Plagiochasma crenulatum Gottsche

Plagiochasma crenulatum Gottsche, Danske
Vid. Selsk. Skr. V. 6: 362. ~ 1863.
-Aytonia crenulata Underw. Bot. Gaz. 20: 66. 1895. Plagiochasma Muenchianum Stephani, Sp. Hep. 6: 9. 1917.
Thallus pale-green above but not glaucous, pigmented with purple below and along a narrow border above, mostly 1-3 cm. long and 5-10 mm, wide, with a broad rounded keel and undulate-crenate, more or less crispate margins, plane or broadly canaliculate on the upper surface; branching dichotomous and ventral, apical innovations lacking; epidermal cells about 30 M in diameter, with distinct trigones and a thin smooth cuticle; pores slightly elevated, surrounded by about 6 radiating series of cells with 2 or 3 cells in each series, the radial, walls slightly thickened; green tissue fairly compact; ventral scales purple, slightly imbricate, the appendages borne singly or rarely in pairs, broadly ovate, shortapiculate or abruptly acute, irregularly sinuatedentate, sharply dentate, or even lobate at the base. Autoicous; male receptacle borne on a short ventral branch; female receptacles borne singly or in tandem pairs, the stalk 1-1.5 cm. long, the disc concave or bluntly indented with 2 or 3 apiculate lobes, the paleae lanceolate to narrowly ovate, irregularly sinuate or with an occasional tooth; spores yellowish-brown, about 80 m in diameter, minutely verruculose, regularly reticulate, the meshes mostly 16-20 fi wide; elaters about 12 ju wide, mostly trispiral, the spirals often -coalescent along one side.
Type locality: Puebla, Mexico. Distribution: Mexico. ^