Oligosphaeridium vasiformum (Neale and Sarjeant, 1962, p.452, pl.20, fig.1; text-fig.8b) Davey and Williams, 1966b, p.74–75. Holotype: Neale and Sarjeant, 1962, pl.20, fig.1; text-fig.8b; Fauconnier and Masure, 2004, pl.62, fig.4. Originally Hystrichosphaeridium, subsequently (and now) Oligosphaeridium. Taxonomic senior synonym: Hystrichosphaeridium (as Oligosphaeridium?) asterigerum, according to Duxbury (1977, p.45) — however, McIntyre and Brideaux (1980, p.21) retained Hystrichosphaeridium (as Oligosphaeridium) vasiformum. Taxonomic junior synonym: Hystrichosphaeridium (as Oligosphaeridium?) macrotubulum, according to McIntyre and Brideaux (1980, p.21). Age: middle Hauterivian–early Barremian.

Original diagnosis: Neale and Sarjeant, 1962, p.452: Hystrichosphaeridium vasiformum
A species of Hystrichosphaeridium having an oval shell of which one pole (apical) is frequently lost in pylome formation. The shell is densely perforate, the perforations being circular and of constant size. The tubes arise from root-like bases and are open distally; they taper initially but broaden again distally. At their extremities they give rise to 4-6 spines (most often 5) which are directed parallel to the shell surface and have a stellate arrangement round the tube mouth. The length of the tubes approximately equals the shortest shell diameter.

Original description: Neale and Sarjeant, 1962, p. 452: Hystrichosphaeridium vasiformum
Shell yellowish-brown, tubes paler. The tubes do not appear to connect with the shell interior. Their distal outgrowths have the form of spines of very variable length. The tubes often show a hollow just above their base; they are in no case perforate. 15-20 tubes present (without apical end).
Dimensions: Holotype; overall length 107.5 µm, breadth 116 µm, shell length 46.5 µm (apex lacking), breadth 52 µm. Range: Overall lengths 110-130 µm.