Phylogenetic relationships and intraspecific diversity of a North Patagonian Fescue: evidence of differentiation and interspecific introgression at peripheral populations

Peripheral sites usually offer suboptimal conditions for species with wide distributions, where expression of phenotypic variability and potential interspecific hybridization might be enhanced. The Patagonian steppe, the largest and southernmost dryland ecosystem in South America, is characterized by natural rangelands dominated by grasses. Festuca pallescens is a keystone species with a wide distribution in Patagonia over diverse environments reaching the extreme arid zones in the Somuncura plateau, a biogeographical island. Our aim is to study the phylogenetic relationships among Festuca pallescens populations as well as between this species and the sympatric F. argentina in North Patagonia. We analysed fourteen populations along a west-east transect of about 500 km in North Patagonia with three types of molecular markers: ITS, chloroplast trnL-F and eight nuclear microsatellites. Bayesian inferences, maximum parsimony and maximum likelihood analyses with trnL-F and ITS showed that F. pallescens is related to the Patagonian clade within the Festuca phylogeny. However, the easternmost populations of F. pallescens at Somuncura plateau were highly differentiated from the other populations and clustered with F. argentina (a sympatric species of the Asian-American clade). Principal coordinates analyses and Bayesian clustering performed with nuclear microsatellites as well as morphoanatomical traits, showed an intermediate position of one of these easternmost populations with respect to the two species, suggesting admixture. The high genetic variability observed in these peripheral populations highlight their relevance for conservation and might be indicating the existence of evolutionary processes triggering events of speciation in the Patagonian fescues.     

Displacement of native Patagonian freshwater silverside populations (<Emphasis Type="Italic">Odontesthes hatcheri</Emphasis>, Atherinopsidae) by introgressive hybridization with introduced <Emphasis Type="Italic">O. bonariensis</Emphasis>

The Patagonian silverside Odontesthes hatcheri is a native fish restricted to streams and lakes of Patagonia (Argentina and Chile). Stocking programs to enhance recreational fisheries in man-made reservoirs have introduced a nonnative, closely-related species (the pejerrey O. bonariensis) in Patagonia almost a century ago, and yet little is known about the invasiveness of this species. To evaluate the impact of these introductions we analyze genetic data (microsatellite markers and mitochondrial DNA) to quantify the incidence of hybridization between these two species and assess potential effects on native population structure. Phylogeographic analyses reveal weak geographic differentiation among populations of O. hatcheri, in agreement with previous studies for other freshwater fishes in Patagonia strongly influenced by Quaternary glaciations and hydrographic basin changes since the last glaciation. However, many populations have unique genetic pools. In several areas, introductions resulted in extensive hybridization, with high frequencies of F2 and backcrossed hybrids in natural populations, and in some cases O. bonariensis has completely displaced the native populations. The negative impact of these introductions on native populations is correlated to temperature, a critical parameter in the face of global warming, suggesting that invasiveness of O. bonariensis may increase in the future. Our results advise against continuing stocking programs to preserve the integrity of natural populations of the Patagonian silverside.     

Isolation of <Emphasis Type="Italic">Campylobacter</Emphasis> spp. from Three Species of Antarctic Penguins in Different Geographic Locations

The presence of Campylobacter species was studied in three Antarctic penguin species, Adélie (Pygoscelis adeliae), chinstrap (Pygoscelis antarctica) and gentoo (Pygoscelis papua). A total of 390 penguins were captured in 12 different rookeries along the Antarctic Peninsula with differences in the amount of human visitation: six colonies were highly visited [Stranger Point, King George Island (P. papua and P. adeliae); Hannah Point, Livingston Island (P. papua and P. antarctica); Deception Island (P. antarctica); and Paradise Bay, Antarctic Peninsula (P. papua)], and six colonies were rarely visited [Devil’s Point, Byers Peninsula, Livingston Island (P. papua); Cierva Cove, Antarctic Peninsula (P. papua); Rongé Island (P. papua and P. antarctica); Yalour Island (P. adeliae); and Avian Island (P. adeliae)]. A total of 23 strains were isolated from penguins from nine different rookeries. Campylobacter lari subsp. lari was isolated from eight samples (seven from P. papua and one from P. adeliae); C. lari subsp. concheus from 13 (ten from P. adeliae and three from P. antarctica) and C. volucris from two samples (both from P. papua). We did not find any significant differences in the prevalence of Campylobacter spp. between the populations in highly and rarely visited areas. This is the first report of C. lari subsp. concheus and C. volucris isolation from penguins in the Antarctic region.     

