Monographs Details: Pilotrichidium callicostatum (Müll.Hal.) Besch.
Authority: Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
Description:Species Description - Plants medium-sized to relatively robust, in dull, stiff, dark- to olive-green, sometimes becoming golden with age, often dense, extensive mats. Stems creeping, to ca. 7 cm long, mostly ca. 4 cm long, subpinnately or irregularly branched, ± complanate-foliate; in cross-section with a unistratose hyalodermis over 3-5 rows of small thick-walled cells surrounding larger thin-walled cells, central strand none; pseudoparaphyllia foliose, small; axillary hairs 2-celled, with a short brown basal cell and an elongate hyaline distal cell. Leaves slightly contorted when dry, densely foliate, the lateral leaves erect- to wide-spreading, the dorsal and ventral ones erect, lateral and dorsal leaves oblong to oblong-ovate, 1-1.6(-1.8) mm long, obtuse and sometimes mucronate to apiculate, to acute, ± asymmetric, shortly rounded to the insertion; margins entire throughout except for projecting papillae, denser above, plane or narrowly incurved in lower 1/2; costa double, strong, subpercurrent or rarely percurrent to short-excurrent, ± parallel except ± connivent at apex, projecting at apex as single spines; cells mostly irregularly isodiametric, 5-6 µm wide, pluripapillose with 2-4(-7) papillae per cell, thin-walled, not porose, becoming short-rectangular, 3-6:1, and smooth toward the insertion; alar cells not differentiated; ventral leaves sometimes differentiated, when so broadly ovate-triangular, ca. 1/2 as long as other leaves, concave, otherwise similar. Asexual propagula not seen but reported by Allen (in litt.) as in leaf axils, stalked, 2-3-celled with the terminal cell greatly enlarged, hyaline. Dioicous. [Sporophytes not seen, description modified from Allen & Crosby, 1986: 48, 50.] Perichaetia on secondary stems and branches; leaves linear, to 1 mm long, broadly obtuse; costa double; cells linear-rectangular, smooth, becoming thick-walled and porose toward insertion. Setae elongate, smooth, 0.9 cm long; capsules erect, oblong, 1.3 mm long, with a short, ± roughened neck; exothecial cells rectangular, firm- to thick-walled; operculum rostrate, ca. as long as the urn; exostome teeth narrowly bordered, on the front surface weakly or not furrowed, the plates cross-striolate below, papillose above, somewhat trabeculate at back, smooth to finely papillose; endostome lightly papillose, segments perforate, cilia none. Spores spherical, smooth, 12-14 µm diam.

Discussion:1. Pilotrichidium callicostatum (Müll. Hal.) A. Jaeger, Ber. Thatigk. St. Gallischen Naturwiss. Ges. 1875-76: 357. 1877; Hookeria callicostata Müll. Hal., Syn. Musc. Frond. 2: 216. 1851; Callicostella callicostata (Müll. Hal.) M. Fleisch., Hedwigia 63: 215. 1922. Discussion. Pilotrichidium callicostatum is characterized by oblong leaves with papillose but otherwise entire margins. The leaf cells are small and obscure from several papillae over each lumen. The species, known in our flora only from Jamaica, differs from all other Hookeriales because of the pluripapillose laminai cells, except Hypnella, with which there is little likelihood of confusion. Unfortunately, the name Pilotrichidium ccdlicostatum has been widely misused for P antillarum (e.g., Crum & Steere, 1957). However, the two are quite distinct and the discussion following P antillarum should be referred to. In the Jamaican moss flora (Crum & Bartram, 1958), P callicostatum was confused with Callicostella diatomophila, which differs in the smooth leaf cells and lack of a differentiated hyalodermis.
Distribution:Mexico North America| Panama Central America| Colombia South America| Venezuela South America| Ecuador South America| Trinidad and Tobago South America| Jamaica South America|