Comparative investigation of the late embryogenesis of Leptodora kindtii (Focke, 1844) (Crustacea: Branchiopoda), with notes on types of embryonic development and larvae in Cladocera

The embryonic development of the parthenogenetic eggs of Leptodora kindtii has been investigated by observing living embryos removed from the female brood pouch. The sequence of morphological changes was analysed, as was the time at which the activity of certain organs began. The timing of these events at 20–22°C is documented. These data were compared with similar information obtained for some representatives of Ctenopoda and Anomopoda. The sequence of appearance of rudiments of organs on the ventral side of the embryos is similar in all these groups but the timing of shedding of the embryonic membranes differs. Hatching from the inner egg membranes takes place at the late metanauplius stage in Leptodora as in Ctenopoda and Cyclestherida, while in Anomopoda this stage is embryonized. The development of Leptodora is more like that of Ctenopoda than of Anomopoda. The embryos of all the above‐mentioned groups begin to grow at approximately the same morphological stage. A new scheme for the periodization of the embryogenesis of L. kindtii is proposed, which includes four well‐separated stages. Previously, the same number of developmental stages has been reported for Ctenopoda and Anomopoda. In Leptodora, as well as in Ctenopoda, the first two of these occur within the egg membranes. Cyclestheria has at least one embryonic moult and one embryonic stage more than Leptodora and other cladocerans. Embryonic stages 3 and 4 of the parthenogenetic eggs of L. kindtii represent a peculiar type of secondary larvae developing inside the female's brood pouch. The appearance of a free‐living nauplius in L. kindtii arises from its mode of hatching from the gamogenetic egg.     

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.     

Morphology and larval development of Polydora cf. websteri (Polychaeta: Spionidae) in a tropical region of north-eastern Brazil

Polydora websteri belongs to a group of the Spionidae known as the Polydora complex, members of which are known for building tubes within the shells of mussels and for their ability to infest commercially valuable bivalves, which causes serious losses for malacoculture. P. websteri is a species subjected to increasing research due to the global scale at which these infestations occur. In this paper, we describe the larval development of P.cf. websteri associated with the oyster Crassostrea cf. brasiliana in a tropical region of north-east Brazil. The main structures of all stages of development were analysed and compared to other populations of P. websteri. Ovigerous capsules of P.cf. websteri were cultured in the laboratory and the larval stages were analysed until metamorphosis. Ovigerous capsules were present in all sampling intervals, indicating that this population exhibits continuous reproduction. Up to 21 capsules per tube were found, and the number of eggs per capsule varied from 20 to 40. All observed eggs developed into larvae. Larval development from egg to recruitment stage did not exceed 13 days. Metamorphosis occurred when larvae attained 17 chaetigers, at which stage important diagnostic characteristics were revealed, such as the spines on chaetiger 5. The developmental stages of P.cf. websteri larvae, and the morphological features found at each stage, are in accordance with what has been recorded for temperate populations. In our study, the planktonic stage was found to be of shorter duration than elsewhere, which might be associated with the higher temperatures at which larvae were cultured compared to previous studies.     

Life history of Paraselenis (Spaethiechoma) dichroa (Germar, 1824) (Coleoptera: Chrysomelidae: Cassidinae) in natural conditions of Atlantic Forest from Brazil

