Andrognathuscorticarius Cope, 1869: 182; Gardner 1975: 15, figs 1, 5–7; Hoffman 1999: 180; Shear and Marek 2009: 157, figs 1–10.

Andrognathuscorticarius Cope, 1869, Andrognathushoffmani Shear & Marek, 2009, Andrognathusgrubbsi sp. n.

Adult Andrognathus differ from other andrognathid genera based on the following:

Exoskeleton: Adults with 45–70 rings. Individuals long (11 to 27 mm) and thin, less than one mm wide, with short paranota, not covering legs (as in Brachycybe). Color varies from cream to dark brown (Figure 1), with paranota lighter, not pink as in Gosodesmus Chamberlin, 1922, Ischnocybe Cook & Loomis, 1928, Brachycybe. Entire body pilose, particularly head and antennae. Head rounded, pear-shaped, nearly truncate, eyeless (Figure 4). Antennae enlarged apically, slightly elbowed at fourth antennomere (Figure 4). Gnathochilarium and labrum tightly appressed, mandibles not visible externally. Anterior margin of labrum smooth, with small depressed triangular area (Figs 4, 5A, B); without ramified cuticular papillae (as in Brachycybe). Paranota of ring five swept forward (anteriorly); distinctly bilobed in corticarius (Figure 2A). Paranotal caudolateral margins posterior to ring five sharply projecting caudally, unlike Gosodesmus where the paranotal margins are quadrate. Porosteles clearly differentiated, ozopores rimmed with peritrema, directed anteriorly on ring five (Figs 2, 5C), laterally on remaining rings. Telson: Hypoproct absent, preanal ring barrel-shaped (Figure 5D). Gonopods: Anterior gonopods rounded and robust; A6 spatulate (Figs 6–9) not with a distal series of thin ribbon-like styli, as in Brachycybe. Posterior gonopod long with P6 extended beyond A6, ending in a variable crown, which may be elongated, spatulate, or bifurcate (Figs 6–9) but never composed of a bundle of styli as in Brachycybe. P6 with medial spur-like process (possibly claw/tarsungulum). See also diagnosis of Andrognathus in Shear and Marek (2009).

Andrognathus was placed in Andrognathinae (a monotypic subfamily) due to the lobed condition of the fifth pair of paranota (Hoffman, 1980).