Do Antarctic populations represent local or widespread phylogenetic and ecological lineages? Complicated fate of bipolar moss concepts with <Emphasis Type="Italic">Drepanocladus longifolius</Emphasis> as a case study

Bipolar moss species, extreme examples of large and disjunctive geographical ranges, belong to the most important components of the vegetation cover in Antarctica. Their appropriate taxonomic interpretations are essential for fine-scale biogeographical considerations but our knowledge on their phylogenetic affinities still remains limited. Here, we address the history of the Antarctic populations of Drepanocladus longifolius, a moss species widely considered a bipolar taxon. First, based on a worldwide sampling, we verify its assumed bipolar status. Then, we ask whether its current Antarctic populations have persisted throughout at least the last major glaciation in situ or, alternatively, are they a recent, postglacial element. Phylogenetic analyses together with investigation of morphological characters were used to infer relationships among accessions representing the whole distribution range of the taxon. Morphological and phylogenetic data strictly segregated specimens from the Southern and the Northern Hemisphere, with an exception of Australian populations that were included in the latter group. The Antarctic, sub-Antarctic and South American populations belong to a single clade and are treated as D. longifolius s. str., which consequently is not a bipolar taxon. All Northern Hemisphere populations and the ones from Australia represent D. capillifolius, a lately neglected taxon, which thus displays a true bipolar distribution pattern but not comprising the Antarctic and South American populations. These results provide a sound example of key importance of a detailed taxonomical and phylogenetic treatment as a basis for biogeographical studies. In D. longifolius s. str., a homogeneity in all non-coding nuclear and plastid regions was observed throughout the whole range. It contrasted with the presence of one missense mutation in the rps4 gene in all examined Antarctic populations, which correlated with their distinct ecological situation. While identity of non-coding sequences in D. longifolius populations indicates a postglacial recruitment of extant Antarctic populations from extra-regional locations rather than a long-term in situ survival, the mutation in the rps4 gene may be hypothesised to reflect an adaptive response of plants to the Antarctic environment.     

The taxonomic challenge posed by the Antarctic echinoids <Emphasis Type="Italic">Abatus bidens</Emphasis> and <Emphasis Type="Italic">Abatus cavernosus</Emphasis> (Schizasteridae,Echinoidea)

Cryptic species have been repeatedly described for two decades among the Antarctic fauna, challenging the classic model of Antarctic species with circumpolar distributions and leading to revisit the richness of the Antarctic fauna. No cryptic species had been so far recorded among Antarctic echinoids, which are, however, relatively well diversified in the Southern Ocean. The R/V Polarstern cruise PS81 (ANT XXIX/3) came across populations of Abatus bidens, a schizasterid so far known by few specimens that were found living in sympatry with the species Abatus cavernosus. The species A. cavernosus is reported to have a circum-Antarctic distribution, while A. bidens is only recorded with certainty in South Georgia and at the northern tip of the Antarctic Peninsula. Based on genetic and morphological analyses, our results clearly show that A. bidens and A. cavernosus are two distinct species. The analyzed specimens of A. bidens group together in two haplogroups separated from one another by 2.7 % of nucleotide differences. They are located in the Weddell Sea and in the Bransfield Strait. Specimens of A. cavernosus form one single haplogroup separated from haplogroups of A. bidens by 5 and 3.5 % of nucleotide differences, respectively. The species was collected in the Drake Passage and in the Bransfield Strait. Morphological analyses differentiate A. bidens from A. cavernosus. In contrast, the two genetic groups of A. bidens cannot be differentiated from one another based on morphology alone, suggesting that they may represent a case of cryptic species, common in many Antarctic taxa, but not yet reported in Antarctic echinoids. This needs to be confirmed by complementary analyses of independent genetic markers.     

