Postabdominal Claw Research Articles

South-East Asian populations of Karualona cf. karua (King. 1853) (Crustacea: Cladocera: Chydoridae) belong to a separate species.

Study of populations of Karualona cf. karua (King, 1853) (rustacea: Cladocera) from South-East Asia and Sri Lanka revealed that they belong to an undescribed taxon. Karualona fatimae sp. nov. differs from the Australian K. karua s. str. by a very small basal spine of postabdominal claw and the presence of small denticle on the anterior margin of labral keel. The latter character is unique for the genus. Morphology, distribution and phylogenetic position of the new species are discussed. Our data suggest that the diversity of Karualona is underestimated in most tropical regions, with at least one more undescribed taxon present in South-East Asia and one more taxon in Australia. An updated key for genus Karualona Dumont & Silva-Briano, 2000 of the Eastern Hemisphere is provided.

Synergistic toxicity of some cyanobacterial oligopeptides to physiological activities of Daphnia magna (Crustacea)

Anabaenopeptins and microcystins are oligopeptides produced by bloom-forming cyanobacteria. We determined in vivo effects of anabaenopeptin-B (AN-B) and two variants of microcystins of different hydrophobicity (MC-LR and MC-LF) on the physiology of Daphnia magna. Heart rate, thoracic limb activity and post-abdominal claw activity were determined by digital video analysis and oxygen consumption by Oxygraph + system. EC50 calculation and isobole methodology for interactive effects of AN-B and MC-LR mixture were used.Daphnids' responses to all three oligopeptides were concentration- and time-dependent. MC-LF was the most potent inhibitor of heart rate, thoracic limb activity, post-abdominal claw activity and oxygen consumption. AN-B was more toxic than MC-LR toward oxygen consumption; it inhibited the movements of limbs and post-abdominal claw similarly to MC-LR, but did not inhibit heart rate. The strongest toxic effects were induced by the binary mixture of AN-B with MC-LR at the sum concentration equal to the concentration of the single compounds. First time direct synergistic toxic effects of the cyanopeptides on all the physiological parameters were found. The obtained results explain stronger disturbances in aquatic organisms caused by cyanobacterial cell contents than the individual cyanopeptides present even at higher concentrations. Other metabolites and their interactions need further studies.

Short-term effects of pesticide fipronil on behavioral and physiological endpoints of Daphnia magna

Fipronil (FIP) is an organic pesticide with many practical uses. Although some results indicated toxic effects in some terrestrial and aquatic animal species, little is known on its influence on behavioral and physiological endpoints of cladocerans. The aim of our study was to determine the short-term effects of FIP at concentrations of 0.1 μg/L, 1 μg/L, 10 μg/L, and 100 μg/L on Daphnia magna sublethal indices: behavioral (swimming speed, distance traveled) and physiological endpoints (heart rate, post-abdominal claw activity and thoracic limb movements). The results showed that FIP induced reduction of swimming speed and distance traveled in a concentration- and time-dependent manner at all the concentrations used. The lowest concentration of the insecticide temporarily stimulated post-abdominal claw activity after 24 h and thoracic limb activity after 48 h; however, the highest concentrations reduced all the studied physiological endpoints. IC50 values showed that thoracic limb activity, swimming speed, and distance traveled were most sensitive to FIP after 24-h exposure. The most sensitive parameter after 48 h and 72 h was swimming speed and post-abdominal claw activity, respectively. The study indicated that (i) behavioral and physiological endpoints of Daphnia magna are reliable and valuable sublethal indicators of toxic alterations induced by FIP; however, they respond with different sensitivity at various times of exposure, (ii) FIP may alter cladoceran behavior and physiological processes at concentrations detected in the aquatic environment; therefore, it should be considered as an ecotoxicological hazard to freshwater cladocerans.

A new species of the Daphnia sinevi group (Crustacea: Cladocera: Daphniidae) from Sakhalin Island, Russian Far East.

