Natural history and behaviour of the primitively eusocial wasp Ropalidia marginata (Hymenoptera: Vespidae): a comparison of the two sexes

We report the natural history and behaviour of the primitively eusocial wasp Ropalidia marginata with a special reference to the males. We found that just as nests of this species are found throughout the year, so are the males. Females spend all their life in their nests but males stay in their natal nests only for 1–12 days and leave to lead a nomadic life. Males maintained in the laboratory can live for up to 140 days. Like all eusocial hymenopteran males, R. marginata males also do not perform any colony maintenance activities. We found that males did not forage or feed larvae. Compared with females, males showed fewer dominance and subordinate behaviours and being solicited behaviour and more feeding self and soliciting behaviours. By comparing males with young females, we found similar differences, except that the males showed similar rates of feeding self and higher rates of subordinate behaviour.     

Age,body size and growth pattern of Argenteohyla siemersi pederseni (Anura: Hylidae) in northeastern Argentina

In this study we analysed the body size, age structure, age at maturity, longevity and growth pattern of Argenteohyla siemersi pederseni in north-eastern Argentina using skeletochronological methods. Body size was sexually dimorphic; females were significantly larger and heavier than males, regardless of age. As A. s. pederseni is an explosive breeder with only one reproductive episode per year, we assumed that each Line of Arrested Growth (LAG) observed was equivalent to one period of decreasing growth, LAGs reflecting a direct estimation of individual age. The minimum number of LAGs counted was two for males and three for females, but there was no sexual difference in longevity. The von Bertalanffy's growth coefficients (K) were higher in males than in females for both size and body mass. Females had a lower growth rate than males, took longer to reach the minimum maturation size, and were older and larger at reproduction.     

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.     

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%).     

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.     

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.     

LX.—Copepoda and Cladocera of the Cuillin Hills of the Isle of Skye

Summary

The life history of the African grasshopper Ornithacris turbida (Walker) was studied under controlled laboratory conditions. No phase variation was observed between isolated and crowded stock in respect of colour, morphometrics, weight of hatchlings or fledglings. All the females reared in isolation Had seven nymphal instars but in the case of the isolated males the majority had six but some had seven nymphal instars. This variation was also observed in the crowded stock for both males and females.

In isolation the mean nymphal life of 15 females was 78·7 ± 3·2 days, the mean for nine males having six instars was 59·9 ± 3·2 days and for five males having seven instars the mean nymphal life was 74·6 ± 3·8 days. Overall the nymphal life for the insects reared in crowds was slightly shorter, but no attempt was made to separate the insects having six or seven instars.

The stripes in the compound eye correlated with the number of nymphal instars. Colour changes in the compound eye coincided with overall body colour changes and maturation.

The mean maturation period of females reared in isolation was 101 days, varying from 72 to 158 days. The mean maturation period of the crowded females, estimated by the collection of the first egg-pod, was 73 days with a range of 62 to 84 days; when estimated by the collection of egg-pods averaging one per female it varied with the cage from 91 to 114 days. This suggests that maturation in the crowded females was quicker.

The isolated females lived longer than ones reared in crowded conditions, and laid more egg-pods. There was, however, no difference in the number of eggs per pod or their hatchability between crowded and isolated stock. In both cases 76% of the total number of eggs hatched. Hence overall the isolated females had a greater fecundity than those reared in crowds.

The average weight of a single hopper from isolated parents was 15·5 mg and that from crowded parents was 14·0 mg.     

Breeding behaviour and mating success of Phyllomedusa rohdei (Anura,Hylidae) in south‐eastern Brazil

Observations on the courtship behaviour, mating behaviour and mating success of a leaf‐frog, Phyllomedusa rohdei, population were conducted in a temporary flooded site of the Atlantic Forest, south‐eastern Brazil. We did not find any influence of size and body weight on male mating success across three scales: seasonal, nightly chorus and local groups (males found within 1?m of a mated pair). In addition, no evidence was found that female Phyllomedusa rohdei exhibit overt mate choice. The formation of mated pairs in P. rohdei occurred because males moved toward the females, rather than reverse. The only variable that was significantly related to male mating success was the number of nights of participation in chorus activity. Besides calling tactics, males showed active searching behaviour. There was no evidence of size‐ and mass‐assortative mating, and a high percentage of fertilization at all size and mass ratios of males and females was observed. Clutches in this species are produced in the same manner found in others members of Phyllomedusa; a purse‐like nest is made over water by folding a leaf around the egg mass (embryos and fluid‐filled capsules). Finally, we supply a list of several studies that examined the relationship between size or mass ratios of males and females in amplexus and its influence on fertilization rate, and show that size‐assortative mating in anurans is inconsistent (present in some species but not in other).     

