The occurrence of facultative paedomorphosis in a lacustrine population of the Pyrenean newt (Calotriton asper): morphology and age structure

Facultative paedomorphosis is a common polyphenism in newts where two alternative phenotypes can coexist: metamorphs and paedomorphs (mature with larval traits, i.e. retaining gills). This phenomenon has been reported in some lacustrine populations of the Pyrenean newt (Calotriton asper). The morphology and life-history traits were studied in a lacustrine population of this species with the occurrence of facultative paedomorphosis. The results showed that 24.3% of adults retained gills at different levels of reabsorption and had a smoother skin compared with the other populations, which were fully metamorphic. The body size and shape showed significant sexual differences, with males being larger than females. The presence of paedomorphic traits also affected the body size and shape, revealing a complex pattern of growth in which metamorphic adults were larger than paedomorphs. The age structure was different between sexes, with a median age of 10.5 and 7 years and longevity of 19 and 14 years in males and females, respectively. Considering each sex separately, the age structure was not significantly different between metamorphic and paedomorphic newts. In addition, metamorphosed and branchiate juveniles were found with a maximum age of 13 and 20 years, respectively. Remarkably, long-lived larvae with an exceptional individual of 18 years were found, which has not previously been reported in any other newt species. The mechanisms that can explain the evolution of paedomorphosis are complex and comprise the interaction of multiple factors related to the cost of reproduction and growth.     

Life cycle and population structure of the terrestrial isopod Hemilepistus klugii (Brandt, 1833) (Isopoda: Oniscidea) in Iran

The life cycle and population structure of Hemilepistus klugii were studied in a population in Varamin, Iran. The population was sampled monthly (or fortnightly during the breeding season) from February 2008 to June 2009 and a total of 7015 individuals, comprising 1069 males, 1079 females and 4867 juveniles, were collected. As in other Hemilepistus species, five distinct phenophases, namely pair formation, gestation, hatching, growth and stationary, were recorded during the life cycle of H. klugii. The overall sex ratio was 1 : 1 but varied over time. Ovigerous females were observed only in April, indicating a seasonal and very short breeding period. With a short lifespan after breeding, females demonstrated true semelparity. The mean cephalothorax width for ovigerous/post-ovigerous females was higher in 2008 than in 2009. These females attained the largest size in the population throughout the year. The number of eggs per female ranged from 28 to 147 (mean ± SE, 78 ± 1.8). There was a positive correlation between female size and fecundity. Recruitment occurred in late April and resulted in the highest population density in this month, whereas the lowest densities were observed during November to January. Despite a high percentage of ovigerous females carrying undeveloped eggs (72.3%), intramarsupial mortality was low (3.5%).     

Reproductive ecology of the glass frog Espadarana prosoblepon (Anura: Centrolenidae) in an urban forest of the Central Andes of Colombia

Population and reproductive behaviour aspects of the glass frog Espadarana prosoblepon are well known for populations from Central America, but similar information is lacking for populations from South America. We recorded the reproductive ecology of a population of the glass frog E. prosoblepon in the city of Armenia, Central Andes of Colombia. With weekly surveys with mark-recapture between December 2013 and November 2015, we monitored activity patterns and evaluated if the probability of males mating is associated to their body size or to chorus tenure (i.e. the number of nights a same individual is calling for attracting a mate). In addition, upon observing an amplexus, we recorded the behaviour of the individuals until oviposition and noted characteristics of egg clutch. We recorded 47 males and 32 females, nine amplexus events, eight ovipositions, and 21 egg clutches (35.4 ± 4.79 eggs per clutch, N = 29). Activity of males and females and the number of egg clutches were positively correlated to rainfall. Mating success of males was not associated to their body size, but it was positively associated to longer chorus tenure; clutches from large females had a higher number of eggs than clutches from small females. Oviposition occurred on average 3.76 ± 1.74 hours after we first observed the amplexus, occurring 93.1% of the time in fronds of Selaginella geniculata at an average height of 1.58 ± 0.44 m. After the oviposition, the male left the site, while the female remained between 30 and 45 min, partially covering the eggs. The reproductive behaviour of E. prosoblepon did not vary widely between a population in Costa Rica and our population in time to oviposition, and mating success of males associated to chorus tenure; however, in our study population we recorded a larger clutch size and the preference for S. geniculata fronds as oviposition substrate.     

