Callicostella prabaktiana

Callicostella prabaktiana is a creeping moss with a wide distribution in the Asian tropics, where it grows on wet rocks and shaded riverbanks, among others. It resembles the species Callicostella papillata very much, however, it can be discerned from the latter by missing papillae (tiny bumps) on the leaf cells as well as a less serrate leaf margin in the tip area. It is often considered a variety of this species, though (C. papillata var. prabaktiana). The creeping, irregularly ramified shoots have a flat leaf pattern and look a bit like those of the Vesicularia species. However, C. prabaktiana can be discerned from the latter e.g. by a thick double midrib reaching almost to the leaf tip, rather roundish, thick-walled leaf cells and its tongue-shaped shortly acute leaf form.
This species is hardly known as aquarium moss yet. It was imported from Thailand to Germany several years ago together with so-called "Worm Moss" (a foliose liverwort), and Heiko Muth (Goettingen) identified it by means of the revision by Mohamed & Robinson (1991) as C. prabaktiana.

Callicostella prabaktiana may grow very slowly when cultivated submersed, however, it seems to be quite undemanding. Its growth habit makes this moss especially interesting as ephiphytical plant: its shoots nestle against the substrate and attach to it very tightly with their rhizoids. Loose shoots grow downwards, much like those of "Weeping Moss" (Vesicularia ferriei). Attached to rocks or driftwood with fishing line or something comparable, C. prabaktiana forms a dense "flowing" mat.

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