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(Lilljeborg, 1901) (Copepoda, Cyclopoida, Cyclopidae) was studied using various methods. Molecular genetic methods (comparison of COI and ITSn molecular markers) have shown that this species represents a species complex, and the following methods were used to search for differences between the species: analysis of qualitative and quantitative characters, linear morphometrics, landmark-based geometric morphometrics, and integumental pore pattern of the cephalothorax. from Middle Siberia is described. The two studied species can be considered pseudocryptic; the main morphological difference between the species is the number of setules on the inner side of the first and second exopod segments of the fourth pair of swimming legs: has 6-10 and 7-17 setules, respectively; has 0-3 and 0-6 setules, respectively. The morphometry and integumental pore pattern of the cephalothorax were ineffective for identification and separation of species. The existing previous records of were also analyzed, and the records of this species in the Irkutsk region (Russia), as well as in Japan and Korea, are attributed to

Little is known about the insular diversity and its determinants in the freshwater invertebrates in comparison to land animals. Our goal is to obtain global-scale information on the insular diversity in Cyclopidae, test its relationships with the geographical variables in different types of islands, and compare the patterns to those observed in other organisms. In total 291 species and subspecies were reported in the 35 islands included in our analyses. The total and endemic species richness have strong positive correlations with surface area and maximum elevation of the islands; regression slopes are larger in the oceanic than in continental islands. Small-island effects occur in the relationships between the endemic species richness and area and elevation. Distance from mainland has negative correlations with the total and endemic species richness in the oceanic islands. Compositional similarity (in contrast to species richness) is determined by the geographic variables to only a minor extent, while space has stronger impact. The relationships found in Cyclopidae generally fit those observed in other predominantly terrestrial organisms, yet some characteristics (negative intercepts in the area–species and elevation–species relationships; large area and high elevation thresholds below which no endemic species occurs) are suggested to be specific to fresh waters.

The description of Bryocyclopsasetus sp. n. and the record of B.muscicola (Menzel, 1926) from Thailand are presented. The new species is most similar to B.maewaensis Watiroyram, Brancelj & Sanoamuang, 2012, the cave-dwelling species described from northern and western Thailand. They share morphological characteristics, such as the free margin of the anal operculum which is ovated and serrate, the same setae and the spines formulae on P1-P4Exp-2 (setae: 5.5.5.4; spines: 3.3.3.3) and Enp-2 of P1-P2, P4 (setae formula 3.4.3) in both sexes. The new species is easily distinguished from B.maewaensis due to typical divergent caudal rami, the absence of coxal seta on P1, and the absence of blunt-tipped setae on P2-P3Exp-2. A dichotomous key to the species of Bryocyclops group I sensu Lindberg (1953) is proposed.

In 2003, Paul Hebert proposed DNA barcoding, based on the first half of a standardized gene, the Cytochrome c Oxidase subunit I (COI), to identify animals. Subsequently, two large-scale projects enabled the sequencing of more than 1.3 million putative species worldwide. Two decades ago, we decided to adopt this approach as a tool to investigate the freshwater zooplankton diversity of Mexican aquatic systems. Several copepod species have been described by us with the aid of this marker, mainly of the family Diaptomidae, particularly of the species-rich genera and . We also re-described topotypes of the widespread and documented the invasion of exotic cyclopid species. In Mexico, we have sequenced the COI of 1,725 free-living freshwater copepods, including 925 diaptomid calanoids and 811 cyclopid cyclopoids, representing up to 43.7% of the total specimens sequenced for North America. To delineate the putative species diversity, we used the Barcode Index Number (BIN) and the Assemble Species by Automatic Partitioning method and compared both. For we prepared a Maximum Likelihood (ML) tree, for a detailed analysis. Our results suggest that central-southeastern Mexico may represent a potential radiation center for speciose diaptomid genera like (15 species), (eight species), and , which likely constitutes a regional species complex yet to be described. A comparison of Mexican data with that from North America (NA) showed that the only truly widespread copepod species, distributed from Arctic latitudes to the central Mexican plateau, is , while all others have more restricted distributions. From the total specimens sequenced in NA, the BIN count revealed 89 Molecular Operational Taxonomic Units (MOTUs), but only 47 of them have been identified to species level. In some cases, diaptomid haplotype variants have received different BINs for a single specimen. The taxonomic impediment appears to be more pronounced in Cyclopoida, with only 32% of the total 235 BINs identified to species level. Despite these limitations, the use of MOTUs from these baselines is valuable for biomonitoring changes in freshwater ecosystems. We found that in some cases, mostly where singletons represented a BIN, the Assemble Species by Automatic Partitioning (ASAP) method provided a better representation of MOTUs. Conversely, when haplotypes of different species, such as those found in the complex, are closely similar, ASAP fails, but ML can distinguish them. Therefore, it is urgent to apply an integrative taxonomy approach to propose the most convincing hypotheses regarding these issues. This publicly available online copepod baseline represents a useful tool for exploring and understanding species distributions, detecting possible new species and translocations, and revealing centers of speciation in NA.

