Volvox ovalis


Volvox ovalis

Volvox ovalis, strain NIES-2569.Creative Commons License
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 sp. nov. within the advanced members of the Volvocaceae (Volvox–Yamagishiella group; Nozaki 2003, Nozaki et al. 2006), as inferred from 6,021 bp of five chloroplast genes. The tree was constructed by the maximum-likelihood (ML) method based on the heuristic search using the tree bisection-reconnection branch-swapping algorithm by PAUP 4.0b10 (Swofford 2002). Branch lengths are proportional to the genetic distances, which are indicated by the scale bar above the tree. Numbers above branches represent 50% or more bootstrap values (based on 100 replications) of the ML analyses using nearest-neighbor interchange branch-swapping algorithm. Numbers without and within parentheses below branches are 50% or more bootstrap values (based on 1,000 replications) of maximum-parsimony and neighbor-joining analyses, respectively.

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. carteriV. 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.

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