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127 Tropical Bryology 2: 127-132, 1990

Floristics of the South American Páramo Moss Flora Dana Griffin, III Department of Botany & The Florida Museum of Natural History, University of Florida, Gainesville, Florida 32611

Abstract. The South American paramos appeared in Pliocene times and persist to the present day. The moss flora of this habitat consists of an estimated 400 species that comprise 8 floristic groups. In Venezuela these groups and their percent representation are as follows: neotropical 37%, Andean 26%, cosmopolitan 18%, Andean-African 8%, neotropical-Asiatic 3%, neotropical-Australasian 2%, temperate Southern Hemisphere 2% and northern boreal-temperate 2%. Acrocarpous taxa outnumber pleurocarps by nearly 3:1. The neotropical and Andean floristic stocks likely were present prior to late Pliocene orogenies that elevated the cordillera above climatic timberlines. These species may have existed in open, marshy areas (paramillos) or may have evolved from cloud forest ancestors. Taxa of northern boreal- temperate affinities, including those with Asiatic distributions, probably arrived in the paramos during the Pleistocene, a period which may also have seen the establishment in the Northern Andes of some cosmopolitan elements. Species with temperate Southern Hemisphere and Australasian affinities likely spread first to austral South America thence migrated northward during a cool, moist interval sometime over the past 2.5-3 million years or may have become established in the paramos as a result of long- distance dispersal.

Reconstructing a floristic history for the pollen of Andean forest taxa. The páramo mosses of South America requires establishment of this chronology for the addressing a number of questions. When páramo habitat has important implications did the páramo life zone appear and for floristic reconstructions since it sets the supposedly become available to time frame within which the earliest colonizing species? Here we can be rather colonists must have arrived. It does not precise. From the pioneering work of establish; however, where the páramo Thomas van der Hammen and his moss species (or their antecedents) were coworkers (cf. van der Hammen 1974; in the period prior to the development of a van der Hammen & Cleef 1983, 1986), it páramo system (although we can speculate is clear an upper elevational timberline did on this point) nor does it tell us exactly not develop in the Northern Andes before how old a particular páramo species is. late Pliocene time (ca. 2-4 million years B.P.). The development of a páramo What are the broad outlines of the páramo system is revealed by a study of pollen moss flora? Here again, we are in a position deposited in lake sediments and is signa- to give a fairly detailed answer. led by a sharp rise in the frequency of Accelerated field work over the past 25 pollen types assignable to the Poaceae and years in the principal páramo countries of Asteraceae and a concomitant decrease in Ecuador, Colombia and Venezuela has 128 brought into herbaria thousands of fresh Colombia or Ecuador, a distinction that collections a majority of which have been will undoubtedly be reflected in the parti- identified at least to the level of genus. cular percent representation of the Much of this identification work remains following floristic groups in those to be published, but, in general terms, we countries. can observe that the páramo moss flora is distributed among approximately 45 The diverse nature of the páramo flora in families, 120-140 genera and Venezuela can be appreciated from the approximately 400 species. The great ma- fact that while this habitat occupies 4,100 jority of the species belong to acrocarpous square kilometers (Jahn 1931), it represents groups. Acrocarpy appears to be favored less than 1% of the Venezuelan national over pleurocarpy in exposed environments territory yet supports 39% of the total as a check of some selected floras confirms. known moss flora for the country. There For the following floras an acrocarp/ are approximately 700 species of Musci in pleurocarp ratio is given (numbers Venezuela (Griffin 1975, 1977a, 1977b, represent percent of total flora) along with 1979; Griffin, Lopez & Ruiz-Teran 1973; the references consulted: Alaskan tundra Pursell 1973) of which 272 (Griffin, this 75/25 (Steere 1978), alpine zone of Mexico paper) have been found above timberline 93/7 (Delgadillo 1971, 1979, 1982, 1984, in the Venezuelan Andes. 