Egg Size Research Articles

Evo‐devo in the ophiuroid family Ophiocomidae

AbstractThe Ophiuroidea, the most diverse echinoderm class, exhibits an array of life history patterns and larval forms, the evolution of which is poorly understood. With a robust phylogeny available for the major family, the Ophiocomidae, we undertook an assessment of the evolution of development in these ophiuroids. We spawned 15 species and documented larval development in 14 of these. In total, data on egg size or larval development were available for 27 species across the four recognized genera (Breviturma, Ophiocoma, Ophiocomella, and Ophiomastix). Ophiocomids have a bimodal egg size distribution. Species with small eggs (x̄ = 82 μm diameter, range 55–100 μm diameter) and large eggs (x̄ = 424 μm diameter, range 335–550 μm diameter) have planktotrophic ophioplutei and lecithotrophic vitellariae, respectively. The advanced ophiopluteus transforms into an armless vitellaria prior to metamorphosis through resorption of the larval arms and rearrangement of the ciliary tracts into series of transverse bands. Thus, the Type II pattern of development (which includes both the ophiopluteus and vitellaria) may be characteristic of the Ophiocomidae. This is not seen in other ophiuroid families. Evolution of nonfeeding (lecithotrophic) development through a vitellaria larva appears to have occurred only once in this family, in the genus Ophiomastix. Several traits appear to be specific to some species or genera, including an ornate fertilization envelope (Ophiocoma species), the presence of an early barrel‐shaped larva (Breviturma species), and the presence of vibratile lobes in advanced ophioplutei (Breviturma, Ophiocomella). In species with lecithotrophic development, the vitellaria is distinct, with prominent ciliated lobes around the developing juvenile rudiment. Larval form may assist with identification of ophiocomid larvae in plankton samples.

Filling latitudinal gaps in Tachycineta swallows: reproductive strategies in a South American species

ABSTRACT Chilean swallows (Tachycineta leucopyga) are the southernmost swallows in the Tachycineta genus, breeding from central Chile to southern Chile and Argentina. Studies focused on a population breeding at 54°S in Tierra del Fuego, revealed differences in life-history traits compared to their Northern Hemisphere congeners, such as smaller clutch size, and greater male nest attendance during the incubation period. To assess the consistency of these patterns for the species, we studied breeding biology and parental care of Chilean swallows in Northwestern Argentine Patagonia (41°S). If austral population breeding traits reflect species traits, we predict smaller clutch size, higher female reproductive investment, and similar nest attendance by both sexes during incubation compared to Tachycineta species breeding at similar Northern Hemisphere latitudes. We also anticipate negative correlation between clutch size, egg size, and breeding success with laying date, as observed in Tachycineta species, including Chilean swallows. Surprisingly, clutch and egg sizes did not differ between northern and southern Patagonian populations. We did not find evidence of a negative relationship between clutch or egg size and laying date. Male nest attendance during incubation was variable and low, but their nestlings feeding rates equalled those of females. These findings suggest that Chilean swallows adopt diverse reproductive strategies across regions. This may help this species adapt to different environments and climates, ranging from the shorter breeding seasons and lower summer mean temperatures of Tierra del Fuego to the longer breeding seasons and higher seasonal and daily thermal amplitudes in continental north Andean Patagonia.

Life history changes associated with over 400 generations of artificial selection on body size in Drosophila.

Body size is a trait that shapes many aspects of a species' development and evolution. Larger body size is often beneficial in animals, but it can also be associated with life history costs in natural systems. Similarly, miniaturization, the evolution of extremely small adult body size, is found in every major animal group, yet carries its own life history trade-offs. Given that these effects can depend on an animal's environment and life stage and have mainly been studied in species that are already specialized for their size, the life history changes associated with evolutionary shifts in body size warrant additional investigation. Here, we used Drosophila melanogaster populations that had undergone over 400 generations of artificial selection on body size to investigate the changes in life history traits associated with the evolution of extremely large and extremely small body sizes. Populations selected for small body size experienced strong trade-offs in multiple life history traits, including reduced female fecundity and lower juvenile viability. Although we found positively correlated changes in egg size associated with selection for both large and small body size, after adjusting for female body size, females from populations selected for large size had the lowest relative investment per egg and females from populations selected for small size had the highest relative investment per egg. Taken together, our results suggest that egg size may be a key constraint on the evolution of body size in D. melanogaster, providing insight into the broader phenomenon of body size evolution in insects.