Age structure and growth in an isolated population of Pelodytes punctatus in northern Spain

We studied the age structure and the growth of a breeding population of parsley frogs, Pelodytes punctatus, from a pond system in northern Spain using skeletochronological methods. This population lives in an upland area with marked seasonal differences characterized by long, cold winters and dry summers. We assessed, using the mark–recapture method, the annual periodicity of bone growth marks. Only one line of arrested growth is laid down per winter, showing, in general, a well-defined histological structure. Females are larger than males with 43.31 and 36.32?mm average body length, respectively. This sexual dimorphism in body length increases with age. Males and females reach sexual maturity when they are 1 year old. The oldest males were 8 years old while the females were 2 years older. Growth curves for both sexes were constructed based on body size and the number of lines of arrested growth found in bone sections. The growth rate of males declined abruptly after the first year. Females delayed reproduction and continued to grow at a high rate for 2 years longer than males, thus reaching a higher asymptotic size.     

Geographic variation in body size and sexual size dimorphism in the giant spiny frog Paa spinosa (David, 1875) (Anura: Ranoidae)

We describe the spatial pattern of variation in body size and sexual size dimorphism in the giant spiny frog, Paa spinosa (David, 1875). The study also aims to identify potential factors responsible for geographic morphological variation in the frog. The results indicate that primary production, which positively correlates with precipitation and summer temperature in China, had an important effect on body size of P. spinosa, whereas Bergmann's rule was more efficient to explain the influence of average minimum temperature in January. The species was sexually dimorphic for body size and body shape: the body size, jaw length and forelimb length of males were significantly larger than those of females. Furthermore, the degree of sexual size dimorphism varied geographically, but the relationship between the geographic variation of sexual size dimorphism and the climate was complex. Specifically, absolute sexual size dimorphism was positively correlated with the increased ambient temperature and decreased precipitation.     

Feeding ecology of the common sun skink,Eutropis multifasciata (Reptilia: Squamata: Scincidae), in the plains of central Vietnam

We studied the feeding ecology of Eutropis multifasciata in the tropical plains of central Vietnam to understand better the foraging mode, spatiotemporal and sexual variation in dietary composition, and rarefaction curves of prey-taxon richness for males and females. Stomach contents (n = 161) were collected from October 2013 to May 2014 using a nonlethal stomach-flushing technique. A total of 680 food items (624 animal items and 56 plant items) was found in 161 stomachs of skinks, representing 19 unique animal categories. We found that the diet of E. multifasciata is composed mainly of small, sedentary and clumped prey and that this skink specialises on spiders, insect larvae, snails, grasshoppers and crickets (with a combined importance index of 60%). Dietary composition, prey size and total prey volume in E. multifasciata changed between dry and rainy seasons and among regions. The total volume of food items consumed by males was larger than that of females, and the diversity and evenness index of prey categories were larger in males than in females. However, using rarefaction curves revealed that females have the higher prey-taxon richness after points between 130 and 140 prey items for frequency, and between 160 and 170 prey items for number of items, and the differences were not statistically significant. The foraging behaviour of E. multifasciata best fits a ‘widely foraging’ model.     

