﻿A new species of beaded lacewings (Neuroptera, Berothidae) from mid-Cretaceous Myanmar amber

﻿Abstract A new species of Berothidae, Jersiberothamusivum sp. nov., is described and illustrated from mid-Cretaceous (lowest Cenomanian) Myanmar amber. It is easily distinguished from other species of Berothidae by the configuration of the wing venation including: forewing with distinct areas of infuscation surrounding cross-veins and vein forks, all cross-veins simple prior to ScP-RA fusion, presence of two cross-veins ra-rp; absence of inner or outer graduate series of cross-veins; RP with three branches; and absence of ma-mp cross-veins and cua-cup cross-veins; while hind wing has cross-vein 1r-m absent. The previous diagnoses of Iceloberotha Grimaldi, 2000 and Jersiberotha Grimaldi, 2000 are quite unclear because some characters occur mosaically in both genera. In order to solve this problem and distinguish J.musivum from other species in the family, a new key to species of Berothidae from Myanmar amber has been provided and the diagnoses of Iceloberotha and Jersiberotha have been revised.


Introduction
The family Berothidae, commonly known as beaded lacewings, together with Mantispidae and Rhachiberothidae, belongs to the superfamily Mantispoidea, which represents one of the major lineages of the crown group of Neuroptera Engel et al. 2018;Winterton et al. 2018). The extant Berothidae are distributed in all zoogeographical regions and currently comprise less than 130 described species of 28 genera worldwide (Oswald 2019). The genus Jersiberotha was firstly erected by Grimaldi from the New Jersey amber for sharing the wing characters: two adjacent ra-rp cross-veins in the forewing, only one ma-mp cross-vein (Grimaldi 2000). Engel and Grimaldi (2008) described two other species (J. myanmarensis and J. tauberorum) and a related genus Iceloberotha from Myanmar amber.
Molecular evidence suggested the Berothidae might have diverged during the Late Triassic . Winterton et al. (2018) and Vasilikopoulos et al. (2020) estimated the divergence between Beorthidae and Mantispidae was in the Early Jurassic, although the oldest definite fossil of Berothidae was reported from the Middle Jurassic (Makarkin et al. 2011). So far, there are about 27 genera and 41 species of fossil berothids described from the Middle Jurassic to late Eocene (Yang et al. 2019;Fuente et al. 2021). The amber from Myanmar is one of the most intensively studied objects amongst Cretaceous fossiliferous resins and contains a remarkably diverse flora and fauna (Grimaldi et al. 2002). It is remarkable that the palaeodiversity of Berothidae is extraordinarily rich from the mid-Cretaceous of Myanmar, being one of the major Neuropteran lineages in this deposit (Ross 2019), with 13 genera and 19 species described, based on the Myanmar amber specimens (Engel and Grimaldi 2008;Yuan et al. 2016;Huang et al. 2018;Makarkin 2018;Yang et al. 2019;Yang et al. 2020). These Myanmar amber berothids show diverse morphological characters and are probably the members, or as the stem-groups of different subfamilies (Huang et al. 2018).
Herein, a new species of Jersiberotha Grimaldi, 2000 is described, based on a wellpreserved female specimen from the mid-Cretaceous (ca. 98.8 Ma) of Myanmar. In addition, a revised key to the species of Berothidae from Myanmar amber has been provided. The diagnoses of Iceloberotha and Jersiberotha also have been revised.

Materials and methods
This study is based on a single, female specimen preserved in a piece of clear, yellowish Myanmar amber, which was collected from an amber mine, located in the Hukawng Valley of Kachin Province, Myanmar (Chen et al. 2019). The age of Myanmar amber in this investigation is radiometrically dated at 98.79 ± 0.62 Ma, based on U-Pb zircon dating of the volcanoclastic matrix (Shi et al. 2012). However, it is important to highlight that the Zircon date only gives the age of the top bed and a minimum age for the amber, so the geologic age of Myanmar amber may be slightly older than the Zircon date.
