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Microstelma

Gastropoda - Rissoidae

Taxonomy
Microstelma was named by Adams (1861) [Sepkoski's age data: T Mi-l R Sepkoski's reference number: 650]. It is extant.

It was assigned to Rissoininae by Ponder (1984); to Rissoidae by Todd (2001); and to Neotaenioglossa by Sepkoski (2002).

Synonyms
Synonymy list
YearName and author
1861Microstelma Adams
1867Amaurella Adams
1867Crepitacella Guppy p. 500
1873Dolophanes Gabb p. 272
1928Crepitacella Woodring p. 360
1972Crepitacella Perrilliat p. 26
1984Microstelma Ponder p. 97
2001Microstelma Todd
2002Microstelma Sepkoski, Jr.

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Protostomia
Spiralia
Schizocoela
phylumMollusca
RankNameAuthor
classGastropodaCuvier 1797
superorderHypsogastropoda(Ponder and Lindberg 1997)
infraorderLittorinimorphaGolikov and Starobogtov 1975
Discopoda(Fischer 1884)
superfamilyRissooideaGray 1847
familyRissoidaeGray 1847
genusMicrostelmaAdams 1861

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Diagnosis
ReferenceDiagnosis
W. F. Ponder 1984Shell: of medium to large size, ovateconic, with narrow to absent umbilical chink; weak to moderate axial ribs and weak spiral striae; axial ribs (if present) do not extend over base. Base with prominent fasciole. Aperture with simple peristome, prominently channelled and angled anteriorly and posteriorly. Outer lip opisthocline, with weak varix externally; inner lip rather narrow (Figs 67; 68). Protoconch conical, multispiral or paucispiral (about 3 Yz whorls in M. melanoides, about 2 in M. cepula and M.japonica, and I Yz in M. daedala), micro sculpture absent (known only in M. japonica, Fig. 1420).