160
F.]. R. TAYLOR:
Material from the "Anton Bruun" collections was used to supplement the description
of a new genus Discroerisma (TAYLOR and CATTELL, 1969) and a further new genus
related to Ptychodiscus will be described in the monograph in preparation.
Fig. 4. a Ceratium trichoceros. b Ceratium massi/iense var. macroceroides. c Ceratocorys horrida.
The individual illustrated is a relatively long-spined form. d Pyrocystis pseudonoctiluca. e Histioneis
mitchel/ana, a representative of the structurally complex dinophysoid species restricted to the
tropics and considered a "shade species". f Ceratium gravidum, a common member of the subgenus
Archaeceratium, exhibiting the broad, flattened epitheca found only within the group. This specimen
illustrates the most elongate form of the species, others having an almost circular epitheca. g Citharistes apsteinii, one of the only two species of this rare dinophysoid genus, illustrating the greatly
enclosed, girdle-derived "phaeosome chamber" thought to usually, but not invariably, contain
blue-green algal symbionts (dotted outlines). Numbers beside scale lines indicate the length
represented, in microns