The amber piece that contains the inclusions was cut and polished with different grain sizes of sandpaper and finally buffed with polishing powder. The specimen is housed in the Institute of Paleontology and Stratigraphy, School of Earth Sciences, Lanzhou University, Gansu Province, China. Examinations of the specimen were accomplished using a Leica S8APO stereomicroscope, equipped with a Leica DFC295 camera. Images were digitally stacked as photomicrographic composites of approximately 20 individual focal planes obtained using the software Helicon Focus 6 for better visualisation of the 3D structures. Drawings for the analysis were based on the specimen and photographs. Figures were prepared with CorelDraw X4 and Adobe Photoshop CS6.
General terminology of wing venation follows Kukalová-Peck and Lawrence (2004) as interpreted by Yang et al. (2012) and Yang et al. (2014). Terminology of the wing spaces and details of venation (e.g. spaces, veinlets) follows Oswald (1993) and the cross-veins designation follows Makarkin (2015). Terminology of genitalia follows Aspöck and Aspöck (2008). Cross-veins are designated after the longitudinal veins which they connect and are numbered in sequence from the base to the apex of the wing, for example, 1sc-r, first (proximal-most) cross-vein connecting Sc and R; 2micu, second cross-vein between M/MP and Cu/CuA.
The identification key to the Berothidae species from Myanmar amber was modified from that provided by Yuan et al. (2016), based on the characters of the new species.

Order Neuroptera Linnaeus, 1758 Family Berothidae Handlirsch, 1906 Genus Jersiberotha Grimaldi, 2000
Jersiberotha musivum sp. nov. http://zoobank.org/76B6E201-6262-4FC0-ACAC-1FF50C04815C Diagnosis. Jersiberotha musivum may be easily distinguished from the other four species of Jersiberotha by a combination of the following character states: in forewing, two cross-veins ra-rp are present; inner or outer graduate series of cross-veins are absent; RP has three branches; ma-mp cross-veins and cua-cup cross-veins are absent; and basal cross-vein 1r-m is absent from hind wing.
Etymology. The specific name is from the Latin "musivum" (meaning "mosaic"), in reference of the new species with some characters in wing venation occurring mosaically in both two similar genera, i.e. Iceloberotha and Jersiberotha.
Material examined. Holotype LZUGSW20210219; deposited in the Institute of Paleontology and Stratigraphy, School of Earth Sciences, Lanzhou University, Gansu Province, China.
Description. Female (Fig. 1A). Body length ca. 1.50 mm as preserved. Head: oval in lateral view, length ca. 0.2 mm. Compound eyes prominent, ovoid, large, length ca. 0.14 mm. Vertex with sparse long setae. 3 rd and 4 th segments of maxillary palpus relatively short, approximately twice as long as wide; apical tarsomere elongated, very acute distally, approximately five times as long as wide. Labial palpus not fully visible. Antenna: length ca. 0.5 mm (Fig. 1B), scapus elongate, approximately three times as long as maximum width; pedicellus elongate, approximately two times longer than maximum width and slightly broader than flagellomeres; the following 21 flagellomeres, cylindrical, slightly longer than wide, with relatively long setae around; basal flagellomeres transverse, distal flagellomeres slightly elongate; apical flagellomere conical.
Forewing: narrowly slender and oval shaped ( Fig. 2A, B), length ca. 1.70 mm, width ca. 0.55 mm. Leading edge with short setae, trailing edge with long setae. Costal space narrow, slightly narrowed medially. All subcostal veinlets simple, basal and distal subcostal veinlets slightly curved. Humeral veinlet cross-vein-like. Subcostal space nearly as broad as costal space, proximal cross-vein (1scp-r) located proximad at origin of RP; ScP terminating at RA. ScP+RA entering margin before wing apex, shallowly forked distally with five short branches. RA space a little broader than subcostal space, with only two cross-veins present, the basal one proximad to middle of wing and the distal one proximad at fusion of ScP and RA. RA slightly thickened; RP originating from RA relatively distant from wing base, with two long branches originating between 2ra-rp and 3ra-rp and one short branch distad at 3ra-rp. RP1 with 2 branches, primary fork distad at 3ra-rp, one branch not forked, other with three pectinate distal branches; stem of RP, RP2 and RP3 shallowly forked. No crossveins between branches of RP. M fused with R basally. One cross-vein between RP and M (2r-m) connecting stem of RP and MA. M basally approaching R; forked nearly at origin of RP. MA forked primarily distad at 3ra-rp, proximal branch with two pectinate distal branches, distal branch once forked distally; MP forked primarily between 2ra-rp and 3 ra-rp, proximal branch with two pectinate distal branches, distal branch once forked distally. No cross-veins between MA and MP. Two crossveins between M and Cu: 1m-cu connecting M and Cu distad at origin of CuP; 2m-cu connecting MP and CuA. Cu divided into CuA and CuP rather far from wing base. CuA and CuP dichotomously branched. No intracubital cross-veins. One cross-vein (1cu-aa1) between Cu and AA1 connecting CuP, AA1 much proximad to their branching. AA1 once forked distally, AA2 thickened, pectinately branched, with two short branches. AA3 short, simple. Marginal setae long to very long and arranged in bunches at end of veins and trichosors. Trichosors prominent along entire wing margin. Wing membrane hyaline, with following dark brown maculation; narrowly margined cross-vein 2ra-rp, 3ra-rp and 2r-m; widely margined cross-vein 2m-cu; spots at origin (inside) of RP, RP1, RP3 and at primary forks of RP1, MA, MP, CuA and CuP.
