world of amoeboid organisms

Bullinularia minor
B. minor – from Hoogenraad and De Groot, 1948

Bullinularia minor Hoogenraad & De Groot, 1948

Diagnosis: Habitus, shape, color and structure of the test showed in general many striking resemblance with that of B. indica; all this features, however, often showed slight aberrations, diffi­cult to describe in words or to delineate in drawings. As seen in the direction of the oral-aboral axis, the test showed a very regular broad elliptical or nearly circular outline, the border of which being usually very smooth by the lack of projecting xenosomes. Observed from aside, the form appeared strongly compressed. The color varied but little; it was dark yellow, with a some­times more bright, in other cases more dark brown shade. The thickness of the wall seemed to be but small; therefore, the test never showed the opaque, sometimes nearly black ap­pearance of that of B. indica. Especially in the bright tinted individuals the cleft of the aperture shone feebly but distinctly through the fundus wall of the test.

In the structure of the test in general the chitinoid cement predominated, especially on the oral sides. On the other hand, the xenosomal covering was but mode­rately developed; it existed mainly of some scattered quartz grains, and among them sometimes rather numerous organic particles, a structure, quite different from the often so dense and blunt mosaic which adorns the tests of B. indica and also from those of Trigonopyxis arcula from some loca­lities.

The structure of the oral field is in the main the same as that of B. indica. The cleft of the aperture in vertical projec­tion showed itself narrow elliptical with undulating margins, upper and under lip normally developed, with, on account of a more dense accumulation of the pseudo-chitin, a thickened and darker colored rim, the upper lip often projecting in a triangular tip. By the usually great transparency of the test, it was possible to study the structure and the shape of the aper­ture also from aside. In this way, the aperture, lying in a distinct inward bending of the test plane, upper and under lip appeared to be placed on very different levels. In many cases the conse­quence of this was that the plane of the aperture stood more or less perpendicular on the oral plane of the test, and the aperture itself, so observed, appeared much less cleft-like and wider than one would presume by observation of the test in the projection position in which it usually presents itself. Also in B. indica, a similar phenomenon can sometimes be observed, but seldom so distinct as in the case of B. minor. The pores in the upper lip, a feature so extremely charac­teristic for B. indica, were in B. minor in regard to number, size and arrangement, normally developed.

Penard (1912) mentions variants of B. indica also of unusu­ally small dimensions: long 130 – 170 µm, and 120 – 125 µm. Also Jung (1934) observed such small forms, among them one of 90 (126) µm length. As may be seen from the results of our mea­surings our form was yet considerably smaller, moreover, transitory forms between this form and the also in the sample occurring B. indicia being entirely absent, we may the more be justified in describing this form as an autonomous species.

After discovering it in a sample from New Zealand, we found it again in material from Greenbank (N.J., U.S.A.), in an almost identical form, but only in one single specimen.

All from Hoogenraad & De Groot, 1948

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