Daphnia curvirostris species complex is a cladoceran group (Crustacea: Cladocera) with maximum diversity in Eastern Palearctic. To date, several representatives of this complex are known from the Russian Far East. Here we describe a new species of the Daphnia sinevi species group from water bodies of Sakhalin Island. Morphology of its parthenogenetic females is similar to that in D. sinevi from the continental part of Asian Eurasia. However, we found diagnostic traits of D. sakhalinensis sp.nov. in morphology of the second pecten on postabdominal claw, armature of seta 2 on exopodite III, proportions of setae 1/ and 2 length on exopodite V, relative length of male rostrum and structure of the second pecten of male postabdominal claw. This work contributes to our full revision of the D. curvirostris species complex. Separation between continental and Sakhalin populations of D. sinevi group probably happened in Pliocene (about 5 MA) when Sakhalin began to separate from the mainland. However, we cannot exclude a version that populations of D. sakhalinensis sp.nov. appeared as a result of colonization of Sakhalin from the continent and further independent evolution of the island populations.

New species of Alpinalona Alonso amp; Sinev, 2017 (Cladocera: Anomopoda: Chydoridae) from South-East USA.

A new species of genus Alpinalona Alonso Sinev, 2017 is described from South-East USA. Alpinalona fornshelli sp. nov. differs from other species of the genus in: (1) over 35 setulae on posteroventral angle of the valves, organized into 5-6 groups; (2) a long basal spine of female postabdominal claw (about 0.3 claw length); and (3) thick long distalmost spines in basal pecten of postabdominal claw. Taxonomic position and distribution of the new species are discussed.

Saxitoxin-producing Raphidiopsis raciborskii (cyanobacteria) inhibits swimming and physiological parameters in Daphnia similis

In this study we tested the effects of a neurotoxic strain of the cyanobacterium Raphidiopsis raciborskii (CYRF-01) on the swimming activity and physiological parameters of Daphnia similis such as movements of the antennae, thoracic limbs, post-abdominal claw and heart rate. An acute assay was performed to test the effect on swimming activity, exposing newborns (<24 h) to different concentrations of live cells and observing the number of immobilized animals over a period of 48 h. For testing the effects on physiological parameters adult females (10–15 days) were exposed in a flow-through system and recorded with a digital camera. Results showed rapid effect of the strain CYRF on all parameters. Animals started to be immobilized in the first 30 min exposure and showed complete paralysis after 2 h in 500 μg L−1 and after 24 h in the other concentrations. Physiological parameters accompanied the same response pattern with effects starting after 30 min and some recovery at the end of 6 h exposure. Antennae stopped moving after 2–3 h at 250–500 μg L−1, explaining the paralysis of the swimming activity in Daphnia. Thoracic limbs movements were significantly inhibited after 30 min in all concentrations, staying at lower levels than control through the experiment. Post-abdominal claw movement were completely ceased after 30 min and remained stopped until the end of the trial. Heart rate showed a tendency to decrease abruptly in the first 30 min exposure in all concentrations, but showed significant lower values than control only at 500 μg L−1, between 3 and 4 h exposure, and a recovery at the end of 6 h. In conclusion, results show that neurotoxic cyanobacteria can impose severe constrains on the physiology of daphniids, which can have consequences to the oxygen uptake, swimming and feeding behavior and to the overall fitness of those organisms.

A new case of false "wide" distribution for tropical cladocerans: the genus Notoalona Rajapaksa amp; Fernando, 1987 (Crustacea: Cladocera) in the Old World.

