So far, I have found Trachelophyllum apiculatum exclusively in the Simmelried. Mostly in old samples with few plant remains.

The literature on Trachelophyllum apiculatum is quite heterogeneous, and there are different reports regarding the size, the extrusomes, or the existence of the epicortical layer. Kahl (1935) provides only a very brief description. He gives a length of 125–150 µm and does not mention the extrusomes or an epicortical layer. Foissner published a redescription in 1983. Here, Foissner gives a body length of only 90–110 µm and 13 µm length for the rod-shaped extrusomes. His drawing from 1983 (s. drawing a, above) shows a very slender specimen without an epicortical layer. In 1995, Foissner, Berger, Blatterer, and Kohmann published an further description of Trachelophyllum apiculatum, in which the authors described the species without an epicortical layer, with a length of 90–180 µm and 15 µm long extrusomes. Seven years later, in 2002, Foissner, Berger, and Agatha published the results of their investigations on a population of Trachelophyllum apiculatum from Venezuela. In this publication, the authors were able to detect the epicortical layer, into which intricately shaped scales (lepidosomes) are embedded. The size of the specimens is given as 100-200 µm, and the length of the extrusomes as 10-20 µm. The epicortical layer is described as very hyaline with a thickness of 1–2.5 µm.

This rough overview of the available descriptions of Trachelophyllum apiculatum gives an impression, how the data has changed over time with the number of specimens and populations examined. Foissner, Berger, and Agatha (2002) therefore assume that the species is very variable and that there may possibly be a species complex behind it.