State of knowledge of the Corallinales ( Rhodophyta ) of Tierra del Fuego and the Antarctic Peninsula *

The coralline red algae (Rhodophyta, Corallinales) are one of the abundant seaweed groups in Tierra del Fuego, Argentina and represent a principal component of the Fuegian marine ecosystems (Mendoza and Cabioch, 1986; Mendoza et al., 1996). Coralline species have a restricted vertical distribution, and some are considered as indicators of distinct ecological zones in the intertidal and subtidal. Some species exhibit a marked and restricted geoSCI. MAR., 63 (Supl. 1): 139-144 SCIENTIA MARINA 1999


INTRODUCTION
The coralline red algae (Rhodophyta, Corallinales) are one of the abundant seaweed groups in Tierra del Fuego, Argentina and represent a prin-cipal component of the Fuegian marine ecosystems (Mendoza and Cabioch, 1986;Mendoza et al., 1996).
Coralline species have a restricted vertical distribution, and some are considered as indicators of distinct ecological zones in the intertidal and subtidal.Some species exhibit a marked and restricted geo- graphic distribution related to the water temperature.Some species occur exclusively in the Subantarctic regions.
Abundance percentage of genera is expressed by the sum of the species abundance of each genus.The abundance for each species was obtained either by counting of specimens or the cover of the encrusting thallus of the same species, which was then divided by the average thallus size.In both cases 25 cm squares were used, distributed every meter all along a transect perpendicular to the coast.The transects were done on low tide days during the summer months (November to March) in 1991, 1992, 1994 and 1995 along the Atlantic coast of Tierra del Fuego (Cabo San Pablo, Cabo Viamonte, Punta María, Caleta la Misión) and monthly in 1991, 1992, 1994 and 1995 along the Beagle Channel (Puerto Brown, Islas Bridges, Bahía Golondrina, Bahía Ensenada).
The delimitation of the intertidal and subtidal ecological levels is based on the corresponding indicator species for the coast of Tierra del Fuego.Occurrence of green algae communities (Enteromorpha prolifera, Enteromorpha intestinalis and Blidingia minima var.minima) delimits the upper intertidal zone; occurrence of the first plants of red algae (Notogenia fastigiata, Sarcothalia dichotoma, Bostrichia intricata), of encrusting coralline algae (Parahydroliton falklandicum, Synarthrophyton neglectum), and of brown algae (Corycus lanceolatus, Adenocystis utricularis) corresponds to the mid intertidal zone; and occurrence of the brown algae species Lessonia nigrescens to the lower intertidal zone.Lack of Lessonia nigrescens and occurrence of thalli of encrusting coralline Pseudolithophyllum fuegianum characterize the upper limit of the subtidal, and the occurrence of forests of brown algae Macrocystis pyrifera the lower subtidal zone.

