Flora of New Zealand Series

Paracromastigum Fulford & J.Taylor, Brittonia 13: 336. 1961.

Bonneria Fulford & J.Taylor, Brittonia 13: 334. 1961.

Leucosarmentum Fulford, Mem. New York Bot. Gard. 11: 386. 1968.

Type: Paracromastigum subsimplex (Steph.) Fulford & J.Taylor (≡Lepidozia subsimplex Steph.)

Plants anisophyllous, procumbent, pale green to brownish, typically with an extensive system of stoloniform axes with reduced, bidentate or bilobed leaves; plants small, mostly to 375 µm wide. Branching irregular, the branches variable, predominantly ventral-intercalary, at times also lateral-intercalary; Acromastigum -type branches (only rarely lacking) and Frullania -type branches common, sometimes with Microlepidozia -type branches (with all 3 types of terminal branches present in some species). Stems with cortex mostly firm-walled, occasionally thin-walled, in mostly 7–12 rows (rarely to 17 rows), subequal or weakly to markedly larger than the thin-walled medullary cells. Rhizoids from stem at base of underleaves or from lower cells of underleaf. Leaves remote to feebly imbricate, the insertion (and orientation) variable: weakly incubous and extending to stem midline dorsally (subg. Paracromastigum), to weakly to distinctly succubous and with insertion not extending dorsally to stem midline and delimiting a leaf-free strip of 2 cell rows wide (subg. Austrocephalozia); leaves concave, 2–3-lobed to 0.35–0.8. Cells thin- to feebly and equally thick-walled, trigones absent, the surface smooth (when cells leptodermous) or striate-papillose (when cells firm). Oil-bodies lacking or present as small droplets or, in some species, present in some cells, finely to coarsely botryoidal and 1–3 per cell, in Paracromastigum pachyrhizum (=P. bifidum) 1–2(3) per cell and homogeneous to 3–5-segmented. Underleaves at most 0.6× area of leaves, with 2–4 lobes, the lobes often unequal; disc distinct and several cells high. No asexual reproduction.

Dioecious. Androecia on short, usually ventral- but at times lateral-intercalary branches, often brownish, even if sterile shoots lack pigmentation, spicate; bracts usually in 4–12 to as many as 18 pairs, deeply concave to ventricose, the apices bilobed; antheridia 1 per bract, the stalk 2-seriate; bracteolar antheridia absent or present. Gynoecia on short ventral- and lateral-intercalary branches; bracts of innermost series much larger than leaves, bifid to 0.2–0.6; lobes mostly terminating in a single cell or a uniseriate row of 2–5 cells, the lobe margins with a few teeth or entire; disc margins with small teeth or sparingly crenulate by projecting upper ends of cells; bracteole similar to bracts or a little smaller. Perianth trigonous above, the mouth dentate-ciliolate to lobulate, the teeth usually discrete from one another and terminating in a single cell or a uniseriate row of 2–3 somewhat elongated, at times thick-walled cells, the terminal cell rounded at the summit and not sharp, or (Paracromastigum longiscyphum) the mouth comprised of elongate cells that are laterally free for varying distances; perianth unistratose throughout or locally bistratose toward base.

Seta with 8–9 rows of large outer cells and 11–15 rows of much smaller internal cells. Capsule ellipsoidal, the wall 2–3- or 3-stratose; outer layer of cells with two-phase development, the longitudinal walls with obscure to distinct continuous sheets of secondary wall material and nodular (to rarely weakly extending) thickenings, alternating with primary walls with thickenings absent or in a few species weakly developed; inner cells with a few to several semiannular bands and (commonly) nodular thickenings.

Spores and elaters not seen.

A genus of 12 species. Three species occur in southern South America, Paracromastigum stipulatum (Herzog) Fulford, P. subsimplex (Steph.) Fulford & J.Taylor and P. dusenii (Steph.) R.M.Schust., the latter known from the type (Chile, Prov. Aisén) and recently reported from Serra do Itatiaia in eastern Brazil (Gradstein and Pinheiro da Costa, 2003, p. 209). One species occurs in western Australia, P. longiscyphum (Taylor) R.M.Schust. & J.J.Engel, one in Tristan da Cunha, P. tristanianum (R.M.Schust.) J.J.Engel & R.M.Schust. (the presence of this species in South Africa requires further investigation; see Schuster, 2000a, p. 370), one in South Africa, P. succulentum (Sim) J.J.Engel & Merrill (Engel and Merrill, 2001), and four in our area. The remaining species are Neotropical.

References: Schuster and Engel (1996); Schuster (2000a).

The following key is adapted, with considerable modification, from Schuster (2000a).