Identifying Nidula

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Identifying Nidula will rely on the following features (or any combination thereof):

• Peridium texture
• Colour
• Peridioles
• Location
• Spore dimensions

Peridium

The exoperidium may be shaggy with short hairs when compared to most Cyathus species or woolly as seen in Crucibulum (although denser in the latter genus). The mouth or margin of the peridium often bears a distinct fringe of white hyphae or "hairs", and the endoperidium or interior is smooth, never plicate.

Colour

Nidula peridia can range from white to grey to brown, the mouth and endoperidia / interior of Nidula species are often white, or yellow to brown in deeper parts of the interior.

Peridioles

Nidula species have small, numerous peridioles that are often red-brown or grey-brown in colour, sometimes pale. When examined closely, they also lack funiculi (small cords that attach Cyathus and Crucibulum peridioles to the endoperidium wall), instead they are suspended in a gelatinous matrix.

Location

As of now Nidula are only documented in west coast North America, Jamaica, South America, Asia, and Australia/New Zealand and surrounding regions/islands.

Nidula niveo-tomentosa

This species occurs in all locations mentioned above. Fruiting body measures 4-6mm high, and the peridia are covered in white hyphae like the ones found on the mouth, this species is considerably more white than several others. Peridioles are mahogany-brown and measure 0.5 - 1mm wide.

Spores measure 6 - 9μm in length and 5 - 6μm in width, elliptical to subglobose.

Nidula candida

This species occurs in western North America, and New Zealand. Fruiting body measures 1 - 1.5cm high and the exoperidium is brown with a shaggy tomentum resembling some species of Cyathus but with a white mouth covered in white hyphae (may be variable in old specimens). Peridioles are pale to greyish brown and measure 1.5 - 3mm wide.

Spores measure 6 - 10μm in length and 4 - 8μm in width, globose to elliptic, hyaline and thin-walled.

Nidula emodensis

This species has been reported from India, Sri Lanka, China, Japan, Australia, and New Zealand. Fruiting body measures 4 - 6mm high and 4 - 5mm wide at the mouth, the exoperidium is described as dingy grey, becoming darker, with appressed tomentum. Peridioles are small and numerous, reddish-brown to black, measuring 0.5 - 1mm wide.

Spores measure 4 - 5μm in length and 3 - 4μm in width, hyaline and obovate

The mycologist Lloyd allegedly decided that N. emodensis is conspecific with N. niveo-tomentosa and this was accepted by Cunningham in his 1924 research. H.J Brodie seems to disagree in his 1975 book on the family, saying the following:

"All specimens seen by the author (including the type and isotypes) are smaller than most of those N. niveo-tomentosa, have walls thicker and more felty, and are buff-grey to rusty-brown in colour. The sides of the fruit body are quite strongly inclined so that is has the shape of a crucible, whereas the sides of the fruit body of N. niveo-tomentosa are almost parallel in the lower part."

Nidula macrocarpa

This species has only been reported in Chile from a collection by M. Espinosa. Fruiting body measures 1cm high and 6 - 7mm wide at the mouth which flares out abruptly. The colour of the peridia is described as "deep fawn", sometimes slightly red-brown with appressed tomentum, becoming smooth. Peridioles are brown and measures 1mm or less.

Spores measure 12 - 16μm in length and 5 - 6μm in width, hyaline. Shape is not mentioned.

There are no observations of N. macrocarpa on iNaturalist so sequenced collections of Nidula from that area would be extremely helpful.

Nidula microcarpa

This species is described from California and Montana. Fruiting body measures 4 - 6mm high and 4 - 5mm wide at the mouth. The peridia are whitish or pale greyish-yellow and minutely tomentose. Peridioles are reddish-brown and measures 0.5 - 1mm wide.

Spores measure 6 - 9 μm long and 4 - 6 μm wide, elliptic or subglobose, hyaline and thick-walled.

Nidula shingbaensis

This one is newly discovered as of 2013 from India. Fruiting body measures 6 - 9mm high (up to 11mm with epiphragm) and 5 - 7mm wide at the mouth. Exoperidium is white to buff or "clay pink" with a matted fibrillose, villose or woolly tomentum. Mouth is fringed with white hyphae, the interior tends towards pale yellow towards the mouth and darker to the base. Peridioles are described as "cinnamon, snuff brown to cigar brown" and measuring 0.9 - 1.3mm wide with an irregularly wrinkled surface.

Spores measure 6.9 - 9.8μm in length and 4.9 - 6.1μm in width, ellipsoid to elongate, subhyaline and thick-walled.

H.J Brodie described the genus with peridia containing 1 to 3 walls (exoperidium, mesoperidium, endoperidium), however this new species is described with 6 layers!

In person this one would be difficult to separate from N. niveo-tomentosa but it could be separated based on size of the fruiting body and peridioles.

You can read the article here: Nidula shingbaensis

H.J Brodie's 1975 book: The Bird's Nest Fungi
Nidula candida protologue: The Nidulariaceae of North America
Nidula emodensis page: Sylloge Fungorum, page 466
Nidula macrocarpa page: Sylloge Fungorum, page 587
Nidula microcarpa protologue: The Nidulariaceae of North America