The Lower Permian Plocezyga (Hyphantozyga) matanensis, from Pan & Erwin (2002).

Belongs within: Caenogastropoda.

Plocezyga was a Lower Carboniferous to Middle Permian genus of high-spired gastropods. Originally included in the genus Hemizyga, the genera had to be separated after it was established that the type species of Hemizyga was not representative of the majority of species in that genus (Hoare & Sturgeon 1980a, b). Plocezyga is a member of the family Pseudozygopleuridae which is distinguished by the form of the protoconch: smooth on the first 1.5 whorls, followed by collabral ornament on the second to fourth walls, with the ornamented whorls slightly swollen (Knight et al. 1960).

Characters (from Knight et al. 1960): Conch with both collabral and spiral ornament; labral sinus very shallow or absent.

<==Ploceozyga Hoare & Sturgeon 1980 PE02
    |--P. (Hyphantozyga Knight 1930) PE02
    |    |--P. (*H.) gracilis (Knight 1930) [=Hemizyga (Hyphantozyga) gracilis] PE02
    |    |--P. (H.) fenestrata (Hoare & Sturgeon 1980) [=Gamigyza (H.) fenestrata] PE02
    |    `--P. (H.) matanensis (Pan & Yu 1993) [=Hemizyga (Hyphantozyga) matanensis] PE02
    `--P. (Plocezyga Knight 1930) PE02
         |--P. (P.) cancellata (Mark 1912) PE02
         |--P. (P.) delicata Hoare & Sturgeon 1980 PE02
         |--P. (P.) lineata Hoare & Sturgeon 1980 PE02
         |--P. (P.) ornatissima Hoare & Sturgeon 1980 PE02
         |--P. (P.) varica Pan & Erwin 2002 PE02
         `--P. (P.) yunnanensis Pan & Erwin 2002 PE02

*Type species of generic name indicated


Hoare, R. D., & M. T. Sturgeon. 1980a. The Pennsylvanian pseudozygopleurid gastropod genus Gamizyga n.gen. from Ohio and West Virginia. Journal of Paleontology 54 (1): 159-187.

Hoare, R. D., & M. T. Sturgeon. 1980b. Gamizyga: a correction. Journal of Paleontology 54 (5): 1101.

Knight, J. B., R. L. Batten, E. L. Yochelson & L. R. Cox. 1960. Supplement: Paleozoic and some Mesozoic Caenogastropoda and Opisthobranchia. In: Moore, R. C. (ed.) Treatise on Invertebrate Paleontology pt I. Mollusca 1. Mollusca—General Features. Scaphopoda. Amphineura. Monoplacophora. Gastropoda—General Features. Archaeogastropoda and some (mainly Paleozoic) Caenogastropoda and Opisthobranchia pp. I310-I331. Geological Society of America, Inc. and University of Kansas Press.

[PE02] Pan, H.-Z., & D. H. Erwin. 2002. Gastropods from the Permian of Guangxi and Yunnan Provinces, south China. Journal of Paleontology 76 (Memoir 56): 1-49.

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