Tenthredopsis ornata (Serville, 1823), (a sawfly)


24 May 2016 at OSGR: SU01 in South Wilts, England

Record SummaryFemale, visiting Cow Parsley
Found asFemale imago
Date24 May 2016
Associated organismAnthriscus sylvestris
OS grid refOSGR: SU01
Lat/Lon50° 60’ N, 1° 60’ W
Vice CountySouth Wilts, VC no: 8
CountryEngland
Voucher24 May 2016[K]
(Please quote this in any queries about this record)

Notes:

Length 9mm.

Clypeus deeply emarginate. Orange saddle on abdomen with row of dark marks running down the centre.

Keys to excisa in Benson, but this species has been split. Clypeus deeply incised and punctured; mesopleura shallowly and distantly punctured but shiny; abdomen black with middle segments red; 9mm, hind tarsi black (from above, brown from side), ant 8 ratio=4.6. Clypeus partly white. But sternites with 2 longitudinal black bands..

The dark object in the abdomen was 1mm long, curved-ellipsoid, smooth, black. At first it collapsed slightly as it started to dry, but once glued down it retained its shape. A piece flaked off when prodded with a pin: it’s apparently melanised chitin but with no sign of segmentation.

My best guess is that the sawfly larva was parasitised by something (Hyalurgus lucidus perhaps or a horsehair worm) which the host defences succeeded in killing, then it encapsulated the remains.

The following literature was used to identify this find:

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