Reproductive features of the deep water hermit crab Sympagurus dimorphus (Anomura: Parapaguridae) inhabiting pseudoshells in the SW Atlantic Ocean

We herein provide information on reproductive aspects (the gonopore morphology of both sexes, the size of embryonic eggs and the fecundity) of the hermit crab Sympagurus dimorphus from deep waters of Argentina. Sampling was performed in different oceanographic and fishery campaigns between 2007 and 2010, at 38°01′–39°03′S, 55°–56°05′W, 85–150 m depth, in the SW Atlantic Ocean. Mean shield length (SL) of females was 9.41 ± 1.68 mm (range: 6.6–10.5 mm). Female gonopores measured 0.74 ± 0.10 mm (range: 0.45–0.90 mm), were oval in shape, and were more rounded and larger than male gonopores (0.51 ± 0.007, range: 0.4–0.63 mm). The egg volume for each of the three stages of embryonic development was 0.94 ± 0.20 mm³ for stage I, 1.14 ± 0.31 mm³ for stage II, and 2.07 ± 0.41 mm³ for stage III. Egg volume doubled from the initial to the final stage of the embryonic development. The fecundity (number of eggs) varied from 831 (6.62 mm SL) to 2246 (10 mm SL) for females carrying eggs in stages I+II, and between 158 (158 mm SL) and 1279 (9.4 mm SL) in stage III. The reproductive characteristics of the observed profile are intimately related to S. dimorphus use of a pseudoshell resource and a deep water habitat.     

Population characteristics of four deep‐water pandalid shrimps (Decapoda: Caridea) in the northern Aegean Sea (NE Mediterranean)

The population characteristics of four deep‐water pandalid shrimps (Decapoda: Caridea) were studied in the northern Aegean Sea in samples collected annually (1997–2000) in summer, through experimental trawl, at depths down to 600 m. Females were larger than males in Plesionika martia and Plesionika heterocarpus; no significant differences in size of males and females were found in Chlorotocus crassicornis and Plesionika antigai. A trend of increasing size with depth was observed, as well as a linear increase in the proportion of females with increasing size. Sex ratio was skewed towards females at all depths in P. antigai, while in P. heterocarpus and C. crassicornis males dominated the intermediate depths. Negative allometries were apparent in the carapace length–weight relationships in males of all species. Isometric relationships were found in females apart from in P. heterocarpus. The population patterns conform to relevant Mediterranean reports. However, some population differences exist that may reflect the distinct environmental conditions prevailing in the study area.     

Reproductive ecology of a Tibetan frog Nanorana parkeri (Anura: Ranidae)

Endemic to the Tibetan Plateau, Nanorana parkeri figures among the highest altitude amphibians in the world. The present work, which was conducted in an alpine marsh at 4300 m altitude, is the first report of the species’ reproductive ecology. The breeding season, as indicated by the presence of amplectant pairs and fresh eggs in ponds, lasted from early Mary to early July. The ratios of adult male to female were 1.3 in hibernation ponds and 2.3 in spawning ones. Males were smaller than females. Amplexus was typically axillary (81.7%), with a few exceptional amplexus in which a male clasped another male or object rather than gravid females. Scramble competition occurred in 6.8% of the normal amplexus located. The body sizes of amplexed couples correlated positively. Deposited eggs were attached to submerged plants solitarily (60.5%) or in small clusters (39.5%), and the scattered arrangement of individual eggs could be a strategy to ensure embryonic development in oxygen-poor environments. Clutch size averaged 189 [standard deviation (SD) = 64], and correlated positively with female body size; egg size averaged 2.18 mm (SD = 0.10), independent of female body size; both traits within a clutch were negatively related with each other even controlling for female body size. Relatively few and large eggs laid by the Tibetan frogs, compared with those by lowland aquatic-spawning anuran species, should be adaptive to the harsh high-altitude conditions. Larvae hatched from eggs after 16.4 days on average (SD = 5.8). Froglets emerged between late July and early August, but some tadpoles were present in winter. These findings may help to understand the evolution of amphibians in extreme environments and to protect these remote species.     

