11. TUERCKHEIMIA Plate 14.

Tuerckheimia Broth., Öfv. F. Vet.-Soc. Förh. 52A (7): 2, 1910. Type: Tuerckheimia guatemalensis Broth.

Plants growing in a turf, light to dark green and somewhat glaucous throughout, seldom to commonly branching. Stem to 2.5 cm in length, in transverse section rounded-pentagonal or triangular, central strand present, sclerodermis absent or weakly developed, hyalodermis rarely differentiated; axillary hairs up to 16 cells in length, the basal cell occasionally brown; red tomentum sometimes present; heterotrichous, persistent protonema occasionally present, with green, much branched, aerial chloronemata and green to red-brown caulonemata. Leaves about equal-sized to near base, spreading-incurved from the insertion and subtubulose, weakly twisted to crisped or catenulate when dry, widely spreading when moist, oblong- to linear-lanceolate, to 3.2 mm in length; margins plane to weakly incurved, entire or sometimes deeply dentate, occasionally bistratose in patches; apex narrowly acute; base not or weakly differentiated in shape to short-ovate; costa percurrent and ending in an apiculus to stoutly excurrent as a short mucro, ventral superficial cells quadrate to short-rectangular, papillose, 4–6 cells across costa at midleaf, costa in transverse section circular or ovate, ventrally commonly bulging, with two stereid bands, both usually strong, the dorsal crescent-shaped, two or more guide cells in one layer, a ventral and sometimes a dorsal epidermis present, hydroid strand absent; upper laminal cells subquadrate to hexagonal or elliptical, ca. 10–14 µm in width, 1:1, somewhat bulliform, walls evenly thickened or occasionally trigonous or irregularly thickened, lumens angular or rounded; papillae usually massive, simple, bifid or multifid, usually centered over the lumens, (1–)2–4(–6) salients per lumen; basal cells differentiated in a small group across the leaf base, smooth, rectangular, yellowish to hyaline. Dioicous. Perichaetia terminal, leaves abruptly sheathing below, otherwise little different from cauline leaves, somewhat larger or smaller. Perigonia terminal, gemmate. Seta ca. 4–8 mm in length, reddish to yellowish brown, twisted clockwise above; theca ellipsoidal to short-cylindrical, brown, ca. 1.0–1.5 mm in length, stomates phaneropore, at base of theca, annulus not vesiculose to strongly so but of persistent cells; peristome absent or present but eroded (or possibly rudimentary), consisting of a basal membrane 20–25 µm in height, papillose, retaining the extreme basal portions of one or two narrow papillose teeth. Operculum long-rostrate, ca. 1 mm in length, cells in straight rows. Calyptra not seen. Spores ca. 8–13 µm in diameter, essentially smooth. Laminal KOH color reaction yellow.

Found on mostly calcareous substrates in moist areas in U.S.A. (southeastern states and Alaska), Mexico, Central America, and Eastern Asia.

The major characteristics of Tuerckheimia are the narrow, stoutly mucronate leaves with broadly channeled ventral surfaces, acute apices, plane margins, and generally massive papillae centered over the lumens of the often rather large and bulliform upper laminal cells (Pl. 14, f. 6, 7, 15). The basal laminal cells are poorly differentiated (Pl. 14, f. 5) and do not run up the margins as a vee, as in Tortella. Fruiting plants are rare and reproduction in some species may take place largely through fragile leaf apices. The deeply dentate leaves of Tuerckheimia valeriana are suggestive of Leptodontium but the central strand and short cells of the ventral surface of the costa are features distinguishing Tuerckheimia; T. valeriana, for which sporophytes are unknown, may actually be a Ptychomitrium with anomalous papillae.

There is a resemblance to Eucladium, with its long-lanceolate leaves, large upper laminal cells generally larger medially and with simple papillae, and the generally stoutly excurrent mucro. The upper laminal cells of Tuerckheimia robusta have the angular lumens of Hymenostylium. The narrow, plane leaves of Tuerckheimia are like of those of Trichostomum, but species of that genus generally have small cells and crowded, multiplex, flattened papillae covering most of the cell. K. Saito annotated the type specimen of T. guatemalensis (Pl. 14, f. 8–13) with a new combination (unpublished) in Trichostomopsis (a genus here referred to Didymodon sect. Asteriscium), apparently based on bistratose upper margins. These last were made much of by Brotherus (1910) and Bartram (1949), but are merely patches of bistratose cells not comparable to the completely bistratose margins of, e.g. Didymodon umbrosus, which has similar long-lanceolate leaves. Didymodon sect. Asteriscium is easily distinguished by the much differentiated leaf base and general lack of a ventral stereid band. Quaesticula is similar in areolation but has infolded upper laminal margins, and a rounded-acute, often cucullate leaf apex.

Remnants of a papillose basal membrane that were found at a capsule mouth (Pl. 14, f. 13) in the single known specimen (Guatemala, Livingston, Tuerckheim, 1908, holotype, H) of T. guatemalensis indicate the presence of a peristome in this one species. Additional material is necessary to ascertain the exact morphology of this feature.

Crosby et al. (1992) found Gymnostomum angustifolium Saito and thus its combination Tuerckheimia angustifolia (Saito) Zand. to be invalid names because a single element was not cited as holotype. The correct name for that taxon is now T. svihlae (Bartr.) Zand.

Additional literature: Iwatsuki and Sharp (1958), Zander (1978f).

Species recognized: 4.

Species examined: T. guatemalensis (H, NY), T. robusta (BM), T. svihlae (BUF, DUKE, MEXU, TENN), T. valerianum (DUKE, FH, MICH).

New heterotypic synonymy: Tuerckheimia angustifolia (Saito) Zand. = Tuerckheimia svihlae (Bartr.) Zand.

New combinations: Tuerckheimia robusta (Dix.) Zand., comb. nov. (Merceyopsis robusta Dix., Ann. Bryol. 3: 59, 1930). Tuerckheimia svihlae (Bartr.) Zand., comb. nov. (Trichostomum svihlae Bartr., Rev. Bryol. Lichénol. 23: 245, 1954; Oxystegus svihlae (Bartr.) Gangulee).