Carapace Length Research Articles

Shell Constraints on Evolutionary Body Size-Limb Size Allometry Can Explain Morphological Conservatism in the Turtle Body Plan.

Turtles are a small clade of vertebrates despite having existed since the Late Triassic. Turtles have a conservative body plan relative to other amniotes, characterized by the presence of a shell and quadrupedality. This morphology is even retained in strong ecological specialists, such as sea turtles, which are secondarily adapted to marine locomotion by strong allometric scaling in their hands. It is possible that the body plan of turtles is strongly influenced by the presence of the shell, acting as a constraint to achieving greater diversity of body forms. Here, we explore the evolutionary allometric relationships of fore- and hindlimb stylopodia (i.e., humerus and femur) with one another as well as their relationship with shell size (carapace length) to assess evidence of constraint. All turtles, including Triassic shelled stem turtles, have near-isometric relationships that do not vary strongly between clades, and evolve at slow evolutionary rates. This indeed indicates that body proportions of turtles are constrained to a narrow range of possibilities. Minor allometric deviations are seen in highly aquatic sea turtles and softshell turtles, which modified their shells by bone losses. Our allometric regressions allow accurate body size estimations for fossils. Several independent sea turtle lineages converged on maximum sizes of 2.2 m of shell length, which may be a biological maximum for the group.

Growing older, growing more diverse: Sea turtles and epibiotic cyanobacteria.

Cyanobacteria are known for forming associations with various animals, including sea turtles, yet our understanding of cyanobacteria associated with sea turtles remains limited. This study aims to address this knowledge gap by investigating the diversity of cyanobacteria in biofilm samples from loggerhead sea turtle carapaces, utilizing a 16S rRNA gene amplicon sequencing approach. The predominant cyanobacterial order identified was Nodosilineales, with the genus Rhodoploca having the highest relative abundance. Our results suggest that cyanobacterial communities become more diverse as sea turtles age, as we observed a positive correlation between community diversity and the length of a sea turtle's carapace. Since larger and older turtles predominantly utilize neritic habitats, the shift to a more diverse cyanobacterial community aligned with a change in loggerhead habitat. Our research provides detailed insights into the cyanobacterial communities associated with loggerhead sea turtles, establishing a foundation for future studies delving into this fascinating ecological relationship and its potential implications for sea turtle conservation.

The contribution of fish to the diet of loggerhead sea turtles in the western Mediterranean revisited

Early juvenile loggerhead turtles (Caretta caretta) rely on gelatinous zooplankton, whereas individuals larger than 40 cm curved carapace length are adapted to crush hard-shelled invertebrates. Nevertheless, fish were reported to be the staple food of loggerhead turtles in the western Mediterranean 30 years ago. Here, the temporal consistency of such a fish-based diet of loggerhead turtles is assessed through gut content analysis and stable isotope analysis of samples from the Mediterranean coast of Spain spanning three decades. The gut contents of 134 juvenile loggerhead turtles (curved carapace length range: 27–71 cm) from three different periods (1991, 1999–2008 and 2010–2017) were analyzed, as well as a subsample of the same turtles (n = 10 in each period) for both bulk and compound-specific stable isotope ratios (CSIA-AA). Gut content analysis revealed a decline in the frequency of occurrence and numerical abundance of fish and an increasing contribution of gastropods and bivalves throughout time, although pelagic tunicates were always the most frequently observed prey. The δ15Nbulk of turtle bone also dropped throughout the study period, but the values of the stable isotope ratio of N in phenylalanine (δ15NPhe) indicated that 52.5% of that variability was due to a baseline shift over time. Accordingly, the trophic position estimated from CSIA-AA did not follow the decreasing pattern of δ15Nbulk, but fluctuated throughout time. The overall evidence indicates that fish consumption by loggerhead turtles in the study region declined through time, but the trophic position of loggerhead turtles did not change simultaneously. This is probably because low trophic prey such pelagic tunicates and filter-feeding bivalves and suspension-feeding gastropods were the bulk of the diet during the whole study period and fish played a minor role, even when their frequency of occurrence peaked. Past levels of high fish consumption might be due to high levels of fishery discards, currently declining because of the recent reduction of the fishing fleet.

