Arenopontia (Neoleptastacus) huysi, sp. nov. (Crustacea, Copepoda, Harpacticoida) from marine interstitial of Montenegro (S.E. Europe)

A new species of Arenopontia (Neoleptastacus) is described on the basis of a single female collected from one sandy beach in Montenegro, Adriatic Sea. With the addition of the new species, the subgenus Neoleptastacus now includes 18 species throughout the world. At the end of this paper there is a key for their determination. Received: 20 March 1999 / Received in revised form: 15 September 1999 / Accepted: 21 September 1999     

New Harpacticoida (Crustacea, Copepoda) from the North Atlantic Ocean. V. Three New Species of Metahuntemannia Smirnov (Cletodidae)

Metahuntemannia triarticulata sp.n., M. arctica sp.n. and M. bifida sp.n. arc described. M. triurficulata and M. arctica belong to the 'spinosa' group within the genus Metahuntemannia Smirnov. From the closely related species, M. triarticulata differs in the possession of 3-segmented Enp P3, M. arctica in the segmentation of the Al, and both new species in the setation of their swimming legs P1–P5. M. hifida belongs to the 'talpa' group within Metahuntemannia and differs from the closely related species in the setation of the swimming legs P2–P4. The species relationships and the phylogeny within the genus are discussed. All species were collected at the Iceland-Faroe Ridge from depths between 435 and 2500 m.     

Some Crustacea Copepoda from Venezuela

The study of 38 samples of aquatic fauna from Venezuela increased the number of known species here from 28 to 66. Fifteen new species for science are described. A list of Copepoda known from the other regions of South America is presented. From this list, it can be said that only 50% of the inland water Copepoda living actually in Venezuela are known.     

On Neodiaptomus schmackeri (Poppe & Richard, 1892) (Crustacea,Copepoda)

Neodiaptomus schmackeri and related species are redescribed. The synonymy of this species with N. strigilipes and N. handeli is discussed.     

Some Freshwater Cyclopoids (Crustacea: Copepoda) of the Island of Soqotra (Indian Ocean), with the Description of Three New Species

Copepods from Soqotra Archipelago, a largely unstudied microplate in the north‐west Indian Ocean, were investigated. Seven species of six cyclopoid genera: Ectocyclops Brady , 1904; Halicyclops Norman , 1903; Mesocyclops Sars , 1914; Microcyclops Claus , 1893; Paracyclops Claus , 1893 and Tropocyclops Kiefer , 1927 were identified. Three of them are new to Science, viz. Mesocyclops wraniki sp. n., Halicyclops soqotranus sp. n., and Ectocyclops mozhae sp. n. They are described and figured.     

Molecular phylogeny of the Calanoida (Crustacea: Copepoda)

The order Calanoida includes some of the most successful planktonic groups in both marine and freshwater environments. Due to the morphological complexity of the taxonomic characters in this group, subdivision and phylogenies have been complex and problematic. This study establishes a multi-gene molecular phylogeny of the calanoid copepods based upon small (18S) and large (28S) subunits of nuclear ribosomal RNA genes and mitochondrial encoded cytochrome b and cytochrome c oxidase subunit-I genes, including 29 families from 7 superfamilies of the order. This analysis is more comprehensive than earlier studies in terms of number of families, range of molecular markers, and breadth of taxonomic levels resolved. Patterns of divergence of ribosomal RNA genes are shown to be significantly heterogeneous among superfamilies, providing a likely explanation for disparate results of previous studies. The multi-gene phylogeny recovers a monophyletic Calanoida, as well as the superfamilies Augaptiloidea, Centropagoidea, Bathypontioidea, Eucalanoidea, Spinocalanoidea and Clausocalanoidea. The phylogeny largely agrees with previously-published morphological phylogenies, including e.g., enlargement of the Bathypontioidea to include the Fosshageniidae.     

The diminution of heterochromatic chromosomal segments in Cyclops (Crustacea,Copepoda)

The chromosomes of Cyclops divulsus, C. furcifer, and C. strenuus, like those of several other Copepods, undergo a striking diminution of chromatin early in embryogenesis. The process is restricted to the presumptive soma cells and occurs at the 5th cleavage in C. divulsus, at the 6th and 7th in C. furcifer, and at the 4th in C. strenuus. The eliminated chromatin derives from the excision of heterochromatic chromosome segments (H-segments). Their chromosomal location is different in the three investigated species: Whereas in C. divulsus and C. furcifer the H-segments form large blocks — exclusively terminal in the former and terminal as well as kinetochoric in the latter — the germ line heterochromatin in C. strenuus is scattered all along the chromosomes. Extensive polymorphism exists with respect to the length of the terminal H-segments in C. furcifer, and with respect to the overall content of heterochromatin in the chromosomes of C. strenuus. In a local race of C. strenuus an extreme form of dimorphism has been found which is sex limited: females as a rule are heterozygous for an entire set of large (heterochromatin-rich), and a second set of small chromosomes in their germ line. Males are homozygous for the large set. In the first three cleavage divisions the H-polymorphism is solely expressed through differences of chromosome length. Following diminution the differences between homologous have disappeared. Feulgen cytophotometry demonstrates that in the three species the 1C DNA value for the germ line, as measured in sperm, is about twice that measured in somatic mitoses (germ line/soma C-values in picograms of DNA: C. strenuus 2.2/0.9, C. furcifer 2.9/1.44, C. divulsus 3.1/1.8). — The data imply that chromatin diminution is based on a mechanism which allows specific DNA segments, regardless of their location and size, to be cut out from the chromosomes without affecting the structural continuity of the remaining DNA. This mechanism may be analogous to that of prokaryotic DNA excision.     

