Curation and digitization of insect galls in the collection of the State Museum of Natural History Stuttgart

Abstract

Although many natural history collections include gall specimens, a uniform curatorial standard remains to be developed. A subset of the gall collection at the State Museum of Natural History Stuttgart served as a model to examine historical methods of gall preservation and explore digitization of specimen data. Six gall storage methods are compared and critically evaluated based on qualitative assessment of specimen condition. Pinning material in insect drawers is recommended, although preservation on herbarium sheets is best suited for digitization and storage in envelopes is the most space-efficient. A gall digitization method is described. Digitized data were used to generate a map, revealing collecting bias and the existence of underexplored areas in terms of gall diversity. Additionally, the systematic treatment of the gall collection yielded new records for the following species in Baden-Württemberg: Aulacidea hieracii (Bouché, 1834), Cynips agama Hartig, 1840, Diastrophus rubi (Bouché, 1834), Diplolepis nervosa (Curtis, 1838), Phanacis centaureae Förster, 1860, Xestophanes potentillae (Retzius in De Geer, 1783) (Hymenoptera: Cynipidae); Euura pedunculi (Hartig, 1837) (Hymenoptera: Tenthredinidae); Rabdophaga albipennis (Loew, 1850), Rabdophaga degeerii (Bremi, 1847), Rabdophaga heterobia (Loew, 1850), Rabdophaga terminalis (Loew, 1850) (Diptera: Cecidomyiidae); Aphis symphyti Schrank, 1801 (Hemiptera: Aphididae); Livia junci Schrank, 1789 (Hemiptera: Psyllidae); Adelges abietis (L., 1758), Sacchiphantes viridis (Ratzeburg, 1843) (Hemiptera: Adelgidae).