Enhancing Sustainability and Conservation of White Shrimp Penaeus schmitti in Northeast Brazil: Insights Into Life History, Reference Points, and Management Strategies for Beach Seining

ABSTRACTArtisanal fishing significantly not only contributes to socioeconomic development of numerous countries but also exerts pressure on natural populations. The white shrimp (Penaeus schmitti) is a key species in Brazilian artisanal fisheries, yet it is currently classified as data‐deficient. Conducting comprehensive studies on its population dynamics is essential to establish reference points that guarantee sustainable fishing. Therefore, we estimated population parameters to assess status of the white shrimp stock captured by beach seining in Northeast Brazil. Monthly samples of white shrimp were collected using a beach trawl. Based on population parameters, the white shrimp population in the study area, the sex ratio was 1 male to 1.29 females, with females larger and heavier than males. Weight–length relationships revealed positive allometric growth for males, females, and grouped sexes, with no significant difference between sexes. Asymptotic length, t_achor, and growth performance index also did not differ between sexes; however, the growth coefficient was higher for females. Beach trawling in northeastern Brazil predominantly targeted adult white shrimp, with carapace length at first capture (Lc50) averaging 2.12 cm for females and 2.19 cm for males. Mortality and exploitation rates were below maximum sustainable levels, so the stock was classified as underexploited. Overall, beach‐seine fishing was less harmful to this stock (F = 1.42) than motorized fishing and can be considered a sustainable fishing activity for the white shrimp population.

Age and growth rate estimated by skeletochronology in loggerhead sea turtles from French Mediterranean waters

Abstract Skeletochronology was used to determine the ages of 30 loggerhead sea turtles (Caretta caretta) found in French Mediterranean waters. Histological sections were performed with 30 humeri collected on stranded C. caretta on the coast of Provence and the Gulf of Lion. Lines of arrested growth (LAGs) were used to evaluate age, considering only one period of arrested growth per year. Two successive LAGs delimit an interval that is proportional to the individual’s body growth. In a first step, we created a skeletogram for each individual that identified its LAGs. Secondly, we measured the areas delineating successive intervals to determine individual growth patterns over the years. Two methods were used to deduce sea turtle age from histological sections: the correction factor (CF) method and the growth rate (GR) method, the latter using Von Bertalanffy growth function. Age estimations varied from 4.3 to 24.7 years (mean ± SD = 10.1 ± 4.8) with the CF method and from 6.2 to 25.6 years (mean ± SD = 12.2 ± 5.2) with the GR method, with no significant difference between the methods. The study sample was thus mostly composed of juveniles, which is also the most frequent life stage observed in the study area. The annual curved carapace length growth rate calculated with every LAG interval varied from 1.0 to 6.9 cm/year (mean ± SD = 3.5 ± 1.4, ). High variability in interindividual growth rates were observed, which is of interest in understanding the complex lifecycle of these long-lived marine reptiles.

Spiny lobster recreational fisheries in Australia and New Zealand: An overview of regulations, monitoring, assessment and management

Spiny (rock) lobsters occur globally and, although harvest is dominated by commercial fisheries, it is important to account for recreational harvest in stock assessments and fisheries management. This paper provides a contemporary review of recreational fishing for five spiny lobster species in Australia and New Zealand. Each jurisdiction has established approaches for collecting data which best meet their information needs (telephone-diary or telephone-recall surveys, charter logbooks, tag reporting). Jurisdictions with specific spiny lobster licences (Western Australia, Tasmania) or mandatory reporting (charter logbooks in Western Australia, tag reporting in Victoria) use these registers as a sampling frame for annual reporting of participation, fishing effort, catch (numbers) and harvest (tonnes). All other jurisdictions use a general fishing licence or general population sampling frame for telephone-diary surveys to provide periodic reporting of catch and harvest. Annual participation in spiny lobster recreational fishing was highest in Western Australia (35,236 ± SE 626 fishers in 2022–23), followed by Tasmania (13,715 ± SE 1067 fishers in 2022–23) and Victoria (5516 fishers in 2020–21). Annual recreational harvest of all spiny lobster species, combined for the most recent data collection period in each jurisdiction, was 830 tonnes; consisting mostly of Western Rock Lobster (Panulirus cygnus) from Western Australia and Southern Rock Lobster (Jasus edwardsii) from Tasmania and New Zealand. This review illustrates the various spatial scales of monitoring, reporting and assessment in each jurisdiction. All monitoring provides information on catch and harvest, with some also reporting participation, effort, carapace length and non-catch related variables. The designs underlying these approaches vary from probability-based (opt-out) and census (mandatory), and it is important to understand the benefits and inherent biases of each. Understanding the parallels between jurisdictions offers valuable insights into how to cost-effectively monitor spiny lobster recreational fisheries and integrate this data into stock assessment and harvest strategies to support sustainable fisheries into the future.

