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Muderongia dedecosa
Original description Gocht, 1957 for Phoberocysta neocomica ssp. dedecosa:
Carapace with closed lateral margins, without lobes, and only angularly emarginate in places. Lateral horns broad-based, slightly downward-curved, and distinctly notched at the edge. Antachical horn weakly serrated; carapace completely smooth, without any trace of furrowing; only one halved specimen shows a transverse fold. Dimensions of the specimen in Fig. 11: length 91 µm, width 72 µm, apical horn 15 µm, antachical horn 17 µm, lateral horns approximately 12 µm each. Occurrence: One complete and two halved specimens in sample 9.
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emended description Duxbury, 2023
Plate 34, Figures 4, 5
Wetzeliella ? neocomica forma dedecosa GOCHT 1957, p. 177; text-fig. 11. Holotype: text-fig. 11
Wetzeliella ? neocomica forma circulata GOCHT 1957, p. 178; text-fig. 14
Phoberocysta neocomica subsp. dedecosa (Gocht 1957).– LENTIN and WILLIAMS 1973, p. 112.
Phoberocysta neocomica subsp. circulata (Gocht 1957, p. 178; text-fig. 14).– LENTIN and WILLIAMS 1973, p. 112.
Emended diagnosis: Asmooth to finely scabrate, proximate and circumcavate cyst with two wall layers clearly represented. Four horns are present, including a narrow apical and two equal laterals which are short, wide and clearly notched distally; short postcingular projections can occur on both lateral horns. A single, narrow antapical horn is centrally placed, lending bilateral symmetry to this species. Tabulation typical of the genus may be marked by low sutural lineations and by the apical archeopyle margin, a faint cingulum and a sometimes prominent sulcal notch. The endocyst is well-defined, rounded and without prominent projections. The baggy hypopericyst is often distorted and displays large, elongate lateral holes or splits which can run from the cingulum to two lateral bulges at the base of the antapical horn. The operculum is usually lost.
Remarks: Gocht (1957) described several “forma” of Wetzeliella ? neocomica - now Phoberocysta neocomica (Gocht 1957) Millioud 1969, including two, Wetzeliella ? neocomica forma dedecosa and Wetzeliella ? neocomica forma circulata, which lacked the spiny ornament of the others.
In transferring Gocht’s species to his new genus, Phoberocysta, Millioud (1969, p. 432) remarked that, “The general outline … is also very close to that of Muderongia, but the various described species of the latter genus all have a relatively smooth wall. It is therefore appropriate to create a new genus to accommodate the related, but heavily ornamented forms”. All of Gocht’s “forma” were incorporated into Phoberocysta neocomica by Millioud, including the two without spines, and this was further formalised by Lentin and Williams (1973) who listed them as subspecies of P. neocomica.
Gocht’s descriptions of P. neocomica subsp. dedecosa and P. neocomica subsp. circulata were very similar and are reflected in the emended diagnosis above. His separation of the two was essentially based on the former lacking sutures whereas the latter had them; this difference was illustrated in his text-figures 11 and 14. In the present study, otherwise very similar examples with and without clear sutures have been recorded and both of Gocht’s spine-free “formas” have therefore been combined and raised to species rank here.
Muderongia dedecosa is superficially similar to some specimens of Muderongia simplex Alberti 1961, illustrated in Duxbury 2018 (Pl. 15, Figs. 14, 15 and text-fig. 5, Figs. 14, 15) but it differs in being much larger and in possessing lateral holes/slits in the hypopericyst. The average size of the two specimens of M. simplex mentioned above is breadth 70 μm and length 72 μm, whereas the size range of M. dedecosa here is breadth 104(93)81 μm and length 109(94)81 μm; 10 specimens were measured, all with the operculum lost. Muderongia dedecosa is very similar to a specimen from the early Hauterivian, illustrated as M. australis Helby 1987 by Prössl (1990, Pl. 2, Fig. 8), including a “baggy” hypopericyst with lateral holes/splits. Prössl’s specimen differs slightly, however, in having rare spines.
