New Karyotypes and Some Considerations about the Chromosomal Diversification of Ctenomys minutus (Rodentia: Ctenomyidae) on the Coastal Plain of the Brazilian State of Rio Grande do Sul

The dominant mammals occupying the subterranean niche in South America are rodents of the genus Ctenomys, which form a large group of 56 species with chromosome numbers ranging from 2n= 10 to 70. In southern Brazil, Ctenomys minutus is the species with the widest geographic distribution, inhabiting sandy fields and dunes extending from Jaguaruna beach in the state of Santa Catarina to the town of São José do Norte in the state of Rio Grande do Sul. Eleven karyotypes (2n= 42; 2n= 46a; 2n= 46b; 2n= 47a; 2n= 47b; 2n= 48a; 2n= 48b; 2n= 49a; 2n= 49b; 2n= 50a and 2n= 50b) were described for this species and zones of hybridization are also known. A sample of 51 C. minutus specimens was collected from five sampling sites about 20 km apart along the coastal plain of Rio Grande do Sul between the municipalities of Tavares (31°23′S 51°09′W) and São José do Norte (31°52′S 51°54′W). We were able to extend the known geographic distribution of C. minutus by 90 km, from Tavares southwards to São José do Norte. During our study we found five karyotypes (2n= 46b, 47b, 48b, 49b and 50b), four of which (2n= 47b, 48b, 49b and 50b) have not previously been described for this species.     

Hisonotus devidei,a new species from the São Francisco basin,Brazil (Siluriformes: Loricariidae)

A recent expedition to headwaters of the Rio Pandeiros, a left‐bank tributary of the Rio São Francisco revealed the presence of a fourth species of Hisonotus from that basin. Hisonotus devidei sp. nov. differs from congeners by the presence of conspicuous dark blotches of distinct shapes irregularly arranged along lateral and dorsal surfaces of the body and scattered throughout all fins, by possessing small plates in lateral portions of the abdomen and adjacent areas between pelvic fins without development of dermal plates and by morphometric ratios. The putative phylogenetic placement of the new species is discussed based on morphological comparisons with species of related Hypoptopomatinae genera and the Hisonotus species diversity within the Rio São Francisco Basin is compared with that of adjacent basins.     

A new species of Centromochlus (Siluriformes,Auchenipteridae, Centromochlinae) from the middle Rio Tocantins basin,Brazil

A new species of the catfish genus Centromochlus (Auchenipteridae, Centromochlinae) is described. The new species is diagnosed by having numerous dark rounded blotches over the body and fins, dorsal‐fin spine with serrations anteriorly and smooth posteriorly, anal fin of mature males with three unbranched and seven branched rays, anterior nuchal plate absent and posterior nuchal plate not extended ventrally. The new species is described from a small stream in the Estação Ecológica Serra Geral de Tocantins, a natural reserve in the centre of the Brazilian Cerrado, close to the watershed between the Rio Tocantins and the Rio São Francisco basins. The new species is possibly the sister taxon to the recently described Centromochlus meridionalis from the upper Rio Tapajós. Those two species share with Centromochlus perugiae, from the upper Amazon and upper Paraguay, derived features associated with the modified anal fin in sexually mature males.     

Three new species,four new records and an updated checklist of Habenaria (Orchidaceae) from Rio Grande do Sul,Brazil

Three new species of Habenaria (Orchidaceae) section Nudae from Rio Grande do Sul, southern Brazil, are described and illustrated: Habenaria australis, H. kleinii and H. sobraliana. These are the first records of H. sect. Nudae for the state. Based on the examination of living and dried specimens, a total of 33 species and 400 collections of Habenaria were recorded for Rio Grande do Sul. Based on this survey, an updated checklist of the genus Habenaria for Rio Grande do Sul has been compiled. Four species are known only from this state, while seven other species are restricted to southern Brazil, Argentina and Uruguay. Habenaria hieronymi, previously known only from Argentina, is recorded for the first time from Brazil, and H. brachyphyton, H. ekmaniana and H. melanopoda are new records for Rio Grande do Sul.     