Members of the genus Notoalona Rajapaksa Fernando, 1987 (Cladocera: Chydoridae: Aloninae) are small-sized chydorids, inhabiting tropical water bodies around the World. Based on morphological features two species, N. globulosa (Daday, 1898) and N. pseudomacronyx Van Damme, Maiphae Sa-Ardrit, 2013, were revealed in tropical Asia, but the status of African populations has remained unclear for a long time. Some authors identified African specimens as N. globulosa, others considered them as potentially new species awaiting description. Here we reexamined morphology of Notoalona populations from tropical Asia (Thailand, Laos) and Africa (Ethiopia, Kenya, Sudan and Madagascar). Although parthenogenetic females from Asia and Africa are basically similar, a single stable difference was found. In N. globulosa, the length of the basal spine and claw base are almost equal to each other, while in all investigated African specimens the basal spine is two times longer than base of postabdominal claw. This feature allows us to identify African populations as N. pseudomacronyx. Length of the setules in the basal group near the postabdominal basal spine, which was previously discussed in the literature as a specific feature for African populations, in fact, is overly variable and cannot be considered as diagnostic characteristic for the description of African populations as a separate taxon. Thus, the distribution range of N. pseudomacronyx is hereby expanded from South Africa to South East Asia, while N. globulosa s.l. occupies water bodies from tropical Asia to Australia. The same distribution patterns, when sibling species occur together in tropical Asia, have been shown for some other cladocerans as well. No doubt, the Asian tropics may be a particularly interesting area for future investigations on co-occurrence of sibling cladocerans, their ecology, behavior, genetics and potential hybridization.

Identifying invasive Daphnia species by morphological analysis of postabdominal claws in Sierra Nevada alpine lakes

Sedimentary postabdominal claws, among other remains, have been used successfully in paleolimnological studies to reconstruct past environmental conditions and the distribution pattern of certain Daphnia species. However, morphological analysis of postabdominal claws has not proven adequate for the clear taxonomic differentiation among species within a complex, such as the Daphnia pulex complex. The presence of the invasive North American (NA) D. pulex lineage was recently detected in an alpine lake in the Sierra Nevada mountain range (Southeast Spain). This lineage has spread throughout Africa and the Mediterranean basin, suggesting a trend towards its increased presence in Europe. The aim of this study was to examine whether this invasive lineage could be differentiated from the native European (Eu) Daphnia pulicaria lineage based on morphological differences in postabdominal claws recovered from three alpine lakes in the Sierra Nevada. The most useful differential variables were the postabdominal claw length (PCL), ratio of distal comb length to PCL (Cldist/PCL), and number of stout spines. Thus, NA D. pulex may be identifiable by a short PCL, low Cldist/PCL value and the presence of < 5 stout spines. Because of a wide variability in PCL within the Eu D. pulicaria species and an overlap in stout spine number between the species, morphological analysis results cannot unequivocally differentiate these lineages. However, they make a useful contribution to recognition of the possible presence of this invasive lineage. The present findings assist identification of the invasive NA D. pulex lineage in potentially affected regions, facilitating reconstruction of its historic dispersion and colonization.

Genus Camptocercus (Cladocera: Anomopoda: Chydoridae) in North America.

Genus Camptocercus is represented in North America by four species. Camptocercus rotundus Herrick, 1882 is proved to be a valid species and is redescribed here. C. rotundus differs from its sibling species, neotropical C. dadayi Stingelin, 1913, in morphology of the postabdominal claw, presence of posteroventral denticles on valves, and morphology of the male postabdomen. C. rotundus is distributed in South Canada and North USA from Pacific to Atlantic coast, whereas C. dadayi is found in Mexico and South-East USA. C. oklahomensis Mackin, 1930 is found in Central USA. C. streletskaye Smirnov, 1998, previously known from Chukotka and Magadan Area of Russia, was found in Alaska for the first time.

Effects of apomorphine, a dopamine agonist, on Daphnia magna: Imaging of swimming track density as a novel tool in the assessment of swimming activity