Eucyclops speratus (Lilljeborg, 1901) (Copepoda, Cyclopoida, Cyclopidae) was studied using various methods. Molecular genetic methods (comparison of COI and ITSn molecular markers) have shown that this species represents a species complex, and the following methods were used to search for differences between the species: analysis of qualitative and quantitative characters, linear morphometrics, landmark-based geometric morphometrics, and integumental pore pattern of the cephalothorax. Eucyclops sibiricus sp. nov. from Middle Siberia is described. The two studied species can be considered pseudocryptic; the main morphological difference between the species is the number of setules on the inner side of the first and second exopod segments of the fourth pair of swimming legs: E. sibiricus sp. nov. has 6–10 and 7–17 setules, respectively; E. speratus has 0–3 and 0–6 setules, respectively. The morphometry and integumental pore pattern of the cephalothorax were ineffective for identification and separation of species. The existing previous records of E. speratus were also analyzed, and the records of this species in the Irkutsk region (Russia), as well as in Japan and Korea, are attributed to E. sibiricus sp. nov.

A new species, Diacyclops dyabdar sp. nov. from the Diacyclops crassicaudis (Sars, 1863) species group from northern Middle Siberia, is described. This species is interesting from an ecological point of view, as it lives mainly in watercourses. It is well-distinguished from other species of the group by the presence of spinules on the first segments of the third and fourth pairs of swimming legs, details of the ornamentation on the fourth pair of legs and caudal rami. A detailed comparison of the new species and D. crassicaudis is presented. Molecular markers, including cytochrome c oxidase (COI) of mtDNA and 18S rRNA, ITS1 and ITS2 of nuclear DNA were obtained for a single female of D. dyabdar sp. nov. A morphometric analysis of species and subspecies of the D. crassicaudis group was carried out. It showed slight differences between the described subspecies and some species. On this basis, the subspecies D. crassicaudis, as well as D. iranicus Pesce & Maggi, 1982 and D. fontinalis Naidenow, 1969, are synonymized with the subspecies type. A more precise diagnosis of the D. crassicaudis group is indicated. This group now includes six species. The taxonomic position of several questionable taxa of Diacyclops Kiefer, 1927 described from Iran is discussed: D. landei Mahoon & Zia, 1985; D. bicuspidatus jurenei Najam-un-Nisa, Mahoon & Irfan Khan, 1987; D. landei richardi Parveen, Mahoon & Saleem, 1988 and D. jurenei Parveen, Mahoon & Saleem, 1988. These taxa are accepted as nomen dubium.

