Freshwater Crab Research Articles

A new multilocus phylogeny reveals overlooked diversity in African freshwater crabs (Brachyura: Potamoidea): a major revision with new higher taxa and genera

Abstract The taxonomy of 185 species of Afrotropical freshwater crabs is revised to conform to the updated phylogenetic relationships within this large assemblage, based on the largest taxonomic sampling to date (that includes almost all genera and 57% of the species). Four DNA loci were sequenced including three mitochondrial loci (COI, 12S rRNA, 16S rRNA) and one nuclear locus (histone 3), and evolutionary relationships were estimated using maximum likelihood and Bayesian approaches. The divergence times of the major clades were estimated with a Yule tree prior and an uncorrelated lognormal relaxed molecular clock. The taxonomic acts proposed here include the recognition of two Afrotropical families of freshwater crabs (Potamonautidae and Deckeniidae) each with two subfamilies. In the revised Potamonautidae, three new tribes and three new genera (Maritimonautes gen. nov., Nesonautes gen. nov., Occidensonautes gen. nov.), are established, three previously published genera are revised and four subgenera are raised to genus (Arcopotamonautes, Lirrangopotamonautes, Longipotamonautes, Rotundopotamonautes). An updated species list and identification keys for the new taxa, revised distribution maps, digital images and illustrations of diagnostic characters are provided.

A novel gene order and remolded tRNAs revealed in the mitogenome of Asian gecarcinucid freshwater crabs (Brachyura, Gecarcinucidae).

Here we report the first mitochondrial genomes (mitogenomes) of four species of gecarcinucid freshwater crabs (FWCs) in two genera, two from China (Somanniathelphusa hainanensis and S. yangshanensis), one from Laos (Esanthelphusa dugasti), and one from Myanmar (Esanthelphusa keyini). A novel gecarcinucid mitochondrial gene order (GMGO2) that was only found in E. dugasti that contains a total of 42 genes, including one pseudogene, two remolded tRNAs and two duplicated tRNAs. The GMGO2 of E. dugasti was compared with the brachyuran ground-pattern mitochondrial gene order (BMGO), revealing the rearrangements of the positions of 10 tRNAs, two PCGs, and one mNCR. The three other gecarcinucids in this study were all found to possess a previously reported gecarcinucid mitochondrial gene order (GMGO1). The phylogenetic tree reconstructed using the secondary structures of 22 tRNAs of the mitogenomes of 41 species of FWCs provides insights into the evolution of the mitogenome of E. dugasti (GMGO2) which includes remolded and duplicated tRNAs.

A new genus and new species of potamid crab from Yunnan, southern China (Decapoda: Brachyura: Potamidae: Potamiscinae)

Abstract A new genus and new species of freshwater crab, Barbamon zhouigen. nov., sp. nov., belonging to the subfamily Potamiscinae Bott, 1970 (Potamidae Ortmann, 1896) is described from Wenshan Zhuangzu and Miaozu Autonomous Prefecture, Yunnan Province, China. The new genus is established based on a unique combination of characters, including the distinctive shape of the male first gonopod, and the setose ventral surface of the third maxilliped, suborbital and pterygostomial regions, and ambulatory legs. Barbamongen. nov. is similar in external appearance to AbormonMitra, Pati & Ng, 2021. The new genus, however, is distinctive in the combination of characters related to the carapace, third maxilliped, and male first gonopod. Molecular phylogenetic data derived from mitochondrial 16S rDNA sequences provides genetic support for the new genus and species.

Description of a new species of Spiralothelphusa Bott, 1968, and redescription of Spiralothelphusa wuellerstorfi (Heller, 1862) (Decapoda: Brachyura: Gecarcinucidae)

A new species of the gecarcinucid freshwater crab genus, Spiralothelphusa Bott, 1968, is described from the Andhra Pradesh State of South India, with supporting data from mitochondrial cytochrome c oxidase subunit I. This brings the number of known species of Spiralothelphusa to seven, five from India and two from Sri Lanka. The identity of S. wuellerstorfi (Heller, 1862) has remained uncertain because the former lectotype designation was not clear. Bott (1968), while designating a male lectotype of S. wuellerstorfi from the Naturhistorisches Museum Wien, Vienna, Austria, had neither stated the catalogue number nor the size of the specimen. It is now difficult to trace the particular lectotype among several paralectotypes of the depository. A new lectotype is, therefore, designated herein for S. wuellerstorfi, and the species is redescribed. The new species, S. andhra sp. nov., has morphological affinities with S. wuellerstorfi, but can be distinguished from the latter species by the shape of the male telson and outer margin of the non-twisted portion of the male first gonopod. Phylogenetic analyses of the molecular data also corroborate their separation. An illustrated identification key is provided for the species of Spiralothelphusa.

