Flora of New Zealand Series

Scapania (Dumort.) Dumort., Recueil Observ. Jungerm. 14. 1835.

Type (cons.): Scapania undulata (L.) Dumort. (≡Jungermannia undulata L.)

Plants usually loosely prostrate, rarely strongly ascending unless crowded, pale green or reddish brown to purplish, variable in size but mostly vigorous, to 8(10) mm wide, to 25 cm long, the shoots typically strongly dorsiventrally flattened. Branching very sparingly, the branches mostly lateral-intercalary and clearly axillary, but sometimes from ventral end of axil; Radula -type, basiscopic terminal branches sporadic; Frullania -type branches very rare. Stems with cortex usually well differentiated, in 2–3 layers of small, thick-walled cells, the stems then not or rarely mycorrhizal, the cortex at times hardly differentiated and 1-stratose, then with the medulla often mycorrhizal. Rhizoids usually abundant, scattered, often long and forming a dense mat. Leaves widely spreading in a single plane, the leaf bases not conspicuously sheathing (except in subg. Buchiella), deeply complicate-bilobed, ± sharply conduplicate, usually keeled, the keel usually well defined and sharp, weak or rounded in subg. Scapaniella and subg. Buchiella, diverging from stem from its point of origin, often arched, of varying length (0.1–0.8 the length of ventral lobe), often winged, at least above, the dorsal lobe smaller than the ventral, the leaf insertion in dorsal half at times merely transverse, but in many taxa arched and ± strongly decurrent, ventral half of insertion arched, ± decurrent, often strongly so. Dorsal and ventral lobes usually similar in shape, elliptical-oblong to broadly ovate-rotundate to reniform, with apices rounded to apiculate, the lobe margins usually closely, varyingly, mostly sharply denticulate-dentate (but not serrulate), to sometimes ciliolate or ciliate or entire (in some smaller taxa), the teeth often of strongly differentiated cells. Cells with walls thin (except at times the marginal several rows) to thick-walled, with ± well-defined, often nodose trigones; surface smooth or papillose, rarely closely and coarsely so. Oil-bodies (Schuster, 1974a) (1)2–12 per median cell, fine segmented. Asexual reproduction (probably in all taxa) via gemmae, the gemmae 1–2-celled, smooth, ovoid to ellipsoidal, developing from the immature leaf lobes.

Dioecious, rarely (not in ours) paroecious, never autoecious. Androecial bracts leaf-like but somewhat (rarely conspicuously) concave at base, the dorsal and ventral lobes often more nearly equal in size, often without teeth; antheridia (1)2–5, rarely more; paraphyllia often interspersed among antheridia. Gynoecial bracts somewhat larger but not sharply differentiated from leaves. Perianth (few non-Austral exceptions) strongly dorsiventrally flattened, distally parallel-sided, with only (usually sharp) lateral, parallel keels, the mouth wide, truncate, often deflexed, entire or dentate to ciliate.

Seta massive, of numerous undifferentiated cells. Capsule ovoid to oblong-ovoid, the wall (3)4–7-layered; outer layer of cells with strong (sometimes confluent) nodular thickenings; innermost layer of cells with incomplete to complete semiannular bands.

Spores small, usually 1.3–1.6(2)× the elaters in diam. Elaters bispiral.

A large genus of over 110 species according to Potemkin (1998), 90–100 according to Váňa (1996). The genus has a major concentration of species in the Holarctic. The few tropical species of the genus are restricted to high elevations, e.g., Scapania portoricensis Gottsche is endemic to the Neotropics and widespread in mountainous regions. Schuster (1974a) recognized some nine subgenera, and of these, four occur as isolated, often rare elements in Austral areas:

1) subg. Scapaniella (Buch) Jörg., with S. gamundiae R.M.Schust. of Tierra del Fuego and the maritime Antarctic, where it is exceedingly rare and localized, known from a single collection on Signy Island (Bednarek-Ochyra et al., 2000);

2) subg. Jensenia S.W.Arnel l, which includes S. obcordata (Berggr.) S.W.Arnel l, a bipolar species of the high Arctic and exceedingly rare and localized in the maritime Antarctic, known only on the South Orkney Islands and the South Shetland Islands (Ochyra and Váňa, 1989; Bednarek-Ochyra et al., 2000) and also S. valdonsmithii R.M.Schust. (nom. inval.) of Prince Edward Island;

3) subg. Scapania, with S. nemorosa (L.) Dumort. and S. undulata (L.) Dumort. both of New Zealand. Note also that S. macgregorii of New Guinea belongs here.

4) subg. Macroscapania R.M.Schust., with S. cuspiduligera (Nees) Müll.Frib., reported from Zaire (Váňa et al., 1979) and Lesotho and Natal (Hodgetts et al., 1999). Scapania hedbergii S.W.Arnell is endemic to Kenya and S. esterhuyseniae S.W.Arnell is known from Uganda and Tanzania. Note that Arnell (1963) does not report the genus (or family) from South Africa.

Potemkin (1998) subdivided the genus into 16 sections, but did not recognize subgenera.

Genus description after Schuster (2002a) but freely modified.

References: Potemkin (1998); Schuster (1974a, 1999c, 2002a).