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Prolixosphaeridium prolatum
Plate 12, Figures 14-16
Prolixosphaeridium sp. A. MONTEIL 1993, pl. 1, fig. 6. – LEEREVELD 1997a, fig. 7g.
Prolixosphaeridium deirense Davey et al. 1966. – HARDING 1990, pl. 29, figs. 5, 6 only.
Holotype: Plate 12, Figure 16.
Type Locality: Vergol outcrop, late Berriasian, Bed B131M, alpillensis ammonite Zone, otopeta Sub-zone. Holotype: Slide B131(R1), E.F. Q42.2.
Derivation of Name: From the Latin prolatus, extended, elongated- in reference to the unusual length of this species.
Diagnosis: A fairly large, elongate-ellipsoidal species with the main body between 2 and 3 times as long as broad. The poles are rounded with the apical pole notably broader than the antapical. A fine, granular ornament covers the cyst surface and numerous (>60) slender, acuminate processes are present, typically approximating to half the main body width or less. Process length is usually consistent on individual specimens. The presumed tetratabular apical archeopyle is relatively small and the operculum often remains attached.
Dimensions: Holotype Main body 89 × 35 μm. Overall - 99 × 58 μm.
All specimens - Main body 104 (90) 78 μm × 43 (38) 35 μm.
Overall 111 (99) 86 μm × 71 (59) 51 μm.
Specimens measured: 8 (3 complete and 5 with the operculum detached).
Remarks: This is a large species compared to others of the genus, very elongate with numerous slender processes and it is restricted here to individuals with distally acuminate terminations ; the process length is typically half of the body width or less. On this basis, the specimen illustrated by Monteil (1993, pl. 1, fig. 6) is somewhat atypical but is nevertheless assigned to P. prolatum here. Prolixosphaeridium prolatum n. sp. resembles P. deirense Davey et al. 1966 emend Harding 1990 but is more elongate with shorter processes. Harding (op. cit., pl. 29, fig included in P. deirense a Tethyan specimen from Angles, "more elongate and with shorter processes" (Harding op. cit., pl. 29, figs. 5, 6); this is included in Prolixosphaeridium prolatum here. Prolixosphaeridium prolatum is also superficially similar to Prolixosphaeridium? foratum Dodekova 1994 but differs in being significantly longer (the main body length of P.? foratum ranges only between 60 μm and 79 μm as opposed to the 78 μm to 104 μm range of P. prolatum). Also, Dodekova (1994, p. 27) suggests that the surface of the autophragm in P.? foratum, "is rather scabrate than granulate", again contrasting with the finely granular surface of P. prolatum.
Very common to abundant Prolixosphaeridium prolatum were recorded between Beds B97M and B138M (late Berriasian, alpillensis Zone, alpillensis Sub-zone to early Valanginian, pertransiens Zone, premolicus Sub-zone), so that this appears to be a characteristic species as high as the basal Valanginian. The FO of P. prolatum is uncertain. Monteil's (1992b, Table 1) range for "Prolixosphaeridium sp. A" suggests a possible range at least as old as the Tithonian.
At Vergol, a major reduction in numbers of P. prolatum was observed above Bed B138M although consistent but relatively rare occurrences were recorded between Beds B142M and V42M (pertransiens to basal neocomiensiformis Zones). Monteil (1992b, Table 1) recorded this species to the top of the pertransiens Zone in southeast France and Leereveld (1997a, figs. 2, 3) recorded it up to a similar level in Spain.
The FO of a form similar to P. prolatum, Tanyosphaeridium hirsutum Duxbury n. sp., was in Bed B121M. Although similar, T. hirsutum tends to be somewhat smaller than P. prolatum and the processes, still numerous and still slender, are longer and distally open. Tanyosphaeridium hirsutum was common as old as Bed B151M (pertransiens Zone, premolicus Sub-zone) and ranged up to Bed V111 (late Valanginian, verrucosum Zone, base verrucosum Sub-zone).
The possible transition from P. prolatum to Tanyosphaeridium hirsutum close to the Berriasian/Valanginian boundary supports Harding's (1990, p. 47) suggestion that "these genera appear closely related".
