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Abstract

This study aims to elucidate the physical evidence of the moulting stages and the characteristics of ecdysteroid levels in the moulting cycle of Neocaridina denticulata sinensis. From hatching to the first complete pleopod development, N. denticulata sinensis moults 14 times at 25°C in the laboratory. The whole process was divided into four stages based on the moulting characteristics during the various intervals. Using the structural changes of the telson and Drach’s classification system, four moulting periods (postmoult, intermoult, premoult, and ecdysis) were recognized. In addition, based on the changes of the setal lumen, internal cone, and the epidermis, the premoult period was further divided into five substages (D0, D1, D2, D3, and D4). Despite similar fluctuation patterns in mature males and females, significant differences of haemolymph ecdysteroid titers were revealed in postmoult, intermoult, and premoult. These works will provide an important additional reference for the exploration of the moulting mechanism in crustaceans.

In: Crustaceana

Abstract

The biodiversity of copepods as examined in the present study is based on an oceanographic survey conducted on two ecosystems along the Algerian coast (central and eastern) in the early autumn of 2014. During that investigation, the thermocline was present at shallow depth, extending between 30 and 80 m. A total of 49 species were recorded in the samples, belonging to 20 families, among which six families, Calanidae, Eucalanidae, Metridinidae, Oithonidae, Paracalanidae, and Temoridae, appeared to be dominant. The total abundance of zooplankton at the 13 stations was less than 600 ind/m3. Two geographic groupings have been distinguished: stations in the central sector (group 1) are in opposition to the other stations in the eastern sector (group 2). The quantitative levels of copepods are less abundant in the east (234.15 ind/m3) than in the centre (334.99 ind/m3). In the central regions, the trophic organization is dominated by omnivores (73.02%), with an inferior co-dominance of carnivores (14.02%) and herbivores (12.95%). In the east, copepods with omnivorous behaviour are strongly represented (82.14%), followed by phytophagous (13.85%) and carnivorous (4.01%) species. The distribution of the abundances over the copepod communities was found to be linked to the temperature, salinity, North Atlantic Oscillation (NAO) index, and phytoplankton biomass.

In: Crustaceana

Abstract

The species name Kovalevskiella elisabethae n. sp. is proposed for a new taxon of a Recent ostracod found in interstitial sediments of the alluvial plain of the Danube in the surroundings of Vienna, Austria. The main characters that differentiate Kovalevskiella elisabethae n. sp. from its congeners K. bulgarica, K. cvetkovi, K. dani, K. rudjakovi and K. phreaticola are based on the morphology and chaetotaxy of antennula, antenna and mandible. Important diagnostic characters of the new species are the 5-segmented antennula, the presence of 2 setae on the posterior margin of its fourth segment, the presence of only 1 seta (besides the conjoined seta and aesthetasc) on its last segment, as well as the presence of 1 seta on the basis and 3 on the endopodite of the mandibula. An identification key for the Recent species of the genus is provided.

In: Crustaceana

Abstract

The identity of the poorly known plagusiid crab Euchirograpsus polyodous (Stebbing, 1921) is clarified on the basis of a good series of specimens from Zanzibar. The species proves to be a senior synonym of Euchirograpsus madagascariensis Türkay, 1978. The species is characterized by the more elongate and rugose third maxillipeds, distinctly serrate flexor margins of the second and third ambulatory legs, presence of only five major pairs of corneous setae on the ambulatory dactylus, and structure of the male first gonopod. The holotype of Euchirograpsus madagascariensis Türkay, 1978, is here designated as the neotype of Pachygrapsus polyodous Stebbing, 1921, making both names objective synonyms. A key to the nine species of Euchirograpsus is provided.

In: Crustaceana
Author: Kunihiko Izawa

Abstract

Nothobomolochus cypseluri (Yamaguti, 1953) is redescribed based on specimens of the female recovered from the bucco-branchial cavity of an unidentified flyingfish, collected at the Owase fish market, Owase, Mie Prefecture. The possession of postantennal processes and lateral processes was verified in this species for the first time, next to these structures in N. aigo Izawa, 2022, in this genus.

In: Crustaceana

Abstract

We report morphological abnormalities for the specimens of Macrobrachium amazonicum (Heller, 1862) collected from the Amazon province in the State of Pará, Brazil, using a local trap called “matapi” at the lower Tocantins River, from June 2004 to May 2005. After sampling, the specimens were sorted out, fixed in ethanol and deposited in the carcinological collection of the Crustaceans Laboratory at the Universidade Federal Rural da Amazônia (UFRA) and the Center for Research and Management of Fishery Resources of the North Coast (CEPNOR/ICMBio). Three individuals showed morphological anomalies in the rostrum and telson. This is the first record of such morphological abnormalities for this species, but further investigation is needed to establish the cause of these anomalies in the region.

In: Crustaceana

Abstract

The intertidal crustaceans on the Chilean coast are characterized by high diversity and niche specialization. The present study applied a size-overlap null model analysis for intertidal decapod communities in a central Chilean rocky beach (El Quisco, 32°24′S). The application of six models simulations revealed that there is a size overlap, confirmed by the results of all those six simulations. This means that the reported species would share their ecological niches. The results agree with the first classical ecological descriptions for Chilean intertidal decapods at a local scale and support the observations for similar species on the southern Pacific and southern Atlantic coasts, and the results of the null model agree with a first comparative study of decapods in the north and on the central Chilean rocky coast.

In: Crustaceana

Abstract

In Mexico, shrimp catch is the main fishing activity, and the second important species is the blue shrimp, Penaeus stylirostris. Specimens of P. stylirostris collected in 2016-2018 from inland waters (bay) and offshore (littoral) in the Santa María la Reforma lagoon (SMLR) system were analysed. The sexes were separated, and then individuals were measured in total length (L, mm) and weighed (W, g). The data were transformed into a natural logarithm and were adjusted to seven candidate models with a multi-model approach (Linear, Quadratic, Cubic, Broken stick, Two segments, Three segments and Four segments: the last two proposed in this study as new equations). A total of 30 439 specimens were analysed. Statistical differences were found in L between areas (KS test, p<0.0001). Positive and negative allometry was observed according to biometric relationship and sex. The best model was selected with the lowest value of the Akaike information criterion, resulting in the choice of the Four segments model.

In: Crustaceana