M. reptans (Hedw.) Card., Rev. Bryol. 40: 21. 1913.
Hypnum reptans Hedw., Sp. Muse. 265. 1801.
Chryso-hypnumpendulinum Hampe, Bot. Zeitung 28: 52. 1870.
Eurhynchium mexicanum Besch., Mem. Soc. Sci. Nat. Cherbourg 16: 248. 1872.
Microthamnium mexicanum (Besch.) Jaeg., Ber. Thatigk. St. Gallischen Naturwiss. Ges. 1876-77: 426. 1878.
Stereohypnum reptans (Hedw.) Fleisch., Hedwigia 47: 275. 1908.
Mittenothamnium mexicanum (Besch.) Card., Rev. Bryol. 38: 42. 1911.
M. pendulinum (Hampe) Card., Rev. Bryol. 40: 21. 1913.
Mittenthamnium reptans, the type species ofthe genus, is distinguished from other Mexican species by broadly triangular-ovate stem leaves with cells projecting only at the upper angles, and autoicous sexuality. This very common species is extremely variable in size, mode of foliation, shape of capsules, and length ofthe beak ofthe operculum, but the broadly triangular-ovate stem leaves and narrow branch leaves as well as the features of leaf areolation are rather constant.
In tropical America, many other species seem to be obscurely distinguished from M . reptans by such unreliable characters as size of plants, mode of foliation, and shape of capsules.