Endogone lactiflua is characterized by compact hypogeous fruiting bodies which could have different shapes: subglobose to ellipsoid and sometimes lobed and irregular or ovoid (Berch and Fortin 1984; Trappe and Gerdemann 1972; Gerdemann and Trappe 1974; Blaszkowski et al. 2004). Size ranges from 3 to 9 (-15) mm broad and usually having a basal attachment to the soil (Trappe and Gerdemann 1972; Gerdemann and Trappe 1974). Sporocarps collected in Japan forest had 3-16 mm in diameter, they pale yellow color, and without opening (Yamamoto et al 2015). Sporocap sizes of the Endogone species may depend on physical and chemical features of the soil where these fungi are found (Blaszkowski et al. 1998).
Young sporocarps are composed by a white, thin, and pubescent peridium (Blaszkowski et al. 2004; Gerdemann and Trappe 1974). Specimens collected from eastern Canada show peridiums 20-40 µm thick consisting of barely septate, branching and interwoven hyphae (Berch and Fortin 1984). Whereas, sporocarps collected in Japan had 40.7-54.5 µm in thickness (Yamamoto et al. 2015). With the age peridium is deteriorated, and partly or completely open, thus exposing hundreds of zygosporangia (Blaszkowski et al. 2004).
Gleba contains many zygosporangia and glebal hyphae densely packet. In young specimens gleba has yellow pale color, usually with a sterile base, and exudes sticky latex (Trappe and Gerdemann 1972; Gerdemann and Trappe 1974; Yamamoto et al. 2015). In sporocarps collected in Quebec, Canada, gleba presented hyphae with thick walls (Berch and Fortin 1984).
Individual or compact aggregates consisting of two Zygosporangia, enveloped by a hyphal mantle, are randomly arranged in the peridium, loose aggregates or single are rarely found in the soil (Blaszkowski et al. 2004). Mantle hyphae, 5-50 µm thick (Gerdemann and Trappe 1974) form a dense net of many interwoven, yellowish or clear (hyaline) and sometimes inflated hyphae layers. Mantle region adjacent to the zygosporangia is more compactly interwoven than outer part (Blaszkowski et al. 2004).
Distinct shapes of Zygosporangia including globose to subglobose (90-170 µm diameter), ovoid or broadly ellipsoidal (100x160 µm) and circular (13.5-15.0 µm diam.) or slightly ellipsoidal (8.8-16.3 µm) have been reported for E. lactiflua specimens from Poland (Blaszkowski et al. 2004). Zygosporangia bears a single, smooth wall layer, with 1.5-2.7 µm thick and melon yellow to dark orange color. Microscopic observation of zygosporangial wall in E. lactiflua for Poland reveals a complex structure composed for very thin and inseparable sublayers (Blaszkowski et al. 2004).
Zygosporangial wall gets easily separated, leaving a remaining body called zygospore. Zygospores could have globose to ellipsoid shapes with 71-180 x 94-190 µm size (Trappe and Gerdemann 1972). Zygospore wall (0.7-4.1µm thick) is colorless, semi-flexible, and thicker than Zygosporangial wall (Blaszkowski et al. 2004). However, zygospore walls with similar thickness or even lower than Zygosporangial wall may be observed on early developmental stages (Blaszkowski et al. 2004). Immature zygospores in a collection from eastern Canada presented thin wall with about 2 µm (Berch and Fortin 1983). Zygospores contain hyaline lipid globules (Blaszkowski et al. 2004)
Gametangia are also densely covered by mantle hyphae; therefore, it is sometimes difficult observed them. At maturity, gametangia persist and become thick-walled (Gerdemann and Trappe 1974; Blaszkowski et al. 2004). The larger gametangium (25-40µm wide) of the two concurring gametangia subtends the zygospores (Berch and Fortin 1984). Large gametangium usually has a thick wall (up to 3 µm)and is delimited by two septa. One is associated with a pore of the zygosporangium and the other one is associated with the smaller gametangium by an ephemeral suspensor, therefore the smaller gametangium has not acontact with the zygosporagium (Berch and Fortin 1984; Blaszkowski et al. 2004).
Endogone lactiflua Berk. & Broome 1846 is a small Zygomycetous truffle. Etymologically, its name, lacti- (milk) and -fluo (flowing), refers to the sticky and white latex exuded when fresh specimens are cut. E. lactiflua was first described by Berk and Broome in 1846. It belongs to the Endogone genus. The Endogone genus is part of the Endogonaceae family, within Zygomycetes phylum (Trappe and Gerdemann 1972; Gerdemann and Trappe 1974; Trappe et al. 2009; Walker 1985).
Fruiting bodies are found underground (hypogeous), containing single or aggregates of zygosporangia. Sexual spores are rarely found in the soil (Blaszkowski et al. 2004). Therefore, it is presumable that their dispersion depends on either movement of soil or on small animal mycophagists as vectors for spore dissemination (Maser et al. 1978).
