Mallomonas costata Dürrschmidt

Kapustin, Dmitry A., Gusev, Evgeniy S., Lilitskaya, Galina G. & Kulikovskiy, Maxim S., 2020, Silica-scaled chrysophytes from the Ukrainian Polissia, Cryptogamie, Algologie 20 (12), pp. 121-135 : 128

Mallomonas costata Dürrschmidt

( Fig. 2J )

DISTRIBUTION. — Widely distributed ( Kristiansen 2000).

REMARKS

Typically, the scale shield has 6-12 curved transversal ribs with one to three rows of pores between them ( Kristiansen &Preisig 2007). However, in our material the number of transverse ribs was 2-6 or sometimes they were weakly developed. There is a hole on the posterior border of the dome. Although this feature is clearly visible in published micrographs of M. costata (e.g. Dürrschmidt 1984; Asmund & Kristiansen 1986) it was not mentioned in the original diagnosis.It is likely that this hole is homologous with the opening of the dome in M. paludosa Fott and M. aperturae Siver (Siver 2018) . Siver (2018) proposed that the opening on the dome may provide a means for securing bristles to the scales and aiding in bristle rotation.

M. costata has an interesting taxonomic history. Péterfi & Momeu (1981) re-described the species which they identified as Mallomonopsis robusta Matv. using transmission electron microscopy and transferred it into the genus Mallomonas under the name Mallomonas robusta (Matv.) L.Ş.Péterfi & Momeu. Later Dürrschmidt (1984) pointed out that material of Péterfi & Momeu was not identical to Matvienko’s taxon in several key characters. Moreover, this combination is illegitimate because of a later homonym of Mallomonas robusta Matv. Thus, Dürrschmidt decided to describe a new species, M. costata ( Dürrschmidt 1984) .

Figures

FIG. 2. — Mallomonas Perty taxa from the Ukrainian Polissia: A, Mallomonas acaroides Perty emend. Iwanoff, SEM; B, Stomatocyst of Mallomonas cf. akrokomos Ruttner,SEM; C, Mallomonas annulata (D.E.Bradley) K.Harris, SEM; D, Mallomonas asmundiae (Wujek & van der Veer) K.H.Nicholls, SEM; E, F, Mallomonas calceolus D.E.Bradley, SEM; G, Mallomonas canina Kristiansen, SEM; H, Mallomonas caudata Iwanoff emend. Willi Krieger, SEM; I, Mallomonas corcontica (Kalina) L.Ş.Péterfi & Momeu, SEM; J, Mallomonas costata Dürrschmidt, SEM; K, Mallomonas crassisquama (Asmund) Fott, SEM; L, Mallomonas cratis K.Harris & D.E.Bradley, TEM;M, Mallomonas elongata Reverdin, SEM; N, Mallomonas heterospina J.W.G.Lund, SEM; O, Stomatocyst of Mallomonas mangofera var. foveata (Dürrschmidt) covered with scales, SEM. Scale bars: A, D-F, H-K, 1 µm; B, C, L-O, 2 µm; G, 0.5 µm.