The freshwater Calanoida (Crustacea: Copepoda) of Thailand

14 Species of freshwater Calanoida in Thailand are reported in this study. The most common species is Neodiaptomus botulifer. Most of these belong to the Southeast Asian species, the remainder are either Indian or East Asian copepods. The zoogeographical demarcation of copepods in Thailand is not very distinct due to its interconnecting riverine and reservoir systems as well as frequent flood. The peculiarity of the Thai Calanoida and their distribution is discussed in a Southeast Asia context. A taxonomic key to the Thai Calanoida is formulated.     

Energy budget of the female harpacticoid Tisbe carolinensis (Copepoda,Crustacea)

Partitioning of the ingested energy in harpacticoid Tisbe carolinesis was investigated with ¹⁴C labelled diatom Cylindrotheca sp. (Strain N-1) as food source under laboratory conditions (salinity 30 ppt, 24 ± 1.5°C). Over a 24 hr period, egg sacs and fecal pellets produced per T. carolinesis were 0.64 and 1.19, respectively. Radioactivity measured in the body accounted for 49.1% of the ingested radioisotope, whilst 42.3% of the energy was channneled into reproduction. Respiration and excretion took up 4.9% of the energy and the rest, 3.7%, went into fecal pellets.     

Mesocyclops (Crustacea, Copepoda, Cyclopidae) in the South Pacific islands

Based mainly on recently collected material, we discuss the taxonomy and zoogeography of a (sub)tropical genus, Mesocyclops, in the South Pacific. A new species, Mesocyclops roberti sp. nov. is described from Fiji and the Wallis Islands. New data on the geographic distribution and morphology are reported for Mesocyclops medialis, Mesocyclops woutersi and Mesocyclops aspericornis. Phylogenetic reconstructions coding the intraspecifically variable characters by three different methods (unordered, unscaled and scaled coding) support close relationship of M. roberti with two Australian species (Mesocyclops brooksi and Mesocyclops notius). Both the “unordered” and “scaled” analyses show monophyly of a group composed of Australian (Mesocyclops australiensis, M. brooksi, M. notius, and Mesocyclops pubiventris) and South Pacific (M. medialis and M. roberti sp. nov.) taxa. None of the analyses supports a sister relationship of M. roberti with M. medialis (New Caledonia, Vanuatu), the only other species restricted to South Pacific, which suggests that Mesocyclops invaded the South Pacific from Australia at least twice. The sister relationship of the Australian-South Pacific clade remains unresolved, yet all reconstructions suggest a link with Asian Mesocyclops sp.     

Chromosomal radiosensitivity as associated with chromatin diminution in cyclops (Crustacea,Copepoda)

Chromosomal radiosensitivity inferred from the yield of chromosome aberrations (CAs) was for the first time studied in Cyclops (Crustacea, Copepoda) before and after chromatin diminution (CD). A comparison was made for C. kolensis, in which CD denudes somatic embryo cells of the greatest (94%) DNA amount known for multicellular organisms, and C. insignis, which lacks CD. The two species have similar genome sizes, 4.6 and 4.3 pg. respectively. Radiosensitivity of C. kolensis chromosomes proved to be extremely high during prediminution cleavage divisions. This was attributed to membrane damage in granules that contain enzymes (topoisomerases) normally involved in cleavage and ligation of chromosomal DNA during CD.     

Achiasmatic meiosis and complex heterozygosity in female cyclopoid copepods (Copepoda,Crustacea)

In Mesocyclops edax S.A. Forbes, 2n=14, a North American copepod, the females are heterozygous for several interchanges leading to the formation of large rings of chromosomes (rings of 14, or of 12 plus 1 bivalent) at meiotic metaphase, comparable to those of the plant Oenothera, although no chiasmata are present. The chromosomes are more or less metacentric and have large terminal H-segments. In the rings homologous arms are held together by connecting fibers which insert close to the euchromatin-heterochromatin junctions. Coordinated orientation of the zigzag type seems to be the role.     

