Spiroclypeus carpaticus ( Uhlig, 1886 )

Less, György & Özcan, Ercan, 2008, The late Eocene evolution of nummulitid foraminifer Spiroclypeus in the Western Tethys, Acta Palaeontologica Polonica 53 (2), pp. 303-316 : 312-313

Spiroclypeus carpaticus ( Uhlig, 1886)

Fig. 7R, S, U–Z, AA–AD.

1886 Heterostegina carpatica sp. nov.; Uhlig 1886: 201–202, pl. 2: 14–15; text−fig. 10.

1906 Spiroclypeus granulosus sp. nov.; Boussac 1906: 96–97, pl. 2: 15–18; pl. 3: 19.

1957 Spiroclypeus carpaticus ( Uhlig, 1886) ; Bieda 1957: 208, 224–225, pl. 12: 3, 5, 6.

1961 Spiroclypeus granulosus Boussac, 1906 ; Roveda 1961: 195–201, pl. 16: 13–16; pl. 17: 1–3; pl. 18: 7, 8; pl. 19: 12, 13.

1963 Spiroclypeus carpaticus ( Uhlig, 1886) ; Bieda 1963: 106, pl. 17: 12, 13 (?).

1964 Spiroclypeus carpaticus ( Uhlig, 1886) ; Hottinger 1964: pl. 7: 6.

1977 Spiroclypeus granulosus Boussac, 1906 ; Hottinger 1977: text−fig. 48G, H.

1986 Spiroclypeus granulosus Boussac, 1906 ; Schiavinotto 1986: pl. 1: 1–4; pl. 2: 1–5.

1999 Spiroclypeus granulosus Boussac, 1906 ; Less 1999: 356, pl. 2: 3, 4.

2005 Spiroclypeus carpaticus ( Uhlig, 1886) ; Less et al. 2005: 98, photo 101/18.

Diagnosis.—Involute, disc−shaped test with well−developed lateral chamberlets. Most of the surface is covered by granules except the peripheries where usually a rectangular septal network can be seen. The proloculus is small to medium−sized; the coiling of the spiral is moderately tight. The number of pre−heterosteginid postembryonic chambers (parameter X) is usually 1–2, rarely 3; its mean value is less than 2.7, which distinguishes it from Spiroclypeus sirottii sp. nov. The secondary chamberlets are quite regularly arranged and densely spaced and of nearly rectangular shape.

Description

External features ( Fig. 7R, S).—The test is small (1.5 to 4 mm in diameter), involute, biconvex, disc−shaped with a very slightly inflated, broad umbonal part occupying 60–90% of the test’s diameter. It is covered by granules, which are slightly larger in the centre than towards the shell’s periphery where they are absent and where a regular, rectangular network of primary and secondary septal sutures may often develop. No significant difference in adult shell size can be recognized between A− and B−forms.

Internal features.—The equatorial section of A−forms: The proloculus is small to medium−sized (P = 100–200 µm, Pmean = 115–155 µm) and (after a kidney−shaped second chamber of similar size) followed by a moderately tightly coiled spiral with 2.5 to 4 whorls (d = 450–950 µm, dmean = 600–750 µm; D = 950–1700 µm, Dmean = 1150–1550 µm; K = 40–63, Kmean = 51–60). The chambers are very high; the primary septa are very strongly curved backwards. After a very few undivided (operculinid) postembryonic chambers (X = 1–3, very rarely 4; Xmean = 1.2–2.7) all the successive chambers are subdivided into chamberlets that are quite regularly arranged and densely spaced (S = 4–9, very rarely 3; Smean = 4.3–7) and of nearly rectangular shape.

The equatorial section of B−forms ( Fig. 7 AD): The single specimen from sample Kisgyőr, Remete−kút 3, exhibits a microsphere of 15 µm in diameter. It is followed by about 14 undivided (operculinid) chambers before the appearance of the first subdivided chamber after which undivided chambers can rarely reappear. The arrangement and shape of chamberlets in the adult stage do not differ from those of the A−forms.

Axial section ( Fig. 7W, Y): Relying also on Boussac’s (1906: pl. 3: 19) and Roveda’s (1961: pl. 17: 1–3; pl. 19: 12, 13) figures and descriptions, the test is slightly inflated, involute and biconvex. Lateral chamberlets are well developed, piles are well visible.

Remarks.— Uhlig (1886: text−fig. 10) provided two good figures of the equatorial section of A−forms when introducing the name “ carpatica ” for specimens from Woła Łużańska ( Poland). In both sections the number of post−embryonic undivided chambers (parameter X) is 2 and in the upper figure the number of chamberlets in chamber 14 (parameter S) is 7. These parameters correspond well to our material, therefore the name Spiroclypeus carpaticus can be applied to them. Based on Roveda’s (1961), Schiavinotto’s (1986) and our data and the figures of Boussac’s (1906) S. granulosus from Priabona we conclude that Uhlig’s (1886) S. carpatica is synonymous but has priority making S. granulosus invalid. Moreover, the name “ granulosus ” was confusingly used previously for Heterostegina gracilis (see Less et al. 2008).

The figures of Boussac (1906), Roveda (1961), Hottinger (1977) and Schiavinotto (1986) cited in the synonymy illustrate specimens from the very close vicinity of our sample from Priabona , while Hottinger’s (1964) form from Benidorm and Less’ (1999) specimens from Kisgyőr come from the same samples which we have studied.

The distinction between S. sirottii and S. carpaticus is discussed under the description of the former. According to the figures of Western Tethyan upper Oligocene and lowermost Miocene Spiroclypeus by Henson (1937), Cahuzac and Poignant (1997), and also based on our unpublished data, it seems that they differ from S. carpaticus in having a much looser spire, and a larger proloculus (compare them also in Figs. 7 and 8 ). Since no Spiroclypeus have been found in the Western Tethyan lower Oligocene and also because the above differences between S. carpaticus and the upper Oligocene and lowermost Miocene forms do not allow to directly link them phylogenetically, we suppose that S. carpaticus became extinct with no successors at the very end of the Priabonian.

Geographic and stratigraphic distribution.—Late Priabonian (SBZ 20) of the Polish (Wola Łużańska, Bukowiec) and Slovakian (Raslavice) Carpathians, of N Italy ( Priabona , blue claystone; Possagno, Calcare di Santa Giustina, samples Possagno 1 and 2), NE Hungary (Kisgyőr, sample Remete−kút 3), SE Spain (Benidorm).

Figures

Fig. 8. Equatorial sections of megalospheric upper Oligocene and lowermost Miocene Spiroclypeus blanckenhorni Henson, 1937 from Turkey. A. Upper Chattian, SBZ 23, Kelereşdere (E Turkey), sample KEL 29, MÁFI O. 08.3. B. Lower Aquitanian, SBZ 24, Tuzlagözü (Central Turkey), sample TUZ 1, ITU O/TUZ.1−42.