Ammonicera minortalis
| Ammonicera minortalis | ||||||||||||
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Ammonicera minortalis (from Rolán (1992): Figures 10, 11, 13, 15). 100 μm scale |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Ammonicera minortalis | ||||||||||||
| Rolán , 1992 |
Ammoniceras minortalis is a living in the sea snails art from the family of omalogyridae that the Heterobranchia is expected. Its planispiral, ammonite-like housing has a diameter of only 0.34 to 0.46 millimeters. It is currently (November 2015) the smallest known living snail species.
features
The tightly wound, planispiral and very small cases measure 0.34 to 0.46 mm in diameter (0.2 to 0.4 mm according to Emilio Rolán) and about 0.13 mm in height in the adult stage. The housing has up to 2.6 turns. Of these, the Protoconch, with a diameter of 120 to 135 μm, has around 1.3 turns (a three-quarter turn according to Rolán). It has an ornamentation consisting of a very strong longitudinal rib on each side, which is accompanied inwardly by three to four spiral longitudinal lines. A strong reticulate pattern is formed on the periphery.
The Teleoconch has 1.3 turns (1 to 1.5 according to Rolán). The turns are rounded in cross section and well rounded at the periphery. You have a sculpture consisting of strong radial ribs sitting on the sides at approximately the same intervals, a total of around 15 to 19 (13 to 17 according to Rolán) ribs on one turn. They flatten towards the inside and the periphery. There are only fine strips of growth between the ribs. The periphery is almost smooth with very fine growth strips that are slightly thickened at irregular intervals. Occasionally there are also some spiral lines. The mouth is rounded in plan with a thin outer lip and a sharp edge. The mouth plane is perpendicular to the winding axis. There are no folds or pits on the spindle.
The shell is dark brown, with the exception of the shell near the mouth; here the shell is light brown. The housing surface is shiny. The head foot is translucent to almost transparent. The animal glides quickly on a short foot. The blunt propodium is very mobile. The housing is carried almost vertically during the movement. The horny operculum is transparent and sits on the back of the foot. It also serves as a support for the case. Two finger-shaped tentacles sit on the head and are carried slightly bent upwards. The eyes near the base of the tentacles are black.
Similar species
Ammonicera japonica Habe, 1972 has a similar housing, but it is significantly larger. Also Ammonicera rota (Forbes & Hanley, 1853) has a similar Adult housing Here, however, draw the ribs on the periphery, and the protoconch is different. The adult housing is also larger.
Geographical distribution and habitat
The species has so far only been found in the shallow waters around Cuba , the Florida Keys, and the Yucatan Peninsula . Localities on the north coast of Cuba are: Baracoa , Comodoro and El Salado . On the south coast they were found in the following locations: Cayo Diego Pérez , Cayo Marias , Cayo Cantiles and in the Canarreos Archipelago .
The animals live there in shallow water at a depth of 3 to 20 m. The size of the Protoconch and the lack of a Protoconch II suggest that no larval stage living in free water is formed. The development takes place via yolk-rich eggs from which a finished young animal hatches.
Taxonomy
The species name, from Latin minor = "small" and talis = "so constituted", indicates the extremely small adult size of the shell (compared to the majority of other snail species). The holotype comes from the shallow water (4 m water depth) off Baracoa in eastern Cuba. It is kept in the Museo Nacional de Ciencias Naturales in Madrid under the number MNCN 15.05 / 6794. Paratypes from the same locality have also been deposited in the Muséum national d'histoire naturelle in Paris , the Natural History Museum in London , the American Museum of Natural History in New York and the Zoological Museum in Amsterdam .
Reception in the press
Although the species is now recognized as the smallest species of snail in the world, at the time of its first publication it received no attention in the popular scientific press. The author of the taxon did not explicitly point this out in his publication. The follow-up publication, whose title "Notes on the Smallest Living Gastropod in the United States and Comments on Other Species of Omalogyridae (Heterobranchia)" explicitly indicates the small size of the case, did not find media coverage. It was only with the publication of the (then) smallest land snail in the world Angustopila dominikae in August 2015 that Ammonicera minortalis z. Sometimes mentioned in the popular scientific press. However, it was often overlooked in other publications that Angustopila dominikae is not the smallest species of snail at all, but "only" the smallest land snail. Even after the publication of the now smallest land snail Acmella nana in November 2015, this difference was often overlooked in the popular scientific press.
supporting documents
literature
- Rüdiger Bieler, Paula M. Mikkelsen: Notes on the Smallest Living Gastropod in the United States and Comments on Other Species of Omalogyridae (Heterobranchia). Nautilus, 111 (1): 1-12, 1998 PDF
- Emilio Rolán: The family Omalogyridae GO Sars, 1878 (Mollusca, Gastropoda) in Cuba with description of eight new species. apex 7 (2): 35-46, 1992 online at www.biodiversitylibrary.org
