Ammobaculites agglutinans (d'Orbigny, 1846) emend. Bartenstein, 1952



Fig. 70. 1- Type figure of d'Orbigny (1846); 2- Lectotype of A. agglutinans, from Loeblich & Tappan (1964);
3- Lectotype of A. agglutinans from the d'Orbigny Collection in Vienna, from Papp & Schmidt (1985).


ORIGINAL DESIGNATION: Spirolina agglutinans d'Orbigny, 1846.

TYPE REFERENCES:
d'Orbigny, A., 1846. Foraminifères fossiles du bassin tertiaire de Vienne, (Autriche). Gide et Comp, Paris France, p. 137, pl. 7, figs. 10-12.
Bartenstein, H., 1952. Taxonomische Bemerkungen zu den Ammobaculites, Haplophragmium, Lituola und verwandten Gattungen (For.). Senckenbergiana, 53, p. 318, pl. 1, fig. 1a-c; pl. 2, figs 10-16.
Papp, A., & Schmidt, M.E., 1985. The fossil foraminifera of the Tertiary basin of Vienna, revision of the monograph by Alcide d'Orbigny (1846). Abhandlungen des Geologischen Bundesanstalt, 37, 1-311; p. 54, pl. 45, figs. 6-9. [Lectotype].
Kaminski, M.A. & Kuhnt, W. 1991. Depth-related shape variation in Ammobaculites agglutinans (d'Orbigny). Annales Societatis Geologorum Poloniae, 61, 221-230.

TYPE SPECIMEN: The lectotype, designated by Papp & Schmidt (1985), is housed in the micropaleontological collections of the Geologische Bundesanstalt in Vienna. The specimen is registered as GBA 1981/03/196. Additional metatype specimens from the d'Orbigny Collection are housed in the micropaleontological collections of the U.S. Natural History Museum, Washington, D.C.

TYPE LEVEL: Middle Miocene.

TYPE LOCALITY: Clay pits in the town of Baden, near Vienna, Austria.

DIAGNOSTIC FEATURES: Test robust, initially planispiral, later uniserial. Planispiral portion is involute, with slightly depressed umbilicus and four or five chambers in the final whorl. Uniserial portion is rectilinear and round in cross section, extending tangentially from the initial portion, with as many as 4 chambers. Chambers in the uniserial portion are broader than high, and round in cross section. Sutures are straight and depressed in the uniserial part, indistinct in the uniserial part. Aperture terminal, a single oval or round opening without a lip. Wall medium to coarse, with poorly sorted grains, consisting mainly of quartz, but may contain some calcareous material.

SIZE: The metatypes in the USNM are up to 0.8 mm in length, with the width of the coiled part 0.45 to 0.60 mm. The uniserial portion is 0.30 mm in width.

SYNONYMS: none verified.

OBSERVED OCCURRENCES: Ammobaculites agglutinans was originally described from the Middle Miocene of the Vienna Basin, and has subsequently been reported from rocks ranging in age from Jurassic to Recent. In his revision of the foraminiferal assemblages from d'Orbigny's locality, Marks (1951) listed it as Haplophragmium agglutinans. It has also been found in Miocene sediments from offshore Cabinda (West Africa) and from the Chechiş Formation of the Transylvanian Basin (Preece, 1999), in the Oligocene at ODP Site 1148 in the South China Sea (Kuhnt et al. 2002), and in the Paleocene Hieroglyphic beds of the Dukla Unit of the Polish Carpathians (Bąk, 2004).
In the modern ocean, A. agglutinans has been reported from neritic to abyssal depths by numerous authors. Brady (1884) first applied the designation Haplophragmium agglutinans to the Recent forms, but also he reported it from the Paleozoic. Brady listed it from nine CHALLENGER stations in the North Atlantic ranging in depth from 530 to 2750 fathoms; from two stations in the South Atlantic (2200 and 2900 fathoms); and from 12 stations in the Pacific from 2 to 3125 fathoms. Balkwell & Wright (1885) reported A. agglutinans from 17 fathoms off Skerries, Ireland and from 50 fathoms in the Lambay Deep, NE of Dublin, Ireland. Goes (1894) illustrated a specimen from 1,704 m depth in the North Atlantic. Cushman (1920) reported it from numerous ALBATROSS stations in the North Atlantic, ranging in depth from 27 to 2369 fathoms. He noted it was common in many stations. Cushman (1921) recorded it from 17 ALBATROSS stations from 14 to 750 fathoms depth in the Philippine archipelago. Cushman noted it was most common above 300 fathoms in these samples. Earland (1936) listed it from five stations in the Weddell Sea between 1131 and 2550 fathoms. Harloff & Mackensen (1997) recorded its upper depth limit as 1200 m in the Argentine Basin and Scotian Sea. It is one of the dominant species in the deep Argentine Basin, beneath the CCD. In the South China Sea, A. agglutinans is mostly found at stations below a depth of 2800 m (Hess, 1998).
We have observed that A. agglutinans occurs mainly in areas with coarse substrate along the continental margin off Nova Scotia. Thomas (1985) and Schröder (1986) recorded it from bathyal to upper abyssal depths on the Nova Scotian continental slope, but it was not observed in samples from the Hatteras and Nares Abyssal Plains. Specimens which compare well with the Neogene specimens of A. agglutinans also occur in the Upper Cretaceous of the Labrador Margin wells. However, the distribution of A. agglutinans in the Cretaceous and Paleogene deep-water assemblages is more restricted than in the modern ocean. It is rare in the "flysch-type" assemblages, and we have not encountered A. agglutinans in Late Cretaceous to Paleogene abyssal assemblages, or in "Scaglia-type" assemblages from deep-water limestones. In the Austrian Molasse basin Cicha et al. (1998) reported its range as Late Eocene to Middle Miocene.

