Rocky Fields Research Articles

Habranthus (Amaryllidaceae) do Brasil

Habranthus é um gênero com forte apelo ornamental e apresenta de 30 a 40 espécies distribuídas desde o sudeste dos Estados Unidos, México até a América do Sul. Sua delimitação, bem como das espécies, é confusa e a taxonomia é complicada, com vários casos de tipificação necessitando serem esclarecidos. Os objetivos deste estudo foram realizar o levantamento das espécies brasileiras de Habranthus do Brasil e apresentação de descrições, ilustrações, chave de identificação e comentários para todas as espécies. Foram identificadas 21 espécies cujas distribuições abrangem os domínios fitogeográficos da Caatinga, Cerrado, Mata Atlântica e Pantanal, ocorrendo em vegetação de caatinga arbustivo-arbórea, campo rupestre, carrasco, mata de galeria, campo limpo, cerrado sensu stricto, cerrado de altitude e em locais alagáveis.

Anatomia comparada dos órgãos vegetativos de espécies de Bulbophyllum seção Didactyle (Lindl.) Cogn. e Bulbophyllum seção Xiphizusa Rchb.f. (Orchidaceae)

Bulbophyllum sect. Didactyle e B.sect. Xiphizusa são grupos monofiléticos irmãos, inseridos no clado neotropical do gênero. As espécies ocorrem como epífitas ou rupícolas em áreas montanhosas com predomínio dos campos rupestres. O objetivo foi descrever comparativamente a anatomia dos órgãos vegetativos de 13 espécies dessas seções. O trabalho evidencia pela primeira vez a secreção lipofílica dos tricomas na folha jovem; caracteres xeromorfos uniformes entre as duas seções, como a cutícula espessa, presença de idioblastos, parênquima aquífero e fibras junto aos feixes vasculares; a ausência de cristais prismáticos na raiz e bulbo nas espécies de B.sect. Didactyle e a ausência de idioblastos com espessamento espiralados na raiz, espessamento na parede epidérmica do pseudobulbo e predomínio de mesofilo heterogêneo nas folhas das espécies de B. sect. Xiphizusa podem ser considerados estados de caractere sinapomórficos para as seções mostrando a importância da anatomia em estudos sistemáticos.

Interactions between substrate temperature and humidity in signalling cyclical dormancy in seeds of two perennial tropical species

AbstractThe involvement of environmental factors in dormancy cycling is well known in temperate annual species, but it is not known how interaction between soil temperatures and humidity can modulate dormancy in perennial tropical species. In this study the effects were evaluated of substrate temperature and humidity on the modulation of the acquisition and overcoming of secondary dormancy in the buried seeds of two endemic Eriocaulaceae species from the rocky fields (campos rupestres) vegetation in south-eastern Brazil. Fresh seeds ofComanthera bisulcataandSyngonanthus verticillatuswere buried and subsequently maintained at temperatures of 15, 20, 25 and 30°C, under three substrate humidity levels (boggy, humid and humid/dry). The seeds were exhumed every 3 months and tested for germination (20°C, 12 h photoperiod) and viability (tetrazolium test). The seeds of both species acquired dormancy after burial in all of the treatments. During the experimental period they demonstrated cycles of acquisition and overcoming of dormancy that were most evident in the treatments involving alterations of the substrate humidity (humid/dry regime) that coincided with the environmental conditions found naturally in the region of origin of the species. The seeds gradually lost dormancy during the dry period and re-acquired it when exposed again to humidity; dormancy would once again be overcome during the subsequent dry period. Burial promoted the acquisition of dormancy inC. bisulcataandS. verticillatusseeds; the lowest temperature tested favoured overcoming dormancy; and varying the humidity regime signalled the acquisition and the overcoming of secondary dormancy.

Diversity and distribution of oligochaetes in tropical forested streams, southeastern Brazil

The distribution and beta diversity of oligochaete assemblages were investigated in different spatial scales to verify the influence of environmental factors and geographic distance on their structure. Two types of mesohabitats (riffles and pools) were sampled in eight first-order streams located in four preservation areas (Poco D’Anta Municipal Biological Reserve, Santa Cândida Municipal Biological Reserve, Ibitipoca State Park and a private farm called Fazenda Floresta) and two Atlantic Forest phytophysiognomies (Seasonal Semideciduous Forest and Rocky Field). Variations in the taxon richness, abundance and composition of the oligochaete assemblages occurred between streams and phytophysiognomies, but not between riffles and pools in the same stream. Low beta diversity values were found and both turnover and nestedness contributed similarly in the environments studied, which could have occurred because of the high capability of oligochaetes to adapt to different environmental conditions. Although the canonical correspondence analysis explained 85.5% of the data (first three axes), the partial Mantel test showed greater influence of geographic distance on the faunal composition than the environmental variables measured. Simple linear regression confirmed this result and showed that the decay of similarity increased with distance between streams. The information from this study sheds light on how environmental and spatial factors determine the variation in the distribution and diversity of oligochaetes in forested low-order streams.

