Infestation by Octolasmis species (Lepadiformes, Poecilasmatidae) of the marine crab Lupocycloporus gracilimanus (Decapoda, Portunidae) from India

The portunid crab Lupocycloporus gracilimanus from Digha, Bay of Bengal, India was investigated for an infestation by the lepadomorph cirriped Octolasmis spp. About 93% of the epibionts examined were found attached to the surface of the carapace, abdomen and legs, and these were identified as Octolasmis warwicki (EOW). Only 7% of the epibionts were attached to the branchial lamellae, and these were identified as Octolasmis angulata (EOA). Twenty-seven O. warwicki were also found to have conspecific dwarf males (CDM) attached to the scutum: probably an adaptive strategy to maximize the total insemination. Both the epibionts and the CDM showed spatial preference for the posterior mesobranchial region of the carapace. Most of the CDM (27%) were seen as a single attachment on the epibiont. The distance between the epibiont and its nearest neighbour (DNN) was found to be strongly and negatively correlated (, ) with the number of epibionts, indicating its preference to stay in an intermediate-sized group rather than remain solitary, which probably would have facilitated the evolution of dwarf males (CDMs). A higher percentage of epibionts were observed to have attached CDMs when the DNN increased, and above the 25 mm DNN, all epibionts were having CDM attachments, which is believed to be a strategy to maximize the fertilization success of CDMs by reducing sperm competition. A strong, positive correlation (, ) was observed between the carapace width of the host crab and the numbers of the infesting epibionts, proving that the larger crabs are more susceptible to the infestation compared to the smaller ones. The sex ratio of the host crab was 1 : 5.5 (Male : Female), nevertheless, only the females were infested by the epibionts. The percentage of the prevalence, relative abundance and mean intensity of EOW infestation were recorded as 46.15%, 182.05% and 394.44%, respectively. None of the crabs had serious external or internal infestations that seemed to hinder the activities of the animal. This is the first report of the infestation of these Octolasmis species on the portunid crab Lupocycloporus gracilimanus from India.

Feeding ecology of portunid crab, Carcinus aestuarii Nardo, 1847 in Çardak Lagoon (The Turkish Straits System)

The aim of the present study was to determine the feeding ecology of portunid crab, Carcinus aestuarii in Çardak Lagoon. For this purpose, a total of 533 crab stomachs were analyzed. Stomach contents were examined under a binocular stereomicroscope and 240 (45%) of the stomach samples were recorded as full (containing at least one food item) and 293 (55%) were recorded as empty. The occupancy rates were 25% in 127 stomachs, 50% in 69, and 100% of 44. The main diet of crab individuals was composed of fragments of fish species. Diatoms were the least consumed food by crabs. A total of 8494 diet fragments were found in the stomachs. Total stomach content was 26.39 g of fish vertebrates having the highest weight (3.58 g).

Cycloachelous levigatus sp. nov., a new swimming crab (Crustacea: Decapoda: Portunidae) from the South China Sea

A new species of portunid crab from the genus Cycloachelous Ward, 1942 is described from Vietnamese waters. Cycloachelous levigatus sp. nov. is morphologically most similar to C. orbitosinus (Rathbun, 1911), which was originally described from the syntype series collected from Western Pacific area (Cargados Carajos Islands, Amirante Islands, Seychelles) and C. octodentatus (Gordon, 1938) described from one single male from Singapore. There are differences in the sternal segments, third maxilliped, chela, abdomen and male gonopode shapes. The specific status of C. levigatus sp. nov. is also clearly supported by molecular data. Aside from a comparison of this new species with other known congeners, new photographs of syntypes of C. orbitosinus and the holotype of C. octodentatus are also provided.

Four years on the track of Callinectes sapidus (Rathbun, 1986): reconstructing the invasion of the Iberian Peninsula using social networks sites and citizen science.

