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Species Globigerinatheka subconglobata Shutskaya 1958 | ||||||
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Diagnosis / Definition: | ||||||
Pearson et al. (2006): DESCRIPTION. Type of wall: Spinose, cancellate, rather thick, with pores about 0.04 mm in diameter, frequently recrystallized. Test morphology: Test globular to nearly spherical, formed by 3 whorls, initially coiled in low trochospire becoming progressively higher and slightly streptospiral in the last whorl; chambers globular, small and very slowly increasing in size as added up to half of the second whorl, then increasing gradually but progressively faster; the first chamber of the last whorl is about half the size of the antepenultimate, the latter and penultimate chamber have a very similar size, the last chamber is typically smaller and flattened; initially 4-5 chambers per whorl, and typically 4 chambers in the last whorl; in spiral view chambers of the last whorl longer than wide, elongate in coiling direction, in umbilical view the last chamber is small and straddles the three previous chambers; sutures distinct throughout, weakly depressed in the inner coils, then moderately depressed; primary aperture umbilical, a low rather wide arch at the base of the last chamber, one to two small low arched secondary apertures at the intersections between the base of the last chamber and previous sutures, apertures frequently poorly visible. Size: The size of specimens is highly variable ranging in diameter from 0.30 to 0.65 mm; medium-sized specimens are rather common. Diameter of the lectotype (Shutskaya, 1958, pl. 1, fig. 8) ca. 0.50 mm. |
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Discussion / Comments: | ||||||
Pearson et al. (2006): DISTINGUISHING FEATURES.- Globigerinatheka subconglobata is characterized by its evolute outline, four chambers in the last whorl, crown-like flatter final chamber, small apertures and initial spire which is central in position. Globigerinatheka subconglobata shows some variability in the size and shape of the primary and secondary apertures, whereas the general size of the test is highly variable (see above). In smaller morphotypes, secondary apertures are small or even poorly visible. The wall of G. subconglobata is frequently recrystallized. DISCUSSION.- Shutskaya (1958) first described and illustrated this taxon as Globigerinoides subconglobatus even though she indicated Khalilov as its author in referring to a manuscript never published; because of Khalilov's manuscript, Shutskaya did not indicate the holotype; Bolli (1972) selected as a lectotype the specimen that Shutskaya (1958) illustrated in her pl. 1, fig. 8. Globigerinatheka subconglobata (including the smallest specimens) is the only globigerinathekid possessing four visible chambers in the last whorl. Because the original figures of G. subconglobata lack spiral and side views, most authors illustrated this species only in umbilical view, until this atlas. Judging from the figures, the specimen illqtrated by Bolli (1957) as G. index (pl. 36, figs. 14a-b) appears to be one of the best representatives of G. subconglobata. Bolli (1 972) considered G. curvyi as a subspecies of G. subconglobata; however, in our opinion these species have little in common. Globigerinatheka subconglobata is characterized by a longer and much higher spire, more numerous chambers (four in the last whorl), a small flattened final chamber not enveloping or covering previous ones. Blow (1979, p. 819) suggested that G. subconglobata was a junior synonym of G. kugleri, a synonymy here rejected on the basis of the very different outline and coiling mode (see above). The specimen illustrated by Toumarkine (1983) as Globigerinatheka subconglobata subconglobata (pl. 2 1, fig. 16) possesses a subtriangular outline similar to G. kugleri. PHYLOGENETIC RELATIONSHIPS.- Globigerinatheka subconglobata is the earliest globigerinathekid and evolved in the early middle Eocene Zone E8, probably from Guembelitrioides nuttalli. It is considered ancestral to all the other globigerinathekid lineages or groups. GEOGRAPHIC DISTRIBUTION.- Cosmopolitan, common. STABLE ISOTOPE PALEOBIOL0GY.- Recorded as a surface mixed-layer dweller by Pearson and others (1 993) |
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Systematics: | ||||||
32 Familia Globigerinidae Genus Globigerinatheka Species Globigerinatheka subconglobata 35 Ordo Foraminiferida Superfamilia Globigerinaceae Familia Globigerinidae Genus Globigerinatheka Species Globigerinatheka subconglobata |
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Synonym list: | ||||||
