# New Burmese amber fossils clarify the evolution of bethylid wasps (Hymenoptera: Chrysidoidea)

Corentin Jouault, Valerie Ngô-Muller, Jean-Marc Pouillon, André Nel

► To cite this version:

Corentin Jouault, Valerie Ngô-Muller, Jean-Marc Pouillon, André Nel. New Burmese amber fos-
sils clarify the evolution of bethylid wasps (Hymenoptera: Chrysidoidea). Zoological Journal of the
Linnean Society, 2021, 191 (4), pp.zlaa078. 10.1093/zoolinnean/zlaa078. insu-02921314

HAL Id: insu-02921314

https://insu.hal.science/insu-02921314v1

Submitted on 6 Mar 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
# New Burmese amber fossils clarify the evolution of bethylid wasps (Hymenoptera: Chrysidoidea)

CORENTIN JOUAULT<fnref n="1" />,*, VALÉRIE NGÔ-MULLER<fnref n="2" />,<fnref n="3" />, JEAN-MARC POUILLON<fnref n="4" /> and ANDRÉ NEL<fnref n="2" />*

Received 7 February 2020; revised 11 June 2020; accepted for publication 12 June 2020

Two new bethylid wasps from Cenomanian Burmese amber, one tentatively placed in †Protopristocerinae: *Cretapristocera longiscapa gen. & sp. nov.* and one in †Holopsenellinae: *Megalopsenella pouilloni gen. & sp. nov.*, are described and illustrated here. They provide new data on the Cretaceous diversity of the family and extend the Cenomanian Burmese amber records to six species. We discuss their systematic placements and provide identification keys to species of †Holopsenellinae and †Protopristocerinae to assist future taxonomic studies. We phylogenetically analyse Bethylidae, adding several fossil taxa to a recent study, suggesting a new hypothesis for the relationships between the different subfamilies. We also address the distribution and underestimated diversity of the family during the Cretaceous and the evolution of the venation of their wings. Finally, we discuss the possible misplacement of the families Plumariidae and †Falsiformicidae.

ADDITIONAL KEYWORDS: Bethylidae — Cenomanian — fossil record — phylogeny — wing evolution.

## INTRODUCTION

The superfamily Chrysidoidea comprises 5632 extant species (HOL, 2020; https://hol.osu.edu). According to modern phylogeny, the superfamily occupies a ‘plesiotypic’ place in the evolution of Aculeata and seems to have appeared and diversified during the Jurassic, c. 224–160 Mya (Brothers, 1999; Mao et al., 2015; Peters et al., 2017; Tang et al., 2019). Among Chrysidoidea, the family Bethylidae appears to be the sister-group of Chrysididae, a placement supported by molecular and morphological data (Brothers & Carpenter, 1993; Carr et al., 2010).

Extant bethylid wasps are well diversified with 2920 valid species, distributed in 96 genera. They have a cosmopolitan distribution, but show a greater

diversity in the tropics (Azevedo et al., 2018). Modern species use a sting to paralyse their prey, and host taxa consist of larvae of Coleoptera, Lepidoptera and, rarely, Hymenoptera (Gauld & Bolton, 1988; Gordh & Móczár, 1990; Melo & Evans, 1993; Azevedo et al., 2018).

Bethylidae comprise eight subfamilies, of which three are extinct. They are frequent in amber, with more than 60 species described from the Cretaceous to the Holocene (Azevedo et al., 2018), and most taxa belong to the subfamilies Bethylinae and Epyrinae. The known Cretaceous records of the family comprise 18 species described from Burmese, Canadian, French, Lebanese, Russian and Spanish amber deposits (Cockerell, 1917a, b, 1920; Evans, 1973; Rasnitsyn, 1990; Azevedo & Azar, 2012; Ortega-Blanco & Engel, 2013; McKellar & Engel, 2014; Cockx et al., 2016; Engel, 2019; Colombo et al., 2020), but only six of these were from Burmese amber (see Table 1) belonging to Epyrinae, Holopsenellinae, Pristocerinae, †Protopristocerinae and Scleroderminae (Azevedo et al., 2018; Engel, 2019). It seems that Bethylidae have so far been little-described from Burmese amber. Here we present two new specimens of bethylid

<footnote n="1">¹Université de Rennes, CNRS, Géosciences Rennes, UMR 6118, F-35000 Rennes, France</footnote>

<footnote n="2">²UFR Sciences du Vivant, Université Paris Diderot, Université de Paris, F-75013 Paris, France</footnote>

<footnote n="3">³Institut de Systématique, Évolution, Biodiversité, ISYEB - UMR 7205 - CNRS, MNHN, UPMC, EPHE, Muséum national d'Histoire naturelle, Sorbonne Universités, F-75005 Paris, France</footnote>

<footnote n="4">⁴Nivolas Vermelle, France</footnote>

<footnote>*Corresponding author. E-mail: jouaultc0@gmail.com; anel@mnhn.fr.</footnote>