Callinectes sapidus (Rathbun, 1896) is one of the 100 worst alien invasive species in the Mediterranean Sea, first reported in Venice in 1949. Firstly, the portunid crab colonized the Northern Levantine basin, and half a century later the species spreads rapidly in the Western basin. The general use of social network sites and smart phones have derived in the bloom of citizen science, which enlists the general public in gathering scientific information across large spatio-temporal scales. This research, describes the use of citizen science to unveil the colonization of C. sapidus in the Iberian Peninsula, using the Local Ecological Knowledge of recreational fishermen. Overall, C. sapidus has been detected in more than 300 locations, including a number of Natura2000 areas and 18 rivers. Eventually, recreational fishermen perceived the presence of the portunid crab as detrimental for the ecosystem.

Cancrion khanhensis sp. nov. (Crustacea: Isopoda: Entoniscidae) infesting Monomia haanii (Stimpson, 1858) (Crustacea: Brachyura: Portunidae) from Nha Trang Bay, Khanh Hoa, Vietnam, with remarks on larval stages of entoniscids and description of a new family, genus and two new species of hyperparasites infesting entoniscids

An undescribed entoniscid isopod was found to parasitize Monomia haani, a common portunid crab in Khanh Hoa province of Vietnam. The new species is the eighth in the genus Cancrion, the second species of Cancrion found parasitizing hosts in the family Portunidae, and the first member of the family Entoniscidae to be described from southeast Asia. The cryptoniscius larva of a species of Cancrion is described for the first time. The new entoniscid infests hosts with a prevalence of 10.1% and intensity of 1 or 2 females per host. A new family, genus and species of cryptoniscoid hyperparasite with novel female and cryptoniscus body morphology is also described; this is the first record of a hyperparasite found infesting an entoniscid isopod. The purported cryptoniscus larva of Tiarinion texopallium Shields & Ward, 1998 is shown to be that of a hyperparasitic cryptoniscoid isopod closely allied to the new Vietnamese hyperparasite and is described as a new species belonging to the new family and genus.

Population structure, growth and reproduction characteristics of the portunid crab, Carcinus aestuarii Nardo, 1847 (Decapoda, Carcinidae) in Çardak Lagoon, Turkish Straits System

The aim of the present study was to determine the population structure and bioecological characteristics of the portunid crab, Carcinus aestuarii in Çardak Lagoon. In this study, the crabs were sampled by means of fyke-nets at 6 different stations between April 2015 and March 2016. A total of 2458 individuals (686 females, 1755 males, and 17 juveniles) were captured. The average carapace length was measured as 38.85 ± 0.17 mm in females, and 47.65 ± 0.16 mm in males. The highest number of specimens was observed in November with 239 individuals, while the lowest number (125 specimens) was observed in February. The reproductive period in both sexes was between November and February and females with eggs were found in November, February and March. An average number of eggs in a female was 61 390 ± 8.48 and the egg diameter was 345 μm. The female : male ratio was 0.39 : 1. This paper includes the first published data on population structure, growth, and reproduction characteristics of C. aestuarii in a protected lagoon in the Turkish Straits System.

Predicting the distribution of a portunid crab in Patagonian coastal waters

Ovalipes trimaculatus is a commercially important, cosmopolitan portunid crab. However, environmental conditions that drive its distribution have never been studied. Thus, we aimed to assess the habitat preferences of this species in northern Patagonia by developing a species distribution model. We obtained spatial quantitative data of the crab and its prey species from a benthic survey performed prior to commercial fishing in the area. We used measurements of environmental condition, biomass, richness and evenness of its prey as predictors, and modeled the density of O. trimaculatus through a delta-gamma model, and produced a map of its predicted biomass. Prey biomass, depth and substrate type were the most important variables for predicting the distribution of O. trimaculatus. The model predicts a restricted depth range, with maximum crab density at 10 m (the shallowest depth sampled) in bottom substrates of relatively fine granulometry, such as silty sand and silt. Prey biomass does not determine crab presence, but, where the crab is present, higher prey biomass correlates with higher crab abundance. Our results accurately predicted 1 of the 2 actual fishing grounds; hence, the model may be a useful tool for local fishers and managers.