A NEW SPECIES OF VOLVOX SECT. MERRILLOSPHAERA (VOLVOCACEAE, CHLOROPHYCEAE) FROM TEXAS¹

Area of Science:

• Phycology
• Algology
• Evolutionary Biology

Background:

• The genus Volvox L. is classified into sections based on morphological characteristics.
• Smith (1944) established the section Merrillosphaera for species lacking cytoplasmic bridges in adult cells.

Purpose of the Study:

• To describe a new species of Volvox from Texas, USA, belonging to the Merrillosphaera section.
• To differentiate the new species from existing Volvox species using morphological and molecular data.

Main Methods:

• Morphological examination of asexual spheroids, including cell counts and gonidia arrangement.
• Molecular phylogenetic analyses using five chloroplast genes and nuclear rDNA ITS regions.

Main Results:

• A new species, Volvox ovalis Pocock ex Nozaki et A. W. Coleman sp. nov., is described.
• V. ovalis exhibits ovoid/elliptical spheroids with 1,000-2,000 somatic cells lacking cytoplasmic bridges and 8-12 posterior gonidia.
• Molecular data places V. ovalis near Volvox spermatosphaera and Volvox tertius, but distinct morphological features differentiate it.

Conclusions:

• Volvox ovalis represents a new addition to the Merrillosphaera section.
• Distinct gonidial size and chloroplast morphology differentiate V. ovalis from closely related species.
• The study contributes to the taxonomic understanding of the Volvox genus.