Fecundity, embryo size and embryo loss in the estuarine shrimp Salmoneus carvachoi Anker, 2007 (Crustacea: Alpheidae) from a tidal mudflat in northeastern Brazil

Studies on fecundity and embryo size have been frequently used to infer about the reproductive potential, embryogenesis, and the energy investment in embryo production in crustaceans. These parameters are relevant to the knowledge of life-history and diversity of reproductive strategies developed by this group. This study addressed the embryo production by the estuarine shrimp Salmoneus carvachoiAnker, 2007, a poorly known caridean shrimp. We investigated whether there was (1) a correlation between fecundity and carapace length, (2) an increase in embryo volume along the embryonic development, and (3) loss of embryos along development. In addition, we investigated whether the esternite length and height and width of the pleura of the second abdominal somite were good predictors of fecundity. A total of 53 embryo-carrying individuals were collected in December 2016 and February 2017 in a tidal mudflat from the estuary of the Paripe River, Ilha de Itamaracá, Pernambuco, Brazil. The carapace length ranged from 3.23 to 4.64 mm (3.78 ± 0.26 mm). Among those, 25 individuals had embryos in initial stage, 5 in intermediate stage and 15 in final stage. Fecundity ranged from 14 to 67 (33.65 ± 12.51 embryos) and was weakly correlated with carapace length. However, fecundity was strongly correlated with the width of the second sternite and width of the pleura of the second abdominal somite. Embryo volume increased markedly (93%) from the initial to the final stage of development. This increase might be due to water uptake to facilitate the membrane rupture at the onset of larvae hatching. There was significant loss of embryos only between the initial and intermediate stage. Future studies on the embryo production by other species of Salmoneus Holthuis, 1955 are necessary to understand and compare these aspects of reproductive biology.

Fecundity, embryo size and embryo loss in the estuarine shrimp Salmoneus carvachoi Anker, 2007 (Crustacea: Alpheidae) from a tidal mudflat in northeastern Brazil

Studies on fecundity and embryo size have been frequently used to infer about the reproductive potential, embryogenesis, and the energy investment in embryo production in crustaceans. These parameters are relevant to the knowledge of life-history and diversity of reproductive strategies developed by this group. This study addressed the embryo production by the estuarine shrimp Salmoneus carvachoiAnker, 2007, a poorly known caridean shrimp. We investigated whether there was (1) a correlation between fecundity and carapace length, (2) an increase in embryo volume along the embryonic development, and (3) loss of embryos along development. In addition, we investigated whether the esternite length and height and width of the pleura of the second abdominal somite were good predictors of fecundity. A total of 53 embryo-carrying individuals were collected in December 2016 and February 2017 in a tidal mudflat from the estuary of the Paripe River, Ilha de Itamaracá, Pernambuco, Brazil. The carapace length ranged from 3.23 to 4.64 mm (3.78 ± 0.26 mm). Among those, 25 individuals had embryos in initial stage, 5 in intermediate stage and 15 in final stage. Fecundity ranged from 14 to 67 (33.65 ± 12.51 embryos) and was weakly correlated with carapace length. However, fecundity was strongly correlated with the width of the second sternite and width of the pleura of the second abdominal somite. Embryo volume increased markedly (93%) from the initial to the final stage of development. This increase might be due to water uptake to facilitate the membrane rupture at the onset of larvae hatching. There was significant loss of embryos only between the initial and intermediate stage. Future studies on the embryo production by other species of Salmoneus Holthuis, 1955 are necessary to understand and compare these aspects of reproductive biology.(AU)

Description of the first juvenile stage of the fiddler crab Minuca mordax (Smith, 1870) (Crustacea, Decapoda, Ocypodidae)

The first stage of the fiddler crab Minuca mordax is described here. Zoea larvae obtained from four ovigerous female were reared in the laboratory until the development of the first crab stage. The development from zoea I to the first juvenile instar lasted 35 days after hatching. The first crab stage of Minuca mordax can be morphologically distinguished from those of Minuca burgersi and Leptuca cumulanta by a 2segmented antennule endopod (3segmented in M. burgersi, unsegmented in L. cumulanta), an unsegmented maxillule endopod (2segmented in M. burgersi and L. cumulanta), and a 4segmented first and second maxilliped endopod (respectively unsegmented and 5segmented in M. burgersi and L. cumulanta). The three species have the following characters in common: segmented peduncle of antennule 2; endopod of antennule unsegmented; presence of aesthetascs on the antennule; peduncle of antenna 3segmented; flagellum of antenna 6segmented; mandible 3segmented; maxilla with coxal and basal endite bilobed; first, second and third maxillae with exopod 2segmented and abdomen with six somites that are wider than long.

