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Areoligera gippingensis

Areoligera gippingensis, Jolley, 1992, p. 26-31

synonyms of Areoligera :
senonensis: 1969, Lejeune-Carpentier; Gocht: text-fig. 40a, (not b), c-f, ?text-fig. 41 a-c, pl. 8, figs 5-9 (not 4). ; 1976, Lejeune-Carpentier; Schumacker-Lambry & Chateauneuf: pl. 3, fig. 5.
cf. senonensis: 1985, Lejeune-Carpentier; Heilmann-Clausen: pl.14, figs 4, 5
coronata: 1976, (O. Wetzel) Lejeune-Carpentier; Schumacker-Lambry & Chateauneuf: pl. 3, figs 3, 4.
cf. coronata: 1978, (O. Wetzel) Lejeune-Carpentier; Schumacker-Lambry: pl. 1, fig. 5.; 1985, (O. Wetzel) Lejeune-Carpentier; Heilmann-Clausen: pl. 14, fig. 3.
synonym: Cyclonephelium ordinatum: 1978, Williams & Downie; Schumacker-Lambry: pl. 3, fig. 13.

Holotype: Jolley 1992: Pl. 1, figs 1,2; Text-fig. 2a
Locus typicus: B.G.S. Ormesby A Borehole, Norfolk, England
Stratum typicum: Ormesby Clay (Ormesby A Borehole) of Knox et al., (1990).
Occurrences: In the East Anglian sections restricted to the Thanet Beds and Ormesby Clay. In Kent in the Thanet Beds; similar abundances are recorded in sediments of the Montrose Group of the East Shetland Platform, North Sea.

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Original description: [Jolley, 1992, p. 26-31]:

Diagnosis:
Large skolochorate dinoflagellate cysts, circular in outline, dorso-ventrally compressed, cyst wall of autophragm only.
Processes are grouped into penitabular complexes, are parallel sided, straight (length is 1/2 to 3/4 of the body diameter), solid and ribbon-like, tapering distally before a flared tip. Complexes of processes composed of groups of up to twelve, connected by septa not exceeding 1/2 process length. Median trabeculae may exceed the processes in width by eight times and bear short distal processes unrelated to a proximal process; distal trabeculae are not present. Soleate process complexes occur on paraplates 1", 2", 3", 4", 5" reflecting the anterior and lateral parasuture margins and on paraplates 1"', 2"', 3"', 4"' and 5"' delineating posterior margins. Annular complexes occur on paraplates 1-4', 1"" and in some on paraplate 5"'; linear process complexes occur on dorsal cingular paraplates and on the posterior intercalary paraplate. Complex not present on paraplate 6"', an arcuate to fragmentary soleate complex may occur on paraplate 6".
Paratabulation formula; 1-4', 1-6", 1-6c, 1-6"', 1p, 1"" in Kofoid notation.
Principle archaeopyle parasuture angular; archaeopyle Type tA (1"-4") operculum free. Accessory archaeopyle sutures present, sulcal notch prominent on ventral surface between paraplates 1" and 6".