RESULTS AND CONCLUSIONS
The studies of coralline algae are not very numerous in comparison with the other algae groups.The first work on coralline algae of Tierra del Fuego was carried out by Foslie (1900;1905;1906;1907), Heydrich (1900) and Lemoine (1913;1920), specialists in this algal group.Their identifications are based on the vegetative anatomy, especially the number of pores of the conceptacles.Other authors (Ardissone, 1888;Hariot, 1895;Cotton, 1915;Skottsberg, 1923Skottsberg, , 1941) ) have reported other species.However, these studies were based on the external morphology only, and attempting to identify typical species of the boreal hemisphere in Tierra del Fuego.
In these first studies on the coralline algae of Tierra del Fuego 9 genera with 41 species were reported.Later Mendoza (1976Mendoza ( , 1988Mendoza ( , 1990)), Mendoza and Cabioch (1984, 1985, 1986, in press) and Mendoza et al. (1996) studied the geniculate and crustose coralline algae of Tierra del Fuego.These authors, on the base of the reproductive and morphological characteristics of the species, gave an insight into the biodiversity of coralline algae.Their results are highly different from those presented in the early works (Table 1).
The geniculate coralline algae are not common and are only represented in two genera: Bossiella and Corallina, and the crustose coralline genera Lithophyllum, Epilithon, Melobesia, Neogoniolithon, and Phymatolithon do not occur along the Tierra del Fuego coast.
The recent studies by Mendoza et al. (1996) and Mendoza and Cabioch (in press), on the basis of type material and the new collections in the last few years in Tierra del Fuego, report 9 genera with 17 species and 1 subspecies: I.  Mendoza and Cabioch (1986, in press) and Mendoza et al. (1996) reported that the coralline algae in Tierra del Fuego often occur in a high number of specimens of the same species and do not show a great specific diversity.Moreover, the crustose coralline are more abundant than the geniculate group.The genus Pseudolithophyllum, with only one species, is dominant and represents 35.8% of the calcareous algae (Fig. 1).Three genera are abundant: Parahydrolithon, with 4 species (P.conspectum, P. discoideum, P. falklandicum, P. subantarcticum), making up 20%; Lithothamnion, with 3 species, with 17.5%.; and Synarthrophyton, with 3 species, with 12%.The genera Clathromorphum, with 4 species, with 5.8% share, and Mesophyllum, consisting of a single species (4.9%), are frequent.Bossiella, with 1 subspecies, Corallina, with 2 species with 1.1%, and Titanoderma, consisting of 1 species (1%) are scarce (For names of species cf. last paragraph).
As to the vertical distribution, Mendoza and Cabioch (1986;in press), Mendoza et al. (1996) CORALLINALES (RHODOPHYTA) OF SOUTHERN SOUTH AMERICA 141 TABLE 1. -Former and present inventory of coralline algae in Tierra del Fuego.Species on the left were reported in prior studies, bold indicated species do not occur in Tierra del Fuego; species on the right are present identifications of those species that occur in Tierra del Fuego (Mendoza et al., 1996;Mendoza and Cabioch, in press).(Mendoza et al., 1993;1996;Mendoza and Cabioch, in press) (see Materials and Methods).
FIG. 1. -Diagrammatic representation of genera abundance of coralline algae in Tierra del Fuego, total material from various years included (see Materials and Methods) (Mendoza et al., 1993, in press;Mendoza and Cabioch, in press).
reported the coralline algae present a marked and constant vertical distribution (Fig. 2).Synarthrophy- The crustose coralline algae are characteristic of the southern hemisphere (Mendoza and Cabioch, 1986;in press;Mendoza et al., 1996), the geniculate Corallina officinalis is a cosmopolitan, and C. elongata, Bossiella orbigniana ssp.orbigniana are found in both hemispheres.
The coralline algae are better known in the Antarctic region.The first studies were made by Foslie (1906) and Lemoine (1913), specialists in this algal group.Other species were reported by Skottsberg (1923Skottsberg ( , 1941)), who was not a specialist in coralline algae.In these papers, 2 genera with 9 species were reported for this region.Lithophyllum is represented with 4 species (L.aequabile, L. discoideum, L. decipiens, L. subantarcticum), and Lithothamnion with 5 species (Lt. antarcticum, Lt. lenormandii, Lt. lichenoides, Lt. mangini, Lt. schmitzii).However, recent studies on the Corallinales of Tierra del Fuego (Mendoza et al., 1996;Mendoza and Cabioch, in press) have allowed the taxonomic identity of the species cited for the Antarctic Peninsula to be corrected, except for Lithophyllum discoideum Foslie, which due to a wrong use as a synonym of L. fueguianum (see Mendoza and Cabioch, 1984) does not permit us to state whether it is Parahydrolithon discoideum (Foslie) Mendoza and Cabioch or Pseudolithophyllum fueguianum (Heydrich) Mendoza and Cabioch (Table 2).Cinelli et al. (1989) carried out a short study of the coralline algae in the Antarctic region.In this paper, only 2 genera are given: Clathromorphum, with 2 species (Cl.obtectulum, Cl. lemoineanum), and Parahydrolithon, with 1 species (P.subantarcticum).
Consequently, since there is neither a detailed study, a review of the material already identified nor new, recently collected samples of coralline algae of the Antarctic Peninsula, it is not possible to specify at present the biodiversity of this algal group and compare it with that of Tierra del Fuego.However, we are aware of the abundance of coralline algae along the coasts of the Antarctic Peninsula, supported by the large amount of material collected in the First and Second "Expédition Antarctique Française" in 1903Française" in -1905Française" in and 1908Française" in -1910, in the Herbario PC, Paris, which has unfortunately not been studied yet.
ton neglectum and Parahydrolithon falklandicum are the dominant species in the mid intertidal, P. falklandicum is exclusive in this zone and S. neglectum lives also down into the subtidal zone.