Evolution of Maternal Provisioning and Development in the Ophiuroidea: Egg Size, Larval Form and Parental Care.

The Ophiuroidea is the most speciose class of echinoderms and has the greatest diversity of larval forms, but we know less about the evolution of development (evo-devo) in this group than for the other echinoderm classes. As is typical of echinoderms, evo-devo in the Ophiuroidea resulted in the switch from production of small eggs and feeding (planktotrophic) larvae to large eggs and non-feeding (lecithotrophic) larvae. Parental care (ovoviviparity or viviparity/matrotrophy) is the most derived life history. Analysis of egg data for 140 species (excluding viviparity and facultative planktotrophy) indicated a bimodal distribution in egg volume corresponding to planktotrophy and lecithotrophy+ovoviviparity, with three significant egg size groups due to the very large eggs of the ovoviviparous species. The marked reduction in fecundity in species with extremely large eggs is exemplified by the ovoviviparous species. Egg size in the two species with facultative planktotrophy were intermediate with respect to the two modes. Identifying the ancestral larval life history pattern and the pathways in the switch from feeding to non-feeding larvae is complicated by the two patterns of metamorphosis seen in species with planktotrophic development: Type I (ophiopluteus only) and Type II (ophiopluteus+vitellaria larva). The variability in arm resorption at metamorphosis across ophiuroid families indicates that the Type I and II patterns may be two ends of a morphological continuum. This variability indicates ancestral morphological plasticity at metamorphosis followed by canalization in some taxa to the vitellaria as the metamorphic larva. Vestigial ophiopluteal traits in lecithotrophic ophioplutei and vitellaria indicate evolution from the ancestral (feeding larva) state. Parental care has evolved many times from an ancestor that had a planktonic ophiopluteus or vitellaria and is often associated with hermaphroditism and paedomorphosis. A secondary reduction in egg size occurred in the viviparous species.

Effects of Liquid Whey Supplementation with Water on Egg Production and Egg Quality in Layer Chickens

Background: Liquid whey is a milk by-product and contains good quality protein and minerals. Due to lack of proper knowledge and sufficient technology it remains unutilized and thrown away as a waste. So, keeping in view of its profitable utilization, a study was planned to include liquid whey as feed supplement to layer poultry. Methods: A study was conducted by supplementation of liquid whey to layer chickens to study the effect on egg production and egg quality. A total of 120 layer birds (indicate the age) were supplemented with liquid whey ad libitum in the drinking water @ 0, 5, 10 and 15% up to 90 days. The data were collected with respect to egg production and egg quality parameters. Result: Supplementation of liquid whey in drinking water improved egg production and egg quality in laying chickens. It may be concluded that liquid whey can be supplemented with drinking water at the rate of 5% (v/v) for better egg production in layers and for production of premium quality of bigger size and weight of eggs, supplementation of whey up to 15% (v/v) can be recommended.

Carry-Over Effects of Broodstock Conditioning on the Salinity Tolerance of Embryos of the New Zealand Geoduck (Panopea zelandica)

