Description of a new species of Parasesarma (Crustacea; Decapoda; Brachyura; Sesarmidae) from the Persian Gulf, based on morphological and genetic characteristics

The genera Parasesarma and Perisesarma are common inhabitants of mangroves and estuaries of the Indo-West Pacific. These, overall similar, genera of sesarmid crabs can be told apart by the presence or absence of an anterolateral tooth, but recent and ongoing studies show that they are not reciprocally monophyletic. In recent years, detailed morphological studies have revealed a surprising number of undescribed new species within these genera. In the present paper, we describe a new species of the genus Parasesarma from the relatively poorly studied Persian Gulf. So far, these specimens had been referred to as Parasesarma plicatum (Latreille, 1803), but morphological and genetic characteristics clearly allow separation of the two species. Consequently, the species from the Persian Gulf is here described as new and morphological and mitochondrial genetic characters are provided that allow recognition of the species.     

Larval development of Brachynotus gemmellari (Rizza, 1839) (Brachyura, Grapsidae) reared under laboratory conditions

The complete larval development of the grapsid crab Brachynorusgemmellari (Rizza, 1839) was obtained by culture in the Iabomtoiy.Five zoeal stages, the megalopa and the first crab stage aredescribed and illustrated. Larval development from hatchingto first crab took 26 days at 20C. The morphological charaeiarsof the larvae of B.gemmellari are compared with those of otherknown larvae of the genus Brachynosus.     

Post‐Contest Stridulation Used Exclusively as a Victory Display in Mangrove Crabs

Victory or triumph display is a post‐contest signal, performed only by winners and not by losers. While much is unknown about its function, there is mounting evidence that victory displays are widespread among animals. However, evidence remains anecdotal in crabs. Sesarmid crabs belonging to the genera Parasesarma and Perisesarma are known to have characteristic stridulatory structures on their chelipeds. In Perisesarma eumolpe, a mangrove crab, stridulation has been anecdotally purported as a triumph display. We examined whether stridulation in P. eumolpe is a victory display and the factors affecting it by staging 17 contest trials among males and investigating the factors influencing stridulations and fight outcome in 55 fights. Using generalised linear mixed‐effects models, we find that stridulations were generally performed by winners and after fights, especially when the fights were intense. In addition, stridulation was only observed in the context of a contest, never before or outside of it. Stridulation in P. eumolpe is likely a victory display, and, unlike other forms of victory display described for other species, it appears exclusively used for asserting victory.     

The zoeal stages and megalopa of Portunus rubromarginatus (Lanchester) (Decapoda: Portnnidae), reared in the laboratory

The present state of knowledge concerning Portunus larvae isreviewed, and the three zoeal and the megalopa stages of P.rubromarginatus are described and figured. Details of appendagesetation are tabulated. This species is unusual amongst knownPortunus spp. in having only three zoeal stages and, like otherPortunus spp. but in contrast with other Portuninae, it has4 + 4, or 4 + 1 + 4, setae on the posterior telson border. When compared with larvae of the five other Indo-West PacificPortunus species whose larvae are known P. rubromarginatus zoeaeare readily distinguished from all, except P. hastatoides, usingthe key features given by Kurata (1975). Comparison was madebetween first zoeae of these two species, and also of P. pelagicusand P. sanguinolentus, using larvae reared by the authors. Itwas found telson characters alone allow distinction betweenlarvae of these four species. These characters are tabulated. P. rubromarginatus megalopae differ from those known for congenitorsin having a large spine on the uchium of the first pereiopod,but not on the carpus, and in having relatively very small sternalcornuae. Several of these features disagree with those previously thoughtto characterise larval Portuninae or Portunus species.     

Occurrence of additional Zoea-VI larvae in the mud crab, Scylla paramamosain (Estampador), reared in the laboratory

Mud crabs, Scylla spp. , are commercially important in many Indo-Pacific countries. The larval development of mud crabs has been reported previously as five zoeal and one megalopal stages. This paper reports larval rearing experiments that revealed variability in larval developmental stages in the mud crab Scylla paramamosain, one of four mud crab species. In addition to normal five zoeal stages, an alternative pathway of developing through six zoeal stages was observed for the crab. There were evidences suggested that the appearance of the additional Zoea-VI larvae was associated with unfavourable dietary conditions, including poor quality of diet, inadequate quantity of dietary supply and a period of starvation for newly hatched larvae. Based on exuviae and larval specimens, the morphology of the additional Zoea-VI larvae was described.     

