HASTINGS, ROXANNE I.* and DONNA M. CHERNIAWSKY. Provincial Museum of Alberta, 12845-102 Avenue, Edmonton, Alberta, Canada, T5N 0M6. - Species separation in the Grimmia longirostris-G. pilifera (Grimmiaceae) complex in North America.
Largely due to the use of relative differences, the separation of
species in the Grimmia longirostris-G. pilifera complex has
often proven problematic. Using character combinations of stem
anatomy, seta/capsule lengths, and sexuality we recognize four species
in the complex in North America and demonstrate that G.
arizonae and G. catalinensis, both lost in synonymy, are
good species. Grimmia pilifera typically has long, acuminate
apices with a short ovate base, short awns, and lacks a central strand
(Cao and Vitt 1986, Crum 1994, Greven 1999). Grimmia arizonae
has broader, ovate-lanceolate leaves, long awns, and a central strand.
However, Munoz (1999) synonymizes G. arizonae with G.
pilifera, dismissing their differences as a result of locality
variation and sexual development. He reports that in eastern North
America, and in shade, G. pilifera has its typical form.
However, in the west, and in sun, leaves are ovate-lanceolate without
distinct bases. To him, the absence of a central strand, is “too
variable to be reliable;” fertile stems have a distinct strand,
sterile stems have none. By contrast, we found no correlation between
sexual maturity and strand development; sterile or fertile G.
pilifera lack a central strand. Further, its stem epidermis is
consistently 2x thicker than G. arizonae. In the west there are
specimens without a central strand, long, acuminate apices and ovate
bases (G. pilifera) and others with a central strand, and
broadly ovate-lanceolate leaves (G. arizonae). Both Munoz and
Greven classify G. catalinensis as G. longirostris with
immersed capsules. However, specimens with long setae (G.
longirostris) are cladautoicous, while specimens with short setae
(G. catalinensis) are gonioautoicous. Thus we recognize four
species. Grimmia longirostris: cladautoicous, exserted
capsules, with a central strand. Grimmia catalinensis:
gonioautoicous, immersed capsules, with a central strand. Grimmia
arizonae: dioicous, immersed capsules, with a central strand.
Finally, G. pilifera: dioicous, immersed capsules, and no
Key words: central strand, Grimmia, Grimmiaceae, taxonomy