Two new species of cossonine weevils,Araucarius kuscheli spec. nov. and A. crassipunctatus spec. nov. (Coleoptera: Curculionidae) from southern Brazil

The occurrence of cossonine weevils of the genus Araucarius Kuschel 1966 is limited to South American Araucaria trees. Adults and larvae of two new species, Araucarius kuscheli spec. nov. and A. crassipunctatus spec. nov. have been found under the bark of Araucaria angustifolia trees in São Francisco de Paula, Rio Grande do Sul, Brazil. A key for the adults of the genus Araucarius including the two new species and the already known two Brazilian and four Chilean species is presented.     

Taxonomic review of Bourguyiinae,cladistic analysis,and a new hypothesis of biogeographic relationships of the Brazilian Atlantic Rainforest (Arachnida: Opiliones,Gonyleptidae)

The subfamily Bourguyiinae Mello‐Leitão, 1923 (Gonyleptidae) is revised, and both phylogenetic and biogeographic hypotheses are proposed. Bourguyiinae is monophyletic, and is the sister group of the remainder of the Gonyleptidae species used for analysis, except for the Metasarcinae, which collectively is the sister group of Metavononoides orientalis Mello‐Leitão, 1923 (Cosmetidae). Bourguyiinae is divided into two genera: Bourguyia (six species) and Asarcus (four species). The genus‐level synonyms proposed here are as follows: Caldasius, Styloleptes, and Stylopisthos are junior synonyms of Bourguyia; Bogdana, Cnemoleptes, and Opisthoplites are junior synonyms of Asarcus. The species synonyms proposed here are as follows: Afranius amarali Mello‐Leitão, 1934 is a junior synonym of Bourguyia albiornata Mello‐Leitão, 1923 ; Drastus hamatus Roewer, 1943 and Styloleptes conspersus Piza, 1943 are junior synonyms of Bourguyia trochanteralis Roewer, 1930 ; Asarcus corallipes Simon, 1879 , Asarcus lutescens Sørensen, 1884 , Asarcus pallidus Mello‐Leitão, 1923 , and Opisthoplites ypsilon Sørensen, 1884 are junior synonyms of Asarcus longipes Kollar in Koch, 1839 ; Asarcus nigriconspersus Soares & Soares, 1945 is a junior synonym of Asarcus ingenuus Melo‐Leitão, 1940. New species described are: Bourguyia bocaina sp. nov. (Serra da Bocaina, São José do Barreiro, São Paulo), Bourguyia vinosa sp. nov. (E.B. Boracéia, Salesópolis, São Paulo), and Asarcus putunaberaba sp. nov. (Parque Nacional do Caparaó, Alto Caparaó, Minas Gerais). Bourguyiinae is endemic to the Atlantic Rainforest in the Brazilian states of Minas Gerais, Rio de Janeiro, São Paulo, and Paraná. Based on the modified data matrix of Pinto‐da‐Rocha et al., we propose a new biogeographical hypothesis for the Atlantic Rainforest. We suggest that Bourguyiinae species were originally distributed from the coastal region of Paraná to the north of Rio de Janeiro and south‐east of Minas Gerais, with subsequent dispersals both to northern and southern areas. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 319–362.     

The Electric Glass Knifefishes of the Eigenmannia trilineata species‐group (Gymnotiformes: Sternopygidae): monophyly and description of seven new species

