Guide to Liverworts of Oregon: Macrodiplophyllum rubrum D.H. Wagner
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Diplophyllum 1a leaves decurrent > Macrodiplophyllum rubrum
Synonyms: none.
Misapplied names: Diplophyllum plicatum Lindb.; Macrodiplophyllum plicatum (Lindb.) Persson; Scapania plicata (Lindb.) Potemkin; Douinia plicata (Lindb.) Konstant. et Vilnet
Special Status: Formerly listed as a sensitive species (under Diplophyllum plicatum) but dropped because of the number of records in the Coos Bay District of BLM.
Recognition: A large species with two rows of bilobed leaves. The lobes are long, angled away from the stem, and folded over each other. The upper, dorsal lobe is the smaller one. This species stands out from its most common associate, Scapania bolanderi, by its pale green color. In the field the decurrent, dentate, wine red ventral leaf base is distinctive; to the naked eye it looks like a wavy red line running down the underside of the stem just below the apex. There is a central band of elongated cells, called a vitta, near the base of each lobe. It is not easily seen in the field with a hand lens but is unmistakeable when viewed with a compound microscope. The much more common Diplophyllum albicans also has a vitta which is much more distinct than that of Macrodiplophyllum rubrum. Diplophyllum albicans is usually found on soil while Macrodiplophyllum rubrum is always on organic substrates, typically near the base of tree trunks.
Distribution: On bark, mostly of conifers but also hardwoods; along the coast and inland a short distance. Reported from Clatsop, Coos, Douglas, Lane, Lincoln and Tillamook Counties. First Oregon collection (apparently): Seaside, Clatsop County, on Picea sitchensis. 1 Sept 1898. F.V. Coville 851. (UC; verified D. Wagner 1983.)
Another previously unrecognized species, Macrodiplophyllum flaccidum D.H. Wagner, was described recently (Wagner 2016). It is not in key to species here but is discussed separately [CLICK HERE to visit its species page]. It barely reaches Oregon, presently known only from Saddle Mountain in Clatsop County.
Comments: There are more records in Coos County than any other county.
Diplophyllum plicatum was placed in Scapania by Potempkin (1999). In my view this species is clearly more closely related to Diplophyllum rather than Scapania and would be better treated in Macrodiplophyllum. The plants found in Oregon are not the same species as M. plicatum and have been recently described as a new species, Macrodiplophyllum rubrum D.H. Wagner (Wagner 2016).
Macrodiplophyllum is distinguished by its robust character, rounded, long lingulate leaf lobes, elongated basal cells, arcuate and decurrent ventral lobe, and plicate perianth, usually to the base, with a constricted mouth. It is a natural group characterized by an array of ancestral traits rather than strict phylogenetic lineage. Phylogenetic analysis shows that Macrodiplophyllum is derived from the more generalized genus Diplophyllum and is basal to two more specialized genera, Douinia and Scapania. Alternate classifications would place the known species of Macrodiplophyllum in Diplophyllum (Hong 1980; Steere 1978), all in Scapania (Potemkin 2002), or divide its species between Scapania and an enlarged Douinia (Konstantinova et al. 2013). Until the two new species, Macrodiplophyllum rubrum and M. flaccidum, are subjected to molecular analysis their position in phylogenetic trees cannot be used to evaluate alternate classifications in Scapaniaceae.
Macrodiplophyllum rubrum, in situ on log. Cape Perpetua, Lincoln County, Oregon. DHW field photo.
Cape Perpetua, Lincoln County, Oregon. DHW photo.
Dorsal aspect, dry specimen in air. King Island, British Columbia, Canada. W. Schofield W86243 (UBC).
Ventral aspect, dry specimen in air. King Island, British Columbia, Canada. W. Schofield W86243 (UBC).
Macrodiplophyllum rubrum. Haida Gwaii, British Columbia, Canada. Des Callaghan 25 May 2023. (With permission).
Dorsal aspect, water mount. Cape Perptua, Lincoln County, Oregon. DHW m3006.
Ventral aspect, water mount. Cape Perptua, Lincoln County, Oregon. DHW m3006.
Dorsal aspect, moist shoot, dry mount, gemmiferous shoot tip. Cherry Creek RNA, Coos County, Oregon. DHW m3014 (Type).
Leaf outline, ventral view. Lake 22 trailhead, Snohomish County, Washington. L.Russell 27 March 1979.
Ventral lobe basees. Cape Perpetua, Lincoln County, Oregon. DHW m3006.
Cherry Creek RNA, Douglas Co., Oregon. DHW 9051.
Ventral lobe base. Cherry Creek RNA, Coos County, Oregon. DHW m3014 (Type).
Gemmae on leaf margin, with blue stain. Cherry Creek RNA, Douglas Co., Oregon. DHW 9051.
Leaf marginal cells. Cape Perpetua, Lincoln County, Oregon. DHW m3006.
Oil bodies in midleaf cells. Cape Perpetua, Lincoln County, Oregon. DHW m3006.
Oil bodies in midleaf cells. Cherry Creek RNA, Coos County, Oregon. DHW m3014 (Type).
Oil bodies in lower leaf cells. Cape Perpetua, Lincoln County, Oregon. DHW m3006.
Oil bodies in leaf base cells. Cape Perpetua, Lincoln County, Oregon. DHW m3006.
Oil bodies in cells at leaf base. Cherry Creek RNA, Douglas Co., Oregon. DHW 9051.
Female bract with included bractlet. Goodman Creek, Jefferson County, Washington. DHW m1120.
Bractlet isolated from female bract. Goodman Creek, Jefferson County, Washington. DHW m1120.
Perianth dissected from female shoot tip. Goodman Creek, Jefferson County, Washington. DHW m1120.
Perianth mouth. Goodman Creek, Jefferson County, Washington. DHW m1120.
Stem section. Cape Perpetua, Lincoln County, Oregon. DHW m3006.