Riccia ekmanii S.W.Arnell

  • Authority

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

  • Family

    Ricciaceae

  • Scientific Name

    Riccia ekmanii S.W.Arnell

  • Type

    Type. Cuba. Prov. Oriente, Daiquiri, Ekman 8432 (holotype, S).

  • Description

    Species Description - Thalli in gregarious patches; lobes 2-3 times forked, 8-10 mm long, 1.5-3 mm wide; dorsal side greenish, flattened and slightly concave when dry, rounded apically, margins acute, slightly undulate, hyaline and dotted with pink-violet. Median groove deep apically, shallower and vanishing below. Epidermal cells disintegrating except apically, convex. Ventral scales imbricate, entire, hyaline, dotted with pink-violet near margins, or entirely pink-violet, reaching or extending beyond lobe margins. Cross section of lobes 4-4.5 times as wide as high; dorsal edge acute laterally; flanks obliquely ascending, outer layer of larger cells than those of ventral tissue, tinged with pink-violet, with 1-2 hyaline cells apically; ventral edge convex; dorsal tissue in 3-5 cell layers, cells with 2 thickened, longitudinal strips. Monoecious. Antheridial necks colorless. Archegonial necks long, violaceous. Sporangia bulging mainly on ventral side. Spores tetrahedral, 90-120 |im diam., red-brown, wingless, margins weakly crenulate; distal face with (6-)8-9 areoles across diam., with thick, red-black ridges and large tubercles; proximal face with short ridges and tubercles of varying size and shape, ridges of triradiate scar discontinuous.

  • Discussion

    Riccia ekmanii is close to R. weinionis and R. ridleyi. It is characterized by hyaline lobe margins, dotted with violet at level of insertion of the scales. Its spores have 6-9 areoles across the diam, on the distal face, as in R. weinionis (not 10-12 as in R. ridleyi). The facets of the proximal face show 10-12 areoles in R. weinionis, whereas in R. ekmanii they are more numerous and ill-delimited, with short, discontinuous ridges and tubercles of variable size and shape.

  • Distribution

    The sole specimen known of this species was collected on a coral reef exposed to salt water spray.

    Cuba South America| Oriente Cuba South America|