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Species Praemurica lozanoi Colom 1954 | ||||||
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| Diagnosis / Definition: | ||||||
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Pearson et al. (2006): DESCRIPTION. Type of wall: Smooth, cancellate, nonspinose. Test morphology: Test trochospiral, asymmetrically biconvex; the first two whorls coiled in medium high, tight spire then the coiling mode tends to become more evolute and the more evolute spire increases markedly in height; chambers globular, increasing gradually in size as added, 5-6 (more typically 6) in the last whorl; the last chamber in some instances more oval on the umbilical side; equatorial periphery subcircular, moderately lobate; sutures depressed, mainly straight and radial on both sides; umbilicus mediumsized and deep; aperture a distinct, moderately high arch, interiomarginal, umbilical; in specimens characterized by more oval last chamber the aperture tends to extend extraumbilically. Size: 0.35-0.40 mm and a height of 0.45 mm (Colom, 1954). |
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| Discussion / Comments: | ||||||
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Pearson et al. (2006): PROBLEMATICA.- Praemurica? lozanoi (Colom) is an enigmatic taxon. It appears in the lower part of the lower Eocene with seemingly no ancestral linkage. It is a nonspinose form and has a wall texture similar to Praemurica (dutertrei-type cancellate) although we have not found any Paleocene species that might be an ancestor to range into the Eocene. Hence, our assignment to the genus is tentative until further studies can establish its phylogeny. DISTINGUISHING FEATURES.- This species is characterized by its medium high, relaxed (evolute) trochospire late in ontogeny, five to six globular chambers in the outer whorl, subcircular equatorial periphery and (predominantly, but not exclusively) intraumbilical aperture. DISCUSSION.- Colom (1954) produced a plate with 48 outline drawings of his species lozanoi but did not identify one of these as a holotype. They include a rather wide range of morphologies, from relatively low-spired forms usually with 4-4 1/2 chambers in the final whorl, interpreted as juveniles, to more high-spired forms with five to six chambers. Blow (1 979) selected one of these, a specimen with 6 chambers, as a lectotype (Colom, 1954, pl. 2, fig. 45). Colom (1954) described Globigerina aspensis (= Acarinina aspensis) from the same locality as lozanoi. Both species are loosely coiled with a large, open umbilicus and have a similar number of chambers in the final whorl but lozanoi is smaller in size and high spired, whereas aspensis is larger and very low spired. The wall of aspensis was described as having pustules and the wall of lozanoi was described as smooth. Since Colom did not designate any type specimen(s) and his material is said to be in his personal collections and may, in fact, be lost, it is difficult to assess the two species from Colom's illustrations alone. However, we have been able to examine well preserved material from various localities of both taxa and although the two morphotypes were described from the same locality and have similar short stratigraphic ranges they appear to be unrelated as can be seen from comparison of surface wall texture, chamber shape and apertural disposition. Bolli (1 957b) described Globigerina prolata from the Morozovella formosa formosa Zone (= E5). Hillebrandt (1976) was of the opinion that G. prolata was ancestral to G. nuttalli, whereas Blow (1979) regarded G. prolata as a subspecies of G. lozanoi. Blow (1979) figured a series of specimens (his pl. 145, figs. 1-5) to illustrate the complete gradation of the prolata morphotype into the lozanoi morphotype. However, the holotype of prolata is very poorly preserved and appears to be mostly an internal mould. Globigerina prolata has not been identified by many workers and, in fact, Tourmarkine and Luterbacher (1985) did not include it in their treatment of Paleocene and Eocene planktonic foraminifera. This would seem to indicate uncertainty over the validity of this morphotype. We think it is prudent not to use this morphotype until its taxonomic status is clarified. PHYLOGENETIC RELATIONSHIPS.