Ichneumonidae Latreille, 1802

Góis-Marques, Carlos A., Jesus, José, Sequeira, Miguel Menezes De & Madeira, José, 2019, The first Ichneumonid fossil from the Early Pleistocene of Madeira Island (Portugal), Zootaxa 4612 (3), pp. 447-450 : 448

Family Ichneumonidae Latreille, 1802

Genus and species indet.

Material: UMad-P500a (part: Fig. 2B ) and UMad-P500b (Counter-part: Fig. 2C ).

Description: Incomplete hind wing, composed of incarbonized venation, 10.6 mm (base of wing to the RSb apex) × 3.16 mm (2A apex to SC+R), venation more or less complete, except R1, and the missing vein C; bulla present in rs-m and CU-a. Vein 1-A partly detached from the sediment.

Remarks: Hind wing fossil architecture and size correspond to the Ichneumonidae ( Fig. 2A ). It is distinct from similar Braconidae hind wings, due to the enclosed VI cell ( Fig. 2A and D ) ( Broad, 2011), and vein rs-m apical to separation of veins RSa and RSb ( Goulet & Huber, 1993). Further identification is prevented, although the size and venation points to a large ichneumonid parasitoid wasp. Genera with similar hind wing size and venation occur today in Madeira, including Amblyteles , Ophion , Ichneumon , and Rhyssa ( Aguiar, 2008; Aguiar et al., 2017). However, to identify the specimen to genus and/or species, more complete fossil specimens are needed, as Ichneumonidae taxonomy is based on fore wing and body morphology (e.g. Goulet & Huber, 1993).

Today, Madeiran Ichneumonidae are represented by 98 spp., of which, 30 spp. are single island endemics ( Aguiar, 2008). Notwithstanding the high number of endemic species, literature reveals that Madeiran ichneumonids are understudied, being restricted mainly to check lists and taxonomy (e.g. Aguiar, 2008; Aguiar et al., 2017). Recent efforts include those of Santos et al. (2011), who demonstrated through host dissection and DNA barcoding that on Macaronesian Islands, parasitoids including Ichneumonidae , had a higher number of generalists (idiobionts) when compared to mainland. Studies dealing with immigration, evolution and divergence of ichneumonid parasitoid wasps in Madeira are currently lacking. However, the existence of a parasitoid wasp in Madeira Island at 1.3 Ma, certainly points to a complex trophic system already installed in the island.

We conclude that insect somatofossils on oceanic islands are rare, but when found, they can provide interesting palaeontological information. The specimen described is the first record for Madeira island and Macaronesia. It corresponds to a fossilized hind wing of an ichneumonoid parasitoid wasp from the Calabrian stage (1.3 Ma) in Madeira Island, implying also the existence of their hosts. Further entomological and palaeoentomological efforts are needed to understand the evolution of these wasps in an insular context.

Figures

FIGURE 2. Ichneumonidae hind wing morphology and comparison with the wing fossil. A, position and venation in Ichneumonidae (Ophion obscuratus Fabricius, 1798), figure adapted from Prehn & Raper (2016); B, Specimen UMad-P500a (part); C, Specimen UMad-P500b (counter-part); D, drawing interpretation of specimen UMad-P500a with venation nomenclature and cell numbers; arrows point to bulla.