<footnote>[Version of record, published online 23 July 2020; http://zoobank.org/ urn:lsid:zoobank.org:pub:611CD23B-912B-4737-AE4C-82218A2B0216]</footnote>
<table><caption>**Table 1** Diversity and distribution of the Cretaceous Bethylidae</caption><thead><tr><th>Species</th><th>Distribution</th><th>Age</th><th>Reference</th></tr></thead><tbody><tr><td>Archaepyris minutus Evans, 1973</td><td>Taimyr, Russia</td><td>Late/Upper Santonian</td><td>Evans, 1973</td></tr><tr><td>Bethylitella cylindrella</td><td>Burmese amber</td><td>Early/Lower Cenomanian</td><td>Cockerell, 1917a</td></tr><tr><td>Celonophamia granama McKellar & Engel, 2014</td><td>Grassy Lake, Medicine Hat, Canada</td><td>Late/Lower Campanian</td><td>McKellar & Engel, 2014</td></tr><tr><td>Celonophamia taimyria Evans, 1973</td><td>Taimyr, Russia</td><td>Late/Upper Santonian</td><td>Evans, 1973</td></tr><tr><td>Cretabythus sibiricus</td><td>Taimyr, Russia</td><td>Late/Upper Santonian</td><td>Evans, 1973</td></tr><tr><td>Cretapristocera longiscapa</td><td>Burmese amber</td><td>Early/Lower Cenomanian</td><td>This study</td></tr><tr><td>Cretepyris martini Ortega-Blanco & Engel, 2013</td><td>Peñacerrada outcrop I, Spain</td><td>Late/Upper Albian,</td><td>Ortega-Blanco & Engel, 2013</td></tr><tr><td>Cretobethylellus lucidus Rasnitsyn, 1990</td><td>Pavlovka Settlement, Russia</td><td>Aptian</td><td>Rasnitsyn, 1990</td></tr><tr><td>Epyris atavellus Cockerell, 1920</td><td>Burmese amber, Myanmar</td><td>Early/Lower Cenomanian</td><td>Cockerell, 1920</td></tr><tr><td>Foenobethylus electriphila (Cockerell, 1917)</td><td>Burmese amber, Myanmar</td><td>Early/Lower Cenomanian</td><td>Cockerell, 1917b; Colombo et al., 2020</td></tr><tr><td>Holopsenella primotica Engel, Ortega-Blanco & Azevedo, 2016</td><td>Bchare Mountain, Lebanon</td><td>Barremian</td><td>Engel et al., 2016</td></tr><tr><td>Holopenselliscus pankowskiorum Engel, 2019</td><td>Burmese amber, Myanmar</td><td>Early/Lower Cenomanian</td><td>Engel, 2019</td></tr><tr><td>Lancepyris opertus Azevedo & Azar, 2012</td><td>Ain Dara, Caza Aley, Lebanon</td><td>Early/Lower Barremian</td><td>Azevedo & Azar, 2012</td></tr><tr><td>Liztor pilosus Ortega-Blanco & Engel, 2013</td><td>Peñacerrada outcrop I, Spain</td><td>Late/Upper Albian,</td><td>Ortega-Blanco & Engel, 2013</td></tr><tr><td>Megalopsenella poulloni</td><td>Burmese amber, Myanmar</td><td>Early/Lower Cenomanian</td><td>This study</td></tr><tr><td>Nucifrangibulum carentonensis Cockx, McKellar & Perrichot, 2016</td><td>Charentese Amber, Fouras, France</td><td>Early/Lower Cenomanian</td><td>Cockx et al., 2016</td></tr><tr><td>Sclerodermus quadridentatus Cockerell, 1917</td><td>Burmese amber, Myanmar</td><td>Early/Lower Cenomanian</td><td>Cockerell, 1917b</td></tr><tr><td>Uniceratops trex Colombo et al., 2020</td><td>Burmese amber, Myanmar</td><td>Early/Lower Cenomanian</td><td>Colombo et al., 2020</td></tr><tr><td>Zophepyris alavaensis Ortega-Blanco & Engel, 2013</td><td>Peñacerrada outcrop I, Spain</td><td>Late/Upper Albian,</td><td>Ortega-Blanco & Engel, 2013</td></tr></tbody></table>
wasp: the first tentatively assigned to †Protopristocerinae and the second assigned to †Holopsenellinae, based on general morphology. Both specimens highlight the underestimated diversity, the broad distribution and the evolution of the Bethylidae since the Cretaceous period.

# MATERIAL AND METHODS

## ORIGIN AND EXAMINATION OF MATERIAL

The two amber pieces containing the specimens studied herein derive from the deposits of Noije Bum in the Hukawng Valley (26°29' N, 96°35' E), Kachin State, northern Myanmar (see detailed map in: Grimaldi & Ross, 2017: fig. 2). Radiometric data established an Early Cenomanian age (98.79 ± 0.62 Mya) 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 bed, and within amber, corroborate a Late Albian/Early Cenomanian age of these sediments (Cruickshank & Ko, 2003; Yu et al., 2019).

Amber pieces were polished with a grinding polisher (Buehler EcoMet 30), using a fine silicon carbide sanding paper (grit size = 7000) or a diamond disk. The fragments were then embedded in sugar water between microscope slides to minimize the light scattering during observations. Specimens were examined with a Leica MZ APO stereomicroscope and a Nikon SMZ25 stereomicroscope. Photographs were made using a Nikon D800 digital camera mounted on a Nikon SMZ25 stereomicroscope. All images were digitally stacked photomicrographic composites of several individual focal planes, which were obtained using HeliconFocus 6.7 and Nikon Capture NXD. The figures were composed with Adobe Illustrator CC2018 and Photoshop CC2018.

The nomenclature and classification follow Azevedo et al. (2018). Main measurements and indices used are as follows: length of forewing (LFW); length of head (LH); width of head (WH); width of frons (WF); height of eye (HE); ocello-ocular line (OOL); width of ocellar triangle (WOT); diameter of anterior ocellus (DAO); vertex-ocular line (VOL). The nomenclature of integument sculpture follows Harris (1979).

## PHYLOGENETIC ANALYSIS

Cladograms have been built and indexes calculated with PAUP v.40b10 (Swofford, 2002), based on a 'branch and bound' method using maximum parsimony (MP) with tree bisection-reconnection (TBR) branch swapping, collapse of zero-length branches and equal weighting of all characters. If searches produced more than one tree, a strict consensus was performed to summarize data analyses. The list of character is available in Appendix 1 and the matrix of characters is available in Appendix

S1. We have used the list of 31 unordered and equally weighted characters proposed initially by Azevedo & Azar (2012). To this previous work we add six new taxa belonging to the subfamilies: †Holopsenellinae, †Lancepyrinae and †Protopristocerinae. In order to measure the branching patterns and robustness of parsimony trees, bootstrap analyses (bs) (Felsenstein, 1985; Hillis & Bull, 1993) were executed using the branch-and-bound option for 1000 replicates.

# RESULTS

## PHYLOGENETIC ANALYSIS

The set of parsimony trees from our analysis shows support for the putative placement of †Holopsenellinae as the 'plesiotypic'-most subfamily among Bethylidae, when our new and previously described genera and species are added to the matrix (Fig. 1). We recover four equally most-parsimonious cladograms for our complete dataset, which includes the two new genera described below and four additional taxa (L 46 steps; consistency index 0.673; retention index 0.857) (strict consensus tree with bootstrap values and synapomorphies: Fig. 1). There is strong support for the basalmost position of †Holopsenellinae (41% bootstrap) among Bethylidae, as part of a clade comprising *Holopsenella*, *Holopsenelliscus* and *Megalopsenella*. Additionally, the new genus *Cretapristocera*, tentatively placed among †Protopristocerinae, is coded into our matrix and seems to be close to †Lancepyrinae. These results suggest that the subfamilies †Protopristocerinae and †Lancepyrinae are close. However, *Cretapristocera* is the only †Protopristocerinae member clearly illustrated and figured, allowing a correct character coding. Forthcoming phylogenetic studies should clarify the position of the subfamily. Altogether, our findings show that a complete phylogeny, integrating fossil and extant representatives, is necessary.