Growth patterns and condition factors of introduced crayfish population in Rawa Aopa-Watumohai National Park

Abstract Crayfish as an introduced species is now the primary catch of fishermen in the marsh ecosystems of Rawa Aopa-Watumohai National Park. Despite its significant economic impact on the area, caution is advised due to this species’ high ability to infiltrate a new ecosystem as a competitor, predator, pathogen, or parasite carrier. However, preliminary research is necessary to determine its basic biological elements, such as growth patterns and condition factors, as there is currently no information available for the ecosystem. A simple random sampling technique was used with 24 traps at 3 sites to catch the 810 total crayfish. The analysis results showed that the carapace length range was 19.5-99.4 mm predominantly by middle-size crayfish (44.4-60.9 mm). Based on the length-weight relationship by sex and month, the growth pattern was found negatively allometric (b:1.59-2.31) with strong correlations between length and weight (>0.9) indicating that the crayfish was thin. The result of the condition factor analysis by sex and month also showed that the crayfish was not plump (K:1.01–1.07). The crayfish’s body in the national park was shorter, thin, underweight, or generally unhealthy compared to crayfish from other areas of Indonesia. These results suggested that the population was likely suppressed by natural or human-related factors, necessitating a further study of the species’ other biological aspects.

Lost but not forgotten: Rediscovery of the Ukrainian Lepidurus middendorffii (Braem, 1893) (Branchiopoda: Notostraca) through integrative taxonomy

Abstract The taxonomy of the notostracan LepidurusLeach, 1819 is complicated by a large number of synonymised species and extensive intraspecific variability in many relevant characters. We demonstrate, based on an integrative taxonomic approach, that the Ukrainian populations of Lepidurus are not conspecific with any currently accepted Lepidurus species and assign them to the previously synonymised species Lepidurus middendorffiicomp. nov. (Braem, 1893). This species exemplarily highlights the problems in the taxonomy of Lepidurus. The species was originally described as Apus extensus var. middendorffii (Braem, 1893), but L. extensus is a junior synonym of Lepidurus lubbocki (Brauer, 1873), which is currently treated as a subspecies of Lepidurus apus (Linnaeus, 1758). Our molecular genetic analyses based on mitochondrial COI, 12S, 16S, and nuclear 28S, which included published data, suggest the presence of further, possibly cryptic species that await formal recognition and stress the importance for a more extensive revision of Lepidurus. The original type specimens of L. middendorffii, previously stored at the Museum of Natural History (Wrocław University, Wrocław, Poland), are lost and a neotype is designated. Lepidurus middendorffii is characterised by the dorsal organ position between the ocular tubercle margins, the sharp carapace sulcus spines, the long supra-anal plate with many median spines, a telson length to carapace length ratio 0.18–0.35, and differs by > 9% uncorrected COI p-distances from all other Lepidurus species.

An update on female sizes and body condition of nesting olive ridley turtles (Lepidochelys olivacea) in La Escobilla Beach Sanctuary, Mexico

Body condition (BC) can affect the reproductive output and hatchling survival of nesting olive ridley turtles (Lepidochelys olivacea). However, little is known about the BC of nesting females during the arrival event at nesting sites. Therefore, this study aimed to evaluate the BC of females nesting in La Escobilla Beach Sanctuary (La Escobilla) during the 2021 nesting season. Nesting females were measured and weighed. The mean size for nesting L. olivacea was 60.41 ± 2.98 cm for straight carapace length, 52.69 ± 2.57 cm for straight carapace width, and 34.35 ± 3.94 kg for weight (n = 483). The mean (± standard deviation, SD) Fulton's/Bjorndal BC index estimated for nesting females was 1.54 ± 0.15, while the mean (± SD) of body mass index was 2.18 ± 0.23. Based on these indexes, 28 individuals were classified as in bad condition, 315 in good condition, and 19 in excellent condition. This first estimation of the olive ridley turtle body condition in a nesting colony showed that BC is a good body condition for most nesting females in La Escobilla. This study is a valuable baseline for nesting L. olivacea's health condition.

