The Karakaya Complex is a tectonostratigraphic term for a highly deformed and partly metamorphosed clastic and volcanic series of Permian and Triassic age on the Biga Peninsula, northwestern Turkey [25]. The term ‘Karakaya’ was initially introduced by Bingol [7], as the ‘Karakaya Series’, for a slightly metamorphic succession at Karakaya Hill to the south of the Beyobasi village in the Edremit area. Later, the name ‘Karakaya Formation’ was applied by Bingol et al. [8] to include the ‘detrital unit with Permian olistoliths’ and the ‘spilites with Permian olistoliths’ [31]. The Karakaya Complex is generally subdivided into two parts, a lower and an upper one [25].

The Upper Permian rocks within the Karakaya Complex are known from previous studies, and many authors have reported the blocky nature of the Carboniferous and Permian strata present [2], [4], [8], [19], [29] and [30]. There are different opinions about the provenance of these blocks [2], [4], [20] and [29]. According to Altiner et al. [4], Upper Palaeozoic (Carboniferous–Permian) carbonate exposures of non-metamorphosed siliciclastic rocks of the Karakaya Orogen are olistoliths deposited during the Late Triassic. The likely provenance of the blocks is from the south and from the northern margin of a carbonate platform of Gondwanan origin. The wide range of the ages of carbonate blocks from Visean to the Latest Permian and the harmony of their chronostratigraphic order with the Carboniferous and Permian stratigraphy of the Taurus carbonate platform are proposed as evidence for their southern origin by these authors.

Previously, many rift-related models were proposed for the evolution of the Karakaya units [2], [8], [15] and [26]. Goncuoglu et al. [14] have reported synsedimentary radiolarian cherts (Changhsingian in age) within the proximal turbidites and olistrostromes of the Karakaya Complex, and they concluded that the rifting of this basin within the Sakarya Composite Terrane [13] took place between the deposition of the Midian platform carbonates (e.g., [31]), and that of the Changhsingian rift-related sediments and volcanism.

The present new taxa of small foraminifers are described from the Upper Karakaya Complex, and are known in northwestern Turkey only from the Asagicakallar locality, where Permian rocks are found as olistoliths in debris flow deposits of Triassic age (Fig. 1). The basal part of the olistolith is composed of thin- to medium-bedded grey limestone. Above is grey, medium-bedded brecciated limestone with abundant fusulinids and algae. The middle part of the section consists of grey, fusulinid, and hemigordiopsid-bearing limestone. The upper part of the olistolith is represented by yellow–light grey, thin- to medium-bedded clayey limestone. The total thickness of the olistolith is 59 m (Fig. 2).

The author follows the systematic classification of Loeblich and Tappan [22]. All holotypes and paratypes are stored in the collection of the Natural History Museum of MTA (General Directorate of Mineral Research and Exploration of Turkey), Ankara, Turkey, under No. MTA2002/CO3.

Order Foraminifera d’Eichwald [11]

Emended diagnosis. Test-free, globular proloculus followed by a long undivided tubular chamber. Central cavity of tube circular or slightly quadrangular in transverse section. Marked longitudinal rounded or acute costae on the test surface. Wall is calcareous microgranular, sometimes with fine alveolar structures and very finely agglutinated particles. Aperture simple terminal opening.

Included genera. Chitralina Angiolini and Rettori [5], Giraliarella Crespin [9] and Rectoformata gen. nov.

Discussion. The Chitralinidae distinguish themselves from the original diagnosis of Angiolini and Rettori [5] by having a circular central cavity, longitudinal acute costae and a very finely agglutinated wall. The new emended family differs from the other families included in the superfamily Earlandiacea Cummings [10] by having rounded or acute longitudinal costae on the test surface.

Stratigraphic and geographic range. Permian of Karakorum (Pakistan), western Australia, and northwestern Anatolia (Turkey).

Genus Rectoformata gen. nov.

Type species. Rectoformata tekini sp. nov.

Derivation of the name. From the Latin, recto, straight; formata, shaped, in reference to the straight shape of the test.

Diagnosis. Test-free, globular proloculus followed by a long undivided tube with circular central cavity. Septation or pseudoseptation absent. Test surface characterized by four or five longitudinal acute costae. Wall is calcareous microgranular with fine alveolar structures. Aperture simple terminal opening.

Composition. Rectoformata tekini sp. nov. and Rectoformata acari sp. nov.