Trichomes related to an unusual method of water retention and protection of the stem apex in an arid zone perennial species.

It is well known that trichomes protect plant organs, and several studies have investigated their role in the adaptation of plants to harsh environments. Recent studies have shown that the production of hydrophilic substances by glandular trichomes and the deposition of this secretion on young organs may facilitate water retention, thus preventing desiccation and favouring organ growth until the plant develops other protective mechanisms. Lychnophora diamantinana is a species endemic to the Brazilian 'campos rupestres' (rocky fields), a region characterized by intense solar radiation and water deficits. This study sought to investigate trichomes and the origin of the substances observed on the stem apices of L. diamantinana. Samples of stem apices, young and expanded leaves were studied using standard techniques, including light microscopy and scanning and transmission electron microscopy. Histochemical tests were used to identify the major groups of metabolites present in the trichomes and the hyaline material deposited on the apices. Non-glandular trichomes and glandular trichomes were observed. The material deposited on the stem apices was hyaline, highly hydrophilic and viscous. This hyaline material primarily consists of carbohydrates that result from the partial degradation of the cell wall of uniseriate trichomes. This degradation occurs at the same time that glandular trichomes secrete terpenoids, phenolic compounds and proteins. These results suggest that the non-glandular trichomes on the leaves of L. diamantinana help protect the young organ, particularly against desiccation, by deposition of highly hydrated substances on the apices. Furthermore, the secretion of glandular trichomes probably repels herbivore and pathogen attacks.

Inulin contents and tissue distribution in underground storage organs of Asteraceae species from the Brazilian rocky fields

Geophytes are widespread in rocky fields, having evolved to survive adverse environmental conditions mainly because of their underground storage organs and reserve compounds. Among these compounds, carbohydrates have several functions other than as an energy source, including protection against drought and extreme temperatures. In this work, we analyzed the composition and tissue distribution of carbohydrates in the underground organs of four Asteraceae species from a preserved area of rocky fields in the Brazilian Cerrado. Soluble carbohydrates were quantified and analyzed by HPAEC–PAD, and starch was analyzed by an enzymatic assay. All species (Baccharis subdentata DC., Chresta curumbensis (Philipson) H.Rob., Lessingianthus floccosus (Gardner) H.Rob., and Strophopappus glomeratus (Gardner) R.Esteves) store long-chain inulin-type fructans. Among them, C. curumbensis presented the highest amount of soluble carbohydrates, comprising 25% of the reserve organ dry mass. Inulin sphero-crystals were visualized under polarized light, mainly in the vascular cylinder. Buds were found on the underground organs of B. subdentata and C. curumbensis, and secretory structures were identified in S. glomeratus, L. floccosus, and C. curumbensis. The occurrence of buds, secretory structures, and fructans in these organs is probably related to ecophysiological strategies used as defense and survival mechanisms in response to stress conditions, particularly drought and fire, that occur frequently in rocky fields.

An illustrated checklist of Bromeliaceae from Parque Estadual do Rio Preto, Minas Gerais, Brazil, with notes on phytogeography and one new species of Cryptanthus

A checklist of the 14 genera and 34 species of Bromeliaceae from the Parque Estadual do Rio Preto in Sao Goncalo do Rio Preto municipality, Minas Gerais state, southeastern Brazil, is presented. The Tillandsioideae was the most diverse subfamily and was found to be concentrated in rocky field areas. Bromelioideae is also a species rich subfamily, but its taxa have shown a preference to forested areas and savannas at lower altitudes. Pitcairnioideae is highlighted by its level of endemism, but has only four species. Cryptanthus micrus, a new species found in this area is described and illustrated. Our cluster analysis indicated that the Rio Preto State Park has a Bromeliaceae flora more similar to that from Pico do Itambe and Grao Mogol State Parks. Taxa like Dyckia glandulosa, Orthophytum itambense and Vriesea medusa, which were previously considered to be endemic to Pico do Itambe, now have their area of occurrence extended to Rio Preto. These new occurrences highlight the importance to create a corridor joining these neighboring reserves to connect populations of narrowly ranged or rare species. In this work we present pictures of 19 species in their habitats within the park, and we hope that these illustrations will help in the identification and conservation of these taxa.

