Genotype: Diplotrypa infida Ulrich
Taxonomic History (Nickles & Bassler, 1900)
- 1879 Diplotrypa (in part) Nicholson, Paleozoic Tabulate Corals, p. 312.
- 1881 Diplotrypa (in part) Nicholson, Genus Monticulipora, pp. 101, 155.
- 1882 Diplotrypa (in part) Ulrich, Jour. Cincinnati Soc. Nat. Hist., V, p. 153.
- 1883 Diplotrypa (in part) Foord, Contr. Micro-Pal. Cambro-Sil., p. 13.
- 1890 Diplotrypa (in part) Ulrich, Geol. Sur. Illinois, VIII, p. 378.
- 1893 Mesotrypa Ulrich, Geol. Minnesota, III, p. 257.
- C5 Sequence (Saluda, Lower Whitewater, Liberty)
- C4 Sequence (Arnheim)
Identification in Hand Sample:
- Zoarium Morphology: vylindrical with a few curved, flat or sloping diaphragms
- Zoecia: prismatic or cylindrical with oblique and sometimes funnel-shaped diaphragms
- Mesozooids: polygonal with numerous flat diaphragms
- Monticules: n/a
- Maculae: n/a
Holland (UGA Strat Lab, 2013):
- Mesotrypa is typically hemispherical, conical, discoidal, or encrusting. Zooecia cylindrical, with few curved, flat, or sloping diaphgragms. Zooecia separated by polygonal mesozooids with numerous flat diaphgragms. Styles with clear cores are well developed.
- Type species.— Diplotrypa in/Ida Ulrich, 1886, p. 88, subsequently designated by Ulrich (1893, p. 257); Decorah Shale of current usage, Middle Ordovician, Minnesota.
- Remarks.— The two taxa assigned to Mesotrypa conform to the emended concept for the genus Mesotrypa by Ross (1970a, p. 365) that is followed herein.
- Zoarium hemispheric, conical, or discoidal, generally free, with an epitheca on the under surface; zooecia prismatic or cylindrical, with oblique and sometimes funnel-shaped diaphragms, which are probably modified cystiphragms; zooecia more or less separated by angular mesopores, which become smaller with age, and are intersected by numerous diaphragms; acanthopores generally present, sometimes of large size.
- Genotype.—Diplotrypa infida Ulrich. Middle Ordovician (Black River) of Minnesota.
- This genus includes several groups of species, all of which agree in having a massive zoarium of zooecial tubes crossed by curved diaphragms, and of closely tabulated mesopores with rather straight walls. The typical group of the genus includes species with numerous curved diaphragms and strong acanthopores, a combination of characters which has not been found well developed in any of the Russian forms, although two new species are referred to this division. A second generic group, of which the American forms Mesotrypa discoidea Ulrich and M.? rotunda Ulrich, from the Mohawkian rocks of Minnesota, are typical, is represented by the very similar Russian form M. discoidea variety orientalis. The latter group, with its few curved diaphragms and absence of acanthopores, suggests alliance with other genera, especially Diplotrypa. A third division of the genus is known only from the specimens here described as M. millepoacea, new species, and the new variety parva, in which the absence of acanthopores and the presence of very numerous and exceptionally small mesopores are the main peculiarities.
Nickles & Bassler (1900):
- Zoarium emisperic, conical, or discoidal, generally free, with an epitheca on the under surface; zooecia prismatic or cylindrical, with oblique and sometimes funnel-shaped diaphragms, which are probably modified cystiphragms; zooecia more or less separated by angular mesopores, which become smaller with age, and are intersected by numerous diaphragms; acanthopores generally present, sometimes of large size.