Species Fact Sheet
Scientific Name: Arrhenia lobata (Pers.) Kuhner & Lamoure ex Redhead (Synonyms = Cantharellus lobatus (Pers.) Fr., Corniola lobata (Pers.) Gray, Dictyolus lobatus (Pers.) Quel., Leptoglossum lobatum (Pers.) Ricken, Deptotus lobatus (Pers.) p. Karst., Merulius lobatus Pers.)
Technical Description (Gibson, 2007):
Cap 0.5-4 cm, rarely round, more often oboval, fan-shaped or kidney-shaped, rarely funnel-shaped, membranous, margins incurved and remaining so, usually lobed, sometimes deeply incised, sometimes crisped (finely wavy) and scalloped; hygrophanous, light gray brown to gray yellow brown or buff, fading when partially dry, often blackening on exposed margins or when dry; surface moist. Underside smooth when immature, soon with branched more or less radially arranged veins with numerous cruving anatomosing lateral veins or more irregularly veined-wrinkled, often forking; colored as cap or paler. Stem not well formed, atachment off-center or lateral, base may be whitish or just paler than cap, attached by whitish mycelium. Spores 5-10(15) x 4.2-8.5 um, more or less elliptic, smooth, inamyloid, colorless, with conspicuous blunt apiculus; clamp connections present.
In their combination of morphological features and habitat, relatively few other veined fungi are likely to be mistaken for Arrhenia lobata. The most conspicuous group of veined fungi - the chanterelles - which include the genera Cantharellus, Craterellus, Gomphus and Polyozellus, have upright sporocarps "with vein-like folds on the underside of a cap (usually running down onto the upper part of the stem) or on the outside of a funnel-like sporocarp, 5 cm or more tall when mature, generally growing on the ground" (Gibson, 2007). Besides Arrhenia, genera with at least some species with small sporocarps (< 5 cm) with vein- or gill-like spore-bearing structures are included in several genera including Cudonia, Marasmius, Mycena, Hemimycena, Rimbachia and Stereopsis. Within this group, only Cudonia circinans and several species of Arrhenia have sporocarps that are typically some color other than white. The cap of Cudonia circinans often includes some red or yellow pigmentation, resulting in colors such as pink, cinnamon, vinaceous or yellowish (although cream buff and pale brown colors are also described). The cap of Arrhenia species most frequently exhibits tones of gray and brown. The spores of Cudonia circinans are needle-like in shape, in contrast with the typically elliptic to oboval shapes of Arrhenia species. Among the several species of Arrhenia documented within the Pacific Northwest, the short or indistinct stalks and veined caps of A. lobata and A. retiruga are in contrast with the well-formed gills on mature caps in A. acerosa, and the distinct, upright stalks of A. spathulata. The oboval, fan-shaped or kidney-shaped caps of A. lobata distinguish it from the A. retiruga with its nearly round to bilaterally symmetric caps. An expanded generic concept for Arrhenia is provided by Redhead (1984).
Life History: Sporocarps of Arrhenia lobata are single or clustered at known sites. All species of Arrhenia are regarded as "bryophiles" (i.e., consistently associated with mosses) (Redhead, 1984) and a parasitic relationship between A. lobata and moss gametophytes has been suggested (Savile and Parmelee, 1964). On the Iberian Peninsula sporocarps of Arrhenia lobata are found on the moss genera Aulacomnium, Calliergonella, Drepanocladus and Sphagnum (Barrio et al., 1985; Ortega et al., 1997) - genera which are common in the fens of Pacific Northwest. In contrast, sporocarps of this fungus have never been found on Sphagnum in northern Europe (Hoiland, 1976; Hallgrimsson, 1981; Gulden, 1988). On the Iberian Peninsula, most sporocarps are found between April and August and may be primarily produced in spring (Barrasa and Rico, 2003).
Range, Distribution and Abundance: Arrhenia lobata is known from arctic and alpine areas and is primarily circumboreal in distribution but is also known from the Iberian Peninsula and central Europe as well as Australia. In North America, the species is known from Canada (primarily northern and eastern but one site in extreme northwest BC), Oregon (Wallowa Co.), Washington, Idaho and Colorado.
Habitat Associations: On moss in wet sites, alpine sites or bogs or fens, often around the margins of pools.
Threats: The mid- to higher elevation wetland/peatland sites occupied by Arrhenia lobata are susceptible to physical and chemical disturbances that promote successional processes with the possible resultant loss of rare or uncommon plant taxa. Livestock commonly damage or destroy wetland/peatland shrubs and herbaceous vegetation, reducing its annual primary productivity and reproductive success. Soil compaction caused by livestock has the potential to alter patterns and rates of local water movement while livestock feces may alter local water chemistry. Water diversions resulting from adjacent road construction, off-site diversions or impoundments for stock or agriculture, or on-site drainage efforts to improve forage for livestock, can lower local water tables. Additionally, habitats suitable for Arrhenia lobata may be susceptible to infestation by wetland invasives such as Phalaris arundinacea and Cirsium arvense.
Conservation Considerations: Revisit known sites to confirm persistence and better define the extent of populations. Conduct searches for new populations; include Arrhenia to list of target species when conducting basic inventories of wetlands/peatlands at mid- to higher elevations. At known sites or in potential habitat, manage weatland/peatland to maintain hydrologic regime. Identify opportunities for the inadvertent introduction of invasive plant species and develop preventative practices to minimize these risks. Develop a treatment plan for any invasive plant species already present.
Conservation Rankings and Status:
Global: G1; Oregon S1
ORNHIC List 3
Prepared by: Rick Dewey, Deschutes National Forest, April 2009
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