O primeiro estágio juvenil do caranguejo chama-maré Minuca mordax foi descrito. Larvas zoea foram obtidas de fêmeas ovígeras e cultivadas em laboratório até atingir o primeiro estágio juvenil. O desenvolvimento de zoea I até o primeiro estágio juvenil teve duração de 35 dias após a eclosão. O cultivo foi mantido em um aquário com salinidade 20‰, sob fotoperíodo (claro: escuro/12:12) e temperatura (25°C) constante. Os juvenis foram dissecados e os apêndices desenhados e descritos. O primeiro estágio juvenil de M. mordax pode ser morfologicamente distinto do mesmo estágio de M. burgersi and L. cumulanta por apresentar antênula com endopodito bisegmentado (3-segmentos em M. burgersi, não segmentado em L. cumulanta), maxílula com endopodito não segmentado (2-segmentos em M. burgersi e L. cumulanta), e primeiro e segundo maxilípodo com endopodito 4-segmentado (respectivamente não segmentado e 5-segmentos em M. burgersi e L. cumulanta). Os seguintes caracteres são comuns a estas três espécies: pedúnculo da antênula bissegmentado; antênula com endopodito não segmentado; presença de estetascos na antênula; pedúnculo da antena trisegmentado; flagelo da antena 6-segmentado; mandíbula trisegmentada; maxila com coxal e basal endito bilobado; primeira, segunda e terceira maxila com exopodito bissegmentado e abdômen com seis somitos que são mais largos do que longos.

Description of the first juvenile stage of the fiddler crab Minuca mordax (Smith, 1870) (Crustacea, Decapoda, Ocypodidae)

The first stage of the fiddler crab Minuca mordax is described here. Zoea larvae obtained from four ovigerous female were reared in the laboratory until the development of the first crab stage. The development from zoea I to the first juvenile instar lasted 35 days after hatching. The first crab stage of Minuca mordax can be morphologically distinguished from those of Minuca burgersi and Leptuca cumulanta by a 2segmented antennule endopod (3segmented in M. burgersi, unsegmented in L. cumulanta), an unsegmented maxillule endopod (2segmented in M. burgersi and L. cumulanta), and a 4segmented first and second maxilliped endopod (respectively unsegmented and 5segmented in M. burgersi and L. cumulanta). The three species have the following characters in common: segmented peduncle of antennule 2; endopod of antennule unsegmented; presence of aesthetascs on the antennule; peduncle of antenna 3segmented; flagellum of antenna 6segmented; mandible 3segmented; maxilla with coxal and basal endite bilobed; first, second and third maxillae with exopod 2segmented and abdomen with six somites that are wider than long.(AU)

O primeiro estágio juvenil do caranguejo chama-maré Minuca mordax foi descrito. Larvas zoea foram obtidas de fêmeas ovígeras e cultivadas em laboratório até atingir o primeiro estágio juvenil. O desenvolvimento de zoea I até o primeiro estágio juvenil teve duração de 35 dias após a eclosão. O cultivo foi mantido em um aquário com salinidade 20‰, sob fotoperíodo (claro: escuro/12:12) e temperatura (25°C) constante. Os juvenis foram dissecados e os apêndices desenhados e descritos. O primeiro estágio juvenil de M. mordax pode ser morfologicamente distinto do mesmo estágio de M. burgersi and L. cumulanta por apresentar antênula com endopodito bisegmentado (3-segmentos em M. burgersi, não segmentado em L. cumulanta), maxílula com endopodito não segmentado (2-segmentos em M. burgersi e L. cumulanta), e primeiro e segundo maxilípodo com endopodito 4-segmentado (respectivamente não segmentado e 5-segmentos em M. burgersi e L. cumulanta). Os seguintes caracteres são comuns a estas três espécies: pedúnculo da antênula bissegmentado; antênula com endopodito não segmentado; presença de estetascos na antênula; pedúnculo da antena trisegmentado; flagelo da antena 6-segmentado; mandíbula trisegmentada; maxila com coxal e basal endito bilobado; primeira, segunda e terceira maxila com exopodito bissegmentado e abdômen com seis somitos que são mais largos do que longos.(AU)