Catalog - Chiloguembelina adriatica

CATALOG OF ORIGINAL DESCRIPTIONS: Chiloguembelina adriatica Premec Fucek, Hernitz Kucenjak & Huber 2018

This page provides data from the catalog of type descriptions. The catalog is sorted alphabetically. Use the current identification link to go back to the main database.

Higher levels: pf_cat -> C -> Chiloguembelina -> Chiloguembelina adriatica
Other pages this level: C. adriatica, C. andreae, C. circumlabiata, C. fusiformis, C. midwayensis strombiformis, C. midwayensis subcylindrica, C. minutissima, C. noguerensis, C. orientalis, C. parallela, C. praecursor, C. subtriangularis, C. subwilcoxensis, C. taurica, C. ujliaensis, C. victoriana, C. vineetae, C. waiparaensis, C. woodi

Chiloguembelina adriatica

Citation: Chiloguembelina adriatica Premec Fucek, Hernitz Kucenjak & Huber 2018
Rank: Species
Type specimens: Plate 17.2, Figures 1-24; Holotype (USNM 560294) and paratypes (USNM 593428, USNM 593429, USNM 593430)
Type sample (& lithostrat): sample 1 m, 0.15 cm; Istra More-3 borehole; cored interval 1189.5-1195.5 m
Type age (chronostrat): Easy Oligocene; Zone O2
Type locality: Istra More-3 borehole (45°10’ N; 13°4’ E), North Adriatic Sea,
Type repository: USNM

Current identification/main database link: Chiloguembelina adriatica Premec Fucek, Hernitz Kucenjak, and Huber, in Premec Fucek et al. 2018

Original Description

Type of wall: Microperforate, bilamellar, the wall is 4-5 μm thick, the inner layer is usually very thin (0.4-0.5 μm), the outer layer has a submicron granular (blocky) texture (Pl. 17.1, Fig. 21), ototara-type wall (see Chapter 15, this volume); surface ornamentation consists of fine but distinct, discontinuous costae on the youngest chambers, becoming faint on last chambers, with costae aligned with the long axis of the test; the wall is evenly perforated by pores that are usually about 0.50-0.75 μm in diameter, but can exceed 1 μm as a result of dissolution, pore channels are straight.

Test morphology: Test biserial, elongate, subtriangular in outline, periphery rounded; chambers increasing moderately to rapidly in size, usually 11-12, up to 14 in adult specimens; sutures depressed, perpendicular to slightly oblique to the growth axis; aperture a low, moderately narrow to broad, symmetrical arch centered or slightly off-center from the base of the final chamber, bordered on one side by a narrow collar that thickens away from its attachment point on the chamber face. Apical angle is larger than in C. cubensis, generally about 55-60°.


Size of measured populations: Mid-latitude (Adriatic Sea): Length 0.10-0.19 mm; width 0.07-0.13 mm; breadth 0.06-0.07 mm. Low latitude (Syria): Length 0.14-0.22 mm; width 0.09-014 mm; breadth 0.07-0.08 mm.

Named after the Adriatic Sea where it occurs in the lower Oligocene

Extra details from original publication

DISTINGUISHING FEATURES.— Distinguished from Chiloguembelina cubensis by having a more rapidly flaring test outline, greater apical angle of about 55-60°, a more rapid increase in chamber size and generally a shorter and wider test. It differs from Chiloguembelina ototara and C. andreae n. sp. by the presence of fine, mostly discontinuous costae that are aligned parallel to the elongate axis of the test.

DISCUSSION.— The exceptionally well-preserved material from the Adriatic Sea and Syria enabled detailed study of the abundant biserial planktonic foraminifera. Two morphologically significant groups with costate surface ornamentation that clearly differ in shape have been observed. The first of these is the commonly identified species C. cubensis. The other group differs from C. cubensis by the growth rate of chambers, total number of chambers, apical angle and length and width of the test. The specimens with a more rapidly flaring test outline are placed in Chiloguembelina adriatica. This species appears in the uppermost Eocene Zone E16 and disappears at the end of Zone O4, with sporadic occurrences in Zone O5. In contrast, Chiloguembelina cubensis has a longer stratigraphic range with its lowest occurrence (LO) in the middle Eocene and highest common occurrence (HCO) at the top of Zone O4, above which it becomes rare and sporadic up to the uppermost Oligocene.

PHYLOGENETIC RELATIONSHIPS.— Probably evolved from C. cubensis during the latest Eocene.

STRATIGRAPHIC RANGE.— Uppermost Eocene (Zone E16) to the end of Zone O4, with sporadic occurrences in Zone O5 (this study).

GEOGRAPHIC DISTRIBUTION.— Cosmopolitan. Beckmann (1957:89, text-fig. 14:7, 8) was the first to illustrate biserial morphotypes with a costate surface based on two morphotypes from lower Oligocene sediments (Cipero Formation) in Trinidad. Morphotypes with a shorter and wider test and greater apical angle most probably belong to the herein described species C. adriatica n. sp. Hornibrook (1990:368, pl. 1, fig. 1) also figured costate specimens from the lower Oligocene of Cuba, and Leckie and others (1993; pl. 1, fig. 14) provided SEM images of the same morphotype from lower Oligocene of the Ontong Java Plateau. In the Adriatic Sea and Syria this form is very common in Zone O1 and O2 and comprises up to 30% of the biserial planktonic populations in the small size fractions (63-125 μm).


Editors' Notes


Premec Fucek, V., Hernitz Kucenjak, M. & Huber, B. T. (2018). Taxonomy, biostratigraphy, and phylogeny of Oligocene Chiloguembelina and Jenkinsina. In, Wade, B. S., Olsson, R. K., Pearson, P. N., Huber, B. T. & Berggren, W. A. (eds) Atlas of Oligocene Planktonic Foraminifera. Cushman Foundation for Foraminiferal Research, Special Publication . 46(Chap 17): 459-480. gs V O


Chiloguembelina adriatica compiled by the pforams@mikrotax project team viewed: 30-11-2022

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