Description:
Skolochorate dinoflagellate cysts with a circular outline to the body when the dorsal or ventral surfaces are uppermost (dorso-ventral compression). Rare lateral compressions (ie. when the margins of the dorsal and ventral surfaces are uppermost) show the lenticular shape of the cyst. The antapex may be bilobed in some specimens. Cysts measure from 45 µm (51.6 µm) 59 µm in overall width to 32 µm (36.8 µm) 42 µm in overall length, (based on 20 specimens, including processes). The cyst wall is composed of autophragm only and is smooth to weakly granular. The wall supports several penitabular annular, soleate, arcuate and linear process complexes. These complexes are absent on paraplates 1c, 5c, 6c, 6"' and the sulcal paraplate series. The soleate process complexes on the precingular paraplate series (1-5", and 6" in some specimens) define the anterior margin of the paraplate (see figure 2), in contrast to those in the postcingular paraplate series (1-5"') which define the posterior margin of the paraplate. Detached opercula show that an annular complex is present on paraplate 3'. Complexes on paraplates 1', 2' and 4' may be annular or soleate (Text-fig. 2). An annular complex is developed on paraplate 1"".
Up to twelve solid processes are present on each complex. Processes are long and simple, ranging in length from 15 µm (24 µm) to 33 µm. While the majority of processes are parallel sided or taper slightly to the distal tip, they occasionally branch and may thicken locally. This branching usually occurs at the mid point or distal tip of the processes where it gives the appearance of a trifurcate or bifurcate process (Pl. 1, fig. 3). Proximally, the processes are fused to septa which extend up to half the length of the processes (Pl. 2, fig. 6). These septa connect all the processes in the complex (Text-fig. 3). Prominent septa connect together up to four processes in any one complex. In such groups the septa reach their maximum height at the middle processes of the group. Septa are also present on single processes giving the appearance of a strongly flared base. All processes are solid, broad and taper distally, terminating in a flared distal tip which is rarely bifurcate (Pl. 2, fig. 5) or trifurcate (Pl. 1, fig. 6). Trabeculae are sometimes present at the midpoint of some processes, connecting two or more together (Text-fig. 3 and Pl. 2, figs. 1, 3). Occasionally, these trabeculae are pronounced, extending up to eight times the width of the processes (Pl. 1, fig. 3). Some median trabeculae bear short distal processes which are unrelated to a proximal process. Where present, they do not exceed the ambitus of other processes (see Pl. 1, fig. 3). Trabeculae connecting the distal tips of the processes are not present.
Paratabulation is indicated by the archaeopyle suture and the process complexes. The formula derived is 4',6",3-6c,6"',1p, 1"" (in the notation of Evitt, 1985; A-C, 1-6, ?c-f, I-VI, X-Y). There is no apparent subdivision of the parasulcal area into component paraplates although the position of the parasulcus may be reflected by the bilobed antapical margin of the cyst (Pl. 1, fig. 3).
The operculum is Type tA (free) formed by the loss of paraplates 1' - 4". The archaeopyle suture is zig-zag with a prominent offset sulcal notch and notable accessory sutures.

Remarks:
There is considerable variation in the morphology of the process complexes, septa and trabeculae between specimens of this species (see Pls 1 and 2). The majority of processes are solid, ribbon-like and unbranched with part of each complex connected together by septa. Specimens with extensive developments of trabeculae at the midpoints of the processes are uncommon and may represent extreme variants. The operculum is rarely observed to be adherent to the cyst; where it is attached the principle archaeopyle parasuture is evident as a zig-zag split in the cyst wall separating the operculum from the rest of the cyst (Pl. 1, figs 4, 6). Process complexes on the ventral surface show some variability, especially in the 6" complex, which may be fragmentary linear, arcuate or soleate. In addition, the individual processes on the 6" paraplate may be reduced in length compared to other processes on the same specimen.
Remarks to occurrences:
Some previous palynological investigations of Thanetian sediments have also illustrated specimens attributed here to Areoligera gippingensis. As discussed above, the specimens illustrated by Gocht (1969) as A. senonensis are probably of A. gippingensis. Although Gocht indicates that the range of A. senonensis in his material was Palaeocene, Untereozan 1, 3, 4 and questionably Oligocene, it is possible that the unillustrated specimens recorded in Eocene and Oligocene sediments are attributable to another part of the A. senonesis complex of Eaton (1976). Schumacker - Lambry & Chateauneuf (1976) and Schumacker - Lambry (1978) illustrated the taxon from the Marnes de Gelinden, Heersian stratotype in Belgium as A. coronata (pl. 3, figs 3, 4; 1976), A. cf. coronata (pl. 1, fig. 5; 1978), A. senonensis (pl.3, fig.5; 1976) and possibly as Cyclonephelium ordinatum (pl. 3, fig. 13; 1978).
Similarly, Heilmann-Clausen (1985) recorded and illustrated specimens, which are thought to be attributable to A. gippingensis, as A. cf. senonensis (pl.,14, figs 4-7) and as A. cf. coronata (pl.14, fig. 3) from the Palaeocene of the Viborg 1 borehole, Denmark.

