Monographs Details: Plagiochasma crenulatum Gottsche
Authority: Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)
Synonyms:Aytonia crenulata (Gottsche) Underw.
Description:Species Description - Thallus 5.3-6.7 mm wide, light or yellowish green, with red or purplish, narrow margins. Apical adventitious branches infrequent. Epidermis smooth, epidermal cells 31-40 × 24-28 µm, walls usually with large, nodulose trigones. Epidermal pores 2766 per mm2, slightly raised above epidermis, 21-24 µm diam., bounded by 2-3 concentric rings of 6-7 (-8) cells with slightly thickened radial walls. Ventral scales purplish, bordered by 2-3 rows of light-red or hyaline, sinuose cells; appendage 1, rarely 2, ovate or rounded, hyaline, sometimes light red or yellowish in the central part, length/width ratio 0.8-1.3:1; obtuse, acute or apiculate apically, largest in the middle, 22-26 cells wide, constricted and plicate basally, margins crenulate or toothed, with several rows of sinuose cells, some with papillae. Male receptacles dorsal, usually reniform, with 20-25 antheridia. Scales of male and female receptacles hyaline or partly purplish, acute or apiculate, with crenulate or remotely toothed margins. Archegoniophores dorsal, stalk 0.8-5 mm long, with thickened, red or brown epidermal cells. Involucres 1-3, yellow, purplish or brown. Spores 70-78 µm diam., dark yellow or brown, areolate; areoles and ridges tuberculate. Elaters with 2-4 helical bands. Gametophytic chromosome number n = 18.

Discussion:Plagiochasma crenulatum is a polyploid species. It is distinguished from other neotropical species by the wide, rounded or ovate appendages of the ventral scales.
Distribution:Veracruz Mexico North America| San Luis Potosí Mexico North America| Querétaro Mexico North America| Hidalgo Mexico North America| Morelos Mexico North America| Nuevo León Mexico North America| Oaxaca Mexico North America| Sonora Mexico North America| Puebla Mexico North America| Alta Verapaz Guatemala Central America| Izabal Guatemala Central America| Comayagua Honduras Central America|