Strobilopsidae

Strobilopsidae
Engraving showing an apertural view of a shell of Strobilops labyrinthicus
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
(unranked): clade Heterobranchia

clade Euthyneura
clade Panpulmonata
clade Eupulmonata
clade Stylommatophora
informal group Orthurethra

Superfamily: Pupilloidea
Family: Strobilopsidae
Wenz, 1915
Genera

See text

Synonyms

Strobilidae Jooss, 1914 (inv.)

Strobilopsidae is a family of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the superfamily Pupilloidea.

Taxonomy

The Strobilopsidae family is classified within the informal group Orthurethra, itself belonging to the clade Stylommatophora within the clade Eupulmonata (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005).[1]

The family Strobilopsidae has no subfamilies according to the taxonomy of the Gastropoda by Bouchet & Rocroi (2005).

Some authorities place the family Spelaeodiscidae as a subfamily (Spelaeodiscinae) of the Strobilopsidae.[2][3]

Genera

Genera within the family Strobilopsidae include:

Shell description

The shell is trochiform, dome-shaped or discoidal and umbilicate. The shell has from 4½ to 6 slowly enlarging whorls. The aperture is small, oblique, with armature of 2 or 3 parietal lamellae and several deeply placed basal folds, all growing continuously from an early neanic stage. The peristome is more or less thickened and expanded, the ends of the lip remote, joined by a parietal callus.[5]

The shell, aside from its helicoid shape (not a character of great importance), differs from all Pupillidae in the arrangement of the lamellae and baso-palatal folds. In multidentate Pupillidae the five primary teeth are always recognizable while in Strobilops only the main parietal lamella and the columellar lamella can certainly be said to correspond, and these are found in so many other land shells that their occurrence is not especially significant. It is possible, however, that upper and lower palatal folds of Pupillidae are represented by teeth 5 (the most right basal tooth) and 2 (second left basal tooth), and the basal fold by tooth 1 (the most left basal tooth).[5]

By the accelerated lamellae and folds of the shell, which appear early in the neanic stage, Strobilops resembles various Tornatellininae (within Achatinellidae). In that family both parietal and palatal folds or laminae are sometimes present in the neanic stage. Various pupillid genera also, such as Orcula (Orculidae) and Lauria (Lauriidae), have apertural armature during the neanic stage. Orcula has spiral parietal and columellar lamellae but no basal or palatal folds. Lauria has basal folds, but they are spaced, transverse barriers, wholly unlike the adult basal or palatal armature of the species, and differing equally from the folds of immature Strobilops, which from their inception appear to develop continuously into those of the adult shell. It appears likely that the acceleration or early appearance of apertural armature in Tornatellininae, Orcula, Lauria and Strobilops has been independent in the four groups, and is not indicative of direct relationship between any of them.[5]

Anatomy

The urethra lies very near the last part of the intestine.[5]

Digestive system: The jaw has numerous ribs. Radula with tricuspid central tooth with square basal plate, as large as the bicuspid laterals, the marginals multicuspid.[5]

Reproductive system: Ovotestis forms two groups of follicles. Penis is continued in a long epiphallus and bears a long appendix, with swollen basal and distal divisions, the penial retractor bifurcate, one branch inserted on the epiphallus, the other on the base of the appendix (distally it attaches to the right ocular retractor, according to G. Dallas Hanna).[5]

By the structure of the male organs Strobilops resembles Vallonia, Pupilla, Lauria, the Achatinellidae, and some other groups are similar in having a bifurcate penial retractor and a long, tripartite appendix. If G. Dallas Hanna is right in stating that the penial retractor is a branch of the right ocular band, this is an important difference from any known Orthurethra. The mouth parts do not differ materially from some Pupillidae.[5]

Fossil distribution

Strobilopsidae appeared in the Upper Eocene of western Europe in several species having all the external characters of the genus Strobilops, and though the internal structure has not been worked out (in 1927),[5] it is safe to assume that they are closely related to the well-known Oligocene forms following them. In Europe this genus continued in numerous species into the Pliocene, the last one in the Upper Pliocene (Astian stage) of Piedmont.[5]

In late Cretaceous beds there are various forms described as Helix, or under the names Obbinula and Pseudostrobilus, which certainly have some of the characters of Strobilops. All are larger than any Strobilops.[5]

References

This article incorporates public domain text originating from the USA from the reference [5] (1927 work without copyright notice).

  1. 1 2 Bouchet P.; Rocroi J.-P.; Frýda J.; Hausdorf B.; Ponder W.; Valdés Á. & Warén A. (2005). "Classification and nomenclator of gastropod families". Malacologia: International Journal of Malacology. Hackenheim, Germany: ConchBooks. 47 (1-2): 1–397. ISBN 3-925919-72-4. ISSN 0076-2997.
  2. ↑ Strobilopsidae. Fauna Europaea, accessed 20 April 2010.
  3. ↑ Strobilopsidae. MollBase, accessed 20 April 2010.
  4. 1 2 (Japanese) Minato H. (1982). 日本のクチミゾガイ類. "Eostrobilops and Enteroplax from Japan (Strobilopsidae)". 日本貝類学会研究連絡誌 The Chiribotan. CiNii.
  5. 1 2 3 4 5 6 7 8 9 10 11 Pilsbry H. A. (1927). Manual of Conchology, structural and systematic, with illustrations of the species. Second series: Pulmonata. Volume 28. Geographic Distribution of Pupillidae; Strobilopsidae, Valloniidae and Pleurodiscidae. Conchological department Academy of Natural Sciences of Philadelphia, Philadelphia. 1-48.

Further reading

Wikimedia Commons has media related to Strobilopsidae.
This article is issued from Wikipedia - version of the 8/18/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.