Currently, 14 of the 50 species of Lysmata are known to possess a long accessory branch with more than two articles. Historically, Lysmata intermedia and Lysmata moorei were the only two ‘long-branch’ species inhabiting the southwestern Atlantic. Here we describe, based on morphological, molecular and colour pattern data, a new species of Lysmata possessing a long accessory branch from Pernambuco, northeastern Brazil. Our maximum-likelihood analysis recovered Lysmata elisa sp. n. as a sister species to Lysmata jundalini. Both species are closely related to Lysmata holthuisi and L. intermedia. The four aforementioned species comprise the L. intermedia species complex. The new species may be morphologically distinguished from the other closely related species by different sets of characters, which include details of the dorsolateral antennular flagellum, armature of ischium of the second pair of pereiopods, intraorbital process shape and relative proportions of pereiopods. Our results reinforce the importance of refining biodiversity data through the application of integrative taxonomic approaches to expand the knowledge of local and global biodiversity. The biodiversity of Lysmata deserves special attention, as they are intensively exploited in the aquarium trade.

The peacock-tail shrimp Ancylocaris brevicarpalis Schenkel, 1902, is an obligate symbiont of sea anemones and well known for its remarkable colouration. Yet, very little information is available about its population structure and life-history traits, including reproductive parameters (fecundity, embryo volume and reproductive output). A total of 574 individuals were collected from the Gulf of Mannar, Tamil Nadu, India between February 2017 and July 2018, out of which 214 were males (37.28%), 355 were females (61.84%), and 5 (0.87%) juveniles. The highest percentage of individuals were observed in the post-monsoon season (38.10%) followed by monsoon (34.85%), pre-monsoon (15.02%), and summer seasons (12.01%). The overall sex ratio was skewed towards female individuals (0.55 male: 1 female). Fecundity was higher in females carrying early-stage embryos and embryo volume did increase, but not statistically significantly from early to late stages. The reproductive output was negatively allometric to the mean female body weight. The present study provides first-of-its-kind information on the population as well as individual-level reproductive characteristics of A. brevicarpalis.

The common prawn (Palaemon serratus) supports a small-scale but economically important seasonal static-gear fishery in Cardigan Bay, Wales (UK). Due to a lack of statutory obligation and scientific evidence, the fishery has operated to date without any harvest-control rules that afford protection from overfishing. In response to fluctuations in landings and in pursuit of increased economic returns for their catch, some members of the fishing industry have adopted a size-selective harvesting regime, which we evaluate here using baseline data. Monthly samples were obtained from fishers operating out of five ports between October 2013 and May 2015 (N = 4233). All prawn were sexed, weighed and measured, whilst the fecundity of females was estimated for 273 (44%) individuals. Peak spawning occurred during the spring and females were estimated to undergo a ‘puberty moult’ at a carapace length (CL) of 7.7 mm, whilst functional maturity was estimated at a CL of 9.9 mm. The sampled population exhibited sexual dimorphism, with females attaining a greater size than males. The current harvesting regime results in a sex bias in landings as even large mature males remained under the recruitment size to the fishery, unlike the large mature females. The temporal trend in sex-ratio indicates a continual decrease in the catchability of female prawn through the fishing season; however, whether this is caused by depletion via fishing mortality or migratory behaviour is yet to be resolved. Here, we provide a comprehensive baseline evaluation of population biology and discuss the implications of our findings for fisheries management.

The present study tests hypotheses about sexual dimorphism in body size and morphology versus differential mating behaviours of three male ontogenetic stages (typus, intermedius and robustus morphotypes) of the hingebeak shrimp Rhynchocinetes durbanensis Gordon using canonical discriminant analysis. There is strong sexual dimorphism in this species, in that robustus morphotypes are greater in size and with larger appendages (extended third maxillipeds and major [first] chelipeds) than females. As typus males grow bigger in size, their third maxillipeds and major chelipeds become proportionately larger than those of females, and the numbers of corneous spines on the terminal segment of the maxillipeds are reduced. Although there is no sexual dimorphism in body size between typus and intermedius males and females, the robustus males are often substantially larger than females. During mating and spermatophore transfer, all male morphotypes performed similar behaviours (touching, overlapping and holding), but only intermedius and robustus morphotypes appeared to fertilize the broods of the females successfully. Robustus males were faster in approaching as well as mating with receptive females than subordinate males. When mating with robustus males, females spawned more quickly than after mating with typus and intermedius males. Additionally, the time taken for spermatophore transfer by typus males was longer. Rejection by females during the initial approach by typus males often resulted in unsuccessful spermatophore attachment. Results of this study suggest a dominance hierarchy in R. durbanensis similar to certain other rhynchocinetid species in which females appear to prefer mating with the larger robustus males.

