It can be distinguished from the others by the single, ovate or roughly triangular, large-celled appendage of the ventral scales, by the distinctly lobed disc of the carpocephalum, with purple paleae protruding from the notches and by the slightly broader-based paleae (up to 7 cells wide).
Thalli large, in crowded, overlying mats; yellowish green, not areolate, pores hardly raised, margins dark red, gently scalloped, somewhat undulate; when dry, thallus margins slightly raised to inflexed. Branches simple or once pseudodichotomously furcate, sometimes with apical or ventrolateral innovations, broadly ligulate, widening rapidly from narrow base, 30-40(-75) mm long, 4.7-7.1 mm wide, 60O-80O(-95O) µm thick medianly, in section 7 or 8 times wider than thick, apex notched, tips of scale appendages recurved over edge; groove absent, thallus dorsally flat to slightly concave, margins acute, thin; flanks sloping obliquely, reddish purple; ventral face medianly keeled, green. Scales in 2 ventral rows, obliquely triangular, purple-red, pink or hyaline, body 1000-1100 µm long, margin ± entire, base 950-1050 µm wide, continuing into long tail below, narrowed above, constricted where joined to large, ovate or roughly triangular appendage, (850-)1050-1200 µm long, apex apiculate, width 420-500 µm across widest part, cells distinctly larger than in base, ± 9 oil cells scattered throughout scale. Dorsal epidermal cells unistratose, containing chloroplasts, thin-walled, 5- or 6-sided, 50-95 x 25-35 µm; air pores very slightly raised, simple, ± 17.5 x 8.0 µm, surrounded by innermost ring of small, collapsed cells and then by 2 concentric rings of (6-)7-9 larger cells in each. Assimilation tissue (150-)250-320 µm thick, air chambers small, empty, in several storeys, bounding walls chlorophyllose; storage tissue 450-650 µm thick over keel, thinning out laterally, absent at margins, cells angular, walls thick, porate and sometimes with a network of striations; oil cells scattered throughout tissues. Autoicous. Androecia in sessile, thickened cushions, oval or elongated or heart-shaped, near apex of main branch, or of ventrolateral innovation, antheridia immersed, opening above into conspicuous papillae. Gynoecial receptacles proximal to apical notch of main branch, single, occasionally paired at apices of 2 furcate branches, ± sessile when young, surrounded by up to 70 purple paleae, not arching over disc, at maturity raised on stalk; carpocephalum rounded, 3.5-5.0 mm across when bearing 4 or 5 capsules, sometimes with only 1 or 2, then smaller and asymmetric, above almost smooth or with low papillae further down. Stalk arising ± 2 mm proximal to apex of branch in apical notch, length variable, (2-)4-10(-20) mm long, often purple, widening toward base, at midlength ± 600 µm wide, with rhizoid furrow, at summit of stalk (and protruding from notches in head), dark purple paleae, occasionally pink or colourless, length variable, up to 2000 µm long, rarely as much as 3250 µm long, but then narrower, and only 3 cell rows wide, mostly up to 7 cell rows or ± 325 µm wide at base, gradually tapering to conical apical cell. Involucre membranous, partly covering capsule below. Pseudoperianths extending up to 1500 µm beyond involucre, generally with 16 segments, white or purple-stained, tapering to narrow, connate tips. Sporophyte with globose capsule, thin-walled and lacking thickening bands. Spores 115.0-152.5 µm diam., triangular-globular, mostly yellow; wing thin, somewhat scalloped, 20.0-22.5 µm wide, margin crenulate; distal face convex, with network of 5-8, ± smooth, angular, complete or incomplete alveoli across and extending over wing to margin on both sides, 25-30 x 20-25 µm, small subsidiary alveoli sometimes present and extending over crests of main ridges, 7.5-10.0 µm high; proximal face with prominent triradiate ridge, its arms up to 25 µm high and continuous from the pole across wing to margin, each of 3 facets with rounded alveoli, up to 20 x 20 µm, some with small, subsidiary alveoli, others appearing smooth and hollowed out. Elaters 225-230 µm long, 17.5 µm wide in centre, slightly tapering to ends, 12.5 µm wide, sometimes branched, bispiral, yellow.