Lacogromia brunneri (Le Blanc, 1886) Siemensma et al., 2017
Syn.: Gromia gemma Penard 1899.
Remarks: Penard(1899) states that Blanc’s G. brunneri might infact represent three different species: G. brunneri, G. gemma and G. squamosa. However, Blanc described the largest specimens of G. brunneri (500–1000 µm) as being ovoid to almost spherical, and the smallest specimens (200 µm) as spindle-or bottle-shaped. This description does not fit the features of G. squamosa, which is a large spindle-shaped species,up to 1000 µm. Morphotype A of L. cassipara is in this respect similar to Blanc’s G.brunneri, with larger specimens being almost spherical and smaller specimens being spindle-shaped.
In the original description of G. gemma, Penard (1899) mentioned the thick internal mucous layer as an important character. In a later publication (Penard 1902), he remarked that this layer is not visible in living cells, but only in stained preparations. In 1905 Penard also observed such an internal mucous layer in G. brunneri. I was able to repeat his experiment of pressing cells out of their tests, but what Penard described as a mucous layer is, in my opinion, just a layer of viscous hyaloplasm. In a later description of G. gemma, Penard (1905) did not even mention this mucous layer, which should be so characteristic. In summarizing the main differences between his G. brunneri and G. gemma he only mentioned the size of the test, the thickness of the test wall and the oblique aperture. According to Penard (1905) further differences concern the test wall that is much thinner in G. brunneri than in G. gemma. His 1902 illustration of G. brunneri shows an extremely thin wall, almost a membrane with some attached particles. However, the numerous specimens in his two slides labeled “G. brunneri”, have a very thick test wall, between 20 and 77 µm. I compared the only specimen of G. gemma in the Penard Collection with those of G. brunneri, and found no significant difference. All these specimens are also very similar to the drawings given by Blanc. Penard (1905) remarked that G. brunneri and G. gemma might be one species, as he considered the three main differences mentioned above as not very important. Based on Penard’s statement and our observations of his slides we consider G. gemma as a junior synonym of G. brunneri. Penard also supposed that G. gemma is an adult stage of G. brunneri, but that seems to be less likely considering the dimensions given by Blanc for G. brunneri (200-1000 µm) and those by Penard for G. gemma (200-600 µm). The 33 specimens of G. brunneri preserved in the Penard Collection measure 160-670 µm.