With the addition of †Holopsenellinae to the analysis, the previous position of Bethylinae as the basalmost subfamily is no longer valid. However, Bethylinae appear to be basal to a clade comprising (Lancepyrinae + †Protopristocerinae + Mesitiinae + Pristocerinae + Epyrinae + Scleroderminae) with bootstrap value equal to 89, confirming previous hypotheses (Carr et al., 2010; Azevedo & Azar, 2012). Epyrinae seem to occupy a basal position to a clade comprising (Mesitiinae + Pristocerinae), with bootstrap value equal to 55, and Scleroderminae a basal position to a clade comprising (Epyrinae + (Mesitiinae + Pristocerinae)). Additionally, the coding of all the subfamilies is based on three genera for each subfamily; all of these systematically show a monophyly (bootstrap value relatively high, > 55) except for †Holopsenellinae
<figure><img src="image_2.png" /><figcaption>**Figure 1.** Strict consensus cladogram generated from phylogenetic analysis. Values above the branches represent bootstrap percentages > 50% (majority-rule consensus). Values under the branches represent major synapomorphies and character state.</figcaption></figure>

(bootstrap value < 50). Adding other genera to future studies may confirm this hypothesis.

SYSTEMATIC PALAEONTOLOGY

CLASS INSECTA LINNAEUS, 1758

ORDER HYMENOPTERA LINNAEUS, 1758

SUPERFAMILY CHRYSIDOIDEA LATREILLE, 1802

FAMILY BETHYLIDAE HALIDAY, 1839

(?) SUBFAMILY †PROTOPRISTOCERINAE NAGY, 1974

CRETAPRISTOCERA JOUAULT ET AL.

urn:lsid:zoobank.org:act:C89E2D10-E28F-4298-AC06-B20BCA318394.

Type species: *Cretapristocera longiscapa*.

*Etymology:* The generic name is composed of the Latin *creta*, chalk, used here in reference to the Cretaceous period and the genus *Pristocera* Klug, 1808, Pristocerinae, which it resembles. Gender feminine.

*Diagnosis:* Female fully winged; only cells 2R1 and R present; pterostigma narrow, elongate; antennae with ten flagellomeres; scape long; palpal formula 6-3; propodeum rectangular and not spinose; with stout femora.

CRETAPRISTOCERA LONGISCAPA JOUAULT ET AL.

(FIGS 2–4)

urn:lsid:zoobank.org:act:21A7CAEC-4250-45A9-A3B3-28F099EAEC25.
**Holotype:** Female, accession number IGR.BU-009, nearly complete and well-preserved female specimen in a rectangular piece of amber measuring 9 × 7 × 2.5 mm, together with a small Hymenoptera: Chalcidoidea; housed in the amber collection of the Geological Department and Museum (IGR) of the University of Rennes, France.

**Type locality and horizon:** Noije Bum Hill, Hukawng Valley, Kachin State, Myanmar; Lower Cenomanian, Upper Cretaceous.

**Etymology:** The specific epithet is derived from Latin *longus*, long, and *scapus*, shaft, for the elongated scape of this species.

**Description:** Female; body 2.1 mm long (as preserved), not depressed, almost smooth and not strongly foveolate; LFW 1.5 mm; castaneous; wings setose. LH 0.43 mm; WH 0.5 mm; WF 0.26 mm; HE 0.11 mm; OOL 0.25 mm; WOT 0.16 mm; DAO 0.04 mm; VOL 0.1 mm. Head not pubescent, with small, dorsal, median depression, finely punctuated but not sculptured; mandible with one strong and sharp tooth, projecting forward; six maxillary palpomeres, three (?) visible labial palpomeres; clypeus spined; antenna with ten flagellomeres with cylindrical cross-section; scape 0.37 × 0.07 mm, pedicel 0.13 × 0.04 mm (all measurements refer to length × width), F1 0.07 × 0.05 mm, F2 0.05 × 0.05 mm, F3 0.05 × 0.06 mm, F4 0.06 × 0.07 mm, F5 0.06 × 0.08 mm, F6 0.08 × 0.08 mm, F7 0.08 × 0.08 mm, F8 0.08 × 0.07 mm, F9 0.09 × 0.06 mm, F10 0.17 × 0.06 mm; occipital carina strongly marked; compound eye without microsetae; ocellar triangle not equilateral, with two posterior ocelli more distant from each other than from anterior. Mesosoma with dorsum smooth, not roughly sculptured; femora strongly thickened, tibia thin, tarsal claws simple; tibial spur formula 1-2-2; notauli well marked, posteriorly convergent; parapsidal furrows weak; metanotum developed medially and overlapping mesoscutellum posteriorly; metapectal-propodeal complex rectangular, not foveolate, with marginal carinae and no posterior spines; posterior margin of propodeum straight. Forewing covered with microsetae and bordered with small setae; anterior border not angularly incurved anterior to pterostigma; costal vein present; only veins C, Sc + R, Rs + M, 2r-rs&Rs, M + Cu, Cu and cells C (hardly visible), R and 2R1 present; vein cu-a absent and cell Cu opened; cell 2R1 distally opened; no basal stub of Rs + M; pterostigma long and narrow; poststigma abscissa of R1 short, spectral veins not visible. Hindwing

<figure><img src="image_3.png" /><figcaption>**Figure 2.** *Cretapristocera longiscapa*, holotype IGR. BU-009. A, habitus, in dorsal view. B, habitus, in ventral view. Scale bars: 0.5 mm.</figcaption></figure>

with only veins C and Sc + R and with three hamuli. Metasoma with short petiole; six tergites present (including three preserved detached from the body), T2 enlarged, convex, partly covering sternites; sting not preserved; length of clearly visible tergites: T1 0.23 mm, T2 0.29 mm, T3 at least 0.19 mm.

**Remarks:** It seems that the internal musculature of the fossil was preserved during the fossilization process, especially those of the legs (Figs 2–3). It could be interesting to compare the evolution of the musculature and the insertion of the muscles between the Cretaceous and extant Bethylidae in a future study, using 3D X-ray tomography.
<figure><img src="image_4.png" /><figcaption>**Figure 3.** *Cretapristocera longiscapa*, holotype IGR.BU-009. A, detailed ventral head view. B, detailed dorsal mesosomal view. C, wings. D, detailed view of leg preserved muscles. Scale bars: 0.5 mm.</figcaption></figure>

SUBFAMILY †HOLOPSENELLINAE ENGEL ET AL., 2016

MEGALOPSENELLA JOUAULT ET AL.

urn:lsid:zoobank.org:act:081F52D1-5240-4FC0-B022-66BE5E7CFB74.

Type species: *Megalopsenella pouilloni*.

*Etymology:* The generic name is composed of the Greek prefix μεγάλο, large, and the ending of the name Holopsenella *Engel et al., 2016*, in turn derived from ψινέλλα, brushes. Gender feminine.