Affinities/Comparisons:
The study by Gocht (1969) illustrated several specimens as A. senonensis (text-figures 40, a, c-f, 41, a-c, pl. 8, figs 5-9 only) probably attributable to A. gippingensis from the Palaeocene of Germany. The illustrated specimens appear comparable in size, shape, morphology of processes and the distribution of annular, soleate and arcuate complexes on the ventral surface. The photographic illustrations of Gocht are not sufficiently clear to determine the accuracy of this attribution. However, the detailed camera-lucida drawings provided do not indicate the presence of dorsal paracingular processes in the north German material. The lack of these processes introduces an element of doubt to this comparison. Areoligera gippingesis is most closely similar to Areoligera senonensis Lejeune-Carpentier 1938, the holotype of which is contained in a flint chip and consequently not well illustrated. The line drawings of the holotype and other specimens by Lejeune-Carpentier (1938) show only the dorsal surface of A. senonensis which has annular complexes with up to fourteen processes on the precingular, postcingular and antapical paraplates. No cingular processes are indicated, all of the processes taper to an evexate or acuminate distal tip with processes of differing lengths occurring on the same complex. The ventral surface is not illustrated by either Lejeune-Carpentier (1938) or Lejeune-Carpentier & Sarjeant (1981). The description provided by Lejeune-Carpentier (1938: 164) suggests that the ornamentation of processes is absent or severely reduced on the mid ventral surface. The contention of Lejeune-Carpentier & Sarjeant (1981) that the morphology of A. senonensis is comparable to the specimens illustrated by Gocht (1969) as A. senonensis is not supported by comparison of the drawings of Gocht (text-figs 40, 41) with the only detailed illustration of the holotype (Lejeune-Carpentier, 1938, text-figs 1-3). In summary, A. gippingensis differs from A. senonensis in the possession of processes on the dorsal paracingular paraplates and the presence of process complexes on the ventral surface. In addition, the processes of A. gippingensis are distally flared to "t" -shaped terminations while those of A. senonensis are either evexate or acuminate. While the type material of A. senonensis remains unmeasured, a difference in size in comparison to A. gippingensis remains a possibility. Eaton (1976) proposed an Areoligera senonensis complex in which three basic taxa A. senonensis, A. medusettiformis and A. coronata (identified from the Eocene sediments of England) were grouped. Specimens which possessed ventral process complexes occurred in all three species and were distinguished from those without them by the use of cf. status. Subsequently, Morgenroth (1968) proposed that A. medusettiformis was a junior synonym of A. coronata, a synonymy accepted here. A. senonensis and A. cf. senonensis Lejeune-Carpentier 1938 sensu Eaton 1976 have weakly developed septa and thread-like slender processes with flared tips shorter than those of A. gippingensis. A. cf. senonensis sensu Williams & Downie 1966 is characterised by numerous thread-like trabeculae, more intricate in form than those in A. gippingensis. A. cf. coronata (O. Wetzel) Lejeune-Carpentier 1938, sensu Eaton 1976, can be distinguished from A. gippingensis by the thick distal trabeculae supporting numerous short spines. Species recorded from Eocene and Oligocene sediments such as A. semicirculata (Morgenroth) Stover & Evitt 1978 and A. undulata Eaton 1976 can be distinguished by the presence of broad membranous processes developed on the dorsal and ventral margins of the cyst. Species that have been described from Danian sediments such as A. crescentis Damassa 1979, A. volata Drugg, 1967 and A. tenuicapillata (O. Wetzel) Lejeune-Carpentier 1938 differ from A. gippingensis in the possession of shorter, slender processes which have more complex distal and medial trabeculae.

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Notes:
G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP VIEWER CD-ROM 99.5.

Areoligera gippingensis Jolley, 1992. Diagnosis from Jolley (1992, p.26). Large skolochorate dinoflagellate cysts, circular in outline, dorso-ventrally compressed, cyst wall of autophragm only. Processes grouped into penitabular complexes, parallel sided, straight (length ½ to 3/4 of body diameter), solid and ribbon-like, tapering distally before a flared tip. Complexes of processes composed of groups of up to twelve, connected by septa not exceeding ½ process length. Median trabeculae may exceed the processes by eight times and bear short distal processes, unrelated to a proximal process, distal trabeculae are not present. Soleate process complexes on 1", 2", 3", 4", 5", 1"’, 2"’, 3"’. 4"’. 5"’. Annular complexes on 1-4', 1"”, linear process complexes on dorsal cingulars and posterior intercalary. No complex on 6"’, arcuate to fragmentary complex on 6". Processes 15-33 µm. Jolly states that Areoligera cf. senonensis sensu Williams and Downie is characterized by numerous thread-like trabeculae, more intricate in form than those in A.gippingensis.
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