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Abstract

Eurytemora represents a challenging group of species due to their taxonomy, in particular the former group of cryptic species known as E. affinis sensu lato. In this paper, we analyse DNA sequences that are all available in GenBank, along with our own data on the genus Eurytemora. For this study, a set of mitochondrial and nuclear genes (CO1, nITS and 18SrRNA) was used. In total 543 sequences were analysed (437 CO1; 54 nITS; 52 18SrRNA). However, this work is mainly meta-analytical, and only 67 sequences from unstudied earlier populations or species were obtained specifically for this work to analyse the genetic differentiation of the morphologically described species. We found that relatively young species of the E. affinis complex are different from each other in the CO1 and nITS genes, but not in the conservative 18SrRNA nuclear gene. Nucleotide differences among affinis-group species in the CO1 gene are 9.4-11.8%; in the nITS genes, 1.1-5.0%. At the same time, all other studied Eurytemora species have significant differences from each other in the CO1 and nITS genes, as well as in 18SrRNA. The level of differences among the species is 13.2-19.2% for the CO1 gene, 18.0-27.6.2% for nITS genes, and 0.4-1.8% for the 18SrRNA gene.

In: Crustaceana

Abstract

A new technique for the optimization of the taxonomic study of cephalic openings in Branchiopoda is proposed here. The study of the cephalic openings in the various taxa that constitute this clade is of great importance. This is true not only for taxonomic studies, being fundamental for species identification in the Chydoridae, but also for phylogenetic and physiological investigations. For this, currently available protocols include the use of electron microscopic analysis, using the whole specimen, or the use of optical microscopy, by removing the cephalic shield from the specimen and mounting it on slides. This work presents a simple technique for the study of cephalic openings in Branchiopoda, facilitating their study, particularly for those associated with the Chydoridae.

In: Crustaceana

Abstract

Charybdis lucifera (Fabricius, 1798), Demania reynaudii (H. Milne Edwards, 1834), Galene bispinosa (Herbst, 1783), and Neodorippe callida (Fabricius, 1798) are documented for the first time from the territorial waters of Bangladesh. Before this account, the families Dorippidae MacLeay, 1838 and Galenidae Alcock, 1898 were also unknown to the country. All specimens but Neodorippe callida were sampled from St. Martin’s Island, a sedimentary island on the continental shelf. We encountered N. callida from Dublar Char Island, a mangrove block extending into the Bay of Bengal. We collected D. reynaudii from a beach food stall, being displayed apparently unaware of the species’ toxicity, which seems not to be known in the region; the other species were sourced from artisanal seining activities. Here, taxonomic traits of these species are discussed respective to close congeners, and with necessary remarks on their locality.

In: Crustaceana

Abstract

The doublesex/mab-3 related transcription factor (Dmrt) gene family plays a conserved sexual regulatory role in different phyla, thus providing an important clue for studying the sex mechanism of crustaceans. In this study, cDNAs of three Dmrt homologs were cloned and characterized in the swimming crab, Portunus trituberculatus (Miers, 1876). Sequence analysis indicated the obtained Dmrts might be orthologs of the invertebrate Dmrt1 (iDmrt1) described in the spiny lobster, Sagmariasus verreauxi (H. Milne-Edwards, 1851). Real-time quantitative PCR revealed that the PtiDmrt1 transcripts were highly expressed in testis, muscle, Y-organ, and gill, and in the C2 stage during the developmental process. In addition, RNAi of PtiDmrt1 showed that the gene expression of insulin-like androgenic gland hormone (IAG) decreased remarkably at 24 h after injection, but increased to a higher level than in the control group at 48 h post injection. The results suggested that the PtiDmrt1 is a potential regulator of IAG, although the underlying mechanism may be complicated.

In: Crustaceana
Author: Kunihiko Izawa

Abstract

Three new and five known species of Bomolochidae Claus, 1875, parasitic on Japanese actinopterygian fishes, are (re)described. They are Bomolochus bellones Burmeister, 1835, B. decapteri Yamaguti, 1936, B. hoi sp. nov., Naricolax sphyraenae sp. nov., Nothobomolochus cypseluri (Yamaguti, 1953), Orbitacolax brevispinus Moon, Choi & Venmathi Maran, 2018, O. scombropsi sp. nov., and O. unguifer Kim & Moon, 2013. The copepodid IV female of B. bellones, the male and copepodid IV female of Na. sphyraenae, the male and copepodid IV and V female of No. cypseluri and O. unguifer are herein described. Sexual dimorphism is found in the antennule, maxilliped, and legs in the family.

In: Crustaceana

Abstract

In this study, we used the Monte Carlo model (CMSY) to estimate fisheries reference points based on annual lobster landings. During the period 2012-2018, fishing pressure on lobster stocks decreased and a tendency for recovery was observed, despite the low biomass levels of approximately 29%. In 2019, the stock size was capable of producing yields close to the maximum sustainable yield (5770 t), with a probability of 58.1%. The enforcement of management measures should be continued in order to eliminate sources of negative externalities and rebuild stocks. We also demonstrate that the closed season does in fact protect the main events of the lobster life cycle. Responsible and efficient management should focus on life cycle studies and reliable monitoring of fishing data.

In: Crustaceana
Author: Santanu Mitra

Abstract

A new genus and species of gecarcinucid crab are described here from the Namdapha Tiger Reserve of Arunachal Pradesh, India; Abortelphusa namdaphaensis gen. et sp. nov. is morphologically distinct from other related genera, like Phricotelphusa Alcock, 1909, Globitelphusa Alcock, 1909, Liotelphusa Alcock, 1909, and in having a discrete suite of characters, i.e., carapace squarish, surface randomly pitted, a wide frontal margin ca. 0.5 times the total carapace width; epigastric cristae rugose, post orbital cristae indiscernible; third maxilliped exopod lacking a flagellum; male pleon narrowly triangular, sixth pleonal somite trapezoidal; terminal segment of male first gonopod subcylindrical, outwardly bent, tip not truncated. The relationship of this new genus and species with other gecarcinucid genera from India is discussed.

In: Crustaceana

Abstract

The identity of the potamid freshwater crab, Indochinamon manipurense (Alcock, 1909) from the state of Manipur in northeast India, is clarified based on an examination of the type specimens. The species is redescribed and a lectotype designated. Specimens from the same region previously referred to this species were compared to the types of I. manipurense and shown to belong to a new species of Potamiscus Alcock, 1909, instead. The new species, Potamiscus takedai sp. nov., can easily be separated from I. manipurense by the characters in the carapace, third maxilliped, male pleon, male gonopods, and female vulvae. Potamiscus takedai sp. nov. can be differentiated from congeners mainly by the strongly bent terminal segment of the male first gonopod and a relatively shorter distal segment of the male second gonopod.

In: Crustaceana