Summary:
The Alpova diplophloeus group is distinguished by a nearly spherical to ovoid fruitbody, surface yellowish brown to reddish brown, often deep reddish brown when bruised or exposed to air, a spore mass that is brown to reddish brown, darkening with age or exposure, and consists of small gel-filled chambers and whitish veins, and underground growth with a preference for alder. There are distinctive microscopic characters as well, including spores that are amyloid when young and inamyloid when mature, 6-spored to 8-spored basidia, and a distinctive peridial layer differing with species, with clamp connections - rare dermatocystidia may be present in A. concolor. Hayward(1), italicizing Latin, said of Alpova concolor, "Distinguished from other Alpova sp. by the combination of a structurally well differentiated two-layered peridium and the presence of dermatocystidia." |The Alpova diplophloeus group consists of at least three species according to Hayward(1) who used a combination of molecular and morphological characters. The holotypes of two of these are from the Pacific Northwest: Alpova diplophloeus from Friday Harbour WA, and Alpova concolor from Siuslaw National Forest OR (with supporting material from Maple Ridge, BC). Hayward(1) say of Alpova concolor (with Latin name italicized) "The structurally distinct two-layered peridium and existence in the Pacific Northwest of the United States causes us to suspect that Zeller and Dodge included this species in their concept of Alpova diplophloeus even though the holotype of Alpova diplophloeus does not belong to this species. At least among surveys that have deposited sequences in international sequence repositories, this species appears to be more common than A. diplophloeus". A third species, Alpova cinnamomeus (synonym Rhizopogon parvisporus) was described from Michigan and occurs also at least in Newfoundland-Labrador. |The three species can be differentiated as follows. Alpova diplophloeus has a structurally single-layered peridium, and spores more than 2.2 microns wide, whereas the other two have two structurally distinct layers and spores on average less than 2.2 microns wide. In Alpova cinnamomeus, the peridium separates easily from the gleba (spore mass), and the peridia cells collapse fully on drying, whereas in Alpova concolor the peridium is not easily separable and the peridial cells do not collapse fully on drying. The characters of Alpova diplophloeus include 1) a poorly differentiated peridium with variation in the peridium only in pigmentation (darker near surface of fruitbody), 2) wide spores (some more than 3.5 microns at widest point) with 1 or very rarely 2 droplets, and 3) an association with Alnus rubra, A. incana, and A. rhombifolia. The characters of Alpova concolor include 1) a 2-layered peridium, 2) dermatocystidia (rare), 3) spores with 2-droplets, and 4) an association with Alnus rubra and A. rhombifolia. The characters of Alpova cinnamomeus include 1) a peridium reviving poorly and easily separated from the spore mass when revived, 2) relatively large gleba chambers with large buffer cells, 3) frequently 2 droplets in spores, and 4) an association with A. alnobetula and perhaps others. |The Alpova diplophloeus group are abundant among false truffles in the Pacific Northwest (Trappe(13)).

Chemical Reactions:
FeSO4 on sections of dried material dark green on both spore mass and peridium; "KOH giving a reddish pigment diffusing from the peridium into the mounting medium but the peridium itself soon rusty brown in sections", (Smith(30))

Interior:
sticky-gelatinous; "chamber contents pale yellow to olive when young, soon discoloring to reddish brown or orange brown when exposed, near maturity brownish orange to reddish brown", (Smith(4)), |"composed of small chambers separated by pale yellow or whitish veins; chambers 0.05-0.3cm broad, filled with a gelatinous substance, pallid to pale yellowish or olive when young, becoming orange-brown to reddish-brown to dark vinaceous-brown at maturity," reminiscent of red gravel, (Arora), |mottled to virgate and with irregular cavities, at maturity filled with spores; when dry near russet and the consistency bone hard, (Smith(30)), |sticky-gelatinous, with gel-filled chambers 0.05-0.3cm broad separated by pale yellow veins; chamber contents when young "pale yellow to olive but soon discoloring to reddish brown or orange brown when exposed", "near maturity brownish orange to reddish brown and darkening only slightly or not at all when exposed, when dried yellowish brown to brownish black", (Trappe(11)), |glebal chambers burnt umber, "darkening slightly with exposure to air", stroma offwhite, "darkening with exposure to air to burnt sienna", (selected from Hayward(1) for Alpova concolor), |gleba chambers "cinnamon but darkening at maturity", embedded in off-white stroma, "producing a marbled appearance, the contents darkening when exposed and drying dark brown to black",(selected from Hayward(1) for Alpova diplophloeus)

Odor:
fruity at maturity (Trappe(11), Smith(4)), usually fruity at maturity (Arora)

Microscopic:
spores 4-5.5(6) x (1.8)2.2-2.8 microns, elliptic to oblong, (Smith(4)), spores 4.5-5.5 x 2.3-2.8 microns, elliptic, oblong, or in some cases allantoid in one view, or with slightly lateral protrusion causing the spore to be slightly angular, colorless in KOH singly but in masses pinkish buff, amyloid when young but inamyloid (yellow brown) when mature, basal scar inconspicuous; basidia 6-spored to 8-spored, 10-16 x 4-5 microns; tramal plates of interwoven colorless nongelatinous hyphae 2-6 microns wide; peridium a trichodermium of hyphae with rusty-fulvous walls mostly thickened somewhat, the cells in the layer up to 25 microns wide and about isodiametric to elongated, the layer appearing cellular as a result, at the outer surface the hyphal ends more or less projecting or the tips crooked and coiled around each other, septate, the cells many odd shapes and smooth-walled; clamp connections present on colored hyphae of peridium; all tissues inamyloid, (Smith(30)), spores elongate, smooth, thin-walled, colorless to pale brownish, (Trudell), spores 4-6 x 1.5-3 microns (Arora), spores for A. diplophloeus (minimum/first quartile/mean/third quartile/maximum) (4.0)5.2-5.70-6.0(7.0) x (2.0)2.1-2.45-2.5(3.0) microns, oblong to broadly allantoid, thick-walled, smooth, with 1 or very rarely 2 oil droplets, in Melzer''s reagent empire yellow to buff in mass, (Hayward(1)), spores for Alpova concolor (4.0)5.0-5.40-6.05[sic](6.0) x (1.5)2.0-2.1-2.1(3.0) microns, oblong to allantoid, thin-walled, 2 droplets when suspended in 3% KOH, empire yellow to buff yellow in mass in Melzer''s reagent, (Hayward(1)), spores for Alpova cinnamomeus (4.0)5.0-5.10-5.15(7.0) x (1.8)2.0-2.12-2.17(3.0) microns, oblong to allantoid, thin-walled, smooth, typically with 2 droplets in KOH but some spores with 1 or 3 oil droplets, empire yellow to buff yellow in mass in Melzer''s reagent, (Hayward(1))

Notes:
The Alpova diplophloeus group occur along Pacific Coast from CA to AK, and also known from moist habitats in Rocky Mountains, MI, NT, and NF, (Smith(4)). Collections were examined from BC, WA, OR, NF, NWT, AK, CA, CO, MI, UT, and WY, (Trappe(11)). The group are abundant in the Pacific Northwest, found from BC south to northern CA and east to the east coast, also in Europe, (Trappe(13)). They are frequent on foray lists for BC and collections from BC are at Pacific Forestry Centre and the University of British Columbia.