Van Eijden & Smit (1991): 1958 Globigerinoides subconglobatus var. subconglobatus Shutskaya. - Shutskaya : 86-87 pl. 1, figs. 4-11
1991 Globigerinatheka subconglobata Shutskaya. - Van Eijden & Smit : p.111
Pearson et al. (2006): 1957 Globigerapsis index Finlay. - Bolli : p.165 pl. 36; fig. 14a-b [middle Eocene Globigerapsis kugleri Zone, Navet
Fm., Trinidad]; [Not Finlay, 1939]
1958 Globigerinoides subconglobatus var. subconglobatus Shutskaya. - Shutskaya : p.86 pl. 1; fig. 4-11 (no
designated holotype; lectotype designatcd by Blow,
1979:819, as the specimen in fig. 8) [upper Eocene,
Kerestinskiy horizon, figs. 4, 6-8, l l , Belaya River,
Nal'chik region; figs. 5, 9, 10, Nagutskaya well,
Mineralovodsk region, Caucasus]
1971 Globigerapsis subconglobatus Shutskaya. - Toumarkine : pl. 3; fig. 13-14 [middle Eocene Globorotalia
lehneri/Hantkenina dumblei Zone, Halimba borehole,
Bakony, Hungary]
1972 Globigerinatheka index index Finlay. - Bolli : pl. 1; fig. 6-7 [middle Eocene Globigerinatheka subconglobata
subconglobata Zone, Possagno Section, Italy]; [Not
Finlay, 1939]
1972 Globigerinatheka subconglobata subconglobata Shutskaya. - Bolli : p.134 text-fig. 43-46 (text-fig. 44 lectotype = pl. 1, fig. 8 of Shutskaya, 1958);
pl. l, fig. 8-10, fig. 15- 16 [middle Eocene Globigerinatheka
subconglobata subconglobata Zone, Possagno Section,
northern Italy]
? 1974 Globigerinatheka subconglobata subconglobata Shutskaya. - Fleisher : pl. 8; fig. 9 [middle Eocene
Zone P1 l, DSDP Site 220, Arabian Sea]
1975 Globigerinatheka index Finlay. - Stainforth et al. : fig. 56.5, 7, 9 (from Bolli, 1972: pl. l : figs. 2,6,7);
[Not Finlay, 1939]
1975 Globigerinatheka subconglobata subconglobata Shutskaya. - Toumarkine : pl. 4; fig. 1 [middle
Eocene Globorotalia lehneri Zone, DSDP Site 3 13, Mid Pacific Mountains]
1975 Globigerinatheka subconglobata Shutskaya. - Stainforth et al. : fig. 90.1-5 (from Bolli, 1972);
fig. 90.6-11 (from Shutskaya, 1958)
non 1975 Globigerinatheka subconglobata subconglobata Shutskaya. - Toumarkine : pl. 4; fig. 2 [middle
Eocene Globorotalia lehneri Zone, DSDP Site 3 13, Mid
Pacific Mountains]; (= G. korotkovi)
1978 Globigerinatheka subconglobata subconglobata Shutskaya. - Toumarkine : pl. 3, fig. 1, 3 [middle Eocene Globorotalia lehneri to Truncorotaloides rohri Zone, DSDP Site 360, South Atlantic Occan];
fig. 2 [middle Eocene Hantkenina aragonensis to Globorotalia lehneri Zone, DSDP Site 363, South Atlantic Ocean]
1978 Globigerinatheka mexicana mexicana Cushman. - Toumarkine : pl. 4; fig. 5 [middle Eocene Hantkenina
aragonensis to Globorotalia lehneri Zone, DSDP Site 363,
South Atlantic Ocean]
p 1983 Globigerinatheka subconglobata subconglobata Shutskaya. - Toumarkine : pl. 21, fig. 17-20 [middle Eocene Globigerinatheka subconglobata subconglobata Zone, Possagno Section, northern Italy];
figs. 18-20 [middle Eocene, Possagno Section, Italy] (not fig. 16
[middle Eocene, Beni Mazar, Boukhary Section, Nile
Valley, Egypt] = G. kugleri)
1983 Globigerinatheka subconglobata Shutskaya. - Pujol : pl. 5; fig. 8-9 [middle Eocene Zones P1 1-13, DSDP Hole 516F, Rio
Grande Rise, South Atlantic Ocean]
1983 Globigerinatheka mexicana mexicana Cushman. - Toumarkine : pl. 20; ?fig. 36-38 [middle Eocene Zones P12-14, DSDP Site 305,
Shatsky Rise, northwest Pacific Ocean]; [Not Cushman,
1925]
? 1985 Globigerinatheka subconglobata Shutskaya. - Snyder & Waters : pl. 5; fig. 5-6 [fig. 5, DSDP Site 549; fig.
6, DSDP Hole 548A, Goban Spur, eastern North Atlantic
Ocean]
1993 Globigerinatheka subconglobata Shutskaya. - Pearson et al. : pl. 2; fig. 16-17 [middle Eocene, DSDP Site 523,
South Atlantic Ocean]
1995 Globigerinatheka subconglobata Shutskaya. - Poag & Commeau : pl. 4; fig. 18-19 [middle Eocene Zone P1 l, Hammond core,
1,320-1,330 ft, SW Salisbury Embayment, Virginia-
Maryland]
2006 Globigerinatheka subconglobata Shutskaya. - Pearson et al. : p.200 pl. 7.10; fig.1-20 (Pl. 7.10, Fig. l : reillustration of lectotype of
Globigerinoides subconglobatus Shutskaya var.
subconglobatus Shutskaya)
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References: | ||||||
Bolli,H.M. (1957): Shutskaya,E.K. (1958): Toumarkine,M. (1971): Bolli,H.M. (1972): Fleisher,R.L. (1974): Toumarkine,M. (1975): Stainforth,R.M.; Lamb,J.L.; Luterbacher,H.P.; Beard,J.H. and Jeffords,R.M. (1975): Toumarkine,M. (1978): Toumarkine,M. (1983): Toumarkine,M. (1983): Pujol,C. (1983): Snyder,S.W. and Waters,V.J. (1985): Van Eijden,A.J.M. and Smit,J. (1991): Pearson,P.N.; Shackleton,N.J. and Hall,M.A. (1993): Poag,C.W.. and Commeau,J.A.. (1995): Pearson,P.N.; Olsson,R.K.; Hemleben,C.; Huber,B.T. and Berggren,W.A. (2006): |
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Anonymous: Unedited TaxonConcept data | ||||||
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