The hoverfly genus Parhelophilus Girschner, 1897 in Europe consists of three widespread species, Parhelophilus consimilis (Malm, 1863), Parhelophilus frutetorum (Fabricius, 1775) and Parhelophilus versicolor (Fabricius, 1794), and a fourth species of more restricted range, Parhelophilus crococoronatus Reemer, 2000 (Speight 2020). This latter species has only been found in some localities of South-Western Europe, specifically in France and Portugal (Reemer, 2000; van Eck, 2016). Three Parhelophilus species are reported from Spain. Parhelophilus versicolor is the most commonly collected species, while P. consimilis has been reported only from Mallorca island and P. frutetorum from Barcelona province (Ricarte & Marcos-García, 2017).

The aim of the present paper is to update the Iberian knowledge of this hoverfly genus which is specifically linked to wetlands and marshlands.

Syrphidae adults were collected using hand nets. In 2002 the area around the bird hides close to the La Rocina Visitors Centre, El Rocío, in the Coto de Doñana area were visited. In 2003, on the way to the Sierra de Alcaraz, a new dam construction site was visited, which had a flooded forested area with a large pool with decaying shrubs and dead trees (Figs 1–2). This was part of the newly built “Presa de la Risca”, in the Murcia province (Segura Hydrographic Confederation, 2020). In 2021, the Phragmites-rich natural wetland ‘Lagunas de Padul’, in Granada province, was shortly visited in the framework of the ‘Fauna Ibérica’ project of Eristalinae (see acknowledgements). The species were identified with Van der Goot (1981) and Reemer (2000).

The material is deposited in the following collections: JSA - private collection of Jeroen van Steenis, Amersfoort, the Netherlands; CEUA-CIBIO - collection, University of Alicante, Spain; WSB - private collection of Wouter van Steenis, Breukelen, the Netherlands.

The photos for the adult figures were taken with a Canon EOS D6 camera, Canon MP-E 1-5× macrozoom lens and a Yongnuo YN14EX ring flash placed on a Cognisys Stack-Shot macrorail. Several photos were combined with the stacking software Zerene Stacker 1.04 and processed with the image manipulating programme GIMP 2.8.14. Female photos were produced as stacks of individual images made with a camera (Leica DFC 450) attached to a binocular stereomicroscope (Leica M205 C). Stacks were made in Leica Application Suite X (LAS X) ^®, ver. 3.0.4.16529. The map was produced in Google Earth Pro 2021.

The here presented records of Parhelophilus crococoronatus are the first from Spain, although the previous records from Portugal and France made the occurrence in Spain likely. The female reported from Granada is the second known to this species and confirms the variability of certain characters used as diagnostic to separate this from other Parhelophilus species.

The reported finding of Parhelophilus frutetorum at the CEUA-CIBIO collection confirms the presence of this species in Spain, which was known only from an old record of the nineteenth century (Ricarte & Marcos García, 2017). The new material of P. versicolor provides the first evidence of this species to occur in Murcia and Granada provinces, both in the southern half of the Iberian Peninsula. In addition, the re-identification of the specimen of P. versicolor from León that turned out to be P. frutetorum implied that P. versicolor is deleted from the list of species recorded from León province and, in its place, P. frutetorum is added to the hoverfly inventory of this province.

The habitat in which Parhelophilus crococoronatus was collected in Murcia is most likely destroyed by the flooding of the river valley in which it was collected as most of the drowned vegetation will have been totally decayed by now. The building of a hydro dam in 2002 flooded the area creating a temporary pool with decaying shrubs and trees formerly found in the river valley. The low water level with plenty of decaying vegetation formed a very suitable habitat for this species larvae. In the course of several years, the valley flooded more and more and the decaying vegetation is likely completely submerged and gone (Segura Hydrographic Confederation, 2020). The building of hydro dams has proven to reduce the quantity and quality of wetland areas (Talukdar & Pal, 2017; Zheng et al., 2019) and in this view the presence of P. crococoronatus in the ‘Embalse de la Risca’ is doubtful at present. Nonetheless, the other records (e.g. Granada) suggest that there might be other viable populations of this species throughout Spain, however a better understanding of the current occurrence of the species in Spain is necessary.

The habitat degradation is one of the many threats for the survival of Syrphidae (Ivošević et al., 2021) and hydro dam construction is considered as one of these specific threats for hoverfly biodiversity. Especially in the dry and vulnerable Mediterranean Region, this could lead to the extinction of many species depending on small streams and its specialised flora and fauna (Baffert & Bauer, 2020). Nonetheless, the artificially-generated accumulation of decaying and dead vegetation in the early stage of the dam flooding could have increased the suitable habitat for Parhelophilus larvae temporarily, which needs to be confirmed.

Liesbeth Bakker (Breukelen, The Netherlands) and Menno van Zuijen (Wageningen, The Netherlands) are acknowledged for their company during the fieldwork in the years 2002 and 2003 respectively, and Iván Ballester Torres, Pablo Aguado Aranda and Zorica Nedeljković for their participation in the 2021 fieldwork in the Lagunas de Padul, Granada. Martin Hauser (Sacramento, USA) kindly proofread the paper and corrected the English language. The work reported here was partly funded by the ‘Fauna Ibérica’ Project PGC2018-095851-A-C65 of the Spanish Ministry of Science, Innovation and Universities. Antonio Ricarte’s position (Ref. UATALENTO17-08) at the University of Alicante is funded by the “Vicerrectorado de Investigación y Transferencia del Conocimiento”.