Competitive Interactions in Ant Assemblage in a Rocky Field Environment: Is Being Fast and Attacking the Best Strategy?

The ant assemblage structure can be molded by mechanisms such as competition and dominance-discovery trade-off. In harsh circumstances is likely that ant species who control the food resource are the first to arrive at the baits, are more aggressive (behavioral dominance), abundant (numerical dominance) and, thus, ecologically dominants. By this characteristics combination, the dominance-discovery should not be a trade-off, but a positive relationship. Here, we examined the interactions among nine ant species in a rocky field area, in the Ibitipoca State Park, Minas Gerais, Brazil. By offering baits, we observe the dominance-discovery ability and the behaviors of attack, avoidance and coexistence of each species. We showed that Crematogaster sericea , Pheidole obscurithorax and Pheidole radoszkowskii were the best discoverers of the food resource and dominated it numerically, being this way considered ecologically dominants. Despite P. radoszkowskii being part of this relationship, this interpretation should be taken cautiously. Its dominance at the baits was assured by their high discovery ability and abundance, but the behavioral strategy exhibited was avoidance, not aggressiveness as C. sericea and P. obscurithorax . Thus, we can suppose that the discovery-dominance trade-off was broken by the linked characteristics that define the ecological dominant status of these species. Also, P. radoszkowskii demonstrates that others strategies could surpass the set of being fast and attack, and thus this is not the best strategy for all. In harsh circumstances each species has its own best strategy.

A new paludicolous species of Malaxis (Orchidaceae) from Argentina and Uruguay

Malaxis irmae, a new orchid species from the Paraná and Uruguay river basins in northeast Argentina and Uruguay, is described and illustrated. It is similar in size and overall floral morphology to Malaxis cipoensis, a species endemic to upland rocky fields on the Espinhaço range in Southeastern Brazil, which is its closest relative according to a cladistics analysis of nuclear (ITS) and plastid (matK) DNA sequences presented here. However, M. irmae is distinguished from M. cipoensis by inhabiting lowland marshy grasslands, possessing 3−5 long-petiolate leaves per shoot (vs. 2 shortly petiolate leaves), cylindrical raceme (vs. corymbose), pale green flowers (vs. green-orange flowers) and less prominent basal labellum lobules. Malaxis irmae is morphologically also similar to the Brazilian M. warmingii, which differs in its much larger plants and prominent basal labellum lobes.

Dasyphyllum diamantinense (Asteraceae, Barnadesioideae): a new species from the Chapada Diamantina, Bahia State, Brazil

Dasyphyllum diamantinense is a new species endemic to the Chapada Diamantina Mountains in the northern section of the Espinhaço Range, in Bahia State, Brazil, which grows in rocky fields, forests and savannas, and on inselbergs. The new taxon is morphologically similar to Dasyphyllum leptacanthum. Affinities and diagnostic characters are discussed, and illustrations and a map are provided.

A new species of the genus Chamaecrista (Leguminosae, Caesalpinioideae) from Chapada dos Veadeiros, Goiás, Brazil

Chamaecrista frondosa from Brazil is described, illustrated, and discussed herein. This species is morphologically similar to C. psoraleopsis in its general leaflet shape and belongs to Chamaecrista sect. Absus series Microphyllae due to its caespitose, subshrubby habit, young branches, inflorescence axis, and pedicel with glandular trichomes, leaflets resin-dotted, ascending in the rachis and partly facing each other, as well as flowers with 10 fertile stamens. The species appears to be restricted to Cerrado sensu stricto and rocky fields in the Chapada dos Veadeiros National Park, an area with notable endemism. A key to the species of Chamaecrista sect. Absus series Microphyllae occurring in the region is provided.

A New and Threatened Species of Passiflora Section <I>Decaloba</I> (Passifloraceae) from Minas Gerais State, Brazil

Abstract A new species of Passiflora from the rocky fields (“campos rupestres”) of Minas Gerais State is described: P. rupestris, which belongs to Passiflrora sect. Decaloba. The species is distinguished by having a 3-lobed obtriangular leaf blade that is longer than wide, of small size (1.5–2.9 × 1.3–2.2 cm), without ocelli, and with slightly divergent lobes (27–40°), and a particular combination of characteristics of the flower and fruit. The species is illustrated and its affinities with other species are discussed. Passiflora rupestris must be regarded as critically endangered because of its extremely limited occurrence.