1986, 1987), páramos of Costa Rica 67/ 33 (Bowers 1974), páramos of Venezuela The páramo moss flora of Venezuela can 72/28 (Griffin, this paper), Antarctica 81/ be partitioned into 8 floristic groupings. 19 (Robinson 1972). Vitt (1979) reported These are (with percent representation): a preponderance of acrocarpous taxa in neotropical (37%), Andean (26%), polar floras of both hemispheres and in the cosmopolitan (18%), Andean- African temperate floras of the Southern (8%), neotropical-Asiatic (3%), Hemisphere with a shift toward more neotropical-Australasian (2%), temperate pleurocarpous species in tropical floras Southern Hemisphere (2%) and northern and those of temperate latitudes in the temperate/boreal (2%). Northern Hemisphere. While valid as generalizations, these trends can change Neotropical Element for more localized regions or habitats. I This component of the páramo flora believe the more universal correlative is consists of those taxa of wide distribution degree of exposure (i.e., likelihood of in the neotropics. Few, if any, are restricted periodic drying), regardless of which to habitats above timberline and likely hemisphere is examined. Forested areas were present before the appearance of a tend to support pleurocarp-rich floras, as páramo life zone. These species evidently seen in the case of the Great Lakes area 53/ were preadapted to surviving under the 47 (Crum 1976) or Mont Bokor, more stressful conditions of the páramo Cambodia 41/59 (Tixier 1979), whereas environment. Included in this element are relatively treeless areas appear to favor species found in forests, forest clearings acrocarps. and savannahs. Some representatives of this group are: Sphagnum meridense The high elevation moss flora of Venezuela (Hampe) C. Müll., S. sparsum Hampe, has been studied in some detail, and it can Fissidens repandus Wils., Ditrichum be used as a model for discussing floristic rufescens (Hampe) Broth., Campylopus groups throughout the Andean páramo heterostachys (Hampe) Jaeg., Pilopogon life zone. It should be recognized; however, gracilis (Hook.) Brid., Bryoerythrophyl- that the Venezuelan páramos are lum jamesonii (Tayl.) Crum, Entosthodon comparatively drier than those found in jamesonii (Tayl.) Mitt., Bryum 129 beyrichianum (Hornsch.) C. Mül., Bryum chadelphus ciliatus (Hook. f. & Wils.) grandifolium (Tayl.) C. Müll., Pohlia Mitt. papillosa (C. Müll. ex Jaeg.) Broth., Bartramia potosica Mont., Ptychomitrium Cosmopolitan Element chimborazense (Mitt.) Jaeg., Macromi- trium guatemalense C. Müll., The cosmopolitan element of the páramo Orthotrichum pycnophyllum Schimp., moss flora contains a diverse assortment Zygodon pichinchensis (Tayl.) Mitt., of species which, while sharing Lepyrodon tomentosus (Hook.) Mitt., multicontinental distributions, are Porotrichum longirostre (Hook.) Mitt., otherwise very different. The time of their Daltonia gracilis Mitt., Rigodium toxarion appearance in the páramos and the migra- (Schwaegr.) Jaeg., Brachythecium tory tract by which they arrived are virtually stereopoma (Spr. ex Mitt.) Jaeg., impossible to ascertain. Some were surely Plagiothecium conostegium Herz., present prior to the development of the Catagonium brevicaudatum C. Müll. ex páramos, others may have arrived by long- Broth., Aptychella proligera (Broth.) distance dispersal while still others Herz., Sematophyllum swartzii undoubtedly came in stages utilizing (Schwaegr.) Welch & Crum and Hypnum stepping stone habitats that must have amabile (Mitt.) Hampe. been available during the period of the Pleistocene. Included in this group are Andean Element species which produce sporophytes readily This is a montane component which, like and others for which only gametophytes the neotropical element, most likely was are known. Some representatives are: in place before the appearance of the Sphagnum magellanicum Brid., Andreaea páramo habitat. As such, most of these rupestris Hedw., Fissidens asplenioides species occur in Andean forests as well as Hedw., Ceratodon