GEOLOGIJA 25/2, 229—236 (1982), Ljubljana
UDK 56:594.1(560) = 20
Three new species of the genus Gorjanovicia Polsak
from Kocaeli region (Northwestern Anatolia)
Sacit özer
Ege Üniversitesi Yerbilimleri Fakültesi
Jeoloji Bölümü, Bornova-Izmir
Abstract
Three new species (G. polsaki n. sp., G. kayae n. sp. and G. akyoli
n. sp.) of the genus Gorjanovicia Polsak have been determined from the
Campanian beds at Köseler village in Northwestern Anatolia.
Introduction
In the Kocaeli region, the Upper Cretaceous rocks are represented mainly
by rudistid limestones. K. Erguvanli (1949) has discovered rudistid lime-
stone with Campanian age in the Hereke-Gebze area. I. E. Al t mil (1968)
studied the geology of the Kocaeli-Hereke area and also found the rudists
in the Campanian limestone. O. Kaya (personal communication, 1981) has
recently made a detailed geologic investigation and collected many specimens
of rudistid fauna in the Upper Cretaceous of Kocaeli region.
The studied samples has been collected by Kaya from a location, approxi-
mately 2 km south of Köseler village (map reference G 23-a 4). The rock unit
that includes the material is of small-size reefy buildup of rudistids, at the base
of the well known Latest Cretaceous limestone-limy mudrock sequence of
Northwestern Anatolia. In the area of collection this basal unit unconformably
overlies the older Triassic beds.
The examination of this collection, of the genus Gorjanovicia Polsak revealed
the presence of the three new species. On the otherhand, new species of Gorjano-
vicia are associated with Vaccinites inaequicostatus Münster, Gorjanovicia cf.
costata Polsak, Gorjanovicia sp., Miseia sp. and Radiolitids.
Associated rudistid fauna and previous studies show that three new species
are of Campanian age.
230 :
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Fig. 1. Location map
Systematic Study
Classis LAMELLIBRANCHIATA
Ordo Rudistida Lamarck, 1819
Familia Radiolitidae Gray, 1848
Genus Gorjanovicia Polsak, 1967
Gorjanovicia polsaki n. sp.
PI. 1, Figs. 1, 2
Derivatio nominis: This new species is dedicated to Dr. Ante
Polsak who has made many valuable works on rudists.
Material : Holotype and paratype with lower valves.
H o 1 o t y p u s : Pl. 1, Figs. 1, 2, with lower valve is deposited at the Ege
Üniversitesi Yerbilimleri Fakültesi, Jeoloji Bölümü, with No. 2568.
Diagnosis : Siphonal bands concave, interband bulge. Ligamental pillar
inclined toward the anterior, head of ligament with two lobs.
Descriptio : Lower valve is conical. The diameter is 3,2 cm, the height
is 7.5 cm at posterior. The shell surface is covered with longitudinal costae of
1 mm width. Anterior siphonal band is 4 mm wide and concave. The wide of
posterior siphonal band is 6 mm and it has 3 costules. Interband is bulge and
4 mm wide. Probably, there are 2 costules on the interband. The ligamental
groove is 3 mm wide and decreases toward the end of cone. Thickness of the
outer layer is 4—5 mm. Ligamental pillar inclined towards anterior and it has
3 mm length. The head of ligament has two lobs and elongated towards anterior.
The posterior tooth B is more nearer to the ligament than the anterior tooth B'.
The anterior accessory cavity can be preserved.
Three new species of the genus Gorjanovicia Polsak from Kocaeli region 231
Discussio: G. polsaki n. sp. differs from the other species of the Gorja-
novicia by the position of ligamental pillar and the shape of head of the liga-
mental pillar.
Locus typicus: Holotype, Köseler village, Gebze, Kocaeli. Coordinate
on 1 : 25 000 scaled map is 25.20 :17.15.
Stratum typicum: Campanian,
Gorjanovicia kayae n. sp.
PI. 1, Fig. 3
Derivatio nominis: The new species is given the name after late
Dr. Orhan Kaya who has made a detailed geologic studies in the Northwestern
Anatolia.
Material : One sample with lower valve.
Holotypus: PI. 1, Fig. 3, with lower valve is deposited at the Ege Üni-
versitesi Yerbilimleri Fakültesi, Jeoloji Bölümü, with No. 2566.
Diagnosis : The anterior siphonal band as a groove, the posterior sipho-
nal band and interband flat. The ligamental pillar strong with a rounded head.
Descriptio : Lower valve is conical. The height of the lower valve
is 9 cm. In the cross-section, the diameter is 2,8 X 3,7 cm in size. The surface
is ornamented with 2—5 mm thick costae and grooves of 1—2 mm wide. The
anterior siphonal band as a groove, is 10 mm wide. The posterior band is 7 mm
wide and flat. It has 2 costae. Interband is flat and 8 mm wide. Probably, it has
3 costae. The ligamental groove is 5 mm wide and it has 3 costules. Outer layer
is 3—5 mm and it is recrystallized. The ligamental pillar is widened in a very
short distance and its head rounded off. The ligamental pillar is 2 mm long,
head of ligament is 1.3 mm wide.