Apomorphine (APO) is a non-selective agonist of dopamine receptor activating D2-like receptors. Although Daphnia has been used in neurotoxicology in toxicity testing, little is known on its behavioural and physiological responses to dopamine receptors ligands. Therefore, the aim of our study was to determine swimming behaviour (swimming track density, speed, turning activity) and physiological parameters such as heart rate, thoracic limb activity and post-abdominal claw movement frequency in daphnids exposed for 1, 2 and 4h to concentrations of 0.3, 3 and 30mg/L of APO. The results showed the most significant decrease of behavioural endpoints such as swimming track density, speed and degree of turning angles of daphnids exposed for 4h to the highest concentrations of APO. The study also showed that a decrease of thoracic limb activity was found after 2 and 4h but only at the highest concentration. Heart rate was not affected by APO which may be a result of a lack of signalling with dopamine receptors in the heart of Daphnia. Therefore, activity of this organ seems to be not a valuable physiological biomarker in the assessment of effects induced by dopamine receptor ligands. The study also showed that our new methodological approach, imaging of swimming track density may be a promising tool for studying the effects of neuroactive substances on locomotor system activity of Daphnia magna.

Populations of Flavalona setigera (Brehm, 1931) in Brazil belong to a new species: Flavalona asymmetrica (Cladocera: Chydoridae: Aloninae)

Abstract Flavalona asymmetrica sp. nov. belongs to the costata-clade. This species has two main head pores, a feature shared only with Flavalona setigera (Brehm, 1931). Morphological differences between them are related to main and lateral head pores, armature of scrapers on the second limb, and proportion of setae on the third and fourth limbs, number of denticles on the postabdomen. Males of F. asymmetrica sp. nov. has genital process about ten times shorter than length of postabdominal claw, which is an exclusive morphological trait. Flavalona asymmetrica sp. nov. is a Neotropical species, so far, it occurs only in Brazil and can be found together with Flavalona iheringula (Sinev & Kotov, 2004) and Flavalona margipluma (Sousa, Santos, Guntzel, Diniz-Filho, de Melo-Junior & Elmoor-Loureiro, 2015).

Time-gated luminescence imaging of singlet oxygen photoinduced by fluoroquinolones and functionalized graphenes in Daphnia magna

Singlet oxygen (1O2) can be photogenerated by photoactive xenobiotics and is capable of causing adverse effects due to its electrophilicity and its high reactivity with biological molecules. Detection of the production and distribution of 1O2 in living organisms is therefore of great importance. In this study, a luminescent probe ATTA-Eu3+ combined with time-gated luminescence imaging was adopted to detect the distribution and temporal variation of 1O2 photoinduced by fluoroquinolone antibiotics and carboxylated/aminated graphenes in Daphnia magna. Results show that the xenobiotics generate 1O2 in living daphnids under simulated sunlight irradiation (SSR). The photogeneration of 1O2 by carboxylated/aminated graphenes was also confirmed by electron paramagnetic resonance spectroscopy. The strongest luminescence signals of 1O2 were observed in the hindgut of daphnids, and the signals in different areas of the daphnids (gut, thoracic legs and post-abdominal claw) displayed a similar trend of enhancement over irradiation time. Mean 1O2 concentrations at different regions of daphnids within one hour of SSR irradiation were estimated to be in the range of 0.5∼4.8μM. This study presented an efficient method for visualizing and quantifying the temporal and spatial distribution of 1O2 photogenerated by xenobiotics in living organisms, which can be employed for phototoxicity evaluation of xenobiotics.

New genus of Cladocera of subfamily Aloninae (Anomopoda: Chydoridae) from the Mekong River

A rheophylous cladoceran, Rheoalona mekongensis sp. nov., gen. nov. (Anomopoda: Chydoridae: Aloninae) is described from the Mekong River, South-East Asia. Rheoalona gen. nov. belongs to the Coronatella-branch of Aloninae, it differs from Karualona Dumont &amp; Silva-Briano, 2000 in absence of seta 1 of IDL of thoracic limb I and by particularly strong lateral setae of postabdomen; from Anthalona Van Damme, Sinev &amp; Dumont, 2011 in a wide connection between major head pores, lack of cosmaria, and two-flaming torch setae of limb IV; and from Coronatella Dybowski &amp; Grochowski, 1894 in two major head pores, very small elementary denticles of postabdomen, and a very small basal spine of postabdominal claw. R. mekongensis sp. nov. is specially adapted for dwelling in the upper layer of fine sediments of turbid rivers. Our finding stress the importance of sampling in riverine habitats for the full inventories of the cladoceran fauna.