We report for the first time the association of some caridean shrimps with the octocoral Carijoa riisei (Cnidaria: Clavulariidae) and the sponge Dragmacidon reticulatum (Porifera: Axinellidae), in estuaries from north-eastern Brazil. The alpheid shrimp Synalpheus apioceros, Synalpheus fritzmuelleri, Alpheus formosus, Alpheus carlae and the palaemonid Cuapetes americanus are reported in association with Carijoa riisei. The latter two species, plus the alpheid Alpheus buckupi, are recorded in association with D. reticulatum.

The caridean shrimp Bathypalaemonella serratipalma was photographed by a remotely operated vehicle at 1120–2223 m in the northern Gulf of Mexico. The shrimp was living on previously unreported host cnidarians of the families Isididae and Alcyoniidae, and a black coral (Antipatharia), as well as previously reported gorgonian hosts (Chrysogorgia and Iridogorgia spp.). We did not observe interactions between B. serratipalma and other invertebrates living on these hosts, nor did the shrimp occur on the same host cnidarians as the anomurans Uroptychus nitidus or Eumunida picta.

We report the occurrence of the sponge-dwelling snapping shrimp Synalpheus dardeaui (Decapoda: Alpheidae) for the first time from Porto Seguro (Bahia, Brazil) and record an additional sponge host for the species, Ircinia cf. strobilina. Synalpheus dardeaui was previously known from Florida and some localities in the Caribbean Sea. Therefore, the present finding represents the first record of the species in the south-western Atlantic, extending its southern distribution limit by a latitude of 28° from Curaçao (12°N) to Porto Seguro (16°S). Variations between the Brazilian and Florida–Caribbean materials are discussed and illustrated.

Eight species of alpheid shrimps are reported for the first time from the coral reef systems off Mexico's northern Yucatan Peninsula (Alacranes, Madagascar and Serpiente Reefs). These species are: Alpheus immaculatus; Alpheus paraformosus; Alpheus punctatus; Parabetaeus hummelincki; Salmoneus depressus; Synalpheus chacei; Synalpheus dominicensis; and Synalpheus elizabethae. The geographical ranges of these species are extended into the southern Gulf of Mexico; most of them are recorded from Mexican territorial waters for the first time. Brief notes on their ecology and taxonomy are provided. Six species are illustrated by colour photographs.

A new species of the hippolytid shrimp genus Lebbeus White, 1847 is described from the Von Damm Vent Field (VDVF) on the Mid-Cayman Spreading Centre, Caribbean Sea, at 2294 m water depth. Lebbeus virentova sp. nov. is defined and illustrated from seven specimens, with brief notes on its distribution and habitat. Molecular phylogenetic data from the COI mDNA region are used to analyse the species’ phylogenetic position, and its morphology is compared with previously described species. This new species represents the second family of caridean shrimp to be reported from the VDVF. Lebbeus virentova sp. nov. is the eighth member of the genus to be described from hydrothermal vents and appears to be the first hippolytid shrimp at a vent field known from outside the Pacific Ocean.

Rimicaris hybisae sp. nov. is described from hydrothermal vent fields on the world's deepest seafloor spreading centre, the Mid-Cayman Spreading Centre (MCSC), Caribbean, at depths of 2300–4960 m. The new species is described and illustrated on the basis of 17 specimens. Brief notes on the distribution and habitat of the new species are provided. Molecular phylogenetic data from mitochondrial COI (460 base pair (bp)), 16S ribosomal RNA (549 bp) and nuclear 18S ribosomal RNA (576 bp) regions is used to complement the description. Morphological variation within R. hybisae sp. nov. and morphological affinities with previously described species are discussed. Based on morphological and molecular evidence, the new species is provisionally assigned to the genus Rimicaris, and differs from all known species in the genus by a distinctive pair of ‘pores' on the posterior lobes of its four-lobed dorsal organ. An emended diagnosis for Rimicaris is provided. Rimicaris hybisae sp. nov. is the first taxon to be described from MCSC vent fields. This record extends the known geographical range of Rimicaris into the Caribbean Sea and constitutes the deepest documented occurrence of alvinocaridid shrimp.

