Anatoma argentinae
| Anatoma argentinae | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Subclass: | Vetigastropoda |
| Order: | Lepetellida |
| Superfamily: | Scissurelloidea |
| Family: | Anatomidae |
| Genus: | Anatoma |
| Species: | A. argentinae
|
| Binomial name | |
| Anatoma argentinae (Zelaya & Geiger, 2007)
| |
| Synonyms[1] | |
| |
Anatoma argentinae is a species of small deep sea sea snail, a marine gastropod mollusc in the family Anatomidae.[1] Commonly classified as part of the "little slit shells," this micromollusc is a significant component of the deep-water benthic communities within the South Atlantic.[2]
Taxonomy and Phylogeny
The species was first identified in 2007 by Diego G. Zelaya and Daniel L. Geiger during an extensive study of Sub-Antarctic and Antarctic micromollusca.[3] It was initially placed in the genus Thieleella based on the presence of strong axial sculpture on the protoconch and teleoconch.[3]
In 2012, Geiger’s monograph on the superfamily Scissurelloidea revised the group, synonymizing Thieleella with Anatoma after phylogenetic analysis demonstrated that the sculptural traits previously used to distinguish the two genera were homoplastic or intergraded across species.[2][4]
Description
The shell of Anatoma argentinae is relatively robust compared to other bathyal anatomids.
- Shell Dimensions: The shell can reach a diameter of up to 5 mm, which is large for the family.[2] The height-to-width ratio typically indicates a slightly depressed trochiform shape.[3]
- Sculpture: The teleoconch consists of approximately 2.5 to 3 whorls. It features prominent, regularly spaced axial ribs (approximately 40–50 on the last whorl) intersected by finer spiral threads, creating a clathrate or reticulated appearance.[3][5]
- Selenizone: The selenizone (the track left by the slit) is situated at the periphery. It is bordered by sharp, elevated flanges. The slit itself is open for about one-eighth of the circumference of the last whorl.[2][3]
- Protoconch: The protoconch measures approximately 200–250 μm and lacks a distinct varix, suggesting a non-planktotrophic (lecithotrophic) larval development, which is common in deep-sea gastropods to ensure local recruitment.[2][6]
Distribution and Bathymetry
Anatoma argentinae is primarily found in the southwestern Atlantic Ocean.
- Geographic Range: Type specimens were recovered from the Argentine Basin and near the South Georgia rise.[3][7]
- Depth Range: The species is strictly bathyal, with recorded occurrences between 1,000 and 2,500 meters deep.[2]
- Habitat: It occurs on the continental slope, specifically in areas dominated by fine-grained terrigenous sediments and biogenic oozes.[3][8]
Ecology
As a member of the Vetigastropoda, A. argentinae possesses rhipidoglossate radula, characterized by numerous marginal teeth used for sweeping up organic detritus and diatoms.[8][2] In the nutrient-poor bathyal zones, they function as opportunistic feeders on the biofilm layer of the sediment surface.[9]
References
- ^ a b "Anatoma argentinae". World Register of Marine Species. Retrieved 2026-03-04.
- ^ a b c d e f g Geiger, D.L. (2012). Monograph of the Little Slit Shells. Santa Barbara Museum of Natural History. ISBN 978-0-93649-443-2.
- ^ a b c d e f g Zelaya, D.G.; Geiger, D.L. (2007). "Species of Scissurellidae and Anatomidae from Sub-Antarctic and Antarctic waters". Malacologia. 49 (2): 393–443. doi:10.4002/0076-2997-49.2.393.
- ^ Geiger, D.L. (2003). "Phylogenetic assessment of characters proposed for the generic classification of Recent Scissurellidae". Molluscan Research. 23: 21–83.
- ^ Harasewych, M.G. (2002). "The deep-sea Atlantic Scissurellidae". The Nautilus. 116.
- ^ Marshall, B.A. (1993). "The Scissurellidae of the New Zealand region". The Veliger. 36: 285–298.
- ^ Linse, K. (2002). "The marine Bivalvia and Gastropoda of the Magellan Region". Scientia Marina. 66.
- ^ a b Sasaki, T. (1998). "Comparative anatomy and phylogeny of the Recent Archaeogastropoda". The University Museum, The University of Tokyo, Bulletin. 38.
- ^ Hickman, C.S. (1988). "Archaeogastropod evolution, phylogeny and systematics". Malacological Review.