From the Greek kalos (beautiful) and mnion (a moss).

Dioicous. Very slender mosses forming mats on trunks of tree ferns, yellowish green to orange-green. Stems short, erect, filiform, usually less than 10 mm tall, simple, arising from a persistent creeping protonema. Protonema a robust caulonema with pinnate to bipinnate filamentous yellowish green prostrate branches; cells verrucose. Leaves rudimentary, distant, fragile and caducous below, larger and more crowded above, in 3 rows (2 lateral and
1 dorsal), dimorphic; lateral leaves inserted transversely, patent, little-altered when dry, oblong to oblong-lanceolate, acute; dorsal leaves smaller, appressed, apiculate; laminal cells small, isodiametric, 4–6-sided, pellucid, smooth.

Perichaetia and perigonia terminal. Perigonia gemmiform. Perichaetial leaves longer, erect, narrowly oblong or linear-spathulate. Calyptra narrow, cucullate, papillose apically. Setae short, slender. Capsules ovate-cylindrical, erect, symmetrical, brown; mouth reddish; operculum with a long beak, inclined, more than half the length of the theca. Peristome absent.

This genus contains nine species: one in New Zealand and south-eastern Australia; one endemic to the southern South Island of New Zealand; and one each in Lord Howe Island, Samoa, French Polynesia, Vanuatu, New Caledonia, Ceram (Indonesia) and Norfolk Island, all closely similar, and almost always growing on the trunks of tree ferns.

Calomnion Hook.f. & Wilson, in J.D.Hooker, Fl. Nov.-Zel. 2: 97 (‘1855’) [1854]. Type: C. laetum Hook.f. & Wilson [= C. complanatum (Hook.f. & Wilson) Lindb.]

Taxonomic synonyms

Gymnostomum sect. Eucladon Hook.f. & Wilson, London J. Bot. 3: 538 (1844). Type: G. complanatum Hook.f. & Wilson [= C. complanatum (Hook.f. & Wilson) Lindb.]

Brotherus, V.F. (1924), Calomniaceae, Nat. Pflanzenfam., 2nd edn, 10: 422–424.

Goffinet, B., Shaw, A.J. & Buck, W.R. (2012), Classification of the Bryophyta. [http://www.eeb.uconn.edu/people/goffinet/Classificationmosses.html]

Sainsbury, G.O.K. (1955), A handbook of New Zealand mosses, Bull. Roy. Soc. New Zealand 5: 292–293.

Stone, I.G. (1990), Nomenclatural changes and new moss species in Australia; including a description of the protonema of Calomnion, J. Bryol. 16: 261–273.

Vitt, D.H. (1991), A new species of Calomnion (Bryopsida) from Lord Howe Island, Novon 1: 53–55.

Vitt, D.H. (1995), The genus Calomnion (Bryopsida): taxonomy, phylogeny, and biogeography, Bryologist 98: 338–358.

 D.G.Catcheside & G.H.Bell (2012), Australian Mosses Online 44. Calomniaceae. Australian Biological Resources Study, Canberra. Version 13 June 2012. http://www.anbg.gov.au/abrs/Mosses_online/44_Calomniaceae.html

First published as: D.G.Catcheside & G.H.Bell (2006), Calomniaceae, Fl. Australia 51: 367–368. Australian Biological Resources Study, Canberra & CSIRO Publishing, Melbourne.