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Selenopemphix brevispinosa
Selenopemphix brevispinosa Head et al., 1989
Holotype: Head et al., 1989, pl.7, fig.5
Locus typicus:Baffin Bay, N Atlantic
Stratum typicum: Middle or early late? Miocene
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP
Selenopemphix brevispinosa Head et al., 1989b. According to Head et al. (1989c, p.494), Selenopemphix brevispinosa has a smooth to faintly granulate body and parasutural ornament restricted to the paracingular margins and consisting of short distally expanded processes. The archeopyle formed by the loss of intercalary paraplate 2a is large and offset.The processes are always distally expanded with truncated tips. They are usually slender for most of their length, although on specimens having short processes, the process stems can be wide (1 µm or more). This species differs from S.coronata in having shorter processes that are less closely spaced and that are always distally separated. Processes on S.brevispinosa are short and evenly distributed along the paracingular margins, compared with those on S.dionaeacysta, which are both longer (4-8 µm) and may have a loosely clustered distribution along the paracingular margins. Size: maximum body diameter excluding processes 36-48 µm, processes 1.2-3.2 µm.
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Original diagnosis Head et al., 1989, p.494:
A species of Selenopemphix having smooth to faintly granulate body and parasutural ornament restricted to the paracingular margins and consisting of short distally expanded processes. The archeopyle formed by loss of intercalary paraplate 2a and is large and offset.
Original description Head et al., 1989, p.494:
Processes are always distally expanded with truncated tips. They are usually slender for most of their length (as on the holotype), although on specimens having short processes, the process stems can be wide (1 µm or more).
Dimensions. Holotype: maximum body diameter (excluding processes), 46µm; process, 3.0 µm long. Range in maximum body diameter (excluding processes), 36 (41.8) 48 µm; processes from 1.2 to 3.2 µm long. Twenty specimens were measured.
Comparisons:
Head et al., 1989, p.494:
This species differs from S. coronata Bujak, 1980 in having shorter processes that are less closely spaced and that are always distally separated. Processes on S. brevispinosa are short and evenly distributed along the paracingular margins, compared with those on S. dionaeacysta Head et al., 1989 which are both longer (4-8 µm) and may have a loosely clustered distribution along the paracingular margins. This species has been recorded from the Gulf of Mexico, where it may be restricted to mid-Miocene sediments (as Selenopemphix sp. C in Duffield and Stein, 1986); and from the lowermost Pliocene of Italy (as "Selenopemphix sp. C Duffield and Stein, 1986" in Corradini and Biffi, 1988). Selenopemphix sp. A of Brown and Downie, 1985, from the late Miocene of the Goban Spur, and Selenopemphix sp. B of Powell, 1986 (considered by him as synonymous with Selenopemphix sp. A of Brown and Downie, 1985) from the late Miocene of northern Italy may be synonymous with S. brevispinosa, although details of their processes are difficult to determine from the illustrations.
Holotype: Head et al., 1989, pl.7, fig.5
Locus typicus:Baffin Bay, N Atlantic
Stratum typicum: Middle or early late? Miocene
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G.L. Williams short notes on species, Mesozoic-Cenozoic dinocyst course, Urbino, Italy, May 17-22, 1999 - LPP
Selenopemphix brevispinosa Head et al., 1989b. According to Head et al. (1989c, p.494), Selenopemphix brevispinosa has a smooth to faintly granulate body and parasutural ornament restricted to the paracingular margins and consisting of short distally expanded processes. The archeopyle formed by the loss of intercalary paraplate 2a is large and offset.The processes are always distally expanded with truncated tips. They are usually slender for most of their length, although on specimens having short processes, the process stems can be wide (1 µm or more). This species differs from S.coronata in having shorter processes that are less closely spaced and that are always distally separated. Processes on S.brevispinosa are short and evenly distributed along the paracingular margins, compared with those on S.dionaeacysta, which are both longer (4-8 µm) and may have a loosely clustered distribution along the paracingular margins. Size: maximum body diameter excluding processes 36-48 µm, processes 1.2-3.2 µm.
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Original diagnosis Head et al., 1989, p.494:
A species of Selenopemphix having smooth to faintly granulate body and parasutural ornament restricted to the paracingular margins and consisting of short distally expanded processes. The archeopyle formed by loss of intercalary paraplate 2a and is large and offset.
Original description Head et al., 1989, p.494:
Processes are always distally expanded with truncated tips. They are usually slender for most of their length (as on the holotype), although on specimens having short processes, the process stems can be wide (1 µm or more).
Dimensions. Holotype: maximum body diameter (excluding processes), 46µm; process, 3.0 µm long. Range in maximum body diameter (excluding processes), 36 (41.8) 48 µm; processes from 1.2 to 3.2 µm long. Twenty specimens were measured.
Comparisons:
Head et al., 1989, p.494:
This species differs from S. coronata Bujak, 1980 in having shorter processes that are less closely spaced and that are always distally separated. Processes on S. brevispinosa are short and evenly distributed along the paracingular margins, compared with those on S. dionaeacysta Head et al., 1989 which are both longer (4-8 µm) and may have a loosely clustered distribution along the paracingular margins. This species has been recorded from the Gulf of Mexico, where it may be restricted to mid-Miocene sediments (as Selenopemphix sp. C in Duffield and Stein, 1986); and from the lowermost Pliocene of Italy (as "Selenopemphix sp. C Duffield and Stein, 1986" in Corradini and Biffi, 1988). Selenopemphix sp. A of Brown and Downie, 1985, from the late Miocene of the Goban Spur, and Selenopemphix sp. B of Powell, 1986 (considered by him as synonymous with Selenopemphix sp. A of Brown and Downie, 1985) from the late Miocene of northern Italy may be synonymous with S. brevispinosa, although details of their processes are difficult to determine from the illustrations.