Radula kegelii Gottsche ex Steph.

  • Authority

    Gradstein, S. Robbert & Ilkiu-Borges, Anna L. 2009. Guide to the plants of Central French Guiana. Part 4. Liverworts and hornworts. Mem. New York Bot. Gard. 76 (4): i-iv + 1-140.

  • Family

    Radulaceae

  • Scientific Name

    Radula kegelii Gottsche ex Steph.

  • Description

    Species Description - Plants 1.5-2 mm wide, pale olive-green, loosely creeping to pendent, irregularly pinnate to subdichotomous, gynoecial portions of plants dichotomous due to paired innovations. Leaf lobes subimbricate, widely spreading, ovate, not falcate, apex rounded, dorsal base not or slightly arching beyond stem. Cells in midlobe subisodiametrical, small, ca. 15-20 µm in largest diameter, thin-walled, trigones small cuticle smooth. Lobules relatively small, ca. 1/4 of lobe length, distant, spreading at an angle of ca. 60° with stem, subquadrate to asymmetrically broad-rectangular, somewhat inflated along keel, the keel straight or curved-concave, apex obtuse, not elongate, antical margin usually wavy, base covering 1/4-1/2 of stem. Vegetative reproduction lacking.

  • Discussion

    Radula kegelii is common and widespread at lower elevations in tropical America. Characteristic of R. kegelii are the small leaf cells, averaging 15-20 µm in diameter in midleaf. The lobules are rather small as well, and their bases are often hardly auriculate, especially in male plants (e.g., Holz 328, identified by K. Yamada as R. mazaru- nensis). Although considered a member of the section Dichotomae, vegetative branching in Radula kegelii is normally irregularly pinnate instead of dichotomous (Reiner-Drehwald, 1994). In gynoecial portions of the plants, however, branching may be regularly dichotomous due to repeatedly fertile, paired innovations. Radula kegelii was first described in 1884; earlier collections of R. kegelii were usually named R. pallens (Swartz) Dumortier, which according to Castle (1960) is a more robust plant. Because branching in both species is pinnate, relationships between R. pallens and R. kegelii should be reconsidered; the two may be conspecific. In that case, the name R. pallens should replace R. kegelii.