Background The control of the Asian tiger mosquito Aedes albopictus (Diptera: Culicidae) is crucial owing to its high vector competence for more than 20 arboviruses—the most important being dengue, chikungunya and Zika virus. Aedes albopictus has an enormous adaptive potential, and its invasive spreading across urban and suburban environments poses challenges for its control. Therefore, all suitable, cost-effective and eco-friendly control tools should be put into practice. In this context, cyclopoid copepods are already known as effective predators of mosquito larvae. This study reports an essential preliminary step towards the integration of copepods into the vector control strategy in Germany, in order to provide a sustainable tool in an integrated control strategy based on the elimination or sanitation of breeding sites, the use of formulations based on Bacillus thuringiensis israelensis ( Bti. ) and the sterile insect technique (SIT). Methods The predatory potential of native cyclopoid copepods, namely the field-derived species Megacyclops viridis (Crustacea: Cyclopidae), was examined against the larvae of Ae. albopictus , and for comparison, against the larvae of the common house mosquito, Culex pipiens sensu lato (Diptera: Culicidae). The use of different larval instars as prey, and various predator-to-prey ratios, were examined under laboratory and semi-field conditions. The compatibility of Bti. applications along with the use of copepods was assessed in the laboratory. Results High predation efficiency of M. viridis upon first-instar larvae of Ae. albopictus was observed under laboratory (up to 96%) and semi-field conditions (65.7%). The copepods did not prey upon stages further developed than the first instars, and in comparison with Ae. albopictus , the predation rates on the larvae of Cx. pipiens s.l. were significantly lower. Conclusions The results indicate a high predation potential of M. viridis against Ae. albopictus larvae, even though strong larval stage and mosquito species preferences were implicated. The integration of copepods as a promising biocontrol agent to the vector control strategy in Germany is therefore highly recommended, especially because of the excellent compatibility of copepods with the use of Bti . However, further research is required, concerning all the probable parameters that may impact the copepod performance under natural conditions. Graphical Abstract

The description of and the record of (Menzel, 1926) from Thailand are presented. The new species is most similar to Watiroyram, Brancelj & Sanoamuang, 2012, the cave-dwelling species described from northern and western Thailand. They share morphological characteristics, such as the free margin of the anal operculum which is ovated and serrate, the same setae and the spines formulae on P1-P4Exp-2 (setae: 5.5.5.4; spines: 3.3.3.3) and Enp-2 of P1-P2, P4 (setae formula 3.4.3) in both sexes. The new species is easily distinguished from due to typical divergent caudal rami, the absence of coxal seta on P1, and the absence of blunt-tipped setae on P2-P3Exp-2. A dichotomous key to the species of group I Lindberg (1953) is proposed.

Thermocyclops Kiefer, 1927, is a genus of Cyclopidae, one of the most diverse families among cyclopoids. To date, 13 species of this genus have been recorded in Thailand. Through intensive sampling of rice fields in central Thailand and temporary waters in northeastern Thailand, one new species, Thermocyclops oryzae sp. nov. , was discovered. This new species is clearly distinguished from other Thermocyclops by the presence of a serrated lobe on the posterior surface of the medial expansion of the basipodite of the fourth swimming leg. Moreover, it can be distinguished from its congeners by (i) ornamentation on the genital double-somite, succeeding two urosomites and caudal ramus; (ii) the length and width ratio of the caudal ramus; (iii) the length ratio of the innermost terminal seta (VI) and the outermost terminal seta (III); (iv) the number of setae on the second endopodal segment of the antenna; (v) projection and ornamentation on the intercoxal sclerites of the first to fourth swimming legs; (vi) the surface ornamentation of the medial margin of the basipodite of the first to fourth swimming legs; and (vii) the relative length of two apical spines of the third endopodal segment of the fourth swimming leg. The present discovery increases the number of species in this genus in Thailand to 14. A pictorial key to all species is proposed, and their ecologies and distributions within Thailand are updated and discussed.

Greece is situated in the East Mediterranean region and in the Balkan peninsula, i.e., a European biodiversity hotspot with high endemism in subterranean and freshwater fauna, highlighting the need to understand its biodiversity. A literature search was undertaken to present a checklist of cladocerans and copepods based on a compilation of published and current data, from 1892 up to 2022 from inland surfaces and subterranean water bodies from different regions of Greece. For Cladocera, 80 species were recorded (9 families with 35 genera). The most diverse families were Chydoridae (20 genera with 33 species) and Daphniidae (5 genera with 27 species). For copepoda, 134 taxa were recorded, in surface water bodies (12 families with 34 genera), subterranean water bodies (7 families with 27 genera), and parasitic copepods (3 families with 3 genera). The most diverse families in surface waters were Cyclopidae (15 genera with 41 taxa) and Diaptomidae (5 genera with 17 species), while those in subterranean waters were Cyclopidae (11 genera with 35 taxa) and Canthocamptidae (6 genera with 17 taxa). More species are expected to be discovered after sampling understudied regions, especially islands, as well as water bodies such as temporary pools, swamps, ditches, puddles, and the littoral parts of lakes, while molecular studies are needed to clarify various cases of complex taxonomy.