Acroporium caespitosum (Hedw.) W.R.Buck

Authority

Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.

Family

Sematophyllaceae

Scientific Name

Acroporium caespitosum (Hedw.) W.R.Buck

Description

Species Description - Plants medium-sized, in mostly lustrous, ± stiff, yellow- to golden-green, usually compact mats. Stems creeping, to ca. 4 cm long, freely but irregularly branched, the branches ascending, short, cuspidate; in cross-section with 2-3 rows of small thick-walled colored cells surrounding large firm-walled cells, central strand absent; pseudoparaphyllia foliose; axillary hairs with a single rectangular brown basal cell and (l-)2 elongate hyaline distal cells. Stem and branch leaves similar, erect-spreading, oblong-lanceolate to ovate-lanceolate, 0.9-1.3 X 0.24-0.33 mm, often ± abruptly acuminate, concave; margins entire to subserrulate-crenulate throughout, plane or incurved above; costa short and double or absent; cells linear-flexuose, smooth, thick-walled, slightly porose, becoming yellow and very porose toward the insertion; alar cells 3-4 in each basal angle, curved to the insertion, greatly enlarged and inflated, yellow to hyaline, oval to oblong. Asexual propagula none. Autoicous. Perichaetia inconspicuous, on stems and extreme bases of branches; leaves erect, ovate, ca. 1 mm long, short-acuminate; margins serrate above, subentire below, plane; costa mostly none; cells linear-flexuose, smooth, firm-walled, not or only slightly porose, becoming shorter, broader and thinner-walled toward the insertion; alar cells not differentiated. Setae elongate, slender, slightly roughened above, reddish, 1.2-1.5 cm long, flexuose, curved just below the urn; capsules inclined, small, ± asymmetric, short-cylindric, 0.7-0.9 mm long; exothecial cells subquadrate, strongly collenchymatous, becoming oblate and evenly firm-walled in 0-2 rows at the mouth; annulus not differentiated; operculum obliquely and slenderly long-rostrate, longer than the urn; exostome teeth triangular, yellowish, shouldered, bordered, on the front surface with a narrow median furrow, cross-striolate below, coarsely papillose above, trabeculate at back; endostome with a high basal membrane, segments papillose, narrow, keeled, perforate, shorter than the teeth, cilia single or rarely in pairs. Spores spherical, ± smooth, 11-15 µm diam. Calyptrae cucullate, naked, smooth.

Discussion

2. Acroporium caespitosum (Hedw.) W. R. Buck, Brittonia 35: 310. 1983; Leskea caespitosa Hedw., Sp. Musc. Frond. 233. 1801, non Leskea caespitosa Sw., Fl. Ind. Occid. 3: 1807. 1806, horn, illeg., nec Sematophyllum caespitosum [Sw.] Mitt., J. Linn. Soc., Bot. 12: 479. 1869; Hypnum caespitosum (Hedw.) Schrad., J. Bot. (Schrader) 5: 200. 1803, non Wilson, Hooker J. Bot. 3: 385. 1841, hom. illeg. [= Scleropodium cespitans (Müll. Hal.) L. F. Koch]. Plate 145, figures 8-16 Sematophyllum lamprophyllum Mitt., J. Linn. Soc., Bot. 12: 496. 1869; Rhaphidostegium lamprophyllum (Mitt.) A. Jaeger, Ber. Thätigk. St. Gallischen Natur-wiss. Ges. 1876-77: 411. 1878; Pungentella lamprophylla (Mitt.) Müll. Hal., Bot. Jahrb. Syst. 23: 330. 1896, comb. inval. Sematophyllum sericifolium var. leonii Thér., Mem. Soc. Cub. Hist. Nat. “Felipe Poey” 15: 221. 1941; Sematophyllum leonii Thér., Mem. Soc. Cub. Hist. Nat. “Felipe Poey” 15: 221. 1941, nom. nud. in s\n. Sematophyllum sericifolium fo. longiseta Thér., Rev. Bryol. Lichénol. 14: 21. 1944, nom. nud. Acroporium jamaicense H. A. Crum & E. B. Bartram, Bull. Inst. Jamaica, Sci. Ser. 8: 66. 1958. Discussion. Obviously related to Acroporium pungens, A. caespitosum may be separated by the smaller, narrower leaves that are more abruptly tapered. Also, A. pungens often grows on twigs and branches, whereas A. caespitosum more typically grows on tree trunks. Acroporium caespitosum seems closely related to A. smallii (R. S. Williams) H. A. Crum & L. E. Anderson of southern Florida, but differs from that species by significantly larger leaves that are somewhat more concave. The relatively narrow ranges of so many species of Acroporium is unusual in a family that has so many widespread, weedy species. This unfortunately may suggest that many of the scores of names in the genus may truly be good. The nomenclature of this species is confused because the same epithet, caespitosum, was used by both Hedwig (1801) and Swartz (1806) for very different plants. This was realized long ago (Dixon, 1920) but the nomenclatural complexities were ignored. More recently, I (Buck, 1983b) clarified the nomenclature and sorted out the epithets.

Distribution

Range. Probably endemic to the West Indies; Cuba, Jamaica, Hispaniola (Haiti and Dominican Republic), Puerto Rico, Guadeloupe, Dominica, Martinique; mostly growing on tree trunks and rotten logs, rarely rocks, in humid forests, at 500-1750 m.

West Indies| Cuba South America| Jamaica South America| Haiti South America| Dominican Republic South America| Puerto Rico South America| Guadeloupe South America| Dominica South America| Martinique South America|