The New Zealand geoduck (Panopea zelandica) has seen considerable interest from the NZ aquaculture industry. A major bottleneck in culturing P. zelandica is early life stages mortality (e.g., embryo). Therefore, in this study, we investigated the embryonic performance and their transition to the first feeding larval stage (D-veliger) under different salinities (26, 30, 32, and 35 ppt) of four different offspring groups generated from broodstock being fed different ratios (25 : 75, 50 : 50, 60 : 40, and 75 : 25) of the haptophyte Tisochrysis lutea (formerly Isochrysis galbana) (ISO) and the diatom Chaetoceros muelleri (CM) during gametogenesis. Broodstock within all diet ratio treatments successfully conditioned, producing viable embryos. Average egg size ranged between 75 and 80 µm and was not affected by the diet ratios of the broodstock. Survival 48 hr postfertilization, D-veliger larvae yield, and incidence of abnormalities depended on both the embryo rearing salinity and broodstock feeding ratios. The combined salinity of 32−35 ppt and a feeding ratio of 50 : 50 and 60 : 40 (ISO:CM) had the highest survival of embryos (56.0%–77.5%), highest production of D-veliger larvae (>65%), and lowest incidence of abnormalities within D-Veliger (<47%). The size of the larvae decreased with decreasing salinities, with the largest found at 35 ppt (101.22 ± 0.49 µm in shell length). Embryos and larvae did not survive at salinity 26 ppt. These results suggest that diet during gametogenesis can play a role on the offspring ability to cope with environmental stressors at least during the critical first few days after fertilization. These findings provide important information on transgenerational effects due to broodstock diet, especially during the early life stages.

A new species of the genus Paradistomum (Platyhelminthes: Trematoda) from Iwasaki's snail-eating snake Pareas iwasakii, with a note on morphological variations of Paradistomum megareceptaculum (Tamura, 1941).

Dicrocoeliid trematodes were detected from Iwasaki's snail-eating snake Pareas iwasakii in Iriomote Island, Okinawa Prefecture, Japan, and described as a new species Paradistomum dextra n. sp. in the present study. This new species can be distinguished from the type series of the other members of the genus based on size of eggs and morphological characteristics of body, oral and ventral suckers, and reproductive organs. However, the new species was hard to distinguish from Paradistomum megareceptaculum infecting snakes in Japan, including Iriomote Island where is the type locality of the new species, because it is closely similar to some part of the broad range of morphological variations in P. megareceptaculum. On the other hand, a partial sequence of 28S ribosomal DNA clearly distinguished these two species. Moreover, the new species' host snake Pareas iwasakii is reported to exclusively feed on land snails while host snakes of P. megareceptaculum feed on small vertebrates, indicating that the new species is also ecologically different from P. megareceptaculum. We also redescribed P. megareceptaculum based on adults sampled in this study and past studies to record the morphological variations of this species.

Spontaneous Overactivation of Xenopus Frog Eggs Triggers Necrotic Cell Death.

The excessive activation of frog eggs, referred to as overactivation, can be initiated by strong oxidative stress, leading to expedited calcium-dependent non-apoptotic cell death. Overactivation also occurs spontaneously, albeit at a low frequency, in natural populations of spawned frog eggs. Currently, the cytological and biochemical events of the spontaneous process have not been characterized. In the present study, we demonstrate that the spontaneous overactivation of Xenopus frog eggs, similarly to oxidative stress- and mechanical stress-induced overactivation, is characterized by the fast and irreversible contraction of the egg's cortical layer, an increase in egg size, the depletion of intracellular ATP, a drastic increase in the intracellular ADP/ATP ratio, and the degradation of M phase-specific cyclin B2. These events manifest in eggs in the absence of caspase activation within one hour of triggering overactivation. Importantly, substantial amounts of ATP and ADP leak from the overactivated eggs, indicating that plasma membrane integrity is compromised in these cells. The rupture of the plasma membrane and acute depletion of intracellular ATP explicitly define necrotic cell death. Finally, we report that egg overactivation can occur in the frog's genital tract. Our data suggest that mechanical stress may be a key factor promoting egg overactivation during oviposition in frogs.

