Archaeomarasmius

Archaeomarasmius; Temporal range: Turonian PreꞒ Ꞓ O S D C P T J K Pg N ↓
	Artist's reconstruction
Scientific classification
Kingdom:	Fungi
Division:	Basidiomycota
Class:	Agaricomycetes
Order:	Agaricales
Family:	Tricholomataceae
Genus:	† Archaeomarasmius ; Hibbett, Grimaldi & Donoghue
Species:	†A. leggetti
Binomial name
	†Archaeomarasmius leggetti; Hibbett, Grimaldi & Donoghue

Last updated January 31, 2023

Archaeomarasmius is an extinct genus of gilled fungus in the Agaricales family Tricholomataceae, containing the single species Archaeomarasmius leggetti. It is known from two fruit bodies recovered from amber, one consisting of a complete cap with a broken stem, the other consisting of a fragment of a cap. The cap has a diameter ranging from 3.2 to 6 mm (0.13 to 0.24 in), while the stem is 0.5 mm (0.02 in) thick. Spores were also recovered from the amber, and are broadly ellipsoid to egg-shaped, measuring roughly 7.3 by 4.7 μm. The species, which resembles the extant genera Marasmius and Marasmiellus , is inferred to have been saprobic on plant litter or other forest debris.

The genus is solely known from the New Jersey amber deposits along the Atlantic coastal plain in New Jersey, United States, which date from the Turonian stage (about 90–94 Mya) of the Upper Cretaceous.^[1]Archaeomarasmius is one of only five known agaric fungus species known in the fossil record, and the only one to be described from New Jersey amber.

History and classification

The genus is known only from the two holotype fossils, a fruit body (or mushroom) and a fragment of a mushroom, both currently residing in the American Museum of Natural History.^[1] The specimens, collected in November 1994 from the area of East Brunswick, New Jersey, by G.R. Case, P.D. Borodin, and J.J. Leggett, were found as a single clear yellow amber nodule 6 cm (2.4 in) in diameter. The specimen was found above the South Amboy Fire Clay, part of the Raritan Formation, suggesting that it is Turonian in age (Upper Cretaceous, about 90 to 94 million years ago). Due to weathering, the amber specimen AMNH NJ-90 fractured into a number of chips along fractures and flow lines. The chips with the holotype specimens, AMNH NJ-90Y and AMNH NJ-90Z, were first studied by a group of researchers consisting of David Hibbett and Michael Donoghue from Harvard University with David Grimaldi of the AMNH. Hibbett and colleagues published their 1997 type description in the American Journal of Botany .^[1] The generic epithet Archaeomarasmius is a combination of the Greek archaeo- meaning "ancient" and " Marasmius ", a modern genus which it resembles. The specific epithet "leggetti" was coined by the authors in honor of J.J. Leggett and company, who first discovered the amber nodule and donated it to the AMNH.^[1]

When first reported, Archaeomarasmius leggetti was the second extinct species of agaric fungus to be described, and it is the only species to be known from the New Jersey amber. Three species, Aureofungus yaniguaensis , Coprinites dominicana and Protomycena electra , have been described from the Miocene Dominican amber found in the Dominican Republic.^[1]^[2] The extinct Agaricomycetes species Quatsinoporites cranhamii , found in marine calcareous concretions on Vancouver Island, Canada, and dating to about 130–125 Mya, is probably in the Hymenochaetales or the Polyporales.^[3] In 2007, another agaric was reported, Palaeoagaracites antiquus , found in Early Cretaceous Burmese amber (about 100 Mya).^[4]

Description

Marasmius rotula (above) and Marasmiellus ramealis (below) are modern species that resemble Archaeomarasmius.

