Catalog - Prosphaeroidinella

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Prosphaeroidinella

Citation: Prosphaeroidinella Ujiie 1976

Type species: Sphaeroidinella disjuncta Finlay

In the type species, Sphaeroidinella disjuncta Finlay, honey-comb wall structure becomes considerably obscure at the earlier portion of specimen because of remarkable piling-up of lamellae during the course of growth. Since this type of wall-thickening is accomplished by the outward growth of respective calcite crystals disposed radially against test-surface, the present secondary process does not produce directly such a smooth test-surface as seen in Sphaeroidinella or Sphaeroidinellopsis but still maintains the rough surface. Moreover, S. disjuncta is provided with somewhat more broadly opened aperture than in Sphaeroidinellopsis.

Another species also belonging to Prosphaeroidinella, P. parkerae Ujiie, shows much more widely spaced framework of honey-comb structure. The frame is distinctly larger than that of normal species of Globigerinoides and solely comparable sized frame can be recognized at the outer face of an inner layer (designated as Layer 2 in tf. I) of wall in Sphaeroidinellopsis or Sphaeroidinella. The outer layer (Layer 3) is so-called cortex layer, whose outer surface is quite smooth paved by the calcite basal planes. The smoothness corresponds to that at the inner surface of wall. These facts imply some essential difference in genesis between the two types of layer. As will be discussed and inferred in Remarks on the species, the inner layer may be a fundamental constituent of wall in Sphaeroidinellopsis or Sphaeroidinella, while the outer cortex layer may be secondary but advanced component characteristic to the genera. Therefore, I suppose that the wall structure peculiar to P. parkerae Ujiie may not have been resulted from such a peeling-out of outer Layer 2 of Sphaeroidinellopsis or Sphaeroidinella through certain chemical dissolution or physical process (e. g., some vibration effect during the maceration of sediment samples) as Parker (1967) thought previously, but it may represent a kind of atavism. In this respect, the species must belong to the genus Prosphaeroidinella, although there is necessity to consider the phylogenetic difference between P. parkerae Ujiie and P. disjuncta (Finlay).

The present supposition from taxonomic views of the two species seems to be substantiated by their stratigraphic occurrences. Last appearance of P. disjuncta is followed immediately by the initial appearance of rather primitive but real Sphaeroidinellopsis species at the boundary between the N. 12 and N. 13 of Blow's (1969) zones, whereas P. parkerae Ujiie occurs concurrently with well-developed Sphaeroidinellopsis and with Pliocene species of Sphaeroidinella.

The following species were included in Prosphaeroidinella by Ujiie in 1976:

Prosphaeroidinella disjuncta (Finlay) = Sphaeroidinella disjuncta Finlay, 1940;
Prosphaeroidinella parkerae Ujiie, 1976.

Two other species have appeared in taxonomic lists (e.g Fordham 1986), but these appear to be nomina nuda and they are not mentioned in the descriton of Prosphaeroidinella by Ujiie 1976. [my interpretation - JRY 2019, aided by correspondence with Francois le Coze]

Prosphaeroidinella challengerae Ujiie 1975 - this is listed in Ujiie 1975 but with a note that it is to be described in a separate paper in press (ie. Ujiie 1976), possibly he subsequently realised that this species was the same as S. disjuncta.
Prosphaeroidinella philippinensis Ujiie 1976 - we do not know where this name was published.

References:

Fordham, B. G. (1986). Miocene-Pleistocene planktic foraminifers from D.S.D.P. Sites 208 and 77, and phylogeny and classification of Cenozoic species. Queensland, Australia. (6): 1-224. gs

Ujiie, H. (1975). An early Miocene planktonic foraminiferal fauna from the Megami Formation, Shizuoka Prefecture. Bulletin of the national Science Museum, Tokyo. 1: 83-92. gs

Ujiie, H. (1976). Prosphaeroidinella, n. gen.: Probable ancestral taxon of Sphaeroidinellopsis (Foraminifera). Bulletin of the national Science Museum, Tokyo. 2(1): 9-26. gs

CATALOG OF ORIGINAL DESCRIPTIONS: Prosphaeroidinella Ujiie 1976

Prosphaeroidinella

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			Prosphaeroidinella parkerae Ujiie 1976
			Prosphaeroidinella valleriae Brönnimann, Whittaker & Parisi 1988