Soluble carbohydrates in developing and mature diaspores of polar Caryophyllaceae and Poaceae

The accumulation of soluble carbohydrates in maturing diaspores of flowering plants comprising Arctic populations of Cerastium alpinum, indigenous Antarctic species Colobanthus quitensis and Deschampsia antarctica, and cosmopolitan Poa annua from the Antarctic was investigated. For comparative purposes, the diaspores of two species of flowering plants growing in the area of Olsztyn (Poland), Poa annua (Poaceae) and Cerastium arvense (Caryophyllaceae) were used. A qualitative and quantitative analysis of soluble carbohydrates conducted by means of high-resolution gas chromatography showed that monosaccharides (glucose and fructose), maltose and sucrose, raffinose, myo-inositol and galactinol are ubiquitous in developing and mature diaspores among investigated species. Moreover, D. antarctica and P. annua caryopses additionally contained stachyose and 1-kestose; the seeds of Caryophyllaceae studied were found to contain d-pinitol and d-ononitol. The development and maturation of the seeds of polar Caryophyllaceae and Poaceae were accompanied by the changes in the concentration of their soluble carbohydrates. During maturation, seeds accumulated galactinol and raffinose family of oligosaccharides (RFOs), except C. quitensis. Although seeds of the studied Caryophyllaceae contained d-pinitol and lower amounts of d-ononitol, they did not accumulate α-d-galactoside derivatives of mentioned cyclitols. P. annua caryopses, occurring in the Antarctic, were found to accumulate considerably higher amounts of sucrose and 1-kestose than those developed in Olsztyn.     

The diet of the Antarctic fur seal <Emphasis Type="Italic">Arctocephalus gazella</Emphasis> at the South Orkney Islands in ten consecutive years

To improve the knowledge on the Antarctic fur seal foraging behavior, evaluate whether changes in its diet are associated with changes in prey availability, and evaluate whether fisheries had negative impacts on Antarctic fur seal populations, a total of 1359 scats of non-breeding males were collected in ten consecutive sampling periods between 1994 and 2003 at Laurie Island, South Orkney Islands. Antarctic krill was the most numerous prey throughout the sampling period followed in importance by fish prey. Antarctic krill also predominated by reconstructed mass, except during 1994 and 1998 when penguins were the most important prey, and during 1995 when fish dominated. Among fish, demersal-benthic species (mainly Gobionotothen gibberifrons, Chaenocephalus aceratus and Chionodraco rastrospinosus) dominated the diet except in 1997, 1998, 1999 and 2002 when myctophids (mainly Gymnoscopelus nicholsi and Electrona antarctica) were the most important fish prey. In seasons when fish dominated the diet, the diet was primarily comprised of demersal species. Although our results are in overall agreement with previous studies, the contribution to the diet of the main preys changed throughout the sampling period, probably in parallel with changes in prey abundance. According to historical results on fish consumption, the fisheries carried out in the past have had negative impacts on seal populations from the South Orkney Islands.     

Molecular evidence in <Emphasis Type="Italic">Diplotaxis</Emphasis> (Brassicaceae) suggests a Quaternary origin of the Cape Verdean flora

In comparison with other Macaronesian Islands (e.g., the Canary Islands), the Cape Verde Islands have received little attention in terms of plant molecular phylogenetic studies, which might also elucidate the general floristic history of this archipelago. The Cape Verdean vascular plant flora (ca. 12% endemics) has traditionally been regarded as relict of a former subtropical Tertiary flora. In contrast, it has been postulated more recently that the flora is much younger and of Pleistocene origin. To test these hypotheses, we have produced molecular phylogenies associated with a molecular clock approach, sampling all nine Cape Verdean endemic Diplotaxis taxa and 21 accessions representing the D. harra complex from across its distributional range. Analyzing three molecular markers from the nuclear and chloroplast genome, we provide evidence that the Cape Verdean endemic Diplotaxis originated from North African D. harra populations in Pleistocene times, putatively linked to the genesis of the (western) Sahara. This adds to the emerging picture that the present Cape Verdean flora is of Pleistocene origin.     

Three new species of Ophiostomatales from <Emphasis Type="Italic">Nothofagus</Emphasis> in Patagonia

The Ophiostomatales (Ascomycota) include mainly insect and mite-associated fungi, the majority of which are found on trees. Very little is known regarding the occurrence or diversity of these fungi in South America. The aim of this study was to consider their occurrence on native Nothofagus trees in the Patagonian Andes of Argentina. Isolates were collected in national parks and provincial reserves in Patagonia between 2009 and 2011. These were grouped based on morphology, and 22 representative isolates were included in phylogenetic analyses based on sequence data of multiple loci (LSU, ITS, beta-tubulin and translation elongation factor-1 alpha genes). The isolates could be assigned to ten different taxa, and included eight species of Ophiostoma s. l., one species of Leptographium, and one species in the Sporothrix lignivora complex. Three of the species are described as new, including Ophiostoma patagonicum, Leptographium gestamen, and Sporothrix cabralii. Ophiostoma quercus and O. noveae-zelandiae are reported for the first time from Argentina, and we show that the latter species is distinct from O. pluriannulatum, in contrast to a previous suggestion that they represent the same taxon.     