The amazing diversity of the genus Monospilus Sars, 1862 (Crustacea: Branchiopoda: Aloninae) in South America.

The main goal of this paper is to describe three new species of the genus Monospilus Sars, 1862 (Crustacea: Cladocera). Monospilus macroerosus sp. nov. differs from other species of the genus in several peculiar morphological traits, the most striking being the presence of a saw-shaped pecten of teeth on the postabdominal claw. This species inhabits semiterrestrial habitats (wet leaf litter on hydromorphic soil from gallery forest), exhibiting adaptations related to movement and food handling in this type of habitat. Monospilus brachyspinus sp. nov. inhabits truly aquatic habitats, where lives being associated with macrophytes and submerged leaves. It may be recognized by the postabdominal claw, which is armed with proximal spinulae modified in a short spine. In Monospilus sp., the proximal spinulae are modified in a long and slender spine. So far, Monospilus sp. occurs in southern South America, while Monospilus macroerosus sp. nov. and Monospilus brachyspinus sp. nov. occur in the Cerrado biome in Brazil, in the central portion of South America. Some conclusions about the conservation status of new species also are made.

Position of the dentifera-group in the Coronatella-branch and its relocation to a new genus: Magnospina gen. n. (Crustacea, Chydoridae, Aloninae).

Magnospina gen. n. was created to relocate species of the dentifera-group from Alona sensu lato (Crustacea: Cladocera) and include Magnospina dentifera comb. n. and Magnospina siamensis comb. n. The synapomorphies of the Magnospina gen. n. are (1) basal spines longer than 2/3 of the postabdominal claw, (2) presence of 1–4 large denticles, broad at their bases, protruding downwards, without setules between them. Morphological traits such as habitus, rostrum and postabdomen shape, armature of IDL setae, number of setae on the exopod of limb III are also important in the distinction between Magnospina gen. n. and other genera from the Coronatella-branch. The morphology of Magnospina dentifera comb. n. male confirms the closer relationship with the clade composed by the elgans-group from Alona sensu lato, Ovalona and Leberis, but the external morphology, morphology of the postabdominal claw, basal spine and setae 2–3 of IDL support their separation from any of the group cited. It is concluded that the Coronatella-lineage of Aloninae is composed of the genera Coronatella, Anthalona, Karualona, Bergamina, Extremalona, Ovalona, Celsinotum, Leberis and Magnospina gen. n. The elegans-group from Alona sensu lato also belongs to Coronatella-lineage, but still need formal allocation.

Description of the male of Coronatella paulinae (Crustacea, Branchiopoda, Chydoridae) with an identification key for the genus based on the male morphology

Cladoceran males are not very frequent in natural populations, since they are only produced in stress situations. Thus, only a few species have had the male morphology described. Nevertheless, whenever data concerning the morphology of males is available, they are used as a tool to resolve taxonomic problems. In this study, the morphology of Coronatella paulinae Sousa, Elmoor-Loureiro and Santos, 2015 (Cladocera: Chydoridae) was described and compared to other species within the genus. Coronatella paulinae shares the diagnostic morphological traits typically attributed to the genus: (1) gonopores opening ventrally, subapically to the postabdominal claw; (2) marginal setulae arranged in groups on the postanal margin; (3) Inner Distal Lobe (IDL) armed with three setae, of which one is the male seta. The absence of lateral aesthetascs on male antennules might also be an important diagnostic character for the genus, since they are present in other Aloninae groups. Coronatella paulinae males present a unique combination of morphological traits on the postabdomen, which distinguish them from other Coronatella Dybowsky and Grochowski, 1894 species, such as a marked postanal angle and an almost straight basal spine, longer than the mid-length of the postabdominal claw.

New records of Anthalona acuta Van Damme, Sinev & Dumont 2011 and Anthalona brandorffi (Sinev & Hollwedel, 2002) in Brazil, with description of a new species of the simplex-branch (Crustacea: Cladocera: Chydoridae).

