Orbulinoides sp. Specimens which cannot be assigned to established species
Taxonomy
Citation: Orbulinoides Cordey, 1968, emended Proto Decima&Bolli, 1970 taxonomic rank: GenusType species: Porticulasphaerabeckmanni Saito, 1962Taxonomic discussion: Saito (1962) first noticed that the description and illustrations given by Bolli and others (1957) under Porticulasphaeramexicana were related to a species different from Cushman’s species mexicana (which was included in the genus Globigerapsis by Saito, 1962). Saito erected the new species Porticulasphaerabeckmanni for this form. In 1968 the genus Porticulasphaera, being based on a misidentified type-species, was invalidated and Cordey (1968) and Blow and Saito (1968a) erected the new genus Orbulinoides for Saito’s species beckmanni. It is worth mentioning that Cordey (1968) is now credited with the genus Orbulinoides since his paper was published a few months earlier than Blow and Saito’s (1968a) to which Cordey (1968) referred several times in his description (see Blow and Saito, 1968b). Both Blow and Saito’s and Cordey’s papers include an exhaustive description of the monospecific genus Orbulinoides. While Blow and Saito stated that “the description given by Bolli, Loeblich and Tappan (1957) under ‘Porticulasphaeramexicana’ is a specific description of the forms here referred to Orbulinoidesbeckmanni (Saito)”, Cordey (1968) described new characters differentiating the genus Orbulinoides from the other globigerinathekids. In particular, according to him, the numerous supplementary apertures in O. beckmanni are not “directly connected with the outside of the test”, but “they open into a small cavity”, called a vestibule. He also stated that O. beckmanni is unrelated to either G. kugleri or G. barri as it derives from a globorotaloid ancestor (because the aperture in the early chambers is umbilical-extraumbilical) instead of from a globigerinid ancestral form like the other two species. The genus Orbulinoides was subsequently revised and emended by Proto Decima and Bolli (1970). These authors confirmed Cordey’s (1968) observations that the numerous sutural supplementary apertures in the early stage open into vestibules, the thick wall of which has separate apertures; in addition, they also mentioned that the genus Orbulinoides may possess few areal apertures in the last two large chambers and some irregular bulla-like structures in between or covering sutural supplementary apertures in the adult stage. These bulla-like structures were not mentioned by Toumarkine (1983) or Toumarkine and Luterbacher (1985).
Distinguishing features: Parent taxon (Globigerinidae): Wall spinose, usually with 3½-6 globular chambers in final whorl, trochospiral or planispiral This taxon: Spherical test with numerous small secondary apertures
NB These concise distinguishing features statements are used in the tables of daughter-taxa to act as quick summaries of the differences between e.g. species of one genus. They are being edited as the site is developed and comments on them are especially welcome.
Description
Biogeography and Palaeobiology
Most likely ancestor:Globigerinatheka - at confidence level 0 (out of 5). Data source: .
Biostratigraphic distribution
Geological Range: Last occurrence (top): at top of E12 zone (100% up, 40Ma, in Bartonian stage). Data source: Total of ranges of the species in this database First occurrence (base): within E12 zone (39.97-40.40Ma, base in Bartonian stage). Data source: Total of ranges of species in this database
Plot of occurrence data:
Range-bar - range as quoted above, pink interval top occurs in, green interval base occurs in.
Triangles indicate an event for which a precise placement has been suggested
Neptune data: This is a higher taxon page so Neptune data is not plotted. See also: customisable plot Parent: Globigerinidae
Primary source for this page: Premoli Silva et al. 2006 - Eocene Atlas, chap. 7, p. 206
References:
Premoli Silva, I., Wade, B. S. & Pearson, P. N. (2006). Taxonomy, biostratigraphy, and phylogeny of Globigerinatheka and Orbulinoides. In, Pearson, P. N., Olsson, R. K., Hemleben, C., Huber, B. T. & Berggren, W. A. (eds) Atlas of Eocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication . 41(Chap 7): 169-212. gsO
Orbulinoides compiled by the pforams@mikrotax project teamviewed: 14-10-2024
