73. CHENIA Plate 104.

Chenia Zand., Phytologia 65: 424, 1989. Type: Chenia subobliqua (Williams) Zand.

Phascum sect. Leptophascum C. Müll., Flora 71: 7, 1888. Type: Phascum leptophyllum C. Müll.

Phascum subg. Leptophascum (C. Müll.) Roth, Aussereur. Laubm. 2: 214, 1911.

Plants forming turfs, occasionally rosulate, green above, brownish below. Stems seldom branching, 0.3–1.0 cm in length, transverse section rounded, central strand weak to strong, sclerodermis present, hyalodermis absent; axillary hairs small, of 3–4 cells, basal cell firm-walled; rhizoids usually few. Leaves appressed and somewhat contorted when dry, spreading when moist, ligulate to spathulate, 1.5–2.5 µm in length, upper lamina occasionally grooved along costa, plane or broadly channeled across leaf, margins plane above, weakly recurved below, sharply crenulate to irregularly dentate above with sharp mid-marginal wall projections usually ending in a weak simple papilla, marginal cells often smaller than the medial; apex rounded to broadly acute, often sharply apiculate by a distinctive thick-walled cell or cells; base rectangular or not differentiated in shape; costa weak, ending several (6–9) cells before the apex or percurrent, costa with lamina inserted ventrally to laterally, ventral and dorsal superficial cells short-rectangular, narrower than laminal cells, 2 rows of cells across costa ventrally at midleaf, costal transverse section rounded to elliptical, stereid band very weak or occasionally absent, rounded in shape, ventral and dorsal epidermis present, guide cells 2 in 1 layer, hydroid strand present, small to large; upper laminal cells large, bulging-hexagonal, 15–18 µm in width, 1:1, walls thin, weakly trigonous, superficially convex on both sides; papillae absent (upper marginal teeth may be interpreted as ending in sharp, simple papillae); basal cells differentiated across the leaf base (except for one row of marginal cells similar to the upper cells), rectangular, ca. 20–25 µm in width, 2–4:1, walls thin, weakly trigonous. Propagula when present borne on rhizoids in soil, irregularly rounded to clavate, ca. 100–130 µm in longest dimension. Dioicous. Perichaetia terminal, inner leaves little different from the cauline, slightlylarger.Seta ca. 0.1–1.2 cm in length, 1 per perichaetium, reddish brown, twisted clockwise; when present theca 0.7–2.0 µm in length, brown, nearly spherical (then with a narrow beak to 0.25 µm in length) or short-ovate or cylindrical, exothecial cells rectangular, 20–45 µm in width, 1–4:1, thin-walled, stomates at base of theca, phaneropore, cleistocarpous or stegocarpous, annulus when present of 2–3 layers of strongly vesiculose cells, persistent; when present peristome teeth 32, filamentous, somewhat anastomosing, densely branching-spiculose, ca. 400 µm in length, with ca. 5 articulations, nearly straight or weakly twisted counterclockwise, basal membrane 25–35 µm in height, low spiculose. Operculum when differentiated short- to long-conic, 500–650 µm in length, cells twisted weakly counterclockwise. Calyptra cucullate or mitriform and then three-lobed, smooth, 1.5–2.0 µm in length. Spores 10–20 µm in diameter, light brown, nearly smooth to finely papillose. Laminal KOH color reaction red. [Information on the cleistocarpous sporophyte of C. leptophylla from Arts and Sollman 1991]

Found on soil from sea level to nearly 3000 meters elevation; North and South America, Europe, eastern Asia and Australia.

Corley et al. (1981) suggested that Chenia leptophylla (as Tortula rhizophylla) “is completely anomalous in Tortula.” The Andean C. obliqua (Pl. 104, f. 1–8) is closely related and differs from C. rhizophylla in the peristomate sporophyte, broad leaf apex, margins strongly dentate in the upper 1/3 of the leaf and lacking a leaf apiculus of thick-walled cells. Although these two species are rather different, a third species, C. lorentzii (Pl. 104, f. 14–18), is sterile but otherwise intermediate in character, with narrower leaves, not or moderately dentate, and the apiculus is occasionally differentiated and thick-walled. Small, sterile plants mixed in with the type of C. lorentzii are quite like C. leptophylla. The autoicous condition ascribed to C. lorentzii in the original description cannot be confirmed as no antheridia were found in the NY isotype.

Like Stegonia, Chenia is a small genus that includes both peristomate and cleistocarpous species. Chenia is easily distinguished from other Tortula-like species by the combination of the dentate upper leaf margins, large, epapillose upper laminal cells, a thin costa (Pl. 104, f. 12), and red coloration in KOH. The last may have to be determined by examination of the upper laminal cell walls under high magnification because the dense yellow-green of the chlorophyll overwhelms the color of the very thin cell walls. The leaf teeth are each usually tipped with a single, simple papilla. Phascum leptophyllum of central and southern Africa, an earlier name than Physcomitrium rhizophyllum Sak., was reported by Arts and Sollman (1991) to be the same as C. rhizophylla, along with Pottia denticulata Dix. & Varde of India and P. splachnobryoides C. Müll. of Asia; they describe and illustrate the sporophyte with its cleistocarpous capsule, and review the literature on this widely distributed species. Chenia leptophylla is, as is the case with Didymodon australasiae var. umbrosus (cf. Crundwell & Whitehouse 1978, Eckel 1986a, Preston & Whitehouse 1985, Synnott & Robinson 1990, and others), apparently spread by human agency through rhizoid-borne propagula (Pl. 104, f. 13) in the soil. Chenia is similar to Hennediella, especially H. serrulata (which has a quite similar gametophytic appearance); also, Tortula paulsenii has somewhat similar morphology. Phylogenetic analysis indicates a close relationship, however, to Syntrichia (see Cladograms 13 and 14).

Additional literature: Cortini and Aleffi (1989), Iwatsuki and Saito (1972), Martinez et al. (1989), Neumann (1972), Pedrotti and Aleffi (1989), Reese (1967, 1968), Smith and Whitehouse (1974), Sollman (1979), Stone (1980a).

Number of accepted species: 3.

Species examined: C. lorentzii (NY), C. leptophylla (BUF, PAC), C. subobliqua (NY).

New combinations: Chenia leptophylla (C. Müll.) Zand., comb. nov. (Phascum leptophyllum C. Müll., Flora 71: 6, 1888). Chenia lorentzii (C. Müll.) Zand., comb. nov. (Barbula lorentzii C. Müll., Linnaea 42: 346, 1879 [“-i”]; Tortula lorentzii (C. Müll.) Broth.