Population ecology of Trichomycterus itacarambiensis, a cave catfish from eastern Brazil (Siluriformes, Trichomycteridae)

The population ecology of the trichomycterid catfish, Trichomycterus itacarambiensis, from the Olhos d'Àgua Cave, Itacarambi Co., Minas Gerais, eastern Brazil, was investigated by the mark-recapture method during the dry season of 1994 (April to October). The cave is subject to a pronounced seasonality, and is flooded during part of the rainy period. All individuals captured along the 5000 m long stream gallery (divided in 50 sections) were marked by tattooing, measured and examined for the degree of pigmentation reduction. About one third of the population is truly albinic; the remainder may exhibit partial depigmentation. After five bimestrial collections, 583 specimens have been marked, of which 150 were recaptured at least once. Estimated population size was 1500–2000 individuals longer than 20 mm SL. The total population size of T. itacarambiensis is considered small when compared to those of epigean trichomycterids and of other studied cavefishes as well. Mean population density was 0.15–0.20 individuals m^-2 throughout the dry season; it increased with the distance to the stream resurgence, probably due to the higher food availability upstream. This population density may be considered intermediate to those of other troglobitic fishes. Most recaptures (66%) were done in the same section as the previous capture. Active movements, both upstream and downstream, were recorded up to distances of 600 m; a few possibly passive, downstream movements covered distances from 900 to 1500 m. T. itacarambiensis catfishes move more frequently and for longer distances than the Brazilian blind pimelodids, Pimelodella kronei. Individual growth in T. itacarambiensis probably occurs in pulses, during the rainy seasons; interruption of growth in the dry season is attributed to the pronounced food shortage. The mean longevity was estimated as seven years. Differences between pigmented and albino individuals include a higher frequency of downstream movements and slightly higher growth rates in the latter.     

Habitat and Population Data of Troglobitic Armored Cave Catfish, Ancistrus Cryptophthalmus Reis, 1987, from Central Brazil (Siluriformes: Loricariidae)

Population ecology of the troglobitic armored catfish, A. cryptophthalmus, from caves in São Domingos karst area of central Brazil, was studied in a two-census capture-mark-recapture study carried out during the dry season of 1999. Like many loricariids, including epigean Ancistrus catfishes from that area, A. cryptophthalmus is a typical bottom-dweller with a strong preference for rocky substrates in fast-flowing stream sectors. Relatively high population densities, when compared to other cavefishes, were recorded in the studied cave sections: 0.9 individuals m^–2 in Angélica Cave and 0.5 individuals m^–2 in Passa Três Cave. Passa Três Stream is a small tributary of the São Vicente Cave system, and the estimated population for Passa Três Cave (ca. 2000 m long) is around 1000 individuals. On the other hand, the large Angélica Cave Stream (8 km long) harbors a very large population, conservatively estimated at 20 000 individuals. No fish movements of distances longer than 100 m were recorded in the 40-day period. In Passa Três Cave, a few movements of distances up to 60 m were detected. Proportion of mature females in Angélica Cave was higher than in Passa Três Cave, possibly reflecting a greater food availability in the first cave. Mean individual growth rates in Angélica Cave (1.35 mm month^–1 for size class <41 mm SL, 0.17 mm month^–1 for size class >41 mm SL) point to relatively high longevities, possibly attaining 15 years.     

Hypostomus sertanejo (Siluriformes: Loricariidae), new armoured catfish species from north‐eastern Brazil

A re‐evaluation of the armoured catfish species of Hypostomus in the Rio Jaguaribe, north‐eastern Brazil, was prompted by the discovery of specimens with pale spots on a dark background collected from that basin c. 1936 and deposited at the Academy of Natural Sciences of Philadelphia. Recent field collections in the Rio Jarguaribe basin confirmed the presence of the pale‐spotted specimens and its distinctiveness as a new species. Hypostomus sertanejo n. sp. is diagnosed from other species of Hypostomus by having fins and dermal‐plated regions of head and body with pale spots or vermiculations on darker background, teeth slender, asymmetrically bicuspid and numerous (34–75) on dentary and premaxilla, depressed dorsal‐fin spine not reaching adipose spine, unbranched pectoral‐fin spine longer than unbranched pelvic‐fin ray, seven branched dorsal‐fin rays and one (rarely two) predorsal plate(s) bordering supraoccipital. Ancistrus salgadae Fowler 1941 is hypothesized to be a junior synonym of Hypostomus carvalhoi (Miranda‐Ribeiro, 1937), a dark‐spotted Hypostomus described from the Rio Granjeiro, a tributary to the upper Rio Salgado.     

