Rhachitheciaceae H. Robinson
Bernard Goffinet
Plants small, erect, gregarious. Stems with [or without] central strand. Leaves spathulate, [ovate, oblong, lingulate,] erect spreading when moist, crisped when dry, acute, 1-costate, costa vanishing before apex [minutely excurrent]; laminal cells smooth [papillose], thin-walled, rectangular in proximal half, short-rectangular to isodiametric distally; alar cells not differentiated. Specialized asexual reproduction present [or lacking] as multicellular gemmae, 1- to 2-seriate, to 7 cells in length, borne on surface of leaves. Sexual condition autoicous; perichaetial leaves differentiated [or not]. [Sporophyte solitary in perichaetia. Seta erect, straight or twisted when dry, curved when moist. Capsules immersed to exserted, ribbed, rarely smooth; annulus differentiated or not; endostome teeth fused or not; inner peristomial layer of only 8 or 16 cells, or endostome lacking. Calyptrae cucullate, smooth or papillose, glabrous. Spores striate, pitted or papillose].
Genera 7, species 17 including one fossil species (1 genus and 1 species in the flora): primarily tropical and subtropical regions; North America, Central America, South America, Africa, Asia.
This family includes the genera Hypnodontopsis Z. Iwatsuki & Noguchi, Jonesiobryum B. H. Allen & Pursell, Rhachitheciopsis P. de la Varde, Rhachithecium Le Jolis, Tisserantiella P. de la Varde, Uleastrum W. R. Buck, and Zanderia Goffinet. Previously considered allied to the Orthotrichaceae, and including genera formerly included in that family as well as the Pottiaceae, the Rhachitheciaceae have recently been transferred to the Dicranales (B. Goffinet 1997).
SELECTED REFERENCES
Crum, H. A. & L. E. Anderson. 1981. Mosses of Eastern North America. Volume 1. New York. Crum, H. A. 1993. Rhachitheciaceae. In: A. J. Sharp, H. A. Crum & P. M. Eckel (Eds.), The Moss Flora of Mexico. Mem. New York Bot. Gard, 69: 588--590. Goffinet, B. 1997. The Rhachitheciaceae: revised generic circumscription and ordinal affinities. Bryologist 100: 425--439. Robinson, H. 1964. New taxa and new records of bryophytes from Mexico and Central America. Bryologist 67: 446--458.