Natural prey of the crab spider Thomisus onustus (Araneae: Thomisidae), an extremely powerful predator of insects

The natural prey of the crab spider Thomisus onustus inhabiting Eryngium plants was studied in the Absheron Peninsula, Azerbaijan. The total percentage of specimens of T. onustus found while feeding was low (9.1%). However, solitary late instar and adult females exhibited a very high feeding percentage (29.9%). Other sex–age groups of T. onustus, including small juveniles, adult males, and females guarding egg sacs, were found feeding significantly less frequently. Investigation has shown that T. onustus is a polyphagous predator, with representatives of four arthropod orders found in its diet. The primary food of T. onustus was Diptera and Hymenoptera, which collectively accounted for 94.2% of total prey. Worker ants constituted about one‐fifth of the prey, suggesting that T. onustus is a myrmecophagic spider. The length of prey killed by T. onustus ranged between 1.25 and 16.00 mm (mean 6.21 mm) and constituted from 34.4 to 587.9% (mean 194.9%) of length of their captors. The most frequently captured were large arthropods, exceeding the size of the spiders (83.1%). Small and medium‐sized juveniles captured considerably larger prey (in terms of prey–predator length ratio) than late instar and adult females. Over half of their prey constituted arthropods more than two‐fold larger than the spiders.     

Ecological aspects of the pumpkin toadlet,Brachycephalus garbeanus Miranda-Ribeiro, 1920 (Anura: Neobatrachia: Brachycephalidae), in a highland forest of southeastern Brazil

Brachycephalus garbeanus is an aposematic toadlet, endemic to the Atlantic Forest in the mountains of the state of Rio de Janeiro, southeastern Brazil. Information regarding the ecology of species in this genus is scarce, with no information on most species, including B. garbeanus. We provide ecological information about B. garbeanus, in particular regarding microhabitat use, sexual dimorphism in body size, and feeding habits. Our study was conducted in a montane area of the Parque Estadual dos Três Picos, the largest State park in Rio de Janeiro. Most of the B. garbeanus in the study area were found on the forest floor leaf litter. Females were larger on average than males. Brachycephalus garbeanus consumed a wide array of prey, comprising exclusively invertebrates and predominantly arthropods. There were seasonal differences in the diet composition, but mites and ants were important in both wet and dry seasons.     

Reproductive biology of two species of Hyalella Smith, 1874 (Crustacea: Amphipoda: Hyalellidae) from southern Brazil

Reproduction is a critical event in the life cycle of animals, and a high amount of energy is allocated to it. The aim of this study was to characterize the reproductive biology of two recently described species of Hyalella from the north-east region of state of Rio Grande do Sul in southern Brazil. The specimens were collected during 12 months from a stream source (Hyalella georginae) and from a water reservoir (H. gauchensis), in Palmeira das Missões municipality, state of Rio Grande do Sul. Upon sampling, ovigerous females and pairs in precopulatory behaviour were separated into microtubes. In the laboratory, the cephalothorax length (CL in mm) of all specimens was measured. Male size at onset of sexual maturity was larger than that of the females, in both species. There was a correlation between the size of paired males and females: larger males carried larger females, in both Hyalella species. Precopulatory pairs were found throughout the year; however, H. georginae had a higher frequency in spring, and H. gauchensis in autumn. There was a positive correlation between the CL of ovigerous females and the number of eggs/juveniles. A reduction in the number of eggs throughout the embryonic development was observed in H. georginae. The average fecundity of H. georginae was significantly higher than H. gauchensis. The differences between the reproductive biology of these species may be related to the physical and environmental conditions at which they are exposed in their habitats.     

Reproductive patterns of Trachycephalus venulosus (Laurenti, 1768) and Scinax fuscovarius (Lutz, 1925) from the Cerrado,Central Brazil

Animal mating systems are moulded by ecological factors, mainly the temporal patterns of reproduction. We report the reproductive period, use of microhabitats, clutch and egg sizes, reproductive efforts, occurrence of sexual size dimorphism, and the relation between body size and fecundity in the gravid females of Trachycephalus venulosus and Scinax fuscovarius at Serra da Bodoquena, Central Brazil. The reproduction of both species was correlated with the rainy season. Females of T. venulosus produced more eggs and their eggs were larger than those of S. fuscovarius. The females of both species were larger and heavier than males. The reproductive effort was measured as the ratio of gonad mass in relation to body mass. Females of both species presented similar reproductive efforts, but males of S. fuscovarius invested more in gonads compared to males of T. venulosus. Trachycephalus venulosus presented significant correlation between snout–vent length versus number of mature eggs and body mass versus number of mature eggs and ovarian mass. Scinax fuscovarius showed significant correlation between body mass versus ovarian mass. Trachycephalus venulosus is an explosive breeder, whereas S. fuscovarius has prolonged reproduction. These species are able to adapt to several types of habitat, due to behavioural and physiological plasticity.     

