Evolution of wing scales in the Diptera

Among the insects with wings clad in scales, the butterflies are most known and show the greatest variety of scales. In the Diptera, only some families or particular genera of two large groups are known to bear scales on wings, i.e., mosquitoes (Culicomorpha) and moth flies (Psychodomorpha). From among another large dipteran group, the crane-flies (Tipulomorpha), the scales on wings are present only in one small genus, Maietta Alexander, now endemic to the southwestern coast of South America. Herewith, we describe the Eocene ancestor of Maietta, embedded in Baltic amber, Maietta (Hoffeinsetta ) christelae, n. subgen., n. sp. This species and its recent congeners document the evolution of scale cover from scarce, restricted only to the anterior portion of the wing, to complete and dense. A similar parallel evolutionary route was previously described in the Culicidae. The fossil representative of Maietta provides also a further example of biogeographical relationships of Baltic fauna with..., All studied specimens are deposited in public institutions. The study was based on an inclusion in Baltic amber (age: Eocene, Lutetian–Priabonian; Grimaldi and Ross 2017) from the private collection of Christel Hoffeins and Hans Werner Hoffeins. The holotype described herein is deposited in the Senckenberg Deutsches Entomologisches Institut (SDEI), Müncheberg, Germany.
Comparative recent specimens: Maietta trimedia Alexander, 1967, Chile, Aysen, 25 km S of Cochuane, 1-2.02.1990, coll. L. E. Peña (housed in ISEA PAS), and the specimens listed in  Santos et al. (2019).
Methods
The specimens were examined with a Nikon (SMZ25) stereomicroscope equipped with a Nikon digital camera (DS-Ri2) at the ISEA PAS. Photographs and drawings were made using a Nikon SMZ 1500 stereomicroscope equipped with a Nikon DS–Fi1 camera at the University of Rzeszów. Usually, 10-30 stacked photographs were combined using Helicon Focus 5.3x64 (Helicon Soft Ltd (c) 2013). The measurements were taken with NIS–Eleme..., The article is descriptive, illustrated with 7 plates of drawings and photos and one table (Table 1). The Table 1 is created based on references, as listed in this table.There are three supplementary files: 1. morphology of the recent and fossil species of Maietta; 2. Phylogeny of the genus Maietta; 3. Climate in Eocene and now in localities of fossil and recent Maietta. No codes and special abbreviations are used.