Geographic patterns of genetic variation in nuclear and chloroplast genomes of two related oaks (<Emphasis Type="Italic">Quercus aliena</Emphasis> and <Emphasis Type="Italic">Q. serrata</Emphasis>) in Japan: implications for seed and seedling transfer

In this study, we assessed geographic patterns of genetic variations in nuclear and chloroplast genomes of two related native oaks in Japan, Quercus aliena and Q. serrata, in order to facilitate development of genetic guidelines for transfer of planting stocks for each species. A total of 12 populations of Q. aliena and 44 populations of Q. serrata were analyzed in this study. Genotyping of nuclear microsatellites in Q. aliena was done with only nine populations (n = 212) due to limited numbers of individuals in two populations, while all 12 populations (n = 89) were used in sequencing chloroplast DNA (cpDNA). In Q. serrata, 43 populations (n = 1032) were genotyped by nuclear microsatellite markers, while cpDNA of 44 populations (n = 350) was sequenced. As anticipated, geographic patterns detected in the variations of Q. aliena’s nuclear genome and its chloroplast haplotype distribution clearly distinguished northern and southern groups of populations. However, those of Q. serrata were inconsistent. The geographic distribution of its chloroplast haplotypes tends to show the predicted differentiation between northern and southern lineages, but geographic signals in the genetic structure of its nuclear microsatellites are weak. Therefore, treating northern and southern regions of Japan as genetically distinct transferrable zones for planting stocks is highly warranted for Q. aliena. For Q. serrata, the strong NE-SW geographic structure of cpDNA should be considered.     

Adaptation of the seed reproduction system to conditions of Maritime Antarctic in <Emphasis Type="Italic">Deschampsia antarctica</Emphasis> E. Desv.

Deschampsia antarctica3 E. Desv. is one of the two flowering plants that, along with Colobanthus quitensis (Kunth) Bartl., was able to settle the ice-free areas of Antarctica. In order to identify the possible adaptations of the D. antarctica reproductive system to adverse environmental conditions, comparative cytoembryological analysis of plants of this species growing on the Antarctic Peninsula with plants of the closely related species D. beringensis Hult. from the Kamchatka Peninsula was conducted. It was found that both species are characterized by sexual mode of reproduction, equal size of pollen grains (25.5 ± 2.2 and 26.2 ± 1.9 μm, respectively), same features of the embryo sac structure, and emryo- and endospermogenesis. Interspecies differences have been found in mature embryo sac size (326.8 ± 12.8 and 161.7 ± 10.4 μm), pollen sterility percentage (86.1 ± 8.9 and 35.3 ± 9.2%), and quantity of pollen in the anthers (140 ± 15.3 and 1578 ± 88.6). Possible causes and significance of these differences are discussed. No unique adaptations of seed reproduction system that are inherent exclusively to D. antarctica were found. The D. antarctica reproduction strategy is based on the combination of autogamy (and its extreme form cleistogamy) with production of excess pollen quantity for its mode of pollination.     

<Emphasis Type="Italic">Usnea antarctica</Emphasis>, an important Antarctic lichen,is vulnerable to aspects of regional environmental change

Studies of cryptogam responses to climate change in the polar regions are scarce because these slow-growing organisms require long-term monitoring studies. Here, we analyse the response of a lichen and moss community to 10 years of passive environmental manipulation using open-top chambers (OTCs) in the maritime Antarctic region. Cover of the dominant lichen Usnea antarctica declined by 71 % in the OTCs. However, less dominant lichen species showed no significant responses except for an increase in Ochrolechia frigida, which typically covered dying lichen and moss vegetation. There were no detectable responses in the moss or associated micro-arthropod communities to the influence of the OTCs. Based on calculated respiration rates, we hypothesise that the decline of U. antarctica was most likely caused by increased net winter respiration rates (11 %), driven by the higher temperatures and lower light levels experienced inside the OTCs as a result of greater snow accumulation. During summer, U. antarctica appears unable to compensate for this increased carbon loss, leading to a negative carbon balance on an annual basis, and the lichen therefore appears to be vulnerable to such climate change simulations. These findings indicate that U. antarctica dominated fell-fields may change dramatically if current environmental change trends continue in the maritime Antarctic, especially if associated with increases in winter snow depth or duration.     