Reproductive Dynamics of Spot Tail Mantis Shrimp (Squilla mantis): Insights from the Central Mediterranean Sea.

Fisheries management requires improvement in scientific knowledge to ensure sustainable exploitation of important commercial species and population renewal. Within this context, this study focused on the reproductive biology of spot tail mantis shrimp, Squilla mantis, in the Central Mediterranean Sea, aiming to understand the reproductive pattern of this species and validate the macroscopic maturity scale through histological analysis. A multi-year sampling was performed from 2016 to 2020 by a commercial fishing fleet in the Northern Central Adriatic Sea (GSA 17), and a total of 2206 individuals were collected. The monthly average value of the total sex ratio of S. mantis was 0.524 ± 0.044 (mean ± SEM) in favor of females, which dominated the population from September to April. The proposed 5 stage macroscopic maturity scale was validated histologically through histological analysis, confirming synchronous ovarian development. The somatic indexes (GSI and K Fulton) and monthly incidence of macroscopic ovarian maturity stages highlighted a protracted reproductive season from winter to spring (January-May). Although the length-weight relationship showed a similar growth trend between genders, males reached a bigger size in terms of carapace length (C.L.) and dominated the population from 32 mm (C.L.). The macroscopic L50 estimated was 25.94 mm (C.L.).

Relative growth, sexual dimorphism, and sexual maturity of the freshwater shrimp Macrobrachium jelskii (Miers, 1877) (Caridea: Palaemonidae)

ABSTRACT Macrobrachium jelskii is an endemic shrimp species of South America, with a wide geographical distribution. Although there have been some studies on this organism, information regarding the relative growth of body structures has never been fully explored. In this regard, we aim to analyse the relative growth of this species, in order to investigate the developmental pattern between juveniles and adults, as well as to estimate the morphological sexual maturity (MSM). For morphometric analysis and MSM estimation, the following structures were measured: carapace length (CL); abdomen length (AL); propodus (CPL) and dactyl length (DL) of the second pair of pereopods; second pleonal pleuron width (SPW); and appendix masculina length (AML). We observed developmental differences between juveniles and adults, especially in males. The MSM size for males was estimated at 7.47 mm CL, while for females it was 8.77 mm CL. Females exhibit significantly larger sizes compared to males. Our study reveals divergent energy allocation between juvenile and adult M. jelskii, with males and females reaching MSM at different sizes. The development of these structures with varying allometric constants throughout life stages suggests a strong connection to reproductive behaviour, meeting the specific needs of each life stage’s behavioural repertoire.

Growth, mortality, and exploitation rates of the mantis shrimp Erugosquilla massavensis (Kossman, 1880) (Malacostraca: Stomatopoda) in Iskenderun Bay, north-eastern Mediterranean of Türkiye

ABSTRACT Lessepsian Erugosquilla massavensis is one of the three Stomatopod species reported on the Levantine coast of Türkiye. Its natural habitat is the Red Sea and it is the first Red Sea stomatopod species reported from the Mediterranean. This study aims to determine the morphometric relationships, growth parameters, sex ratio, age, mortality, and exploitation rates of non-native E. massavensis in the north-eastern Mediterranean. Samples were collected monthly by commercial trawl surveys between September 2016 and March 2017 in Iskenderun Bay. Relationships between the carapace length (CL)–total length (TL) and the total length (TL)–total weight (TW) were estimated. Negative allometric growth was observed between the CL–TL and TL–TW relationship for females, males, and all. The von Bertalanffy growth parameters (vBGP) were found L ∞ = 155.4 mm, K = 0.520 year−1, t 0 = −0.199, ø′ = 4.099 for females, L ∞ = 157.5 mm, K = 0.600 year−1, t 0 = −0.127, ø′ = 4.173 for males. This research provided the first-ever data on the vBGP of E. massavensis. The study found that both sexes had a higher fisheries mortality coefficient than natural mortality (Z = 2.01, M = 0.71, F = 1.3) and were exploited (E = 0.65).

