Morchella tridentina

Morchella tridentina was first described by Giacomo Bresadola in 1892 in a work on fungi found in the region of Trento in Italy.[3][4] The species' epithet derives from the Roman name of Trento,Tridentum, a tribute to the Roman god Neptune.[5]

In 1985, French mycologist Émile Jaquetant described the same species as M. elatoides,[6] a name that was later shown to be an invalidly published synonym of M. tridentina.[1]

In a 2012 publication by Michael Kuo and colleagues,[7] the taxon Morchella frustrata was described as new to science from Placer County, California, to accommodate the phylogenetic lineage defined the year before by DNA sequencing as "Mel-2".[8] The publication resulted from the Morel Data Collection Project,[9] which aimed to clarify aspects of the biology, taxonomy and distribution of North American Morchella, and described 14 new morel species without, however, ruling out existing European names.[2] As a result, in two subsequent international studies, Richard and colleagues (in 2014)[1] and Loizides and colleagues (in 2015)[2] used DNA analysis from both European and North American collections to determine that this species is identical to morels collected in southern Europe, matching the original 1892 description of Morchella tridentina by Bresadola. Two original collections identified as M. tridentina by Bresadola himself kept at the Swedish Museum of Natural History, were also studied and found to match the protologue and typical morphology of this species, although attempts to sequence these collections failed. Morchella frustrata was therefore placed in synonymy with M. tridentina, with the latter name having chronological priority over the former.[1]

Original illustration of Morchella tridentina by Giacomo Bresadola.

Morchella quercus-ilicis, proposed by Clowez in 2012[10] from collections in Huelva, Spain, was also shown by Loizides and colleagues to be a synonym of M. tridentina, as are the varieties Morchella conica var. pseudoeximia, and Morchella elatoides var. elegans.[2]

The first sequences of Morchella tridentina were published by Taşkın and collaborators in 2010, in a study investigating Morchella diversity in the Mediterranean and Aegean regions of Turkey. Because many morel lineages could not be ascribed with certainty to available binomials in early phylogenetic studies, this species was provisionally assigned the phylogenetic code "Mel-2".[12] Despite its pale colors, M. tridentina belongs to the /Elata clade (section Distantes) along with other black morels such as M. angusticeps, M. exuberans and M. importuna.[8][7] Together with the North American endemic M. tomentosa, M. tridentina occupies a basal position in the /Elata clade, which means it is adjacent to the root of the phylogenetic tree and therefore diverged earlier than other species in this clade.[13][1][2][14]

A 2017 study by Du and colleagues investigated the reproductive modes, mating type and life cycle of fourteen morel species including M. tridentina. The authors reported that all studied morels are heterothallic and their life cycles are predominantly haploid, although sterile haploid fruiting was also observed. Ascospores are mostly haploid, homokaryotic and multinuclear.[15]

Like all morels, Morchella tridentina is edible and choice. However, morels should not be eaten raw, as they can trigger allergic reactions in susceptible individuals. Their flavor is enhanced after they are fried, stuffed, or dried, and so is their safety for eating.[19][20]

Confusion with toxic species of genus Gyromitra, particularly G. esculenta, is rare but not unheard of.[20]

Global distribution map of M. tridentina (blackened regions) based on sequenced collections. Insert: Mediterranean collections.

Morchella tridentina has a widespread but disjunct distribution. So far, its presence has been molecularly verified in Argentina,[21] Armenia,[22] Chile,[17] Cyprus,[2] France,[1] India,[23] Israel,[22] North America,[8] Spain[1] and Turkey.[12] Kuo suggests that it might be also widely distributed in western North America, but so far it has only been confirmed to be present in Oregon and California.[18]

It is usually found in mountainous forests and Mediterranean shrubland, growing solitary, scattered, or in small groups in the spring. Its exact trophic mode is not yet known with certainty, but it is suspected to be facultatively biotrophic and may form endosymbiotic associations with a wide array of trees and shrubs.[24][25] Tree species associated with the fungus in North America include pacific madrone (Arbutus menziesii), oaks (Quercus spp.), Douglas fir (Pseudotsuga menziesii), ponderosa pine (Pinus ponderosa), sugar pine (Pinus lambertiana), and white fir (Abies concolor).[7] In Europe it is often found with holm oak (Quercus ilex), strawberry trees (Arbutus andrachne), olive trees (Olea europaea), Spanish fir (Abies pinsapo), Silver fir (Abies alba), Calabrian pine (Pinus brutia), and Scot's pine (P. sylvestris).[2][24]

Although it was initially hypothesised that collections of M. tridentina from Turkey might have been antrhopogenically introduced from the Pacific Northwest of North America,[26] numerous collections reported since from remote and undisturbed areas in the Mediterranean and the Alps (including Bresadola's original collection from Trentino), suggest a long-time and well-established presence of this species in Europe.[2][27] According to a 2021 study by Loizides and colleagues revising the evolutionary history of Morchella, this species is more likely to be a climatic relict, whose once wider distribution probably became fragmented during the Quaternary glaciations.[25]

• Media related to Morchella tridentina at Wikimedia Commons
• Morchella tridentina in Index Fungorum
• Morchella tridentina in MycoBank.
• Morchella tridentina in Ascomycete.org