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Detection of morphologically indistinguishable cryptic species implies using an integrative taxonomic approach with a combination of molecular, contemporary morphological, ecological and other relevant analyses. Within a contemporary morphological analysis, two approaches are commonly used in hoverfly taxonomy: a geometric morphometric analysis of the wing and surstyle shape. Here, the importance of the R4+5 vein shape is tested in cryptic species delimitation within four Merodon species groups using linear and semilandmark geometric morphometric analyses. As expected, geometric morphometrics showed a stronger resolution compared to linear morphometrics. Linear morphometrics failed to detect differences related to sexual dimorphism or differences among the species M. pruni and M. obscurus. However, all cryptic species and sexes were separated with high significance based on the R4+5 vein shape. Moreover, obtained results concurred with the landmark-defined wing shape and molecular results published in previous studies. Additionally, combining two characters, the semilandmark R4+5 vein shape and the landmark-defined wing shape, provided more detailed and precise insights into the shape differences. Our results showed that the R4+5 vein shape stands out as an important character in species delimitation of hoverflies where the sinuation of this vein is present. Therefore, it can be beneficial as a single character or in combination with a landmark-based wing shape analysis.

In the present work, the Afrotropical species of the bombiformis species group, part of the aureus lineage, are revised. Six species are recognized, based on a combination of morphological and genetic features. Three of these species are new to science: Merodon lotus Vujić & Radenković sp. nov., M. vittatus Vujić & Likov sp. nov., and M. zebra Vujić & Radenković sp. nov. Redescriptions are provided for the other three species: M. bombiformis Hull, 1944, M. multifasciatus Curran, 1939, and M. nasicus Bezzi, 1915. The female of M. bombiformis is described. The name Merodon edentulus Macquart, 1855 is considered here as a nomen dubium. One new synonymy is proposed: M. apimima Hull, 1944 syn. nov. (junior synonym of M. multifasciatus). The distribution of the bombiformis species group is discussed. The larval host plant of M. multifasciatus is identified as Gladiolus. A key to the identification of both males and females of the bombiformis group is provided.