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The first Ichneumonid fossil from the Early Pleistocene of Madeira Island (Portugal)
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Advisor(s)
Abstract(s)
In oceanic islands, well age-constrained deposits containing arthropod somatofossils (body fossils) are rare.
However, when available, these are important for providing empirical and independent minimum ages for molecular phy logenetic dating and complementary data on taxonomy, evolution and palaeobiogeography information of the biological
groups found as fossils. This is especially important for taxa that speciated within oceanic islands, many becoming single
island endemics (SIE). Recently, associated with a 1.3 Ma (Calabrian) fluvial and lacustrine sedimentary deposit from
Porto da Cruz in Madeira Island (Fig. 1), a wing, putatively identified as Hymenoptera, was found. Here we describe this
wing fossil as belonging to Ichneumonidae, a group with ca. 30% of SIE in Madeira Island. Moreover, this is the first
somatofossil of ichneumonid parasitic wasps found in Madeira Island and in Macaronesian islands (i.e. Azores, Madeira,
Canaries and Cabo Verde).
Since the 19th century, oceanic island attracted several naturalists due to the high probability of finding taxonomical
novelties (e.g. Vieira, 2005). Darwin (1859) amplified this interest, as oceanic islands biota presented a central role to
explain evolution. Today oceanic islands became the ideal locations to study evolution, biogeography and ecology (e.g.
Whittaker et al., 2017).
Madeira Island (Central Atlantic Ocean; Fig. 1), geologically a shield volcano of 7 Ma (Ramalho et al., 2015 and
references therein), is considered an insect diversity hotspot where 3019 species and subspecies are known, of which 665
are SIE (Borges et al., 2008). This diversity is most probably explained by stepping-stone through palaeo-Macaronesian
islands and isolation (Triantis et al., 2010; Fernández-Palacios et al., 2011).
Palaeoentomological records are rare in Madeira. The only known record is from the Mio-Pleistocene deposit of
São Jorge (see Góis-Marques et al., 2018), where Heer (1857) described an extinct coleopteran, Laparocerus wollastoni,
based on fossilized elytra. Machado (2006) in a taxonomic review of Laparocerus considers this taxon as nomen dubium,
due to the missing holotype and the impossibility of reapraising its taxonomy. On other Macaronesian archipelagos, espe cially in the Canaries Islands, several deposits with insect ichnofossils have been described (e.g. Edwards & Meco, 2000;
Meco et al., 2011; La Roche et al., 2014). In Azores only xylophagous ichnoentomological traces in charcoal wood are
known (Góis-Marques et al., 2019b).
The fossil wing was found within laminated lacustrine fine sandstone, associated with plant fossils. The sediments
are constrained by two 40Ar-39Ar dates to 1.3 Ma, Calabrian stage (Góis-Marques et al., 2019a). Fossils are kept in the
palaeobotanical collection at the Madeira University herbarium (UMad-P) with the numbers UMad-P500a (part) and
UMad-P500b (counter-part). The wing fossil was studied under a stereo microscope, and its identification was performed
through several sources (e.g. Goulet & Huber, 1993) and specific guidebooks (Prehn & Raper, 2016). Wing description
follows the Comstock-Needham system as described by Quicke (2015)
Description
Keywords
Ichneumonid fossil Pleistocene Madeira Island (Portugal) . Faculdade de Ciências da Vida
Citation
Gois-Marques, C. A., Jesus, J., De Sequeira, M. M., & Madeira, J. (2019). The first Ichneumonid fossil from the Early Pleistocene of Madeira Island (Portugal). Zootaxa, 4612(3), 447-450. https://doi.org/10.11646/zootaxa.4612.3.13
Publisher
Magnolia Press