Crossidium · POTTIACEAE 611 GYMNOSTOMIELLA ° CROSSIDIUM 31. CROSSIDIUM Juratzka, Laubm.-Fl. Oesterr.-Ung., 127. 1882, name conserved · [Greek krossos, fringe or tassel, and -idion, diminutive, alluding to tassel-like fringe on adaxial surface of costa] Claudio Delgadillo M. Plants in thin turfs or small cushions. Stem 1–10 mm, central strand present. Leaves evenly distributed or crowded, imbricate to slightly twisted when dry, lingulate, lanceolate to deltoid, 0.5–2.0 mm, 1-stratose, concave in distal half, base rectangular to ovate, margins entire, plane to recurved, apex obtuse, rounded or emarginate; costa excurrent as a whitish hair, in section hydroids present between the stereid and the guide cells, stereid band abaxial, filaments restricted to adaxial surface of costa, filament cells cylindric to subspheric, usually thin-walled, terminal cell cylindric to conic to subspheric, generally thin-walled, often papillose; cells of leaf base rectangular, firm-walled; medial and distal leaf cells quadrate to rectangular, firm-walled, sometimes thick-walled, smooth or with 1 to 8 papillae on either surface. Sexual condition dioicous or monoicous; perigonia budlike, leaves short and broad; perichaetia little or not differentiated. Seta 5–20 mm. Capsule cylindric to ovoid-cylindric, erect; annulus of 1–2 rows of vesiculose cells; operculum conic to rostrate, erect or inclined; peristome short and cribrose to long and twisted. Calyptra cucullate. Spores finely papillose, 9–22 µm. Species 11 (4 in the flora): North America, Mexico, South America, s Europe, n, s Africa, Pacific Islands (New Zealand), Australia. 612 POTTIACEAE · Crossidium Crossidium rosei R. S. Williams, described from Peru, was reported from North America by T. T. McIntosh (1989) from a specimen collected in British Columbia. This is a small sample containing plants of at least three pottiaceous species, including a fertile plant of Pterygoneurum. The type from Peru shows no relationship to the Canadian plants; i.e., Crossidium rosei is not part of the North American flora. Application of the name C. davidai Catcheside by M. J. Cano et al. (1992, 1993) to the Canadian specimen does not account for the lingulate and piliferous leaves of the American material. SELECTED REFERENCES Delgadillo M., C. 1973. A new species, nomenclatural changes, and generic limits in Aloina, Aloinella, and Crossidium. Bryologist 76: 271–277. Delgadillo M., C. 1975. Taxonomic revision of Aloina, Aloinella and Crossidium (Musci). Bryologist 78: 245–303. Cano, M. J., J. Guerra and R. M. Ros. 1993. A revision of the moss genus Crossidium (Pottiaceae) with the description of the new genus Microcrossidium. Pl. Syst. Evol. 188: 213–235. 1. Terminal cell of filaments subspheric, leaf cells papillose. 2. Cells of distal leaf smooth or with 1(–2) papilla on either exposed surface . 1. Crossidium aberrans 2. Cells of distal and mid-leaf pluripapillose . 2. Crossidium seriatum 1. Terminal cell of filaments cylindric or conic, leaf cells usually smooth. 3. Leaves lanceolate to lingulate-ovate; filament cells thin-walled; cells of distal leaf with firm walls; dioicous or cladautoicous . 3. Crossidium crassinervium 3. Leaves broadly deltoid to oblong-ovate; filament cells thick-walled; cells of distal leaf thick-walled, with lumen nearly obliterated; gonioautoicous . 4. Crossidium squamiferum 1. Crossidium aberrans Holzinger & E. B. Bartram, 2. Crossidium seriatum H. A. Crum & Steere, SouthW. Bryologist 27: 4, plate 2. 1924 Naturalist 3: 117, figs. 1–7. 1959 Crossidium spatulifolium Holzinger Plants 1–1.5 mm. Leaves lingulate & E. B. Bartram to oblong-ovate, 0.6–1.3 mm, Plants 2–3.5 mm. Leaves margins revolute from near apex lingulate, lanceolate or ovate, 0.7– to near base, smooth-celled in the 5 1.4 mm, margins recurved from middle and base, apex round to slightly emarginate; costa 5 5 5 5 5 near apex to near base, apex 5 5 5 5 5 excurrent, with an abaxial 5 rounded or emarginate, piliferous; costa excurrent, with an abaxial epidermis, filaments of 2–6 cells, epidermis, filaments of 1–4 cells, cells subspheric, with several cells subspheric, with several papillae per cell, terminal papillae per cell, terminal cell subspheric; cells of leaf cell subspheric; cells of leaf base 13–51 µm, medial and base 24–66 µm, medial and distal cells 13–26 µm, with distal cells 11–20 µm, smooth, with 1–2 abaxial papillae several papillae on either side of distal and median cells. or on either side in distal cells. Sexual condition dioicous Sexual condition cladautoicous. Seta 9–13 mm. Capsule or cladautoicous. Seta 8–16 mm. Capsule urn ovoid- urn oblong-cylindric, 1.5–2.3 mm; operculum 0.7–1.1 cylindric, 1.3–2 mm; operculum 0.5–1 mm; peristome mm; peristome strongly twisted, 1015–1100 µm. Spores strongly twisted, 650–980 µm. Spores spheric, ovoid or spheric, finely papillose, 11–13 µm. oblong, finely papillose, 9–13 µm. Capsules mature Jan–Jul. Sandy soil or rocks, along Capsule mature Jan–Jun(–Aug). Soil and rocks under dry washes, in open or shaded places in deserts; moderate