11. TUERCKHEIMIA  Plate 14.

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

     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 K. Saito annotated the type specimen of T. guatemalensis (Pl. 14, f. 8–13) with a new combination (unpublished) in Trichostomopsis (a genus here referred to Didymodon sect.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.