VOLVOX POCOCKIAE, A NEW SPECIES WITH DWARF MALES1

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SUMMARY: Volvox pocockiae is described as the second species in the section Janetosphaera. The somatic protoplasts are connected by cytoplasmic strands approximately the same diameter as flagella, and the construction of the spheroid is identical to that of V. aureus. Asexual reproduction by the division of gonidia differs from that in V. aureus in the enlargement of the gonidium prior to its division to form the embryo. Sexual reproduction is very similar to that in V. spermatosphaera, a species in the section Merrillosphaera without cytoplasmic connections. Dwarf males are formed in the posterior end of the parental spheroid, and, as in V. spermatosphaera, the dwarf males are composed exclusively of androgonidia with no sterile somatic cells. Females are facultatively asexual spheroids, the gonidia of which function as eggs. The single biflagellate zoospore produced by the germinating zygote undergoes cleavage to form a germling spheroid. The differentiation of gonidia in the asexual embryo and in the germling spheroid is evident only after inversion and enlargement of the spheroid have begun.

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