A new canthariphilous species of the genus Atrichopogon Kieffer, 1906 from central Italy (Diptera: Ceratopogonidae)

Abstract The new species Atrichopogon (Atrichopogon) tolfensis n. sp. from Tolfa Mountains (Italy, Latium, and Rome) is described and illustrated. Both sexes of the species were collected using cantharidin-baited traps from June 2020 to January 2021. The new species is an atypical member of the genus Atrichopogon.https://urn:lsid:zoobank.org:pub:3A012331-57D7-4532-B3F9-FDEE7C988FFD

The species described below belongs to the subgenus Atrichopogon s. str., which is the most difficult to identify and the most neglected group within the genus. Indeed, this subgenus includes very similar species whose characters for taxonomic identification are limited and highly variable.
The purpose of this paper is to describe a new European species in the subgenus Atrichopogon s. str. which was collected with cantharidin-baited traps in central Italy.

Material and methods
All examined specimens were collected from two sites in derived pastures within oak (Quercus Linnaeus) woodlands at the western base of Tolfa Mountains: site A (Italy, Latium, Rome, Tolfa, 42.058716N, 11.941148E; 48 m a.s.l.) (Figure 1(a,b)) and site B (Italy, Latium, Rome, Tolfa, 42.092617N, 11.974103E; 298 m a.s.l.) (Figure 1(c,d)). Two pairs of funnel traps were placed in each site. Paired traps consisted in one cantharidin-baited trap and one control trap, based on the protocol described in Horiuchi et al. (2018). Paired traps were about 2 m distanced, and the distance between pairs was about 30 m. Traps were active for 24 h every 2 weeks (approximately) for 1 year (June 2020-June 2021). After 24 h, traps were capped with cotton wool and stored at −20°C to euthanize the specimens. Specimens were then preserved in 70% ethanol.
Specimens were mounted on microscope slides in phenol-Canada balsam following the method described by Wirth and Marston (1968). The photograph of a female was taken with a LAS Montage multi-focus camera attached to a Leica stereo microscope M205A (Figure 2). The materials are housed in the collection of extant invertebrates of the Department of Invertebrate Zoology and Parasitology, University of Gdańsk, Poland (CEIG), and the Zoological Museum of Roma (Museo Civico di Zoologia), Italy (MCZ). We employ the traditional terminology of Ceratopogonidae as described in Szadziewski (1986).

Diagnosis
Small, dark brown biting midge with wing length 0.95-1.35 mm. Both sexes have pubescent eyes, terminal flagellomere blunt or with conical to cylindrical apical prolongation, single seta on paratergite, 0-3 setae on anterior anepisternum and four marginal bristles on scutellum; female (Figures 2 and 3) with single ovoid seminal capsule, wing membrane with macrotrichia in cells r 2+3 , m 1 and few in m 2 ; male with wing membrane bare and unique aedeagus bearing slender hourglass-like caudomedian projection with dark semi-elliptic base in ventral view (Figure 4).
Male (Figure 4) Similar to female, with usual sexual differences. Eyes pubescent. Flagellum with 13 separated flagellomeres, total length 0.65-0.75 mm, distal four flagellomeres elongate, plume well developed, terminal flagellomere with blunt apex or with conical to cylindrical apical

Etymology
The specific name refers to the Tolfa Mountains near Rome, the type locality of the new species.

Conclusive remarks
The new species has unique aedeagus with hourglass dorsal caudomedian expansion with semi-elliptic dark base (Figure 4). Such a character is unknown in all other species of the subgenus described from Europe, North Africa, the Middle East, the Caucasus, and Central Asia (Goetghebuer 1934;Clastrier 1956;Remm 1967Remm , 1980Szadziewski 1984Szadziewski , 1986Szadziewski , 2001Szadziewski et al. 1996;Alwin-Kownacka et al. 2016). Noteworthily, this new species represents an atypical member of the genus Atrichopogon as its terminal flagellomere 13 is blunt or without apical nipple-like prolongation, i.e. it has no constriction at base (Figure 3(b)). Indeed, to the best of our knowledge, all adults of European species within the tribe Forcipomyiini (including two genera: Forcipomyia Meigen, 1818, and Atrichopogon) have very characteristic nipple-like prolongation on apex of terminal flagellomere. Moreover, A. tolfensis n. sp. has the anterior anepisternum bearing 2 (0-3) short setae, which is totally bare in the European congeneric species.
A. tolfensis n. sp. is the eighth on the list of canthariphilous Ceratopogonidae in Europe. The presence of

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R. Szadziewski et al. males (15) and females (21) in cantharidin-baited traps evidences that both sexes are attracted to cantharidin with no significant difference: binomial test p-value >0.05 (= 0.256). Nevertheless, it should be emphasised that the attraction to cantharidin of biting midges does not demonstrate by itself interspecific interactions with cantharidin-producing species. Indeed, some species could just confuse cantharidin with similar plant or fungal molecules used in food search (Frenzel et al. 1992;Hashimoto & Hayashi 2014). Further investigations are needed to understand the canthariphilous behaviour of this species and the evolution of canthariphily in Ceratopogonidae.