Neoplecostomus doceensis: a new loricariid species (Teleostei,Siluriformes) from the rio Doce basin and comments about its putative origin

A new species of Neoplecostomus is described from the rio Doce basin representing the first species of this genus in the basin. The new species is distinguished from its congeners by having enlarged, fleshy folds between dentaries, two or three series of developed papillae anterior to premaxillary teeth and a adipose-fin membrane present, and by lacking enlarged odontodes along snout lateral margins in mature males, a well-developed dorsal-fin spinelet wider than dorsal-fin spine base, lower number of lateral-line figs and developed membrane on the dorsal portion of the first, second and third pelvic-fin branched rays. Additionally, we present a brief discussion of biogeographic scenarios that may explain the distribution of the new species in the rio Doce basin. We suggested that the ancestral lineage of the new species reached the rio Doce from the upper portions of rio Paraná drainages about 3.5 Mya (95% HPD: 1.6–5.5) indicating a colonization route of the N. doceensis ancestral lineage from the south end of Serra do Espinhaço, probably as a result of headwater capture processes between the upper rio Paraná and rio Doce basins.     

Two new species of Pseudancistrus (Siluriformes,Loricariidae) from the Amazon basin,northern Brazil

Two new species of Pseudancistrus, a genus diagnosed by non-evertible cheek plates and hypertrophied odontodes along the snout margin, are described from two drainages of the Brazilian Shield: Pseudancistrus kayabi from the rio Teles Pires (rio Tapajós basin) and Pseudancistrus asurini from the rio Xingu. The new species are distinguished from congeners (Pseudancistrus barbatus, Pseudancistrus corantijniensis, Pseudancistrus depressus, Pseudancistrus nigrescens, Pseudancistrus reus, and Pseudancistrus zawadzkii) by the coloration pattern. Pseudancistrus kayabi has dark bars on the dorsal and caudal fins which are similar to that of Pseudancistrus reus from the Caroní River, Venezuela. Pseudancistrus asurini is unique among Pseudancistrus in having whitish tips of the dorsal and caudal fins in juveniles to medium-sized adults.     

Genetic characterization of the Neotropical catfish Pimelodus maculatus (Pimelodidae,Siluriformes) in the Upper Uruguay River

Freshwater fish present unique challenges when one attempts to understand the factors that determine the structure of their populations. Habitat fragmentation is a leading cause of population decline that threatens ecosystems worldwide. In this study, we investigated the conservation status of genetic variability in the Neotropical catfish (Pimelodus maculatus). Specifically, we examined the structure and genetic diversity of this species in a region of the Upper Uruguay River fragmented by natural barriers and dams. There was no genetic structure among the four sites analyzed, indicating the existence of only one population group. A combination of environmental management and genetic monitoring should be used to minimize the impact of impoundment on panmitic populations of migratory fish species.     

Parotocinclus jacksoni,a new hypoptopomatine catfish (Siluriformes: Loricariidae) from the Rio Mamanguape basin,north-eastern Brazil

A new species of Parotocinclus is described from the Rio Mamanguape basin, in the State of Paraíba, north-eastern Brazil. The new species can be distinguished from all of its congeners, except for P. bahiensis, P. cesarpintoi, P. jumbo, P. nandae and P. spilosoma, by the presence of an abdomen covered by a few small and dispersed platelets (vs. an abdomen entirely covered by large plates in adult individuals or the absence of plates in that region). The new species differs from those mentioned above with respect to several features, such as an exposed pectoral girdle and supporting odontodes medially and laterally, the number of premaxillary and dentary teeth, odontodes covering only the lateral portion of the cleithrum and the absence of irregular golden lines on the head and body (colour in vivo). The new species was collected only in the upper and middle portions of the Rio Mamanguape basin, suggesting a geographic distribution restricted to the Caatinga biome.     