The holotypes of Archaeomarasmius consist of mushrooms and associated basidiospores. Specimen AMNH NJ-90Y is a nearly complete mushroom, broken off near the base of the stipe (stem). The pileus (cap) is up to 6 mm (0.24 in) in diameter and has a convex shape sporting an umbo (a broad raised central region). The mushroom is a medium-dark brown color with thin, minutely textured flesh and an incurved margin. The lamellae or gills are distantly spaced, with 12 gills extending fully from the cap edge to the stipe, and lack lamellulae (short gills which do not reach the stipe from the edge of the pileus). The pileus is centered on the stipe, which is 0.5 by 2.2 mm (0.020 by 0.087 in) long and is broken off above the base. The stipe lacks a veil and is smooth and cylindrical. The top of the pileus is exposed on a fracture plain, and to prevent oxidation, the area was coated in a fine layer of synthetic resin, which also resulted in slightly improved visibility of the mushroom.^[1]

Specimen AMNH NJ-90Z is a small wedge-shaped fragment of pileus which was accidentally fractured during preparation for study, splitting it in half. Though the researchers had not intended to perform destructive analysis on the sample, this fracturing warranted the sacrifice of some parts of the specimen for structural and molecular study. Small pieces of the specimen were mounted directly on scanning electron microscopy (SEM) stubs and sputter coated with a gold/palladium alloy. The resulting images showed that little intact tissue remained, and only fragmented and crushed basidiospores were seen. Another sample of the specimen was mounted in spurr's resin (an embedding medium used in electron microscopy) and sectioned with a diamond knife; the resulting sections were examined with transmission electron microscopy (TEM). The lack of discernible biological material from the mushroom seen in the SEM study was confirmed in the TEM analysis. A final section of the fossil was selected to attempt DNA sequencing. A small sample of the fossil was extracted at the AMNH and sent to the Peabody Museum of Archaeology and Ethnology for DNA amplification. None of the three selected extracts showed any results after the amplification was attempted. It is possible that the fractures and flowlines which split AMNH NJ-90Z during initial preparation had already penetrated into the fossil and destroyed the hermetic seal which would have been needed for preserving the organic matter of the mushroom.^[1]

The basidiospores recovered with the fruiting body were examined during the SEM study. The spores showed considerable damage from both the fossilization process and the subsequent weathering and specimen collection. They also displayed distinct halos in the amber, possibly from gas or liquid leaching out, or a reaction in the spores that prevented the resin from turning to amber. Even so, enough remained to make some observations about spore morphology. The basidiospores are broadly elliptic to oval, measuring approximately 7.3 by 4.7 μm, and each shows a distinct hilar appendage.^[1]

The combined characters of Archaeomarasmius indicate a relation to the modern family Tricholomataceae, with a close similarity to the genera Marasmius and Marasmiellus . Both genera are noted for marcescence, toughening and drying, rather than putrifying. This property would increase the chances of a mushroom becoming entombed in amber. However, a number of other species are also possible close relatives of Archaeomarasmius, mostly in Tricholomataceae, although some species in the family Strophariaceae are also marasmioid. The authors suggest it may also be appropriate to classify Archaeomarasmius more conservatively as incertae sedis (of uncertain placement) within the Tricholomatoceae, Agaricales, or Homobasidiomycetes.^[1]

Associated inclusions

The amber specimen "AMNH NJ-90", which preserved the two holotypes, also preserved a number of other inclusions that give indications as to what the ecology of Archaeomarasmius may have been. Of the approximately forty insect inclusions present, flies in the families Ceratopogonidae and Chironomidae, together with caddisflies of the order Trichoptera, suggest that the mushroom was growing near fresh water. Beetles from the family Elateridae, a termite and a pseudoscorpion, in addition to the mushroom, are indicators of rotting wood, probably from a tree in the family Cupressaceae. Modern Marasmiaceae members are saprobic—obtaining nutrients by breaking down organic matter—and specimens included with Archaeomarasmius indicate a similar habit for the mushroom.^[1]

Related Research Articles

The fungal order Agaricales, also known as gilled mushrooms or euagarics, contains some of the most familiar types of mushrooms. The order has 33 extant families, 413 genera, and over 13,000 described species, along with six extinct genera known only from the fossil record. They range from the ubiquitous common mushroom to the deadly destroying angel and the hallucinogenic fly agaric to the bioluminescent jack-o-lantern mushroom.

The Agaricaceae are a family of basidiomycete fungi and include the genus Agaricus, as well as basidiomycetes previously classified in the families Tulostomataceae, Lepiotaceae, and Lycoperdaceae.

The pileus is the technical name for the cap, or cap-like part, of a basidiocarp or ascocarp that supports a spore-bearing surface, the hymenium. The hymenium (hymenophore) may consist of lamellae, tubes, or teeth, on the underside of the pileus. A pileus is characteristic of agarics, boletes, some polypores, tooth fungi, and some ascomycetes.