stenocarpus BSG, páramos. Some typical members of the Distichium capillaceum (Hedw.) BSG, group are: Pleuridium andinum Herz., Campylopus flexuosus (Hedw.) Brid., An- Campylopus argyrocaulon (C.M.) Broth., oectangium aestivum (Hedw.) Mitt., Campylopus cucullatifolius Herz., Kin- Didymodon vinealis (Brid.) Zander, giobryum paramicola H. Robins., Grimmia ovalis (Hedw.) Lindb., Funaria Oreoweisia tunariensis Herz., Aloinella hygrometrica Hedw. var. calvescens venezuelana Griffin, Leptodontium (Schwaegr.) Mont., Anomobryum filifor- erythroneuron Herz., L. stellaticuspis me (Dicks.) Husn., Bryum argenteum Bartr., Racomitrium steerei Griffin, Hedw., Bryum billardieri Schwaegr., Splachnum weberbaueri Reimers, Aulacomnium palustre (Hedw.) Tayloria rubicaule A. Kop., Acidodontium Schwaegr., Philonotis hastata (Dub.) Wijk heteroneuron (Mitt.) Broth., & Marg., Orthotrichum rupestre Schizymenium pseudopohlia Shaw, Schwaegr., Hedwigia ciliata (Hedw.) P.- Bartramia humilis Mitt., Macromitrium Beauv., Calliergon sarmentosum (Wahl.) trachypodium Mitt., Orthotrichum grande Kindb., Pleurozium schreberi (Brid.) Mitt., Lewinsky, Racopilum intermedium Hypnum cupressiforme Hedw. var. Hampe, Braunia laxifolia Herz., lacunosum Brid. and Polytrichum Papillaria penicillata (Dozy & Molk.) juniperinum Hedw. Broth., Neckeradelphus obtusifolius (Tayl.) Steere, Daltonia latolimbata Andean-African Element Broth., Callicostellopsis meridensis (C. Müll.) Broth., Hookeriopsis steerei Griffin, This suite of species includes those disjunct Brachythecium herzogii Broth., Pogona- between the Andes (and, in some cases, tum andinum (Hampe) Mitt. and Polyti- other neotropical montane habitats) and 130 Africa. There is reason to believe that origin for these elements with subsequent these taxa do not represent a single floristic migration to the New World (cf. Hong element in the sense of sharing the same 1983; Sharp 1966, 1972). This migrational history. This can be surmised presumption may or may not be valid for by considering the details of their mosses, but, to the extent that this scenario distribution, especially in Africa. A spe- is plausible, it could be suggested that the cies like Brachymitrion jamesonii Tayl., Asian component of the present day pára- known from several localities in the Andes, mo flora migrated first to North America, but in Africa apparently restricted to Mt. likely prior to the Pliocene when climatic Cameroon, may be presumed to have had conditions would have been more a different floristic history from that of amenable to the migration of species Aongstroemia julacea (Hook.) Mitt., a requiring cool, moist environments and high elevation species in the neotropics, then, in stages, southward onto the South but found in several areas of Southern American mainland. As in the case of Africa and on nearby Indian Ocean is- some vascular plant species, several of the lands at relatively moderate elevations. Musci with this distribution pattern have However, until more information is disappeared from the north temperate part available concerning the history, complete of their New World range. Conceivably, distribution and ecology of these species, although less likely, a few Asian- they will continue to be treated as a single, neotropical disjunctions may have come if heterogeneous, floristic unit. Specific about by long-distance dispersal. Almost examples are: Aongstroemia julacea all of the taxa included in this group have (Hook.) Mitt., Campylopus chrismarii (C. retained their taxonomic uniformity throug- Müll.) Mitt., Campylopus jamesonii hout their range, both Old World and New (Hook.) Jaeg., Leptodontium World. One exception is Rozea which has capituligerum C. Müll., L. luteum (Tayl.) developed different but related species on Mitt., Streptopogon calymperes C. Müll. the two continents (Buck and Crum 1976). ex Geh., Brachymitrion jamesonii Tayl., The relevant taxa are: Aongstroemia Bryum ellipsifolium C. Müll., Schizyme- orientalis Mitt., Bryoerythrophyllum nium campylocarpum (Hook. & Arn.) recurvum (Griff.) Saito, Plagiomnium Shaw, Diplostichum longirostre (Brid.) rhynchophorum (Hook.) T. Kop., Mitt., Breutelia tomentosa (Brid.) Jaeg., Steerecleus serrulatus (Hedw.) H. Robins., Prionodon densus (Hedw.) C. Müll., Pseudotaxiphyllum