Asteraceae Dumort nos campos rupestres do Parque Estadual do Itacolomi, Minas Gerais, Brasil: Barnadesieae e Mutisieae

O estudo das tribos Barnadesieae e Mutisieae é parte do levantamento florístico das espécies de Asteraceae nos campos rupestres do Parque Estadual do Itacolomi (PEI) em Minas Gerais, realizado através de coletas mensais no período de agosto de 2005 a agosto de 2007. Para as duas tribos foram identificadas 21 espécies pertencentes a seis gêneros: Dasyphyllum Kunth com quatro espécies e uma variedade; Chaptalia Vent.(quatro spp.), Gochnatia Kunth. (três spp.), Mutisia L.f. (uma spp.), Richterago Kuntze (seis spp.) e Trixis P. Br. (três spp.). Destas espécies, a maioria é restrita aos Campos Rupestres da Cadeia do Espinhaço ou áreas próximas com vegetação de transição, sendo quatro endêmicas de Minas Gerais. São apresentadas chaves de gêneros e espécies, descrições morfológicas, comentários taxonômicos, informações sobre a distribuição geográfica das espécies e ilustrações.

Geographic distribution patterns of Leguminosae and their relevance for the conservation of the Itacolomi State Park, Minas Gerais, Brazil

This study identified patterns of geographic distribution of 102 Leguminosae taxa within the Park, based on literature data and herbarium specimens. Among the taxa, 38 grow exclusively in CamposRupestres (rocky fields) and 49 in the Semideciduous Forest. Eleven patterns of geographic distribution were identified, of which the West-East-Central South America pattern was the most representative, with 27 taxa. Of the 102 sampled taxa of Leguminosae, five are endemic to the Espinhaço Range and ten are included in lists of endangered species of the flora of Brazil and Minas Gerais. Information on these taxa is crucial to provide conservation practices for conserving the vegetation formations of the PEIT.

Microsatellite loci for Orthophytum ophiuroides (Bromelioideae, Bromeliaceae) species adapted to neotropical rock outcrops.

• Premise of the study: Microsatellite primers were developed for Orthophytum ophiuroides, a rupicolous bromeliad species endemic to neotropical rocky fields. These microsatellite loci will be used to investigate population differentiation and species cohesion in such fragmented environments. The loci were tested for cross-amplification in related bromeliad species.• Methods and Results: Eleven polymorphic microsatellite markers were isolated and characterized from an enriched library of O. ophiuroides. The loci were tested on 42 individuals from two populations of this species. The number of alleles per locus ranged from three to nine and the expected and observed heterozygosities ranged from 0.167 to 0.870 and from 0.369 to 0.958, respectively. Seven loci successfully amplified in other related bromeliad species.• Conclusions: Our results suggest that the microsatellite loci developed here will be useful to assess genetic diversity and gene flow in O. ophiuroides for the investigation of population differentiation and species cohesion in neotropical mountainous habitats.

New bioacoustic and distributional data on Bokermannohyla sapiranga Brandão et al., 2012 (Anura: Hylidae): revisiting its diagnosis in comparison withB. pseudopseudis (Miranda-Ribeiro, 1937).

In this paper, we provide new bioacoustic and distributional data on Bokermannohyla sapiranga, as well as additional comparative bioacoustic data on topotypes of B. pseudopseudis, and re-evaluate the differential diagnosis of the former species with respect to the latter. Head shapes (dorsal and lateral views) presented such variation that should not be used to differentially diagnose them as originally proposed. On the other hand, the presence of a dermal ridge along outer tarsi, and color patterns of the eyes and dorsal surface of hand/toe disks still represent diagnostic characters between both species. We also found differences in temporal (call duration; notes per call), spectral (dominant frequency; harmonics), and structural (pulsed/non-pulsed note structure) traits of their calls. Distribution of B. sapiranga is extended eastward (Paracatu), which corresponds to the first record for the State of Minas Gerais, whereas B. pseudopseudis distribution seems to be restricted to rocky montane field environments of northern Goiás State.

A new species of Crossodactylodes (Anura: Leptodactylidae) from Minas Gerais, Brazil: first record of genus within the Espinhaço Mountain Range.