Eigenmannia trilineata López and Castello, 1966 (Sternopygidae) was described from the Río de La Plata basin and subsequently cited from most South American river basins. Questions about the limits of this species raise the possibility of the occurrence of undescribed species misidentified as E. trilineata. Herein we propose the Eigenmannia trilineata species group for species that share the presence of the superior medial stripe on the flank. This group comprises: E igenmannia antonioi sp. nov. , from the Rio Anapu, Rio Amazonas basin; E igenmannia desantanai sp. nov. , from the Rio Cuiabá, Rio Paraguay basin; E igenmannia guairaca sp. nov. , from the Riacho Água do Ó, upper Rio Paraná basin; E igenmannia matintapereira sp. nov. , from the Rio Uneiuxi and Rio Urubaxi, Rio Negro basin; Eigenmannia microstoma (Reinhardt, 1852), from the Rio São Francisco basin; E igenmannia muirapinima sp. nov. , from small tributaries of the Rio Amazonas; E igenmannia pavulagem sp. nov. , from the tributaries of Rio Capim, Rio Guamá basin; E. trilineata, from the lower Rio Paraná basin and Río de La Plata basin; Eigenmannia vicentespelaea Triques, 1996, from São Vicente I and II caves, Rio Tocantins basin; and E igenmannia waiwai sp. nov. , from the Rio Trombetas basin. These species can be distinguished from each other by unique sets of meristics, morphometrics, osteological and colour pattern features. © 2015 The Linnean Society of London     

Habitat use and nursery evaluation for the longnose stingray Hypanus guttatus (Bloch & Schneider, 1801) using vertebral microchemistry

Here, we use vertebral microchemistry to investigate the habitat use patterns of the longnose stingray Hypanus guttatus in the northern and northeastern regions of Brazil, and to evaluate the existence of potential nurseries of the species. Samples were collected in Maranhão, Rio Grande do Norte and Pernambuco states between 2008 and 2019. Trace element concentrations of Ba:Ca, Mg:Ca, Mn:Ca and Sr:Ca in vertebrae were determined through laser ablation inductively coupled plasma mass spectrometry. We used one-step permutational ANOVAs to evaluate multi and single-element differences in element:Ca ratios among life stages and sexes across and within sites. Element signatures differed among all sites for both single and multi-element settings. However, there were few differences among life stages within sites, except for Mn:Ca between life stages for Maranhão state, and between sexes for Sr:Ca for both Pernambuco and Rio Grande do Norte, and Ba:Ca for Rio Grande do Norte. Furthermore, all multi and single-element analyses across locations were significant and highlight the strong differences by sites. We also performed a nonmetric multidimensional scaling analysis, which demonstrated the strong differences for samples from Rio Grande do Norte and the other two sites. By analysing the lifetime transects of each sample, we observed that there was little variation in all element:Ca ratios within sites. Therefore, we argue that the longnose stingray likely does not display extensive habitat use shifts and fulfils much of its life cycle within each area. Finally, we obtained no evidence of nurseries for any site and suggest this is likely a pattern across the species distribution. Future studies investigating habitat use with samples from larger specimens (disc width > 90 cm, >15 years) are needed to better understand the species habitat use patterns across all size ranges.     

Karyotypes of two American field crickets: Gryllus rubens and Gryllus sp. (Orthoptera: Gryllidae)

The karyotypes of Gryllus rubens (Scudder) and Gryllus sp. collected in the US were studied using conventional Giemsa staining and two differential staining methods. Both species had a chromosome complement of 2n = 28 + XX/XO, and the X chromosome was large and metacentric. In addition, nucleolus organizer regions (NOR) were detected in the short arm of one pair in the two species, and the NOR showed variation in size. The two species had species‐specific chromosome configuration and C‐banding patterns. In Gryllus sp., the chromosome configuration showed polymorphism in size and type among individuals, and the distal C‐bands of Gryllus sp. were larger than those of G. rubens.     

Population expansion of the invasive Pomacentridae Chromis limbata (Valenciennes, 1833) in southern Brazilian coast: long-term monitoring,fundamental niche availability and new records

