Pelecocera

Lair, Xavier, Ropars, Lise, Skevington, Jeffrey H., Kelso, Scott, Geslin, Benoît, Minssieux, Elise & Nève, Gabriel, 2022, Revision of the genus Pelecocera Meigen, 1822 (Diptera: Syrphidae) from France taxonomy, ecology and distribution, Zootaxa 5141 (1), pp. 1-24 : 14-16

Key to the French species of Pelecocera

For several years we have used various keys to identify our specimens: Verlinden (1994), Stubbs & Falk (2002), Van Veen (2004), Haarto & Kerppola (2007), Speight & Sarthou (2017), but some features were not satisfactory: the colour of the legs is variable; the tergites may or may not have pairs of yellow or grey spots for the same species, especially on the autumn specimens ( P. pruinosomaculata , P. caledonica ), as already noted by Mik (1896) who recognised Pelecocera rectinervis Kertész, 1896 as a black morph of Pelecocera latifrons , now Pseudopelecocera latifrons ; and the presence or absence of a few white or black bristles on the anterior anepisternum is also variable for four of the six species.

For this work we examined about twenty-five characters and retained the most reliable ones. Characters examined, but not retained are: shape of the basoflagellomere, position of the arista on the basoflagellomere, shape of the face on lateral view, colour and pruisosity of the face, occiput width behind the inner corners of the eyes, colour of the setae on anterior anepimeron, pruinosity of the notopleuron, length of pili on the scutellum, leg colour, alula shape and distribution of microtrichia, pterostigma colour, pruinosity of the sternites, abdomen colour pattern, and genitalia shape.

For females, the most diagnostic feature is the shape of the vertex and frons, which is unique for each species ( Fig. 7 ). In P. lugubris and P. caledonica , the vertex appears as a continuation of the upper frons. In the other species, there is a discontinuation (ridge) between the lower and the upper frons, the latter being continuous with the vertex. The length from the anterior ocellus to the ridge of the vertex is also characteristic of each species. Pelecocera garrigae females have the peculiarity of not having any pollinose transverse band above the lunule ( Fig. 2C ), unlike all the other species.

1. Arista thick, inserted apically on basoflagellomere, composed of 3 highly visible segments in females, very short in males ( Fig. 8A ). Anepimeron, katepisternum and katepimeron partly shiny black....................................................................... P. tricincta (Abdomen with 3 yellow fasciae, sometimes narrowly interrupted in the middle)

- Arista hair-like, inserted dorsally on basoflagellomere ( Fig. 8B ). Anepimeron, katepisternum and katepimeron entirely grey pollinose................................. 2 (Abdomen with orange or greyish pairs of maculae, or completely black)

2. Basal radial (r) and basal medial (bm) wing cells partly bare......................................... P. caledonica (Lunule polished on lateral arms and median triangle. Female frons polished black and slightly swollen and regularly convex, flanked by two parallel lines along the eyes, which reach the transverse pollinose band above the lunule, without being reduced anteriorly as in P. lugubris )

- Basal radial (r) and basal medial (bm) wing cells entirely covered with microtrichia................................. 3

3. Anterior anepisternum with some white pile on the anterodorsal part (few and short in P. garrigae ). Middle paraface wider (or as wide) than the diameter of the anterior ocellus ( Figs. 9A and 9B )............................................. 4

- Anterior anepisternum without pile. Paraface narrower than the diameter of the posterior ocellus ( Fig. 9C and 9D )........ 5

4. Lunule entirely grey pollinose ( Fig 10A ). Paraface wider than diameter of anterior ocellus ( Fig. 9A )........... P. lugubris (Female: Frons strongly swollen after the vertex, forming a large, polished triangle bordered by two lines directed towards the lunule. Distance between the anterior ocellus and the apex of the triangle is approximately 4-5 times the diameter of the anterior ocellus. Punctation of the frons very thin and sparse. Transverse pollinose band above the lunule. Male: grey pollinose frons.)

- Lunule brownish or blackish, slightly polished, and not pollinose ( Fig 10B ). Paraface as wide as diameter of anterior ocellus ( Fig. 9B )............................................................................. P. garrigae sp. nov. (Female: Frons polished posteriorly to the vertex, delimited by a curved transverse line (ridge) between the two eyes: the distance between the anterior ocellus and the ridge is 2 to 3 times the diameter of the anterior ocellus. Anterior half of the frons strongly punctate, hardly polished, without transverse pollinose band above the lunule unlike all other Pelecocera species. Male: Frons punctate, slightly polished.)

5. Lunule with grey pollinose median triangle strongly contrasting with polished lateral arms ( Fig. 10C ). No setae on posterior anepisternum and notopleuron. Metafemora and metatibia completely yellow........................... P. scaevoides (Female: Distance between anterior ocellus and ridge very short, barely as long as diameter of the anterior ocellus. Ridge straight in the middle between the two eyes. In some specimens there is no visible ridge, the curvature of the frons is regular. Narrow transverse pollinose band above lunule.)

- Lunule completely grey pollinose ( Fig. 10D ). Setae present on posterior anepisternum and notopleuron. Metafemora and metatibia usually with black ring............................................................. P. pruinosomaculata (Female: Distance between anterior ocellus and ridge short, about 1.5 - 2 times longer than diameter of the ocellus. Male: Flagellum almost entirely black or only black on the distal half. Spring specimens have more contrasting black and yellow legs, and less variability on the abdomen, especially males with obvious yellow spots. In large populations of autumn, there is a high variability in the coloration of the legs and the abdominal pattern. We do not know any locality with both generations, spring and autumn).

Figures

FIGURE 2. Pelecocera garrigae sp. nov. paratype female: A: head and abdomen: lateral view, B head frontal view, C: head, dorso-lateral view, D and E: abdomen: dorsal views. Scale bars = 1 mm.

FIGURE 7. Photographs and schematic dorsal views of Pelecocera heads, showing the shape of the swollen part of the vertex in females of A: P. scaevoides, B: P. pruinosomaculata, C: P. lugubris, D: P. garrigae sp. nov. and E: P. caledonica.

FIGURE 8. Head, lateral view, A: Pelecocera tricincta, B: Pelecocera garrigae sp. nov..

FIGURE 9. Head, frontal view to show parafaces (arrow) of different Pelecocera species from France.A. Pelecocera lugubris, B: Pelecocera garrigae sp. nov., C: Pelecocera scaevoides, D: Pelecocera pruinosomaculata.

FIGURE 10. Head semi-lateral view to show the lunules (arrow) of: A. Pelecocera lugubris, B: Pelecocera garrigae sp. nov., C: Pelecocera scaevoides, D: Pelecocera pruinosomaculata.