*Diagnosis:* Female, antennae with 11 flagellomeres; mandibles long; propodeum nearly straight, without propodeal spines and sculpture; notauli slightly impressed; stout femora; forewing cell 1R1, broad and short, with vein Rs clearly shorter than Rs + M; cell 2R1 elongate, nearly reaching wing apex; distal part of

Rs straight, making angle with straight 2r-rs; hindwing with 5 hamuli.

MEGALOPSENELLA POUILLONI JOUAULT ET AL.

(FIGS 5, 6)

urn:lsid:zoobank.org:act:578342A1-78A5-4F5E-9A08-E5D3E1B46A83.

*Holotype:* Female, accession number Po55 (complete and well-preserved female specimen in a rounded piece of amber measuring 20 × 20 × 5 mm, without syninclusions), housed in the Musée d'Histoire Naturelle de Colmar, France.

*Type locality and horizon:* Noije Bum Hill, Hukawng Valley, Kachin State, Myanmar; Lower Cenomanian, Upper Cretaceous.
<figure><img src="image_5.png" /><figcaption>**Figure 5.** *Megalopsenella pouilloni*, holotype Po55. A, habitus, in left lateral view. B, habitus, in right ventral view. Scale bars: 1 mm.</figcaption></figure>

femora strongly thickened; tibia thin, pretarsal claws with strong subapical tooth; tibial spur formula 1-1-2; notauli weakly marked; parapsidal furrows very weak; mesoscutellum smooth; metapectal-propodeal complex flat, rectangular, not foveolate, and with no posterior spines; posterior margin of propodeum straight.

Forewing covered with microtrichia and bordered with small setae; anterior border not angularly incurved anterior to pterostigma; seven closed cells present, and all veins C, Sc + R, Rs, M + Cu, Cu, A tubular; pterostigma rather broad; poststigmal abscissa of R1 long; hindwing 3.23 mm long with five hamuli. *Metasoma* c. 5.76 mm long, with short petiole; length of clearly visible tergites: T1 1.45 mm, T2 1 mm, T3 at least 0.8 mm; short part of sting visible.

# DISCUSSION

## SYSTEMATIC PLACEMENT

Following the key to the bethylid subfamilies of *Azevedo et al.* (2018), *Cretapristocera* would be identified as Pristocerinae because of the following characters: winged; forewing with Rs + M vein absent; metanotum developed medially and overlapping mesoscutellum posteriorly. Nevertheless, *Cretapristocera* differs from all extant Pristocerinae by having only ten flagellomeres, instead of 11. A few characteristics strongly suggest that this specimen is a female, including: metasoma only possessing six tergites and shape of mandibles, which only have one sharp apical tooth (similar to those of *Apenesia* and *Cleistepyris*, while males have mandibles with several teeth; see: *Azevedo et al.* (2018: figs 22H, 26H)). Extant female Pristocerinae are apterous, while females of the fossil group †Protopristocerinae are fully winged, as in *Cretapristocera* (Cockerell, 1917a; Brues, 1923, 1933; Nagy, 1974; Falières & Nel, 2019). However, they also have 11 flagellomeres. *Cretapristocera* shares with members of †Protopristocerinae the following characters: 2R1 cell opened apically, pterostigma elongate, narrow (two characters also present in the Pristocerinae); second metasomal segment enlarged; metasomal sterna unarmed (*Azevedo et al.*, 2018; Falières & Nel, 2019). In contrast, cell 1Cu cell is distally opened, while it is closed and much longer than the R cell in Pristocerinae and †Protopristocerinae.

KEY TO GENERA OF †HOLOPSENELLINAE (MODIFIED FROM ENGEL, 2019)

1. Clypeus with apical margin unmodified; first metasomal tergum without transverse carina....................2

- Clypeus with apical margin modified and medially emarginate; first metasomal tergum with transverse carina sometimes present [Early Cretaceous (Barremian): Lebanon] ....................................................................3

2. Anterior wing margin beyond pterostigma swollen (margin discontinuous); second cubital cell open; pretarsal claws simple (Cenomanian: Myanmar).................................................*Holopsenelliscus Engel, 2019*

- Anterior wing margin beyond pterostigma not swollen (margin continuous); second cubital cell closed; pretarsal claws dentate (Santonian: Taimyr amber, Russia)............................................ *Cretabythus Evans, 1973*

3. Antennae with ten flagellomeres; forewings with cell 2R1 short, ending far from wing apex; veins Rs and 2r-rs curved; propodeum with propodeal spines (Cenomanian: Myanmar) ....................*Holopsenella Engel et al., 2016*

- Antennae with 11 flagellomeres; forewings with cell 2R1 elongate, nearly reaching wing apex; veins Rs and 2r-rs straight; propodeum without propodeal spines (Cenomanian: Myanmar) ...... *Megalopsenella*
<figure><img src="image_6.png" /><figcaption>**Figure 6.** *Megalopsenella pouilloni*, holotype Po55. A, head detailed ventral view. B, fore and hindwings with nomenclature of cells (in bold) and veins. C, line drawing of habitus in right ventral view. Scale bars: 1 mm.</figcaption></figure>

In conclusion, the exact affinities of *Cretapristocera* remain somewhat uncertain, mainly because the monophyly of †Protopristocerinae has not been demonstrated. We provisionally include *Cretapristocera*

in †Protopristocerinae, while it might belong to the stem group of Pristocerinae.

*Bethylitella cylindrella* Cockerell, 1917 (also from 'Mid'-Cretaceous Burmese amber) is a poorly known
taxon that is currently attributed to †Protopristocerinae (Cockerell, 1917a; Ross & York, 2000: fig. 19). Cockerell (1917a: 365) suggested that the type is a female, on the basis of the shape of the head, which is similar to that of the 'female *Isobrachium*', while its abdomen is not preserved. It differs from *Cretapristocera* in having 11 flagellomeres, while it also has a reduced forewing venation.

