Plagiochasma landii A.Evans

  • Authority

    Bischler, Hélène, et al. 2005. Marchantiidae. Fl. Neotrop. Monogr. 97: 1--262. (Published by NYBG Press)

  • Family

    Aytoniaceae

  • Scientific Name

    Plagiochasma landii A.Evans

  • Type

    Type. Mexico. Morelos: W of the city of Cuernavaca, Barnes & Land 466 (holotype, YU; isotypes, FH, NY).

  • Description

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    Species Description - Thallus 4.4-5 mm wide, yellowish green, often partly tinged with purple, with narrow, purplish margins; apical adventitious branches frequent, often long. Epidermis smooth; epidermal cells 33-35 × (21-)24-28 µm, with medium-sized or large, sometimes nodulose trigones. Epidermal pores 8-20 per mm2, raised above epidermis, 14-24 µm diam., bounded by 2-3(-4) concentric rings of 6-8(-10) cells, radial walls strongly thickened. Scales purplish or orange, with border of 1-2 rows of light-red, sinuose cells; appendages (1-)2-3, narrowly triangular, apex acuminate and acute, with row of 1-2 cells apically, light red or purplish, rarely hyaline, widest basally, 12-15 cells wide, not constricted or plicate, length/width ratio 3-4:1; margins often with some teeth, without papillae. Male receptacle usually at base of apical adventitious branches, rounded or reniform, with 20-30 antheridia. Scales of male and female receptacles hyaline, or partly tinged with purple, acute, with row of 2-3 cells apically, margins often toothed and with scattered papillae. Archegoniophores dorsal, stalk 0.2-0.4 mm long, with thickened, dark-purplish epidermal cells. Involucres 2-3, light brown or purplish. Spores 82-100 µm diam., light or dark brown, with complete or incomplete areoles on both faces, ridges ± densely tuberculate. Elaters with 2-4, sometimes interrupted helical bands. Gametophytic chromosome number unknown.

  • Discussion

    Although considerable variation is observed in the shape and structure of the scale appendages, in elater structure, and in spore wall ornamentation, this species cannot be split into morphologically well-characterized groups. Plagiochasma landii is most closely related to P. cuneatum and P. argentinicum and is separated from these 2 species by the smooth epidermis.

  • Distribution

    Plagiochasma landii is an uncommon New World species distributed from 23°5’N to 11°N, known from southern U.S.A (Texas), Mexico (Chiapas (Bourrell, 1992), D. F., Morelos, San Luis Potosi), Guatemala, and Costa Rica. It has been collected in rock crevices in exposed or partly shaded habitats, in relatively dry areas between 1500 and 2850 m.

    San Luis Potosí Mexico North America| Distrito Federal Mexico North America| Morelos Mexico North America| Cartago Costa Rica Central America| Quezaltenango Guatemala Central America|