Type of wall: Microperforate, bilamellar, the wall is 3-3.5 μm thick, the inner layer is very thin (0.4-0.5 μm), the outer layer has a submicron-scale granular (blocky) texture, granule size is 0.2-0.35 μm; this has an ototara-type wall (see Chapter 15, this volume); surface is smooth to finely pustulose near the aperture; the wall is evenly perforated by pores that are usually about 0.8 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, slightly lobulate; globular chambers increase moderately in size, usually 11-12, and sometimes up to 14 in adult specimens, initial chambers sometimes slightly twisted, sutures depressed, slightly oblique toward apical axis; aperture a relatively small symmetrical low arch off-centered from the base of the final chamber, bordered on one side by a narrow collar. Apical angle is about 45-50°.

DISTINGUISHING FEATURES.— Distinguished from C. cubensis and C. adriatica by the absence of costae on the wall surface texture, and from C. ototara by its smooth microperforate wall texture. This species is morphologically convergent with Streptochilus martini but is distinguished by having a lower apertural arch (compared with the high asymmetrical arch of S. martini), lack of a tooth-plate, generally smaller test and more inflated chambers.

DISCUSSION.— The specimens of Chiloguembelina andreae presented in this work were found in the Adriatic Sea and in Syria. They are characterized by having a smooth test surface, globular chambers and a small aperture, bordered on one side by a narrow collar. The first description of biserial planktonic foraminifera with a smooth surface was by Andreae (1884) for his species Textilaria gracillima: “Very small test show 7-8 chambers, distinct and deep sutures. The four youngest chambers are inflated, spherical, and each is slightly different in size. The test is three times longer than wide. The shell is smooth, glossy and very finely perforate. The species is very rare.” Unfortunately the holotype was lost in a fire in Strasbourg and the type section, described as a wood path between Sentheim and Aue (Lauw) in Upper Alsace, cannot be located. Our search for material from the C. gracillima type locality, including searches of Cushman residues from Oligocene localities from the Alsace region that were studied by Andreae, has met with no success. Hence we must regard gracillima as nomen dubium non conservandum. However, the name Chiloguembelina gracillima in Middle and Eastern Europe has been often used for biserial forms with a pustulose test surface (Cicha and others, 1998; Hamrsmid and Rögl, 2000). This form may belong to C. ototara (F. Rögl, personal communication). Bombita and Rusu (1981) and Andreyeva-Grigorovich and others (2008) also recorded the presence of C. gracillima, but without illustrations. Due to the uncertainty of the test surface of C. gracillima and to avoid taxonomic confusion, we have decided to name a new species for the smooth-walled forms. One of the specimens illustrated by Huber and others (2006) as ototara is assigned to andreae in this work because it lacks pustules on the earlier chambers.

PHYLOGENETIC RELATIONSHIPS.— Probably descended from Chiloguembelina ototara during the latest Eocene.

GEOGRAPHIC DISTRIBUTION.— Very rare in mid- and low latitudes. Their rare appearance in lower Oligocene sediments (Zone O1 and O2) is a consequence of the small test size, very thin wall and consequently high dissolution susceptibility (Pl. 17.2, Figs. 13, 20). Exceptionally well-preserved material from the Jihar-9, Jazal-2 and Jazal-3 wells in the Palmyride region (Syria) contains more specimens of C. andreae than sediments of poor or moderate preservation.

STABLE ISOTOPE PALEOBIOLOGY.— No data available.

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