Thyrophorella thomensis
Thyrophorella thomensis is a species in the suborder of terrestrial snails ( gastropod ). It is the only species of the genus Thyrophorella, which in turn is the sole genus of the family Thyrophorellidae. The species is endemic to the island of São Tomé.
Features
The housing is linksgewunden and niedrigkegelig. They reach 9 mm in diameter and 4 mm in height. You have first a weak side shoulder, which is on the final turn to a sharp edge. The turns are very convex below; especially the final turn takes down greatly in thickness. Overall, only about three turns are formed.
The shell is relatively thin and translucent. The color varies from yellowish to horn color. The embryo Alwin Dungen are provided with faint radial lines, which pass on the following turns into fine, irregularly curved radial striae. The estuary is semi-circular and is almost perpendicular to the coil axis. The mouth edges are sharpened easily and sharp. The upper edge is straight, the lower edge curved semicircular. The opening can be closed with a kind of operculum. However, it is not homologous to the other screw operculum groups, but is an extension of the upper part of the peristome. With this, it is connected by a flexible zone consisting of periostracum. This resulting secondary mechanism to close the housing is unique within the auger. The growth of the housing seems to go in spurts on. The operculum is formed only in phases in which the housing is growing little. In periods of strong growth, it is calcified, integrated into the growing body and the animal has a short time no closure lid. The lid can not be moved by muscle power, but falls upon retraction of the animal into the housing and is pressed when the animal comes forth again out of the housing. The umbilicus is wide and open.
In the male part of the reproductive system, the penis is relatively long with a bottom- end of the penis retractor muscle. In the female part of the vagina, the atrium is heavily bloated, very tight. The stem of the spermathecae is very short.
Geographical distribution, occurrence and life
The species is found only on the island of São Tomé in the Gulf of Guinea in the South Atlantic. Since the last detailed description from 1895 succeeded only in 1993, a proof of this kind could be photographed as a live animal. Little is known about the way of life. The specimens found in 1882 were found at Monte Café in around 800-900 m height, from 1895 at an altitude of about 1000 m.