Gastronauta

Gastronauta Butschli, 1889 (ref. ID; 2013, 4730, 4819)

Class Kinetofragminophora: Subclass Hypostomata: Order Cyrtophorida: Suborder Chlamydodontina (ref. ID; 2013)
Family Chlamydodontidae Stein, 1859 (ref. ID; 4819)

[ref. ID; 2013]
Body outline shape oval, dorso-ventrally flattened with dorsal surface strongly arched. Somatic ciliature reduced to ventral surface with exception of 2 short kineties on the dorsal surface. The oral aperture is very long and narrow and lies transversely across the body, it is not supported by trichites. On the right of the body there are several longitudinal kineties of which three of four extend forward and curve around the apex. Between these curved ends and the oral aperture are several curved pre-oral kineties. There is a pre-oral kinety which entirely surrounds the oral aperture, this is field of kineties which transverse the body width (although there may be a large gap in the mid-line). Macronucleus large, irregular shape located in posterior half of body. There are 2 contractile vacuoles, one anterior, one posterior.
Quote; Colin R. Curds "British and other freshwater ciliated protozoa Part I Ciliophora: Kinetofragminophora" Cambridge University Press, 1982 (ref. ID; 2013)

Gastronauta clatratus Deroux, 1976 (ref. ID; 4609, 4819) reported author and year? (ref. ID; 1629)
Gastronauta derouxi Blatterer & Foissner, 1992 (ref. ID; 4819 original paper)
Gastronauta membranacea Kahl, 1931 (ref. ID; 4730)
Gastronauta membranaceus (ref. ID; 191)
Gastronauta membranaceus Buetschli, 1889 (ref. ID; 4609, 4819)
Syn; Gastronauta runcina Wilbert, 1971 (ref. ID; 4609)
Gastronauta membranaceus Engelmann, 1875 (ref. ID; 1622, 1629)
Gastronauta runcina Wilbert, 1971 (ref. ID; 4609, 5462)
See; Gastronauta membranaceus (ref. ID; 4609)

Gastronauta derouxi Blatterer & Foissner, 1992 (ref. ID; 4819 original paper)

Diagnosis

In vivo about 60-70x40 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. (ref. ID; 4819)

Descriptions

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 (mostly 16 in Madeiran, 18 in Kenyan population) 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 kineties 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. 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. (ref. ID; 4819)

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. (ref. ID; 4819)

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. (ref. ID; 4819)
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. (ref. ID; 4819)
Gastronauta derouxi nov. spec.: Postoral field non-ciliated; dorsal brush consists of about 7 groups of evenly spaced, paired basal bodies along anterior dorsal margin. In moss and soil. Deroux & Dragesco (1968) provided a description and illustrations (including four encystment stages and two stages of morphogenesis) of a moss dwelling Gastronauta membranaceus which obviously fits the diagnosis of G. derouxi. Probably all soil records of G. membanaceus (e.g. Blatterer & Foissner 1988; Stout 1961, 1970) belong to G. derouxi; unfortunately, none is substantiated by an investigation of the dorsal brush. The Roscoff (France) population of G. derouxi differs from the type having slightly are dorsal brush pairs (7-9) and more kineties in the right (12-13) and left (6) ciliary field; it is very similar to our African population (7-10 dorsal brush pairs, 5-6 preoral kineties, 13 and 5-6 kineties in the right and left ciliary field, respectively). Thus, we consider the French, the Madeiran and the Kenyan population as conspecific. (ref. ID; 4819)

Etymology

We dedicate this new species to Dr. Gilbert Deroux who significantly contributed to the knowledge of cyrtophorid ciliates. (ref. ID; 4819)

Type location

Garajau Kap, Madeira, Portugal, N32 degrees 50', W17 degrees 0'. (ref. ID; 4819)

Type specimens

A holotype and a paratype of G. derouxi as 2 slides of protargol impregnated cells have been deposited in the collection of microscope slides of the Oberosterreichisches Landesmuseum in Linz, Austria. (ref. ID; 4819)