Volvox ovalis, strain NIES-2569.
Volvox ovalis by Matthew Herron is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

Volvox ovalis was described by Hisayoshi Nozaki and Annette Coleman in 2011 from a strain collected near College Station, Texas. Colonies are often distinctly egg-shaped, up to 450 µm long, with 1000-2000 somatic cells and 8-12 gonidia. A member of the section Merrillosphaera, it is closely related to V. tertius and V. spermatosphaera:

Figure 3 from Nozaki & Coleman 2011. Phylogenetic position of Volvox ovalis within the Volvox–Yamagishiella group as inferred by maximum likelihood analysis of five chloroplast genes. Remember how I said volvocine taxonomy was a train wreck? Look at section Merrillosphaera…all three of them!

Like V. tertius and V. spermatosphaera, but unlike V. carteri, V. obversus and V. africanus, V. ovalis does not undergo asymmetric cell division during development. Somatic cells in adult colonies are not connected by cytoplasmic bridges.

There is only one strain of V. ovalis available, NIES-2569. The same strain is identified as UTEX LB 2960, but I can’t find it on the UTEX website. Their FAQs say

UTEX algal cultures are living organisms whose availability can changes from week to week. Cultures are removed from the online catalog if they are not considered healthy or if they are being cleaned from contamination. Recovering a culture, or bringing a culture back to health again, is labor intensive. It can take anywhere from 4 weeks to a few months before an organism is successfully recovered.

Let’s hope that’s all it is.