Why the Java Fern, Microsorum pteropus, is now called Leptochilus pteropus

Leptochilus pteropus, commonly known as the Java Fern, is a popular aquatic plant species used in freshwater aquariums. Renowned for its hardiness and ease of care, it thrives in various water conditions and lighting levels, making it suitable for both beginner and experienced aquarists. It is known for its distinctive, textured fronds and ability to attach to rocks or driftwood.
The native range of Java Fern spans across Southeast Asia, particularly in countries such as Malaysia, Thailand, Indonesia, and some parts of India. It typically grows along riverbanks, on rocks, or attached to driftwood in shaded areas with moderate water flow. This plant is commonly found in tropical regions with warm temperatures and high humidity, where it thrives in both submerged and partially submerged conditions.
The fern genus Leptochilus, which encompasses around 50 species in subtropical to tropical Asia and the Pacific islands, has had a history of ambiguous classification. Previously, species within this genus were scattered across various genera due to purely morphological similarities like their sori—clusters (spore-producing organs). However, recent molecular studies have provided clarity.
The reclassification of Microsorum pteropus to Leptochilus pteropus is an example of how advancements in molecular data analysis can refine our understanding of plant taxonomy. DNA sequencing has shed light on the true phylogenetic position of this fern, leading to a more accurate classification.
Six major clades within Leptochilus have been identified, each with distinct molecular, morphological, and geographical characteristics. The previously recognised Microsorum pteropus now belongs within Leptochilus. There may very well even be more than one species in the Leptochilus cf. pteropus clade, as genetic differences have been found between the geographically isolated groups in its range.
The spore data of Leptochilus pteropus, with its long spiny and globular elements, aligns with the characteristics of the Leptochilus genus, supporting its new classification. It is now considered most closely related to Leptochilus cf. macrophyllus. It is highly likely that other members of the Leptochilus genus such as L. hemionitideus are also aquatic or able to spend at least part of their lifecycle underwater.