RESUMEN
Ponds are common freshwater habitats in the European landscape that substantially contribute to local and regional biodiversity. Chironomids often dominate invertebrate communities in ponds but are usually disregarded in ecological studies due to relatively complicated taxonomy and identification issues. We present a comprehensive overview of the chironomid diversity in 246 ponds spanning a wide range of conditions extending from the Pannonian Plain to the Carpathians. Altogether, we recorded 225 taxa including 192 species from six subfamilies (Podonominae, Tanypodinae, Diamesinae, Prodiamesinae, Orthocladiinae and Chironominae). However, the chironomid taxa inventory is far from complete and about 16% of the total diversity of pond-dwelling chironomids remains undetected. Chironomid alpha diversity showed a significant unimodal pattern along the elevation gradient with the highest number of taxa per pond expected around 790 m a.s.l. Gamma diversity also peaked in mid-elevations (600-800 m), and the common chironomid taxa partitioned the 2100-m long altitudinal gradient relatively evenly. The heterogeneity of chironomid communities among ponds measured as beta diversity was significantly higher in elevations below 800 m. Temperature and the proportion of surrounding forests significantly influenced alpha diversity of chironomid communities, while urban land cover and pond size had no significant effect. Ponds with a mean annual air temperature of approximately 4.8°C and a low proportion of surrounding forests are expected to harbour the most diverse chironomid communities. Our study showed that chironomids represent a very diverse and often exceptionally rich group of pond-dwelling macroinvertebrates. Given the high diversity and broad range of occupied niches, chironomids should not be overlooked in pond ecology studies. On the contrary, they should be considered a potential model group.
RESUMEN
In this paper we revise the chordeumatidan genus Haasea Verhoeff, 1895 for the first time and describe two new species viz., H. gruberi sp. nov. and H. makarovi sp. nov. discovered in Austria and Serbia, respectively. A new terminology is proposed to standardize the description of the gonopod structures in the genus. Type material obtained from several institutions was examined and documented herein, whereby lectotypes are designated. We clarified the taxonomic status of a few taxa and consider the species H. norica (Verhoeff, 1913) and H. guidononveilleri Makarov, 2008 as a junior subjective synonyms of H. cyanopida (Attems, 1903) and H. vidinensis (Strasser, 1973a), respectively. The following subspecies or varieties, viz., Orobainosoma filicis ossiacum Verhoeff, 1939b, Orobainosoma flavescens vornatscheri Verhoeff, 1935, Orobainosoma hungaricum orientale Tabacaru, 1965, and Orobainosoma inflatum var. aspidiorum Verhoeff, 1929 are here regarded as junior subjective synonyms of their nominal taxa. The taxonomic relationships within the genus Haasea are discussed and an identification key to its 17 species is presented, based on number of body segments and gonopod structures. Maps showing species occurences based on historical and recent records are presented to understand their respective geographic ranges. H. flavescens is now deleted from the list of species in Croatia, Bosnia and Herzegovina, Slovenia and Italy as these records were based on misidentified material. H. inflata is deleted from the fauna of Bosnia and Herzegovina, whereas H. hungarica is newly recorded from Austria, Serbia and Slovenia.