Productive and Reproductive Performances and Status of Chicken Breeds in Two Districts of South-Omo Zone, Ethiopia

The study targeted the productive and reproductive performance and status of breeds was conducted in two districts of the South-Omo zone, Ethiopia. A purposive sampling method was used to select districts, kebeles, and households and then, stratified to local, exotic, and mixed-breed rearing households. The composition of pullets (3.603), chicks (3.5), and layers (3.39) were highest than that of Cockerels (2.107) and Cocks (1.79). The more eggs/clutch/hen (26.2), the highest matured body weight (3.26 Kg), and the fast age of sexual maturity (5.4 months) were recorded for exotic breeds than the hybrid and local. The hatchability difference was due to the difference in broody hen, egg source, egg duration, egg size, and the season of hatching. The traits such as mothering ability, disease resistance, and production with conditional supplementation of the local breed were diluted. The productive and reproductive performance of the local ecotypes was low and the improved breeds not expressed their full genetic potential. The population of local breeds was diluted and decreased, antagonistically, that of the exotic breeds is increasing, and if it is not terminated near future we will lose distinctive traits of local breeds. Hence, regular supplementation of feed and conservation of exploiting genes were recommended to exploit the full genetic potential of breeds and sustain the diluting genes of local breeds, respectively.

Long-term monitoring of dwarf eggs in clutches of Yellow-legged Gulls (Larus michahellis) breeding in a western Mediterranean colony

The present study provides data on clutches with dwarf eggs from a large sampling in a colony of Yellow-legged Gulls (Larus michahellis) over 31 years. Their occurrence was very low, with a global percentage of 0.26%. Significant variations were not detected among periods of 10 or 11 years. In all the cases, only one dwarf egg was found per clutch. Mean volume of dwarf eggs was 34% of that of non-dwarf eggs. Their content was mostly albumen and a very reduced quantity of yolk, and they were infertile. Several results of the study (the laying order of the dwarf eggs, their mean clutch size and the mean size of the non-dwarf eggs from clutches with dwarf eggs) support the hypotheses that runt eggs occur from a temporary disturbance to the reproductive tract.

Interspecific and intraspecific difference in egg size of two mackerel (Scomber spp.) species in relation to sea surface temperature in the western North Pacific: A new approach to species identification

AbstractChub mackerel (Scomber japonicus, Scombridae) and blue mackerel (Scomber australasicus) are two important fishery resources in the western North Pacific that spawn eggs during the same season. Although estimating the total egg production (TEP) is important for evaluating the spawning stock biomass of mackerel species, it is difficult to accurately identify formalin‐preserved eggs collected during ichthyoplankton surveys. Hence, a new identification criterion that incorporates the effects of water temperature on egg size was developed in this study. The diameter of 37,304 mackerel eggs collected over 16 years (2006–2021) was measured, and frequency distributions of egg size across sea surface temperature (SST) ranges at 1°C interval were constructed. The frequency distributions were classified into two groups using a Gaussian mixture model; based on the results of DNA analysis, the small group was chub mackerel, while the large group was blue mackerel. The SST at the sampling stations and the mean egg size of both groups were negatively correlated. The new identification criterion, incorporating the relationship between SST and egg size, provided reasonable estimates of the TEP of the two mackerel species compared with the conventional criterion. The new species identification approach is applicable to other fish taxa in the western North Pacific.

An Epidemiological Study to Assess the Risk Factors and Symptoms of PCOS

The aim to present this study was to assess the most affected age group of girls from PCOD and to make them aware by our questionnaire in this descriptive study, 200 girls were selected randomly from hostels of MMDU, MULLANA. A questionnaire was formulated to obtain information regarding symptoms, changes, dietary patterns, etc. This data was differentiated, tabulated, and tested. The data collected shows that the majority of the respondents who participated in the survey were on the edge of PCOD. Stein and Leventhal are regarded to have been the first investigators of polycystic ovary syndrome however, in 1721 Vallisneri, an Italian scientist; he described a married, infertile woman with shiny ovaries with a white surface, and the size of pigeon eggs. It was not until early 1990 at a national institute of Health (NIH) sponsored conference on PCOD that formal diagnostic criteria were proposed and afterward largely utilized. Many scientists tried to explain the pathophysiology of PCOS and many studies were made. It is now accepted that it is multifactorial, partly genetic, however, a number of candidate genes have been postulated. Insulin resistance has been noted consistently among many women with PCOS, especially in those with Hyperandrogenism, but it is not included in any of the diagnostic criteria. Now there is strong evidence that cardiovascular diseases risk factors and disturbances in carbohydrate metabolism are all increased in patients with PCOS compared to healthy populations. The criteria was established by a group of experts during a conference in ROTTERDAM held in 2003 are obligatory. The subsequent ROTTERDAM CRITERIA incorporated the size and morphology as determined by an ultrasound of the ovary into the diagnostic criteria. The Center for Disease Control and Prevention, obesity among children in the U.S. has tripled since 1980 due to various factors like bad eating habits, and lack of physical exercise, and many more children are getting more and more obese. Many researchers have found that PCOD findings are increasing with time. Finding insulin resistance in obese adolescents gave a different diagnosis of PCOD. Upon further clinical testing, many other symptoms are found like Hirsutism, acne, and menstrual abnormalities. Emans (2005) described PCOS as a diagnosis related to the diagnosis of insulin resistance, not being overweight. For insulin resistance, females don't need to be overweight, they will have insulin resistance even a normal weight female adolescents also have insulin resistance.

