Cicadellidae: Cicadellinae: Cicadellini

Draeculacephala robinsoni Hamilton

Draeculacephala robinsoni Hamilton, 1967: 767

Draeculacephala sphagneticola Hamilton, 1985: 100

Material examined. We collected 116 specimens (54 ♀, 53 ♂, 9 nymphs) in the 11 sites where the species was found to occur and on the sticky traps for flying pest monitoring (Table 1). Adult specimens were measured and the colouration of the abdominal sterna was noted. Two specimens from Banyuls-sur-Mer (1 ♂, 1 ♀, on 23.v.2021) are deposited in the Hemiptera collection in the Muséum National d’Histoire Naturelle, Paris (MNHN) with accession numbers MNHN-EH 24788 and MNHN-EH 24789. In addition, two specimens (1 ♂, 1 ♀, caught on 22.vii.2021) from the same location are deposited at the US National Museum of Natural History, Washington, DC (USNM) with accession numbers 01513790 and 01513791. In October, when more sites had been discovered in France, specimens from Banyuls-sur-Mer (3 ♂, 2 ♀, caught on 07.x.2021) and Argelès-sur-Mer (3 ♂, 2 ♀, caught on 15.x.2021) were sent to INRA in Montpellier for genetic analyses. The remaining specimens from France are deposited in the personal collection of VR, the Spanish specimens are in the collection of AMN.

For comparison, numerous males and females of D. robinsoni from North America deposited at USNM, many of which were determined by C. Dietrich during the latest revision of the genus (Dietrich, 1994), were examined.

Identification. The preponderance of characters observed in the specimens found in France and Spain are most consistent with D. robinsoni sensu Dietrich (1994). These characters are documented from the Europeancollected specimens here, which may be helpful if future taxonomic or nomenclatural changes are made in this group. Following the key given in Dietrich (1994), the characters supporting the identification as D. robinsoni here are: 1) transpleural macula present (Fig. 4C, D +F), 2) hind femoral macrosetal formula 2+1+1, 3) hind tarsomere I outer row usually with one or two small paleate setae at base (Fig. 4J +K), 4) antennal ledge not uniformly dark brown (Fig. 4E +F), 5) forewing veins light blue (Fig. 3A +B, Fig. 4 A-D), 6) aedeagus dorsomedial process sharply pointed (Fig. 4G), 7) dorsal maculae of head distinct (Fig. 4A +B), 8) females>8.0 mm (46 ♀ measured: mean: 9.2 mm, min: 8.2 mm, max: 10.1 mm), male> 6.6 mm (50 ♂: mean: 7.4 mm, min: 6.8 mm, max: 8.0 mm), 9) clypellus in lateral view angulate (Fig. 4C +D), 10) mesonotum without submedial spots (Fig. 4A +B), 11) pronotum in lateral view with one postocular macula (Fig. 4C +D), 12) subgenital plates strongly tapered, macrosetae large, 13) male crown shorter than pronotum (Fig. 4B +D), 14) anteroventral angle of aedeagus lying cephalad of dorsal process (Fig. 4G) (caudad of process in D. producta according to Hamilton (1985), Fig. 51), 15) abdominal 2S apodeme (Fig. 4I) as in Hamilton (1985), Fig. 56A and 16) abdominal 3S apodeme closest to Fig. 61B of Hamilton (1985). As noted by Dietrich (1994) and as illustrated by Hamilton (1985), the apodemes of male sternites 2S and 3S appear to be quite variable within D. robinsoni and among species. Thus, their utility in diagnosing species may be limited in this group.

In Dietrich’s (1994) key, couplet 24, D. producta and D. robinsoni are separated in part by the coloration of the male abdominal sterna. D. producta is stated to have the sterna dark brown to black and D. robinsoni with the sterna entirely brown or with various amounts of yellow (or completely yellow in some Florida populations). Black abdominal sterna would, in part, suggest an identification of D. producta. However, most of the male specimens found in France and Spain have completely black abdominal sterna while in some the abdominal sterna are pale yellow which suggests variation within the species. Additionally, some specimens at USNM identified as D. robinsoni that are outside of the distribution of D. producta (e.g. from Edgewood, MD and Washington, DC) were observed with very dark brown to black abdominal sterna, again suggesting that this character is more variable than suggested in the key of Dietrich (1994).

In summary, the characters observed in the specimens from France and Spain strongly support the identification of D. robinsoni sensu Dietrich (1994) as currently understood. However, this taxonomically challenging species group deserves more attention in order to clarify species boundaries and characters that define them.

Distribution and biology in Europe. We were able to record D. robinsoni in 11 different sites that spanned a distance of 86 km from Argelès-sur-Mer in France to Estany de Sils in Spain (Fig. 1, Table 1). In France, it was found in the beds of the rivers Ballaury, Rec de la Coma Pascola, Massane, El Duí and El Ravaner. They were mostly dry but covered by lush green ruderal vegetation even during the hottest periods of the Mediterranean summer. In Spain the species occurred in large permanent wetland sites (Aiguamolls de l’Empordà, Estany de Sils, Estany de Banyoles) (Fig. 2C +D). In the Aiguamolls de l’Empordà the habitat consists of pastures and meadows which are the result of the drying out of large coastal lagoons located between the mouths of the rivers Muga and Fluvià. These grasslands are periodically flooded, naturally during the rainy season and artificially during the summer. Here, D. robinsoni has formed the densest populations and hundreds of specimens could be observed when walking through the wetlands. Population sizes in e.g. Rec de la Coma Pascola and El Duí in France were much lower and only few specimens could be recorded.

In both France and Spain adult specimens and nymphs were present all through the summer from the end of May when the species was first found until the end of October.

Potential host plants in France present in the riverbed of the Ballaury where the species was captured first were Agrostis stolonifera L., Arundo donax L., Avena sterilis L., Cynodon dactylon * (L.) Pers., Bromus catharticus* Vahl, Paspalum distichum * L., Polypogon viridis (Gouan) Breistr. and Polypogon maritimus Willd. (Poaceae) and Cyperus esculentus L., Cyperus eragrostis* Lam. and Scirpoides holoschoenus (L.) Soják (Cyperaceae). Non-native species are marked with an asterisk (*). In France, Paspalum disticum was found to occur in all sites where nymphs could be recorded. Larval development is thus likely to occur on this species of Poaceae.