Human-mediated species invasions are recognized as a leading cause of global biotic homogenization and extinction. Studies on colonization events since early stages, establishment of new populations and range extension are scarce because of their rarity, difficult detection and monitoring. Chromis limbata is a reef-associated and non-migratory marine fish from the family Pomacentridae found in depths ranging between 3 and 45 m. The original distribution of the species encompassed exclusively the eastern Atlantic, including the Azores, Madeira and the Canary Islands. It is also commonly reported from West Africa between Senegal and Pointe Noire, Congo. In 2008, vagrant individuals of C. limbata were recorded off the east coast of Santa Catarina Island, South Brazil (27° 41′ 44″ S, 48° 27′ 53″ W). This study evaluated the increasing densities of C. limbata populations in Santa Catarina State shoreline. Two recent expansions, northwards to São Paulo State and southwards to Rio Grande do Sul State, are discussed, and a niche model of maximum entropy (MaxEnt) was performed to evaluate suitable C. limbata habitats. Brazilian populations are established and significantly increasing in most sites where the species has been detected. The distributional boundaries predicted by the model are clearly wider than their known range of occurrence, evidencing environmental suitability in both hemispheres from areas where the species still does not occur. Ecological processes such as competition, predation and specially habitat selectivity may regulate their populations and overall distribution range. A long-term monitoring programme and population genetics studies are necessary for a better understanding of this invasion and its consequences to natural communities.     

Predicting the current distribution and potential spread of the exotic grass Eragrostis plana Nees in South America and identifying a bioclimatic niche shift during invasion

Eragrostis plana (Poaceae) is a perennial grass introduced from South Africa to the state of Rio Grande do Sul in southern Brazil. Currently, it is considered an invasive grass in several regions of the world, including South America, where it has caused negative ecological and socio‐economic impacts. Ecological niche models, using bioclimatic variables, are often used to predict the potential distribution of invasive species. In this study we prepared two bioclimatic models for E. plana using the Genetic Algorithm for Rule‐set Production, the first based on data from its native region (South Africa) and the second on data from both the native and invaded (South America) regions. We then projected each model onto South America to identify regions vulnerable to invasion by the species, and compared our results with available records of the species in South America. Finally, we explored the model's predictions for the existence of a bioclimatic niche shift during the invasion process of E. plana in South America, using multivariate statistical analysis. The model created with native distribution data was only able to predict (with highly suitable habitat) the region of introduction of E. plana in South America. However, the current distribution, as well as the region of introduction of the species, was reliably predicted by the model created with data from both native and invaded regions. Our multivariate analysis supports a hypothesis of bioclimatic niche shift during the invasion process of E. plana in South America.     

Chromosomal rearrangements as the source of variation in the number of chromosomes in Pseudis (Amphibia, Anura)

A cytogenetic study of Pseudis specimens from three localities in Rio Grande do Sul State, the southernmost Brazilian, was performed to identify karyotypic characteristics that could account for differences in vocalization pattern and body size. Individuals from around Tainhas were compared to those of São Jerônimo and Eldorado do Sul. Specimens from these latter two localities were identified as Pseudis minuta, while those from the former were classified as Pseudis sp. (aff. minuta). The populations from São Jerônimo and Eldorado do Sul had 2n?=?24 chromosomes, classified as metacentric, submetacentric and subtelocentric. The population from Tainhas had 2n?=?28 chromosomes, with four pairs of telocentric chromosomes. Modelling of these 28 chromosomes and testing for fusion in the centromeric/telomeric regions yielded a karyotype of 2n?=?24 chromosomes, similar to that of the other populations. The similarity was reinforced by the location of the NORs and heterochromatin. The Tainhas population showed an increase in heterochromatin, as seen by the presence of additional C-bands, especially in the telocentric chromosomes. These data suggest that the two karyotypes described in this work had a common ancestry. There is evidence that the differentiation of these karyotypes may have occurred by chromosome fission and heterochromatin addition. Based on the present karyotype (2n?=?28) and on morphological and vocalization studies by other researchers, we conclude that the Tainhas population may represent a new species.     

A new species of Astyanax (Characiformes: Characidae) from Dolina Água Milagrosa,Rio Paraguai basin,Mato Grosso,Brazil

A new species of Astyanax is described from the upper Rio Paraguai basin, Mato Grosso State, Brazil. The new species can be distinguished from congeners by having the body intensely yellowish in life (v. silvery, reddish or lightly yellow) and by morphometric and meristics traits. Astyanax dolinae n. sp. cannot be assigned to any of the Astyanax species complex currently recognized for the genus. It is only known from the Dolina Água Milagrosa, a karstic sinkhole lake, entirely fed by groundwater, surrounded by Cerrado, the savannah‐like vegetation of central South America.     