The range of geographical distribution of Anthalona acuta Van Damme, Sinev & Dumont 2011 and Anthalona brandorffi (Sinev & Hollwedel, 2002) in Brazil has increased by almost 2000 km to the south. New records of Anthalona verrucosa verrucosa (Sars, 1901) were also added. Populations of Anthalona brandorffi from Central Brazil showed a peculiar morphological variation, with some individuals having only a single denticle on the labral keel. A new species of the simplex-branch, Anthalona neotropica sp. nov., was described based on Brazilian material, and this is the first taxon of this branch registered in the Neotropics. It differs from Anthalona simplex Van Damme, Sinev & Dumont 2011, a Central African species, in the morphology of underneath sack of the lateral head pores, length of IDL setae and armature of first flaming-torch seta of limb IV. It could be distinguished from Anthalona sanoamuangae Sinev & Kotov, 2012 (distributed through the South- East Asia) by the morphology of the main head pores, length of IDL setae and armature of the pecten of postabdominal claw. Anthalona neotropica sp. nov. seems to have a benthic/hyporheic habit. All studied species have a wide geographical distribution and could be confused with Anthalona verrucosa Sars, 1901, thus at least some if not all previous records of this species on the continent must be revised.

A new species of Leberis Smirnov, 1989 (Cladocera: Chydoridae) from Colombia.

A new species of Leberis Smirnov 1989 (Cladocera: Chydoridae) is described based on the material from Ciénaga El Convento (Atlántico Department), Ciénaga Grande de Santa Marta (Magdalena Department), and Laguna Navío Quebrado (La Guajira Department), Colombia. In the Neotropics, Leberis colombiensis sp. nov. could be confused with L. davidi Richard, 1985. But the former differs from the latter in: (1) smaller size; (2) smaller post-pore distance; (3) gonopore region on male postabdomen un-inflated, not overhanging base of postabdominal claw; (4) shorter postanal portion of male postabdomen. Diversity of the genus worldwide is underestimated yet. We believe that more species of Leberis will be described in the future, i.e. after molecular genetic studies.

Leydigia (Neoleydigia) cf. striata Birabén, 1939 (Crustacea: Cladocera: Chydoridae) from Colombia and its differentiation from L. (N.) cf. ipojucae (Brehm, 1938)

This paper concerns the chydorid cladoceran Leydigia (Neoleydigia) cf. striata Birabén, 1939 in plankton samples from Ciénaga El Convento, Colombia. The specimen from Colombia bears the diagnostic features of L (N) cf. striata as redescribed by Kotov and Elías-Gutiérrez (2003), Kotov et al. (2004), and Kotov, (2009). However, this particular specimen shows some subtle differences in the morphology of basal spine of claw, spine-like setules on first and second endopod segments of antenna II, and striation on valve. In the Neotropics, L. (N.) cf. striata Birabén, 1939 most closely resembles L. (N.) cf. ipojucae Brehm, 1938 in the structure of thoracic limb II and postabdominal claw, but can be separated from the latter by differences in setules in lateral fascicles on labrum, postpore distance (PP), shape of postabdomen, preanal margin of the postabdomen, and seta 2 of thoracic limb III.

A new and a rare species of Chydorus Leach, 1816 (Branchiopoda: Cladocera: Anomopoda) from Cat Tien National Park, Vietnam

The present study of cladocera of the genus Chydorus from South Vietnam revealed a new species, C. idrisi sp. nov. and a rare species, C. breviceps (Stingelin, 1905). C. idrisi sp. nov. belongs to the C. eurynotus Sars, 1901 group, characterized by small labral plate with rounded tip and by absence of honeycomb sculpture on the valves. C. idrisi sp. nov. differs from other species of the group by the sculpture of valves, morphology of rostrum, postabdominal claw, inner distal lobe of first thoracic limb and male postabdomen. Morphology of C. breviceps was studied for the first time. C. breviceps has only one major head pore, and differs from the majority of Chydorus species by numerous other characters. Taxonomic position of studied species is discussed.