GRIMMIA ARCUATIFOLIA AND G. LEIBERGII (MUSCI, GRIMMIACEAE), TWO NEGLECTED SPECIES FROM NORTHWESTERN NORTH AMERICA

MUÑOZ, J. (1999). Grimmia arcuatifolia and G. leibergü (Musci, Grimmiaceae), two neglected species from Northwestern North America. Anales Jard. Bot. Madrid 57(1): 7-13. Grimmia arcuatifolia and G. leibergü are recognized as distinct species. Each is known from restricted áreas in northwestern North America. Grimmia alternuata and G. procera are synonyms of G. arcuatifolia.


INTRODUCTION RESULTS
In the list of mosses of continental USA and Canada, ANDERSON & al. (1990) recognized 36 Grimmia taxa.ALLEN (1995) evaluated seven species of Grimmia previously neglected, all of which were found to be the same as described species.Revisionary work by MUÑOZ (1998aMUÑOZ ( , 1998b) ) has shown that G. caespiticia (Brid.)Jur. and G. ungeri Jur. are present in North America, and changed the status of previous ñames.

Grimmia arcuatifolia
Habitat.On exposed rocks and cliffs.Further data unavailable.
Grimmia arcuatifolia is a robust species with long, nearly unbranched, ascendent stems, a ± reniform costa 4-6(8) cells-wide on the ventral side, smooth capsules, cygneous setae, and triangular, entire peristome teeth.Grimmia elatior, a similar species known from the same área, approaches G. arcuatifolia in its robust habit, ascendent and nearly unbranched stems, cygneous seta, and entire peristome teeth.However, in G. elatior the costa is 2 cells-wide in the ventral band and irregularly furrowed dorsally, the capsules ribbed, and most populations have strongly bulging, papillose leaf cells.
Specimens agreeing completely with the protologue of G. arcuatifolia have not been found, a problem experienced also by FRISVOLL (1988:228).A further complication is that most of the specimens identified as G. arcuatifolia by Kindberg or Macoun are other species, principally Racomitrium heterostichum (Hedw.)Brid.The only specimen in S that is G. arcuatifolia does not match the protologue, either by locality or date, although it might be part of the original collection.Thus, I pcefer to select as lectotype a specimen in CANM that most closely approaches the protologue.

On granite. Further data
Grimmia leibergii is characterized by its prostrate to ascending Racomitrium-üke habit, unistratose lamina, margins recurved for more than half the lamina length, fíat hair-points, reniform costa 4-6 cells wide, dioicous sexual condition, ribbed capsules, and cygneous setae.It has a decided Racomitriumlike macroscopic appearance, but leaf areolation and sporophyte characters indícate Grimmia as the correct genus for the species (see discussion under G. arcuatifoliá).
Grimmia leibergii is sharply distinct from any other species in the genus, and it is surprising that it has not been considered worthy of recognition except by JONES (1933: 40), who treated G. leibergii as an independent taxon although he expressed doubts about its distinction from G. decipiens (Schultz) Lindb.Jones stated that G. leibergii would be identical with G. decipiens except for its dioicous sexual condition and annulus structure.However, besides differences in its sexual condition, G. decipiens has erect stems, terete hair-points, and the lamina is partially to totally bistratose, not just at the margins as in G. leibergii.
Subsequently, LAWTON (1971: 133) studied the type of G. leibergii and discussed its relationships with G. decipiens and G. trichophylla Grev.She concluded that it was distinct from G. decipiens but not from G. trichophylla, from which she considerad G. leibergii merely a form.This decisión was accepted by CRUM & al. (1973: 116).Lawton based her conclusions on variability in costal structure of the type of G. leibergii, which, according to her, showed intermediates with typical G. trichophylla.I agree with the differences between G. leibergii and G. decipiens stated above, but I do not see the supposed intergradation in costa structure between collections of G. leibergii and G. trichophylla.Grimmia trichophylla differs from G. leibergii in being a much smaller plant with a different habit, having erect stems, terete hair-points, and a semiterete costa with two ventral cells as seen in cross sectíon.