Rarefied gas flow in microtubes at low Reynolds numbers

U radu se proučava osnosimetrično, izotermsko, stišljivo strujanje gasa sa klizanjem, pri malim vrednostima Rejnoldsovog broja. Problem je rešen primenom jednačine kontinuiteta i Navije-Stoksovih jednačina, zajedno sa Maksvelovim graničnim uslovom prvog reda. Analitički rezultati su dobijeni primenom perturbacione metode. Dobijena rešenja se dobro slažu sa poznatim eksperimentalnim rezultatima drugih autora.Low Reynolds number, axisymmetric, isothermal, compressible, slip gas flow in microtubes is investigated in this paper. The problem is solved by the continuum equations, continuity and Navier-Stokes, along with Maxwell first order boundary condition. The analytical results are obtained by perturbation method. The solutions show a good agreement with experimental results

CORRECT CITATIONS OF THE RECENTLY DESCRIBED SPECIES OF GENERA MERODON, CHEILOSIA AND PARAGUS (DIPTERA: SYRPHIDAE)

The paper cites the correct citation of 14 species described in 2020, which are also listed in the Atlas of the Hoverflies of Greece. In order to prevent potential dilemmas and different taxonomic interpretations in accordance with the rules of the International Commission on Zoological Nomenclature, it is stated that 14 presented species should be cited

Rarefied gas flow in microtubes at low Reynolds numbers

U radu se proučava osnosimetrično, izotermsko, stišljivo strujanje gasa sa klizanjem, pri malim vrednostima Rejnoldsovog broja. Problem je rešen primenom jednačine kontinuiteta i Navije-Stoksovih jednačina, zajedno sa Maksvelovim graničnim uslovom prvog reda. Analitički rezultati su dobijeni primenom perturbacione metode. Dobijena rešenja se dobro slažu sa poznatim eksperimentalnim rezultatima drugih autora.Low Reynolds number, axisymmetric, isothermal, compressible, slip gas flow in microtubes is investigated in this paper. The problem is solved by the continuum equations, continuity and Navier-Stokes, along with Maxwell first order boundary condition. The analytical results are obtained by perturbation method. The solutions show a good agreement with experimental results

The fauna of hoverflies (Diptera: Syrphidae) of Vojvodina province, Serbia

Many hoverfly species of faunal and zoogeographical interest are found in Serbia's northern province of Vojvodina due to the diversity of its biotopes. In this paper, the presence of 252 species of hoverflies (Diptera: Syrphidae) from 69 genera is documented. Five species are here recorded for the first time in Serbia: Anasimyia contracta Claussen & Torp Pedersen, 1980; Anasimyia transfuga (Linnaeus, 1758); Eristalinus megacephalus (Rossi, 1794); Helophilus hybridus Loew, 1846; and Mallota fuciformis (Fabricius, 1794). One species is recorded for the first time in Vojvodina: Cheilosia brunnipennis (Becker, 1894). The records of 12 species from Vojvodina Province are the only ones on the Balkan Peninsula, while the records of 15 species are the only ones in Serbia

Taxonomic revision of the afrotropical genus <i>Megatrigon </i>Johnson, 1898 (Diptera: Syrphidae)

The genus-group taxon Megatrigon Johnson, 1898, stat. nov., is revised and treated as a valid genus within the Merodontini (= Eumerini). Extensive diagnoses are given for the genus and for its three constituent species groups: argenteus group [11 spp.], nivalis group [monotypic], sexfasciatus group [3 spp.]. Five new generic combinations are proposed within Megatrigon: M. argenteus (Walker, 1852) comb. nov., M. flavimarginatus (Hull, 1964) comb. nov., M. jacobi (Hervé-Bazin, 1913) comb. nov., M. nivalis (Hull, 1964) comb. nov. and M. ochreatus (Hull, 1964) comb. nov. All species of the argenteus group are revised and nine new species are described: Megatrigon apiformis sp. nov., M. argentifrons sp. nov., M. argentimaculatus sp. nov., M. cooksoni sp. nov., M. immaculatus sp. nov., M. magnicornis sp. nov., M. natalensis sp. nov., M. sexmaculatus sp. nov., M. tabanoides sp. nov. Within the sexfasciatus group, M. jacobi (Hervé-Bazin, 1913) comb. nov. is treated as a senior synonym of Eumerus connexus Hull, 1964 syn. nov., but no further work is done at the species level due to insufficient material

