BFNA Title: Treubiaceae
XX. TREUBIACEAE Verdoorn
Alan T. Whittemore
Richard H. Zander
Plants terrestrial, bright green. Thallus with four rows of leaves, two lateral and two dorsal, branching dichotomous, seldom by lateral adventitious branches, without specialized conducting cells (but with a small-celled region in the middle of the thallus), underside without scales, without Nostoc colonies. Specialized asexual reproduction gemmae absent [multicellular]. Sexual condition dioicous [autoicous], gametangia scattered on dorsal surface of thallus; antheridia naked [in axils of dorsal leaves]; archegonia naked [in axils of dorsal leaves]. Sporophyte protected by protected by a massive calyptra. Capsule spherical, 4-valved; without fixed elaters; spores unicellular when shed, their walls thin and delicate.
Genera 2, species ca 8 (one genus and one species in the flora): B. C. (Queen Charlotte Islands), s Alaska; South America, Asia, Australia, Pacific Islands.
Treubiaceae is very isolated phylogenetically, and the structure of the gametophyte---a flattened axis bearing four rows of leaves---is quite different from that of any other liverwort.
1. APOTREUBIA S. Hattori& Mizutani, Bryologist 69 (4): 491. 1967
Thallus flattened, thick and fleshy, central region of narrow cells well-marked. Lateral leaves strongly succubous. Dorsal leaves with insertions strongly curved, lower toward stem middle, reaching midline of thallus. Oil-bodies confined to specialized cells, each with one large oil-body, scattered throughout the gametophyte. Sexual condition antheridia and archegonia naked, scattered on dorsal surface of thallus.
Species 1 (1 species in the flora): w North America, Asia.
SELECTED REFERENCE. Bakalin, V. and A. Vilnet. 2017. How many species are in Apotreubia S.Hatt. & Mizut. (Marchantiophyta)? Nova Hedw. 104(4): 473--482.
1. Apotreubia nana (S.Hattori & Inoue) S.Hattori & Mizutami, Bryologist 69: 492. 1967
Treubia nana S.Hattori & Inoue, J. Hattori Bot. Lab. 11: 99. f. a--o. 1954; Apotreubia hortoniae R. M. Schuster & Konstantinova ex Konstantinova
Thallus fleshy, pale yellow-green and speckled with white oil-bodies when fresh, shrunken and uniformly dark green when dry, mostly 1--1.7 cm long and 4--5 mm wide. Lateral leaves imbricate, rectangular or rhombic, 2.5--3 mm, apex obtuse, truncate or broadly and shallowly retuse, cells 26--32 x 39--42(--60) \mu. Dorsal leaves ovate, spreading and ± canaliculate when hydrated, crisped when dry. Specialized asexual reproduction not seen [by sessile multicellular gemmae sometimes produced on dorsal midline of thallus]. Sexual condition dioicous.
Scattered among other bryophytes, rarely forming dense colonies, on peat or humus, seldom rotting wood, in very wet habitats; sea level to 1000 m; B. C. (Haida Gwaii [Queen Charlotte Islands]), s Alaska; Asia.
The few North American collections are dioicous and lack gemmae. However, these characters are variable across the range of the species. Plants with the same characteristics as North American material can be found in Asia, and taxonomic separation of North American plants doesn't seem warranted (V. Bakalin and A. Vilnet 2017). The lack of variation in North America may be due to the sparse sampling.