An ethnobiological assessment of Rumohra adiantiformis (samambaia-preta) extractivism in Southern Brazil

The fronds of Rumohra adiantiformis, also known as ‘7-weeks-fern,’ ‘leatherleaf’ or ‘samambaia-preta,’ are used worldwide as florists’ greenery. Costa Rica and the USA cultivate and export R. adiantiformis, whereas in South Africa and Brazil this trade is based on extractivism. In Brazil, R. adiantiformis is harvested in the Atlantic Forest biome; 50% of the production comes from the slopes of the ‘Serra Geral’ (state of Rio Grande do Sul), where some 2000 families harvest and trade R. adiantiformis as their main source of revenue. However, harvesting, trading and transporting wild ornamental species is illegal in the Atlantic Forest, This study evaluates R. adiantiformis extractivism in hilly areas of Rio Grande do Sul, from an ethnobotanical/ethnoecological perspective. The study reveals that emic perceptions on the sustainability of R. adiantiformis extractivism are in agreement with relevant ecological data. The regeneration areas on the slopes of the Serra Geral have the highest plant density ever reported for R. adiantiformis; its extractivism has low environment impact and generates significant income for local communities. Further studies of these areas are important in order to support neoextractivism as a suitable form of use of the state's biodiversity.     

Geographic distribution and food habits of Leopardus tigrinus and L. geoffroyi (Carnivora,Felidae) at their geographic contact zone in southern Brazil

The objective of this study is to define the geographic distribution of Leopardus tigrinus and L. geoffroyi in one of the few regions of South America where they co-occur, the state of Rio Grande do Sul (RS), in southernmost Brazil. We compiled 133 records for both species and constructed a distribution map, which shows sharp geographic segregation between them. Leopardus tigrinus was found to be associated more with forested ecoregions in the northern part of the state, while L. geoffroyi records were mainly associated with open habitats of the Pampas biome in southern RS. We present data on the diet of these two species that indicate trophic niche separation between them in this region of geographic contact. Our results thus suggest that these species exhibit ecological partitioning with respect to habitat and prey, and that these factors may influence the observed pattern of limited spatial overlap in this region.     

South American electric knifefishes of the genus Archolaemus (Ostariophysi,Gymnotiformes): undetected diversity in a clade of rheophiles

Neotropical electric knifefishes of the family Sternopygidae previously considered to represent a single relatively geographically widespread and morphologically variable species, Archolaemus blax, were analysed and found to represent a complex of five species, four of which are new to science. A fifth undescribed species from the Rio São Francisco basin outside the previous known range of the genus was identified. Recognized species of Archolaemus are: A. blax, previously thought to occur in the Rio Araguari, Rio Branco, Rio Tapajós, Rio Tocantins, and Rio Xingu, but which instead proved to be endemic to the Rio Tocantins; Archolaemus ferreirai sp. nov. from the Rio Mucajaí and Rio Uraricoera in the north‐eastern portions of the Amazon basin; Archolaemus janeae sp. nov. of the Rio Xingu and the upper Rio Tapajós, both southern tributaries of the mainstream Amazon; Archolaemus luciae sp. nov. of the Rio Trombetas, Rio Jari, and Rio Tapajós basins of the eastern Amazon, and the independent Rio Araguari draining into the Atlantic Ocean north of the mouth of the Amazon; Archolaemus orientalis sp. nov. of the São Francisco basin in eastern Brazil; and Archolaemus santosi sp. nov. of the Rio Jamari in the south‐western portion of the Amazon basin. The phylogenetic placements of Archolaemus and the recently described genus Japigny relative to the other members of the Eigenmanninae are discussed. A series of synapomorphies for Archolaemus are proposed and a hypothesis of the relationships within that genus is advanced. Rheophily of all members of Archolaemus is discussed, with the genus found to be the most specious clade within the Gymnotiformes living primarily in high‐energy settings. The reported anterior projection of the dentary teeth in A. blax was found to be a consequence of postmortem displacement.     