The shrimps Neopontonides chacei, Tozeuma serratum and Periclimenes iridescens, a barnacle (Conopea galeata), two species of gastropods (Ovulidae) and the oyster Pteria colymbus live on Leptogorgia spp. in the northern Gulf of Mexico. For each species and related species in the area, we give records and notes on coloration and behaviour.

Three specimens of the crangonid sand shrimp species Crangon uritai are reported from the muddy intertidal zone of Newport in Port Phillip Bay, Victoria. The discovery of the species in the bay is the first record of the genus Crangon from Australian waters and the first report of the East Asian coastal species Crangon uritai from the southern hemisphere. Its status as an introduced species is suggested and the likely vector for introduction is discussed. A key to the identification of crangonid shrimp species from Port Phillip Bay is included.

The present contribution reports on a small collection of caridean shrimps from Qatar. Six species are reported upon, three of which are new additions to the caridean fauna of the Persian Gulf, also representing the first records for the crangonid genus Philocheras and the family Pandalidae from the area. An annotated checklist of species known to date from the Persian Gulf is provided, totalling 59 species.

The rare deep-sea family Bathypalaemonellidae is known from a small number of specimens and includes two genera. The deep-sea coral reefs are important habitats that aggregate the fauna, acting as feeding and reproduction sites for many species. Bathypalaemonella texana was previously recorded only from the type locality (Gulf of Mexico). This is the second global record of this species and the first record of this rare species in the south-western Atlantic (Brazil). It was collected in a deep-sea coral reef habitat.

The symbiotic alpheid shrimp Aretopsis amabilis De Man, 1910 (Decapoda: Caridea: Alpheidae) is reported from Vietnam for the first time. A male–female pair of mature individuals of this species was found inside a large strombid shell occupied by a hermit crab Dardanus cf. lagopodes (Forskål, 1775) (Diogenidae). The live coloration of the shrimps and their host, as well as its known associations and information on the species distribution are given.

Since the discovery of the non-native prawn Palaemon macrodactylus in the Orwell estuary in December 2001, the species is now reported from other estuaries in the greater Thames area: Stour, Medway and Thames. A specimen from archived samples from the Thames is now the earliest European record (1992) but the original site and date of introduction into Europe and Britain remains unknown. Competition with the native P. longirostris is a possibility and biologists and naturalists are advised to check prawn specimens from current and archived samples collected from any British or European estuary for P. macrodactylus.

The life cycle of a brackish-water population of Palaemonetes argentinus, a normally freshwater shrimp from the warm temperateregion of eastern South America, was studied in Mar Chiquita coastal lagoon, Argentina. In 1995, recruitment took placein January, followed by two growth periods, the first at the beginning of summer and the second from the end of winter throughmost of spring. Females reached a larger size than males. Ovigerous females, probably belonging to two cohorts, were foundfrom October 1995 to February 1996, with a maximum number in November (93 %). Their average size and fecundity varied duringthe breeding period. The sex ratio did not significantly differ from 1:1 except in November. Evidence of mature oocytes inthe ovaries was found in ovigerous and postovigerous shrimps, suggesting that they breed twice a year. However, only some femalesof the first cohort produced a second hatch in 1995. The maximum number of undifferentiated embryos carried by a femalewas 250; there was a positive relationship between fecundity and size. Larvae were collected together with adults from Novemberto March. The life history is similar to that described in several freshwater populations. Differences are restricted to chronologicalaspects such as a shorter unimodal breeding period and are probably related to climatic factors, since Mar Chiquita is nearthe southern limit of the geographic range of the species. Data presented here suggest interannual variations in reproductive patternsthat lead, sometimes, to a longer bimodal breeding period.