Cassidinae Gyllenhaal? is the second largest subfamily of Chrysomelidae (Coleoptera), which presents characteristic morphology, biology and behaviour. The current study describes the life cycle of Paraselenis(Spaetiechoma) dichroa (Germar), ?determining biological and behavioural aspects as well as the action of natural enemies on populations, when the species has maternal care. The study was conducted between February and April 2015 in the National Forest of Passa Quatro, municipality of Passa Quatro, Minas Gerais state, Brazil. Daily observations were made (morning and afternoon) to evaluate the offspring of females on Ipomoea sp. and Merremia macrocalyx (O’Donell?) (Convolvulaceae), as well as the actions of natural enemies on the young. The eggs are deposited on the midrib and abaxial surface of leaves (n = 25). Egg clusters are pedunculated, arranged in groups and devoid of any cover. On average, each female produced 27.3 ± 5.6 (n = 16) eggs, with a mean incubation period of 12.7 ± 2.9 days (n = 10 females with their young). The larvae remained grouped in the leaves throughout development, except when they fed. They retained faeces and exuviae as a stacked faecal structure on their mobile urogomphi (caudal process) like a faecal shield. The mean number of larvae per female was 12.7 ± 10.1 (n = 19) and the larval period lasted 24.9 ± 4.5 days (n = 12). Pupation occurred on the stem of the plant (n = 16). On average there were 8.1 ± 8.5 individuals for pupae progeny (n = 14). The mean duration of the pupal stage was 10.4 ± 3.3 days (n = 5). Overall, 3% of adults emerged (n = 13 individuals), with a total cycle time of 41.3 ± 8.4 days (n = 6). Adults are sexually dimorphic in the elytral shape. Females remain with the offspring throughout development. The natural enemies of immatures were Emersonella pubipennis Hansson? (Hymenoptera: Eulophidae), Tachinidae (Diptera) and Stiretrus decastigmus (Herrich-Schaeffer?) (Heteroptera: Pentatomidae), Conura sp. Spinola? (Hymenoptera: Chalcididae) and Brachymeria sp. Westwood? (Hymenoptera: Chalcididae). The information presented here on the natural history of P. dichroa are important as they may serve as a starting point to understand evolutionary questions and multispecies interactions.     

Morphology and natural history of the cryptogenic sponge associate Polydora colonia Moore, 1907 (Polychaeta: Spionidae)

The polychaete Polydora colonia is a widely distributed symbiont of sponges that has been reported as introduced into the Mediterranean Sea. Polydora colonia is re-described based on specimens associated with the sponges Microciona prolifera and Halichondria bowerbanki from New York and aspects of its reproduction and feeding biology are described for the first time. The morphology of P. colonia agrees with previous reports of this species. Females of P. colonia deposited egg capsules (14–19 eggs/capsule) in their tubes on sponges and adelphophagy was observed. Larvae appear to be competent to settle on hosts at the 13-chaetiger stage. One commensal ciliate and one parasitic copepod were found associated with P. colonia. P. colonia as an introduced species is evaluated based on current evidence. Sponge material was observed in the gut of > 50% of the worms examined but further studies are needed to evaluate whether P. colonia is selectively feeding on M. prolifera.     

Life history of Subulina octona (Brugüière) (Gastropoda: Pulmonata: Subulinidae) based on four-year laboratory observations and a comparative histological analysis of egg-retaining and ovoviviparous subulinids

In the present study, we aimed to characterize the life history of the land snail Subulina octona integrating information on life-history traits and morphology. We also compared the histology of the free-oviduct and spermoviduct of ovoviviparous and egg-retaining species of subulinids. We considered as ovoviviparous the species in which the complete embryonic development as well as egg hatching occurs inside the parent’s body and, at the end of this process, the parent releases juveniles instead of eggs. We considered as egg-retaining the species in which a great part of the embryonic development takes place inside the parent’s body and the eggs laid contain well-developed embryos. The results showed that the free-oviduct of both ovoviviparous and egg-retaining species shows a histological arrangement that confers greater strength to its walls and is probably related to egg retention. The wall of the spermoviduct is formed by pseudostratified columnar epithelium, with cell apical processes (probably cilia), and by underlying secretory cells. In gravid egg-retaining snails, the eggshells appear in close contact with the secretory cells of the spermoviduct. This fact suggests that these cells play a role in eggshell formation. The present study is the first account for histological features of S. octona, Allopeas gracile and Allopeas micra. The life history of S. octona is a combination of long lifespan, early sexual maturity, indeterminate growth and egg retention. Egg retention limits the number of young that can be produced in one reproductive event. However, the reproductive strategy adopted by S. octona, associating egg retention and K-strategism, compensates this cost of retaining eggs, because the reproductive success may be enhanced as a result of the higher survival of juveniles and the possibility of performing several reproductive events during the year.     

