Reproductive strategies of two sympatric species of Hyalella Smith, 1874 (Amphipoda,Dogielinotidae) in laboratory conditions

This study was performed in order to test theoretical predictions that sympatric species might show different reproductive strategies to facilitate their coexistence. The duration of precopulatory mate‐guarding behaviour, body size of ovigerous females, embryonic and postembryonic development time, fecundity, and viability of the sympatric amphipod species Hyalella pleoacuta and H. castroi were investigated under laboratory conditions (19±1°C and 12 h light/dark photoperiod). Specimens were collected with nets in autumn and spring 2004, and summer and winter 2005 in the Vale das Trutas, São José dos Ausentes County, southern Brazil, and transported to the laboratory. Both species of Hyalella showed similar reproductive strategies, especially in respect to the duration of the precopula, duration of the embryonic period, and fecundity. However, these species differed in body size of ovigerous females, duration of the postembryonic period, viability, and body size of juveniles that remained in the marsupium and those released by females. These differences in the reproductive traits of H. pleoacuta and H. castroi may facilitate their coexistence in nature.     

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.     

Aspects of the life history and reproductive biology of the introduced terrestrial amphipod Arcitalitrus dorrieni (Hunt) at two sites in Co. Galway,Ireland

The reproductive biology of Arcitalitrus dorrieni (Hunt) was investigated over a period of 25 months at a deciduous and a coniferous forest site at Kylemore, Co. Galway, Ireland. The species has an annual, univoltine reproductive cycle with ovigerous females found throughout the year. Recruitment of juveniles begins in May–June with a peak of reproductive activity in August–September. The populations at each site show a bimodal size-distribution for most of the year, with a unimodal distribution in March, April and May. Mortality occurs exponentially, and the life-span is 20–22 months. Mean fecundity was 5·65 eggs per female and was dependent on female size, egg size and brood stage. Brood mortality was 37·5% at Addergoole and 29·8% at Tullywee Bridge.     

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.     

Winter-active wolf spiders (Araneae: Lycosidae) in thermal habitats from western Romania

Shores of channels with thermal water provide an adequate microclimate for maintaining wolf spiders in activity during winter. Of the spiders collected after the winter survey of 22 thermal habitats from western Romania, 93.02% were juveniles and subadults, while the remaining individuals belonged to the following seven species: Arctosa leopardus, Pardosa amentata, Pardosa proxima, Pirata piraticus, Piratula latitans, Trochosa robusta and Trochosa ruricola. The reproductive period of some species is altered under the influence of neighbouring hot waters, as revealed by the capture of females with egg sacs and spiderlings, during winter.     

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.     

Reproductive biology of Limnoria chilensis: another boring peracarid species with extended parental care

Several boring peracarid species engage in extended parental care with parents tolerating small juveniles in their burrows, but only anecdotal observations have been reported from boring isopods of the genus Limnoria. The isopod Limnoria chilensis Menzies is frequently found in holdfasts of the macroalgae Macrocystis pyrifera (L.) C. Agardh and Durvillea antarctica (Chamisso) Hariot. In the present study, holdfasts of D. antarctica that harboured L. chilensis were carefully dissected in order to examine the association pattern of reproductive females and small juveniles. In most infested holdfasts, L. chilensis reached very high densities of 43.7 ± 3.9 (mean ± SE) individuals cm^?2 (range: 0–90 individuals cm^?2). The overall sex ratio (females:males) was close to unity (1.2). Male size varied between 1.5 and 2.6 mm body length (BL) and female size between 1.5 and 3.6mm BL. The percentage of reproductive females was low (19.7% of all females), and only the largest females (>2.6 mm BL) were reproductive. Embryo numbers ranged between six and 19 per female and a significant correlation between female BL and the number of embryos was found. Several females were found with small juveniles (0.8–1.2 mm BL) in the terminal end of their burrows. On several occasions, aggregations of similar-sized juveniles (1.0–1.5 mm BL) in their own burrows were found near a female burrow, indicating that these juveniles initiated their first individual burrows from within the maternal burrows. Some females with small juveniles in the terminal end of their burrows were either accompanied by males or they were ovigerous, indicating that they may have been in the process of producing a second brood. The fact that juveniles build their first burrows in the protection of female burrows suggests that such small juveniles have not yet developed full boring capacity. Extended parental care in this (and other boring) peracarid species represents a mechanism facilitating high juvenile survival rates. Given the highly local recruitment, it is suggested that the reproductive biology of this isopod has strong implications for Its population biology.     