Yacon (Smallanthus sonchifolius) root extracts affect laying performance, egg quality, serum biochemical parameters and intestinal microbiota in hens.

The objective of this study was to investigate the influence of yacon root extracts (YREs) on productive performance and health of laying hens. Six hundred 30-week-old Xiaoshan Chicken layers were divided into 5 groups, control group, antibiotic positive control group, and 3 YREs treatment groups. In a 9-wk feeding experiment, at the end of wk 3, 6, and 9, twenty eggs were collected from each replicate to measure egg qualities. At the end of wk 9, three hen serum samples, and 5 hen cecal content samples were collected from each replicate. Compared to the control group, 0.8%, 1.6%, and 2.4% YREs treatments could increase hens' daily feed intake, and YREs supplementation affected daily feed intake in linear manner. YREs did not change egg size, but 0.8% and 2.4% YREs changed egg shape by decreasing the egg shape index and sphericity, and 0.8% YREs tended to improve the eggshell breaking strength. Diet supplemented with 1.6% YREs might decrease yolk color grade but optimize the pH of thick egg white in fresh egg; moreover, 1.6% and 2.4% YREs might be helpful for eggs to inhibit water loss during storage, and YREs supplementation affected water loss rate in linear manner. 2.4% YREs could decrease the serum lactate dehydrogenases (LDH) level, and YREs supplemental levels linearly affected serum LDH content. Finally, YREs could enrich the diversity of intestinal microbiota of hens fed with 0.8% and be beneficial for the relative abundance of phylum Bacteroidota and Halobacterota; 2.4% YREs might increase the abundance of phylum Actinobacteriota and genus Bifidobacterium, while decrease genus Bacteroides; YREs supplemental levels affected the abundance of phylum Actinobacteriota, and genera Bifidobacterium and Bacteroides in linear manner. Dietary supplementation with YREs could affect egg quality, protect the health of organs and exhibit prebiotic activity.

Population density effects on gamete traits and fertilisation dynamics under varying sperm environments in mussels.

Gamete traits can vary widely among species, populations and individuals, influencing fertilisation dynamics and overall reproductive fitness. Sexual selection can play an important role in determining the evolution of gamete traits with local environmental conditions determining the strength and direction of sexual selection. Here, we test for signatures of post-mating selection on gamete traits in relation to population density, and possible interactive effects of population density and sperm concentration on sperm motility and fertilisation rates among natural populations of mussels. Our study shows that males from high-density populations produce smaller sperm compared with males from low-density populations, but we detected no effect of population density on egg size. Our results also reveal that females from low-density populations tended to exhibit lower fertilisation rates across a range of sperm concentrations, although this became less important as sperm concentration increased. Variances in fertilisation success were higher for females than males and the effect of gamete compatibility between males and females increases as sperm concentrations increase. These results suggest that local population density can influence gamete traits and fertilisation dynamics but also highlight the importance of phenotypic plasticity in governing sperm-egg interactions in a highly dynamic selective environment.