A new species of freshwater crab of the genus Barytelphusa (Decapoda, Brachyura, Gecarcinucidae) from the Eastern Ghats of India

Abstract A new species of gecarcinucid crab, Barytelphusa choprai sp. nov., is described here from the Eastern Ghats in Andhra Pradesh state of India. The new species differs from all three congeners by its convex and trapezoidal carapace, pale white colouration, and by a distinct structure of the male gonopod G1. It differs from its congeners by genetic distance (p-distance) in the range of 5.7-13.6% in partial mtCOI gene sequence. The habitat at the type locality is a slow flowing shallow stream with rocky substratum, covered with silt and debris, and devoid of aquatic vegetation.

Anti-viral activity of methyl 1-chloro-7-methyl-2-propyl-1h-benzo[d] imidazole-5-carboxylate against white spot syndrome virus in freshwater crab (Paratelphusa hydrodromous)

Anti-viral activity of methyl 1-chloro-7-methyl-2-propyl-1h-benzo[d] imidazole-5-carboxylate against white spot syndrome virus in freshwater crab (Paratelphusa hydrodromous)

Freshwater crabs from the highlands of the Venezuelan Guayana

Freshwater crabs from the highlands of the Venezuelan Guayana

Two new genera and a new species of freshwater crabs from northern Madagascar: Vahatra gen. nov. for Foza ambohitra Cumberlidge and Meyer, 2009, and Toamasina gen. nov. for Toamasina clarki sp. nov. (Brachyura: Potamoidea: Deckeniidae)

ABSTRACT Vahatra gen. nov. is established to accommodate Foza ambohitra Cumberlidge and Meyer, 2009 from northern Madagascar, and Toamasina gen. nov. is erected for a genetically distinct new species (Toamasina clarki sp. nov.) that was formerly included in F. ambohitra. These new taxa are recognised based on combinations of morphological characters and previous molecular data. Vahatra ambohitra (Cumberlidge and Meyer, 2009) comb. nov. and Toamasina clarki sp. nov. are both endemic to Madagascar and are distinguished from other species formerly assigned to Foza Reed and Cumberlidge, 2006 and from the other genera of freshwater crabs occurring in that country. The removal of F. ambohitra from Foza leaves this genus with two species, F. raimundi Reed and Cumberlidge, 2006, and F. manonae Cumberlidge, Klaus, Meyer and Koppin, 2015, both of which are illustrated here and compared with the two new genera. http://www.zoobank.org/urn:lsid:zoobank.org:pub:A2CCB977-3164-4AC3-BB36-EC570C580EBD http://www.zoobank.org/urn:lsid:zoobank.org:act:0EAE4ABE-C20F-4964-A51A-22C467F4A67B http://www.zoobank.org/urn:lsid:zoobank.org:act:D97E56CE-8EB7-4272-AB99-C4CC5981665C http://www.zoobank.org/urn:lsid:zoobank.org:act:7B6813DA-23EC-46F7-811B-501D4FC5BB7C http://www.zoobank.org/urn:lsid:zoobank.org:act:BD7B2919-F6E4-4C15-B3D9-E4B650602064

A taxonomic revision of the freshwater crab genusBarytelphusaAlcock, 1909 (Decapoda: Brachyura: Gecarcinucidae), with descriptions of a new genus and three new species