distichaceum (Mitt.) Zelometeorium patulum (Hedw.) Manuel, Iwats., Pylaisiella falcata (BSG) Ando Palamocladium leskeoides (Hook.) Britt. and Rozea spp. and Pogonatum oligodes (C. Müll.) Mitt. Neotropical-Australasian Element Neotropical-Asiatic Element This disjunct floristic group includes those This relatively minor component of the species with an amphi-South Pacific páramo moss flora encompasses those distribution, occurring in Southeastern species occurring on the Asian continent Australia/New Zealand and in the Andes (and/or offshore islands) and in the of South America. Such disjunctions may neotropics. In the New World part of their be artifacts of plate separation or of long- range they are found typically at mid to distance transport of viable propagules. If upper elevations. Among some who have continental drift was a factor, then we are examined certain vascular plant species obliged to either assign an age of over 100 with similar amphi-North Pacific distribu- million years to the species involved or tions there seems to be a presumption presume that the modern disjuncts were favoring an Asian, or, at least, Old World derived from ancestral stock, but since the 131 species discussed here have not diverged Venezuelan páramos, most probably as a sufficiently in the two disjunct parts of consequence of the relative dryness of the their range to be distinguishable páramo life zone in Venezuela compared taxonomically, in spite of the considerable with that of Colombia or Ecuador. For time elapsed since plate separation, it seems Venezuela the species to be noted include: more attractive to posit long-distance Blindia magellanica Schimp. in C. Müll., transport of spores as the operative agent. Entosthodon laxus (Wils. in Hook. f.) Recent laboratory experiments on spore Mitt., Bryum andicola Hook. in Kunth, viability under various conditions of Conostomum pentastichum (Brid.) Lindb., storage (cf. van Zanten 1978, 1983, 1984) Amphidium tortuosum (Hornsch.) H. tend to support the hypothesis that the Robins. and Rhacocarpus purpurascens spores of some high latitude moss species (Brid.) Par. of the Southern Hemisphere could survive transport across oceanic distances. The Northern Temperate/Boreal Element species of interest in the present context are: Andreaea nitida Hook. f. & Wils., The moss species belonging to this element Fissidens rigidulus Hook. f. & Wils., have wide distributions at temperate and/ Dicranella cardotii (R. Brown ter.) Dix., or boreal latitudes in the Northern D. hookeri (C. Müll.) Card. and Hemisphere. They show diminished Entosthodon acaulis (Hampe) Fife. abundance and lower frequency of occurrence southward. At low latitudes Temperate Southern Hemisphere they are restricted to high elevation Element habitats. A few of these species have penetrated the Old World tropics and all The temperate Southern Hemisphere are found in the South American páramos. element of the páramo flora represents a group with highly interrupted ranges at The most likely time for the southward high austral latitudes. This assembladge extension of these northern species would has been called the antipodal element by have been during one or more Pleistocene some authors. Species with this type of glacial maxima. During these periods there distribution tend to occur on one or more was a boreal-like climate as far south as of the subantarctic islands, on Tasmania Northern Mexico and the Gulf coast of the and the extreme Southeastern corner of United States. In addition, the receiving mainland Australia and in the Patagonia- area in the Northern Andes was much Fuegian area of South America. Individual enlarged, expanding the total potential species may be absent from one or more of area in which a colonizing population these isolated stations, but there is a certain could become established. Included in continuity to the overall ranges of all this element are: Philonotis cernua (Wils.) members of the group. If hepatics are Griffin & Buck, Meesia triquetra (L.) considered along with Musci, the number Aongstr., Rhytidium rugosum (Hedw.) of these disjuncts in the Northern Andes Lindb., Calliergon trifarium (Web. & exceeds 30 species (Griffin, Gradstein & Mohr.) Kindb. and Scorpidium Aguirre 1982). The