Short communicationA new genus and species of parasitic wasps (Hymenoptera: Diapriidae) from Hkamti mid–Cretaceous Burmese amber
Introduction
Diapriidae remain poorly documented in Cretaceous ambers, which is very surprising considering the number of pieces of amber containing representatives of this family (C.J pers. obs). Perrichot & Nel (2008) proposed a summary of the fossil record of the family and reported ca. fifty inclusions, mainly Cenozoic and distributed among the subfamilies Diapriinae Haliday, 1833 and Belytinae Förster, 1856. After this paper, the fossil record of the family has increased, with the papers of Lak and Nel, 2009, Engel et al., 2013 and Rasnitsyn and Öhm-Kühnle (2019) for the Cretaceous, and Antropov et al., 2014, Archibald et al., 2018, and Van de and Kamp et al. (2018) for the Cenozoic. Nevertheless, it remains largely underestimated for major deposits such as the Burmese and Baltic ambers.
Diapriid wasps are small endoparasitoids of flies, ants, and beetles (Loiacono, 1987, Masner, 1993). Their modern diversity is greatly underestimated according to Johnson (1992), with ‘only’ 2088 described extant species (Johnson et al., 2019: https://hol.osu.edu). This would represent half of the estimated extant diversity of this family. This family shows a wide distribution in most of the ecozones. As mentioned in Königsmann, 1978, Rasnitsyn, 1988, Dowton et al., 1997, Dowton and Austin, 2001, Rasnitsyn, 2002, and Castro & Dowton (2006), the superfamily Proctotrupoidea appears to be composed by paraphyletic groups. Sharkey (2007) separated the Diaprioidea from this superfamily. According to recent phylogenetic studies, the Diaprioidea seems to be the sister lineage of the Proctotrupoidea or of the Chalcidoidea, and possibly diverged at the beginning of the Jurassic (Dowton et al., 1997, Castro and Dowton, 2006, Peters et al., 2017). The concept of Diaprioidea also varied through time: Rasnitsyn (1980)'s concept of Diaprioidea comprised Platygastroidea, Mymaridae Haliday, 1833, Austroniidae Kozlov (in Rasnitsyn, 1975), Diapriidae Haliday, 1833, Monomachidae Ashmead, 1902 and the extinct Serphitidae Brues, 1937; while Sharkey et al. (2012)'s concept included Maamingidae Masner, Naumann & Austin, 2001, Diapriidae (with the Ismaridae as a subfamily), and Monomachidae. Engel et al. (2013) added the Mesozoic family Spathiopterygidae Engel & Ortega-Blanco, 2013 to the Diaprioidea.
Two putative synapomorphies allow a quick recognition of the Cynipoidea and Diaprioidea: the concave/convex vein M(+Cu) on the hind wing and the male basal flagellomere modified to accommodate the gland secretion releaser (Rasnitsyn, 1988, Rasnitsyn, 2002). Sharkey et al. (2012: 99) proposed two different synapomorphies to support the clade Diaprioidea except Ismarus: subantennal shelf present, and ventral transverse carina of metapleuron absent or weakly developed, but these authors added that they are ‘convergent in some members of most Proctotrupomorpha superfamilies’. Unlike the cosmopolitan and speciose Diapriidae, the Monomachidae and the †Spathiopterygidae are represented by a small number of species (less than 10 species for the later), and can be differentiated from the others families composing the Diaprioidea by a typical wing venation (Engel et al., 2013, Engel et al., 2015, Krogmann et al., 2016). The Ismarinae can be easily differentiated from the other Diapriidae by the lack of facial projection from which the antennae arise, and characterized by various degrees of fusion of the metasomal terga. The family Monomachidae is represented by the three genera Monomachus Klug, 1841 (with Tetraconus Szépligeti, 1903 as junior synonym), and Chasca Johnson & Musetti, 2012 (Naumann and Masner, 1985, Musetti and Johnson, 2000, Johnson and Musetti, 2012), only found in the Neotropical and Australian regions. Females are readily recognized by ‘their elongate, loosely articulated, weakly sclerotized, and acuminate metasoma’, as a putative synapomorphy (Johnson & Musetti, 2012: 1). The Diapriidae can be differentiated by the medium to small sizes, the antennae elbowed, the scape inserted high above clypeus, usually on a prominent transverse ledge; fore wing without stigma but sometimes with slightly thickened marginal vein; metasoma distinctly petiolate with true or apparent tergum 2 the longest; ovipositor almost entirely retracted (Goulet & Huber, 1993). Four subfamilies are currently recognized within diapriids: Ambositrinae, Belytinae, Diapriinae, and Ismarinae. The Belytinae and Diapriinae seem to be the most diverse ones compared to the other subfamilies. The monophyly of Diapriidae except Ismarus is supported by six morphological character states not present in Ismarus, i.e., third maxillary palpomere enlarged, broader than the following palpomere, and triangular; pronotal transverse carina absent; lateroventral corners of pronotum with medial inflexions abutting mesopleuron; prophragma of mesonotum not subdivided by slit; a distinct longitudinal ridge of metapleuron ventral to propodeal spiracle present; metaphragma and metapleural apodeme fused (after Sharkey et al., 2012).
Herein we described and figure a new genus and species of Belytinae based on new material from Burmese amber.
Section snippets
Material and methods
The amber piece containing the specimen studied herein derive from the deposits of Hkamti site, Hkamti District, Sagaing Region, Myanmar. The Hkamti site is about 80 km southwest of the Angbamo site. Radiometric data established an early Cenomanian age (98.79 ± 0.62 Ma) for Kachin amber, based on zircons from volcanic clasts found within the amber-bearing sediments (Shi et al., 2012). Some ammonites found in the amber-bearing deposits corroborates a late Albian–early Cenomanian age (Cruickshank
Systematic palaeontology
Order: Hymenoptera Linnaeus, 1758.
Superfamily: Diaprioidea Haliday, 1833.
Family: Diapriidae Haliday, 1833.
Subfamily: ?Belytinae Förster, 1856.
Genus: Protobelyta gen. nov. Jouault & Nel
urn:lsid:zoobank.org:act:483AF931-4783-449D-9E79-9ACE673D95E2.
Type species. Protobelyta monsirei sp. nov.
Etymology. The genus name is a combination of the Greek « prôtos » meaning ‘primitive’ and Belyta, type genus of the Belytinae. Gender feminine.
Diagnosis. ead short; eyes glabrous; antenna 15-segmented,
Discussion
Following the key of the extant Proctotrupoidea from Goulet & Huber (1993) the specimen keys out in Diapriidae because it possesses an elongated scape (more than 2.5 longer than wide); head in lateral view with antennal shelf distinct; fore wing pterostigma linear. These characters are also proposed by Sharkey (2007) to define the Diaprioidea and fit with the specimen. Protobelyta monsirei gen. et sp. nov. differs from the Spathiopterygidae in the complete wing venation and the 15 antennomeres,
Conclusion
Even if the modern Belytinae are found worldwide and arbor a wide diversity in moist temperate forests of the southern hemisphere (Masner, 1993), the fossil record of the Diapriidae in paratropical habitat like that of the Cretaceous Burmese amber is poor. However, the subfamily was already widely distributed during the Albian–Cenomanian since it is now recorded in the French, Spanish, and now Burmese amber deposits. This new description confirms that the Proctotrupoidea are already
CRediT authorship contribution statement
Corentin Jouault: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Writing - original draft, Writing - review & editing. Vincent Perrichot: Data curation, Investigation, Methodology, Writing - original draft. André Nel: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Supervision, Writing - original draft, Writing - review & editing.
Acknowledgements
We express our gratitude to the Editorial Board of Cretaceous Research, and in particular Dr. Eduardo Koutsoukos. We thank Pr. A. Rasnitsyn and an anonymous reviewers for their valuable comments on this manuscript.
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