Full name: Hebeloma longicaudum (Pers.) P. Kumm. (1871)
Published: Der Führer in die Pilzkunde: 80 (1871)
Taxonomic status: This is a Hebeloma but we have not been able to unambiguously determine the species.
Basionym: Agaricus longicaudus Pers. (1801): Fr. (1821)

Types: Not designated. There is no original or authentic material in Persoon's herbarium at L.

Homotypic synonyms: Hebeloma crustuliniforme var. longicaudum (Pers.) Quadr. (1985) ["1984"]; Derminus longicaudus (Pers.) Henn. (1898); Hebelomatis longicaudum (Pers.) Locq. (1979) [“1977”]; Hylophila crustuliniformis var. longicauda (Pers.) Quél. (1886); Hylophila longicauda (Pers.) Quél. (1888)

Original diagnosis: Agaricus longicaudus: solitarius, pileo subcarnoso planiusculo subviscoso alutaceo, lamellis confertis planis argillaceis subliberis, stipite longissimo albicante. Crescit in ericetosis sylvaticis. Stipes cylindricus, 4 unc. longus, 2-5 lin. crassus. Lamellae lineari-lanceolatae, opacae, vix adnexae, punctatae. Pileus substantia mollis, 1.5 unc. latus.

English translation: Agaricus longicaudus: solitary; pileus thin-fleshed, flattened, subviscid, yellowish-brown, lamellae crowded, plane, pale brown, almost free, stipe very long, whitish. Growing in heath forest. Stipe cylindrical, 10 cm long, 5–15 mm thick. Lamellae linear-lanceolate, opaque, hardly adnexed, punctate. Pileus of soft substance, 6 cm broad.

Commentary: We quote from Grilli (2009b): “as regards Hebeloma longicaudum, however, after considering the serious diffculties connected with both its lectotypification and epitypification, the further use of this name in taxonomical literature is discouraged until the name is typified on the basis of a collection not seriously conflictive with the protologue and, possibly, topotypic.” We believe we cannot, unambiguously, interpret this species.

Full name: Hebeloma longicaudum var. radicatum (Cooke) Sacc. (1887)
Published: Syll. Fung. 5: 801 (1887)
Taxonomic status: Heterotypic synonym of H. birrus
Basionym: Agaricus longicaudus var. radicatus Cooke (1886)

Types: Cooke, Illustr. Br. Fungi: 801 (1884) t. 416, lectotype (icon) designated by Beker et al., Hebeloma (Fr.) P. Kumm.: (2016) page 609 (MBT203034)

This icon was mentioned within the protologue, so was clearly part of the original material.

Homotypic synonym of: Hebeloma radicatum (Cooke) Maire (1908)

Diagnosis: Furnished with a root, radix. Stem fusiform, rooting.

Commentary: See Hebeloma radicatum (Cooke) Maire.

Full name: Hebelomatis longicaudum (Pers.) Locq. (1979) [“1977”]
Published: Flore Mycologique Vol III - Text. Cortinariales A: 146 (1979) ["1977"]
Taxonomic status: This is a Hebeloma but we have not been able to unambiguously determine the species.
Notes: Nom. inval. (art. 41.5 - Melbourne).

Basionym: Agaricus longicaudus Pers. (1801): Fr. (1821)

Types: Not designated. There is no original or authentic material in Persoon's herbarium at L.

Homotypic synonym of: Hebeloma longicaudum (Pers.) P. Kumm. (1871)

Commentary: See Hebeloma longicaudum (Pers.) P. Kumm.