Following the key to the bethylid subfamilies of Azevedo et al. (2018), *Megalopsenella* would fall within the †Holopsenellinae, because of the following characters: it is winged; the forewing has a tubular Rs + M vein, at least as a stub, with seven closed cells. This Mesozoic subfamily only comprises the two genera *Holopsenella* Engel et al., 2016 (Early Cretaceous Lebanese amber) and *Cretabythus* Evans, 1973 (Late Cretaceous Taimyr amber). *Megalopsenella* differs from both in the shape of the cell 1R1, which is broader and shorter in *Megalopsenella*, with vein Rs clearly shorter than Rs + M; cell 2R1 elongate, nearly reaching the wing apex, and the distal part of Rs straight, making an angle with the straight 2r-rs (while both are curved in *Holopsenella* and *Cretabythus*). The type female of *Megalopsenella* has 11 flagellomeres, while the type female of *Holopsenella* has ten. The mandibles of *Megalopsenella* are long, while they are described as short in *Holopsenella*. The propodeum of *Megalopsenella* is nearly straight and without propodeal spines, while it is concave with small propodeal spines in *Holopsenella*. *Megalopsenella* has the notauli slightly impressed, while they are distinctly impressed in *Cretabythus*. The propodeum of *Megalopsenella* has no sculpturing, unlike that of *Cretabythus*. *Megalopsenella* has stout femora, unlike *Cretabythus*. Engel (2019) recently described a new genus of Holopsenellinae from Burmese amber: *Holopsenelliscus*. Following the key proposed by Engel (2019), *Megalopsenella* keys out near *Holopsenelliscus* and *Cretabythus*. However, *Megalopsenella* differs from *Holopsenelliscus* in having antennal toruli that are partially closed by projected expansions of the head capsule; long mandibles; stout femora; forewing with first radial cell shorter and thinner, while the second radial 1 cell is elongated; hindwing with five hamuli; and pretarsal claws with a strong subapical tooth. Together these characteristics allow clear differentiation between both genera.

## PALAEOGEOGRAPHICAL AND PALAEOECOLOGICAL IMPLICATIONS

Recently, Westerweel et al. (2019) suggested an island endemism for some taxa of the Burmese amber biota. These results confirmed the hypothesis formulated previously by Rasnitsyn & Ohm-Kühnle (2018), even if some other terrestrial organisms suggest that this biota had some contact with other areas (Oliveira et al., 2016). The description of numerous

other hymenopteran families, only known from the Burmese amber assemblage (Zhang et al., 2018), highlight a possible allopatric speciation. These observations may be extended to the order level. Among Insecta, some orders have been recorded only from Burmese amber, for example †Alienoptera (Bai et al., 2016, 2018) and †Tarachoptera (Mey et al., 2017), which are currently considered to be endemic. This is not the case for †Holopsenellinae, which show a wide distribution during the Cretaceous. The three other holopsenelline species that are known were described from Taimyr, Burmese and Lebanese amber (Table 1). The description of *Megalopsenella pouilloni* suggests that the subfamily was already well distributed on the North Tethysian continent and islands. It is, therefore, likely that new representatives of this subfamily will be found in the Cretaceous amber deposits of Canada, France, Spain and the USA.

The recent study of Yu et al. (2019) supported the model of an estuarine, coastal landscape for this ‘Mid’-Cretaceous amber forest. Previously, Grimaldi et al. (2002) considered that the environment must have been tropical within an average temperature range of 32–55 °C. This estimate, in conjunction with the observations of Yu et al. (2019), could indicate a tropical coastal zone dominated by araucarian conifers (Poinar et al., 2007). It is conceivable that bethylid wasps were present and well diversified in this type of environment, as they are also diverse in such habitats at the present. Moreover, all extant host taxa (Azevedo et al., 2018) were already well diversified when Burmese amber formed, viz., Coleoptera with more than 80 families and 207 species [among others, Cerambycidae (Lin & Bai, 2017) and Bostrichidae (Legalov, 2018)]; Lepidoptera with four families (Ross, 2019) [Gelechiidae and a majority of Micropterigidae (Ngô-Muller et al., 2020)] and Hymenoptera with more than 48 families (Ross, 2019). These data suggest that Bethylidae were already well diversified during the ‘Mid’-Cretaceous.

## PHYLOGENY, EVOLUTION AND REDUCTION OF WING VENATION

Despite several recent taxonomic revisions and new descriptions, the phylogeny of Bethylidae is not up to date. In view of all the recent descriptions and, in particular, the two fossil subfamilies †Holopsenellinae (Engel et al., 2016) and †Lancepyrinae (Azevedo & Azar, 2012) that have been erected, a phylogenetic study of the family integrating these taxa is necessary. Bethylinae is currently considered as a ‘plesiotypic’ subfamily among the bethylid wasps (Carr et al., 2010; Azevedo & Azar, 2012), while †Holopsenellinae has not been integrated in these previous studies.
Our phylogenetic analysis suggests that the †Holopsenellinae may indeed be a good candidate as the basalmost subfamily among Bethylidae. All †Holopsenellinae display a complete forewing venation with numerous cells (Fig. 7) and antenna with numerous flagellomeres (Figs 5, 6), generally considered as 'ancestral' among Hymenoptera. *Engelet al.* (2016) even suggested that characters separating †Holopsenellinae from Plumariidae might be symplesiomorphic and may require placing Plumariidae as a subfamily of Bethylidae. The diagnostic characters of Plumariidae as proposed by *Goulet & Huber* (1993) are mostly shared with †Holopsenellinae: antenna with 11 (rarely ten) flagellomeres (shared with Holopsenellinae); pronotum without anterior flange (hardly visible on our specimen); sexual dimorphism extreme with male macropterous (as in †Holopsenellinae; see: Evans, 1973: Fig. 5) but female apterous (not in †Holopsenellinae Fig. 5; see: *Engel et al.*, 2016: figs 1, 2); pronotum horizontal (as in *Megalopsenella pouilloni*; see Fig. 5); mesothorax separated from metathorax by deep ventral (and lateral) constriction (hardly visible in †Holopsenellinae); hindwing with at least two cells enclosed by tubular veins (likely a plesiomorphy), while Evans (1973) mentioned the lack of a closed cell on the hindwing of *Cretabythus sibiricus* Evans, 1973; head prognathous (shared with †Holopsenellinae); pronotum horizontal (as in *Megalopsenella pouilloni*; see Fig 5); mesothorax separated from metathorax by deep ventral (and lateral) constriction (hardly visible in †Holopsenellinae). Only a few diagnostic characters differ between †Holopsenellinae and Plumariidae, and these differences may be modulated in the future by descriptions of additional holopsenelline wasps. However, Plumariidae are supposed to be distinguishable from other Chrysidoidea in having flagellomeres with long, erect setae, at least half as long as the width of each flagellomere (*Goulet & Huber*, 1993: 132), but this character is not present in all genera. *Pluroides Diez et al.*, 2010 has setae 0.25 times as long as width of the flagellomere (*Diez et al.*, 2010). This character is also present in some Bethylidae (viz. *Goniozus* sp.; *Azevedo et al.*, 2018: fig. 14F) and may be linked to prey detection. The character might have limited value for family characterization.

