. M. S. Challenger during the years 1873-1876, 2. The Thecosomata Reports on the scientific. Results of the voyage of H. M. S. Challenger during the years 1873-1876 (zool.) 23(1): 1-132, 2 figs, 2 pls.

Rampal, J., 1975. Les thécosomes (mollusques pélagiques). Systématique et évolution écologie et biogéographie méditerranéennes. Aix-Marseille (Thesis Univ. Provence CNRS AO 11932): 1-485, 15 tabs, 99 figs.

Solis, N. B. and Westernhagen, H. von , 1978. Vertical distribution of euthecosomatous pteropods in the upper 100 m. of the Hilutangan Channel Cebu, The Philippines. Mar. Biol. 48(1): 79-87.

Thiede, J., Pastouret, L. and Melguen, M., 1974. Sédimentation profonde au large du delta du Niger (Golfe de Guinée). C. R. Acad. Sci. Paris 278(D): 987-990, 2 pls.

Thiede, J., 1975b. Shell- and skeleton- producing plankton and nekton in the Eastern North Atlantic Ocean. 'Meteor' Forschungsergeb. (C)20: 33-79.

Spoel, S. van der, 1967. Euthecosomata, a group with remarkable developmental stages (Gastropoda, Pteropoda). J. Noorduyn and Zn, Gorinchem, 375 pp.

Summary (in Dutch also published separately)

Spoel, S. van der, 1976c. Pseudothecosomata, Gymnosomata and Heteropoda. Bohn, Scheltema & Holkema, Utrecht. 484 pp. 246 figs.

Wells, F. E., 1976d. Identification of juvenile stage of Cuvierina columnella (Rang, 1827). J. Conchol. Paris 113(3-4): 77-82.

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