A new European species of genus Eristalis Latreille, 1804 (Diptera: Syrphidae)

Eristalis tecta sp. n. is described, based on material from the Macedonian Museum of Natural History (Skopje, Macedonia, former Republic of Yugoslavia). This species is closely related to E. interrupta (Poda, 1761). Diagnostic characters of the species, together with figures of the male terminalia, are given. A checklist ofthe Eristalis species known from the Balkan Peninsula is presented

New data on hoverfly diversity (Insecta: Diptera: Syrphidae) of the special nature reserve the Obedska bara marsh (ramsar site in Serbia)

Hoverflies are well-investigated insects group on Obedska bara Marsh due to long-term investigations carried out by a scientific team from Faculty of Sciences, University of Novi Sad, Serbia (Vujić et al., 1998). After 15 years, monitoring of biodiversity in this Ramsar site is continued by scientific project 1770 of Ministry of Science and Environmental Protection Republic of Serbia. Based on new investigations and current nomenclature changes, the following results were obtained: record of Eupeodes goeldlini Mazánek, Láska et Bičik, 1999 is the first for Serbia, nine species were recorded for the first time for Obedska bara Marsh, seven species were replaced by recently established junior synonyms and three were excluded from the faunal list of Obedska bara Marsh. These data complete the list of 93 hoverfly species registered on Obedska bara Marsh

NEW DATA ON THE GENUS SYRPHUS FABRICIUS, 1775 (DIPTERA: SYRPHIDAE) FROM THE BALKAN PENINSULA INCLUDING THE FIRST RECORD OF SYRPHUS NITRIDIFRONS BECKER, 1921

Four species of the genus Syrphus Fabricius, 1775 have been recorded in the Balkan Peninsula: S. nitidifrons Becker, 1921, S. ribesii (Linnaeus, 1758), S. torvus Osten Sacken, 1875 and S. vitripennis Meigen, 1822. The first documented record of S. nitidifrons from the Balkan Peninsula is provided, as well as keys for both males and females, lists of material examined and distribution maps for each Balkan Syrphus species. Syrphus torvus is new to Croatia. All the studied taxa are widespread throughout the Balkans, except S. nitidifrons, limited to a few mountain localities: Kopaonik Mountain (Serbia), Jahorina Mountain (Bosnia and Herzegovina) and Durmitor Mountain (Montenegro). The need for conservation of S. nitidifrons is remarked

NEW FINDINGS OF HOVERFLY FAUNA (DIPTERA: SYRPHIDAE) OF THE WESTERN PART OF SERBIA (ZLATIBOR AND RAŠKA DISTRICTS)

During a three year systematic sampling of the hoverfly fauna in highlands of western Serbia, 150 hoverfly species of 51 genera were recorded for this region. Eumerus ovatus Loew, 1848, new to the fauna of Serbia, was recorded on mountain Zlatibor. Additionally, 4 new hoverfly species from the genus Merodon Meigen, 1803 were found, awaiting species descriptions. The most species-rich areas in the investigated region are SW part of Mt. Golija and SE part of Mt. Zlatar. These mountains also have the highest number of protected and strictly protected species. In order to preserve this high local diversity of hoverflies, protection of these areas, as well as proper conservation management are of crucial importance

MERODON NATANS AND M. PULVERIS (DIPTERA: SYRPHIDAE): DELIMITATING CRYPTIC HOVERFLY SPECIES USING THE GEOMETRIC MORPHOMETRIC METHOD

A landmark-based geometric morphometric method was employed to delimitate two morphologically closely-related species of the hoverfly Merodon natans species group based on wing parameters. The studied species, Merodon natans and M. pulveris, were successfully determined using this method. Analyses revealed a significant difference in wing size and shape between individuals of the two species, thereby proving that these are two distinct species, even though, morphologically very similar. Discriminant and cluster analyses also uncovered a subtle difference in wing shape between M. pulveris populations, indicating intraspecific differentiation with potential conservation implications. The results of the morphological study were supplemented with known distribution data of the investigated species