The Tricholomataceae are a large family of mushrooms within the Agaricales. Originally a classic "wastebasket taxon", the family included any white-, yellow-, or pink-spored genera in the Agaricales not already classified as belonging to e.g. the Amanitaceae, Lepiotaceae, Hygrophoraceae, Pluteaceae, or Entolomataceae.

The evolution of fungi has been going on since fungi diverged from other life around 1.5 billion years ago, with the glomaleans branching from the "higher fungi" (dikaryans) at ~570 million years ago, according to DNA analysis. Fungi probably colonized the land during the Cambrian, over 500 million years ago,, and possibly 635 million years ago during the Ediacaran, but terrestrial fossils only become uncontroversial and common during the Devonian, 400 million years ago.

Melanoleuca is a poorly known genus of saprotrophic mushrooms traditionally classified in the family Tricholomataceae. Most are small to medium sized, white, brown, ocher or gray with a cylindrical to subcylindrical stipe and white to pale yellowish gills. The basidiospores are ellipsoid and ornamented with amyloid warts. Melanoleuca is considered a difficult group to study due to their macroscopic similarities among species and the need of a thorough microscopic analysis to separate species. DNA studies have determined that this genus is closely related to Amanita and Pluteus and that it does not belong to the family Tricholomataceae.

The Mycenaceae are a family of fungi in the order Agaricales. According to the Dictionary of the Fungi, the family contains 10 genera and 705 species. This is one of several families that were separated from the Tricholomataceae as a result of phylogenetic analyses. Taxa in the Mycenaceae are saprobic, have a cosmopolitan distribution, and are found in almost all ecological zones. The family was circumscribed by Caspar van Overeem in 1926.

Coprinites is an extinct monotypic genus of gilled fungus in the Agaricales family Agaricaceae. At present it contains the single species Coprinites dominicana.

Aureofungus is an extinct monotypic genus of gilled fungus in the order Agaricales. At present it contains the single species Aureofungus yaniguaensis.

Protomycena is an extinct monotypic genus of gilled fungus in the family Mycenaceae, of order Agaricales. At present it contains the single species Protomycena electra, known from a single specimen collected in an amber mine in the Cordillera Septentrional area of the Dominican Republic. The fruit body of the fungus has a convex cap that is 5 mm (0.2 in) in diameter, with distantly spaced gills on the underside. The curved stipe is smooth and cylindrical, measuring 0.75 mm (0.030 in) thick by 10 mm (0.39 in) long, and lacks a ring. It resembles extant species of the genus Mycena. Protomycena is one of only five known agaric fungus species known in the fossil record and the second to be described from Dominican amber.

Palaeoagaracites is an extinct monotypic genus of gilled fungus in the order Agaricales. It contains the single species Palaeoagaracites antiquus.

Mycetophagites is an extinct fungal genus of mycoparasitic in the order Hypocreales. A monotypic genus, it contains the single species Mycetophagites atrebora.

Entropezites is an extinct monotypic genus of [hypermycoparasitic] fungus in the order Hypocreales. At present it contains the single species Entropezites patricii.

Plumalexius is a genus of wasps in the extinct monotypic family Plumalexiidae, containing two species: the type species Plumalexius rasnitsyni, known from the Late Cretaceous White Oaks Pit in Sayreville, New Jersey, and Plumalexius ohmkuhnlei, known from the Cretaceous Burmese amber.

Marasmius koae is a species of agaric fungus in the family Marasmiaceae. Newly described to science in 2011, it is known only from Hawaiian montane wet forests. It produces small stemless fruit bodies that grow on the rotting wood of the flowering tree koa.

Volvopluteus michiganensis is a species of mushroom in the family Pluteaceae. It was originally described under the name Pluteus michiganensis but molecular studies have placed it in the Volvopluteus, a genus described in 2011. The cap of this mushroom is about 7–9 cm (2.8–3.5 in) in diameter, gray, and has a cracked margin that is sticky when fresh. The gills start out as white but they soon turn pink. The stipe is white and has a volva at the base. Microscopical features and DNA sequence data are of great importance for separating this taxon from related species. V. michiganensis is a saprotrophic fungus that was originally described as growing on sawdust. It has only been reported from Michigan (USA) and the Dominican Republic.