AbstractThe taxonomy of the gecarcinucid crab genus Barytelphusa Alcock, 1909, native to peninsular India, is revised. The genus was formerly known from as many as 13 species and four varieties. We examined their name-bearing type specimens, and to stabilise their taxonomy, designated lectotypes for Potamon (Potamonautes) jacquemontiRathbun, 1905, Thelphusa guerini H. Milne Edwards, 1853, and Telphusa pocockianaHenderson, 1893, and a neotype for Thelphusa cunicularis Westwood in Sykes, 1836. With most of the species already assigned to other genera in previous works, we restrict Barytelphusa s. str. further to only two species, i.e., Barytelphusa cunicularis (Westwood in Sykes, 1836), and a new species described herein, Barytelphusa inflatasp. nov.Potamon (Potamonautes) jacquemonti, the type species of the genus, is here synonymised with Barytelphusa cunicularis. A new genus, Barusagen. nov., is established to accommodate two species placed previously in Barytelphusa (Thelphusa guerini and Paratelphusa (Barytelphusa) mccanniChopra & Das, 1935) and two new species (Barusa gracillimasp. nov. (type species) and Barusa obesasp. nov.). Thelphusa planata A. Milne-Edwards, 1869, and Telphusa pocockiana remain as junior synonyms of Barusa guerini (H. Milne Edwards, 1853) comb. nov.Barusagen. nov. resembles Barytelphusa but can be differentiated by several significant characters of the carapace, antennae, cheliped, male pleon, and male first gonopod. Identification keys to the species of both genera are provided. The taxonomy of Potamon napaeum Alcock, 1909, placed previously in Barytelphusa, and more recently in TravancorianaBott, 1969, is also clarified, and the species is now reassigned to MaydelliathelphusaBott, 1969.

Combined multigene and morphological analysis reveals lineage-specific diversification of the neotropical freshwater crabs of the genus Fredius Pretzmann, 1967 (Brachyura, Pseudothelphusidae)

The pseudothelphusid freshwater crabs of the genus Fredius Pretzmann, 1967 are distributed throughout northern South America and currently include 15 species. We investigated the phylogenetic relationship within the genus using mitochondrial (16S rRNA and COI) and nuclear (H3) genes for most of its representatives. Our set of molecular results (10 species) indicate that Fredius, as currently recovered, is formed by species included in three main lineages. In addition, the results revealed inconsistencies in the morphological identification of some species against the molecular positioning in the topology and suggested the presence of cryptic species, which must be morphologically reanalysed.

The Mitochondrial Genome of the Freshwater Crab Potamon fluviatile, the First Sequenced Representative of the Subfamily Potaminae and Its Phylogenetic Position within Potamidae

This paper reports the mitogenome of Potamon fluviatile collected from the Maltese islands, representing the first such study on species from the subfamily Potaminae. The mitogenome was analysed through next-generation sequencing and annotated. The genome was found to contain 37 genes that include 13 protein coding genes, 22 tRNA genes, two rRNA genes and a non-coding region. The gene order was compared to that of other Potamidae species, while protein coding and rRNA genes were used to evaluate the phylogenetic position of Potamon with other species of freshwater crabs. This study contributes to the genetic resources available for the genus Potamon.

Reproductive behaviour of the North African freshwater crab Potamon algeriense (Bott, 1967) (Brachyura: Potamidae)

ABSTRACT Laboratory and field observations of courtship, copulation, spawning, incubation, and maternal care were made on the endemic North African freshwater crab Potamon algeriense. Mating occurred throughout the year but no discernible courtship behaviour was recorded. However, a forced copulation strategy is practiced by the larger males. The occurrence of ovigerous females extended from June to September with a peak in July (38%). Spawning behaviour took place out of the water and the incubation period lasted 45 ± 2 days. Ovigerous females returned to the stream a few hours before hatching of the eggs. The occurrence of brooding females (females carrying juvenile crabs) extended from July to October, with the highest number in August (36%). Posthatching maternal care was recorded, which lasted between 7 to 10 days before juveniles left their mother’s abdominal cavity for an independent life.

Allometric Relationship of Freshwater Crabs Oziotelphusa bouvieri and Spirallothelphusa wuellerstorfi of Puzhal Lake, Chennai, Tamil Nadu, India

Freshwater crabs are the most dominant and specifically endemic species in India. Ecologically and nutritionally freshwater crabs proved to be the best alternative for marine crabs. Culturing of freshwater crabs are less tedious than freshwater fishes but lack of proper research on stock assessment becomes major drawback. Stock assessment helps in evaluating actual population dynamics in order to assess its population density which would be further used for designing aquaculture practices. Simple regression proved to be effective statistical tool for calculating relative growth. Due to very fragmentary work on allometry of freshwater crab species, there is an urgent need to evaluate the actual population dynamics of freshwater crabs.