The genus Crossodactylodes comprises three species of Atlantic Rainforest endemic frogs strictly dependent on bromeliads where they spend their entire life cycle. The current geographic distribution of the genus covers highland areas of Atlantic Rainforest in the States of Rio de Janeiro and Espírito Santo, Southeastern Brazil. We describe a new species of the genus from Parque Estadual do Pico do Itambé, at Santo Antônio do Itambé municipality, State of Minas Gerais, Southeastern Brazil. Crossodactylodes itambe sp. nov. is characterized by the following combination of traits: male SVL 16.2 ± 1.3 (14.0-17.6 mm, n = 10), female SVL 16.2 ± 1.0 (13.5-18.0 mm, n = 15); snout short, rounded in dorsal view, sloping in lateral view; absence of vocal sac and vocal slits in males; absence of vomerine teeth; males with upper arms and forearms hypertrophied; cloacal flap prominent, simple; dorsal skin coarsely granular. The new species inhabits rupicolous bromeliads in open areas of rocky fields, and is recorded in altitudes between 1836 and 2062 m above sea level. This record extends the genus distribution for about 325 km northwest from where it was known. Crossodactylodes sp. nov. is the only species of the genus that occurs in open field habitats (campos rupestres), in very high altitudes of a non-costal mountain range (the Espinhaço Range).

Species Diversity and Temporal Variation of the Orchid-Bee Fauna (Hymenoptera, Apidae) in a Conservation Gradient of a Rocky Field Area in the Espinhaço Range, State of Minas Gerais, Southeastern Brazil.

This study investigated the orchid-bee community in a conservation gradient of the high-altitude rocky fields in the state of Minas Gerais, Brazil. Sampling was performed at two sites with different anthropic influences: a disturbed area (DA), with exotic plant species, and a preserved area (PA). From September 2009 through February 2011, males of euglossine bees were sampled using aromatic bait-traps. We collected a total of 819 specimens belonging to 11 species and three genera: Euglossa Latreille, Eulaema Lepeletier, and Eufriesea Cockerell. Despite the proximity of DA and PA (about 1.2km), differences in orchid-bee abundance and richness were observed. Higher abundance was observed in the PA (n = 485) compared with the DA (n = 334). Eight species were common to both sites, and only the DA showed exclusive species. The DA showed higher diversity and higher estimated species richness. Euglossa leucotricha Rebêlo & Moure was the most abundant species at both sites followed by Euglossa melanotricha Moure. Higher abundance and richness were found in the warm rainy season. This study contributes to the knowledge of the orchid-bee fauna in the rocky fields and suggests that the greater resource availability in the DA was responsible for the higher orchid-bee diversity.

Water stress and phenological synchronism between Copaifera langsdorffii (Fabaceae) and multiple galling insects: formation of seasonal patterns

The gall-induction rates in a population of the superhost Copaifera langsdorffii, located in a rocky field vegetation in Brazil, should follow sprouting events and water availability. The presence or absence of leaf flushing, the activity index for the vegetative phenophases, and the water potential were used to test this hypothesis, and ordination via canonical correspondence analysis was employed to test possible synchronisms. Based on 6881 sampled galls, three seasonal syndromes were observed for nine distinct morphotypes along a one-year cycle. The first syndrome related the decrease in the abundance of horn-shaped and cup-shaped galls with dry season. The second one revealed that other four morphotypes adjusted their cycles to leaf flushing, and the third syndrome involved three galls which occurred homogeneously along the year, with a tenuous peak of abundance in July. These syndromes reflect a strategy towards the occupation of distinct temporal niches on the same host plant.

Leaf morpho-anatomical variations in Billbergia elegans and Neoregelia mucugensis (Bromeliaceae) exposed to low and high solar radiation

The morpho-anatomical leaf structure may be directly affected by variations in the environmental conditions to which plants are exposed during development. The “campos rupestres” vegetation (rocky fields) is subjected to several stress conditions and microclimatic variations that result in important adaptations that enable the survival in these environments. In this study, we analyzed the leaf morpho-anatomy of two bromeliads, Billbergia elegans Martius ex Schultes f. and Neoregelia mucugensis Leme, occurring in the rock fields of Itacolomi State Park, southeastern Brazil, and tested for morpho-anatomical variations in response to light conditions. The analysis followed usual techniques in plant anatomy. Both species exhibited variations in the shape of the rosette, leaf color, and size of leaf sheath and blade. Scale density was higher on both leaf surfaces of individuals exposed to high solar radiation. Thickness of the leaf blade, water-storage parenchyma, chlorenchyma, and stomatal density were higher in individuals exposed to low solar radiation, which disagrees with most previous studies and may be related to the environment where these species occur, where water availability is one of the main limiting factors. Our observations point out a need for studies on herb species from xeric environments, which may bring new information on adaptations to these environments.