New garden species

Apaeleticus inimicus ♀︎♂︎

Last update: 5 February 2021
OBSERVATION:
2019-VII-13

A very special new garden species this time!!
At the end of the day I saw two small wasps struggle in the waterfilled wheelbarrow. It was clear that they were ichneumonid wasps but which ones.

I couldn’t figure this one out so I called in the help of the Waarneming.nl forum where admin Fons Verheyde identified them as a pair of the ichneumonid wasp Baranisobas ridibundus, a rare species in the Netherlands.
See for the female here and for the manle here.

What makes this find even better is that according to him it is this could well be the first time the male has been photographed in the Netherlands and Belgium!!

Here they can both be seen grooming the water of their bodies. The female has a deformed right wing with a fold to the left in it. Unfortunately her photographs are rather bad. 

Apaeleticus inimicus ♂︎ sp. inc.
Apaeleticus inimicus ♀︎

Update 08/2020:
Baranisobas ridibundusApaeleticus inimicus

I’ve received an update from Fons Verheyde on the observation in Waarneming.nl informing me that it concerns a different species from the one established earlier (see above), a female and, possibly, a male, Apaeleticus inimicus.

The genus Apaeleticus has four representatives in the Netherlands [1]:

Species
Rarity [2]
A. bellicosus   uncommon  
A. haematodus   common  
A. inimicus    common  
A. mesostictus   uncommon  

It is a good practice to look for reference material to train the brain after receiving a positive ID on a species. But as is more often the case when dealing with an ichneumonid wasp the amount of available information can be minimal. I did manage to delve up some publications with good photographic material on some of the species:

SpeciesPublication
A. bellicosus[PUB-1]: New records of Cryptinae and Ichneumoninae (Hymenoptera: Ichneumonidae) species from Kerman province, Southeast Iran
[PUB-2]: Muséum National D’Histoire Naturelle
[PUB-3]: A survey on the tribes Phaeogenini and Platylabini (Ichneumonidae: Ichneumoninae) with two generic records for the fauna of Iran
A.haematodusno data available
no data available
A. inimicus[PUB-4]: Muséum National D’Histoire Naturelle
[PUB-5]: Two newly recorded species of the tribe Platylabini (Hymenoptera: Ichneumonidae, Ichneumoninae) from Iran
[PUB-3]: A survey on the tribes Phaeogenini and Platylabini (Ichneumonidae: Ichneumoninae) with two generic records for the fauna of Iran
no data available
A. mesostictus[PUB-6]: Muséum National D’Histoire Naturelle
no data available
Female
Apaeleticus inimicus ♀︎

The Ichneumoninae key [Tereshkin] [4] leads to the tribe Platylabini via these characters:

  • small wasp
  • scutellum elevated above postscutellum
  • ovipositor not visible

The Platylabini key [4] leads to Apaeleticus via these characters:

  • base areolet front wing wide
  • abdomen truncate, tergites 6 and 7 not visible
  • antennal flag shorter than front wing
  • front wing distinctly shorter than body length

A number of characters are not visible in my photographs but by making assumptions to see how the key resolves and by removal of genera that do not occur in the Netherlands a result can be found.

Based on the photo references my female seems to visually fit A. inimicus, and does not resemble the photographic sample of A. mesostictus [PUB-6] and A. bellicosus [PUB-1]. Unfortunately no information could be found on A. haematodus.
The morphologic characters in the species description in [PUB-3] en [PUB-5] cannot be checked for some parts due to the poor quality of my photographs that lack the necessary details, but the following characters match:

  • Antennal flag with 30 segments, white segments 6-10 [PUB-5]
    (note: [PUB-3] mentions 35 segments with 6 white segments. In my photo there are 30 segments and 4 white segments, matching [PUB-5])
  • First antennal segment flag 2.3x longer than wide apically [PUB-5]
  • Transverse furrow pronotum shallow [PUB-5]
  • Mesonotum moderately convex, width = 0.73x length [PUB-5]
  • Propodeal spiracle small and oval, 2x longer than wide [PUB-5]
  • Front wing with pentagonal areolet, smaller in front [PUB-5]
  • Tergite 1 punctated [PUB-5]
    (note: in my photo it seems like there is a flat or depressed middle area on tergite 1, but is not sharp so it could be a photographic artefact. I have not been able to find a genus or species that has such a character.)
  • Tergite 6 and 7 hidden under tergite 5 [PUB-3, PUB-5]
  • Tergite 5 truncated [PUB-3]
  • Ovipositor short [PUB-5]
  • Colour reddish with ivory white pattern on posterior margin pronotum, subalarum [PUB-5]
  • Vertex black with red [PUB-3]
  • Tegula and all legs red [PUB-5]
  • Postscutellum black [PUB-5]
  • Tergites 5 and 6 black [PUB-5]
  1. Flagellum with 30 segments, white segments 6-10
Apaeleticus inimicus ♀︎, flagellum with 30 segments, segments 6-10 white

2. First flagellum segment 2.3x longer than wide apically

Apaeleticus inimicus ♀︎, flagellum segment 1 length (L) = 2.3x width apically (W)

3. Pronotal transverse furrow shallow

Apaeleticus inimicus ♀︎, pronotal transverse furrow shallow

4. Mesonotum moderately convex, width (W) = 0.73x length (L)

Apaeleticus inimicus ♀︎, Mesonotum moderately convex, width (W) = 0.73x length (L)