Discussio: G. kayae n. sp., shows similarities with the shape of liga-
mental pillar to G. planinica Plenicar and G. n. sp. Plenicar. G. planinica has
concave siphonal bands and ridge-shaped interband. G. n. sp. Plenicar has nar-
rower siphonal bands (M. Plenicar, 1973). But, G. kayae n. sp. has groove
anterior siphonal band and flat posterior siphonal band and interband. G. kayae
n. sp. is similar with the ligamental pillar to G. planinica and G. n. sp. Plenicar,
but it completely differs with the structure of the siphonal region.
Locus typicus: Holotype, Köseler village, Gebze, Kocaeli.
Stratum typicum: Campanian.
Gorjanovicia akyoli n. sp.
PI. 2, Figs. 1—3, PI. 3, Figs. 1, 2
Derivatio nominis: This new species is dedicated to Dr. Eroi Akyol
who has made many valuable studies on palynology.
Material : Holotype, with well preserved upper and partly broken lower
valves, and one paratype represented only with lower valve.
H o 1 o t y p u s : Pl. 2, Figs. 1—3 and Pl. 3, Fig. 1 is deposited at the Ege Üni-
versitesi Yerbilimleri Fakültesi, Jeoloji Bölümü, with No. 2570.
232:
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Diagnosis : Lower valve with sharp longitudinal costae. Shell structure
partly lamellar, partly prismatic. Ligamental pillar well developed with a
triangular in shape at anterior. Upper valve well developed also, and the com-
missure makes an upward folding at siphonal region.
Descriptio : Lower valve is conical and the end of the lower valve
is curved towards the siphonal region. The height of the lower valve in siphonal
region is 6 cm, and at ligamental region 7,6 cm. The diameter at commissure
is 3,8 X 3,5 cm in size. The surface is ornamented with longitudinal costae. The
anterior siphonal band is 9 mm wide and flat. The posterior siphonal band is
5 mm and also flat. But, siphonal band E is narrower than the posterior siphonal
band S. Interband has 6 mm width, and as a groove. The shell structure is partly
lamellar, partly prismatic. In the cross-section, passing through 2 cm below the
commissure, ligamental pillar is 4 mm long, head of ligament is 1 mm wide. The
head of ligament is widened towards the anterior side as triangular in shape.
Anterior and posterior cardinal teeth are very well developed and anterior tooth
is bigger than the posterior tooth. The posterior accessory cavity is very smaller
than the anterior accessory cavity.
Upper valve is well developed and it is 10 mm in height. The commissure
makes an upward folding of 2 mm height at the siphonal region. Shell wall is
composed of very thin lamellae.
Discussio: G. akyoli n. sp. resembles with the structure of the siphonal
region to G. costata Polsak (A. Polsak, 1967; M. Pleničar, 1974). It
differs with the head of ligament from G. costata.
Locus  typicus:  Holotype, Köseler village, Gebze, Kocaeli.
Stratum typicum: Campanian.
Fig. 2. Comparison of the new species of Gorjanovicia Polsak
Three new species of the genus Gorjanovicia Polsalc from Kocaeli region
233;
Plate 1
1 Gorjanovicia polsaki n. sp.
lower valve, cross-section, holotype, 1 X
3 Gorjanovicia kayae n. sp.
lower valve, cross-section, holotype, 1 X
2 Gorjanovicia polsaki n. sp.
lower valve, cross-section, holotype, 3,5 X
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Plate 2
2 Gorjanovicia akyoli n. sp.
lower valve, cross-section, holotype, 1 X
1 Gorjanovicia akyoli n. sp.
lower and upper valves, anterior side, holotype, 1 X
3 Gorjanovicia akyoli n. sp.
lower valve, cross-section, holotype, 3,5 X
Three new species of the genus Gorjanovicia Polsak from Kocaeli region
2351
Plate 3
1 Gorjanovicia akyoli n. sp.
upper valve, external view, holotype, 1 X
2 Gorjanovicia akyoli n. sp.
lower valve, cross-section, paratype, 1 X
3 Miseia sp.
lower and upper valves, anterior side, 1 X
236 Sacit özer
Acknowledgment
I thank to Dr. E. A k y o 1 for his critical reading the manuscript and to dr. O.
Kaya who provided the material.
References
A111 n 11, I. E. 1968, Geologic investigation of the Izmit-Hereke-Kurucadag area.
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Erguvanli, K. 1949, Hereke pudinglerile Gebze taslarimn insaat bakimindan
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Pleničar, M. 1973, Radiolites from the Cretaceous Beds of Slovenia, Part I.
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