Aillya

from Wikipedia, the free encyclopedia
Aillya
Systematics
Superordinate : Heterobranchia
Order : Lung snails (pulmonata)
Subordination : Land snails (Stylommatophora)
Superfamily : Aillyoidea
Family : Aillyidae
Genre : Aillya
Scientific name of the  superfamily
Aillyoidea
Baker , 1955
Scientific name of the  family
Aillyidae
Baker , 1955
Scientific name of the  genus
Aillya
Odhner , 1927

Aillya is the only genus of the family Aillyidae from the suborder of land snails (Stylommatophora); the Aillyidae are in turn the only family of the superfamily Aillyoidea . They are half-slugs whose thin-walled shell is covered by two mantle lobes. The two (or three?) Species are native to West Africa.

features

The two species of the genus Aillya and the family Aillyidae have egg-shaped or elliptical shells that are covered by two enlarged mantle lobes. The 2.5 to 3.5 whorls increase very quickly, so that the mouth height reaches almost 90% of the total height. There is no navel. The height is up to 7.3 mm, the width up to 5 mm. The adult animals can no longer withdraw into the housing. The mouth is egg-shaped with thin, simple edges. The whitish-opaque or colorless shell is thin, glass-like, very fragile and translucent. The surface has a pearly sheen. The embryonic shell is covered with very small pustules in spiral rows. The postembryonic whorls show fine radial lines that are most distinct at the lower end. The two jacket lobes almost completely cover the housing; only a little behind the middle is a small, narrow strip uncovered. The front flap extends forward far beyond the housing and also covers the head. Only the antennae protrude from this structure. The rear border is deeply booked. The posterior lobe tapers to the rear when viewed from above in an acute triangular shape, is significantly longer than the housing, but does not reach the end of the tail. The triangular end is lifted from the body and ends in a cone-like point. The front end is curved forward. A crescent-shaped gap thus remains free between the front edge of the rear mantle flap and the rear edge of the front mantle flap, through which the housing is still visible. Both jacket flaps are laterally connected to each other at the lower end of the flaps. The foot has a short caudal process, but no caudal pore. The sole of the foot has transverse wrinkles. The hermaphroditic gland consists of numerous, elongated acini , which are concentrated in a few clusters. The hermaphroditic duct is tortuous and forms a loop on the inside of the albumin gland. The egg ladder (spermoviduct) is very short. The prostate consists of long, tightly packed acini. In contrast, the vas deferens is very long and enters the penis near the apex. The flagellum is short and thick and has an axial thread inside. The inner wall of the epiphallus has depressions. The large penis has two chambers on the inside, which are separated from each other by rounded folds. There are a few short, elongated pillar structures in the chambers. The penile retractor muscle attaches to the epiphallus / flagellum transition. The free fallopian tube is rather short, but the vagina is expanded and the inner walls are filled with longitudinal folds. The stem of the seminal vesicle is very short, the vesicle itself ovoid. The calcareous-shell eggs are 1 mm in diameter and very large in relation to the size of the adult animal.

Geographical distribution and habitat

The two species are so far only known from Cameroon , Sierra Leone , Nigeria and Bioko (formerly "Fernando Póo").

Systematics

The Aillyidae family currently contains only one genus with two species:

Possibly there is a third species that can be added to the genus Aillya , "Succinea" catena Spence, 1925 from Cameroon. The species could also be conspecific with Aillya camerunensis .

The genus Prestonella Connolly, 1929 was put by Schileyko with question marks to the family Aillyidae. According to the more recent anatomical and molecular genetic studies by Herbert & Mitchell (2009), however, it belongs to the Bulimulidae family .

supporting documents

literature

  • Philippe Bouchet, Jean-Pierre Rocroi: Part 2. Working classification of the Gastropoda . In: Malacologia , Vol. 47, 2005, 239-283, Ann Arbor ISSN  0076-2997
  • Nils Hjalmar Odhner: Aillya camerunensis, n. Gen., N. Sp., An African bulimuloid snail. In: Arkiv för Zoologi, Volume 19A, No. 20, 1927, pp. 1-16.
  • Anatolij A. Schileyko: Treatise on Recent Terrestrial Pulmonate Molluscs, Part 3: Partulidae, Aillyidae, Bulimulidae, Orthalicidae, Megaspiridae, Urocoptidae. In: Ruthenica, Supplement , Volume 2, No. 3, 1999, pp. 263-436, Moscow ISSN  0136-0027
  • Adolf Zilch: Gastropoda. Part 2: Euthyneura. In: Handbuch der Paläozoologie, Volume 6, 1960, pp. 1–834, Berlin, Verlag von Gebrüder Borntraeger (p. 520)

Individual evidence

  1. ↑ Eronwon Omoregie: Land Snail Species Richness in a Cocoa Agro-Forest in Ile-Oluji, Ondo State, Nigeria. In: The Zoologist , Volume 10, 2012, pp. 40-47 online
  2. ↑ Horace Burrington Baker, "Heterurethrous and aulocopod". In: The Nautilus , Volume 68, No. 4, 1955: 109-112 Online at www.archive.org .
  3. ^ A b Matthew William Kemble Connolly: XXI. — Notes on African non-marine Mollusca, with descriptions of many new species (concluded). In: The Annals and Magazine of Natural History , 10th Series, Volume 3, 1929, pp. 165-178.
  4. ↑ David G. Herbert, Andrew Mitchel: Phylogenetic relationships of the enigmatic land snail genus Prestonella: the missing African element in the Gondwanan superfamily Orthalicoidea (Mollusca: Stylommatophora). In: Biological Journal of the Linnean Society , Volume 96, 2009, pp. 203-221
  5. ^ David G. Herbert: Revision of the genus Prestonella (Mollusca: Gastropoda: Orthalicoidea: Bulimulidae sl): a distinctive component of the African land snail fauna. In: African Invertebrates, 48, 2007, 1-19