shrubs, shaded banks or in open sites in dry washes; elevations (400–600 m); B.C.; Ariz., Calif., Nev., N.Mex.; moderate elevations (600–1500 m); Ariz., Calif., Colo., Mexico (Baja California); Europe (France, Spain, Nev., N.Mex., Tex., Utah; Mexico (Baja California, Switzerland). Sonora); n Africa. The leaf cells with several papillae on either free surface Crossidium aberrans is easily distinguished by the distinguish Crossidium seriatum from C. aberrans. A smooth or 1-papillose cells of the distal leaf blade and by poorly preserved specimen from Kansas is perhaps a the low filaments with subglobose-papillose terminal cells. juvenile form with awned leaves and reduced filaments. Crossidium · POTTIACEAE 613 3. Crossidium crassinervium (De Notaris) Juratzka, filaments of 4–10 cells, cells cylindric to subspheric, Laubm.-Fl. Oesterr.-Ung., 128. 1882 [thick-walled, terminal cell rectangular, subspheric or Tortula crassinervia De Notaris, Mem. Reale Accad. Sci. conic with 2–5 solid papillae; cells of leaf base 11–70 Torino 40: 303. 1838 µm, medial and distal cells 9–33 µm, smooth, thick- walled. Sexual condition gonioautoicous. Seta 5–20 mm. Varieties 2 (1 in the flora): North America, Europe, Capsule urn short-cylindric to ovoid-cylindric, 1–2.7 mm; n Africa, Asia (China, India), Atlantic Islands (Canary operculum 0.6–1.1 mm; peristome short, nearly straight, Islands). cribose at base to long and strongly twisted, 198–1160 µm. Spores spheric, 9–22 µm. Varieties 2 (2 in the flora): North America, nw Mexico, 3a. Crossidium crassinervium (De Notaris) Juratzka) Europe, Asia (India), n Africa, Atlantic Islands (Canary var. crassinervium Islands). Crossidium desertorum Holzinger & Crossidium squamiferum is a distinctive species E. B. Bartram; C. erosum Holzinger characterized by a whitish marginal area on the distal & E. B. Bartram half of the leaves, thick-walled distal leaf cells, a long Plants 1–5 mm. Leaves lanceolate, hyaline hair point, thick-walled filaments ending in a lingulate to lingulate-ovate, 0.5– papillose terminal cell, and the gonioautoicous sexual 1.3 mm, margins recurved to condition. North American specimens without 5 5 5 sporophytes from Arizona, California, Colorado, and 5 revolute from near apex to near base, apex obtuse, rounded or Utah have been studied, but these cannot be satisfactorily emarginate, piliferous; costa referred to an infraspecific category. The type specimen excurrent, with an abaxial epidermis, filaments 2–12 cells, of C. succulentum is also sterile. cells cylindric, thin-walled, with 2–4 hollow papillae on 1. Capsule ovoid-cylindric with a long and twisted apical cell, terminal cell cylindric or conic; cells of leaf peristome; operculum long-rostrate . base 7–58 µm, medial and distal cells 7–22 µm, smooth. 4a. Crossidium squamiferum var. squamiferum Sexual condition dioicous or cladautoicous. Seta 6–13 1. Capsule cylindric with a short, cribrose peristome; mm. Capsule urn ovoid-cylindric, 0.9–2.2 mm; operculum conic . operculum 0.6–1 mm; peristome strongly twisted, 400– . 4b. Crossidium squamiferum var. pottioideum 900 µm. Spores spheric, nearly smooth to conspicuously papillose, 9–15 µm. 4a. Crossidium squamiferum (Viviani) Juratzka var. Capsule mature Dec–Jul. Soil and rocks, on banks squamiferum and dry washes, under shrubs in desert areas; moderate Crossidium succulentum Holzinger to high elevations (500–1700 m); Ariz., N.Mex., Tex., & E. B. Bartram Utah; Mexico; Europe; Asia (China, India); n Africa; Leaves with margins recurved to Atlantic Islands (Canary Islands). erect distally, undifferentiated in Crossidium crassinervium is characterized by the North American plants. Seta 7– smooth-walled leaf cells and long, thin-walled filaments 20 mm, urn ovoid-cylindric, 1.7– 5 with cylindric to conic terminal cells. Papillae are present 5 2.7 mm; operculum 0.7–1.1 mm; on the apex of the terminal cell and, occasionally, on the peristome long, strongly twisted, distal leaf cells. sometimes cribrose at base, 250– 1160 µm. 4. Crossidium squamiferum (Viviani) Juratzka, Laubm.- Capsules mature (Aug–)Dec–Mar. Soil, sandy soil or Fl. Oesterr.-Ung., 127. 1882 (as squamigerum) rocks, dry washes; moderate elevations (800–1000 m); Barbula squamifera Viviani, Ann. Ariz., Calif.; Europe; Asia (India); n Africa; Atlantic Bot. (Genoa) 1(2): 191. 1804; Islands (Canary Islands). Tortula squamifera (Viviani) De North American specimens of var. squamiferum lack Notaris the differentiated border at the leaf base that is distinctive Plants 6–10 mm. Leaves deltoid- of the taxon elsewhere. Some specimens may show an indistinct proximal leaf border or a peristome somewhat 5 5 5 ovate, oblong-ovate or lanceolate, 5 5 0.6–2 mm, margins recurved to cribrose at base, indicating intergradation with var. erect distally, usually undiffer- pottioideum. Despite this, var. squamiferum is recognized entiated, apex obtuse or rounded, in North America by long setae, ovoid-cylindric capsules, serrulate, with abaxial papillae, piliferous; costa and a long and twisted peristome.