14. CALYPTOPOGON Plate 17.

Calyptopogon (Mitt.) Broth., Nat. Pfl. 1(3): 419, 1902.

Streptopogon sect. Calyptopogon Mitt., Phil. Trans. R. Soc. London 168: 33, 1879. Type: Calyptopogon mnioides (Schwaegr.) Broth.

From ka_lupto'V,covered+ o + pw'gwn,-wnoV, beard; referring to the ragged margin of the calyptra.

Plants growing in tufts or mats, yellowish green above, brown below. Stems branching occasionally, 2–4 cm in length, transverse section rounded-pentagonal, central strand absent, sclerodermis present, hyalodermis present, occasionally only in patches; axillary hairs to 7 cells in length, all hyaline or 1–2 basal cells thick-walled; sparsely to densely radiculose. Leaves incurved or catenulate, margins extremely undulate when dry, widely spreading and reflexed when moist, long-ovate to ovate-lanceolate, 3.5–4.5 mm in length, upper lamina flat to somewhat keeled, margins plane, nearly entire, minutely serrulate with projecting transverse cell walls and papillae, bordered intramarginally throughout length of leaf by 3–4 rows of rectangular epapillose porose cells as an extension of the region of differentiated basal cells; apex acute, often narrowly channeled, extreme cells bordering the mucro rhomboid; base little differentiated in shape but tubulose-clasping; costa evenly tapering, excurrent as a papillose mucro, superficial cells short-rectangular and distantly papillose ventrally, elongate and distantly papillose with forward-pointing cell ends dorsally, ca. 4 rows of cells across costa ventrally at midleaf, costal transverse section ovate, stereid band absent ventrally, strong dorsally and crescent-shaped, lumens of stereid cells smaller towards dorsal surface, substereid near guide cells, ventral epidermis of bulging or conic cells, dorsal epidermis absent, guide cells 2–4(–6) in 1(–2) layers, hydroid strand very large, ventral costal cells often protuberant as scattered, ovate, thick-walled cells; upper laminal cells irregularly hexagonal, occasionally longitudinally or transversely elliptic, ca. 12–16 µm in width, ca. 1:1, walls trigonous, porose, superficially weakly convex on both sides; papillae small, simple to bifid, conic-spiculose, solid, 3–4 per lumen, evenly scattered over the lamina; basal cells differentiated across leaf, rising higher marginally and fusing with the intramarginal border, rectangular, little wider than upper cells, to 5–6:1, walls evenly thickened to porose. Propagula multicellular, caltrop-shaped, 20–30 µm in diameter, borne on the ventral surface of the costa. Dioicous. Perichaetia terminal, inner leaves strongly differentiated, linear-lanceolate, to 12–13 mm in length, strongly sheathing, convolute, cells entirely rectangular to long-rhomboidal, thick-walled and porose. Perigonia born terminally on an equal-sized perigoniate plant as gemmate buds, often several per plant, each ending a branch. Seta short, ca. 0.5 cm in length, 1 per perichaetium, brown, twisted clockwise; theca 1.8–2.2 mm in length, brown, short-rectangular, occasionally curved, exothecial cells rectangular, evenly thickened, ca. 20 µm in width, 2–4:1, stomates phaneropore, at base of capsule, annulus of 3–4 rows of somewhat vesiculose, persistent cells; peristome often coming off with the operculum, teeth 32, filamentous, densely low-spiculose, to 500 µm, with many articulations, twisted once counterclockwise, basal membrane high, to 300 µm in height, with round, thin-walled windows, densely low-spiculose. Operculum conic, ca. 1.5 mm in length, cells twisted counterclockwise. Calyptra cucullate, somewhat rough above, ragged and longitudinally undulate below, smooth, ca. 3 mm in length. Spores ca. 13–15 µm in diameter, brown, essentially smooth. Laminal KOH color reaction red, often blotchy, or yellow with red blotches, or yellow-orange.

This monotypic rupestral genus is restricted to southern South America, New Zealand, Tasmania and Australia.

Sainsbury (1955) described the calyptra as mitriform, but it is actually long-cucullate, weakly pleated and strongly frayed at the base (Pl. 17, f. 17). The genus is distinctive in the combination of the trigonous upper laminal cells with small, simple to bifid, solid papillae (Pl. 17, f. 6); intramarginal border of porose, rectangular, epapillose cells (Pl. 17, f. 10); single costal stereid band (Pl. 17, f. 8–9); nerve-borne, short-branching propagula (Pl. 17, f. 11); convolute-sheathing perichaetial leaves of thick-walled porose cells (Pl. 17, f. 12–13); and 32 filamentous peristome teeth (Pl. 17, f. 15). Sections of the costa near the base show more than one hydroid strand and a clear differentiation of tissues into a crescent of 2 or 3 superficial rows of stereids dorsally, and substereid cells just ventral to that crescent, the significance of which is presently unclear. Older axillary hairs apparently become thick-walled basally; hairs near the apex are entirely hyaline.

The ventral stereid band is absent, as is characteristic of highly evolved taxa of the Pottioideae. This genus is strongly reminiscent of Syntrichia papillosa (Pottieae), a species of broad distribution fruiting, however, only in Australia (cf. Catcheside 1980 and Dixon 1923). Syntrichia papillosa shares the following features with Calyptopogon: large, collenchymatous upper laminal cells; papillae simple (occasionally bifid); stereid band crescent-shaped; no dorsal epidermis; hydroid strand strong; propagula clavate with bulging cells, borne on ventral surface of costa; perichaetial leaves strongly sheathing the costa, laminal cells rhomboidal and hyaline throughout; calyptra large; KOH red. Syntrichia papillosa was thought by Kramer (1980) to possibly form its own section of Tortula. It differs from Calyptopogon by its stem having a (weak) central strand; awned, concave leaves lacking a leaf border and not strongly undulate marginally when dry; upper laminal cells smooth or only singly papillose; apically dorsally spinose costa; and perichaetial leaf cell walls not thickened. Syntrichia pagorum has, like C. mnioides, a semicircular costal section, which lacks dorsal epidermal cells and bulges laterally over the dorsal surface of the leaf, and the species likewise fruits only in austral regions (cf. Catcheside 1980; Stone 1971); S. pagorum differs, however, in the only weakly differentiated perichaetial leaves and the relatively small, multiplex-papillose upper laminal cells characteristic of Syntrichia. The cladistic study, however, places Calyptopogon in the Trichostomoideae.

Number of accepted species: 1.

Species examined: C. mnioides (NY, US).