The general trend among various hymenopteran lineages is the reduction and simplification of the ancestral condition of complex wing venation. This trend is observed in both Aculeata and Apocrita (non-Aculeata), viz. the evanioid family †Praeaulacidae (*Li et al.*, 2015: fig. 5.). *Rasnitsyn* (1969, 1980) proposed a general trend consisting of the miniaturization, venational reduction, enlargement of pterostigma and reduction of number of the antennal flagellomeres. These modifications often occur together and form a

<figure><img src="image_7.png" /><figcaption>**Figure 7.** Evolution of forewings venation among †Holopsenellinae. A, *Holopsenella primotica* *Engel et al.*, 2016. B, *Megalopsenella pouilloni*. C, *Holopsenelliscus pankowskiorum*. D, *Cretabythus sibiricus* (modified from: Evans, 1973; *Engel et al.*, 2016; *Engel*, 2019). Scale bars: 0.5 mm (A, C, D); 1 mm (B).</figcaption></figure>

morphological syndrome characteristic of moderately small Hymenoptera (*Li et al.*, 2015). This trend is also present in bethylid wasps and may be observed by comparing the venations of Cretaceous taxa to those of Eocene and Miocene taxa. This reduction may also be observed among †Holopsenellinae (Fig. 7) with the opening of cell 2Cu, which is closed in Barremian species (Fig. 7A) but opened in Cenomanian–Santonian species (Fig. 7B–D). Variation in the flagellomere number is less common than in wing venation (CJ, pers. obs.). It is, therefore, more difficult to observe variation between taxa from the same geological period, which is the case for
the †Holopsenellinae (only known from Cretaceous deposits). Meanwhile, a comparison between specimens from different geological times clearly highlights these modifications. Similar losses are observed in Scleroderminae, with a disappearance or simplification of the veins surrounding the R and 1Cu cells (Fig. 8) (Colombo & Azevedo, 2019). This disappearance is more obvious in Scleroderminae than in the †Holopsenellinae, which is in line with the two species used in the comparison being separated by more than 40 Myr, i.e. Late/Upper Santonian vs. Priabonian (Evans, 1973; Sorg, 1988).

Additionally, according to Engel et al. (2016), similar vein reductions are observed in †Falsiformicidae, which also belong to the Chrysidoidea. After examination of †Falsiformicidae from Burmese, French and Lebanese Cretaceous deposits, it appears that the reduction in wing venation is visible for the first medial and first radial cells (CJ pers. obs.). A study in preparation (Perrichot et al., in prep.) on this family may confirm these trends. Our observations strengthen the basal position of †Holopsenellinae among the Bethylidae, and suggest that the bethylid wasps have evolved from an ancestor with complex wing venation, numerous flagellomeres and maybe a macropterous male and female. However, the relationships between Bethylidae and the other Chrysidoidea is in need of a revision, particularly to clarify the placement of †Falsiformicidae (Perrichot et al., 2014; Engel et al., 2016).

<figure><img src="image_8.png" /><figcaption>**Figure 8.** Evolution of fore wings venation among Scleroderminae. A, *Celonophamia taimyria*. B, *Plastanoxus atrescens* (modified from: Evans, 1973; Sorg, 1988). Scale bars: 0.5 mm (A); 0.2 mm (B).</figcaption></figure>

## CONCLUSIONS

The descriptions of *Cretapristocera longiscapa* and *Megalopsenella pouilloni* suggest a high diversity of bethylid wasps during the Cretaceous period and expand the fossil record of the family to six representatives in Burmese amber. Our findings also propose putative plesiomorphic character states (viz. numerous flagellomeres and a complete forewing venation in *Megalopsenella pouilloni*), which may help clarify future phylogenies. The presence of *Cretapristocera longiscapa* and *Megalopsenella pouilloni* in Burmese amber extend the range of the †Holopsenellinae to all the North Tethysian continents and strengthen the presence of the †Protopristocerinae in the Burmese amber biota. The description of these new taxa allows us to strengthen the hypothesis of a global trend among Hymenoptera consisting of a reduction of wing venation over the course of geological times. It also appears that the relationships between the subfamilies composing Bethylidae, and the other extant and extinct chrysidoid families, need further study to clearly establish the relationships between and among the families composing the Chrysidoidea.

## ACKNOWLEDGEMENTS

We sincerely appreciate critical reviews and comments from the editor Maarten Christenhusz and three anonymous reviewers in improving our manuscript.

## REFERENCES

* **Azevedo CO, Azar D.** 2012. A new fossil subfamily of Bethylidae (Hymenoptera) from the Early Cretaceous Lebanese amber and its phylogenetic position. *Zoologia* 29: 210–218.

* **Azevedo CO, Alencar IDCC, Ramos MS, Barbosa DN, Colombo WD, Vargas JMR, Lim J.** 2018. Global guide of the flat wasps (Hymenoptera, Bethylidae). *Zootaxa* 4489: 1–294.

* **Bai M, Beutel RG, Klass K-D, Zhang W, Yang X, Wipfler B.** 2016. Alienoptera – a new insect order in the roach-mantodean twilight zone. *Gondwana Research* 39: 317–326.

* **Bai M, Beutel RG, Zhang WW, Wang S, Hörnig M, Gröhn C, Yan E, Yang XK, Wipfler B.** 2018. A new Cretaceous insect with a unique cephalo-thoracic scissor device. *Current Biology* 28: 438–443.

* **Brothers DJ.** 1999. Phylogeny and evolution of wasps, ants and bees (Hymenoptera, Chrysidoidea, Vespoidea and Apoidea). *Zoologica Scripta* 28: 233–249.

* **Brothers DJ, Carpenter JM.** 1993. Phylogeny of Aculeata: Chrysidoidea and Vespoidea (Hymenoptera). *Journal of Hymenoptera Research* 2: 227–304.
**Brues CT. 1923.** Some new fossil parasitic Hymenoptera from Baltic amber. *Proceedings of the American Academy of Arts and Sciences* **58**: 327–346.

**Brues CT. 1933.** The parasitic Hymenoptera of the Baltic amber. Part 1. *Bernstein-Forschungen (Amber Studies)* **3**: 4–179.

**Carr M, Young JPW, Mayhew PJ. 2010.** Phylogeny of bethylid wasps (Hymenoptera: Bethylidae) inferred from 28S and 16S rRNA genes. *Insect Systematics and Evolution* **41**: 55–73.

**Cockerell TDA. 1917a.** Arthropods in Burmese amber. *American Journal of Science ser. 4* **44**: 360–368.

**Cockerell TDA. 1917b.** Arthropods in Burmese amber. *Psychhe* **24**: 40–44.

**Cockerell TDA. 1920.** Fossil arthropods in the British Museum, I. *Annals and Magazine of Natural History ser. 9* **5**: 273–279.

