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Selenopemphix porcupensis
Selenopemphix porcupensis Louwye et al., 2008, p.136,138, pl.3, figs.1–9.
Holotype: Louwye et al., 2008, pl.3, figs.1–5.
Age: late Burdigalian–Langhian.
Original description (Louwye et al., 2008)
Holotype. Plate 3, figs. 1–5. Slide 36-P1, sample U1318B-19X-2, 33–35 cm, 169.0 mbsf. England Finder reference K18/3. IRSNB catalogue number b5106. Locality: Porcupine Basin, offshore southwest Ireland. Age: Middle Miocene (Chron C5ADn, Langhian).
Etymology. Named after the Porcupine Basin, where the IODP Expedition 307 drill sites are located.
Diagnosis. Large, polar compressed, acavate, brown colored cyst with poorly-developed apical and antapical horns. Autophragm sparsely ornamented with discrete granules and striae radiating from the poles toward the cingulum. Cingulum is characterized by two parallel, discontinuous rows of short, irregular bulbous or capitate processes. Archeopyle is formed by the release of a single anterior intercalary plate. Free operculum, occasionally adherent.
Description. The single-layered cyst has a strong polar compression, and a subcircular to subreniform outline in polar view. One apical and two antapical horns are weakly developed. The autophragm is dark to medium brown and thin (< 0.3 μm). The surface ornamentation is scabrate to shagreenate. It consists of small granule-like projections with a maximum height of <1 μm, and linear striae running from the polar areas toward the cingulum. The width of the striae are approximately 1.5 μm; they do not cross or interconnect. The margins of the cingulum form two distinct rims or ridges, each carrying a row of small solid processes. The processes are closely-spaced, and their bases are slightly expanded or straight. The maximum length of the processes is 3 μm, and the width of the process stem does not exceed 1.5 μm. The processes weakly expand distally, and the terminations are irregularly bulbous or capitate. A few processes may be distally bifurcate and connect to neighboring processes. The processes are absent over a short distance (approximately 15 μm) left and right of the sulcal area (Plate 3, fig. 1). The sulcal area is indicated by a pronounced indentation. The archeopyle is formed by the release of plate 2a, and is iso-deltaform. The position of the archeopyle is distinctly offset to the left of the dorsoventral midline. The free operculum may remain attached along part of the suture. No accessory archeopyle sutures are present.
Dimensions. Holotype: maximum dimension between lateral sides in polar view: 92 μm; minimum dimension between dorsal and ventral side in polar view: 82 μm. Range: maximum dimension between lateral sides in polar view: 82(92)105 μm; minimum dimension between dorsal and ventral side in polar view: 74(86)96 μm. Number of specimens measured: 5.
Comparison. Selenopemphix porcupensis sp. nov. is easily recognized by its large size compared to other species of Selenopemphix (Plate 3, fig. 9). The size of Selenopemphix antarctica Marret & de Vernal 1997 is comparable to the size of Selenopemphix porcupensis sp. nov., but the autophragm and cingulum are unornamented. Selenopemphix crenata Matsuoka and Bujak 1980 is much smaller (34–76 μm), and has a cingular ornamentation consisting of two deeply crenulated or serrated ridges. Selenopemphix coronata Bujak in Bujak et al. 1980 has solid, slender, and bifurcating spines 3.5–5.0 μm long in the cingular area, which have bulbous terminations or are connected to the neighboring spine.
Occurrence. The only record of this species is from the Miocene of the Porcupine Basin (Louwye et al., 2007). The species occurs from the upper Burdigalian to the Langhian, and is absent in the Serravallian .Selenopemphixporcupensis sp. nov. is never abundant, and was only recorded outside the systematic count of 300 specimens (Text-Figure 3).
Holotype: Louwye et al., 2008, pl.3, figs.1–5.
Age: late Burdigalian–Langhian.
Original description (Louwye et al., 2008)
Holotype. Plate 3, figs. 1–5. Slide 36-P1, sample U1318B-19X-2, 33–35 cm, 169.0 mbsf. England Finder reference K18/3. IRSNB catalogue number b5106. Locality: Porcupine Basin, offshore southwest Ireland. Age: Middle Miocene (Chron C5ADn, Langhian).
Etymology. Named after the Porcupine Basin, where the IODP Expedition 307 drill sites are located.
Diagnosis. Large, polar compressed, acavate, brown colored cyst with poorly-developed apical and antapical horns. Autophragm sparsely ornamented with discrete granules and striae radiating from the poles toward the cingulum. Cingulum is characterized by two parallel, discontinuous rows of short, irregular bulbous or capitate processes. Archeopyle is formed by the release of a single anterior intercalary plate. Free operculum, occasionally adherent.
Description. The single-layered cyst has a strong polar compression, and a subcircular to subreniform outline in polar view. One apical and two antapical horns are weakly developed. The autophragm is dark to medium brown and thin (< 0.3 μm). The surface ornamentation is scabrate to shagreenate. It consists of small granule-like projections with a maximum height of <1 μm, and linear striae running from the polar areas toward the cingulum. The width of the striae are approximately 1.5 μm; they do not cross or interconnect. The margins of the cingulum form two distinct rims or ridges, each carrying a row of small solid processes. The processes are closely-spaced, and their bases are slightly expanded or straight. The maximum length of the processes is 3 μm, and the width of the process stem does not exceed 1.5 μm. The processes weakly expand distally, and the terminations are irregularly bulbous or capitate. A few processes may be distally bifurcate and connect to neighboring processes. The processes are absent over a short distance (approximately 15 μm) left and right of the sulcal area (Plate 3, fig. 1). The sulcal area is indicated by a pronounced indentation. The archeopyle is formed by the release of plate 2a, and is iso-deltaform. The position of the archeopyle is distinctly offset to the left of the dorsoventral midline. The free operculum may remain attached along part of the suture. No accessory archeopyle sutures are present.
Dimensions. Holotype: maximum dimension between lateral sides in polar view: 92 μm; minimum dimension between dorsal and ventral side in polar view: 82 μm. Range: maximum dimension between lateral sides in polar view: 82(92)105 μm; minimum dimension between dorsal and ventral side in polar view: 74(86)96 μm. Number of specimens measured: 5.
Comparison. Selenopemphix porcupensis sp. nov. is easily recognized by its large size compared to other species of Selenopemphix (Plate 3, fig. 9). The size of Selenopemphix antarctica Marret & de Vernal 1997 is comparable to the size of Selenopemphix porcupensis sp. nov., but the autophragm and cingulum are unornamented. Selenopemphix crenata Matsuoka and Bujak 1980 is much smaller (34–76 μm), and has a cingular ornamentation consisting of two deeply crenulated or serrated ridges. Selenopemphix coronata Bujak in Bujak et al. 1980 has solid, slender, and bifurcating spines 3.5–5.0 μm long in the cingular area, which have bulbous terminations or are connected to the neighboring spine.
Occurrence. The only record of this species is from the Miocene of the Porcupine Basin (Louwye et al., 2007). The species occurs from the upper Burdigalian to the Langhian, and is absent in the Serravallian .Selenopemphixporcupensis sp. nov. is never abundant, and was only recorded outside the systematic count of 300 specimens (Text-Figure 3).