Catalog - Rectuvigerina

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Rectuvigerina

Citation: Rectuvigerina Mathews, 1945

Type species: Rectuvigerina (Rectuvigerina) multicostata (Cushman and Jarvis) = Siphogenerina multicostata Cushman and Jarvis, 1929

Described on page(s) : 590, 598, 601

[Mathews 1945]: The group of species with a triserial neanic stage developing from Uvigerina and formerly placed in “Siphogenerina” is now anonymous. For this group a new genus is erected. [See also “Siphogenerina” Schlumberger, emend. Mathews, 1945.]

Test free, elongate, round in cross section; initial chambers triserial, later uniserial with or without intermediate biserial stage; longitudinal costae either continuous or interrupted by sutures; wall calcareous, perforate; internal tube connecting later chambers, terminating in round aperture with phialine lip.

This genus was apparently derived from Uvigerina by the addition of one or more uniserial chambers and the development of an internal tube. Phylogeny of individual species indicates a multiple origin through various species of Uvigerina. Family Uvigerinidae, Subfamily Uvigerininae.

[Mathews 1945 sensu stricto Mathews 1945]: Test like Uvigerina with uniserial chambers added; sutures straight in uniserial portion; costae very weak to strong, numerous, continuous or discontinuous over sutures, often anastomosing into basal spines.

[Mathews 1945]: [p. 598]: Division into subgenera – the wide range in ornamentation and test form among species of Rectuvigerina justifies a subdivision of the genus. This is further encouraged by the manner in which the genus may be divided into two natural subgeneric groups. One of the subgenera (Transversigerina) has a limited geologic range, which will enable field geologists to employ it in stratigraphic correlations where immediate specific identification would be impossible. [See also Rectuvigerina s.s. and Transversigerina Mathews, 1945.]

[p. 601]: Relationships of Rectuvigerina – Morphologic similarity and close phylogenetic relationship of certain genera to Siphogenerina, as formerly conceived, caused various writers to shift species from one genus to another. These so-called “related” groups include at least eight genera distributed in two families. Such confusion suggests that the genus concerned includes unrelated forms. Separation of Rectuvigerina from other groups, however, requires a short discussion of only three genera, two because of common phylogeny and a third because of isomorphism.

Sagrina (type, S. pulchella d’Orbigny, 1839), which has contained at some time many of the species now assigned to Rectuvigerina, need not be considered here. The genotype shows a close affinity to Bolivina (type, B. plicata d’Orbigny, 1839) and may, indeed, be considered a part of that genus (Cushman, 1926, U.S. Nat. Museum, Proc., vol. 67, p. 2).

The distinction between Rectuvigerina and Uvigerina is difficult since the former was derived from the latter. Differences between these genera may be listed in two comparisons: (1) Rectuvigerina has one or more uniserial chambers; Uvigerina is triserial throughout. (2) Rectuvigerina has an internal siphon; Uvigerina has not. Where such simple changes of structure represent the only observable differences between groups, they may be repeated independently at different geologic intervals. Thus, species of Rectuvigerina have arisen from different species of Uvigerina during different geologic ages. Since Uvigerina is confused with Rectuvigerina especially when specimens of Rectuvigerina are in their youthful stage before the addition of uniserial chambers, a specimen in this stage must be placed generically by sectioning to determine the presence of an internal tube.

There are some species now assigned to Uvigerina which show characteristics of both Uvigerina and Rectuvigerina. Until further evidence indicates definitely in which genus these forms should be placed, it is thought advisable to leave them where originally assigned. Some of these forms are listed below:

U. bifurcata d’Orbigny, 1939
U. boniensis Fornasini, 1888, of Macfadyen, 1930
U. peregrina var. bradyana Cushman, 1923
U. longa var. denticosta Cushman and Bermudez, 1937
U. israelskyi Garrett, 1939
U. longa Cushman and Bermudez, 1937
U. peregrina Cushman, 1923
U. schwageri Brady, 1884
U. seriata Cushman and Jarvis, 1929
U. spinicostata Cushman and Jarvis, 1929
U. tenuistriata Reuss, 1870.