**Cockx PFD, McKellar RC, Perrichot V. 2016.** First records of the subfamilies Bethylinae (Hymenoptera: Bethylidae) and Cleptinae (Hymenoptera: Chrysididae) in Upper Cretaceous amber from France. *Cretaceous Research* **68**: 1–8.

**Colombo WD, Azevedo CO. 2019.** Synopsis of the fossil Scleroderminae (Hymenoptera, Bethylidae) with description of a new genus and four new species from Baltic amber. *Historical Biology* **31**: 1–10.

**Colombo WD, Gobbi FT, Perkovsky EE, Azevedo CO. 2020.** Synopsis of the fossil Pristocerinae (Hymenoptera, Bethylidae), with description of two new genera and species from Burmese, Taimyr, Baltic and Rovno ambers. *Historical Biology*. Doi: https://doi.org/10.1080/08912963.2020.1733551.

**Cruickshank RD, Ko K. 2003.** Geology of an amber locality in the Hukawng Valley, northern Myanmar. *Journal of Asian Earth Sciences* **21**: 441–455.

**Diez PA, Roig-Alsina A, Fidalgo P. 2010.** Phylogenetic relationships of *Pluroides porteri*, a new genus and species of Plumariidae from Argentina (Hymenoptera: Chrysidoidea). *Journal of Hymenoptera Research* **19**: 113–120.

**Engel MS. 2019.** A holopsenelline wasp in mid-Cretaceous amber from Myanmar (Hymenoptera: Bethylidae). *Palaeoentomology* **2**: 199–204.

**Engel MS, Ortega-Blanco J, Azevedo CO. 2016.** A new bethylid wasp in Lebanese Early Cretaceous amber (Hymenoptera: Chrysidoidea), with comments on other Mesozoic taxa. *American Museum Novitates* **3855**: 1–14.

**Evans HE. 1973.** Cretaceous aculeate wasps from Taimyr, Siberia (Hymenoptera). *Psychhe* **80**: 166–178.

**Falières E, Nel A. 2019.** The first representative of the extinct flat wasp subfamily Protopristocerinae (Insecta: Hymenoptera, Bethylidae). *Palaeoentomology* **2**: 322–326.

**Felsenstein J. 1985.** Confidence limits on phylogenies: an approach using the bootstrap. *Evolution* **39**: 783–391.

**Gauld ID, Bolton B. 1988.** *The Hymenoptera*. London and Oxford: British Museum (Natural History) and Oxford University Press, 332.

**Gordh G, Móczár L. 1990.** A catalog of the world Bethylidae (Hymenoptera: Aculeata). *Memoirs of the American Entomological Institute* **46**: 1–364.

**Goulet H, Huber JT. 1993.** *Hymenoptera of the world: an identification guide to families*. Ottawa: Agriculture Canada, 680.

**Grimaldi D, Ross A. 2017.** Extraordinary Lagerstätten in amber, with particular reference to the Cretaceous of Burma. In: Fraser NC, Sues H-D, eds. *Terrestrial conservation Lagerstätten: windows into the evolution of life on land*. Edinburgh: Dunedin Academic Press, 287–342.

**Grimaldi DA, Engel MS, Nascimbene PC. 2002.** Fossiliferous Cretaceous amber from Myanmar (Burma): its rediscovery, biotic diversity, and paleontological significance. *American Museum Novitates* **3361**: 1–72.

**Haliday AH. 1839.** Hymenoptera Brittannica Oxyura. *Entomological Magazine* **3**: 5–15.

**Harris RA. 1979.** The glossary of surface sculpturing. *Occasional Papers in Entomology, California Department of Food and Agriculture Laboratory Services Supplement* **28**: 1–31.

**Hillis DM, Bull JJ. 1993.** An empirical test of bootstrapping as a method for assessing confidence in phylogenetic analysis. *Systematic Biology* **42**: 182–192.

**HOL. 2020.** *Hymenoptera Online*. Columbus: Ohio State University. Available at: https://hol.osu.edu (accessed 25 January 2020).

**Legalov AA. 2018.** New auger beetle (Coleoptera; Bostrichidae) from mid-Cretaceous Burmese amber. *Cretaceous Research* **92**: 210–213.

**Li LF, Rasnitsyn AP, Shih C-K, Ren D. 2015.** A new genus and species of Praeaulacidae (Hymenoptera: Evanioidea) from Upper Cretaceous Myanmar amber. *Cretaceous Research* **55**: 19–24.

**Lin M-Y, Bai M. 2017.** *Qitianniu zhihaoi* gen. et sp. nov.: the first cerambycid beetle found in Cretaceous Burmese amber (Coleoptera: Chrysomeloidea). *Cretaceous Research* **75**: 173–178.

**Mao M, Gibson T, Dowton M. 2015.** Higher-level phylogeny of the Hymenoptera inferred from mitochondrial genomes. *Molecular Phylogenetics and Evolution* **84**: 34–43.

**McKellar RC, Engel MS. 2014.** New bethylid and chrysidid wasps (Hymenoptera: Chrysidoidea) from Canadian Late Cretaceous amber. *Palaeontologische Zeitschrift* **88**: 433–451.

**Melo GAR, Evans HE. 1993.** Two new *Microstigmus* species (Hymenoptera, Sphecidae), with description of their parasite, *Goniozus microstigmii* sp. n. (Hymenoptera, Bethylidae). *Proceedings of the Entomological Society of Washington* **92**: 258–263.

**Mey W, Wichard W, Müller P, Wang B. 2017.** The blueprint of the Amphiesmenoptera—Tarachoptera, a new order of insects from Burmese amber (Insecta, Amphiesmenoptera). *Fossil Record* **20**: 129–145.

**Nagy CG. 1974.** A new bethylid subfamily allied to Protopristocerinae (Bethylidae). *Bolletino della Societa Entomologica Italiana* **106**: 126–129.

**Ngô-Muller V, Garrouste R, Pouillon J-M, Nel A. 2020.** A new micropterigid moth from the 'mid'-Cretaceous Burmese amber (Insecta: Lepidoptera). *Cretaceous Research* **109**: 1–6.

**Oliveira I de S, Bai M, Jahn H, Gross V, Martin C, Hammel JU, Zhang W-W, Mayer G. 2016.** Earliest
onychophoran in amber reveals Gondwanan migration patterns. *Current Biology* **26**: 2594–2601.

**Ortega-Blanco J, Engel MS. 2013.** Bethylidae from Early Cretaceous Spanish amber (Hymenoptera: Chrysidoidea). *Journal of the Kansas Entomological Society* **86**: 264–276.

**Perrichot V, Engel MS, Nel A, Ortega-Blanco J, Delclos X, Soriano C, Lohrmann V, Tafforeau P. 2014.** "False ants" from the Cretaceous (Hymenoptera: Chrysidoidea: Falsiformicidae). *Mitteilungen des Entomologischen Vereins* **49**: 26.

