title: Stenamoeba polymorpha, a New Species Isolated from Domesticated Horse Equus ferus caballus.
abstract: A new species of lobosean amoeba, Stenamoeba polymorpha n. sp., was isolated from the diarrheic stool of a domesticated horse in Great Falls Virginia, U.S. It shares characteristics with the five other described Stenamoeba species. However, electron microscopy revealed S. polymorpha has a substantially thickened cell surface lamina. Under light microscopy, the amoebae had a dynamic polymorphic appearance because hyaloplasm readily formed and resorbed subpseudopodia from any peripheral region of the cell. While in locomotion, the amoebae produced subpseudopodia that led and alternated the direction of movement with an apparent zigzag path. Sometimes, stationary amoebae had a vertical cell posture that was substantially taller than wide or long. The new species description is also supported by small subunit ribosomal ribonucleic acid gene analyses using phylogenies with both broad and narrow taxon sampling, pairwise nucleotide comparisons, and in-silico secondary structure predictions. The latter suggested Stenamoeba spp. discriminatory motifs in variable region eight. Stenamoeba polymorpha n. sp. is the first of its genus to be recovered from mammal feces, the first to yield a potential group one intron and the second described from North America. Here, the phylogenies suggest Stenamoeba limacina is this new species' nearest known relative.
authors.affiliation: Math Science and Engineering Division, Northern Virginia Community College, 8333 Little River Turnpike, Annandale, Virginia, 22003. mtpeglar@gmail.com, mpeglar@nvcc.edu.|School of Systems Biology, George Mason University, 10900 University Boulevard, MSN5B3, Manassas, Virginia, 20110. mtpeglar@gmail.com, mpeglar@nvcc.edu.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Peglar
authors.affiliation: Environmental Science and Policy Department, George Mason University, 4400 University Drive, Fairfax, Virginia, 22030.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Nerad
authors.affiliation: Department of Biology, Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, 10964.
authors.forename: O Roger
authors.initials: OR
authors.lastname: Anderson
mesh_terms: D000562:Amebiasis / Q000469:parasitology / Q000662:veterinary*; D000656:Amoeba / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000648:ultrastructure; D000818:Animals; D000829:Animals, Domestic / Q000469:parasitology; D016054:DNA, Protozoan / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D006734:Horse Diseases / Q000469:parasitology*; D006736:Horses; D010802:Phylogeny
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal
keywords: Amoebae; SSU-rDNA gene phylogeny; SSU-rRNA secondary structure; amphizoic; fine structure; locomotory form; morphotype; polytactic