The appearance of wings in insects, early in their evolution [1], has been one of the more critical innovations contributing to their extraordinary diversity. Despite the conspicuousness and importance of wings, the origin of these structures has been difficult to resolve and represented one of the "abominable mysteries" in evolutionary biology [2]. More than a century of debate has boiled the matter down to two competing alternatives-one of wings representing an extension of the thoracic notum, the other stating that they are appendicular derivations from the lateral body wall. Recently, a dual model has been supported by genomic and developmental data [3-6], representing an amalgamation of elements from both the notal and pleural hypotheses. Here, we reveal crucial information from the wing pad joints of Carboniferous palaeodictyopteran insect nymphs using classical and high-tech techniques. These nymphs had three pairs of wing pads that were medially articulated to the thorax but also broadly contiguous with the notum anteriorly and posteriorly (details unobservable in modern insects), supporting their overall origin from the thoracic notum as well as the expected medial, pleural series of axillary sclerites. Our study provides support for the formation of the insect wing from the thoracic notum as well as the already known pleural elements of the arthropodan leg. These results support the unique, dual model for insect wing origins and the convergent reduction of notal fusion in more derived clades, presumably due to wing rotation during development, and they help to bring resolution to this long-standing debate.

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Helius lebanensis sp.n., the oldest representative of the genus Helius Lepeletier & Serville 1828 (Diptera: Limoniidae), from Lebanese amber (Early Cretaceous) is characterized, illustrated and described. A hypothesis of origin and evolution of the genus Helius with association with the Angiosperms is provided and discussed. A complete list of fossil limoniids belonging to Helius is given.

In insects, the ovarian follicular epithelium morphogenesis has been intensively studied and best characterized in the fruit fly, Drosophila melanogaster. It is well established that initially identical somatic follicular cells (FCs) form a simple epithelium overlying the germline cells, but during oogenesis, they diversify into a number of morphologically distinct subpopulations each responsible for creating specific eggshell structures. In addition, some FC subpopulations (e.g. polar cells) are indispensable in establishing antero-posterior and dorso-ventral ovarian follicle axes and patterning of the developing embryo. The morphological and molecular changes that occur during follicular epithelium morphogenesis in Drosophila are frequently considered as a paradigm of the FC diversification in all flies. However, recent comparative studies indicate that, in dipterans, the functioning of the ovarian follicles is diverse, group-specific and may significantly differ from the Drosophila model system. We discuss the similarities and differences of the ovary structure and follicular epithelium morphogenesis in different dipteran groups and put them into a phylognetic context. We suggest that the migratory activity of the FCs represents an evolutionary novelty that evolved in the ancestors of higher dipterans (Brachycera). Subsequently, during evolution of this subgroup, the number of migrating FC subpopulations has gradually increased from one (in Orthorrhapha) to four (in Cyclorrhapha).

A new genus and species of fossil scorpionflies (Mecoptera) Baltipanorpa damzenigen. et sp.n. is described from two well‐preserved male specimens in Baltic amber (middle Eocene: Lutetian). The most characteristic feature of the new taxon is an unusually developed postnotal organ on abdominal tergum IV. This is the most extremely developed example of this organ among Mecoptera and the only observation of notal and postnotal organs among fossil scorpionflies. The following combination of characters are provided to distinguish the new genus from other Panorpidae: Sc, short; R1 and R2 two‐branched; A1 joins posterior margin of wing only at same level as fork of vein Rs; unusual shape of abdomen, abdominal segments I–IV strongly reduced, abdominal segment V elongate and widened, segments VII and VIII strongly elongate; notal and postnotal organs present, strongly developed process (postnotal organ) on tergum IV, unknown in all described extant and fossil scorpionflies. Different types of notal organs of Mecoptera are compared and their function and morphology are discussed. Morphological analysis of notal and postnotal organs in extant species permits us to conclude that B. damzenisp.n. is characterized by the most developed and complex notal organs in all Mecoptera.