Temnosewellia aff. vietnamensis (Platyhelminthes: Rhabdocoela: Temnocephalidae) associated with freshwater crabs from Kagoshima, southern Japan, with review of records of the genus from East to South Asian countries.

Temnocephalids are ectosymbionts of various freshwater animals. A species tentatively identified as Temnosewellia aff. vietnamensis (Platyhelminthes: Rhabdocoela: Temnocephalidae) is reported based on materials collected from the body surface of the freshwater crabs Eriocheir japonica (Brachyura: Varunidae) and Geothelphusa exigua (Potamidae) in Kagoshima, southern Japan. The temnocephalid is characterized as follows: the cirrus composed of a cone-shaped shaft and a cylindrical introvert 42-77 μm long; the introvert covered with approximately 30 vertical rows of fine sharp spines; the four seminal receptacles; and a long, curved oviduct with vaginal gland; a pair of gland cells (Haswell's cells) present anterior to the excretory ampullae. Bayesian inference trees using partial nuclear 28S rDNA (28S) and mitochondrial cytochrome c oxidase subunit I (COI) genes supported that the specimens collected from both crab species are conspecific but these also showed the geographical variations among them on both 28S and COI. The previous records of the genus Temnosewellia in East to South Asian countries are assembled and shown on the map (fig.7, this paper).

Sporadic endemicity of zoonotic Paragonimus in raccoon dogs and Japanese badgers from Miyazaki Prefecture, Japan.

Paragonimiasis is a zoonotic trematode infection caused by Paragonimus spp. To determine the recent status of Paragonimus infections in wild animals, this study investigated Paragonimus spp. in 39 raccoon dogs and 54 Japanese badgers from March 2019 to January 2021 in Miyazaki Prefecture, and examined metacercariae in freshwater crabs. Triploid P. westermani was found in one raccoon dog (2.6%), and metacercariae were recovered from Eriocheir japonica captured near the infected animal collected. One Japanese badger (1.9%) harbored P. skrjabini miyazakii; this prevalence was lower than the approximately 30% that was reported in the 1970s. Results indicated that zoonotic Paragonimus was sporadically prevalent in wild animals. Further investigation in various animals is awaited to elucidate current wildlife reservoirs for those Paragonimus.

Brachyuran crabs (Crustacea: Decapoda) in the limestone caves of Thailand, with a checklist of freshwater cave-dwelling crabs in Southeast Asia

Brachyuran crabs (Crustacea: Decapoda) in the limestone caves of Thailand, with a checklist of freshwater cave-dwelling crabs in Southeast Asia

Multiple metals and agricultural use affects oxidative stress biomarkers in freshwater Aegla crabs

Metals and agrochemicals are among the main aquatic contaminants, being able to trigger oxidative stress in exposed organisms. The objective of this work was to evaluate the correlation between the level of oxidative stress biomarkers in Aegla crabs (Crustacea, Anomura) with (i) the set of metals present in the streams sediment and (ii) with land uses of three hydrographic basins. The study was carried out in streams (≤ 2nd order) of hydrographic basins in southern Brazil (Basins of Rio Suzana, Rio Ligeirinho-Leãozinho and Rio Dourado). In these streams were quantified the land uses and Cu, Cr, Cd, Fe, Mn and Zn concentrations in the sediment. The enzymes Catalase (CAT) and Glutathione Reductase (GR), as well as the level of membrane lipid peroxidation (TBARS), were analyzed in adult females. The PCA analysis showed that the distribution of metals was different between the basins. Cd, Cr and Fe were correlated positively with CAT and negatively with TBARS and GR. The Dourado basin had the lowest concentrations of these three metals and the highest levels of TBARS. However, in Dourado basin there is predominance of agriculture land use, and TBARS was positively correlated with agricultural land use. Besides in Dourado basin, GR activity was higher than in the others basins, indicating a compensatory response in relation to CAT inhibition. The basins of Suzana and Ligeirinho-Leãozinho rivers had lower TBARS values, which may be due to the induction of CAT in response to metals accumulated in sediment. In summary, this work indicates that in the basins with a higher concentration of toxic metals there is an adaptive response of CAT induction, which reduces TBARS in Aegla. On the other hand, in the basin with lower metallic contamination, TBARS occurrence was primarily influenced by agricultural land use.