Comparisons. The new genus differs from the Middle Permian ( = Guadalupian) genus Chitralina Angiolini and Rettori [5] by having a calcareous microgranular wall with fine alveolar structures (Figs. 3.1–3.7) and the presence of a circular central cavity, four or five longitudinal acute costae. Chitralina Angiolini and Rettori [5] is characterized by a triangular to quadrangular test in transverse sections, a calcareous dark uniform microgranular wall, a slightly quadrangular central cavity and longitudinal rounded costae. Rectoformata gen. nov. is also distinguished from the similar species Giraliarella Crespin [9] by having a calcareous microgranular wall with a fine alveolar structure, whereas Giraliarella Crespin [9] has a very finely agglutinated wall (Fig. 3 and Fig. 4).

Stratigraphic and geographic range. Middle Permian ( = Guadalupian), Midian ( = Capitanian) of northwestern Anatolia (Turkey).

Rectoformata tekini sp. nov. (Figs. 3.1–3.7)

Derivation of the name. This species is named after Associate Professor Dr. U. Kagan Tekin (Hacettepe University), in honour of his contributions to the knowledge of Mesozoic Radiolarian biostratigraphy.

Holotype. Sample MTA2002/CO3–02 CO 1–1-3 (Fig. 3.1).

Paratypes. MTA2002/CO3-02 CO 9-2-1, MTA2002/CO3-02 CO 5-2-1, MTA2002/CO3-02 CO 1-2-2, MTA2002/CO3-02 CO 1-2-6, MTA2002/CO3-02 CO 9–1-2, MTA2002/CO3-02 CO 11-1-1.

Type locality. Southwest of Asagicakallar village, south of Balya district, Balikesir, NW Turkey.

Type level. Midian ( = Capitanian).

Material. Eight specimens (only seven specimens illustrated herein).

Diagnosis. Rectoformata with quadrangular transverse section and calcareous microgranular wall with fine alveolar structure.

Description. Test-free, elongate, globular proloculus followed by a long undivided tubular chamber with circular central cavity, increasing in width during the growth. Quadrangular test, characterized by the presence of four longitudinal acute costae on the test surface. Septation or pseudoseptation not seen in longitudinal sections. Calcareous microgranular wall with fine alveolar structures. Aperture simple terminal opening.

The new genus Rectoformata appears for the first time in the Middle Permian (Guadalupian) and represents a descendant of Earlandia Plummer [27]. Angiolini and Rettori [5] discussed the phylogenetic relationships between Chitralina Angiolini and Rettori [5] and Rectostipulina Jenny-Deshusses [17], and they claimed that both were derived from Earlandia. The two genera can be distinguished based on the wall. The wall of Chitralina is simple and microgranular, whereas that of Rectostipulina is hyaline radial. However, the genus Rectostipulina was attributed to the Nodosariida, family Syzraniidae by Vachard in [32]. Recently, Groves et al. [16] have also indicated to the similarity of the Rectostipulina with Syzrania Reitlinger [28] and other syzraniids. In this case, the validity of the phylogeny of Angiolini and Rettori [5] is doubtful.

Rectoformata gen. nov., Giraliarella Crespin [9] and Chitralina are homeomorphic genera, with the main differences among them being wall structure. The wall of Rectoformata gen. nov. is calcareous microgranular, with fine alveolar structures, whereas Chitralina has a simple dark microgranular wall, and Giraliarella contains a very finely agglutinated wall with large quantities of cement. Giraliarella also differentiates itself from the other genera by a more complex morphology, due to the development of transverse growth constrictions.

Earlandia appears for the first time in the Silurian (Loeblich and Tappan [22]) and Chitralina in the Kubergandian ( = Roadian) [5], in both cases earlier than the first appearance of new genus Rectoformata. It is clear that the new genus differs from the homeomorphic Guadalupian genus Chitralina mainly by its calcareous microgranular wall with fine alveolar structures. Fine alveolar structure in the wall of the new genus is possibly indicative of an evolutionary stage in this lineage. The possible lineage can be formulated as Earlandia–Chitralina–Rectoformata.

Chitralina and Rectoformata are of Middle Permian (Guadalupian) age. Chitralina undulata Angiolini and Rettori [5] is restricted to the Kubergandian/Late Murgabian–Midian. The new species, Rectoformata tekini and Rectoformata acari, are only known from the Middle Permian ( = Guadalupian), Midian ( = Capitanian) deposits of northwestern Anatolia (Turkey) and are not known from older or younger strata.