Descriptions of some planktonic larvae of the Calappidae (Crustacea: Decapoda; Brachyura)

Some unidentified planktonic larval stages have been assignedto the Calappidae using Rice's key of Brachyura families. Zoeastage I from the eastern region of the Algerian coast (westernMediterranean Sea) has been attributed, according to Manningand Holthuis (1980), to Calappa granulata (L.), the only recordedrepresentative of the family from the Mediterranean Sea. Zoealstages 1-lV from the Jordanian coast of the Gulf of Aqaba, NorthernRed Sea, have been reported to the subfamily Matutinae. Comparisonsof larvae of Calappa and of Hepatus and then, of larvae of Hepatusand of Matuta, show that Hepatus larvae are more closely relatedto those of Calappa, while those of Matuta are clearly distinct.It s suggested to place the genus Hepatus with the Calappinae.Guinot (1966. 1978) placed some genera, including Hepatus. ina 'unit parthenoxystomienne, lea Aethrinae'. Larval developmentis unknown for Aethra, Actaeomorpha. Hepatella andOsachila.However, comparison of Hepatus larvae with those of Parthenopidaeshows that larval characters, particularly the setation of theendopod of the first maxilliped, are not conclusive for supportingsuch a regrouping. Moreover, the Calappidae have a combinationof primitive and advanced features which suggest that theirgrouping in the Oxystomata seems more likely to be an adaptationto a similar way of life. The morphotypal taxon Oxystornatahas been definitively rejected by Guinot (1978).     

Distribution and abundance of larvae of palaemonid prawns in the ria de Vigo, N.W. Spain

The distribution of the larval stages of the members of thePalaemonid family present in the ria dc Vigo in N.W. Spain isstudied. The highest abundance of larvae of all species occursin August, the most abundant being Palaemon adspersus and P.serratus. The larvae of these species are found mainly in thetop 0.5 m of water in straits or inlets of the ria.     

Larval stages of Brachynotus atlanticus Forest, 1957 (Crustacea: Decapoda: Grapsidae) reared under laboratory conditions

The complete larval development of the Eastern Atlantic grapsidcrab, Brachynotus atlanticus, was obtained in the laboratory.Five zoeal stages, the megalopa and the first crab stage aredescribed and illustrated. Under laboratory conditions at 23°Cthe first crab appeared on the 25th day. This is the first speciesof the genus for which the complete larval development is known.Larval features are compared with those of other members ofthe subfamily Varuninae.     

The influence of insect juvenile hormone agonists on metamorphosis and reproduction in estuarine crustaceans

Comparative developmental and reproductive studies were performedon several species of estuarine crustaceans in response to threejuvenile hormone agonists (pyriproxyfen, methoprene and fenoxycarb).Larval development of the grass shrimp, Palaemonetes pugio,was greater than two orders of magnitude more sensitive to disruptionby methoprene and fenoxycarb than was embryonic development.Developing larvae of the mud crab, Rhithropanopeus harrisii,exhibited reduced metamorphic success at lower concentrationsof methoprene and pyriproxyfen than grass shrimp larvae. Theseresponses suggest that the more rigidly controlled metamorphicprocess in crabs is more sensitive to compounds acting as endocrinedisruptors than is the more flexible metamorphic pattern inshrimp. The final crab larval stage, the megalopa, was moresensitive to methoprene and fenoxycarb exposure than earlierzoeal stages. Mud crab larvae exposed to fenoxycarb had reducedbiomass and lipid content, particularly triglycerides and sterols.Concentrations of fenoxycarb which reduced the reproductivecapacity in single life-cycle exposures of the estuarine mysid,Americamysis bahia, were similar to those concentrations whichinhibited metamorphosis in grass shrimp. Juvenile mysids releasedby exposed adults and reared through maturation without furtherexposure produced fewer young and had altered sex ratios (lowerpercentages of males) at lower parental-exposure concentrationsthan directly affected parental reproduction. These transgenerationalresponses may well be a product of irreversible effects duringdevelopmental exposures which become apparent following maturationand initiation of reproduction. These findings support usinga functional approach as an appropriate screening procedureto evaluate potential environmental endocrine-disrupting chemicalsin aquatic environments.     

漠甲亚科八种幼虫记述(鞘翊目：拟步甲科)

漠甲亚科Pimcliinae是一类广布于古北区的耐旱沙漠昆虫,幼虫在沙土内发育,危害 植物嫩芽和根部,经济意义较大。本文记述了采自宁夏、甘肃、内蒙古和新疆的8个种,即多毛扁漠甲、谢氏宽漠甲、泥脊漠甲^[1]、洛氏脊漠甲^[1]、光滑胖漠甲^[1]、蒙古漠王、谢氏宽漠王和大宽漠王的幼虫,并给出它们的检索表。幼虫标本保存于宁夏农学院。     

A description of larval and early juvenile development in Paralomis spinosissima (Decapoda: Anomura: Paguroidea: Lithodidae) from South Georgia waters (Southern Ocean)

The early ontogenetic stages of Paralomis spinosissima Birstein and Vinogradow, 1972, are described in detail and illustrated, with notes on morphological variability observed. Larval and early juvenile development was described to the crab I instar reared under controlled conditions of temperature and food supply. The abbreviated larval development invariably passed through two zoeal stages and the benthic megalopa stage. The larval development was completed without food supply, and food Artemia nauplii were first given after moult to the crab-I stage. Simplification and retarded development of the mouthparts are discussed as a function of lecithotrophy of these larvae and based on morphology no facultative feeding mode is suggested. Lecithotrophy in the Southern Ocean Lithodidae is discussed to be an adaptation allowing independence from seasonal food availability at high latitudes.     

