''Protomycena'' is an extinct

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of gilled

fungus A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from t ...

in the family Mycenaceae, of order Agaricales. At present it contains the single

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

''Protomycena electra'', known from a single specimen collected in an

amber Amber is fossilized tree resin that has been appreciated for its color and natural beauty since Neolithic times. Much valued from antiquity to the present as a gemstone, amber is made into a variety of decorative objects."Amber" (2004). In ...

mine in the

Cordillera Septentrional The Cordillera Septentrional is a mountain range that runs parallel to the north coast of the Dominican Republic, with extensions to the northwest as Tortuga (Haiti), Tortuga island in Haiti, and to the southeast through lowlands to where it rises ...

area of the

Dominican Republic The Dominican Republic ( ; es, República Dominicana, ) is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean region. It occupies the eastern five-eighths of the island, which it shares with ...

. The

fruit body In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

of the fungus has a convex

cap A cap is a flat headgear, usually with a visor. Caps have crowns that fit very close to the head. They made their first appearance as early as 3200 BC. Caps typically have a visor, or no brim at all. They are popular in casual and informal se ...

that is in diameter, with distantly spaced

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

on the underside. The curved stipe is smooth and cylindrical, measuring thick by long, and lacks a

ring Ring may refer to: * Ring (jewellery), a round band, usually made of metal, worn as ornamental jewelry * To make a sound with a bell, and the sound made by a bell :(hence) to initiate a telephone connection Arts, entertainment and media Film and ...

. It resembles extant (currently living) species of the genus ''

Mycena ''Mycena'' is a large genus of small saprotrophic mushrooms that are rarely more than a few centimeters in width. They are characterized by a white spore print, a small conical or bell-shaped cap, and a thin fragile stem. Most are gray or br ...

''. ''Protomycena'' is one of only five known agaric fungus species known in the fossil record and the second to be described from Dominican amber.

Discovery and classification

The genus is known only from the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

specimen, a single

(

mushroom A mushroom or toadstool is the fleshy, spore-bearing fruiting body of a fungus, typically produced above ground, on soil, or on its food source. ''Toadstool'' generally denotes one poisonous to humans. The standard for the name "mushroom" is ...

) currently residing in the private collection owned by Ettore Morone of

Turin, Italy Turin ( , Piedmontese: ; it, Torino ) is a city and an important business and cultural centre in Northern Italy. It is the capital city of Piedmont and of the Metropolitan City of Turin, and was the first Italian capital from 1861 to 1865. T ...

. The specimen was collected in one of the amber mines in the

area of the island of Hispaniola, in the

. The amber is believed to date from the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

Burdigalian The Burdigalian is, in the geologic timescale, an age or stage in the early Miocene. It spans the time between 20.43 ± 0.05 Ma and 15.97 ± 0.05 Ma (million years ago). Preceded by the Aquitanian, the Burdigalian was the first and longest w ...

stage, about 20 to 16 million years before the present. It was first studied by a group of researchers consisting of

David Hibbett David Hibbett is an associate professor in biology at Clark University. He is considered one of today's leading researchers "in the analysis of fungal relationships through DNA analysis." At Clark he concentrates his lab work in evolutionary biolo ...

and Michael Donoghue from

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of high ...

, with David Grimaldi of the American Museum of Natural History. Hibbett and colleagues published their 1997

type description A species description is a formal description of a newly discovered species, usually in the form of a scientific paper. Its purpose is to give a clear description of a new species of organism and explain how it differs from species that have be ...

in the ''

American Journal of Botany The ''American Journal of Botany'' is a monthly peer-reviewed scientific journal which covers all aspects of plant biology. It has been published by the Botanical Society of America since 1914. The journal has an impact factor of 3.038, as of 2019 ...

''. The generic name ''Protomycena'' is noted as "first", and "''

''", a modern genus that it resembles. The specific epithet ''electra'' was coined by the authors from the Latin or Greek word for "amber", in reference to the mode of preservation. When it was reported, ''Protomycena electra'' was the third species of fossil agaric fungus to be described. The two species '' Coprinites dominicana'' and '' Aureofungus yaniguaensis'' are also known from the amber mines of the Dominican Republic, while the fourth species '' Archaeomarasmius leggeti'' is from the older,

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

age

New Jersey Amber New Jersey Amber, sometimes called Raritan amber, is amber found in the Raritan and Magothy Formations of the Central Atlantic (Eastern) coast of the United States. It is dated to the Late Cretaceous, Turonian age, based on pollen analysis of t ...

. With the 2007 publication of a fifth extinct agaric species, '' Palaeoagaracites antiquus'', the minimum age for the order Agaricales was pushed back to the

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± 0 ...

(approximately 100 Ma).

Description

The holotype of ''Protomycena'' is a single fruit body without any associated structures, preserved in a piece of clear light yellow polished amber approximately wide. The pileus is in diameter and has a convex shape, sporting a raised central region (an umbo). The pale

flesh Flesh is any aggregation of soft tissues of an organism. Various multicellular organisms have soft tissues that may be called "flesh". In mammals, including humans, ''flesh'' encompasses muscles, fats and other loose connective tissues, but ...

appears yellowish in the amber, and is smooth and glossy, changing to striate and slightly translucent towards the margin. The pileus margin is striated and slightly flared. The

on the underside of the pileus are broadly attached (

adnate Adnate may refer to: * Adnation, in botany, the fusion of two or more whorls of a flower * Adnate, in mycology, a classification of lamellae (gills) * Conjoined twins Conjoined twins – sometimes popularly referred to as Siamese twins – are ...

) to the top of the stipe, and distantly spaced—between six and eight gills extend completely from the pileus margin to the stipe. These full-length gills are anastomosed with lamellulae (short gills which do not reach the edge of the stipe from the pileus margin) of varying lengths. The pileus is centered on the curved stipe, which is smooth and cylindrical, measuring thick by long. The stipe lacks a

and

rhizoids Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be uni ...

. The mushroom is preserved with a small liquid and gas-filled bubble, possibly originating from the mushroom itself, which indicates the amber to be very solid and well-sealed. In Hibbett and colleagues' 1997 publication, ''Protomycena'' was placed in the subfamily ''Myceneae'', which at the time was considered part of the family

Tricholomataceae 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. th ...

; ''Mycena'' is currently classified in the family Mycenaceae. The placement was based solely on the visible structures, or macromorphology of the fruit body. Many of the features which are typically used to classify species into fungal

families Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Ideal ...

and subfamilies are based on microscopic features not visible or preserved in the amber specimen. Consequently, the assignment to ''Mycena'' is provisional (the authors also note certain similarities with extant members of ''

Marasmius ''Marasmius'' is a genus of mushroom-forming fungi in the family Marasmiaceae. It contains about 500 species of agarics, of which a few, such as '' Marasmius oreades'', are edible. However, most members of this genus are small, unimpressive ...

''), and the describing authors leave open the option of treating the genus placement as ''

incertae sedis ' () or ''problematica'' is a term used for a taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertain ...

'' (uncertain placement) within the Agaricales. ''Protomycena'' is distinct from other amber-preserved mushroom taxa such as '' Coprinites'', in the grooved surface of its pileus and its

anastomosing An anastomosis (, plural anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal ...

gills.

References

External links

Botanical Society of America
Image of amber specimen {{Taxonbar, from=Q1939683 †Protomycena †Protomycena Prehistoric fungi Natural history of Hispaniola Fossil taxa described in 1997 Miocene life Natural history of the Dominican Republic Neogene fungi Monotypic Agaricales genera