Population structure and breeding season of the hermit crab Diogenes brevirostris Stimpson, 1858 (Decapoda,Anomura, Diogenidae) from southern Mozambique

In this study the population dynamics of the diogenid hermit crab Diogenes brevirostris is evaluated focusing on size structure, sex ratio and breeding season. Crabs were randomly taken on a monthly basis from January to December 2003 at Costa do Sol, Maputo Bay, southern Mozambique. A total of 622 crabs was obtained of which 290 were males (46.6%), 170 were non‐ovigerous females (27.3%) and 162 were ovigerous females (26.1%). The overall size frequency distribution was unimodal for males, non‐ovigerous females and ovigerous females. The overall sex ratio (1:1.15) differed from the expected 1:1 ratio. Sexual dimorphism was evidenced by the larger size attained by males in relation to both ovigerous and non‐ovigerous females. Breeding took place year‐round with three peaks of spawning (March, August and December). Despite the high reproductive activity, young recruits were scarce in the population. The present results suggest that the study area is suitable for reproduction and growth whereas recruitment may take place in different areas from that occupied by the adults.     

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.     

Population dynamics,age structure and sex ratio of the bromeliad-dwelling jumping spider,Psecas chapoda (Salticidae)

In this study, the population fluctuations, phenology and sex ratio of the bromeliad-dwelling jumping spider Psecas chapoda were investigated in an area of semi-deciduous forest in south-eastern Brazil. Psecas chapoda occurred and reproduced on Bromelia balansae (Bromeliaceae) throughout the year. The number of egg sacs increased at the beginning of the rainy season (September to December), but the population size and phenology were stable over time and correlated weakly with rainfall and temperature. The principal factor affecting the dynamics of P. chapoda was the blooming of B. balansae, which expelled spiders because of the drastic change in plant architecture. Male spiders were more frequent than females during the juvenile phase, whereas females were more frequent than males during the subadult and adult phases, suggesting a sex ratio that favoured males. The biotic and abiotic factors that influence the population dynamics and sex-dependent vulnerability determination are discussed.     

Life history of the spider Selenops occultus Mello‐Leitão (Araneae,Selenopidae) from Brazil with notes on the natural history of the genus

Selenopids are extremely fast‐moving, dorsoventrally flattened spiders and are among the most secretive of animals. However, they can be locally abundant, providing an opportunity to examine their life and natural histories. Here we report life history data from Selenops occultus which were studied and collected monthly for over a year at an experimental farm of São Paulo State University in Botucatu, Brazil. We compare these data with what we have found in other Selenops species in the Caribbean region. Overall, S. occultus showed considerable seasonality. Males were most common in January and March, whereas females were more common in June and November. Significant differences between the numbers of males collected during the wet and dry seasons indicate that mating may be limited to the wet season. The Caribbean species share similar natural histories to S. occultus, such as little conflict in small areas and overlapping generations throughout the year.     

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.     

The reproductive ecology of the Tahoe sucker, Catostomus tahoensis, in Pyramid Lake, Nevada

The Tahoe sucker spawns in Pyramid Lake from April to August at lake temperatures of 11.7 to 22.7 C. The spawning population is comprised of a large lake spawning group and a numerically smaller river running group. The river running group is smaller in length and was not considered during this study. The sex ratio of sampled suckers significantly favored the females. This is the result of the longer life of females and greater mortality of males during spawning.   Pyramid Lake Tahoe suckers reach sexual maturity at two to three years of age; however, those in Lake Tahoe do not mature until four or five years of age. The size at sexual maturity is different in both populations, which suggests that size or rate of growth rather than age determines sexual maturity.   The fecundity of Tahoe suckers is positively correlated with fork length, weight, and age. Additional analysis showed that a better correlation occurred between fish size (either length or net weight) and total ovary weight. We believe that fish size is primarily correlated with total reproductive tissue produced and secondarily with fecundity. A comparison of the Pyramid Lake population and the Lake Tahoe population demonstrated that size, not age, is the most important determinant of Tahoe sucker fecundity.     

Dietary variation and overlap in D’Orbigny’s slider turtles Trachemys dorbigni (Duméril and Bibron 1835) (Testudines: Emydidae)

Although D’Orbigny’s slider (Trachemys dorbigni) is the most abundant freshwater chelonian species in southern Brazil, little is known about its feeding habits. Our goal was therefore to evaluate this species’ dietary composition and niche variation there. For this, we collected road-killed animals (n = 73) on a federal highway (BR 392) between 2002 and 2003, and analysed their gut contents. We identified 26 different dietary items, and our results indicated that D’Orbigny’s slider is omnivorous in this area. Total food volume, as well as the degree of herbivory and carnivory, were similar between males and females. However dietary composition of plants was different: although both males and females fed on underwater plant matter, only females consumed surface macrophytes. This finding suggested differential microhabitat usage between males and females throughout the swamps.     

