A new parasitoid wasp (Hymenoptera: Chalcidoidea) from the Lower Cretaceous Crato Formation of Brazil: The first Mesozoic Pteromalidae Nathan Barling a , Sam W. Heads b , David M. Martill a, * a School of Earth and Environmental Sciences, University of Portsmouth, Burnaby Road, Portsmouth PO1 3QL, UK b Illinois Natural History Survey, University of Illinois at UrbanaeChampaign,1816 South Oak Street, Champaign, IL 61820, USA article info Article history: Received 12 February 2013 Accepted in revised form 14 May 2013 Available online xxx Keywords: Brazil Crato Formation Aptian Hymenoptera Chalcidoidea Pteromalidae abstract A new genus and species of small (3.5 mm excluding ovipositor) parisitoid wasp is described from the Lower Cretaceous (Aptian) Crato Formation Lagerstätte of Brazil. Parviformosus wohlrabeae gen. et sp. nov. is known from a single female imago and is assigned to Pteromalidae. It is diagnosed by the robustness of the scutellum, the structure, size and positioning of the mesopleuron, the complexity of the propodeumepetiole junction and a posteriorly curved dorsal ‘lip’ on metasomal segment 4. At only 3.5 mm in length, P. wohlrabeae is the smallest fossil wasp from the Cretaceous of South America and the first Mesozoic representative of Pteromalidae. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The Hymenoptera is one of the most diverse orders of insects. It is characterised by impoverished wing venation (most veins sim- ple, excluding rare SC branching and RS forking (forewing), pter- ostigmal cell lost or thick, M fused with Cu sub-basally), the presence of hamuli on the hind wings, haplodiploid sex determi- nation, and the presence of a protibial spur with velum (Rasnitsyn, 2002; Grimaldi and Engel, 2005). The hymenopteran fossil record is well-documented and data suggests that hymenopterans are a sister taxon to Panorpida and likely diverged during the Carbonif- erous (Beutel et al., 2011). Hymenoptera underwent a series of explosive adaptive radiations in the Jurassic, Cretaceous and Paleogene through which they attained their astonishing modern diversity (Riek, 1955; Rasnitsyn, 1969, 2002; Grimaldi and Engel, 2005; Michez et al., 2009). Their hyperdiversity is at least in part due to the evolution of microscopic parasitoid wasps, which constitute the vast majority of species in the order (Kristensen, 1981; Rasnitsyn, 2002; Grimaldi and Engel, 2005). Here, we describe a new genus and species of tiny parasitoid wasp from the Lower Cretaceous (Aptian) Crato Formation, a heterolithic sequence of interbedded laminated limestones, sandstones, marls and clays within the Araripe Basin of north-east Brazil (Heimhofer and Martill, 2007; Heimhofer et al., 2010). At its base is the Nova Olinda Member, a fossil KonservateLagerstätte of Aptian age that is well known for the abundance and exceptional preservation of ar- thropods, vertebrates and flora (Grimaldi,1990; Martill,1993; Martill et al., 2007). This member crops out around the north-eastern to south-eastern edges of the Chapada do Araripe, a typical Brazilian tableland in the north-eastern state of Ceará. The outcrop between Nova Olinda, Santana do Cariri and Tatajuba is especially fossiliferous, yielding large numbers of insects (Martill, 1993; Heads et al., 2008). 2. Material and methods Material. The specimen described here comprises a single adult female wasp preserved in right lateral aspect on a circular slab (diameter 32 mm, depth 10 mm) of fine-grained laminated lime- stone. It has been replaced by goethite, which may be a conse- quence of the weathering of an original iron sulphide replacing mineral (Menon and Martill, 2007). It is largely preserved in three- dimensions with only slight compactional damage, largely concentrated over the metathorax and propodeum. The specimen is deposited in the Staatliches Museum für Naturkunde, Stuttgart with accession number SMNS 70092. Methods. The partially exposed insect was etched in 10% hydrochloric acid to reveal more anatomical detail but was not removed from the * Corresponding author. E-mail addresses: nathan.barling@port.ac.uk (N. Barling), swheads@illinois.edu (S.W. Heads), david.martill@port.ac.uk (D.M. Martill). Contents lists available at SciVerse ScienceDirect Cretaceous Research journal homepage: www.elsevier.com/locate/CretRes 0195-6671/$ e see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.cretres.2013.05.001 Cretaceous Research xxx (2013) 1e7 Please cite this article in press as: Barling, N., et al., A new parasitoid wasp (Hymenoptera: Chalcidoidea) from the Lower Cretaceous Crato Formation of Brazil: The first Mesozoic Pteromalidae, Cretaceous Research (2013), http://dx.doi.org/10.1016/j.cretres.2013.05.001