Dasygrammitis

Dasygrammitis is a genus of grammitid ferns known from Sri Lanka through southeast Asia and the Philippines to Polynesia.

Description

The rhizomes are radially symmetric (without distinct upper and lower surfaces) and bear whorls of stipes, which lack a joint at the point of attachment. The rhizome scales are red-brown, of uniform color, and usually glossy. They have unbranched, red-brown hairs on their edges.^[1]

Hairs, where present, are unbranched and branched, and brown in color. The leaf blades are usually pinnate in cutting rarely pinnatifid or bipinnatifid, bearing free veins which lack hydathodes at their terminus. Sori are borne in two rows beneath pinnae or lobes. The sori are circular to elliptic in shape; the sporangia either lack hairs or have one to two red-brown hairs.^[1]

Taxonomy

The genus was first described by Barbara Parris in 2007 to receive some of the species of the genus Grammitis, which as then circumscribed was artificial and contained a number of disparate lineages. The name "Dasygrammitis" means "shaggy Grammitis", referring to the shaggy hairs often present on the frond in this group of former Grammitis species. Parris placed six species in the genus:^[1]

• Dasygrammitis brevivenosa (Alderw.) Parris
• Dasygrammitis crassifrons (Baker) Parris
• Dasygrammitis fuscata (Blume) Parris
• Dasygrammitis malaccana (Baker) Parris
• Dasygrammitis mollicoma (Nees & Blume) Parris
• Dasygrammitis purpurascens (Nadeaud) Parris

A phylogenetic study of the grammitids found that Dasygrammitis was sister to a clade consisting of Calymmodon, Micropolypodium, Scleroglossum, Tomophyllum, and Xiphopterella.^[2] These six genera share a radially symmetric rhizome, which may be a synapomorphy for this clade (although the trait appears in other grammitid taxa, probably independently).^[1][2]

References