Hybridization of beaked redfish (Sebastes mentella) with small redfish (Sebastes viviparus) and diversification of redfish (Actinopterygii: Scorpaeniformes) in the Irminger Sea

We searched for Sebastes mentella and Sebastes viviparus hybrids in samples of redfish with external traits typical of S. mentella. The samples were collected in the Irminger Sea in 2007 (n = 131) and 2010 (n = 72). Hybrids were identified using MDH-2* locus coding malate dehydrogenase. Both samples contained hybrids (two and one individuals, respectively). The results of our investigations and previously published data show that interspecific hybridization may have a strong impact on the genetic structure of S. mentella in the Irminger Sea, presumably being one of the main reasons for the differentiation of allele frequencies of some genes between samples collected at different depths. This should be taken into consideration in studies of Irminger Sea redfish.     

Pre-ovipositional and ovipositional behaviour of Lasioseius ometes (Oudemans) and Hypoaspis kargi Costa (Acari: Dermanyssiae: Ascidae,Laelapidae) with notes on egg protection strategies in Mesostigmata

Egg deposition by the soil mites Lasioseius ometes (Oudemans, 1903) and Hypoaspis kargi Costa, 1968 was observed using continuous video-monitoring. The process in both species was found to consist of four distinct phases. In Phase 1, both species engage in pre-ovipositional activity prior to the egg being extruded from the genital opening. In L. ometes, the female often selects a substrate depression for egg laying and examines the depression carefully with the gnathosoma and legs I before oviposition. In H. kargi, egg deposition sites are chosen without regard for substrate depressions. Phase 1 lasted approximately 3 minutes for both species. Phase 2 involved egg extrusion and holding of the egg beneath the gnathosoma. Phase 2 lasted approximately 20 times longer in L. ometes (5 minutes) than in H. kargi. Alteration of the egg surface in the form of thorn-like outgrowths was recorded in L. ometes. Egg deposition occurs in Phase 3, and in L. ometes the egg is generally placed at the deposition site using the chelicerae. Hypoaspis kargi also uses the chelicerae for egg manipulation, but also adjusts orientation of the egg with legs I. The sticky nature of egg surface in H. kargi may provide a means for the female to effectively cover the exposed egg with a protective layer of soil particles. Egg deposition in both species occurred in less than 90 seconds. Phase 4 involves egg covering, but behaviour of the female during this last phase differs markedly between the two species. In L. ometes, the female tends to remain close to the egg, whereas in H. kargi the female moves away from the egg to search for substrate particles appropriate for its covering. The average time for Phase 4 in H. kargi was approximately four times longer (80+ minutes) than in L. ometes.     

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.     

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.     

Camera traps capture images of predators of Caiman crocodilus yacare eggs (Reptilia: Crocodylia) in Brazil’s Pantanal wetlands

Camera traps were set up in forest nests in 2009, 2010 and 2012 to capture images of possible predators eating eggs of the Pantanal caiman, Caiman crocodilus yacare. We monitored 57 caiman nests; 42 nests were opened and the eggs were counted (mean = 25 eggs/nest, SD = 4.3). Females were present and captured at 38 of those nests. The remaining 15 nests were used as controls, and we did not capture the females or open the egg cavities of these nests. Most of the nests had the eggs eaten by predators, in both the disturbed group (38 nests) and the control group (13 nests). The main predators were carnivorous mammals, such as crab-eating foxes (Cerdocyon thous), coatis (Nasua nasua) and tayras (Eira barbara), although feral pigs (Sus scrofa) and armadillos (Dasypus novemcinctus) were also photographed eating caiman eggs. The lizard Salvator merianae was photographed eating eggs of two nests.     