KNOWN STRATIGRAPHIC RANGE: Late Cretaceous to Recent.

BATHYMETRY: Outer neritic to abyssal.

REMARKS: Ammobaculites agglutinans is the type species of the genus Ammobaculites, so it is necessary to establish the validity of the proposed types. In his study of this species, Bartenstein (1952) illustrated specimens from the d'Orbigny Collection. A specimen from the Miocene of Austria, was illustrated by Loeblich & Tappan (1964) and designated the lectotype, but it is unclear where this specimen was collected. Papp & Schmidt (1985) uncovered and re-illustrated d'Orbigny's original specimens housed at the GBA in Vienna and designated a lectotype. We regard the specimen illustrated by Papp & Schmidt as the true lectotype. The 17 paralectotype specimens in the d'Orbigny Collection in Vienna have between one and four uniserial chambers. The specimens are coarsely agglutinated, with calcareous particles incorporated into the wall, including fragments of other foraminiferal tests.
Brady (1884) first applied the term H. agglutinans to describe the common Recent deep-water variety, and he noted the large variation in both the size and bathymetric range of this species. These bathyal to abyssal forms compare well with d'Orbigny's types, but commonly display more variability in the size of the agglutinated grains, and may possess more chambers in the uniserial portion of the test. Cushman (1920) provided a detailed description of the modern deep-water form:

"Test elongate, early portion closely coiled, planispiral, of one or usually more coils, each with five to seven chambers, later portion uncoiled, sub-cylindrical, made of a linear series of chambers, in adult specimens making up the larger portion of the test; wall rather coarsely arenaceous, somewhat variable in its surface, usually roughened but occasionally fairly smooth. Aperture in the early portion slit-like, at the base of the apertural face; in the uncoiled portion the aperture is in the middle of the terminal face and is rounded. Color variable, usually gray."

In the microfossil collections of the USNM, 28 slides of A. agglutinans from Cushman's Atlantic ALBATROSS samples are preserved in the collection of secondary types. When these slides are arranged in order of increasing depth, a regular progression of morphologic traits is observed. In order to record ecophenotypic variation related to bathymetry, the following traits were measured: length of the test, width across the initial spire, width across the uniserial portion, and number of uniserial chambers. The data are presented in the following plots:


Figure 70-2. Measured parameters of ALBATROSS specimens from the North Atlantic preserved in the Cushman Collection, arranged according to depth. All measurements were taken using an optical micrometer.


The 124 specimens preserved in the Cushman collection is certainly not a rigorous statistical assemblage, since we have no way of determining whether there was bias in the collecting procedure. Nevertheless, two ecophenotypic trends in mophology are evident, which enable us to separate a neritic to bathyal population from an abyssal one. First, there is an increase in the length of megalospheric individuals with increasing depth. Specimens from neritic and bathyal stations rarely possess more than four uniserial chambers, whereas the specimens from abyssal stations (below 2500 m) are larger (up to 2.7 mm), and may possess as many as nine uniserial chambers. A Student's t-test performed on these data revealed that the size differences are significant (P<0.001). The second depth-related trend is observed in the diameter of the initial spire. In particular, the size difference between megalosphaeric and microsphaeric individuals is more distinct in the abyssal morphotype (the distribution of measurements from the deep stations is bimodal). Another difference is observed in the nature of agglutinated grains. The bathyal morphotype may incorporate calcareous particles, whereas the abyssal form uses only fine quartz grains bound by a brownish organic cement.


Figure 70-3. Representative specimens of A. agglutinans from Cushman's ALBATROSS samples. Numbers indicate depth of station in fathoms. All specimens drawn to the same scale. Drawings made by W. Kuhnt.


ILLUSTRATIONS: Plate 70 - Ammobaculites agglutinans d'Orbigny emend. Bartenstein
Figs. 1a-4b. Middle Miocene, Baden Austria, Metatypes from the d'Orbigny Collection (USNM); Fig. 5. Recent, Nova Scotian continental rise, 4125 m; Fig. 6. Recent, Nova Scotian continental slope, 2995 m; Fig. 7. Recent, Nova Scotian continental slope; Fig. 8. Maastrichtian, Labrador Margin, Roberval K-92 well.