A discussion of the genus Uvigerinella Cushman, 1926, is necessary because species of Rectuvigerina seem to have been derived from this genus as well as from Uvigerina. Uvigerinella sparsicostata Cushman and Laiming, 1931, appears to be the direct ancestor of Rectuvigerina smithi (Kleinpell). H.H. Renz (personal communication, Oct. 16, 1944) has found that it is very difficult to distinguish between these species in the Agua Salada group, Trinidad. (In a later communication (Dec. 16, 1944) H.H. Renz reported the presence of a siphon in U. sparsicostata. If this structure is considered more important than apertural form, this species would be better placed in Rectuvigerina.) It seems reasonable that other species of Rectuvigerina with apertural peculiarities, such as R. mayi (Cushman and Parker), might also have had a Uvigerinella ancestor. Kleinpell, however, cautions (1938, Miocene stratigraphy of California, p. 287):

“The apertural characters distinctive of this subgenus [Uvigerinella] appear to be somewhat variable, even in well preserved material, much of which seems indistinguishable from Uvigerina, sensu stricto. Most of the material available for comparative study, however, particularly the subsurface material, is not in the best state of preservation. The apertural lip is often completely broken away, and much of the neck also, rendering definite recognition of the subgenus, as such, extremely hazardous.”

The Cretaceous genus Siphogenerinoides Cushman, 1927, contains many forms closely resembling species of the post-Cretaceous Rectuvigerina. Some forms have an internal tube connecting the chambers (Siphogenerinoides clarki Cushman and Campbell, 1936) as in Rectuvigerina; others, including the genotype, S. plummeri (Cushman), are apparently without this structure. This important difference in anatomy incorporated within the same genus suggests a poorly defined group. It seems probable that some species brought together in the genus are, in reality, not closely related. Species assigned to Siphogenerinoides may have a triserial neanic stage, a biserial one, or in the megalospheric form, may be uniserial throughout. Also, members of this group may have phialine lips or arched sutures as do some species of Rectuvigerina.

Distinguishing features between the genera may be summarized in the following manner: (1) Siphogenerinoides may have a serrate aperture; Rectuvigerina never does. (2) Siphogenerinoides usually has a biserial neanic stage; Rectuvigerina always a triserial one. (3) Siphogenerinoides usually has no internal siphon; Rectuvigerina always does.

[Mathews 1945 sensu stricto Mathews 1945]: Species:

Rectuvigerina (Rectuvigerina) basispinata (Cushman and Jarvis, 1929)
R. (R.) costostriata (Galloway and Heminway, 1941)
R. (R.) fredsmithi (Garrett, 1939)
R. (R.) hubbardi (Galloway and Heminway, 1941)
R. (R.) hughesi (Cushman, 1925)
R. (R.) irregularis (Bagg, 1908)
R. (R.) mayi (Cushman and Parker, 1931)
R. (R.) multicostata (Cushman and Jarvis, 1929)
R. (R.) nicoli Mathews, 1945
R. (R.) nodifera (Cushman and Kleinpell, 1934)
R. (R.) ongleyi (Finlay, 1939)
R. (R.) optima (Cushman, 1943)
R. (R.) panggoeensis (LeRoy, 1939)
R. (R.) pohana (Finlay, 1939)
R. (R.) postprandia (Finlay, 1939)
R. (R.) prisca (Finlay, 1939)
R. (R.) pseudococoaensis (Cushman and Kleinpell, 1934)
R. (R.) rerensis (Finlay, 1939)
R. (R.) smithi (Kleinpell, 1938)
R. (R.) striata (Schwager, 1866)
R. (R.) striatissima (Stache, 1865)
R. (R.) vesca (Finlay, 1939).

[All species listed above were originally described as species of Siphogenerina, or have been classified in that genus at some time.]

References:

Mathews, R. D. (1945). Rectuvigerina, a new genus of foraminifera from a restudy of Siphogenerina. Journal of Paleontology. 19(6): 588-606. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Rectuvigerina Mathews, 1945

Rectuvigerina

References:

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