Characterisation of burrow architecture under natural conditions in the sand-dwelling wolf spider Allocosa brasiliensis

Allocosa brasiliensis (Petrunkevitch, 1910) is a wolf spider that constructs silk-lined burrows along the coastal sand dunes of Argentina, Brazil and Uruguay. This species shows a reversal in typical sex roles and sexual size dimorphism expected for spiders. Females are the smaller and mobile sex, which initiates courtship at the male burrow entrance. Mating occurs in the male burrow, and when it ends, the male leaves and the female stays inside. Females prefer to mate with those males showing longest burrows, so burrow dimensions would be under strong sexual selection pressures. Previous studies in the laboratory indicated that male burrows are longer than those of virgin females, which were described as simple silk capsules. Preliminary observations suggested that juvenile burrows presented differences from those of adults; however, detailed observations of A. brasilienisis burrow characteristics at the field were lacking. The aim of this study was to characterise the burrows of adults and juveniles of A. brasiliensis under natural conditions. We recorded the dimensions of burrows inhabited by males, females and juveniles (n = 30 for each category) and created beeswax moulds that reflected burrow shape. Juveniles inhabited tubular burrows with two branches and two openings; on the contrary, adults were found in tubular burrows with a single entry. Males and females inhabited burrows of similar length and width, but those of juveniles were shorter and narrower. We discuss the results and their possible functional explanations according to the selective pressures expected for each developmental stage and sex.     

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.     

Mating behaviour,nympho-imaginal development and description of a new Mesabolivar species (Araneae: Pholcidae) from the Brazilian dry forest

A new species of Mesabolivar is described from Brazilian forests: Mesabolivar delclaroi. The mating behaviour, postembryonic development, number of egg sacs and eggs, birth rate, number of instars, developmental time until adulthood, sex ratio and size of cephalothorax (per instar) were recorded. The sexual behaviour was described and categorized into four steps: courtship, pre-copulation, copulation and post-copulation. After hatching, individuals presented five instars until maturity. The mean number of eggs (42 ± 16.6) and live births (31.5 ± 3.4) of the first egg sac were significantly greater than that of a second one (23.8 ± 3.8, and 19.25 ± 3.9, respectively). The developmental time from birth to adulthood (130.8 ± 9.6 days) did not differ significantly between egg sacs produced (128.61 ± 11.1). The size of the cephalothorax did not differ among adults or between sexes. The sex ratio revealed a shift in favour of females (4: 3).     

Breeding biology of the Pale-bellied Tyrant-manakin Neopelma pallescens (Aves: Pipridae) in south-eastern Brazil

The Pale-bellied Tyrant-manakin (Neopelma pallescens) inhabits semi-deciduous and riparian forests in central-north South America. Contrary to most manakins, there is no evident sexual dichromatism in the species and little is known about its breeding biology. We studied the breeding biology of a colour-banded population of the species from August to December 2016 and from August to October 2017 in the Campus Florestal of the Universidade Federal de Viçosa, south-eastern Brazil. The breeding season extended from early September to late November. The species is promiscuous, with males exhibiting simple courtship displays (exploded leks) in individual arenas. The nest (n = 13) is a cup attached by its top lip between forked branches and is very simple, with a structural layer made with dry grass stems and heads, attached to the branch with spider silk. The outer and lining layers are absent. The mean clutch size was 1.8 eggs (n = 11), which are oval and pale coloured, covered with spots of different shades of brown, often concentrated in the larger pole. Mean egg length and width (± SD) were 21.0 ± 0.9 × 15.8 ± 0.7 mm (n = 14) and the mean weight was 2.8 ± 0.4 g (n = 10). The incubation period could not be estimated, but the nestling period was 15 days (n = 2). The simple percentage of successful nests was 15.4%, with 76.9% of the nests depredated and 7.7% abandoned. This is the first detailed study about the breeding biology of any Neopelma species, providing relevant data for the study of the evolution of life history strategies not only for the genus, but for the whole family Pipridae.