Arnoldiella

Lore & Background

The genus name Arnoldiella honors Vladimir Mitrofanowitch Arnoldi, a Russian professor of biology who lived from 1871 to 1924. The alga forms a prostrate layer of coalescing filaments, from which arises a dense cushion of short, coarse, erect filaments. Cells of the prostrate layer contain one or several nuclei, while cells of the erect filaments are multinucleate. The erect filaments are uniseriate, one cell thick, and may have primary, secondary, or tertiary branches. Cells of the erect filament are cylindrical, becoming shorter near the apex; each cell contains a parietal, net-like chloroplast with numerous pyrenoids. Apical cells may be rounded or pointed. The cell walls are thick and lamellated, at least for the cells near the basal parts.

Reader's Guide

Arnoldiella is a freshwater genus that grows as an epiphyte on hard surfaces such as mollusc shells and the upper carapace of various turtle species. It may also grow on rocks, wood, metal, or other algae such as Cladophora. Its reproductive structures include zoosporangia produced at the ends of filaments, as well as akinetes. Zoospores possess four flagella and a stigma. The genus is placed within the family Pithophoraceae, and its morphology—particularly the multinucleate cells of erect filaments and the lamellated cell walls—distinguishes it within the group. The naming after Professor Arnoldi reflects a tradition of honoring notable phycologists, though the article provides no further details on the genus's discovery or subsequent research.

Did You Know?

• Arnoldiella is named after Russian biology professor Vladimir Mitrofanowitch Arnoldi (1871-1924).
• Cells of the erect filaments are multinucleate, while prostrate layer cells contain one or several nuclei.
• Zoospores of Arnoldiella have four flagella and a stigma.