- Although Hillebrandt (1976) and Blow (1979) regarded prolata as phylogenetically or ontogenetically linked to lozanoi. Blow stated (1979, p. 855) that the origin of G. lozanoi (sensu lato) was unknown, but that inasmuch as prolata morphotypes appear earlier in the succession that the ancestor of the lozanoi group was essentially a "four-chambered last-whorl turborotaliid morphotype." Assignment to Turborotalia (as delineated here) is clearly not possible owing to the different wall texture and apertural disposition. At the same time we believe it is unrelated to A. aspensis and A. pentacamerata for similar reasons. The wall texture (dutertrei-type cancellate) and apertural disposition of lozanoi are reminiscent of the Paleocene (essentially early Paleocene) genus Praemurica (see treatment of that genus in Olsson and others, 1999), although the relatively high spire in some individuals is not characteristic of the genus. At the same time we are unable to propose a suitable praemuricate ancestor for the lozanoi-prolata group in the early Eocene. Owing to the uncertainty surrounding the affinities and ancestry of lozanoi we assign it here provisionally to Praemurica (the obvious uncharacteristic high spire and the distinct stratigraphic gap from Zone P3 to E5/6 notwithstanding) and provide a separate entry for it here. Praemurica? lozanoi did not give rise to Guembelitroitdes nuttalli as suggested by Blow (1979, p. 855). STRATIGRAPHIC RANGE.- P. lozanoi ss.: Zone E6 - E1O; P. lozanoi s.l. (including prolata morphotype): E5-E9 (upper part). GEOGRAPHIC DISTRIBUTION.- Cosmopolitan, more common in mid- to low latitudes. STABLE ISOTOPE PALEOBIOL0GY.- No data available. REPOSITORY.- Deposited in Colom's personal collection (fide Ellis and Messina). |
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| Systematics: | ||||||
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35 Ordo Foraminiferida Superfamilia Globigerinaceae Familia Truncorotaloididae Genus Praemurica Species Praemurica lozanoi |
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| Synonym list: | ||||||
| Pearson et al. (2006): 1954 Globigerina lozanoi Colom. - Colom : p.149 pl. 2; fig. 1-48, fig. 45 lectotype (designated by Blow, 1979:854) [lower -
middle Eocene (upper Ypresian - lower Lutetian) Alicante,
Spain]
? 1957 Globigerina prolata Bolli. - Bolli : p.72 pl. 15; fig. 24-26 [lower Eocene, Globorotalia formosa formosa and
Globorotalia aragonensis Zones, Lizard Springs Fm.,
Trinidad]
1961 Globigerina lozanoi Colom. - Bermudez : p.1188 pl. 4; fig. 7 [lower
Eocene, Zone P9, Universidad Fm., Havana, Cuba]
1976 Globigerina (Eoglobigerina) lozanoi Colom. - Hillebrandt : p.336 pl. 3; fig. 8-11, ?12, 13-16, ?17 [lower Eocene
Globorotalia (Planorotalites) palmerae Zone, Agost
section, SE Spain]
1979 Globigerina lozanoi prolata Bolli. - Blow : p. 856-858 pl. 145, fig. 1 [Zone P9, Langley Fm., ER.449, Jamaica];
pl. 250, fig. 10 [topotype, Globorotalia formosa formosa
Zone, Lizard Springs Fm., Trinidad]
1979 Globigerina lozanoi lozanoi Colom. - Blow : p. 854-855 pl. 145, fig. 2-9 [lower Eocene Zone P9, Langley
Formation, Jamaica];
pl. 250, fig. 1 [lower Eocene Zone
P9, Universidad Fm., Cuba]
1983 Globigerina lozanoi Colom. - Toumarkine : p. 115-116 pl. 9, fig. 6-11 (fig. 6-8 from
Colom, 1954, pl. 2, fig. 31, 36, 45; 45 = lectotype);
fig. 9-11 [A. pentacamerata Zone, lower Eocene, Richmond
Fm., Jamaica]
1985 Globigerina lozanoi Colom. - Toumarkine & Luterbacher : p.127 fig. 28.9-11 [A. pentacamerata Zone, lower Eocene,
Richmond Fm., Jamaica]
non 1990 Globigerina lozanoi Colom. - Stott & Kennett : p.559 pl. 7; fig. 6-7
1991 Subbotina lozanoi Colom. - Nocchi et al. : pl. 2; fig. 13-15 [lower Eocene Zone P9, DSDP Hole 702B,
subantarctic South Atlantic Ocean]
non 1991 Subbotina lozanoi Colom. - Nocchi et al. : pl. 2; fig. 16 [= Subbotina hagni?]
2001 Globigerina prolata Bolli. - Warraich & Ogasawara : p.46 fig. 13, 16, 20, 21 [Zone E5, Dungan Fm.,
Sulaiman Range, Pakistan]
2001 Globigerina lozanoi Colom. - Warraich & Ogasawara : p.45 fig. 14.1-3 [Zone E5, Dungan Fm., Sulaiman
Range, Pakistan]
2006 Praemurica? lozanoi Colom. - Pearson et al. : p.391 pl. 12.6; fig. 1-16 (Pl. 12.6, Fig. l : reillustration of lectotype of
Globigerina lozanoi Colom)
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| References: | ||||||
Colom,G. (1954): Bolli,H.M. (1957): Bermudez,P.J. (1961): Hillebrandt,A. (1976): Blow,W.H. (1979): Toumarkine,M. (1983): Toumarkine,M. and Luterbacher,H.P. (1985): Stott,L.D. and Kennett,J.P. (1990): Nocchi,M.; Amici,E. and Premoli Silva,I. (1991): Warraich,M.Y.. and Ogasawara,K.. (2001): 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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