Behaviour,feeding habits and ecology of the blind catfish Phreatobius sanguijuela (Ostariophysi: Siluriformes)

The subterranean fish Phreatobius sanguijuela, originally described from Bolivia, was captured in different wells near São Francisco do Guaporé, Rondônia State, Brazil. Thirty wells were investigated in April and July 2012, and September 2013. These surveys resulted in the capture of 58 individuals from eight wells and comprised three to 14 individuals per well. The capture of the individuals allowed a detailed evaluation of their colours in life, behaviour in the field and in captivity, aspects of their biology, confirmation of the species identification and provided new diagnostic characteristics to distinguish between P. sanguijuela and Phreatobius dracunculus. Cannibalism, territorialism, agonistic interactions and phototaxis behaviour were not observed. Phreatobius sanguijuela exhibited cryptobiotic habits and two behaviours under stressful conditions. The analysis of stomach contents reveals that this species apparently feeds on invertebrates, almost exclusively on earthworms. The sex ratio was 1:1. The absence of opercular movement during the resting period associated with intense blood irrigation of the skin indicates a possible cutaneous respiration as an alternative form of gas exchange. Local people often mistake P. sanguijuela for helminths and have the habit of releasing non‐native fishes into the wells or to use chemicals to eliminate them. The consequence of this habit for the conservation of the species requires further evaluation.     

Food and reproduction of Trichomycterus itacarambiensis, cave catfish from south-eastern Brazil

Trichomycterus itacarambiensis is a troglobitic (cave-restricted) catfish found in the Olhos ďÁgua Cave, Itacarambi Co., Minas Gerais, south-eastern Brazil. The cave is subject to a pronounced seasonality, and is flooded during part of the rainy season. The pigmentation degree is variable in T. itacarambiensis , a third of the population being true albinos; the eyes vary from normal to externally invisible. As expected for a cave-dwelling fish, T. itacarambiensis is a carnivorous generalist, which preys mainly on autochthonous insects and earthworms. It is a chemically oriented predator of bottom and surface animals, using foraging tactics also used by other cave catfishes, such as the pimelodids Pimelodella kronei and Imparfinis sp. However, bottom feeding seems to be more important for T. itacarambiensis than for the latter. There is a severe feeding stress during the dry season, when few individuals are able to get food. Reproduction is seasonal, with increased reproductive activity at the end of the rainy period, as recorded for Imparfinis sp., also a species living in a semi-arid region with a well-defined dry season. It is estimated that up to 50% of the female T. itacarambiensis can reproduce every year, a high proportion for a troglobitic fish species. At least during the study period, pigmented individuals reproduced more frequently than the albinos.     

Population Dynamics and Diet of the Madamango Sea Catfish Cathorops spixii (Agassiz, 1829) (Siluriformes: Ariidae) in a Tropical Bight in Southeastern Brazil

The madamango sea catfish, Cathorops spixii (Siluriformes: Ariidae), is often among the most abundant fishes on the South American Atlantic coast. In the present study, conducted in shallow, non-estuarine coastal areas of Caraguatatuba Bight in southeastern Brazil, collections of this species, the most abundant member of the ichthyofauna, included primarily medium-sized individuals, indicating that the area may play a specific role in their development. Although studies of the local ichthyofauna have been much neglected, the area is economically important and its ecological significance is undervalued. This study primarily treats habitat use by C. spixii, assessing certain population parameters and the dietary composition. Monthly samples were taken from August 2003 through October 2004, with three trawls in two areas, corresponding to depths of about 1 to 4 m. The catfish showed two main peaks of abundance in the area, in April/May and July 2004. A mode around 9 cm SL persisted through time, and the entrance of younger recruits peaked from January to April. The low estimate for body-growth parameters (K = 0.16) corroborates some K-strategist characteristics of the species. The asymptotic length was 27.3 cm SL and total mortality (Z) was 1.01 yr⁻¹. Cathorops spixii showed an omnivorous feeding habit, preying mainly upon polychaetes, copepods and bivalves, with considerable seasonality in its diet.     

