Macrocrustaceans associated with reefs of Phragmatopoma caudata Krøyer in Mörch, 1863 (Polychaeta: Sabellariidae) and rocky shore in the Northeastern Brazil

Ecosystem engineering species create, modify, and/or maintain the characteristics of the environment. The polychaete Phragmatopoma caudata builds large sand reefs in the intertidal region of the Brazilian coast with high structural complexity, favoring the increase of diversity and interactions among the species associated. However, there are no studies concerning the association of polychaetes with crustacean macrofauna in the northeastern Brazil ecoregion, leaving an information gap on baseline biodiversity. Our aim was to analyze the effect of P. caudata colonies (PC) on the local diversity of macrocrustaceans compared to the rocky shore (RS) microhabitat. Monthly collections were carried out in low tide from September 2015 to August 2016 on 10 × 10 m quadrants for fauna and environmental variables (temperature and salinity) samples. In each microhabitat, the capture effort was two hours by two researchers. We collected 3,390 individuals, 60% associated with the colonies of PC and 40% with the RS. The PC obtained higher Shannon diversity, Pielou evenness and species richness coupled with milder water temperature and salinity conditions (minor air exposure during tide), compared to the RS that obtained greater species dominance and more extreme abiotic conditions (major air exposure). The Porcellanidae family stood out because all its species were highly abundant and had high occurrence in the colonies. The tropical Brazil porcelain crab Pachycheles greeleyi was dominant in both microhabitats (major dominance in PC). The structural complexity in the reefs of PC promoted higher availability of niches for the species, as more shelter for the resident species and refugium for temporary species with preference for more complex microhabitats. Conservation managers should prioritize the health of these colonies and subsequent species that constitute important ecosystemic and fishery resources.

Euceramus transversilineatus (Decapoda: Porcellanidae) living in the mantle lobe of the snail Melongena patula (Gastropoda: Melongenidae) in the south eastern Gulf of California: Inference of a biological association

There are abundant reports of symbiosis wherein crustaceans live inside or on mollusks; however, there are few published records of gastropods hosting decapods. This study examines the biological association between fifteen snails (124.86 ± 19.01) from the species Pacific crown conch Melongena patula and the porcelain crab Euceramus transversilineatus. Morphometric relationships of both invertebrates, as well as some sexual characteristics of the crab were conducted. These invertebrates were sampled in the Navachiste Lagoon, in the south eastern Gulf of California, Sinaloa, Mexico. It was found 86.6% of the snails housed at least a female or a male porcelain crab (17.82 ± 3.27 mm total body length) or a pair of them (heterosexual and same sex) with a sexual proportion of 2M:1F. There were no correlations between any of the crab and snail based on their analyzed morphometric relationships. For the crab males, the measurements of both chelae presented relationships with total body length, carapace length, and abdomen width however, no significant differences were observed between the mean width and chelae length of males, females or between sexes. Of the six females collected, four were gravid. Preliminary observations indicated that the porcelain crab E. transversilineatus is a commensal endosymbiont that coexist in short-term association with M. patula. Their population distribution suggests that E. transversilineatus are polygamous with a promiscuous mating pattern.

A new species of the genus Parioninella (Epicaridea, Bopyridae, Pseudioninae) from Australia

Two new records of the rare parasitic isopod genus Parioninella are described. Parioninella liuruiyui n. sp. represents the first record of the genus from Australia and the first bopyrid described from the porcelain crab Pachycheles pisoides (Heller, 1865). The female of the new species differs from other described species in lacking eyes, produced into pair of anterolateral flaps, the brood pouch completely covered by oostegites, while the male lacks pigmentation. Parioninella astridae Nierstrasz & Brender à Brandis, 1930 is recorded from Mindoro, Philippines, in Pachycheles sculptus (H. Milne Edwards, 1837). An identification key to the three Parioninella species is provided.

