This study is a revision of the Iberian Merodon Meigen, 1803 species, including an illustrated key, a discussion of taxonomic characters and a morphological diagnosis for all included species. Descriptions are provided for nine new species: M. antonioi sp. n., M. arundanus sp. n., M. cabanerensis sp. n., M. crypticus sp. n., M. hurkmansi sp. n., M. legionensis sp. n., M. longispinus sp. n., M. luteihumerus sp. n. and M. quercetorum sp. n. The taxon M. escorialensis Strobl, 1909 is redescribed and lectotype is designated. Lectotypes are designated for four taxa: M. albifrons Meigen, 1822; M. spinipes obscuritarsis Strobl in Czerny & Strobl, 1909; M. spicatus Becker, 1907; and M. spinipes grossus Gil Collado, 1930. Three varieties are redefined and considered as valid species: M. obscuritarsis Strobl in Czerny & Strobl, 1909 (as var. of spinipes); M. grossus Gil Collado, 1930 (as var. of spinipes); M. unicolor Strobl in Czerny & Strobl, 1909 (as var. of aeneus). The following new synonymies are proposed: M. affinis Gil Collado, 1930 syn.n. (= junior synonym of M. longicornis Sack, 1913); M. lusitanicus Hurkmans, 1993 syn.n. (= junior synonym of M. serrulatus Wiedemann in Meigen, 1822); M. andalusiacus Paramonov, 1929 syn.n., M. bolivari Gil Collado, 1930 syn.n., M. hispanicus Sack, 1931 syn.n. (= all three are junior synonyms of M. unguicornis Strobl in Czerny & Strobl, 1909); M. spicatus Becker, 1907 syn.n. (= junior synonym of M. chalybeus Wiedemann in Meigen, 1822); M. fuerteventurensis Barkemeyer, 2002 syn. n. (= junior synonym of M. obscuritarsis Strobl, 1909); and M. spinipes grossus (Gil Collado, 1930) syn.n. (= junior synonym of M. albifrons Meigen, 1822). Status of M. serrulatus Wiedemann in Meigen, 1822 is revised. Four species: M. longicornis Sack, 1913, M. pumilus Macquart, 1849, M. ottomanus Hurkmans, 1993 and M. segetum (Fabricius, 1794) are new for the Iberian Peninsula. Male genitalia are illustrated for all the species and a key of the 34 Iberian species (+ M. hurkmansi sp. n.) for males and females (except for the unknown female of M. longispinus sp. n.) is appended. Distribution and biological data for the Iberian species are also included. A brief zoogeographic discussion is also presented. The level of endemism of genus Merodon on the Iberian Peninsula is extremely high (almost 50%).

Study of specimens of Merodon Meigen collected in southwestern Europe resulted in new data and taxonomic changes for this genus. The cryptic species Merodon confusussp. nov. (Merodon equestris species group) is described based on specimens collected in Cabañeros National Park, central Spain. Morphological and molecular diagnostic characters are provided to separate members of the species group. Merodon aeneus fulvus Gil Collado is proposed as a junior synonym of Merodon pumilus Macquart. The first Iberian record of Merodon rufus Meigen is reported and updates of the revision of Iberian Merodon are provided.

Trying to unravel Darwin's entangled bank further, we describe the architecture of a network involving multiple forms of mutualism (pollination by animals, seed dispersal by birds and plant protection by ants) and evaluate whether this multi-network shows evidence of a structure that promotes robustness. We found that species differed strongly in their contributions to the organization of the multi-interaction network, and that only a few species contributed to the structuring of these patterns. Moreover, we observed that the multi-interaction networks did not enhance community robustness compared with each of the three independent mutualistic networks when analysed across a range of simulated scenarios of species extinction. By simulating the removal of highly interacting species, we observed that, overall, these species enhance network nestedness and robustness, but decrease modularity. We discuss how the organization of interlinked mutualistic networks may be essential for the maintenance of ecological communities, and therefore the long-term ecological and evolutionary dynamics of interactive, species-rich communities. We suggest that conserving these keystone mutualists and their interactions is crucial to the persistence of species-rich mutualistic assemblages, mainly because they support other species and shape the network organization.

The Old World syrphid genus Merodon Meigen 1803 is highly species-diverse and has a significant number of endemic species in the circum-Mediterranean area. The present study reports on taxonomic changes resulting from the examination of adult Merodon specimens collected in 15 Turkish provinces during the period 1992 to 2002, and provides new faunistic data. Merodon ilgazense n. sp. is described. Four species of Merodon new to Turkey are recorded: M. armipes Rondani 1843, M. auronites Hurkmans 1993, M. bessarabicus Paramonov 1924 and M. chalybeatus Sack 1913. Lectotypes are designated for two taxa: M. chalybeatus Sack 1913 and M. clunipes Sack 1913. Merodon italicus Rondani 1845 rev. stat. is reinstated as a valid species. Following a detailed study of the type material in different entomological collections, the status of 10 taxa is revised and five new synonymies are proposed: M. albonigrum Vuji Radenkovi & S˘imi 1996 n. syn. (=junior synonym of M. chalybeatus Sack 1913); M. alexeji Paramonov 1925 n. syn. (=junior synonym of M. serrulatus Wiedemann in Meigen 1822); M. aureotibia Hurkmans 1993 n. syn. (=junior synonym of M. vandergooti Hurkmans 1993); M. kaloceros Hurkmans 1993 n. syn. (=junior synonym of M. erivanicus Paramonov 1925); M. longicornis Sack 1913 n. syn. (=junior synonym of M. italicus Rondani 1845).