Mating behaviour and maternal care in the tropical savanna funnel-web spider Aglaoctenus lagotis Holmberg (Araneae: Lycosidae)

Despite their abundance and diversity, Neotropical spiders have been the subject of relatively few studies of behavioural ecology. The sexual behaviour and maternal care of the spider Aglaoctenus lagotis (Lycosidae) is described here. We performed experimental manipulations to test the hypothesis that males are attracted by female cues in the web. Two predictions were tested: (a) webs used by a virgin female will attract more males than webs used by an inseminated female; (b) the main cue in the web is chemical, so webs recently used by virgin females will attract more males than those that are not recently used. Additionally, we tested the hypothesis that maternal care increases offspring survivorship. Results showed that males are attracted by recently used webs (z = 0.0015; p = 0.037; z-test) and webs of virgin females (z = 0.041; p = 0.036, z-test). Male sexual behaviour presented three different categories: court, pre-mate and mate. After the mating, the females built a cocoon that was transported adhered to the spinnerets and held by the last pair of legs. After the hatching of the eggs, the young migrated to the dorsal region of the mother's body for 5 days. During maternal care the mother eliminates a yellowish drop from its oral cavity, which is collected by the young. During the development of the young until adulthood, the offspring that have their mother present in the first stages of life have greater survival compared with those without maternal care. Our results make it possible to perform comparative analyses between a South American Lycosidae species and other species distributed worldwide.     

Observations on the tube-building behaviour of the marine amphipod Cymadusa filosa Savigny (Crustacea: Ampithoidae)

The study reports on the tube-building behaviour of the corophioidean amphipod, Cymadusa filosa Savigny on two algae, Sargassum binderi Sonder and Ulva lactuca Linnaeus, based on experimental protocols using specimens in aquaria and in petri dishes. Cymadusa filosa was observed to construct open-ended, uniform diameter cylindrical tubes using amphipod silk, to bind together faecal pellets, detritus and fronds of Sargassum binderi or Ulva lactuca. Detailed studies of tube-building behaviour were carried out in petri dishes containing Ulva lactuca, using isolated specimens (5–13 mm in size) of different sexes for a period of one and a half months. Both males and females constructed tubes, and an average of four tubes were built by adults in 15 days. Females with young in the brood pouch did not construct new tubes following juvenile release. Juveniles were observed to build tubes using detritus and faecal material only within hours of being released from the brood pouch. The tubes of juveniles were either built on the walls of their mother's tubes or on an algal mass put together by the mother. There was a highly significant positive correlation between body length and tube length in males and females. There was no significant difference in the rate of tube length increase relative to body size between males and females, between males less than or more than 10 mm, or between females of less than or more than 10 mm. Tube-sharing was also observed between males and females.     

Notes on the occurrence and biology of Xenoclarias Greenwood (Siluriformes: Clariidae) in Lake Victoria,East Africa

Summary

Xenoclarias inhabits the deeper (>50 m) waters of Lake Victoria. Specimens captured in a bottom trawl ranged in size from 10–22 cm TL (mode, 15–18 cm) and females grew to a larger size than males. Length-weight relationships between sexes were different only in the Kenya waters and resulted in significantly different KTL. Based on gonadal stages, Xenoclarias matured between 14–16 cm (age 1). Fecundity of 6 specimens (Stage VI) ranged from 744–1357 (mean 1009) and egg size from 1·45 to 1·98 mm (mean 1·79 mm).

