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Surculosphaeridium cribrotubiferum ssp. cribrotubiferum

Surculosphaeridium cribrotubiferum ssp. cribrotubiferum

Autonym.
Holotype: Sarjeant, 1960, pl.6, fig.2; Stancliffe and Sarjeant, 1990, text-fig.3, nos.4,6
Locus typicus: Furzy Cliff, Weymouth, Oxford Clay
Stratum typicum: Cordatum Zone, Early Oxfordian

Original diagnosis: Sarjeant, 1960, p. 137: Hystrichosphaeridium cribrotubiferum
A species of Hystrichosphaeridium having a spheroidal shell bearing a moderate number (less than forty) of tubular appendages of variable thickness, arising from broadened bases. The bases sometimes have root-like extensions. The open ends of the appendages give rise to fibrils of very variable length, number and direction: these fibrils sometimes bifurcate. The walls of the tubes are perforate, the perforations being of very constant diameter and distance apart in any particular tube and arranged in rows along the tube"s length. Adjacent perforations in different rows show an arrangement in quincunx in relation to one another.

Original description: Sarjeant, 1960, p. 137: Hystrichosphaeridium cribrotubiferum
The shell is yellowish in colour and devoid of surface ornament. All specimens seen were in some degree obscured by extraneous organic material caught up by their processes. Dimensions. Type: overall diameter 75 µm, shell diameter 46 µm, processes c. 16 µm long and 1.5 to 3.5 µm broad. The range of overall diameters observed was from 60 to 80 µm.

Emended diagnosis: Davey et al., 1960, p. 161
Subsphaerical central body bearing moderate number of solid distally closed, perforate processes. Processes variably branched, sometimes deeply, especially cingular processes. Processes reflect a tabulation of 6", 6"", 6c, 6""", 1p, 3"""".

Emended diagnosis: Stancliffe and Sarjeant, 1990, p.207
Body subspherical, skolochorate, without crests. Phragma composed of two layers. Intratabular processes reflect the tabulation formula 4", 6", 6c, 6""", 1p, 3"""", ?1s. Processes large, thick, solid, and distally closed. Proximally the main processes have striations on their walls, extending onto the surface of the phragma. Processes may develop first and second order branching. Process walls typically exhibit circular depressions between the striations: these are of variable size and depth, with steep sides. The cingulum is marked bv six thin processes, which may be deeply bifurcate; the sulcus may be devoid of processes or may bear a single thin, solid process. The apical archeopyle, type (tA), has short accessory archeopyle sutures and a deep sulcal notch.

Affinities:
Sarjeant, 1960, p. 138: Hystrichosphaeridium cribrotubiferum
The possession of perforations in the tubes, a feature observable only at higher magnification, distinguishes them from all known species of Hystrichosphaeridium. Of existing species, the most closely comparable, is H. salpingophorum (Deflandre) also present at this horizon: this latter species also differs in that fibrils at the tube mouth extend as raised striations down the walls of the tube and out onto the tube surface as rootlets, whereas the tubes of H. cribrotubiferum Iack striations.
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