Olive Salver, Catinella olivacea

On the morning of the last Sunday of November Vanna, James and I were in Whitlingham Woods (part of Whitlingham Country Park), near Norwich, searching for harvestmen in the leaf litter.

Vanna, at the front, turned over a big piece of rotten wood and called us over to see some lovely cup fungi she’d found, growing on the underside of the log.

We took photos and, when we arrived home, identified the fungi as the Olive Salver, Catinella olivacea (note 1).

Small but very beautiful

Catinella olivacea is a small but very beautiful cup fungus. The cup surface is a dark olive-green and looks like a decorative ceramic dish, making the English name of Olive Salver very appropriate. The cups have a yellowish furrowed margin. Individual cups can eventually reach 13mm across but ours were much smaller than this.

Like other cup fungi Catinella olivacea is an Ascomycete. The cup (the apothecium) is the fruiting body of the fungus and it is formed of a mixture of sterile tissues and special, elongated sacs known as asci that shoot out their spores (note 2).

An unusual way to spread spores

Most cup fungi grow on top of soil, wood or other substrates and their spores are dispersed in air currents but Catinella olivacea is tucked away under rotting logs and has evolved another strategy to disperse its spores. The fertile surface of its apothecium is gelatinous at maturity and when the ascospores are shot out they are trapped in sticky droplets. When a passing invertebrate walks across the surface of the cup the droplets with spores stick onto the visitor and it will move them elsewhere. Rotting logs are home to springtails, woodlice, millipedes, centipedes and other arthropods, including the harvestmen Vanna was looking for, so there is no shortage of potential spore spreaders (note 3).

I was tempted to take a piece of Catinella olivacea to look at more closely but ours were young specimens and it seemed a shame to disturb them. The cup surface turns purple when potassium hydroxide is applied to it and the spores look like tiny footprints. (See also Malcolm Storey’s photos on the Discover Life website.)

Olive Salver, Catinella olivacea

Quite a rare find

At the time of writing there are 125 records of Catinella olivacea in the NBN Atlas, from Cornwall to Cumbria and North Yorkshire and in Northern Ireland. Ours was the ninth record of the species in Norfolk and the first since 1999.

The Global Biodiversity Information Facility (GBIF) website shows the global distribution of Catinella olivacea: it occurs in other parts of Europe and in North America. There is are outlying records from Asia (the far east of Russia), South America (French Guiana) and Africa (Democratic Republic of Congo) (note 4).

Who knows how common Catinella olivacea actually is? Læssøe and Petersen describe it as “occasional” and Sterry and Hughes say “uncommon to rare” (note 1) but the Naturespot website says it is “quite common”.

It is likely to be under-recorded. In the course of a normal fungal foray Catinella olivacea would be an unlikely find because everyone looks on top of logs, rather than beneath them. Some logs are just too big to lift anyway. Not all logs are suitable: they need to be well rotted and have enough of a gap underneath for Olive Salvers to grow. Old logs can be scarce: too many are tidied away or used for firewood (note 5).

It pays to be a generalist. The beauty of looking for life in general is that you find things you weren’t expecting. We found our harvestmen but so much more as well.

Harvestman Nemastoma bimaculatum 

A suitable log: Oliver Salvers (Catinella olivacea) lurk beneath.

Notes

Note 1 – Catinella olivacea is on page 1450 of “Fungi of Temperate Europe” by Thomas Læssøe and Jens H Petersen (Princeton University Press, 2019). The book is in two volumes and contains over 7,000 photographs of more than 2,800 species of fungi. Its size and weight mean that it is definitely not a field guide, but is a useful reference book for use at home.

Catinella olivacea is also illustrated with other “discos and ascos” on page 317 of Sterry and Hughes’ book “Collins Complete British Mushrooms and Toadstools”. I’m not sure I would have recognised our specimens from the photo, however, because it shows a mass of older, darker specimens.

There are some good photos on the web. The MycoKey website has photos from England, Denmark and Germany and Mycoquebec.org website shows specimens from Quebec.

Kew’s Catalogue of Life website lists other synonyms for Catinella olivacea. One of these is Karschia olivacea.

Note 2 – I’ve written about several other fungi on this blog, including Dune Cup, Scarlet Elfcup, Alder Goblet and Spring Hazelcup.

Note 3 – This disperal of Catinella olivacea spores is described in “With a Little Help from Arthropods: Catinella olivacea” on Jan Thornhill’s Weird and Wonderful Wild Mushrooms blog and is referred to in the 2007 paper “Ascoma development and phylogeny of an apothecioid dothideomycete, Catinella olivacea” by M.D. Greif, C.F. Gibas, A. Tsuneda and R.S. Currah. (Am J. Bot.  Vol 94, pp1890-1899).

Note 4 – The holotype (the original type specimen upon which the description and name of the species is based) is held by the Meise Botanic Garden in Belgium and was found in the Belgian Congo in 1907. (As a strange coincidence I’ve just started reading “Blood River: A Journey to Africa’s Broken Heart” by Tim Butcher, a 2007 book describing a journey in the modern Democratic Republic of Congo.)

Note 5 – The cost of living crisis doesn’t help, either, as people gather up wood to burn. Our local cemetery is one just a few places in the British Isles where the harvestman Dicranopalpus larvatus can be found, usually under pieces of dead wood. Recently someone has been gathering rotten sticks and branches for firewood, inadvertently removing prime habitat for the species.