New Classopollis Species From Triassic-Jurassic Boundary In Northern Iraq

A new Classopollis species are described from Upper TriassicLower Jurassic Butmah Formation in borehole Tel-Hajar-1northern Iraq. These are Classopollis scabratus, Classopollis polygonus, Classopollis microgranulatus, Classopollis zonatus and Classopollis crescentus; these taxa reveal distinctive morphologic features which lead to regard them as a new species.


INTRODUCTION
The genus Classopollis is one of the important late Mesozoic fossil pollen grains and it has great importance in age determination and paleoecological interpretations of Mesozoic sediments. During the course of detailed palynological studies of Triassic and Jurassic strata of Butmah Formation in borehole Tel-Hajar-1 (41º 40' 20" L , 35º 50'40" W) southwest Mosul city, Iraq, many Classopollis species are recorded, these are: Classopollis itunensis, Classopollis meyerianus, Classopollis minor, Classopollis monostriatus,Classopollis murphy, Classopollis simplex, Classopollis triangulus, Classopollis torosus in additio to other new species of this study: (Classopollis scabratus, Classopollis polygonus, Classopollis microgranulatus, Classopollis zonatus and Classopollis crescentus) which showed very distinctive morphologic features. I expect that these new species will have a biostratigraphical and Paleoecological impliations. The purpose of this paper is to document these species systematically and to relate their occurrence to the palynostratigraphic sequences.

STRATIGRAPHY (Material and Methods)
This study is based on pollen grains extracted from samples representing part of Butmah Formation penetrated in borehole Tel-Hajar -1 from ( 4048-3506 m.) levels. Dunnington (1953;in Bellen et al., 1959) first described the Butmah Formation from borehole Butmah-2 southwest Mosul city (Since Butmah Formation has not described from surface exposures). The rocks penetrated in this interval are described as heterogeneous aggregate of sediment of calcareousargillaceous and evaporitic rock suites (Fig. 2). According to (Jassim and Goff, 2006) the upper part (200m.) of the Butmah Formation in the type section consists of oolitic and detrital limestone with beds of argillaceous limestone, shale and anhydrites. The middle part (180m.) is oolitic, argillaceous and dolomitic with sandstone and shale bed. The lower part (120m.) is composed of limestone with bedded anhydrite. The lithofacies and faunal assemblages indicate that Butmah Formation was deposited in shallow water lagoonal and sabkha environments. Most samples were productive of palynomorphs. The undoubted indigenous palynoflora of the rock indicates Late Triassic ((Rhaetian)-Early Jurassic((Hettangian-Sinemurian) age for the Butmah Formation.

Circumpolles pollen The pollen genus Classopollis Pflug, 1953
Pollen grains are referable to the genus Classopollis Pflug are found in strata ranging in age from Permian to Eocene. The Classopollis producing coniferous plants (Cheirolepidiaceae) were particularly abundant and widespread during the Jurassic and Cretaceous at low to mid palaeolatitudes. They extended over a broad range of habitats and flourished under warm to hot subtropical to tropical climates, (particularly under dry, especially semiarid to arid, conditions) and the abundance of the pollen produced by them is considered to be a reliable climatic and biostratigraphic marker. Representatives of the genus Classopollis commonly dominate plant-microfossils assemblages of the Rhetian and Liassic.

Remarks:
The use of the generic names Circulina Malyavkina, 1949, Corollina Malyavkina, 1949and Classopollis Pflug, 1953 in the literature has led to a great confusion amongst palynologists. Klaus (1960) and Cornet andTraverse (1975) regarded Classopollis as a junior synonym of Corollina. Traverse (2004) proposed conservation of the name Classopollis against Circulina and Corollina because the original description of Classopollis Pflug, 1953 was provided with good illustrations. In the present study all forms will be treated under the generic name Classopollis.

GENERIC DIAGNOSIS Pflug's (1953)
Generic diagnosis of Classopollis was "tricolporate, rarely tetracolporate. Rimula well developed, germinales gaping. Poles never quite identical in appearance." In the text (pp. 73-74), he illustrated the position of what he termed the "rimula", or main colpus. The exine structure of many specimens also appears to support the theory that Classopollis possesses characters in common with both gymnosperms and angiosperms. Our figure 5 on plate 1 illustrates a grain from the Neocomian of Alberta, which belongs to the genus Classopollis and has the appearance of a tricolpate grain with a two-layered tectate exine. Oblique squashing caused this misleading appearance. Genus Classopollis Pflug, 1953, emended, Pocock and Jansonius Diagnosis: Pollen grains, distally monoporate, ovoid, spherical, or flatly acorn-shaped, exine two-layered, exoexine absent or much reduced over a circular area surrounding the distal pole and absent or reduced over a triangular area with its center at the proximal pole, intexine frequently bearing a reduced trilete scar, which has no germinal function, at the proximal pole; exine always ornamented by striations in a band or girdle surrounding the equator and interrupted (if at all) at only one point; the band usually, but not always, marking a zone of exinal thickening. Diagnosis:Pollen grains, spherical shape,Subequatorial Sulcus obvious sometimes become indistinct. A triletes scar (5 -9) μm at length. Distal pore (4-6) μm Wall thickness (1) μm has red brownish in color. Ornamentation: Minute grana (1) μm long, unevenly distributed with some parts of the pollen surface smooth .No equatorial striations. Size: 25(32.5)40μm from (10) specimens.

Comparison:
Our specimens compare very closely in structure to C.torosus, but differ significantly in size and distributions of the ornamentation elements on the exine and the absences of equatorial striations.

Comparison:
Our specimens compare very closely in structure to C.torosus but differ significantly in no equatorial striation and the appearance of compression fold (crescent shape) near subequatorial sulcus which parallel the amb of pollen grain.