Three aquatic Distoseptispora from the Philippines

Wood that falls into a stream does not decay the way wood lying in a forest does. The conditions differ: constant flow, less oxygen, different shredding animals and a different fungal community. Aquatic wood-decaying fungi, called lignicolous, are central to that process and yet poorly studied — especially in the tropics.

Jaymee Bagacay's team surveyed lignicolous aquatic fungi in the Philippines and recovered four taxa of Distoseptispora. Multi-locus phylogenetic analyses on a concatenated dataset of ITS, LSU, RPB2 and TEF1-α sequences, together with detailed morphological examination, confirmed three of them as new species: Distoseptispora antiqueana, D. iloiloensis and D. panayensis.

The fourth strain, UPVMICC 25–0100, clustered with the ex-type strain of D. septata with very strong statistical support — 100 per cent under maximum likelihood and a posterior probability of one. That is a new geographic record for the species, not a new species.

The paper also tidies the genus. Phylogenetic inference supported synonymising D. thailandica under D. phangngaensis and D. mengsongensis under D. fasciculata. In taxonomy such a correction is worth as much as describing something new: two names for one species corrupt every later analysis of distribution.

The specific epithets point at places in the Philippines — Antique province, the city of Iloilo and the island of Panay. It is a typical pattern in tropical mycology: diversity is vast, and names appear faster than knowledge of the ecology of the organisms being named.

How such fungi are collected explains why so few appear in checklists. They are not visible in the stream. Submerged branches and pieces of wood are collected, carried in damp containers and incubated in a moist chamber for weeks, until sporulating structures appear on the surface.

The second method is to collect the foam that gathers against obstacles in the current. Foam traps spores washed down from the whole catchment, so a single sample gives a far wider survey than one piece of wood. Both methods need patience and a microscope, and neither can be automated.

What the paper establishes

Distoseptispora antiqueana, D. iloiloensis and D. panayensis were described from submerged wood in Philippine fresh water. The authors combined morphology with ITS, LSU, RPB2 and TEF1-α, while a fourth isolate was assigned to known D. septata, providing a new geographic record. The study also treats D. thailandica as a synonym of D. phangngaensis and D. mengsongensis as a synonym of D. fasciculata. “Aquatic” records the habitat and submerged dead-wood substrate; it does not prove an obligately aquatic life cycle. Province- and island-derived names do not demonstrate endemism. Without systematic sampling across many streams, the records cannot establish full distributions or rarity, and a taxonomic description is neither an IUCN assessment nor a quantitative test of decomposition.