The complete larval development and first juvenile of the spider crab Inachus thoracicus Roux, 1830 (Brachyura: Majidae: Inachinae)

The larval (two zoeae and megalopa) and first crab stages ofthe majid crab Inachus thoracicus Roux, 1830 are described andillustrated from laboratory-hatched material obtained from anovigerous female collected on the western Mediterranean continentalshelf. The morphology of all the stages is compared with thatof the corresponding stages of other known species of the genusInachus. The larvae of I. dorsettensis, I. phalangium and I.thoracicus are morphologically similar, and differ in some characteristicsfrom I. leptochirus.     

The synergism between hydrocarbon pollutants and UV radiation: a potential link between coastal pollution and larval mortality

Coastal, benthic invertebrates with complex life history strategies are exposed to stage- and habitat-specific selective forces. In the coastal environment, benthic adults are exposed to polycyclic aromatic hydrocarbon pollutants (PAHs) due to their proximity to human activities (shipping, urbanization, and industrialization). Benthic invertebrates produce lipid-rich eggs or larvae that absorb PAHs from polluted estuaries and coastal waters. The larvae of many coastal invertebrates move offshore following release from benthic adults. During development in offshore waters, larvae of some species are exposed to relatively high levels of ultraviolet (UV) radiation. Marine organisms vary in their tolerance to PAHs and UV radiation. The purpose of this study was to examine the effects of the sequential exposure of the larvae of marine crabs to PAHs and UV radiation.Using laboratory experiments, the larvae of four crab species were exposed to PAHs and UV radiation. There was a significant synergistic effect of exposure to PAH (fluoranthene or pyrene) and UV radiation on larvae of the spider crab (Libinia dubia), the stone crab (Menippe adina) and the mud crab (Panopeus herbstii). Larvae of blue crabs (Callinectes sapidus) were exposed to PAHs and UV radiation in both laboratory and solar UV experiments. Significantly higher mortality occurred for C. sapidus larvae using either type of UV-artificial or solar.Larvae of coastal invertebrates with complex life history strategies are susceptible to the combined effects of PAHs and UV radiation. In this study, the exposure of crab larvae to PAHs and UV radiation resulted in mortality to crab larvae using laboratory and solar UV experiments. There were no effects on larval crab mortality due to PAH or UV radiation independently but mortality was as high as 100% when both factors were present.     

Effects of temporary food limitation on survival and development of brachyuran crab larvae

As a consequence of the combined effects of prey patchinessand diel or tidal vertical migrations in the water column, decapodcrustacean larvae may experience temporal or spatial variabilityin the availability of planktonic food. In a laboratory study,we evaluated effects of temporarily limited access to prey onthe larvae of three species of brachyuran crabs, Chasmagnathusgranulata, Cancer pagurus and Carcinus maenas. Stage-I zoeaewere fed ad libitum for 4 or 6 h per day (20 or 25% treatments;6 h tested in C. pagurus only), and rates of larval survivaland development were compared with those observed in continuouslyfed control groups (24 h, 100%). In C. granulata, we also testedif intraspecific variability in initial biomass of freshly hatchedlarvae originating from different broods has an influence onearly larval tolerance of food limitation. Moreover, we exposedembryos and larvae of this estuarine species to moderately decreasedsalinities to identify possible interactions of osmotic andnutritional stress. Finally, we evaluated in this species theeffect of food limitation on survival from hatching throughall larval instars to metamorphosis. In all three species, limitedaccess to prey had only weak or insignificant negative effectson survival through the Zoea-I stage. The strength of the effectsof temporary food limitation varied in C. granulata significantlyamong broods. However, no significant relationships were foundbetween initial larval biomass (C content) and either survivalor development duration. Strongly decreased survival to metamorphosiswas found when food limitation continued throughout larval development.Thus, early brachyuran crab larvae are well adapted to transitorylack of planktonic food. The capability of the Zoea-I stageof C. granulata to withstand nutritional stress also under conditionsof concomitant salinity stress allows them to exploit variousbrackish environments within estuarine gradients. However, continuedexposure to limited access to planktonic prey may exceed thenutritional flexibility of C. granulata larvae.