Endogone lactiflua has probably a word wide distribution. It has bed reported for temperate regions in Europe, North America and Japan. It is commonly found in Coniferous and Quercus forest from the sea level to subalpine zones (Blaszkowski et al. 2004; Trappe and Gerdemann 1972; Gerdemann and Trappe 1974; Yamamoto et al. 2015). Ectomycorrhizal associations between E. lactiflua with several conifer species across diverse geographic regions have been reported (Fassi et al. 1969; Grubisha et al. 2003;).
Endogone lactiflua belongs to Endogone genus. The Endogone genus is part of the Endogonaceae family, within Zygomicetes phylum. E. lactiflua was first described by Berk and Broome in 1912. It has been confused with other species from the same genus including E. flammicorona, E. lanata, E. rosea and E. maritima (Berch and Fortin 1984; Trappe and Gerdemann 1972; Gerdemann and Trappe 1974). Comparisons between E. flammicorona and E. lactiflua performed by Trappe and Gerdemann (1972) allow their differentiation and a later description of E. flammicorona. The gametangia of E. lactiflua have thick walls and persist at maturity compared with gametangia of E. flammicorona, which have ephemeral, thin walls and they are not present at maturity (Berch and Fortin 1983; Blaszkowski et al. 2004). A phylogenetic analysis of the large subunit nuclear ribosomal RNA gen, using Japanese different specimens identified either as E. lactiflua or E. flammicorona base on their morphology, were separated in two completely distinct groups (Yamamoto et al. 2015). However, Desiro at el (2014) reported that Mre are present inside of the cytoplasm of 13 from 29 Endogone species and their 16S rRNA gene sequences cluster together E. flammicorona and E. lactiflua
Endogone lactiflua has a wide world distribution. It is commonly found in coniferous and Quercus forest from the sea level to subalpine zone. E. lactiflua has been usually reported for temperate regions in Europe and North America (Trappe and Gerdemann 1972). However, Yamamoto et al (2015) recently reported the first description for E. lactiflua using specimens from various forests located in warm temperatures to subalpine zones in Japan, Asia. Specimens were collected during spring through late autumn. In eastern North American and Europe, specimens are found from April to July and sometimes at late November (Gerdemann and Trappe 1974).
Endogone lactiflua were found in a sample collected from the upper soil layer up to the rhizosphere of Pinus sylvestris. The pines forest was located 500 m away from the bank of the Baltic Sea in the northern region of Poland (Blaszkowski et al. 2004). Berch and Fortin (1984) reported specimens of E. lactiflua growing below sphagnum on rocky slope with red maple (Acer rubrum L.) and white spruce (Picea glauca) in eastern Canada. Sporocarps of E. lactiflua have been observed in transplants of P. cordata in Newton Nursery, Morayshine, Scotland (Walker 1985) and in species of Pinus and Pseudorsuga menziesii in a nursery near to Prato Sesia, Piemonte, Italy (Fassi et al. 1969).
Spores of E. lactiflua were identified in rodent digestive tracts collected from various habitats within a coniferous forest from Oregon, USA (Maser et al. 1978). A preliminary record of ectomycorrhizal fungi in two California Channel Islands reported the presence of E. lactiflua in two northern islands: Santa Cruz and Santa Rosa which have Mediterranean weather (Grubisha et al 2003).
Endogone genus includes saprophytic, ectomycorrhizal associated with various woody plant species (Fassi et al. 1969; Walker 1985; Trappe et al. 2009), and vesicular-arbuscular (VA) endomycorrhizal species (Maser at al. 1978, Yamamato et al. 2015). Ectomycorrhizal associations between E. lactiflua with several conifer species across diverse geographic regions have been reported (Fassi et al. 1969; Walker 1985). Fruiting bodies of E. lactiflua were observed on and below the surface of peat, where pine (Pinus cordata) transplants were growing (Walker 1985). Lugol lactic blue methods showed ectomycorrhizal associations between E. lactiflua with 2 to 3 years-old plant species of Pinus and Pseudorsuga menziesii (Fassi et al. 1969).
Sporocarps of E. lactiflua may be an important diet component of a Pacific jumping mouse (Zapus trinotatus). Analyses of digestive tract from individuals collected in edges or shrub forbs in coniferous forests from Oregon showed that this small mammal prefers to consume E. lactiflua fruiting bodies over hypogeous Basidiomycetes and Ascomycetes occurring in the same area (Maser et al. 1978). E. lactiflua spores were also found in other rodent species such as Clethrionomys californicus californicus, Clethrionomys californicus mazana, Clethrionomys rutilus, and Peromyscus maniculatus. However, they did not show preference for some fungi over others (Maser et al. 1978).