Relative growth and sexual dimorphism of the South Atlantic hermit crab Loxopagurus loxochelis (Anomura,Diogenidae) from Ubatuba,Brazil

Some morphometric relationships and biometric aspects were studied in the hermit crab Loxopagurus loxochelis (Moreira, 1901) with the purpose of describing its relative growth and finding the size where sexual maturity is reached. Specimens were collected monthly from September 1995 to August 1997 in the Ubatuba region using double-rig trawl nets. A total of 1084 specimens (625 males and 459 females) was analysed. In this species, sexual dimorphism is particularly evident in chela dimensions. Differences between males and females were found in the left propodus length versus cephalothoracic shield length (CSL) and wet weight (WW) versus CSL relationships. Males showed a high positive allometry in chela growth, while females were close to isometry/negative allometry. The size at which a clear differentiation occurred in the growth of the propodus length and in the increase in weight of males and females was between 4.5 and 6.0mm CSL, suggesting that size at which sexual maturity is reached.     

Not every drought is bad: quantifying reproductive effort in the harlequin frog Atelopus laetissimus (Anura: Bufonidae)

Atelopus laetissimus is an endemic and threatened harlequin frog from the high mountain forests of Sierra Nevada de Santa Marta, Colombia. Knowledge of its reproductive biology is essential for understanding the intraspecific interactions that can help the conservation of Atelopus species. We quantified the energy, measured in body weight, invested by males and females of A. laetissimus for reproduction, and how this energetic investment is related to the survival of individuals and rainfall conditions in habitats during two years (2014 and 2015). Our results show plasticity in terms of reproductive phenology linked to rainfall with short- and long-duration breeding strategies. The first year of this study, 2014, had a precipitation level in accordance with the annual averages at the area. During this time frogs exhibit a short breeding period. Contrary to 2014, 2015 was a year with little precipitation, below the annual averages, which probably facilitated the females’ quick spawning in the creeks and a consequent reduction in the duration of amplexus and low breeding efforts by males. This, in turn, was related to a long breeding period that favors the survival and reproduction of males during the entire year. In 2014 we found a decrease of 25% to 30% body weight of potentially reproductive males, which may be attributed to a prolonged duration of amplectant events.     

Diurnal colour change in a sexually dimorphic trait in the Andean lizard Anolis heterodermus (Squamata: Dactyloidae)

Sexual dimorphism in body size, shape and colour is widespread in lizards as well as in other taxa. In the context of sexual selection, these sex differences are commonly manifested as exaggerated male traits, which are selected by females to assess the quality of males. However, differences in sex by environment interactions can also lead to sexual dimorphism. The genus of Anolis lizards is particularly well known for sharp sexual dimorphism in dewlap colour and size; however, this is not the case in all anole species. Using digital image analyses, I assessed the existence of sexual differences in the diurnal change in colour and size of a conspicuous patch on the tail of the lizard Anolis heterodermus Duméril 1851. Results showed that the tail patch of both males and females changed in colour, but not size, from red to blue throughout the day in a similar fashion. This process took almost half a day to complete and occurred in the absence of conspecifics, suggesting that the change itself may not have an active role in social communication. However, the colour patches of males were consistently larger. The cause of the substantial variation in colour and size of the tail patch of A. heterodermus is still unknown and deserves more research. This study highlights the importance of continuous wildlife observations to identify life history traits that may be important in animal behaviour but are challenging to observe in nature.     

A new species of Crepidula (Mollusca: Mesogastropoda: Calyptraeidae) from Chile: additional characters for the identification of eastern Pacific planar Crepidula group

A new species of Crepidula is described. It was collected together with Pagurus edwardsii Dana and Pagurus perlatus H. Milne Edwards, inhabiting the inside of empty shells of Tegula euryomphala Jones and other gastropods. The shell is low convex-oval in juveniles, low convex-oblong in males and concave-oblong elongated in females. In the adult phases the apex projects slightly at the posterior border. The sinusoidal septum is ‘V’ shaped at its centre, with a smooth sulcus in the left quarter. The osphradium has 2–13 digitiform leaflets according to phases of the life cycle. The characteristically thin, external-lateral teeth of the taenioglossate radula possess a row of denticles. In addition, evidence is given that: (1) males have a lanceolate penis with a spermatic tube; (2) the intracapsular-embryonic development starting with many embryos, occurs with a decrease at the larvae-protoconch stage, each one with an adhered-vitelline mass, and culminates with a few prehatching juveniles of 1 mm size. In the expression of the consecutive-protandric hermaphroditic sexuality, the male phase is truly separated from the female phase by a transition period at the population level. The shell and radular morphology, intracapsular development and ecological antecedents allow the proposal of Crepidula coquimbensis as a new species, and suggest a future taxonomic revision of the group based, moreover, on osphradium structure and new characters of the reproductive system, such as penis morphology.