Prolixosphaeridium sp. A. MONTEIL 1993, pl. 1, fig. 6. – LEEREVELD 1997a, fig. 7g.
Prolixosphaeridium deirense Davey et al. 1966. – HARDING 1990, pl. 29, figs. 5, 6 only.
Holotype: Plate 12, Figure 16.
Type Locality: Vergol outcrop, late Berriasian, Bed B131M, alpillensis ammonite Zone, otopeta Sub-zone. Holotype: Slide B131(R1), E.F. Q42.2.
Derivation of Name: From the Latin prolatus, extended, elongated- in reference to the unusual length of this species.
Diagnosis: A fairly large, elongate-ellipsoidal species with the main body between 2 and 3 times as long as broad. The poles are rounded with the apical pole notably broader than the antapical. A fine, granular ornament covers the cyst surface and numerous (>60) slender, acuminate processes are present, typically approximating to half the main body width or less. Process length is usually consistent on individual specimens. The presumed tetratabular apical archeopyle is relatively small and the operculum often remains attached.
Dimensions: Holotype Main body 89 × 35 μm. Overall - 99 × 58 μm.
All specimens - Main body 104 (90) 78 μm × 43 (38) 35 μm.
Overall 111 (99) 86 μm × 71 (59) 51 μm.
Specimens measured: 8 (3 complete and 5 with the operculum detached).
Remarks: This is a large species compared to others of the genus, very elongate with numerous slender processes and it is restricted here to individuals with distally acuminate terminations ; the process length is typically half of the body width or less. On this basis, the specimen illustrated by Monteil (1993, pl. 1, fig. 6) is somewhat atypical but is nevertheless assigned to P. prolatum here. Prolixosphaeridium prolatum n. sp. resembles P. deirense Davey et al. 1966 emend Harding 1990 but is more elongate with shorter processes. Harding (op. cit., pl. 29, fig included in P. deirense a Tethyan specimen from Angles, "more elongate and with shorter processes" (Harding op. cit., pl. 29, figs. 5, 6); this is included in Prolixosphaeridium prolatum here. Prolixosphaeridium prolatum is also superficially similar to Prolixosphaeridium? foratum Dodekova 1994 but differs in being significantly longer (the main body length of P.? foratum ranges only between 60 μm and 79 μm as opposed to the 78 μm to 104 μm range of P. prolatum). Also, Dodekova (1994, p. 27) suggests that the surface of the autophragm in P.? foratum, "is rather scabrate than granulate", again contrasting with the finely granular surface of P. prolatum.
Very common to abundant Prolixosphaeridium prolatum were recorded between Beds B97M and B138M (late Berriasian, alpillensis Zone, alpillensis Sub-zone to early Valanginian, pertransiens Zone, premolicus Sub-zone), so that this appears to be a characteristic species as high as the basal Valanginian. The FO of P. prolatum is uncertain. Monteil's (1992b, Table 1) range for "Prolixosphaeridium sp. A" suggests a possible range at least as old as the Tithonian.
At Vergol, a major reduction in numbers of P. prolatum was observed above Bed B138M although consistent but relatively rare occurrences were recorded between Beds B142M and V42M (pertransiens to basal neocomiensiformis Zones). Monteil (1992b, Table 1) recorded this species to the top of the pertransiens Zone in southeast France and Leereveld (1997a, figs. 2, 3) recorded it up to a similar level in Spain.
The FO of a form similar to P. prolatum, Tanyosphaeridium hirsutum Duxbury n. sp., was in Bed B121M. Although similar, T. hirsutum tends to be somewhat smaller than P. prolatum and the processes, still numerous and still slender, are longer and distally open. Tanyosphaeridium hirsutum was common as old as Bed B151M (pertransiens Zone, premolicus Sub-zone) and ranged up to Bed V111 (late Valanginian, verrucosum Zone, base verrucosum Sub-zone).
The possible transition from P. prolatum to Tanyosphaeridium hirsutum close to the Berriasian/Valanginian boundary supports Harding's (1990, p. 47) suggestion that "these genera appear closely related".