Suillus bovinus, also known as the Jersey cow mushroom or bovine bolete, is a pored mushroom of the genus Suillus in the family Suillaceae. It was initially described as Boletus bovinus by Carl Linnaeus in 1753, and given its current binomial name by Henri François Anne de Roussel in 1806. Suillus bovinus produces spore-bearing fruit bodies, often in large numbers, above ground. The mushroom has a convex grey-yellow or ochre cap reaching up to 10 cm (4 in) in diameter, which flattens with age. Like other boletes, it has tubes extending downward from the underside of the cap, rather than gills; spores escape at maturity through the tube openings, or pores. The pore surface is yellow. The stipe, more slender than those of other Suillus boletes, lacks a ring. A common fungus native to Eurasia, it has been introduced to North America and Australia. The fungus grows in coniferous forests in its native range, and pine plantations in countries where it has become naturalised. It forms symbiotic ectomycorrhizal associations with living trees by enveloping the tree's underground roots with sheaths of fungal tissue, and is sometimes parasitised by the related mushroom Gomphidius roseus. Suillus bovinus is edible, but not highly regarded.
Taxonomy Suillus bovinus was one of the many species first described in 1753 by the "father of taxonomy" Carl Linnaeus, who, in the second volume of his Species Plantarum, gave it the name Boletus bovinus. The specific epithet is derived from the Latin word bos, meaning "cattle". The fungus was reclassified in (and became the type species of) the genus Suillus by French naturalist Henri François Anne de Roussel in 1796. Suillus is an ancient term for fungi, and is derived from the word "swine". Lucien Quélet classified it as Viscipellis bovina in 1886. In works published before 1987, the species was written fully as Suillus bovinus (L.:Fr.) Kuntze, as the description by Linnaeus had been name sanctioned in 1821 by the "father of mycology", Swedish naturalist Elias Magnus Fries. The description starting date for all the mycota had been set by general agreement as 1 January 1821, the date of Fries's work. Furthermore, as Roussel's description of Suillus predated this as well, the authority for the genus was assigned to Otto Kuntze. The 1987 edition of the International Code of Botanical Nomenclature changed the rules on the starting date and primary work for names of fungi, and names can now be considered valid as far back as 1 May 1753, the date of publication of Linnaeus's work. Common names include Jersey cow mushroom, bovine bolete, and euro cow bolete. One proposed origin for the scientific name is that medieval knights—who revered Tricholoma equestre—considered this mushroom fit only for cattle-drovers as it was not highly valued. The mushroom's colour is similar to that of a Jersey cow. A limited genetic sampling of species in a 1996 study by Annette Kretzer and colleagues showed Suillus bovinus was related to a lineage that diverged to S. punctipes, S. variegatus and S. tomentosus. A 2001 study found it was not closely related to other European species, and that all populations tested were closer to each other than any other and hence it was a cohesive species. Czech mycologist Josef Šutara circumscribed the genus Mariaella in 1987, assigning Mariaella bovina as the type species. Mariaella contained Suillus species in section Fungosi. Molecular studies do not support the existence of Mariaella, and so it is considered synonymous with Suillus. Older synonyms for S. bovinus include those resulting from generic transfers to Agaricus by Jean-Baptiste Lamarck in 1783, and the now-obsolete Ixocomus by Lucien Quélet in 1888. In 1951, Arthur Anselm Pearson described the variety Boletus bovinus var. viridocaerulescens, which was later transferred to Suillus by Rolf Singer in 1961. This variant, collected in Western Cape Province, South Africa, differs from the main form by the staining reaction of the cap flesh, which turns dark or light greenish-blue upon injury. Index Fungorum does not, however, recognize the variety as having independent taxonomic significance. Chemical analysis of pigments and chromogens showed that Suillus was more closely related to Gomphidius and Rhizopogon than to other boletes, and hence Suillus bovinus and its allies were transferred from the Boletaceae to the newly circumscribed family Suillaceae in 1997. Molecular studies have reinforced how distantly related these fungi are from Boletus edulis and its allies.
Description
The fruit body—colloquially called a mushroom—of Suillus bovinus is a basidiocarp which is smaller and daintier than most other boletes. The cap is initially convex, then flat with a wavy margin and a grey-yellow or ochre with pink tinge in some specimens. It ranges from 3–10 cm (1+1⁄4–4 in) in diameter and has a sticky skin. The flesh is whitish, yellowish or clay-coloured and has a fruity smell. Sometimes turning a pink tinge when bruised, the flesh is spongy and rubbery. Like other boletes, it has pores instead of gills that make up the hymenophore on the underside of the cap. Suillus bovinus has a characteristic compound pore layer, consisting of an outer layer of coarse, angular pores overlaying an inner layer of finer pores. The pores are grey- to olive-yellow and generally decurrent, comprising yellow to olive-yellow tubes that measure 0.3–1 cm (1⁄8–3⁄8 in) long. The stipe is 4–6 cm (1+1⁄2–2+1⁄4 in) tall, similar in colour to the cap, and tends to be narrower towards the base. With a diameter of 0.5–0.8 cm (1⁄4–3⁄8 in), it is more slender than those of other boletes.
The spore print is an olive-brown colour. The oval to spindle-shaped spores have dimensions of 8–10 by 3.5–4.5 μm. Basidia (spore-bearing cells) are cylindrical to narrowly club-shaped, measuring 22.4–33.4 by 5.8–8.0 μm. They bear four sterigmata (each holding a single spore), which are up to 6.8 μm long. Cystidia are present on both the tube ends (cheilocystidia) and tube faces (pleurocystidia). There are no clamp connections in the hyphae of Suillus bovinus. The cap cuticle comprises filamentous, gelatinized hyphae with a diameter of 2.6–5.0 μm. The mycelium has a pink tinge. The distinctive colour of the cap and pores make it hard to confuse with other species. Often found in similar habitats is S. variegatus, though this species has a granular cap and dark olive pores, which are smaller and not decurrent. It can also bruise blue.
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