Primitive nest architecture and small monogynous colonies in basal Attini inhabiting sandy beaches of southern Brazil

The species Mycetophylax conformis, M. simplex and Cyphomyrmex morschi, all belonging to the basal Attini, occur exclusively on beaches along the Atlantic shores of South America. In Brazil C. morschi colonies were found sympatrically with the two Mycetophylax species which, however, had no overlap in their geographic distribution. We recorded species‐specific nesting site preferences resulting in a zonal colonization of dune and restinga areas, with distinct preferences in microhabitat choice. After excavating subterraneous nests, we were able to describe details of nest architecture, especially with regard to the number and position of the fungus chambers. The nest structure is similar in all species, but the colony size differed with the highest number of workers in M. simplex. All nests were headed by a single mated queen. First attempts were undertaken to maintain colonies under laboratory conditions.

Resumo

As espécies Mycetophylax conformis, M. simplex e Cyphomyrmex morschi fazem parte do grupo dos Attini basais e ocorrem exclusivamente em praias do Atlântico na América do Sul. No Brasil C. morschi ocorre simpatricamente com as espécies de Mycetophylax, mas as duas espécies de Mycetophylax não tem uma sobreposição na sua distribuição geográfica. Também detectamos preferências específicas na escolha da área da nidificação o que resulta em uma colonização zonal das dunas e restingas com preferências distintas na escolha do microhabitat. Com escavações cuidadosas de um número representativo de ninhos obtivemos detalhes sobre a arquitetura, em especial o número e posição das câmaras de fungo. A estrutura subterrânea dos ninhos é similar nas espécies estudadas mas o tamanho da população difere entre as espécies com o maior número de operárias em M. simplex. Todas as colônias tem uma rainha que copulou apenas uma única vez. Primeiras tentativas de manutenção de colônias no laboratório foram feitas.     

On the spread of the Russian sturgeon Acipenser gueldenstaedtii (Acipenseriformes: Acipenseridae) in the Neotropics: A marine path to invade freshwater drainages in South America?

Acipenser gueldenstaedtii is a species of sturgeon described from Caspian Sea and Black Sea and their tributaries, occurring in the Eastern Atlantic, Europe and Middle East. This and other two sturgeon species have been accidentally introduced in the Rio Negro, Uruguay, a tributary of the Rio de La Plata. Recently, it has been demonstrated the presence and establishment of A. gueldenstaedtii widespread in the Rio Paraná basin, the largest tributary of the Rio de La Plata, corresponding to the second largest river drainage in the Neotropics. We herein register the presence of the species in the next northern freshwater drainage in South America, representing the first record for Brazil. We further discuss the possibility of dispersal through marine environments to other freshwater drainages in South America through the analysis of its documented occurrence and marine ecoregions in southwestern Atlantic.     

The Association of Two Gall Crabs (Brachyura: Cryptochiridae) with the Reef-building Coral Siderastrea stellata Verrill, 1868

The family Cryptochiridae includes a small group of cryptic crabs that inhabit cavities in scleractinian corals. They are represented in Brazil by two species. Troglocarcinus corallicola, found from Maranhão to Bahia states and that occurs in many species of the coral families Mussidae, Faviidae, Caryophillidae and Siderastreidae. Opecarcinus hypostegus, reported from the state of Pernambuco, is mainly associated with Agaricia fragilis. The range of O. hypostegus is extended to Rio Grande do Norte and Alagoas states. Males are usually smaller than females, and couples may be eventually found sharing cavities. Ovigerous females and males of O. hypostegus are recorded for the first time inhabiting adjoining cavities on colonies of Siderastrea stellata, an endemic reef coral widespread along the Brazilian littoral.