Reproductive behaviour of the glass frog Hyalinobatrachium cappellei (Anura: Centrolenidae) in the Southern Amazon

Frog species of the Centrolenidae family exhibit a high variation in reproductive behaviours. Herein we describe the reproductive, ecological, acoustic and behavioural features of Hyalinobatrachium cappellei in Southern Amazon. Two hypotheses were also evaluated: (1) are ecological characteristics of the reproductive site related to male size and quantity of eggs and clutches? And (2) do males with one or more existing clutches at reproductive sites accumulate more new clutches than those males initially without them? This study was conducted at two streams, with sampling at 1 km each in Southern Amazon. Species reproduction occurred during the wet season and was considered prolonged breeding. Although male vocalization occurred on both the upper and underside of leaves, clutches were most often deposited on the underside of leaves. Males emitted a courtship call upon female approach. The process of female approach until oviposition lasted approximately eight hours. After oviposition, females left the breeding site while males remained near the clutch, covering it with the belly in ventral brooding behaviour. Thus, egg attendance is reported for the first time for this species. No intraspecific or interspecific aggressive behaviour was recorded. There was no relationship between habitat characteristics of the reproductive sites and male size, number of eggs and clutches. However, after 10 days of monitoring, we found evidences that parental males had a higher number of clutches than those males initially without clutches. Similar to other glass frog species, the behavioural characteristics of H. cappellei make this species an excellent model to use in evaluating the cost-effectiveness of parental care and the importance of egg attendance for offspring survival. Therefore, these data contribute towards a better understanding of the complex phylogenetic and biogeographic relationships between centrolenid lineages.     

Biometry of brooding in seven species of amphipod (Crustacea) from the Clyde Sea area

Brood size was found to be correlated linearly with female body length in all species studied, except Ampelisca macrocephala, which is usually a single brooded species. Of the six multi-brooded species, Lembos websteri, Stegocephaloides christianiensis, Echinogammarus pirloti and Gammaropsis nitida produced small numbers of large eggs in the winter and large numbers of small eggs in the summer. In Bathyporeia pilosa larger numbers of smaller eggs were produced by the overwintering generation. In Corophium bonnellii, both maximum and minimum brood sizes were produced by the summer generation. The largest broods relative to female body size were produced by the smaller species. In L. websteri, C. bonnellii and B. pilosa mean female size was smaller in the summer than the winter generation.     

Activity and reproduction in Megalobulimus paranaguensis (Gastropoda,Eupulmonata): implications for conservation in captivity for a South American land snail

ABSTRACT

In South America, Megalobulimus includes a number of threatened species, as well the largest land snails on the continent. The activity patterns and reproductive aspects of this group have not been documented. This work describes the daily and seasonal activity patterns and reproduction of M. paranaguensis. We maintained specimens in the laboratory for one year, and we quantified their behaviour for one hour at four different times of the day (0 h, 6 h, 12 h and 18 h) during three days in four months (August, September, April and May). The number of postures, hatching rate, time of hatching since oviposition and mortality rate among juveniles for each month were also quantified. Megalobulimus paranaguensis was more active in August, and had a egg laying peak one month after. Fifty-one eggs were laid by 12 captive individuals throughout the year, with a mean value of 4.25 eggs per individual. The hatching rate was 80.39%, and the time of hatching since oviposition was 56.7 ± 4.3 days. In two eggs, we observed the presence of twins. The mortality rate among juveniles was low (9.30%) indicating that rearing land snails in captivity has the potential to be an important and viable tool for the management and conservation of these organisms.     

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.     

Seasonal abundance and life cycle of Archaeomysis articulata (Crustacea: Mysidacea) on a sandy beach of western Hokkaido,Japan

Abundance and life cycle of the sandy beach mysid Archaeomysis articulata Hanamura were investigated based on seasonal collections over 2 years in the surf-swept intertidal zone of an open sandy beach in Ishikari Bay, western Hokkaido, Japan. The number of mysids in the intertidal zone increased from winter to spring, reaching its maximum in summer to autumn (average >2500 ind. m^-2), and decreased considerably towards the end of the year. The abundance was maintained at a minimal level (<200 ind. m^-2) throughout the winter. The breeding season was March to November, during which the liberation of young was most intensive from late April to mid-October. Three alternate generations, including overwintering, spring and summer generations, were suggested from field observations. Archaeomysis articulata is primarily iteroparous; only a restricted number of breeding females could produce more than two broods. The life span was estimated to be 7–9 months for the overwintering generation and 2.5–3.5 months for the spring–summer generations. The sex ratio fluctuated at samplings, with a tendency toward female dominance (overall mean=54%). The number of embryos carried by a single female ranged from 16 to 94, tending to increase with increasing size of females. The size of egg-like embryos varied seasonally from 0.45 to 0.54mm, being largest in spring and smallest in summer, with no correlation to the length of females; water temperature is considered an important factor in regulating the size of eggs. The embryonic development time was estimated to be 1.5 months for the spring generation (water temperature 5–10°C), and much shorter than this for the summer and overwintering generations. The mortality rate during embryonic development was estimated to be 7–18%.     