Hind wing: narrowed proximally, broadened distally, length ca. 1.40 mm, width ca. 0.55 mm (Fig. 2C, D). Costal space strongly narrowed medially, slightly dilated proximally and strongly dilated distad at fusion of ScP and RA. Subcostal veinlets simple, closely spaced; distal subcostal veinlets strongly oblique, thickened. Subcostal space rather broad, basally appears narrowed; no cross-veins detected. ScP stout, nearly straight before terminating at RA, ScP + RA entering margin far before wing apex, veinlets are difficult to be accurately counted, but it appears there are six veinlets. RA space clearly wider than subcostal space, with one cross-vein proximad to fusion of ScP and RA, none distad. RP originating rather far from wing base, with two branches originated proximad to 3ra-rp, none distad. Stem of RP, RP1 and RP2 shallowly once forked. No cross-veins between branches of RA, RP and M; basal 1r-m absent. M basally fused with R; forked distad origin of RP. MA and MP nearly parallel for most of the length; MA dichotomously branched; MP pectinately branched, with two short simple branches, no intramedian cross-veins. Cross-veins between M, Cu (1m-cu) not discernible. CuA pectinately branched, with three short simple branches. CuP and AA1 not detected. Marginal setae very long, arranged in bunches at end of veins, especially along hind margin. Wing membrane hyaline, without maculation.
Abdomen oval, stout. All segments clearly visible except terminal-most, with broad membranous space between sternites and tergites (Fig. 3A). Tergite I not visible, Tergite II and sternite II shorter than tergites and sternites of abdominal segments III -VII, without specialised modifications. Tergite VIII well developed, dorsally broader than laterally, elongate and extending towards the sternite. Tergite IX not clearly identified, sternite VIII reduced. The genitalia structures of the new species are not well preserved, the pair of ectoprocts (e) are slightly shorter than the other pair of gonocoxites (gcx) and the unpaired club-shape process may be a part of inner genitalia (Fig. 3B, C). All tergites and sternites covered with dense, long fine setae.  The new species Jersiberotha musivum sp. nov. can be assigned to the family Berothidae, based on the forked veins in subcostal region and the scape three times as long as wide.
A new identification key to the species of Berothidae from Myanmar amber has been presented and compared with the new species of other ones of this family. The venation of Jersiberotha musivum sp. nov. differs from that of Protoberotha Huang, 2018 andEthiroberotha Engel &Grimaldi, 2008 in presence of cross-veins ra-rp in forewing, which is absent in both above-mentioned genera. The new species has more than one ra-rp cross-veins in forewing, differentiating it from the representatives of Haploberotha Engel & Grimaldi, 2008, which only has one ra-rp cross-vein. The species of Maculaberotha Yuan, 2016 has RP with four branches in forewing and more than 70 flagellomeres, while the J. musivum sp. nov. possesses RP with three branches and flagellum with 21 flagellomeres. The distalmost ra-rp cross-vein before ScP-RA fusion in forewing differs that of Telistoberotha Grimaldi, 2008 andDasyberotha Engel &Grimaldi, 2008, which have the cross-vein ra-rp beyond ScP-RA fusion.