Reproductive traits of Gnathophylloides mineri Schmitt, 1933, a minute ectosymbiotic shrimp associated with the sea urchin Tripneustes ventricosus

Abstract Numerous studies on the reproduction of decapods have revealed that the female energy investment in embryo production is generally around 10% of the female weight. In decapods living together with other organisms, however, the reproductive output (RO) may be substantially higher. Here we tested the hypothesis that decapods living in association with other organisms allocate more energy in embryo production than free-living ones. We studied the shrimp Gnathophylloides mineri, which lives among the spines of the sea urchin Tripneustes ventricosus. Shrimps were collected between October 2011 and April 2013 along the southern Caribbean coast of Costa Rica. A total of 45 ovigerous females were analyzed; female size ranged from 1.44 to 2.14 mm carapace length. Females carried on average 37 ± 16 SD embryos. The embryo volume increased during the incubation period by 200% (from 0.04 ± 0.01 to 0.08 ± 0.01 mm3, mean ± SD). The RO was not related to female size, and comprised on average 27.5 ± 16.0 SD % of the dry weight of the females. In summary, G. mineri produces few and small embryos, but these embryos are relatively large when compared to similar-sized caridean species. Moreover, RO of this ectosymbiotic species was higher than in free-living species, but lower than in endosymbiotic decapods. These results support the hypothesis that energy investment in embryo production of decapods increases with the level of protection associated with the symbiosis.

Correlations between local geoclimatic variables and hatchling body size in the sea turtles Caretta caretta and Chelonia mydas

It has been widely demonstrated that air and sand temperatures influence the anatomy of sea turtle hatchlings. We examined the impact of precipitation during the nesting season on the hatchling body size of loggerhead and green turtles from 37 beaches worldwide. Longitudinal data collected between 2012 and 2018 from Florida (US) and from a sample on Bõa Vista Island (Cabo Verde) carried out in 2019 showed that loggerhead body size at hatching was negatively correlated with precipitation, while precipitation was not correlated with hatchling body size in green turtles. A meta-analysis revealed that precipitation is positively correlated with hatchling mass in loggerhead turtles, while it is positively correlated with straight carapace length and width in green turtle hatchlings. The strongest influence of precipitation was found in the middle of the incubation period of loggerhead turtles in Cabo Verde, and we posit that this is due to an increase in the uptake of water for embryonic growth. These findings highlight the great importance of understanding the correlated effects of regional environmental variables, such as precipitation, on the development of sea turtle hatchlings and will have an impact on the evaluation of ongoing conservation and climate change discussions.

Estimation of Additive and Dominance Genetic Variances for Growth and Multiple Stress at Different Ages in Pacific White Shrimp Litopenaeus vannamei

AbstractThis study aimed to estimate the additive and dominance genetic variance in growth and multiple‐stress tolerance traits in 7‐week‐old and 15‐week‐old Pacific white shrimp Litopenaeus vannamei. Four different animal models were studied by including all or different subsets of the following effects: additive genetic effects (A), additive genetic and common environmental effects (A + C), additive genetic and dominance effects (A + D), and additive, common environmental, and dominance effects (A + D + C). Variance components were estimated using the average information restricted maximum likelihood method. In general, estimates of additive genetic variance were inflated under the simple model (A) and decreased remarkably under the more complex models (A + C, A + D, and A + D + C). The genetic parameters of two‐stage (7‐week and 15‐week shrimp) growth and multiple‐stress tolerance traits were more suitable for estimation using the A + C model. The additive effects (0.311–0.754) of seven traits in 7‐week shrimp were greater than the dominance effects (4.950 × 10−7 to 0.201), whereas the additive effects of the same seven traits in adult shrimp ranged from 7.712 × 10−8 to 0.468 and the dominance effects ranged from 0.074 to 0.577. Except for survival time, carapace length, and carapace width, the additive effects of the other traits were smaller than the corresponding dominance effects. Thus, better genetic improvement of 7‐week and 15‐week shrimp growth and multiple‐stress tolerance can be obtained with selective breeding than with crossbreeding and better genetic improvement of 7‐week shrimp growth traits can be obtained with crossbreeding than with selective breeding. Our study further enriches the database for enhancing growth and stress resistance in Pacific white shrimp and provides reference information for growth improvement and multiple‐stress resistance breeding.