Species tree phylogeny,character evolution,and biogeography of the Patagonian genus <Emphasis Type="Italic">Anarthrophyllum</Emphasis> Benth. (Fabaceae)

Geologic events promoting the aridization of southern South America contributed to lineage divergences and species differentiation through geographic (allopatric divergence) and biotic and abiotic factors (ecological divergence). For the genus Anarthrophyllum, which is distributed in arid and semi-arid regions of Patagonia, we assessed how these factors affected species diversification and reconstructed its possible biogeographic history in South American arid environments. Sequences were obtained from two molecular markers: the ITS nuclear region and the trnS-trnG plastid region. Using Parsimony, Maximum likelihood and Bayesian inference individual gene trees were reconstructed, and a species tree was obtained using multi-species coalescent analysis. Divergence times among species were estimated using secondary calibrations. Flexible Bayesian models and stochastic character mapping were used to elucidate ancestral geographic distributions and the evolution of the floral and vegetative phenotypes in the genus. Gene trees and species tree analyses strongly support Anarthrophyllum as monophyletic; all analyses consistently retrieved three well-supported main clades: High Andean Clade, Patagonian Clade 1, and Patagonian Clade 2. Main diversification events occurred concomitant with the Andean uplift and steppe aridization; the Andean mountain range possibly acted as a species barrier for the High Andean Clade. Vegetative traits showed adaptations to harsh climates in some clades, while pollinator-related floral features were associated with independent diversification in bee- and bird-pollinated clades within both Patagonian Clades. In conclusion, evolutionary and biogeographic history of Anarthrophyllum resulted from the action of ecological, historical, and geographic factors that acted either alternatively or simultaneously.     

Thermotolerance and molecular chaperone function of an SGT1-like protein from the psychrophilic yeast, <Emphasis Type="Italic">Glaciozyma antarctica</Emphasis>

The ability of eukaryotes to adapt to an extreme range of temperatures is critically important for survival. Although adaptation to extreme high temperatures is well understood, reflecting the action of molecular chaperones, it is unclear whether these molecules play a role in survival at extremely low temperatures. The recent genome sequencing of the yeast Glaciozyma antarctica, isolated from Antarctic sea ice near Casey Station, provides an opportunity to investigate the role of molecular chaperones in adaptation to cold temperatures. We isolated a G. antarctica homologue of small heat shock protein 20 (HSP20), GaSGT1, and observed that the GaSGT1 mRNA expression in G. antarctica was markedly increased following culture exposure at low temperatures. Additionally, we demonstrated that GaSGT1 overexpression in Escherichia coli protected these bacteria from exposure to both high and low temperatures, which are lethal for growth. The recombinant GaSGT1 retained up to 60 % of its native luciferase activity after exposure to luciferase-denaturing temperatures. These results suggest that GaSGT1 promotes cell thermotolerance and employs molecular chaperone-like activity toward temperature assaults.     

Modern State of Populations of Endemic <Emphasis Type="Italic">Oxytropis</Emphasis> Species from Baikal Siberia and Their Phylogenetic Relationships Based on Chloroplast DNA Markers

The genetic diversity and population structure of the endemic species of Baikal Siberia Oxytropis triphylla, O. bargusinensis, and O. interposita were studied for the first time on the basis of the nucleotide polymorphism of intergenic spacers psbA–trnH, trnL–trnF, and trnS–trnG of chloroplast DNA. All populations of these species were characterized by a high haplotype (0.762–0.924) and relatively low nucleotide (0.0011–0.0022) diversity. Analysis of the distribution of variability in O. triphylla and O. bargusinensis showed that there was no significant genetic differentiation between populations of each species; the gene flow was 4.43 and 8.91, respectively. The high level of genetic diversity in the studied populations indicates a relatively stable state of these populations. A study of the phylogenetic relationships of closely related species confirms the concept of the origin of O. bargusinensis and O. tompudae as a result of intersectional hybridization of the species of the sections Orobia and Verticillares.     

