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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ovalopodium

Ovalopodium Sawyer, 1980 (ref. ID; 3847 original paper)

[ref. ID; 3847]
Diagnosis; Small broadly ovoid ameba with glycocalyx devoid of scales or "hull-units"; anterior and lateral margins smooth; posterior margin with small or inconspicuous spines; protoplasm of posterior hump with broad-based uroid-like spines projecting over and slightly beyond the posterior margin; expulsion vesicle small and distinct in living ameba; refractile endoplasmic granules absent; nuclear division by mesomitosis, with disappearance of the nuclear membrane during prophase. (ref. ID; 3847)
Etymology; The genus name pertains to the nearly circular to ovoid outline of amebae in locomotion. (ref. ID; 3847)
Type species; Ovalopodim carrikeri sp. n. [by monotypy] (ref. ID; 3847)
  1. Ovalopodim carrikeri Sawyer, 1980 (ref. ID; 3847 original paper)

Ovalopodim carrikeri Sawyer, 1980 (ref. ID; 3847 original paper)

Diagnosis

Living amebae in active locomotive average 26x27 (18-35x25-36 um). Nucleus single, 4 um in diameter, with central nucleolus 3 um in diameter; feeding on bacteria. (ref. ID; 3847)

Comments

Living specimens of O. carrikeri observed in full-strength seawater are broadly circular to void in locomotion. On agar medium the amebae are ovoid, indistinct, and place in contrast to the optical density of the agar. Anterior and lateral margins are smooth, or slightly irregular, or rippled, but posterolateral and posterior margins have short broad-based spines or filaments. The spines arise from the posterior hump and project dorsally over the posterior body margin for a short distance. After staining, the spines are seen to project from the pellicular rather than from the granular endoplasm. The granular endoplasm contains a distinct nucleus, numerous clear vesicles, and small digestive vesicles, but no refractile granules. In stained preparations, the interphase nuclei are spherical, with a dark-staining nuclear envelope and central nucleolus. The nuclear space is filled with dark granules that sometimes are tightly packed to form a wide ring. Prophase and metaphase stages were not found on stained slides. During anaphase, the spindle fibers are poorly stained and indistinct. Polar chromosomes form a curved bar; clear zones or halos are absent. During nuclear reconstruction, the nuclear envelope is pale, but nucleolar fragment of different sizes stain well. No pronounced glycocalyx or tectum with scales, often observed in other species of Cochlipodiidae, exist in O. carrikeri. Ovalopodium carrikeri differs from the type species of the family by its lack of scales to "hull-units", the tectum of Bark (1973), and its inability to form cysts. (ref. ID; 3847)

Etymology

The species is named in honor of Dr. Melbourne R. Carriker, Professor, College of Marine Studies, University of Delaware, Lewes, Delaware. (ref. ID; 3847)

Habitat

Known only from oyster holding trays, University of Delaware, Lewes DE. (ref. ID; 3847)