**Peters R, Krogmann L, Mayer C, Donath A, Gunkel S, Meusemann K, Kozlov A, Podsiadlowski L, Petersen M, Lanfear R, Diez P, Heraty J, Kjer K, Klopfstein S, Meier R, Polidori C, Schmitt T, Liu S, Zhou X, Niehuis O. 2017.** Evolutionary history of the Hymenoptera. *Current Biology* **27**: 1013–1018.

**Poinar GO, Lambert JB, Wu Y. 2007.** Araucarian source of fossiliferous Burmese amber: spectroscopic and anatomical evidence. *Journal of the Botanical Research Institute of Texas* **1**: 449–455.

**Rasnitsyn AP. 1969.** The origin and evolution of Lower Hymenoptera. *Transactions of the Paleontological Institute, Academy of Sciences of the USSR* **123**: 1–196 [In Russian].

**Rasnitsyn AP. 1980.** [Origin and evolution of Hymenoptera]. *Transactions of the Paleontological Institute, Academy of Sciences of the USSR* **174**: 1–192 [in Russian].

**Rasnitsyn AP. 1990.** Hymenoptera. In: Ponomarenko AG, ed. *Late Mesozoic insects of eastern Transbaikalia*. Moscow: Nauka, 177–205.

**Rasnitsyn AP, Ohm-Kühnle C. 2018.** Three new female *Aptenoperissus* from mid-Cretaceous Burmese amber (Hymenoptera, Stephanoidea, Aptenoperissidae): unexpected diversity of paradoxical wasps suggests insular features of source biome. *Cretaceous Research* **91**: 168–175.

**Ross, AJ. 2019.** Burmese (Myanmar) amber checklist and bibliography 2018. *Palaeoentomology* **2**: 22–84.

**Ross, AJ, York, PV. 2000.** A list of type and figured specimens of insects and other inclusions in Burmese amber. *Bulletin of the Natural History Museum, Geology* **56**: 11–20.

**Shi G, Grimaldi DA, Harlow GE, Wang J, Wang J, Yang M, Lei W, Li Q, Li X. 2012.** Age constraint on Burmese amber based on U-Pb dating of zircons. *Cretaceous Research* **37**: 155–163.

**Sorg M. 1988.** Zur Phylogenie und Systematik der Bethylidae (Insecta: Hymenoptera, Chrysidoidea). *Sonderveröffentlichungen des Geologischen Instituts der Universität Köln* **63**: 1–146.

**Swofford DL. 2002.** *PAUP: phylogenetic analysis using parsimony (and other methods)*, v.4.0 Beta 10. Sunderland: Sinauer Associates.

**Tang P, Zhu J-C, Zheng B-Y, Wei S-J, Sharkey M, Chen X-X, Vogler AP. 2019.** Mitochondrial phylogenomics of the Hymenoptera. *Molecular Phylogenetics and Evolution* **131**: 8–18.

**Westerweel J, Roperch P, Licht A, Dupont-Nivet G, Win Z, Poblete F, Ruffet G, Swe H-H, Thi M-K, Aung D-W. 2019.** Burma terrane part of the Trans-Tethyan arc during collision with India according to palaeomagnetic data. *Nature Geoscience* **12**: 863–868.

**Yu T, Kelly R, Mu L, Ross A, Kennedy J, Broly P, Xia F, Zhang H, Wang B, Dilcher D. 2019.** An ammonite trapped in Burmese amber. *Proceedings of the National Academy of Sciences of the USA* **116**: 11345–11350.

**Zhang Q, Rasnitsyn AP, Zhang Hc. 2018.** Peleserphidae, a new family of basal proctotrupomorphs (Hymenoptera: Proctotrupoidea) from mid-Cretaceous Burmese amber. *Cretaceous Research* **86**: 66–72.

## SUPPORTING INFORMATION

Additional Supporting Information may be found in the online version of this article at the publisher's web-site.

**Appendix S1. Matrix of characters.**

## APPENDIX

List of characters (after Azevedo & Azar, 2012):

1. Clypeal intrafrontal extension: (0) absent; (1) present.

2. Scape length: (0) long (more than 2 × longer than pedicel); (1) short (less than 2 × longer than pedicel).

3. Pedicel length: (0) longer than wider; (1) shorter than wide.

4. Eye size: (0) large (HE more than 0.25 × LH); (1) reduced (HE less than 0.25 × LH).

5. Present of ocelli: (0) present; (1) absent.

6. Antennal socket size: (0) reduced (less than 0.5 × as long as wide); (1) projected (more than 0.5 × as long as wide).

7. Flatness of inter-torular space: (0) depressed; (1) bulging.

8. Presence of occipital carina: (0) absent; (1) present.

9. Presence of post-genal carina: (0) absent; (1) present.

10. Dorsal pronotal disc shape: (0) wide anteriorly; (1) narrow anteriorly.

11. Dorsal pronotal disc length: (0) short (shorter than mesoscutum); (1) long (shorter than mesoscutum).

12. Prosternum size: (0) large (when larger than forecoxa); (1) small (smaller than forecoxa).

13. Posterior margin of pronotal disc: (0) evenly concave; (1) convex medially.

14. Scutellar groove: (0) present; (1) absent.

15. Metanotum: (0) with median fovea; (1) without median fovea.
16. Metapectal–propodeal complex, spine of posterior corner: (0) absent; (1) present.

17. Position of foretrochanter insertion: (0) medially at coxa; (1) apically at coxa.

18. Claw shape: (0) curved; (1) angled.

19. Presence of tegulae: (0) present; (1) absent.

20. Presence of wings: (0) present; (1) absent.

21. Shape of anterior margin of forewing: (0) straight; (1) concave.

22. Openness of second radial 1 cell of forewing: (0) closed (completely surrounded by tubular veins); (1) opened (not completely surrounded by tubular veins).

23. Profile of post-stigma area of anterior margin of forewing: (0) straight; (1) slightly curved.

24. First medial cell shape: (0) rectangular; (1) pentagonal.

25. Conspicuousness of Rs + M: (0) tubular; (1) spectral.

26. M + Rs vein shape: (0) angled; (1) almost straight.

27. cu-a vein shape: (0) slightly arched; (1) arched posteriorly.

28. Presence of costal vein: (0) present; (1) absent.

29. Costal cell width: (0) wide (wider than stigma); (1) narrow (narrower than stigma).

30. Metasomal petiolar root differentiation: (0) absent; (1) present.

31. Size of second metasomal tergite: (0) regular sized; (1) much larger than other tergites.