A multivariate morphometric delimitation of species boundaries in the South American genus <Emphasis Type="Italic">Nicoraepoa</Emphasis> (Poaceae: Pooideae: Poeae)

A multivariate morphometric study of the genus Nicoraepoa was carried out to examine patterns of morphological variation among the species and to identify additional characters to allow a clearer delimitation among species. Nicoraepoa is a taxonomically complex genus comprising seven species endemic to South America. Although most of the species are well delimited, two of them, N. andina and N. chonotica, are morphologically similar and very difficult to separate. The morphological variation among species, with overlapping morphological characters, pseudovivipary and possible hybridization make species boundaries unclear. In the present paper, sixty-seven characters were scored for a total of 216 specimens and analyzed using ordination, cluster and discriminant analyses. Based on multivariate results, we recognized species groups and morphological diagnostic characters that allow clearer species delimitation. As a result, N. chonotica has been transferred to N. andina as a subspecies that inhabit southern Patagonia. Other taxa could be recognized and delimited by diagnostic characters: N. erinacea, N. pugionifolia, N. stepparia, N. subenervis subsp. spegazziniana and N. subenervis subsp. subenervis. Moreover, we discuss the possibility that a new species from Bolivia, based on only one specimen, closely related to N. subenervis should be ascribed in Nicoraepoa.     

Distributional and ecophysiological study on the Antarctic lichens species pair <Emphasis Type="Italic">Usnea antarctica</Emphasis>/<Emphasis Type="Italic">Usnea aurantiaco</Emphasis>-<Emphasis Type="Italic">atra</Emphasis>

The factors that control lichen distribution in Antarctica are still not well understood, and in this investigation we focused on the distribution, local and continental, and gas exchange of a species pair, closely related lichens with differing reproductive strategies, Usnea aurantiaco-atra (fertile) and Usnea antarctica (sterile, sorediate). The local distributions of these species were recorded along an altitudinal gradient of nearly 300 m at South Bay, Livingston Island, and microclimate was also recorded over 1 year. The photosynthetic responses to temperature, light and thallus water content were determined under controlled conditions in the laboratory. The species were almost identical in their photosynthetic profiles. Locally, on Livingston Island, U. antarctica was confined to low altitude sites which were warmer and drier, whilst U. aurantiaco-atra was present at all altitudes. This contrasts with its distribution across Antarctica where U. antarctica grows 9° latitude further south than U. aurantiaco-atra. Temperature appears not to be the main controller of distribution in these species, but dryness of habitat, which will influence length of activity periods, may be important.     

New Middle Miocene Caviomorph Rodents from Quebrada Honda,Bolivia

The rodents of the middle Miocene fauna of Quebrada Honda Bolivia are described. The most abundant rodent is the chinchillid Prolagostomus sp. More precise identification of this species will require revision of early to middle Miocene lagostomines, taking into account variation in modern populations. The next most common rodents are the tiny octodontoid Acarechimys, sp. nov.?, and the caviid Guiomys unica. The Acarechimys species may be unique to Quebrada Honda, but verification awaits revision of this geographically and temporally widespread genus. Guiomys unica is a recently described species otherwise known only from two Patagonian localities, El Petiso and Río Chico. Two rodents are unique to Quebrada Honda. Mesoprocta hypsodus, gen. et sp. nov., is a dasyproctid distinguished by its very hypsodont, cement-covered cheek teeth. Quebradahondomys potosiensis, gen. et sp. nov., is an adelphomyine echimyid distinguished by the less oblique lophids of its trilophodont cheek teeth, among other features. The rodents of Quebrada Honda are more similar to those of Patagonia than those of northern South America, paralleling patterns seen in other mammal groups from this fauna.     

Extraordinary abundance of hydrocorals (Cnidaria,Hydrozoa, Stylasteridae) in shallow water of the Patagonian fjord region

During two scuba-diving expeditions in 2005 and 2006, stylasterids were documented and sampled from fjords and channels in the Central Patagonian Zone, Chile. At 15 of a total of 33 sampling sites we found colonies of Errina antarctica. We discuss the observed distribution patterns and the variability of colony shapes. In some regions we found E. antarctica to occur in extraordinary high densities on primary and secondary hard substratum below 10 m. In the archipelago Madre de Dios we discovered large colonies of E. antarctica covering areas of more than 10,000 m² with coverage exceeding 80%. The dense accumulations of E. antarctica have reef-like structure and form complex habitats. At one site we observed extensive mechanical damage to the corals that may result from coral extraction by divers and/or from boat anchors. Slow growth, fragility, scarceness and the lack of knowledge on their ecology make these spectacular and unique biocenoses very susceptible for damages and require protection and further studies.