Schubertina Marshall, 1969

Davydov, Vladimir I., 2011, Taxonomy, nomenclature, and evolution of the early schubertellid fusulinids, Acta Palaeontologica Polonica 56 (1), pp. 181-194 : 184-186

Genus Schubertina Marshall, 1969

1937 Eoschubertella Thompson, 1937: 123–124 (pars).

1964 Eoschubertella Thompson ; Loeblich and Tappan 1964: C401 (pars).

1969 Schubertina gen. nov.; Marshall 1969: 121.

1969 Pseudoschubertella gen. nov.; Marshall 1969: 124–125.

1988 Eoschubertella Thompson ; Loeblich and Tappan 1988: 258–259 (pars).

1988 Quydatella Liem, 1966 ; Loeblich and Tappan 1988: 257–258 (pars).

1996 Eoschubertella Thompson ; Chediya in Rauser−Chernousova et al. 1996: 86 (pars).

2007 Grovesella Davydov and Arefifard, 2007: 5–6 (pars).

Type species: Schubertina circuli Marshall, 1969 , Bird Spring Formation, Clark County Nevada; Horquilla Limestone ; Blue Mountain , Arizona; early Desmoinesian (middle Moscovian), Pennsylvanian .

Type material: Schubertina circuli Marshall, 1969: 122–123 , pl. 1: 38–41 (holotype fig. 39; refigured herein as Fig. 2T) that is a junior syn− Arrow Canyon section, Nevada. R. SUI 114222, axial section of paratype, sample 9476_840_1−2, Bird Spring Formation, Artinskian, Arrow Canyon section, Nevada. U. SUI 114227, axial section of paratype, sample 9476_840_2−2, Bird Spring Formation, Artinskian, Arrow Canyon section, Nevada. V. SUI 114226, axial section of paratype, sample O−1−101−2, Kalinovo section, O 1 Limestone, middle Kasimovian, Donets Basin, Ukraine. W. SUI 114225, axial section of paratype, sample Gurk_ M−9_21−2a, Gurkova section, M 9 Limestone, upper Moscovian, Donets Basin, Ukraine. O, S, X. Schubertina bluensis ( Ross and Sabins, 1965) . O. YPM 23432, axial section of holotype, from Ross and Sabins (1965: pl. 21: 29), locality DC−7, Dos Cabezas Mountains, Arizona, USA. S. YPM 22057, axial section of paratype, from Ross and Sabins (1965: pl. 21: 28), locality BM−3, Dos Cabezas Mountains, Arizona, USA. X. YPM 22057, axial section from the same thin−section as V; Horquilla Limestone, Middle Pennsylvanian, Arizona. T, Y, Z. Schubertina curculi Marshall, 1969 . T. SUI 75266D, axial section of holotype, from Marshall (1969: pl. 1: 39), 26S−12E. Y. SUI 75272E, axial section of paratype, from Marshall (1969: pl. 1: 38), FCM 268− 9L. Z. SUI 75273H, axial section of paratype, from Marshall (1969: pl. 1: 40), 26S−3H. Mountain Springs Pass section, Middle Pennsylvanian, S. Nevada. AA. Pseudoschubertella fusiformis ( Marshall, 1969) (type species of Pseudoschubertella Marshall, 1969 ), SUI 75449H, axial section of holotype, from Marshall (1969: pl. 2: 1), FCM 302−1H, Mountain Springs Pass section, Middle Pennsylvanian, S. Nevada. Scale bars 0.1 mm.

doi:10.4202/app.2010.0026

onym of Eoschubertella bluensis Ross and Sabins, 1965: 184 , pl. 21: 28 (paratype YPM 22057) and 29 (holotype YPM 23432) = Schubertina circuli Marshall, 1969: 122–123 , pl. 1: 38–41.

Description.—Test small subglobose−ovoid to ovoid−fusiform, with two, to three and a half volutions. The initial volution always coiled at large angle in respect to the following volutions. The initial chamber is relatively large with outside diameter 30–70 µm. The proloculus/test ratio is 1:4 to 1:6 as opposed to 1:10 to 1: 30 in Schubertella . Volutions coiled loosely, except for the first one that is tight. Chomata are very small to nearly undetectable. Septa are straight throughout. Wall is thin, often poorly differentiated. In well preserved specimens it is two−layered protheca with a thin, dark tectum and thicker, light lower layer (tectorium). A discontinuous upper tectorium observed in some specimens.

Remarks.—The author agrees with Groves (1991) who considered Schubertina circuli Marshall, 1969 as a junior synonym of Eoschubertella bluensis Ross and Sabins, 1965 . Both species possess quite similar morphology such as a subglobose outline, similar size of the proloculus, and overall test, character of coiling, and straight septa. Besides, they both appear close to the same chronostratigraphic horizon (middle Pennsylvanian). However, according ICZN, Article 67.1.2. “…the name of a type species remains unchanged even when it is a junior synonym or homonym, or a suppressed name.” Thus, the type species of Schubertina is S. circuli Marshall, 1969 but at the same time it is a synonym of Schubertina bluensis ( Ross and Sabins, 1965) and should be used under this taxonomy.

Schubertina differs from Schubertella in its much smaller overall test size, subglobose to ovoid outline, relatively large proloculus, smaller number of volutions (two−three in Schubertina and four−six in Schubertella ), two−layered wall, poorly developed secondary deposits and straight septa. Schubertella possesses a fusiform outline, at least four volutions, relatively small proloculus, three−layered wall, always prominent chomata and weakly fluted septa at the polar ends. Wall structure in both genera could appear similar in cases of poor preservation.

Schubertina is closely related to and somewhat resembles Grovesella Davydov and Arefifard, 2007 . Their comparison is provided below in the re−description of Grovesella .

Stratigraphic and geographic range.— Schubertina similarly to Schubertella is distributed globally within the tropics−subtropics. It has been documented in the upper lower Bashkirian, Askynbashian Horizon in the Urals ( Sinitsyna and Sinitsyn 1987), Donets Basin ( Manukalova−Grebenyuk et al. 1969) and Timan−Pechora ( Nikolaev 2005) and in early Atokan (late Bashkirian) in North America ( Groves 1986, 1991). The upper range of Schubertina is not clear at the moment. Some forms that can be considered as Schubertina are reported from Wordian (early Midian), Capitanian (late Wordian) and Lopingian ( Skinner and Wilde 1966; Leven 1998a).