Extended parental care in two endobenthic amphipods

Extended parental care is described for two endobenthic amphipods which inhabit the estuarine soft-bottoms along the Gulf of Maine. The juveniles of both amphipod species, Leptocheirus pinguis and Casco bigelowi, remain in the burrow of their mother after they hatch from the brood pouch. Several consecutive clutches of L. pinguis can inhabit the female's burrow simultaneously, but in C. bigelowi there is always only one clutch of juveniles in the burrow of the female. Larger juveniles of L. pinguis start building their own small tubes at the bottom of the female's burrow. Casco bigelowi females increase the size of their burrows during the time when the juveniles grow. The juveniles of both species leave the female's burrow at about half adult size. The major tasks of female L. pinguis and C. bigelowi during the time of extended parental care is to irrigate and maintain the deep burrow. It is hypothesized that extended parental care in L. pinguis, C. bigelowi and other tube/burrow-living peracarids is a mechanism to protect small offspring from epibenthic predation.     

Interspecific differences in early life‐history traits in crested newts (Triturus cristatus superspecies,Caudata, Salamandridae) from the Balkan Peninsula

We studied intraspecific and interspecific variations of early life‐history traits for four crested newt species with different habitat preferences. Although we found considerable variation in size and growth rate between offspring of conspecific females, the species effect appeared to be much more pronounced. The crested newt species we examined differed in egg size, size of larvae at hatching and growth rate. Triturus dobrogicus appeared to be the outlier species among these species, and showed (1) the smallest egg size, (2) the smallest larval size at hatching and (3) the longest larval period, resulting in the largest metamorphosed juveniles.     

Postembryonic development and population parameters of Alpaida veniliae (Araneae,Araneidae), reared in the laboratory

We studied the postembryonic development from hatching to the adult stage and determined population parameters of Alpaida veniliae. It is one of the most abundant species of the orb-weaving guild of the spider community of soybean crops in Buenos Aires province, Argentina. The first three instars occurred inside the egg sac, and instar IV (spiderlings) started the dispersion from it. The female of Alpaida veniliae achieved greater adult size and adult longevity than the male. Mean fecundity, mean number of egg sacs per female, mean number of eggs per egg sac, as well as the net reproductive rate, the intrinsic rate of increase (r), the generation time (T), and the reproductive values (V _x) of three cohorts were determined under laboratory conditions, indicating a high capacity for growth. Their biological and ecological attributes indicate the importance of conservation of this predator as a natural enemy of soybean crop pests.     

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.     

An overview of female reproductive traits in South American Mabuya (Squamata,Scincidae), with emphasis on brood size and its correlates

The viviparous New World Mabuya (Reptilia, Scincidae) are characterized by a peculiar suite of reproductive traits associated with an extreme degree of matrotrophy and a specialized placenta. We gathered information on female reproductive traits of South American Mabuya based on a compilation of literature data plus original information on two species (Mabuya dorsivittata and Mabuya macrorhyncha). Considering brood size, we identified one “large-brooded” group (brood sizes up to eight to ten) and one “small-brooded” group (brood sizes up to four to six). Brood size tended to be positively correlated with female body size among species, although the correlation is not as strong as it is within species. There were some general trends for the reproductive ecology of New World Mabuya, such as early sexual maturation, brood sizes of usually four to six young, and parturition occurring around the dry–wet season transition.     

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 biology of Scinax fuscomarginatus (Anura,Hylidae) in south‐eastern Brazil

The present study describes the reproductive biology of Scinax fuscomarginatus in a remnant of Cerrado in south‐eastern Brazil. Observations were made between September 2002 and March 2004 at Estação Ecológica de Itirapina, State of São Paulo, south‐eastern Brazil. Breeding activities occurred in lentic and temporary bodies of water during the rainy season. Scinax fuscomarginatus exhibited a prolonged breeding pattern and a lek mating system. Males were smaller than females and defended individual calling areas through acoustic and physical interactions. Resident males consistently won encounters, but did not differ in size or mass from intruder males. Satellite behaviour was observed, but no female or amplected pair interception was registered. Scinax fuscomarginatus exhibited low operational sex ratios and the general reproductive mode in which eggs are laid in the water and tadpoles are aquatic. Amplexus was axillary and the eggs were deposited at the bottom of temporary ponds. Details on oocytes, egg masses, and eggs are included.