Taxonomy
- Kingdom: Animalia
- Phylum: Mollusca
- Class: Gastropoda
- Subclass: Caenogastropoda
- Order: Littorinimorpha
- Superfamily: Rissooidea
- Family: Rissoidae
- Genus: Manzonia Brusina, 1870
- Species: Manzonia geometrica Beck & Gofas, 2007
Authority: Described by H.H. Beck and S. Gofas in 2007.
Common name: Not widely used; the species is a minute marine snail (micromollusc).
Description
Manzonia geometrica is a very small sea snail, with adult shells ranging from approximately 1.6 mm to 2.3 mm in height. The shell possesses a protoconch of about 1.25 whorls and a teleoconch of roughly three whorls. Distinctive morphological features include:
- A strong adapical keel on the protoconch.
- A pronounced median keel on the teleoconch that gives the shell an unmistakable profile.
- Flat spiral cords that are broader than the interspaces, forming a characteristic sculpture.
- An outer lip that is opisthocline (sloping backward) and thickened by an external rim that gently slopes toward the adjacent body whorl surface.
The species exhibits direct (non‑planktotrophic) larval development, indicated by a paucispiral protoconch.
Habitat and Distribution
Manzonia geometrica is a marine species inhabiting seamount environments in the Northeast Atlantic. Recorded occurrences include:
- Ampère Seamount (approximately 35°03′19″ N, 12°54′42″ W) where it is moderately common at depths of 130–325 m.
- Seine Seamount, where it is rarer and found at depths of 165–190 m.
The species lives in marine benthic zones associated with hard substrates typical of seamounts.
Ecology
As a micromollusc, M. geometrica likely grazes on microalgae or biofilm covering the substrate, though specific ecological interactions have not been extensively documented.
References
- Wikipedia contributors. “Manzonia geometrica.” Wikipedia, The Free Encyclopedia. https://en.wikipedia.org/wiki/Manzonia_geometrica (accessed 2026‑05‑19).
- World Register of Marine Species (WoRMS). “Manzonia geometrica Beck & Gofas, 2007.” https://www.marinespecies.org/aphia.php?p=taxdetails&id=345742 (accessed 2026‑06‑02).
Notes
- The species was formally described in the journal Journal of Natural History (Gofas S., 2007) as part of a revision of Rissoidae from Northeast Atlantic seamounts.
- No common vernacular name is recorded; references to this taxon are generally confined to scientific literature and biodiversity databases.
