Dorsal infraciliature of Gastronauta derouxi (FOISSNER & BLATTERER, 1992).DBK=dorsal brush dikinetids. Collected from an ephemeral puddle on a grass lawn in Boise, Idaho. July 2007. Stained by the silver carbonate technique (Foissner,W. Europ. J. Protistol.27:313-330;1991).Brightfield. This image was taken by William Bourland. He now uses a Zeiss Axioskop 2 with Spot Insight and Spot Flex CCD cameras (Diagnostic Instruments). Image copyright: William Bourland, image used under license to MBL (micro*scope).
download as pdf file
download large file
From the collection
Freshwater and Terrestrial Microbes of Idaho (USA) and Elsewhere
|Description of Gastronauta derouxi: Gastronauta derouxi Blatterer & Foissner, 1992.
Diagnosis; In vivo about 60-70 x 40 um. Postoral field non-ciliated. 5-6 left and 5-6 right postoral kineties, 6-8 right kineties, 4-6 praeoral kineties. Dorsal brush along anterior dorsal margin, consists of about 7 evenly spaced groups of paired basal bodies. In moss and soil.
Description; Roughly elliptical, right side convex, left almost straight. Acontractile but very flexible. Dorsal hump distinct, sometimes projecting above deeply grooved ventral surface, with furrows and prominent anterior slope. Anteriorly about 3:1, posteriorly 2:1 flattened. Macronucleus in mid-body, ellipsoid, contains small, spherical chromatin bodies surrounding hyaline area having central globule. Micronucleus spherical, sometimes rather distant from macronucleus. 2 contractile vacuoles, the upper close below oral opening between 1st and 2nd inner kinety of right postoral field, the other near posterior end between 3rd and 4th (or 2nd and 4th; Deroux & Dragesco 1968) inner kinety of left postoral field. Circumoral kinety narrow-elliptical, crosses almost entire width slightly above mid-body, its cilia form lamellated structure in vivo. Cytopharyngeal basket narrow (1/4-1/5 of circumoral kinety length), recognizable only after protargol impregnation, tapering and irregularly curved, extends to dorsal side. Cytoplasm colourless, with some food vacuoles probably containing bacteria and fungal spores. Movement slowly gliding, thigmotactic. Ventral infraciliature very similar to that of G. membranaceus. 16-18 ventral kineties separated by non-ciliated postoral field; accompanied by argyrophilic fibre at right. 5 postoral kineties in right field, anterior end of inner kinety sharply bent to left crossing non-ciliated field. 6 kineties extend on right and anterior margin of cell. 4 (5-6 in Kenian population) praeoral kineties between right ciliary field and oral opening, and 3 short vertical kinety fragments at left cell margin. Kineties of left field posteriorly shortened, slightly bent to left at circumoral kinety, leftmost row usually connected by loosely arranged basal bodies to leftmost vertical kinety fragment. Dorsal brush along anterior and anterior left dorsal margin, consists of 5-7 (8-10 in African population) evenly spaced groups (usually pairs, rarely triplets or singles) of 4 um long cilia. Right of median, near mid-body, an argyophilic structure, possibly the cytopyge.
Comparison with related species; There are 3 well defined species of Gastronauta distinguished by the composition of the dorsal brush and the arrangement of the ventral kineties.
G. membranaceus (Butschli, 1889): Postoral field non-ciliated; dorsal brush consists of 2 short kineties, viz., a row each at anterior end and in anterior third near left margin of cell. Lives in fresh and brackish water. The identification is based on Blochmann (1895), who provided the first illustration, even including the typical dorsal brush; however, very likely he mixed up the positions of the contractile vacuoles or illustrated them side-inverted. Considering the highly characteristic dorsal brush, Gastronauta sp. in Deroux & Dragesco (1968) and Gastronauta runcina Wilbert, 1971 must be considered as junior synonyms of G. membranaceus. Klein (1927) provided the first silver impregnation of the ventral side. Penard (1922) supposedly found G. membranaceus in mosses; however, his specimens lack the non-ciliated postoral field and thus resemble G. clatratus Deroux, 1976. Penard did not mention the dorsal brush, thus his population cannot reliably assigned.
G. clatratus Deroux, 1976: Postoral field ciliated; dorsal brush consists of 4 short kineties, viz., 1 at anterior end, 1 at posterior end (overlooked by Deroux) and 2 near anterior left margin of cell. Lives in fresh and brackish water. The brush pattern is based on the reinvestigation by Foissner et al. (1991) and on a personal communication by Dr. G. Deroux. Deroux (1976), Jutrczenki (1982), Wilbert (1986) and Song Weibo & Wilbert (1989) each obviously overlooked one of these kineties; Wilbert even illustrated one kinety at the wrong cell margin.
Type location; Garajau Kap, Madeira, Portugal, N 32 degrees 50', W 17 degrees 0'. (ref. ID; 4819) |