Eristalis (Syrphidae, Diptera) in peninsular Spain

There is a key (K) to the Eristalis flies of the West Paleartic region which describes 20 species. Iberfauna (I) list 11 in Spain, and 9 of them have observations in iNat (N). There is also one observation of the American species E. stipator.
-E. alpinus (K) (I)
-E. arbustorum (K) (I) (N)
-E. cryptarum (K) (I)
-E. horticola (I) (N)
-E. intricaria (K) (I) (N)
-E. jugorum (K) (I) (N)
-E. nemorum (I) (N)
-E. pertinax (K) (I) (N)
-E. rupium (K) (I) (N)
-E. similis (K) (I) (N)
-E. tenax (K) (I) (N)

I will adapt the key to Spain:

1. Bumble bee like species; thorax with dense pile which obscures the base color: E. intricaria
   -Bee like species; thorax with pile which does not obscure base color: 2

2. Antenna orange yellow. All tibiae orange: E. cryptarum
   -Antenna brown to brownish black. At least tibia of fore and hind legs partly black: 3

3. Face with pale pollinose (worn specimens may have a narrow trace of a shiny medial stripe on lower half): E. arbustorum
   -Face with a shiny black medial stripe: 4

4. Medial stripe of face very wide, up to 1/3 of width of the face. Eye in the middle with a dorsoventral band of denser and generally darker pile. Katepimeron hairy: E. tenax
   -Medial stripe narrower than 1/3 of the face. Katepimeron bare: 5

5. Tarsi of fore and mid legs entirely yellow: E. pertinax
   -Tarsi of fore and mid legs party or entirely dark: 6

6. Arista long haired; the longest hairs about as long as 1/3 the length of the arista. Pterostigma very long, about six times as long as broad: E. similis
   -Arista hairs shorter than 1/3 the length of the arista, but several times as long as the arista at the base. Perostigma also shorter: 7

7. Hind femur somewhat swollen and arcuate, more so in the male. Anterior half of mesonotum dulled by greyish patterned pollinosity. Wings with a more or less obvious cloud across the middle: E. alpina
   -Hind femur slender and straight. Anterior half of mesonotum not dulled by greyish patterned pollinosity: 8

8. Face yellow with a distinct black median stripe sharply separated from the yellow base. Pterostigma longer than broad. Face deeply anteroventrally produced, in profile about as much as the width of an eye. Hind femur normally black at the base: E. jugorum
   -Face black or only obscurely yellow at the sides. Pterostigma long, 3-3.5 times longer than broad. Hind metatarsus orange-yellow. Female with tergites 2-4 brightly shining, without dull traverse bands. (also distinctive male genitalia visible in the key): E. rupium

Unfortunately, the guide considers E. jugorum, E. nemorum and E. horticola as synonyms, so I don't know about the accuracy of the last question. Seeing pictures of E. jugorum, it doesn't even sheem to have a yellow face. Some notes on those 3 species from observing the pictures in iNat: all three have abdomens with light transversal stripes, and two orange blotches at the sides of the first abdominal segment. in E. jugorum and E. horticola these blotches seem roundish, but in E. nemorum they are more fang-like. In males of E. arbustorum, these same blotches are also distinctive, giving the central black region an hourglass shape. E. horticola and E. jugorum have distintive black wing markings.
A couple observations with interesting commentary on E. horticola and E. jugorum:
https://www.inaturalist.org/observations/54184998
https://www.inaturalist.org/observations/19252915
https://www.inaturalist.org/observations/51623799

The abdomens of E. similis and E. pertinax have a tapered look, at least in some cases, but the tarsi have different colors (yellow/orange in pertinax, at least partially black in similis)

Link to the West Paleartic key: https://www.researchgate.net/publication/269928346_The_West_Palaearctic_species_of_the_genus_Eristalis_Latreille_Diptera_Syrphidae

Species listed in Spain: http://iberfauna.mncn.csic.es/showficha.aspx?rank=T&idtax=49175

Posted on March 15, 2024 07:43 PM by antonva