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Hystrichokolpoma crassipes

Hystrichokolpoma crassipes (Reade, 1839) emend. Lejeune-Carpentier and Sarjeant, 1981

Originally Xanthidium, subsequently Hystrichosphaeridium, thirdly Litosphaeridium?, fourthly (and now) Hystrichokolpoma.
Tax. sr. synonym of Pervosphaeridium truncigerum (Deflandre, 1937) Yun, 1981, by implication, according to Yun, 1981, who considered Pervosphaeridium truncigerum to be the sr. synonym. Lentin and Williams, 1985, retained Pervosphaeridium truncigerum as a separate species.
Holotype: Reade, 1839, pl.9, fig.2 (lost, according to Lejeune-Carpentier and Sarjeant, 1981)
Neotype: Lejeune-Carpentier, 1941, fig.9; Lejeune-Carpentier and Sarjeant, 1981, pl.3, fig.3; text-fig.6 (designated by Lejeune-Carpentier and Sarjeant, 1981)
Age: Late Cretaceous

Reade, 1839:
No description in this article. Xanthidium crassipes is sketched here.

Emended diagnosis: Lejeune-Carpentier and Sarjeant 1981, p. 10-12
Cyst spheroidal to braodly ovoidal, the apex lost in archeopyle formation. Intratabular processes of three types developed: 1. Large processes, broad-based and tapering slightly towards their tips, closed proximally but open distally. These processes correspond in position to precingular, postcingular and antapical paraplates. 2. Smaller, spine-like processes, acuminate or oblate, closed or open proximally but consistently closed distally. These processes correspond in situation to cingulum and sulcus (and possibly to a second posterior intercalary plate). 3. A single broad, flat, blade-like process, closed distally and proximally, corresponds in situation to the posterior plate.
The antapical process is the longest, exceeding in length one-quarter of the cyst breadth. The length of all the other processes is less than one-quarter of the cyst breadth. The processes reflect a paratabulation as follows: ?", Oa, 6", 6 or 7c, 5 or 6"", 1-?2p, I pv, 1"", 9-?l ls. Rootlike ridges radiate out across the surface of the phragma from the bases of the larger processes and faint lines between adjacent processes, simulating paraplates, mark the limits of extension of these ridges. The phragma also exhibits a coarse granulation or punctation.

Neotype: Lejeune-Carpentier 1941: fig.9 and Lejeune-Carpentier and Sarjeant 1981: pl.3: 3, Text-fig. 6.
Type Horizon and Locality (of Neotype): Flint of Craie de Spiennes (= Formatie van Gulpen of Felder,1975), Upper Cretaceous, (Senonian), Mortiau quarry, Cuesmes, Belgium.

Description: Lejeune-Carpentier and Sarjeant 1981, p. 10-12
The neotype is seen in slightly oblique ventral view, so that the ventral and right lateral surfaces are well shown; the morphology of the dorsal and left lateral surfaces is less easy to determine. Orientation is imposed on the basis (a.) of the archaeopyle, certainly essentially apical; (b.) of an unusually large single process, here considered antapical in situation and (c.) of the single line of smaller processes separating the larger ones on both surfaces, considered to be cingular processes. On this basis, a striking feature of this specimen (and species) is the high number of sulcal processes: at least nine are present, perhaps eleven if the supposed seventh cingular and second posterior intercalary processes (see Text-fig. 6) are also sulcals. The faint lines separating the convergences of rootlike extensions from adjacent processes may delimit paraplates; but if so, the cingulum is not directly indicated and the limits of the sulcus are obscure.

Dimensions: Neotype: length of cyst 38Ám, breadth 46Ám, length of antapical process 13Ám, maximum length of other processes c.10Ám.

Remarks: Lejeune-Carpentier and Sarjeant 1981, p. 10-12
This species was first illustrated, without description, by Reade (1839): despite prolonged enquiry by the second author in British museums and collections, the holotype has not come to light and must be presumed lost. The specimens attributed to this species by White (1842, 1844) differ too substantially in the morphology and proportionate length of their processes to be regarded nowadays as attributable even to the same genus, let alone to the same species; in any case, they too are lost. Moreover, the locality and stratigraphical horizon of Reade"s specimens were not precisely stated, precluding the collection of new material from the same position. In consequence, the specimen described and illustrated earlier by one of us (Lejeune- Carpentier, 1941) is here selected as neotype and the revised diagnosis is based on that specimen. The archeopyle is certainly essentially apical, though it may also involve a dorsal precingular paraplate; the position of the neotype in the enclosing flint precluded confidence in this regard. Despite this uncertainty, the presence of processes of three distinct types, including cingular processes and a high number of sulcal processes, sufficently facilitates the identification of this species as to fully justify its retention. Its generic placement must, however, be regarded as provisional. It is certainly not attributable to Litosphaeridium, which has fewer processes (16-19) and lacks cingulars and sulcals. Though similar in many respects, Achilleodinium has a precingular archaeopyle only. The archaeopyles of Florentinia and Silicisphaera likewise consistently involve (and may be entirely formed by) loss of a precingular paraplate; however, the apical paraplates may also be lost. Placement in Silicisphaera is clearly inappropriate, since that genus lacks a distinctive antapical process and has equatorial (precingular and postcingular) processes with transversely elongate bases. Provisional attribution to Hystrichokolpoma is made on the basis that the archaeopyle appears exclusively apical; if it proves otherwise, then reallocation to Florentinia may become appropriate. However, it should be noted that, in the typical species of both latter genera, the number of sulcals does not exceed five, so that placement of the species crassipes into a genus yet unnamed may well ultimately prove necessary.
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