A new species of Metacyclops from a hyporheic habitat in North Vietnam (Crustacea,Copepoda, Cyclopidae)

A new species of Metacyclops is described from hyporheic waters and small rock depression with leaf litter in North Vietnam, the Tam Đao Mountains). Metacyclops amicitiae sp. n. can be distinguished from its congeners by the unique combination of the following characters: 12-segmented antennule, distal segment of P4 endopodite bearing a single apical spine, and the surface ornamentation of the intercoxal sclerites in P1–P4 (pilose on the distal margin of P1-P4 and spinulose on the caudal surface of P4). The latter character separates the new Metacyclops from its closest relative, Metacyclops ryukyuensis, known only from the Ryukyu Islands (Ishigaki). The genus Metacyclops with the new species described herein is also for the first time recorded from Vietnam. An identification key is provided to the south and east Asian species of the genus.     

Freshwater Crustacea (Cladocera,Copepoda) of Iceland: taxonomy,ecology, and biogeography

Of the many types of freshwater bodies across Iceland (e.g., lakes, springs, rivers, and ponds), greater effort has been invested in researching the freshwater Crustacea (Cladocera, Copepoda) of more permanent, larger, and deeper water bodies than on smaller or more ephemeral sites. To address this, we described the fauna of 12 shallow freshwater bodies distributed from the coast to the central highlands of Iceland. We identified 16 species in 11 genera belonging to six families of Cladocera, and 12 species in eight genera belonging to four families of Copepoda. Five of the species we identified (Alona werestschagini, Cyclops vicinus, Daphnia cristata, Diacyclops abyssicola, and Heterocope borealis) represent new distribution records for Iceland, increasing the number of species now known from this region to 34 Cladocera and 38 Copepoda taxa. Additionally, we discuss the taxonomy of some species with doubtful taxonomical status. Six crustacean taxocenes are described, each characterized by the dominance of different taxa, with bottom sediment characteristics best explaining species assemblage structure. We evaluated the relationships between Icelandic Cladocera and Copepoda faunas and those of the adjacent Svalbard, Faroe, and Shetland Islands, Greenland, and the mainland Norway. The taxonomic composition of the Icelandic fauna is dominated by widely distributed Holarctic, and secondarily Palaearctic and Nearctic species, and is more similar to the faunas of the major North Atlantic islands (64.2–71.8 % similarity) than it is to that of continental Norway.     

New Harpacticoida (Crustacea, Copepoda) from the North Atlantic Ocean. VI. Eight New Species of the Genera Paranannopus Lang and Cylindronannopus Coull (Cletodidae)

Paranannopus trisetosus sp.n., P. singulosetosus sp.n., P. denticulatus sp.n., P. uniarticulatus sp.n., P. variabilis sp.n., P. kunzi sp.n. and Cylindronunnopus bispinosus sp.n. are described and classified to the three evolutionary groups within the genus Paranannopus. P. variabilis, P. kunzi and P. hicksi belong to the first evolutionary group with Enp P2-P4 3:3:2-segmented. All three species differ from each other and the closely related species in the setation of the swimming legs P1-P5 and to some extent in the segmentation of the Al. P. trisetosus belongs to the second group with Enp P2-P4 2-segmented, and it differs from the closely related P. atlanticus Coull in the setation of the segment 2 Exp P1, P4 and of the P5. P. singulosetosus, P. uniarticulatus and P. denriculutus represent the third evolutionary group with at most I-segmented Enp P2-P4. They differ from each other in the segmentation of the Enp P2-P4 and the setation of the swimming legs P2-P4 and to some extent in the segmentation of the Exp A2. Cylindronunnopus bispinosus differs from the closely related species C. elongatus (Becker et al. ) comb.n. in the setation of the P5. Updated keys are given for both genera. All species were collected at the Iceland-Faroe Ridge from depths between 435 and 2500 m.     

On the foraging and feeding ability of Oithona davisae (Crustacea,Copepoda)

Growth experiments with macrophytes revealed anomalies in the growth and development of Najas intermedia. Further analyses showed that these anomalies were caused by differences between the male and female plants. To examine the gender-related differences, the results of two field experiments and a phenological monitoring programme were analysed. The field experiments were conducted in four different lakes in Southern Germany. Over the course of 2 years, eight different sediments were used to research the interaction between the gender and the growth of N. intermedia plants. The phenological monitoring programme, on the other hand, was focused on the development of three different populations of N. intermedia in three Southern German lakes. The results of the experiments revealed significant differences in the gender-related development: Depending on the environmental conditions, male plants grew between 20 and 40% faster than female plants. Additionally, the male plants developed flowers earlier in the vegetation period and died before the female plants. As a result, male and female plants coexisted in the same lake only for a short period of time. This might be a strategy to reduce the competitive pressure between the genders and to gain an advantage over rival species.