Carapace with closed lateral margins, without lobes, and only angularly emarginate in places. Lateral horns broad-based, slightly downward-curved, and distinctly notched at the edge. Antachical horn weakly serrated; carapace completely smooth, without any trace of furrowing; only one halved specimen shows a transverse fold. Dimensions of the specimen in Fig. 11: length 91 µm, width 72 µm, apical horn 15 µm, antachical horn 17 µm, lateral horns approximately 12 µm each. Occurrence: One complete and two halved specimens in sample 9.
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emended description Duxbury, 2023
Plate 34, Figures 4, 5
Wetzeliella ? neocomica forma dedecosa GOCHT 1957, p. 177; text-fig. 11. Holotype: text-fig. 11
Wetzeliella ? neocomica forma circulata GOCHT 1957, p. 178; text-fig. 14
Phoberocysta neocomica subsp. dedecosa (Gocht 1957).– LENTIN and WILLIAMS 1973, p. 112.
Phoberocysta neocomica subsp. circulata (Gocht 1957, p. 178; text-fig. 14).– LENTIN and WILLIAMS 1973, p. 112.
Emended diagnosis: Asmooth to finely scabrate, proximate and circumcavate cyst with two wall layers clearly represented. Four horns are present, including a narrow apical and two equal laterals which are short, wide and clearly notched distally; short postcingular projections can occur on both lateral horns. A single, narrow antapical horn is centrally placed, lending bilateral symmetry to this species. Tabulation typical of the genus may be marked by low sutural lineations and by the apical archeopyle margin, a faint cingulum and a sometimes prominent sulcal notch. The endocyst is well-defined, rounded and without prominent projections. The baggy hypopericyst is often distorted and displays large, elongate lateral holes or splits which can run from the cingulum to two lateral bulges at the base of the antapical horn. The operculum is usually lost.
Remarks: Gocht (1957) described several “forma” of Wetzeliella ? neocomica - now Phoberocysta neocomica (Gocht 1957) Millioud 1969, including two, Wetzeliella ? neocomica forma dedecosa and Wetzeliella ? neocomica forma circulata, which lacked the spiny ornament of the others.
In transferring Gocht’s species to his new genus, Phoberocysta, Millioud (1969, p. 432) remarked that, “The general outline … is also very close to that of Muderongia, but the various described species of the latter genus all have a relatively smooth wall. It is therefore appropriate to create a new genus to accommodate the related, but heavily ornamented forms”. All of Gocht’s “forma” were incorporated into Phoberocysta neocomica by Millioud, including the two without spines, and this was further formalised by Lentin and Williams (1973) who listed them as subspecies of P. neocomica.
Gocht’s descriptions of P. neocomica subsp. dedecosa and P. neocomica subsp. circulata were very similar and are reflected in the emended diagnosis above. His separation of the two was essentially based on the former lacking sutures whereas the latter had them; this difference was illustrated in his text-figures 11 and 14. In the present study, otherwise very similar examples with and without clear sutures have been recorded and both of Gocht’s spine-free “formas” have therefore been combined and raised to species rank here.
Muderongia dedecosa is superficially similar to some specimens of Muderongia simplex Alberti 1961, illustrated in Duxbury 2018 (Pl. 15, Figs. 14, 15 and text-fig. 5, Figs. 14, 15) but it differs in being much larger and in possessing lateral holes/slits in the hypopericyst. The average size of the two specimens of M. simplex mentioned above is breadth 70 μm and length 72 μm, whereas the size range of M. dedecosa here is breadth 104(93)81 μm and length 109(94)81 μm; 10 specimens were measured, all with the operculum lost. Muderongia dedecosa is very similar to a specimen from the early Hauterivian, illustrated as M. australis Helby 1987 by Prössl (1990, Pl. 2, Fig. 8), including a “baggy” hypopericyst with lateral holes/splits. Prössl’s specimen differs slightly, however, in having rare spines.