Functional morphology and ontogeny of mouthparts and mouth aperture of Panulirus ornatus and Sagmariasus verreauxi: Implications towards formulated feeds development

Development of formulated feed is now a focal point in advancing the aquaculture of spiny lobster species. This study investigated the functional morphology of two spiny lobsters, Panulirus ornatus and Sagmariasus verreauxi, by analysing mouthpart morphology and mouth aperture. The analysis is focussed on determining likely feed preference based on morphology with the aim to provide knowledge for the development of formulated feeds. There is a strong correlation between the mouth aperture being approximately 4.0 and 7.5% of the carapace length of S. verreauxi and P. ornatus juvenile and adult lobsters, respectively. This finding provides knowledge for development of a species-specific tool that could be used in experimental studies to define optimal dimensions of artificial manufactured pellets in relation to the size of the lobster. Differences in mouthpart morphology through ontogeny included increase of calcification and robustness, and this is likely to reflect a different requirement in the texture (softness/hardness) of the pellet as the animals develop. Spines and setation are a prominent feature of the mouthpart morphology and differ between species and during ontogeny. Spines on maxillipeds II and III and crista dentata on maxillipeds III are likely to play an important role in holding and manipulation of feed prior to ingestion. Pellet texture may need to accommodate these differences in species and age specific mouthpart ontogeny. Ontogenetic changes in setation were found, with much richer setation proportionally to the size of mouthpart in first instar juvenile lobsters, which decreases with size increase. Furthermore, species-specific differences indicate function shifts in mouthparts with life stages. This may indicate differences in filter feeding capacity with age and between species, as reported for other decapods. This is unlikely to be of high importance in pellet feeding but may represent an avenue of investigation for first feeds in juveniles. Collectively, the differences during ontogeny and between species suggest that formulated feeds may need to be tailored to species and life stage, particularly regarding pellet dimensions and texture.

Development and validation of a 40 K liquid SNP array for the mud crab (Scylla paramamosain)

Genomic selection (GS) and genome-wide association studies (GWAS) have been widely implemented to accelerate the genetic improvement of important economic traits. Developing an efficient and reliable high-throughput genotyping tool is the premise and basis of implementing GS and GWAS on the mud crab (Scylla paramamosain). In this study, leveraging the whole-genome resequencing data of 146 mud crabs from the southeast coast of China, a total of 16,714,943 high-quality SNPs were discovered. Based on polymorphic information content and evenly distribution on 49 chromosomes, a total of 40,352 SNPs was selected to develop a 40 K liquid SNP array (named “Xiexin No. 1”) using the genotyping by target sequencing (GBTS) technology. The genotyping performance test showed that this SNP array had a high site polymorphism (over 92.70%) and individual calling rate (97.02%). Furthermore, the mean of SNP concordance, genotype concordance, non-reference sensitivity, and non-reference discrepancy between “Xiexin No. 1” SNP array and resequencing were identified to be 0.986, 0.954, 0.942, and 0.097, respectively. Using this SNP array data, the genomic heritabilities were evaluated as 0.887 ± 0.065, 0.643 ± 0.108, 0.599 ± 0.111, and 0.624 ± 0.111 for body weight (BW), carapace length (CL), carapace length (CW), and body height (BH) in a cultured population (233 crabs). Furthermore, five significant SNPs associated with growth traits were identified by GWAS. After annotation, one candidate gene (XP_027221997.1) associated with BW and one candidate gene (XP_027210446.1) associated with CW and BH were identified. Most importantly, the prediction accuracy of GBLUP for BW, BH, CL, and CW were 0.535 ± 0.064, 0.544 ± 0.101, 0.574 ± 0.087, and 0.585 ± 0.083, with the unbiasedness values of 0.988 ± 0.22, 1.015 ± 0.274, 1.011 ± 0.196 and 1.037 ± 0.235. In conclusion, the “Xiexin No. 1” SNP array provides an efficient and reliable platform for high-quality genotyping, which would greatly promote the genetic studies and thus accelerate the genetic improvement of mud crabs.