Jersiberotha musivum sp. nov. also differs from that of Systenoberotha Engel & Grimaldi, 2008 in the scape three times as long as wide, in contrast to the scape being as long as wide in Systenoberotha, from Magniberotha Yuan, 2016 in humeral vein simple, not recurrent and RP with three branches in forewing, in contrast to the humeral vein being recurrent and RP with five branches in Magniberotha, as well as from that of Ansoberotha Yang, 2019, Cornoberotha Yang, 2020and Dolichoberotha Yang, 2020 in flagellum with 21 flagellomeres, in contrast to the flagellum having more than 70 flagellomeres in all the three above-mentioned genera.
Amongst all known members of Berothidae, the venation of Jersiberotha musivum sp. nov. is more similar to that of Iceloberotha Engel & Grimaldi, 2008. Jersiberotha and Iceloberotha were initially distinguished, based on the obviously diagnostic characters of venation, i.e. speckless forewing in Iceloberotha vs. distinctly spotted forewing in Jersiberotha; absence of cross-vein ma-mp and cua-cup in Iceloberotha vs. presence of ma-mp and cua-cup in Jersiberotha (referring to the key to genera in Engel and Grimaldi 2008). Actually, these characters occurred mosaically in both genera, for example, the Myanmar species J. tauberorum Engel & Grimaldi, 2008 clearly loses the cross-veins ma-mp and cua-cup, while the type species of Iceloberotha has an evident ma-mp cross-vein in the original drawings (Engel and Grimaldi 2008). The new species can be assigned to Jersiberotha, based on flagellum with 21 flagellomeres, forewing with distinct areas of infuscation surrounding cross-veins and vein forks, all cross-veins simple prior to ScP-RA fusion, presence of two cross-veins ra-rp, absence of inner or outer graduate series of cross-veins; RP with three branches.
The venation of the new species clearly differs from that of Iceloberotha Engel & Grimaldi, 2008 in forewing with distinct areas of infuscation surrounding cross-veins and vein forks, but the representatives of Iceloberotha lack areas of infuscation and all c-sc cross-veins are simple prior to ScP-RA fusion. J. musivum sp. nov. also differs from that of J. myanmarensis Engel & Grimaldi, 2008 and two New Jersey species (J. luzzii Grimaldi, 2000 andJ. similis Grimaldi, 2000) in forewing with ma-mp cross-vein and cua-cup cross-vein absent, with the forewing with ma-mp cross-vein and cua-cup crossvein being present in all three above-mentioned genera, as well as from J. tauberorum that has a 1r-m cross-vein on hind wing and cross-vein absent in the new species. Additionally, the absence of outer gradate series of cross-veins in the new species is similar to that of I. simulatrix Grimaldi, 2008 andJ. tauberorum Engel &Grimaldi, 2008. The loss of the gradate series is not found in extant berothids (Makarkin 2018).
In summary, the above analysis indicates the fossil specimen here is most closely related to the genus Jersiberotha due to the observed combination of character states. The previous diagnoses of Jersiberotha and Iceloberotha are quite unclear because some characters occur mosaically in both genera. The diagnosis of Jersiberotha should be revised as flagellum with 21-22 flagellomeres, forewing with distinct areas of infuscation surrounding cross-veins and vein forks, some or all cross-veins simple prior to ScP-RA fusion, presence of more than one cross-veins ra-rp, absence of inner or outer graduate series of crossveins; RP with no more than three branches and the diagnosis of Iceloberotha should be revised as flagellum with 21-22 flagellomeres, forewing without distinct areas of infuscation surrounding cross-veins and vein forks, all cross-veins simple prior to ScP-RA fusion, presence of more than one cross-veins ra-rp, RP with no more than three branches.

Conclusions
Jersiberotha musivum sp. nov. was described, based on a single, female from mid-Cretaceous Myanmar amber. The previous diagnosis between Iceloberotha and Jersiberotha was quite indistinct because some characters occurred mosaically in both genera. A new identification key to the Berothidae species from Myanmar amber was provided to distinguish the new species from others in the Berothidae and the revised diagnoses of Iceloberotha and Jersiberotha were also updated.
Makarkin, Dr. David Bowles and Dr. Caleb Califre Martins) and another anonymous