Life cycle traits, secondary production and DNA barcode of Oxyurella ciliata Bergamin, 1939 (Crustacea, Branchiopoda, Anomopoda, Chydoridae)

This study the life cycle and quantify the secondary production of the cladoceran Oxyurella ciliata under controlled conditions in a laboratory and use molecular biology as a tool to investigate its genetic characteristics. The organisms were collected from Baia do Gerente, a pond from the Pantanal region, MS state, Brazil. They were acclimatized, maintained at a controlled temperature (25 ± 1 °C) and photoperiod (12/12h light-dark), fed with the microalgae Raphidocelis subcapitata and observed daily to obtain the data. O. ciliata had a high total egg production of 34.18 ± 9.68 eggs/female and an average longevity of 58.50 ± 16.30 days. These values differed from those previously reported for O. longicaudis, another congeneric species. There was an exponential growth of biomass until instar 6 and the largest secondary production was from the young to the adult phase, which corresponds to the beginning of the reproductive phase. The molecular data revealed that the genetic divergence between the sequence of O. ciliata and that of O. longicaudis is approximately 18 %, which seems high considering that both belong to the same genus. Comparing life cycle data and DNA Barcode, Oxyurella ciliata and O. longicaudis are very distant and have distinct morphological and biological characteristics, such as: body size, egg size, growth, fertility, longevity and development times. This study highlights the importance of molecular studies and information on the life cycle of neotropical cladocerans, in an integrated way, to have a better taxonomic and ecological interpretation of the species.

Variation in reproductive traits associated with different host plants in the subsocial bug Elasmucha putoni (Hemiptera: Acanthosomatidae)

ABSTRACTHost plants are an important selective factor for the evolution of reproductive traits in herbivorous insects. Among different host plants, offspring will be exposed to different environmental conditions, and parents are expected to allocate reproductive resources adaptively to their offspring according to such environmental heterogeneity. Elasmucha putoni Scott (Hemiptera: Acanthosomatidae) is a bivoltine shield bug showing maternal care. We examined the variation in reproductive traits, that is, egg size, clutch size and the trade‐off between them, between two generations of a population and two populations of the same (later) generation, which differ in their host plants. Controlling for female body size, a significant difference was detected in egg size, but not in clutch size between the earlier generation on Morus australis and the later one on Euptelea polyandra or Rosa multiflora. Moreover, there was no difference in the two traits between the populations (one using E. polyandra and another using R. multiflora) of the same generation. A significant trade‐off between egg size and clutch size was detected in the earlier generation on M. australis but not in the later generation on E. polyandra or R. multiflora. This is the first study indicating variable reproductive allocation according to different host plants in herbivorous insects with maternal care.

Species-Specific Seasonal Shifts in Reproductive Allocation in the Southern Grass Lizard, Takydromus sexlineatus (Lacertidae).

We designed a common garden design to collect data on female reproductive traits from three populations of the southern grass lizard Takydromus sexlineatus, testing the hypothesis that a species-specific pattern of seasonal shifts in reproductive allocation should be shared by geographically separated populations. Of the seven examined traits, six differed among populations, with four of the six also differing among successive clutches. Females grew longer during the breeding season and produced more eggs in the first clutch than in the subsequent clutches; egg size was unchanged throughout the breeding season. After removing the influence of female size or postpartum body mass we found the following. First, postpartum body mass, clutch mass, and relative clutch mass were greater in the Wuzhishan population than in the Shaoguan and Zhaoqing populations. Second, egg size was greatest in the Wuzhishan population and smallest in the Zhaoqing population. Third, clutch size was greatest in the Wuzhishan population and smallest in the Shaoguan population. Females did not trade-off egg size against number within each population × clutch combination. Our study validates the hypothesis tested, supports the conventional view that reproductive output is highly linked to maternal body size in lizards, and follows the classic prediction that females with different amounts of resources to invest in reproduction should give priority to adjusting the total number rather than size of their offspring.