Based on gravid and spawning females, Xenoclarias spawned prior to the rainy season (January–March) in Kenya and Uganda waters. During periods of increased reproductive activity females were consistently more numerous in samples (2:1) than males. Local meteorological and hydrological conditions may explain the apparently different spawning season in Tanzania waters of the Lake. This genus of small fish is not affected by the artisinal gillnet fishery but may be by the expansion of a bottom trawl fishery in Lake Victoria.     

Mosquitofish life history in a Mediterranean wetland

Little is known regarding the life history of Gambusia holbrooki in Europe, particularly in Italy, where it has been introduced in several wetlands since 1922. In order to increase the knowledge of its biology, we tried to clarify its life history in a Mediterranean wetland, comparing our results with those of other authors. The principal aim of this study was to describe the demographic potentialities of the studied population by modal progression analysis. Besides the curvature parameter (0.52 and 0.51 for females and males, respectively) and the asymptotic length values (39.01 and 30.45 for females and males, respectively), we observed a population divided into four age classes, for both sexes, and a longevity of 5 years, with only a limited number of mosquitofish reaching this age (due to a high mortality rate). In addition, reproduction observations were carried out for females. The most interesting aspect concerned the correlation between fecundity and body size, and the capacity of small females to absorb fertilized eggs.     

Natural history of the marsupial Thylamys macrurus (Mammalia,Didelphidae) in fragments of savannah in southwestern Brazil

The objective of this study was to furnish information on the natural history of the Neotropical marsupial Thylamys macrurus in the southern Cerrado of Brazil. A range expansion of the species was observed to the northeast of the Mato Grosso do Sul state, Brazil. Specimens were surveyed in fragments of savannah (40–600 ha) during dry and wet seasons in 2003 and 2004 with live‐trap grids and pitfall lines. With an effort of 9767 trap nights and 2200 pitfall nights, we obtained 102 captures and 49 recaptures of T. macrurus. The data analyzed (57 males and 40 females) showed that males are more abundant in the dry season and females in the wet season. Young were recorded mostly during the wet season. Thylamys macrurus was scansorial, using the floor and the understorey. Sexual dimorphism was recorded, with males being larger than females. Information on ectoparasites is supplied.     

Sexual dimorphism,reproduction and diet of the casque-headed treefrog Itapotihyla langsdorffii (Hylidae: Lophiohylini)

Itapotihyla langsdorffii is a large “casque-headed” treefrog (Hylidae: Lophiohylini) found along most of the Brazilian Atlantic Forest biome. We studied some aspects of the ecology of a population of I. langsdorffii from the Estação Biológica de Santa Lúcia, in Espírito Santo State, southeastern Brazil. Itapotihyla langsdorffii shows considerable sexual size dimorphism, with females (mean snout-vent length 103 mm) being significantly larger than males (mean snout-vent length 81 mm). This species is an explosive breeder with a generalized reproductive mode and has a mean brood size of over 6000 eggs. It feeds on few, large prey, with orthopterans being the dominant items in the diet, though even smaller frogs may occasionally be preyed upon. We discuss our data, making comparisons with other Neotropical hylids, with emphasis on other species in the Tribe Lophiohylini.     

Breeding biology of Ameerega braccata (Steindachner, 1864) (Anura: Dendrobatidae) in the Cerrado of Brazil

Reproductive aspects of Ameerega braccata, a Cerrado endemic species of Dendrobatidae, were studied in the surroundings of the type locality of the species, Chapada dos Guimarães, mid-southern Mato Grosso State, Brazil. We found that males call mainly early in the morning and in the late afternoon. During courtship, the female approaches a calling male and tactile and visual communication occurs. Males call continuously while guiding females to the oviposition site, which may be situated as far as 24 m (in a straight line) from the initial encounter site. Spawn are deposited over fallen leaves on the soil surface or in burrows. Female snout–vent length and body mass did not explain the variation in ovary mass, or the variation in the number and size of post-vitellogenic oocytes. The results reported here for A. braccata might help to understand trends in the evolution of dendrobatids in open Cerrado environments.