Gibberula

Gibberula
Scientific classification
Kingdom: Animalia
Subkingdom: Eumetazoa
Superphylum: Protostomia
Phylum: Mollusca
Class: Gastropoda
(unranked): clade Caenogastropoda
clade Hypsogastropoda
clade Neogastropoda
Superfamily: Muricoidea
Family: Cystiscidae
Subfamily: Persiculinae
Genus: Gibberula
Swainson, 1840
Type species
Marginella zonata Swainson, W.A., 1840
Species

See text.

Synonyms

[1]

  • Marginella (Gibberula) Swainson, 1840
  • Granula Jousseaume, 1875
  • Kogomea Habe, 1951
  • Dentiginella Laseron, 1957
  • Epiginella Laseron, 1957
  • Lataginella Laseron, 1957
  • Phyloginella Laseron, 1957
  • Vetaginella Laseron, 1957
  • Diluculum Barnard, 1962

Gibberula is a genus of minute sea snail, a marine gastropod mollusk or micromollusk in the family Cystiscidae, previously placed in the family Marginellidae, the margin shells or marginellids.[1]

(Note: Gastropod taxonomy has been in flux for many years. This is especially true currently, because of new research in molecular phylogeny. Because of all this ongoing change, different reliable sources can yield very different classifications, especially within certain poorly understood groups.)

The type species of the genus Gibberula Swainson, 1840 is G. zonata Swainson.

Other genus-group names are available for small shells resembling Gibberula. These include Granula Jousseaume, 1875 and Kogomea Habe, 1951. They are distinguished from Gibberula only on the basis of smaller size and other rather tenuous conchological differentiations.

Shell description

The shell of this genus is 1.5 to 10 mm in length, ovoid, stout, with a small, low spire. The outer lip is thickened but without an external varix. It is usually denticulated inside. The columella has several plaits on a thickened rim, decreasing in size towards the posterior end. The siphonal canal is distinctly notched.

Animal

Head and foot

The head is deeply divided in two. There are two short cephalic tentacles and two small anterior lobes. The eyes are a short distance behinde the tentacles. The mouth is provided with an extensible proboscis. The foot is only slightly longer than the shell when extended. In some species, the sole lies flat on the substrate when the animal is crawling. Others have the edge of the propodium raised, developed as parapodia which fit the head/tentacles in the manner of many tectibranchs.
Color pattern of the head and foot is a useful taxonomic character in all the species.

Mantle

The mantle does not extend over the shell during normal activity. A tongue shaped, translucent lobe may be seen on the left side in some instances. The internal mantle is usually visible through the shell. It may be brightly coloured in the smaller species with a featureless, translucent shell, and its pattern is then continued into the spire over the visceral mass. The siphon is short and inconspicuous, often bordered by a small pad.

Reproduction

All species of marginellids have a direct development without a planktonic phase.

Species

The separation between the genera Persicula and Gibberula is not clearcut and currently follows a rather arbitrary criterion where the large species with (usually with complex colour pattern) are placed in Persicula and the smaller species with a banded or uniform colour pattern in Gibberula, leaving in between many ambiguous species. To date (2010) there is no phylogenetic analysis behind the current generic placements.[1]

Species brought into synonymy

References

  1. ↑ 1.0 1.1 1.2 Bouchet, P.; Gofas, S. (2011). Gibberula Swainson, 1840. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=137881 on 2011-10-10
  2. ↑ The small marginelliform gastropods from Ghana (Neogastropoda, Cysticidae). Argonauta, 11(1) 1997: 3-12
  3. ↑ Studies on West Indian marine molluscs. 13. The malacological taxa of Gordon W. Nowell-Usticke
  4. ↑ Three new species of marginellas from the Dakar region (Senegal), (Gastropoda: Marginellidae). Conchiglia, 27(275), April–June 1995: 55-61
1999. Descripción de nuevas marginelas (Mollusca: Neogastropoda: Marginellidae) de Cuba y del Caribe de Costa Rica y Panamá. Avicennia 10/11:165-176.
2000. Descripción de un género y once especies nuevas de Cystiscidae y Marginellidae (Mollusca: Neogastropoda) del Caribe de Costa Rica. Aviccenia 12/13:95-114.
2002. Nuevas especies de margineliformes de Cuba, Bahamas y el Mar Caribe de Costa Rica. Avicennia 15:101-128.
1987. Le Genre Gibberula (Marginellidae) en Mediterranee. Atti del II Congresso Societa Italiana di Malacologia. No. 23, 113-119
1989. The Marginellidae of Angola: The genus Gibberula. Journal of Conchology Vol. 33 (1989), No. 3, 109-139