Changes in Anuran Species Richness and Abundance Resulting from Hydroelectric Dam Flooding in Central Brazil

River damming causes ecosystem losses and habitat fragmentation. In the Cerrado, the flood affects mainly forested habitats in valleys. In 1996, the Tocantins River (Brazil) was dammed to create the Serra da Mesa hydroelectric plant, and 14 sites were monitored during flooding. Eight hills that formed islands were monitored with pitfall traps. Only one frog species was found on islands 3 yr after complete reservoir formation. Cerrado amphibians showed rapid decline during and after flooding.     

Nesticus baeticus sp. n., a new troglobitic spider species from south-west Europe (Araneae, Nesticidae)

We describe a new species of carcinoecium-forming sea anemone, Stylobates birtlesisp. n., from sites 590-964 m deep in the Coral Sea, off the coast of Queensland, Australia. An anemone of this genus settles on a gastropod shell inhabited by a hermit crab, then covers and extends the shell to produce a chitinous structure termed a carcinoecium. Stylobates birtlesisp. n. is symbiotic with the hermit crab Sympagurus trispinosus (Balss, 1911). The nature of marginal sphincter muscle and nematocyst size and distribution distinguish Stylobates birtlesi sp. n. from other species in the genus. The four known species of Stylobates are allopatric, each inhabiting a separate ocean basin of the Indo-West Pacific. We also extend the known range of Stylobates loisetteae in the Indian Ocean off the coast of Western Australia.     

Amblyceps crassioris,a new sisoroid catfish from Odisha,India (Siluriformes: Amblycipitidae)

Amblyceps crassioris, a new species of amblycipitid catfish, is described from the Mahanadi River basin in Odisha, India. The new species can be distinguished from its congeners in having a combination of the following characters: a deeply forked caudal fin, centrally projecting hooks on proximal lepidotrichia of median caudal-fin rays absent, jaws equal in length, lateral line absent, body depth at anus 15.1%–19.5% standard length (SL), caudal peduncle depth 13.0%–18.3% SL, adipose-fin base length 21.1%–27.1% SL, eye diameter 7.35%–14.1% head length and 38 total vertebrae.     

A new species of Scolopocryptops Newport: a troglobitic scolopocryptopine centipede from a remarkable siliciclastic area of eastern Brazil (Scolopendromorpha,Scolopocryptopidae, Scolopocryptopinae)

We describe Scolopocryptops troglocaudatus sp. n., a new troglobitic scolopocryptopine centipede species. The species was found in a remarkable siliciclastic karst area of Eastern Brazil, in three caves of the Chapada da Diamantina, in the state of Bahia. Scolopocryptops troglocaudatus sp. n. is close to Scolopocryptops miersii Newport, 1845 and Scolopocryptops ferrugineus macrodon (Kraepelin, 1903) but differs from them by troglomorphic features, such as depigmentation, long appendages and a thin cuticle. This new species is the second troglobitic scolopocryptopine described and is the first discovered in Brazil.     

The first troglobitic species of freshwater flatworm of the suborder Continenticola (Platyhelminthes) from South America

Brazilian cave diversity, especially of invertebrates, is poorly known. The Bodoquena Plateau, which is located in the Cerrado Biome in central Brazil, has approximately 200 recorded caves with a rich system of subterranean water resources and high troglobitic diversity. Herein we describe a new troglobitic species of Girardia that represents the first obligate cave-dwelling species of the suborder Continenticola in South America. Specimens of the new species, which occur in a limestone cave in the Bodoquena Plateau, in the Cerrado biome, are unpigmented and eyeless. Species recognition in the genus Girardia is difficult, due to their great morphological resemblance. However, the new species can be easily recognized by a unique feature in its copulatory apparatus, namely a large, branched bulbar cavity with multiple diverticula.     

