Studies on North Indian Volvocales. VI. On the life cycle and cytology of a new member of Phacotaceae, Dysmorphococcus sarmaii sp. nov.
This paper deals with the morphology, reproduction, and cytology of a new species of Dysmorphococcus, viz., Dysmorphococcus sarmaii sp. nov. (Phacotaceae, Volvocales) from India. The lorica of this flagellate displays a remarkable morphological variability in nature as well as in culture under laboratory conditions. The alga is characterised by an anteriorly bilobed pentagonal lorica ornamentated with polygonal pores, a massive globose chloroplast that lacks a pyrenoid and almost completely occupys the protoplast, a prominent red stigma, two contractile vacuoles located anteriorly near the insertion of the flagella, and flagella that are equal to or a little longer than the length of the lorica. The pentagonal lorica of the present taxon differs remarkably from the broadly ovoid to globose lorica of D. variabilis Takeda, D. coccifer Korschikoff, and D. globosus Bold and Starr. The lorica of D. sarmaii is somewhat comparable in shape to D. punctatus Fott because of its bilobed anterior but differs from the latter in its ornamentation. The massive globose chloroplast lacking a pyrenoid in the present alga differs remarkably from the other species of this genus where the chloroplast possesses one or several pyrenoids. In addition, asexual reproduction, which is accomplished by division of the protoplast within the lorica, results in the production of 8–16 zoospores as compared with the earlier record of 2 and 4 zoospores in this genus. The alga is heterothallic and sexual reproduction, which was not known for the earlier described species of the genus Dysmorphococcus, takes place by isogametes produced 16–32(–64) per cell. The chromosome number recorded for D. sarmaii is n = 10.