34. Splachnaceae Greville & Arnott
Paul C. Marino
Plants small to medium-sized, green, yellowish, or sometimes brownish, acrocarpous. Stems 2-fid by subfloral innovations; axillary hairs common, minute, claviform. Stem leaves soft, homogeneous along stem or larger and crowded at stem apices, ovate-lanceolate, oblong, or spatulate, broad; margins entire to dentate, sometimes bordered; costa single, strong, usually ending before apex; laminal cells rhomboidal, large; basal cells oblong; distal cells oblong or oblong-hexagonal. Perichaetia with leaves similar, often larger. Seta erect, usually elongate, thin or thick. Capsule erect, exserted, symmetric or slightly curved, neck elongate, or hypophysis wide and inflated or long and narrow, proximal to urn; columella sometimes exserted; stomata many, guard cells 2; annulus usually absent; operculum convex to conic; peristome usually present, single (double in Splachnum); exostome teeth 8-12 or 16, rarely 2-fid, approximate in groups of 2 and 4, densely and finely papillose. Calyptra mitrate or rarely cucullate, smooth, sometimes hairy.
Genera 6, species 73 (5 genera, 20 species in the flora): nearly worldwide; tropical to subpolar regions.
Almost half the species of Splachnaceae possess three noteworthy ecological features. First, their gametophytes are coprophilous, growing on feces, occasionally old bones, and other animal matter. Second, their spores are commonly small and sticky, making them suitable for insect dispersal. Third, the sporophytes of all entomophilous Splachnaceae examined to date produce complex, species-specific odors that are thought to promote the attraction of flies (order Diptera).
Although the leaves of Splachnaceae are soft textured and similar in shape to those of Funariaceae, recent phylogenetic studies suggest that Splachnaceae are more closely related to Meesiaceae than to Funariales as previously proposed. Like many species of Meesiaceae, most Splachnaceae grow in moist habitats such as peatlands in temperate and boreal forests. Splachnaceae differ from Meesiaceae in the structure of the capsule, which in Splachnaceae is erect with a mitrate calyptra, whereas in Meesiaceae the capsule is curved with a cucullate calyptra (B. Goffinet et al. 2004).
SELECTED REFERENCES Bequaert, J. 1921. On the dispersal by flies of the spores of certain mosses of the family Splachnaceae. Bryologist 24: 1-4. Goffinet, B., A. J. Shaw, and C. J. Cox. 2004. Phylogenetic inferences in the dung moss family Splachnaceae from analysis of cpDNA sequence data and implications for the evolution of entomophily. Amer. J. Bot. 91: 748-759. Koponen, A. 1978. The peristome and spores in Splachnaceae and their evolutionary and systematic significance. Bryophyt. Biblioth. 13: 535-567. Koponen, A. 1982. The classification of the Splachnaceae. Beih. Nova Hedwigia 71: 237-245. Marino, P. C. 1988. The North American distribution of the circumboreal species of Splachnum and Tetraplodon. Bryologist 91: 161-166. Marino, P. C. 1997. Competition, dispersal and coexistence of Splachnaceae in patchy habitats. Advances Bryol. 6: 241-264. Marino, P. C., R. Raguso, and B. Goffinet. 2008. The ecology and evolution of fly dispersed dung mosses (family Splachnaceae): Manipulating insect behaviour through odor and visual cues. Symbiosis 47: 61-76.