A new species of the porcelain crab genus Petrolisthes from the Pacific coast of Panama, with taxonomic notes on closely related species (Decapoda: Anomura: Porcellanidae)

A new species of porcelain crab, Petrolisthes lazarus sp. nov., is described from the Pacific coast of Panama, based on two female specimens. The new species is morphologically most similar to another eastern Pacific species, P. crenulatus Lockington, 1878, especially in the general configuration of the carapace, chelipeds and ambulatory legs. However, P. lazarus sp. nov. can be separated from P. crenulatus by the differences in the proportions of the carapace, the shape of the frontal region of the carapace, and the setation pattern of the cheliped. In addition, P. lazarus sp. nov. and P. crenulatus appear to be allopatric, the latter species presently being known only from Mexico. Among other eastern Pacific taxa, P. lazarus sp. nov. may have some affinities with P. ortmanni Nobili, 1901 and P. lewisi (Glassell, 1936), from which it can be easily distinguished by the chelipeds lacking a dense field of setae on the outer (lateral) surface of the palm and with different proportions of some articles, especially the carpus. The four species can also be distinguished from each other by their diagnostic, although somewhat variable colour patterns.

Multiple paternity in the intertidal zone porcelain crab Petrolisthes cinctipes Randall, 1840 (Decapoda: Anomura: Porcellanidae) is a life-history strategy that increases fitness during heat stress

Multiple paternity is widespread across animal and plant taxa and can increase genetic diversity and enhance fitness, especially in unpredictable environments. A prior study of the intertidal zone porcelain crab, Petrolisthes cinctipes (Randall, 1840), found that most females carried polyandrous broods. We tested the hypothesis that multiple paternity in P. cinctipes enhances fitness through increased average brood tolerance to temperature stress. Embryonic survival of split broods (N = 27) was measured under ambient conditions and following a single one-hour heat shock at 30 °C. Two microsatellite loci were used to genotype embryos and mothers in order to distinguish multiple from single paternity in each brood. Mean overall hatching percentage did not differ between singly and multiply sired broods; however, when exposed to a heat-shock, single-sired broods experienced 11% lower hatching success. Though relative fitness was higher in single-sired broods under non-stressful conditions, extrapolation of our results to conditions where temperatures are at least 30 °C (present-day extremes for the California coast) for > 2 days of the embryonic brood period, multiply sired broods have a relative fitness that is approximately 24 times higher after 15 generations. Maternal quality (size) and the timing of the heat shock relative to developmental timing also influence the brood response to heat shock. Our results suggest that multiple paternity reduces embryo survival variance between ambient and heat-shock conditions and that polyandrous behavior could be an advantage for P. cinctipes in the thermally variable high-intertidal zone. We conclude that multiple paternity is an important strategy for increasing fitness by genetic diversification in organisms that experience severe and unpredictable levels of environmental stress.

Application of Morphological Analysis and DNA Barcode in Determination of The Porcelain Crab Species (Pisidia sp.) from The Tunda Island, Banten

The phenomenon of marine cryptic species is frequently found in altered ecosystem such as dead corals habitat. Dead corals as habitat can be used by marine fauna like crustacean from family of porcellanidae. This study was aimed to identify and clarify the species of porcelain crab from Tundai sland, Banten province by applying the morphological analysis and DNA barcoding technique. The result of morphological analysis showed that decapod samples were crabs of the genus Pisidia, family of Porcellanidae with specific morphological characteristics were the ratio of carapace size is longer than tbroad, have long antennae which can be moved, serrated anterior rostrum, chelae rather flattish and unequal size of arms. While based on molecular barcode analysis by using COI, samples were identified as Anomura sp. with 94% of similarities. The difference of the result was suspected due to the lack of suitable genetic data on genbank.

A new species of the Polyonyx sinensis group (Crustacea: Decapoda: Anomura: Porcellanidae) from the Central Philippines

A new species of porcelain crab, Polyonyx angustus n. sp., is described on the basis of material collected from Panglao Island, the Central Philippines. It is morphologically allied to P. boucheti Osawa, 2007, P. pilosibrachium Osawa, Naruse & Ng, 2018, and P. utinomii Miyake, 1943, but distinguished by the shape of the carapace and rostrum. Re-examination of the specimens from the Maldives previously referred to P. utinomii has showed that they belong to the new species instead. The present knowledge suggests that P. utinomii is distributed only in the Japanese main islands from central Honshu to Kyushu.