Reproductive ecology of the critically endangered pancake tortoise (Malacochersus tornieri) in the wild

Reproduction of the pancake tortoise in the wild has remained poorly known over the decades. This study fills the knowledge gap by investigating the reproductive ecology of the species in its natural habitats in Kenya. Data were collected using the time‐constrained search‐and‐seize method, group‐level scan sampling, radio tracking, and camera‐trapping. Our observations revealed a total of 19 mating events that occurred between December and April, predominantly during the rainy seasons. Mating duration averaged 15.2 ± 2.4 min. Male–male aggression was observed during the mating season, with the dominant male keeping off all other males and mating with the resident females. Nest preparation events occurred between April and June. Nine nesting events were recorded, but in only five of them was an egg deposited. The nests were dug in loose soil, appeared almost circular, and measured 8.4 ± 0.9 cm wide and 7.0 ± 0.1 cm deep (n = 7). The average clutch size was one egg. The eggs were white, hard‐shelled, oval, and elongated measuring 4.4 ± 0.4 cm long, 2.7 ± 0.04 cm wide and weighed 17 ± 0.6 g (n = 3). Incubation period lasted 177 ± 5.7 days (n = 2), and hatching coincided with the onset of the short rainy season in November, aligned with the availability of abundant food for the tortoises. The hatchlings were minimally wider than long, having an average straight carapace length of 4.5 ± 0.6 cm, an average width of 4.5 ± 0.4 cm, and on average weighed 14.7 ± 3.7g, (n = 9). They remained near the nest site for 4–5 days before relocating to tiny rock crevices away from the adult tortoise crevices. Egg and hatchling predation was high, with four of the total of six eggs, observed after they were laid, being destroyed. Three juveniles, out of nine, were also eaten by predators. These findings contribute useful information for the formulation of effective conservation and management strategies for this critically endangered species.

Macrobrachium ngankeeae, a new species of freshwater shrimp (Crustacea: Decapoda: Palaemonidae) from Papua Barat Province, Indonesia

A new freshwater prawn, Macrobrachium ngankeeae n. sp., is described from two rivers in the Kaimana Regency on the southern coast of Papua Barat Province, Indonesia. The new species belongs to the Macrobrachium placidulum species-group, but it can be easily distinguished from the other members of this group by having fewer postorbital teeth and the epigastric tooth placed more anteriorly with a relatively shorter epigastric length, i.e. 0.23–0.27 of carapace length (vs 0.24–0.55 in the other species members). Other distinguishing morphological characters and a molecular analysis of this new species are discussed. A key to the species of the M. placidulum species-group is also provided.

Insights into ovarian maturation and reproductive traits of the deep-water penaeid shrimp Metapenaeopsis andamanensis (Wood-Mason in Wood-Mason and Alcock, 1891) from southwestern India

The present study delves into the reproductive characteristics of Metapenaeopsis andamanensis, a commercially significant deep-water shrimp collected from Sakthikulangara, off Kollam, India (8°56′60.78″ N/76°32′34.27″ E) during September 2019 to May 2022. Despite its economic importance, the reproductive traits of this species remain elusive. This research comprehensively examines macroscopic and microscopic features associated with gonadal maturity stages, including determination of size at first maturity (CL50), gonadosomatic index, and fecundity of M. andamanensis. Male-to-female sex ratio was noted as 1:1.03 using chi-square analysis. The smallest mature individuals were observed at 12 mm and 16 mm carapace length for males and females, respectively. Macroscopic observation categorized females into five groups based on gonadal coloration, while microscopic examination identified seven stages using histological characteristics. Notably, the absence of cortical crypts in the periphery of oocyte cytoplasm, a characteristic feature of the genus Metapenaeopsis, was observed in this species. Males were classified into two categories based on macroscopic and microscopic observation. The gonadosomatic index ranged from 4.25 to 10.13 for mature female individuals, exhibiting a significant increase until stage IV. Continuous spawning was observed, with a peak in May and November. The size at first maturity for females and males was determined as carapace length (CL) 23.05 mm and 17.53 mm, respectively. The average absolute fecundity was calculated as 53,889 with an average relative fecundity of 9934 oocytes. This investigation contributes valuable insights into the reproductive traits of the deep-water penaeid shrimp M. andamanensis, facilitating the development of effective management strategies for sustainable fisheries.