. The Canadian field-naturalist. Natural history; Sciences naturelles. 2005 Nicholls: Two New Species of Testate Rhizopods 407. Figure 3. Pseudostomal apertures in nine different specimens of Cyclopyxis acmodonta illustrating the wide range in shape. The scale bar in Figure 3a applies to all Figures 3a-i. this species, the greatest variation was found in the aperture diameter (coefficient of variation = ; Table 1). The test of A. formosa appears to be of two major structural components: an underlying meshwork of irregularly sized and shaped meshes (Figure 5a), and an overlying sheet of el
. The Canadian field-naturalist. Natural history; Sciences naturelles. 2005 Nicholls: Two New Species of Testate Rhizopods 407. Figure 3. Pseudostomal apertures in nine different specimens of Cyclopyxis acmodonta illustrating the wide range in shape. The scale bar in Figure 3a applies to all Figures 3a-i. this species, the greatest variation was found in the aperture diameter (coefficient of variation = ; Table 1). The test of A. formosa appears to be of two major structural components: an underlying meshwork of irregularly sized and shaped meshes (Figure 5a), and an overlying sheet of elliptical-to-circular disc-like are- oles averaging about 3x4 urn. Small, but well-defined pores are located at the junctions of adjacent areoles so that each areole is surrounded by usually 4-5 pores (Figure 5b). This two-layered structure was revealed in the broken test of a specimen that apparently had a large piece of the outer areolar layer stripped off (Fig- ure 5a; but note the small patch containing the surface areolar layer in the lower right of Figure 5a). Discussion The genus Cyclopyxis contains a few large species with lobed pseudostomal apertures; consequently, the test structure of each had to be reviewed before any conclusions about the autonomy of C. acmodonta was established. Cyclopyxis impressa (Daday) Deflandre (= Difflugia lobostoma var. impressa Daday = Cen- tropyxis impressa (Daday) Da Cunha) is apparently restricted to a few locations in the Southern Hemi- sphere (Velho et al. 1996). All reports show a much larger test (300-561 |im in diameter) than that found for C. acmodonta; other differences include a very regularly shaped and symmetrical pseudostomal aper- ture with 5-8 lobes, a much greater diameter-to-height ratio, and a much greater degree of invagination of the pseudostome (to about 50% of the test height). Cyclopy- xis trilobata var. maxima Chardez, 1971, test size (D = 225-235; H = 110-140 urn) is close to C. acmod- onta. Although Chardez (1971)
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