Monographs Details: Calliergonella
Authority: Buck, William R. 1998. Pleurocarpous mosses of the West Indies. Mem. New York Bot. Gard. 82: 1-400.
Description:Genus Description - Plants rather robust, in somewhat stiff, lustrous, green, yellow-green, or brownish, loose tufts or mats. Stems ascending or erect, irregularly pinnately branched, the stem and branch apices cuspidate; in cross-section with a hyalodermis, over small thick-walled cells surrounding large thin-walled cells, central strand present, small; paraphyllia absent; pseudoparaphyllia foliose, large; axillary hairs with a single short brown basal cell and 2-5 elongate hyaline distal cells. Stem and branch leaves somewhat differentiated, the stem leaves appressed to stem, longer and relatively broader, branch leaves appressed to erect-spreading, all oblong-lanceolate to oblong-ovate, acute to obtuse, sometimes short-apiculate, concave, not plicate, auriculate; margins entire throughout or subdenticulate at apex, incurved or plane above, plane below; costa short and double or none; cells linear-flexuose, smooth, firm-walled, not at all or scarcely porose, becoming shorter, long-rectangular, and somewhat porose toward the insertion; alar cells conspicuously and abruptly differentiated in the auricles, hyaline, inflated, thin-walled. Asexual propagula none. Dioicous. Perichaetia conspicuous; leaves erect, linear to oblong-lanceolate, ± abruptly acute to short-acuminate, strongly plicate; margins entire or serrulate, especially at the shoulders, plane; costa none; cells linear, smooth, thick-walled, slightly porose, becoming shorter, broader, and thinner-walled toward the insertion. Setae very long, smooth, reddish; capsules inclined, arcuate, asymmetric, cylindric, wrinkled when dry; exothecial cells short-rectangular, thick-walled, ± collenchymatous; annulus differentiated in 2-4 rows, deciduous; operculum high conic-apiculate; exostome teeth shouldered, bordered, on the front surface cross-striolate below, coarsely papillose and hyaline above, trabeculate at back; endostome with a high basal membrane, segments keeled, narrowly perforate, cilia in groups of 2-4. Spores spherical, finely papillose. Calyptrae not seen (nor literature description found).
Discussion:Calliergonella Loeske, Hedwigia 50: 248. 1911, non (Cardot) Cardot & Broth., Kongl. Svenska Vetenskapsakad. Handl. 63(10): 67. 1923, hom. illeg. [= Catagonium Müll. Hal.]; Calliergon sect. Calliergonella (Loeske) Monk, in Rabenh., Rabenh. Krypt.-Fl., ed. 2, 4(Suppl. [Laubm. Eur.]): 744. 1927.
Calliergon subgen. Pseud-Acrocladium Kindb., Eur. N. Amer. Bryin. 1: 80. 1896 ; Acrocladium sect. Pseud-Acrocladium (Kindb.) Broth, in Engl. & Prantl, Nat. Pflanzenfam. 1(3): 1038. 1908, “Pseudo-Acrocladium.”
Discussion. Calliergonella is characterized by plants of wet habitats with cuspidate branch and stem tips. The leaves are often rounded at the apex, ecostate (or with a short and double costa), and with abruptly differentiated, hyaline, inflated alar cells. The stem hyalodermis is also distinctive.
Calliergonella was recently treated by Hedenas (1990b) and expanded to include Hypnum lindbergii Mitt. Although this species and Calliergonella cuspidata have exceedingly different aspects, the alar cells and capsule morphology are very similar. Hypnum lindbergii is not in the West Indies, though, and so a thorough evaluation has not been made.
Hedenas (1990b) tentatively followed Nishimura et al. (1984) in placing Calliergonella in the Hypnaceae. Recently, though, Hedenas (pers. comm., 1995) told me that he is unsure of its relationships. Calliergonella has nothing to do with Calliergon or Pseudo-calliergon. It can be easily separated by leaves with a short, double costa, the hyalodermis of the stem, and by strongly plicate perichaetial leaves. Because of the lack of careful study and because I am dealing with a taxon introduced to the West Indies, I am tentatively retaining Calliergonella in the Amblystegiaceae for the purposes of this flora.