Current status of the treatment of paragonimiasis

Paragonimiasis, a foodborne trematodiasis is caused by various Paragonimus species endemic in Asia, Africa, and the Americas. Human infection occurs through consuming improperly cooked freshwater crustaceans, crabs or crayfish, eating raw meat of paratenic hosts or by ingesting metacercariae from contaminated hands and cooking utensils. More than 292 million persons worldwide are at risk. The morbidity associated with paragonimiasis includes acute febrile illness and chronic pleuro-pulmonary manifestations which may be confounded with tuberculosis or lung cancer. Ectopic manifestations mostly involve the central nervous system, heart, or subcutaneous tissues. Objectives: to evaluate the efficacy and safety of currently available drugs praziquantel (PZQ) and triclabendazole (TCZ). Methods: a PubMed and Google Scholar search and reference selection was performed according to the the Preferred Reporting Items for Systematic Reviews protocol using a combination of the terms “paragonimiasis” AND “treatment” OR “therap*” from 01/2000 to 02/2022. Results: no randomized controlled trials were identified. Five open trials on 487 patients treated with PZQ showed 81%-100% parasite clearance depending on dosage and duration. Three open trials on 226 patients with TCZ showed a 99.6% efficacy. A quantitative comparison was not applicable to retrospective analyses of hospital records, case series and case reports because of surgical interventions, various co-morbidities and -medications and definitions of cure. Some patients treated with PZQ required multiple courses or re-treatment with TCZ, whereas one patient treated with TCZ required re-treatment with PZQ. Conclusions: PZQ and TCZ are usually effective for treating paragonimiasis. Controlled randomized trials are required to compare the safety, efficacy and applicability of PZQ versus TCZ and to evaluate combined PZQ-TCZ therapy.

Effect of Sub-lethal Concentration of Tributyltin Oxide on Enzyme Activity of Fresh Water Crab Barytelphusa cunicularis

The present study was conducted to determine the effect of organotin compound on alteration of enzyme activity in fresh water crab Barytelphusa cunicularis exposed to sub-lethal concentrations of tributyltin oxide (TBTO) (0.244 ppm which is 1/10th of 96 h LC50). The LC50 value of TBTO were found as 5.29 ppm for 24 h and 2.44 ppm for 96 h. Crabs (Barytelphusa cunicularis) were exposed to sub-lethal concentrations (0.244 ppm) of TBTO for 7, 14, 21 and 28 days. The activity of enzymes Aspartate aminotransferase (AST), Alanine aminotransferase (ALT) and Alkaline phosphatase (ALP) in the hemolymph of crabs showed significant increase after exposure to 0.244 ppm TBTO for 28 days. The increase metabolic enzymes in hemolymph of treated animals compared with control indicated heaptopancreatic damage caused by TBTO. These changes are an outcome of metabolic as well as physiological stress.

ABUNDANCE AND MORPHOLOGICAL CHARACTERIZATION OF WEST AFRICAN FRESHWATER CRAB (SUDANOUNTES AFRICANUS) ALONG LOWER RIVER BENUE, MAKURDI, BENUE STATE NIGERIA

The abundance and morphological characterization of freshwater crab (Sudanountes africanus) were determined in Makurdi along the Lower River Benue. 160 Sudanountes africanus were collected from August-November, 2016. The highest percentage (35.63%) S. africanus was obtained in August while the lowest (12.50%) was obtained November. The mean total length, body weight, carapace width, carapace length, length of the teeth, abdominal length, number of legs and diameter of the eye socket of male S. africanus were 3.38±0.03, 38.52±0.84, 4.67±0.83, 1.44±0.18, 3.51±0.06, 2.91±0.06, 8.00±0.00 and 0.69±0.01, respectively while the female counterpart had 3.40±0.07, 37.63±1.77, 4.71±0.10, 1.43±0.15, 3.26±0.08, 2.72±0.08, 8.00±0.00 and 0.64±0.01, respectively. There was no significant difference (p>0.05) between mean total length, body weight, carapace width, carapace length, abdominal length and the diameter of the eye socket. Female S. africanus had better “b” value (16.56) and mean condition factor (36.18±1.22) than the male with 7.13 “b” value and 7.16±4.77 condition factor. From the width weight relationship, female S. africanus had better “b” value (11.22) and mean condition factor (9.20±2.09) than the male with 2.00 “b” value and 1.07±4.45 condition factor.