Larval competition between three endemic fruit flies (Diptera: Tephritidae) of differing phylogenetic relatedness

AbstractWithin a fruit, fruit fly larvae can be subject to scramble competition, in which density‐dependent effects can influence the fitness of subsequent adults. While there is significant research on tephritid interspecific larval competition, it has been conducted in invasive situations where the species are evolutionarily novel to each other. There has been no published research investigating larval competitive interactions between naturally coexisting, endemic species. We ran laboratory‐based, intraspecific and interspecific larval competition trials involving three co‐occurring Bactrocera species of differing genetic relatedness and also measured aspects of juvenile development rate to test possible mechanisms of competitive difference. Larval density had an influence on intraspecific competition in Bactrocera tryoni, Bactrocera neohumeralis and Bactrocera jarvisi, with a decreasing percentage of pupation with increasing larval density. Interspecific competition between B. tryoni and B. neohumeralis, and between B. tryoni and B. jarvisi was influenced by the interaction between species and density. The intensity of competition between B. tryoni and B. neohumeralis was minimal but high between B. tryoni and B. jarvisi. B. jarvisi produced larger eggs and had faster initial larval growth rates than the other two species, but it took the longest time for pupation to occur. Our results conflict with theory, as the greatest competition was observed between the two more distantly related species (B. tryoni and B. jarvisi) rather than between the two most closely related species (B. tryoni and B. neohumeralis). Further, and contrary to other studies, egg size, hatch rate and larval growth rate did not provide B. jarvisi with a competitive advantage; thus, larval size does not appear to be a mechanism of larval competition between B. tryoni and B. jarvisi.

On population structure and breeding biology of burrowing crab Dotilla blanfordi Alcock, 1900.

The present study investigated the population structure and breeding biology of the burrowing brachyuran crab species Dotilla blanfordi Alcock, 1900, which is commonly found on the sandy beach of Bhavnagar, located on the Gulf of Kachchh, Gujarat coast, India. Monthly sampling was conducted from February 2021 to January 2022 at the time of low tide using three line transects perpendicular to the water line, intercepted by a quadrate (0.25 m2) each at three different levels of the middle intertidal region: 20 m, 70 m, and 120 m. The quadrate area was excavated up to 30 cm and sieved for specimen collection. The collected specimens were categorised into different sexes viz., male, non-ovigerous female, or ovigerous female. For the fecundity study of D. blanfordi, the carapace width (mm) as a measure of size as well as their wet weight (g), size, number, and mass of their eggs were also recorded. The study revealed sexual dimorphism among the population, with females having significantly smaller sizes as compared to males. The overall population was skewed towards females, with a bimodal distribution of males and females. The occurrence of ovigerous females throughout the year suggests that the population breeds incessantly throughout the year, with the highest occurrence in August and September. A positive correlation was observed between the morphology of crabs (carapace width and wet body weight) and the size, number, and mass of eggs.

Description of Saccocoelioides miguelmontesi n. sp. (Digenea: Haploporidae) from characid fishes in the Iguazu River Basin based on morphological and molecular evidence.

Here we describe a new species of the genus Saccocoelioides found parasitizing Astyanax dissimilis Garavello & Sampaio, Psalidodon bifasciatus (Garavello and Sampaio) and Bryconamericus ikaa Casciotta, Almirón & Azpelicueta from the Iguazu National Park, Misiones province, Argentina. Saccocoelioides miguelmontesi n. sp. was studied based on morphological and molecular (28S rDNA and COI mtDNA sequences) data. The COI mtDNA tree indicated that the specimens collected from the three fish hosts are conspecific, with an intragroup p-distance of 0%. The new species shows an intermediate morphological configuration between the diminutive and robust forms described for Saccocoelioides by Curran (2018). Although, in the 28S rDNA tree, it is placed in a well-supported clade with the two robust species analysed (S. elongatus and S. magnus; p-distance of 1 and 2%, respectively), it differs from the robust group by the range of body size, mature egg size, oral and ventral sucker size, sucker ratio, oral sucker to pharynx ratio, and post-cecal or post-testis/body length percentage. Our results led us to redefine the robust group as having eggs shorter or equal in length to the pharynx. Saccocoelioides miguelmontesi n. sp. the 10th species reported from Argentina and the 7th species within the robust group.