A new Marasmius to look out for!

Marasmius brunneolorobustus – Marasmius ‘robust brown’

Marasmius brunneolorobustus

It is exciting to have another recognisable species in the genus Marasmius named and published. This one has been lurking under Marasmius haematocephalus for a long time, but it didn’t fit too comfortably there as it is generally bigger, more robust, usually with darker colours (reds, browns and purplish-browns) and almost twice as many gills (21 – 30 full lamellae.) It may be solitary, though occasionally gregarious and often occurs with other litter-rotting Marasmius. Its substrate is usually twigs or well-rotted wood, rather than leaf litter. It has a small, off-white basal disc attaching the wiry black stem to the wood. While the usual range of cap diameter is 8 – 15mm, large specimens (to 25 mm) occur occasionally.

To date this species has been found in tropical and subtropical rainforests, extending well south into New South Wales.

Marasmius brunneolorobustus

A full description is found in Fungal Planet. It has also been written up in Fungi of Queensland on the Queensland Mycological Society website. New sightings are being recorded on iNaturalist, all of which add different images of the taxon, illustrating the variation in colour and size. It will be valuable in learning its full distribution for FungiMap members to add new sightings to the “Fungimap Australia” project on iNaturalist, which then become part of the Atlas of Living Australia.

Microscopic examination and DNA analysis of this new species show that it is not closely related to M. haematocephalus. In fact, the original M. haematocephalus from South America, has recently been sequenced and my study is showing that the Australian species which we’ve called ‘haematocephalus’ are completely different taxa …… but that is another story still in the making, to be told later!

Story and photos by Frances Guard

Marasmius brunneolorobustus
Marasmius aff haematocephalus
Marasmius haematocephalus