5. Front wing with pentagonal areolet, wide base, narrower in front

Apaeleticus inimicus ♀︎, base pentagonal areolet wide

6. Tergites 6 and 7 hidden under tergite 5
7. Tergite 5 truncate
8. Ovipositor short
9. Tergites 5 and 6 black

Apaeleticus inimicus ♀︎, tergites 6 and 7 hidden under 5, tergites 5 and 6 black

10. Reddish color with ivory white pattern on posterior edge pronotum (P), subalarum (S) and scutellum
(Note: scutellum is ivory white in my female and all references, but is not specifically mentioned as character)

Apaeleticus inimicus ♀︎, roodachtig met ivoor wit patroon op achterrand pronotum (P), subalarum (S) en scutellum (Sc)

11. Postscutellum black

Apaeleticus inimicus ♀︎, postscutellum black

12. Tegula and all legs red

Apaeleticus inimicus ♀︎, tegula and all legs red

13. Vertex black and red

Apaeleticus inimicus ♀︎, vertex red with black

One thing that kind of bugged me has been resolved with the new species: the fact that the ovipositor was not visible on any of the photographs where it could have been. This fact kept some doubt in my mind concerning the positive id on B. ridibundus, as examples on the web showed a clearly visible, rather sturdy ovipositor.
This can now be explained because in Apaeleticus females the apical tergites are almost always hidden within tergite 5 and are therefore not visible [4, PUB-3, PUB-5], and the ovipositor does not protrude [4].

Male
Apaeleticus inimicus ♂︎ sp. inc.
Apaeleticus inimicus ♂︎ sp. inc.
Apaeleticus inimicus ♂︎ sp. inc.
Apaeleticus inimicus ♂︎ sp. inc.

The Ichneumoninae key [Tereshkin] [4] leads to tribe Platylabini via these characters:

  • small wasp
  • propodeal spiracle small and roundish
  • scutellum elevated above postscutellum

1. Propodeal spiracle small and roundish

Apaeleticus inimicus ♂, propodeal spiracle small and roundish

2. Scutellum elevated higher than postscutellum

Apaeleticus inimicus ♂, scutellum elevated above postscutellum

The Platylabini key [4] leads to genus Apaeleticus via these characters:

  • petiolus not flattened at base
  • base areolet front wing wide
  • propodeum with teeth
  • coxal carina developed
  • propodeal spiracle small and roundish
  • middle of face sharply protruding
  • trnsversal furrow pronotum interrupted by longitudinal keel
  • flagellum segments without tyloids
  • flagellum shorter than front wing
  • front wing distinctly shorter than body length

1. Petiolus base not flattened

Apaeleticus inimicus ♂, base petiolus not flattened

2. Areolet pentagonal, base wide

Apaeleticus inimicus ♂, areolet pentagonal, base wide

3. Propodeum with teeth

Apaeleticus inimicus ♂, propodeum with teeth

4. coxal carina developed

Apaeleticus inimicus ♂, coxal carina developmed

5. Propodeal spiracle small and roundish

Apaeleticus inimicus ♂, propodeal spiracle small and roundish

6. Middle of face sharply protruding

Apaeleticus inimicus ♂, middle face sharply protruding

7. Pronotal transverse furrow interrupted by keel

Apaeleticus inimicus ♂, transverse furrow interrupted by keel

8. Flagellum segments without tyloids

Apaeleticus inimicus ♂︎, antennae without tyloids
Apaeleticus inimicus ♂︎, antennae without tyloids

9. Flagellum shorter than front wing
10. Front wing distinctly shorter than body length

Apaeleticus inimicus ♂︎, flagellum shorter than front wing, front wing much shorter than body length

I could not find any reference photographs on the male A. inimicus. The photographs of the male A. bellicosus look rather similar to my male. According to the [Perkins] [3] key the difference between the two species are:

A. inimicus with shorter, clearly thickened flagellum
A. inimicus postpetiole apically smooth, irregularly longitudinally striate between spiracles

A. bellicosus with longer flagellum
A. bellicosus postpetiolus evenly, coarsely punctate

The postpetiole in my male does not match the description of A. bellicosus, and looking at the punctation in the photographs in [PUB-2] en [PUB-3] it is clearly different than the smooth surface in my male.

Apaeleticus inimicus ♂︎, postpetiole apical smooth, irregular longitudinally striate between spiracles

So in conclusion it is too bad the species is the uncommon A. inimicus instead of the rare B. ridibundus. Probably the scoop for photographing the male for the first time in the Netherlands and Belgium does not count here, but since there is no photographic material available yet it still feels a little like it, and they still remain beautiful little wasps. ✌️😊


References

1 Nederlands Soortenregister

2 Waarneming.nl

3 PERKINS, James F. Hymenoptera: Ichneumonoidea, Ichneumonidae, key to subfamilies and Ichneumoninae.

4 TERESHKIN, A. M. Illustrated key to the tribes of subfamilia Ichneumoninae and genera of the tribe Platylabini of world fauna (Hymenoptera, Ichneumonidae). Linzer Biologische Beiträge, 2009, 41.2: 1317-1608., pag: 1428, 1430

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