Phylogeny and species diversity of Tasmanian mountain shrimps and their relatives (Crustacea,Anaspidesidae)

Anaspidacea is an enigmatic taxon within Malacostraca with uncertain phylogenetic affinities. One of the four families within Anaspidacea, the Anaspidesidae (representing in most respects the plesiomorphic conditions of the entire taxon), is endemic to Tasmania and shows a remarkable geographical and vertical distribution. Eleven species in three genera (Allanaspides, Anaspides and Paranaspides) are recognized to date, occurring in freshwater habitats such as lakes, rivers, streams, tarns and also in caves. We present the most detailed analyses to date of the phylogeny of Anaspidesidae including all eleven species based on molecular data (COI, 16S and 28S). In addition, the genetic differentiation within the morphologically recognized species is studied and a dating of speciation is given using a molecular clock approach (based on mt‐DNA only). A special focus is on the multiple instances of immigration into the subterranean habitat. Most of the morphologically delineated species are recognized by molecular data. Significantly, however, in at least two cases, the molecular data suggest more species than so far described, but further molecular sampling from a wider range of localities is required. Our molecular divergence estimates suggest the anaspidesids are younger than previously thought. Rather than having Eocene origins, our results suggest Early Miocene origins with primary diversification in Miocene and Pliocene. Entry into subterranean habitats appears to have occurred in the Pleistocene rather than Tertiary. Thus, rather than being a defensive response to rising temperatures in the Tertiary, entry into caves in the Pleistocene may represent opportunistic expansion into new habitats created by the action of glacial meltwaters on existing karst formations. As a result, environmental changes during the Pleistocene appear to have prompted ecological expansion of Anaspides by “opening” new subterranean habitats leading to increased diversification in the group.     

Population ecology ofGoniosoma spelaeum, a cavernicolous harvestman from south-eastern Brazil (Arachnida: Opiliones: Gonyleptidae)

Goniosoma spelaeum (Mello-Leitão) is a widespread trogloxene harvestman in caves of the Ribeira Valley in São Paulo State. It inhabits walls and ceilings near cave entrances. Populations inhabiting six selected caves of the region were analysed during this study. Mark-recapture techniques were used to estimate population sizes. Populations vary from tens to hundreds of individuals in each cave, and vary throughout the year. Barra Bonita cave had the largest population and was used to identify other ecological features of the species. These harvestmen show a high degree of philopartry, and recapture rate was high. They remain motionless inside the caves during the day, leaving them after dark to forage, and return just after dawn. They always feed outside the caves and do not carry food into the caves. Soft-bodied insects were the main food observed in the field. In the laboratory, they accepted plant and animal items and industrial foods. Their main predators are the spider Ctenus fasciatus , the heteropteran Zelurus travassosi , and the marsupial Philander opossum , and their main parasites are dipteran larvae (probably Phoridae).     

Habitat use and behavioural ecology of the juveniles of two sympatric damselfishes (Actinopterygii: Pomacentridae) in the south-western Atlantic Ocean

Spatial distribution, microhabitat use and territorial and feeding behaviours were compared between the juveniles of two sympatric territorial damselfishes Stegastes variabilis and Stegastes fuscus on a small tropical reef in the south-western Atlantic Ocean. Juvenile S. variabilis were most abundant at sites subject to stronger hydrodynamics and with mixed benthic cover, whereas juvenile S. fuscus were most abundant at sheltered sites with dense turf algae cover. No differences regarding feeding habits were detected, with both species preferentially feeding on turf algae. Also, despite similarities in territory area and agonistic encounter rates, the identity and proportion of intruders involved in agonistic interactions differed significantly between species. These interdependent traits suggest strong asymmetric competition, with juvenile S. fuscus dominating high-quality sites and evicting juvenile S. variabilis to low quality, marginal areas of the reef.