Volvopluteus asiaticus is a species of mushroom in the Pluteaceae family. The cap of this mushroom is about 70–90 mm (2.8–3.5 in) in diameter, greyish brown to brown. The gills start out white but they soon turn pink. The stipe is white and has a volva at the base. Microscopical features and DNA sequence data are of great importance for separating this taxon from related species. V. asiaticus is a saprotrophic fungus that was originally described as growing on the ground, in the humus layer. It is only known from Hokkaido (Japan).

Brownimecia is an extinct genus of ants, the only genus in the tribe Brownimeciini and subfamily Brownimeciinae of the Formicidae. Fossils of the single identified species, Brownimecia clavata, are known from the Middle Cretaceous of North America. The genus is one of several ants described from Middle Cretaceous ambers of New Jersey. Brownimecia was initially placed in the subfamily Ponerinae, until it was transferred to its own subfamily in 2003; it can be distinguished from other ants due to its unusual sickle-like mandibles and other morphological features that makes this ant unique among the Formicidae. The ant is also small, measuring 3.43 millimetres (0.135 in), and a stinger is present in almost all of the specimens collected. The morphology of the mandibles suggest a high level of feeding specialization.

Marasmius tageticolor is a species of agaric fungus in the family Marasmiaceae. Its fruit bodies have striped red and white caps. It is found in Mexico, Central America, and South America, where it grows on twigs.

Pseudotricholoma metapodium is a species of agaric in the family Tricholomataceae. It has been given the recommended English name of mealy meadowcap. The species has a European distribution, occurring mainly in agriculturally unimproved grassland. Threats to its habitat have resulted in the mealy meadowcap being assessed as globally "endangered" on the IUCN Red List of Threatened Species.

References

1 2 3 4 5 6 7 8 9 10 Hibbett DS, Grimaldi DS, Donoghue MJ (1997). "Fossil mushrooms from Miocene and Cretaceous ambers and the evolution of Homobasidiomycetes". American Journal of Botany. 84 (8): 981–991. doi: 10.2307/2446289 . JSTOR 2446289.
↑ Hibbett DS, Grimaldi D, Donoghue MJ (2003). "Another Fossil Agaric from Dominican Amber". Mycologia. 95 (4): 685–687. doi:10.2307/3761943. JSTOR 3761943. PMID 21148976.(subscription required)
↑ Smith SY, Currah RS, Stockey RA (2004). "Cretaceous and Eocene poroid hymenophores from Vancouver Island, British Columbia". Mycologia. 96 (1): 180–186. doi:10.2307/3762001. JSTOR 3762001. PMID 21148842.
↑ Poinar GO Jr; Buckley R. (2007). "Evidence of mycoparasitism and hypermycoparasitism in Early Cretaceous amber". Mycological Research. 111 (4): 503–506. doi:10.1016/j.mycres.2007.02.004. PMID 17512712.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[Hibbett_et_al_1997-1] 1 2 3 4 5 6 7 8 9 10 Hibbett DS, Grimaldi DS, Donoghue MJ (1997). "Fossil mushrooms from Miocene and Cretaceous ambers and the evolution of Homobasidiomycetes". American Journal of Botany. 84 (8): 981–991. doi: 10.2307/2446289 . JSTOR 2446289.

[Hibbett_et_al_2003-2] Hibbett DS, Grimaldi D, Donoghue MJ (2003). "Another Fossil Agaric from Dominican Amber". Mycologia. 95 (4): 685–687. doi:10.2307/3761943. JSTOR 3761943. PMID 21148976.(subscription required)

[Smith2004-3] Smith SY, Currah RS, Stockey RA (2004). "Cretaceous and Eocene poroid hymenophores from Vancouver Island, British Columbia". Mycologia. 96 (1): 180–186. doi:10.2307/3762001. JSTOR 3762001. PMID 21148842.

[Poinar2007-4] Poinar GO Jr; Buckley R. (2007). "Evidence of mycoparasitism and hypermycoparasitism in Early Cretaceous amber". Mycological Research. 111 (4): 503–506. doi:10.1016/j.mycres.2007.02.004. PMID 17512712.

[1]

[2]

[3]

[4]