Monadenia (animal species)

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Monadenia
Monadenia fidelis (JE Gray, 1834)

Monadenia fidelis (JE Gray, 1834)

Systematics
Superordinate : Heterobranchia
Order : Lung snails (pulmonata)
Subordination : Land snails (Stylommatophora)
Superfamily : Helicoidea
Family : Monadeniidae
Genre : Monadenia
Scientific name of the  family
Monadeniidae
Nordsieck , 1987
Scientific name of the  genus
Monadenia
Pilsbry , 1896

The genus Monadenia is the only genus of the family Monadeniidae from the subordination of land snails (Stylommatophora). It occurs only in western North America from Alaska to California . A total of almost 20 species, subspecies and color variants are described.

features

The housings are mostly flat conical to flattened. The skin is only moderately thick to rather thin. The last contact often forms a keel on the outer edge. In the adult stage, the end of the last contact often falls very clearly off the convoluted level. The color of the case is usually light to dark brown, often with a dark spiral band over the periphery of the enclosure. It is bordered by lighter areas below and above. But there are also cases that are uniformly yellowish or blackish. The surface of the embryonic housing or the embryonally formed passageways is densely grained. The later turns have fine radial stripes that can intersect with fine spiral stripes. The mouth is oval and always at an angle to the axis of the coil. The lower edge is often bent over. The navel is narrow and mostly open. The jaws show strong ribs. The genus or family is characterized by the absence of the diverticulum, a feature in the male part of the sexual apparatus. The animals only have one love arrow , which is double-edged.

Love arrow from Monadenia fidelis

Occurrence, way of life and distribution

The species of the genus or family live exclusively in the coastal areas in western North America. The distribution area ranges from Alaska in the north to the Bay of San Francisco in California. At the height of the San Francisco Bay, the occurrence extends inland to Mariposa County .

Systematics

Schileyko (2005) places the family in the superfamily Xanthonychoidea, which, however, is not recognized by Bouchet & Rocroi (2005). Nordsieck (2006) also points out that the Xanthonychidae family is polyphyletic. The latter authors therefore place them in the superfamily Helicoidea . The family Monadeniidae currently only contains one genus, which Schileyko (2005) divides into three subgenus:

  • Family Monadeniidae Nordsieck, 1987
    • Genus Monadenia Plsbry, 1895
      • Subgenus Monadenia (Monadenia) Pilsbry, 1895
      • Subgenus Monadenia (Shastelix) Roth, 1981
      • Subgenus Monadenia (Corynadenia) Berry, 1940

Species without assignment to a specific subgenus

Phylogeny

According to Koene and Schulenburg (2005), the three North American families Humboldtianidae , Helminthoglyptidae and Monadeniidae are more closely related and form a monophylum, which is opposite to the helicoid snails (Helicidae). Within the Monophylum, Humboldtianidae and Helminthoglyptidae form a Monophylum, which is the sister group of the Monadeniidae.



 Helicidae 


   



 Helminthoglyptidae 


   

 Humboldtianidae 



   

 Monadeniidae 





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Individual evidence

  1. ↑ Schileyko, p. 1695

literature

  • Philippe Bouchet & Jean-Pierre Rocroi: Part 2. Working classification of the Gastropoda . Malacologia, 47: 239-283, Ann Arbor 2005 ISSN  0076-2997
  • Joris M. Koene and Hinrich Schulenburg: Shooting darts: co-evolution and counter-adaptation in hermaphroditic snails. BMC Evolutionary Biology, 5:25, 13 pages, 2005 doi : 10.1186 / 1471-2148-5-25
  • Hartmut Nordsieck: Higher classification of the Helicoidea and the molecular analyzes of their phylogeny . 2006 PDF (server currently not accessible)
  • Anatolij A. Schileyko: Treatise on Recent terrestrial pulmonate molluscs, Part 12 Bradybaenidae, Monadeniidae, Xanthonychidae, Epiphragmophoridae, Helminthoglyptidae, Elonidae, Humboldtianidae, Sphincterochilidae, Cochlicellidae. Ruthenica, Supplement 2 (10): 1627-1763, Moscow 2005 ISSN  0136-0027

Web links

Commons : Monadenia  - collection of images, videos and audio files