Northern Andes scorpioides (Hedw.) Limpr. represent, for many, the extreme northern limit of their present range, and in this area Discussion they tend to be confined to high elevation Andean forests and páramos, the life zones From the standpoint of floristic diversity, with the most antipodal-like climate the South American páramos are anywhere in the neotropics. The number exceptionally rich, rivalled, perhaps, only of these disjuncts is sharply reduced in the by upper elevation cloud forests. This 132 high level of diversity can be traced to a Literature Cited number of factors. One of these, undoubtedly, is the complexity of páramo microenvironments. Available substrates Bowers, F.D. 1974. The mosses reported from Costa Rica. vary from open, dry mineral soils to The Bryologist 77: 150-171. waterlogged peats, streams and lakes, from Buck, W. & Crum, H. 1976. Revision of the genus Rozea shaded gallery forests to dry, exposed (Musci). The Bryologist 79: 406-421. boulders. Atmospheric humidity remains Crum, H. 1976. Mosses of the Great Lakes Forest. University relatively high all year long. In addition, Herbarium, University of Michigan, Ann Arbor, Michigan. the proximity downslope of the diverse Delgadillo, C. 1971. Phytogeographic studies on alpine Andean forest flora provided historically mosses of Mexico. The Bryologist 74: 331-346. an extremely rich source of potential ——————. 1979. Notes on alpine mosses of Mexico. The Bryologist páramo colonists as local orogenies 82: 629-631. elevated the mountain summits above ———————. 1982. Current knowledge on the Mexican moss flora timberline. An additional opportunity for and its temperate element. Beiheft Nova Hedwigia 71: 455-459. increasing taxonomic breadth in the ———————. 1984. Musgos alpinos de Mexico: Cofre de Perote y páramo flora occurred during the Pico de Orizaba. Biotica 9: 399-405. Pleistocene glaciation which in the Andes ——————. 1986. The Meso-American element in the moss flora saw the same 4 advances and retreats as of Mexico. Lindbergia 12: 121-124. experienced at high latitudes. Van der ——————. 1987. Musgos alpinos del Nevado de Colima, Mexico. Hammen (1974) has estimated that Bol. Soc. Bot. Mexico 47: 7-11. Andean vegetation belts moved Griffin, D. 1975. Additions to the moss flora of Venezuela. downslope by as much as 1200-1500 The Bryologist 78: 212-215. meters during the last (Wisconsin) glacial. ———————. 1977a. Mas adiciones a la flora musquena de The consequent areal expansion of the Venezuela. The Bryologist 80: 181-184. páramo life zone would have been ———————. 1977b. Un informe sobre la briologia del estado Zulia, significant, permitting floristic exchanges Venezuela. Acta Bot. Venezuelica 12: 285-292. and direct migrations between what are ———————. 1979. New records for the moss flora of Venezuela. presently isolated páramo regions. Further, The Bryologist 82: 618-619. the proximity of north-temperate and boreal ———————, Gradstein, S.R. & Aguirre, J. 1982. Studies on elements and, plausibly, of antipodal taxa Colombian cryptogams XVII. On a new antipodal element in the to the much increased páramo area would neotropical paramos - Dendrocryphaea latifolia sp. nov. (Musci). have greatly facilitated the successful Acta Bot. Neerl. 31: 175-184. establishment of species that are considered ———————, Lopez Figueiras, M. & Ruiz-Teran, L. 1973. today to represent major disjuncts. Additions to the moss flora of Venezuela from the state of Merida. Phytologia 25: 107-112. More resistant to facile explanation is the Hammen, T. van der. 1974. The Pleistocene changes of presence in the current páramo flora of vegetation and climate in tropical South America. Jour. elements with African and Australasian Biogeography 1: 3-26. affinities. Possible historical ———————— & Cleef, A. 1983. Datos para la historia de la flora reconstructions appear limited to two andina. Rev. Chilena Hist. Nat. 56: 97-107. categories, i.e., invoking continental drift ————————. 1986. Development of the high Andean paramo or visualizing long-distance transport of flora and vegetation. In Vuillemuier, F. & Monasterio, M. (eds.), viable propagules. In view of the relative High Altitude Tropical Biogeography, pp. 153-200. 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