Learamoeba
Learamoeba Sawyer et al., 1998 (ref. ID; 7444 original paper)
Class Heterolobosea Page & Blanton 1985: Order Schizopyrenida Singh, 1952: Family Vahlkampfiidae Jollos, 1917 (ref. ID; 7444)
[ref. ID; 7444]
Diagnosis; Small free-living amoebae with trophozoites changing form a flattened multilobed flagellate form to a cylindrical limax form with one or more lobose eruptive pseudopodia (dimorphic). Nuclear division by promitosis with persistence of the nuclear membrane and nucleolus and without interzonal bodies. Infrequent transformationt to flagellates with four flabella and a V-shaped ventral groove. Cytostome at the base of the ventral groove and distinct cytopharynx. Cysts round to broadly oval, lacking pores and with a delicate ectocyst wall that may collapse onto the endocyst. (ref. ID; 7444)
- Learamoeba waccamawensis Sawyer et al., 1998 (ref. ID; 7444 original paper) reported author and year? (ref. ID; 7050)
Learamoeba waccamawensis Sawyer et al., 1998 (ref. ID; 7444 original paper) reported author and year? (ref. ID; 7050)
Diagnosis
Free-living amoeboe with taxonomic charactersitics of the genus (monotypic). Flattened flabellate forms with multiple broad-based pseudopodia emerging from any area around the periphery of the body. Temporary limax forms broad anteriorly and tapering posteriorly with eruptive pseudopodia and a clear hyaline zone approximately 1/4 to 1/5 of the length of the body. Limax forms approximately 32-50 um long (mean=38) and 4.4-9.9 um wide (mean=7.5). Flattened flabellate forms constantly changing shape without a distinct anterior-posterior orientation and rarely exceeding 50 um in greatest dimension. Rate of locomotion difficult to determine because of continuous change of shape, approximately 32-70 um/min. Nucleus round to elongate 4.4-7.7 um long (mean=5.2) and 2.7-5.5 um wide (mean=4.5), nucleolus round to elongate 3.3-4.9 um long (mean 3.8). and 2.2-4.4 um wide (mean=3.2) after staining with nuclear red. Nuclear division by promitosis without interzonal bodies. Cysts refractile and measuring 9-12 um (mean=10.3) in the rounded form and 10-15 um (mean=12.8) by 9-12 um (mean=10.4) in the broadly oval form. Cysts with an elevated delicate ectocyst that may collapse at one point on the cyst surface; pores absent. Transformation to flagellates rare to absent in liquid culture media. Flagellates with four flagella and a well-defined V-shaped ventral groove and cytostome. Growth at temperatures up to 44 degrees C. (ref. ID; 7444)
Descriptions
The internal transcribed spacer (ITS) sequences. (ref. ID; 7050)
Notes
Learamoeba waccamawensis from soil at Lake Waccamaw is characterized by the rapid formation and disappearance of multiple pseudopods from any part of the body, and a progressive change to an elongate limax form with broad blunt anterior pseudopodia (dimorphic). Similar dimorphism in another soil amoeba has been described by Page (1987, 1988) for Stachyamoeba lipophora, an amoeba that changes temporarily from a flattened expanded form to a less frequent Vahlkampfia-like limax form. Rates of locomotion for L. waccamawensis are difficult to estimate since the amoebae continuously produce new pseudopodia, and change direction with the nucleus becoming elongate and bending when located at the junction where a new pseudopod is extended. The few flagellates that were available for study were similar to those produced by Tetramitus rostratus, having both a distinct cytostome, V-shaped ventral groove and four flagella. Observations on T. rostratus ATCC 30216 showed, however, that this amoebae does not convert to a limax form nor assume a flattened flabellate form. Careful study of L. waccamawensis also showed that in fresh preparations very fine and delicate filamentous projections on the flabellate forms briefly appeared and disappeared within seconds. The very transient nature of the clustered filaments, however, does not agree with criteria set forth by Page (1972) to justify their description as uroidal structures of diagnostic value. (ref. ID; 7444)
Type habitat
Fecally contaminated organic soil from a ditch at Lake Waccamaw, NC. (ref. ID; 7444)
Type culture
Learamoeba waccamawensis ATCC Strain 50579. (ref. ID; 7444)