Research Article |
Corresponding author: Viktor Baranov ( baranowiktor@gmail.com ) Academic editor: Alexander Schmidt
© 2022 Viktor Baranov, Ricardo Pérez-de la Fuente, Michael S. Engel, Jörg U. Hammel, Christine Kiesmüller, Marie K. Hörnig, Paula G. Pazinato, Corleone Stahlecker, Carolin Haug, Joachim T. Haug.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Baranov V, Pérez-de la Fuente R, Engel MS, Hammel JU, Kiesmüller C, Hörnig MK, Pazinato PG, Stahlecker C, Haug C, Haug JT (2022) The first adult mantis lacewing from Baltic amber, with an evaluation of the post-Cretaceous loss of morphological diversity of raptorial appendages in Mantispidae. Fossil Record 25(1): 11-24. https://doi.org/10.3897/fr.25.80134
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Mantis lacewings (Neuroptera: Mantispidae) are prominent and charismatic predatory representatives of Insecta. Nevertheless, representatives of the group are surprisingly scarce in Paleogene deposits after a relative abundance of specimens known from Cretaceous. Here we present Mantispa? damzenogedanica sp. nov., representing the first adult of Mantispidae described from Baltic amber and the only Eocene adult mantispid hitherto preserved in amber. The new fossil species is also among the earliest representatives of Mantispinae, certainly the oldest adult of this group described from amber. Additionally, we discuss the changes through time in the ecological morphospace within Mantispidae based on the morphological diversity (≈disparity) of the raptorial legs. Possible explanations for the post-Cretaceous decline in the morphological diversity of mantis lacewings are posited.
amber, fossil, lacewings, mantid flies, morphology, Neuroptera, shape
Many of the numerous representatives of Insecta unfortunately invoke revulsion in most people. Nonetheless, some groups can inspire greater collective fascination and even appreciation and affection, such as butterflies and bees. Alongside these are the praying mantises (Mantodea), which are often kept and bred as pets as well as featured in zoological displays and educational programs (
Mantis lacewings are representatives of Neuroptera (i.e., lacewings and their relatives). Neuroptera today comprise about 6,000 species worldwide (
Although diverse by neuropteran standards, mantis lacewings lack the remarkable diversity of other holometabolans, such as beetles, wasps, and flies. The group Neuroptera, and in fact the more inclusive group Neuropterida, which includes the species-poor lineages Megaloptera and Raphidioptera, is likely to have been significantly more diversified and disparate in the Cretaceous (e.g.,
Mantis lacewings seem to have been more dominant, or at least common, in the Cretaceous, as demonstrated by numerous adult mantis lacewings in Cretaceous deposits, especially in amber (
The Eocene record of Mantispidae is rather sparse and hampers a further understanding of the evolution of the group. A single adult specimen from British amber, Whalfera venatrix
Here we report the first adult of Mantispidae from Baltic amber and place it into a larger framework regarding the quantitative morphology of raptorial forelegs across the lineage in terms of extant and extinct diversity. These morphometric comparisons serve as a proxy for the breadth of ecologies and predatory behaviors within Mantispidae during different episodes of their evolutionary history.
The specimen studied herein corresponds to an adult mantis lacewing preserved in Eocene Baltic amber. The specimen was found at the Yantarny mine, Kaliningrad (Russia), and originally belonged to the personal collection of Jonas Damzen, who acquired it from a commercial source in Yantarny, Kaliningrad District. The specimen is now deposited in the Museum of Gdańsk (Gdańsk, Poland), under the accession number MG/B/1172. The sediments bearing the Baltic amber have sometimes been stratigraphically placed as late Bartonian to earliest Priabonian, with the richer concentrations of amber lower among these, based on lithological and palynological data (
The specimen was documented using microscopy and synchrotron radiation-based X-ray computed microtomography (SR-µCT). First, the specimen was examined under a Keyence VHX-6000 digital microscope under different light settings (
The amber specimen was scanned with Imaging Beamline P05 (IBL; Greving et al. 2014, Wilde et al. 2016) operated by the Helmholtz-Zentrum Hereon at the PETRA III storage ring (Deutsches Elektronen Synchrotron – DESY, Hamburg, Germany), using a photon energy of 18 keV and a sample-to-detector distance of 100 mm. Projections were recorded with a custom developed 20 MP CMOS camera system with an effective pixel size of 1.28 µm (
In order to provide a comparative framework, we considered all fossil representatives of the group Mantispidae from the literature in which the profemur and its inner integumentary processes bearing terminal modified setae (i.e., the often so-called ‘spines’), including the largest of such processes if present (the so-called major ‘spine’), were accessible. Therefore, a total 22 fossil specimens, plus the new species, were included (see Suppl. material
The program package Shape was used for further analysis (
Wing venation interpretation and nomenclature follows that of
Neuroptera Linnaeus, 1758
Mantispidae Leach, 1815
Mantispinae Leach, 1815
Mantispa Illiger in Kugelann, 1798
The specific epithet is a combination of ‘Damzen’, honouring Mr. Jonas Damzen (Vilnius), who found, prepared, and made the specimen available, and ‘gedanicum’, relative to Gedania, one of the Latin names for Gdańsk (Poland), where the specimen will be housed permanently.
MG/B/1172, Museum of Gdańsk (Gdańsk, Poland). The specimen is well preserved, albeit missing distal parts of some appendages and heavily covered by white foam (= ‘Verlumung’), particularly thick on the posterior part of the body, namely the abdomen. A single spider and six non-biting midges (Diptera: Chironomidae: Chironominae: Tanytarsini) are present as syninclusions.
Baltic amber from Yantarny mine in Yantarny, Kaliningrad (formerly Palmnicken, Königsberg), Russia; Eocene (late Bartonian‒earliest Priabonian). The precise extraction location within the Yantarny mine remains unknown.
In accordance with the ICZN, the specific epithet is registered in ZooBank (www.zoobank.org) under the following LSID: 8C79CEEC-9800-4EB3-9665-B6FE756F83FF.
The new specimen can be distinguished from all extant and fossil mantis lacewing representatives based on the following combination of characters: Head moderately wider than long; antennae relatively short, with flagellomeres compact and slightly wider than long in profile, last flagellomere gradually tapering distally; distal third of antennae seemingly with a pale band; occiput, pronotum and mesothorax bearing short, stout, erect setae, at least those from the occiput and pronotum not confined to raised bases; pronotum about 4.6× times longer than wide posteriorly, lacking abrupt constrictions throughout, apparently smooth; forewing with pterostigma well sclerotized, elongate, bearing sparse macrosetae along its entire length, distally ending at the midlength of cell 3r, proximal end tapered; forewing lacking supernumerary radial crossveins, with cell 4r small, proximally closed by a brief 3ra-rp crossvein; profemur with major integumentary process (‘spine’) smooth, length 0.52× the profemoral length, with ten smaller processes.
Sex unknown. Winged lacewing, total length 13.7 mm as preserved. Head. Broad, short, moderately wider than long, 1.5 mm wide, 0.9 mm long, roughly triangular in anterior view. Ocular segment recognizable by large, ovoid compound eyes, 0.97 mm in diameter, prominent yet not particularly abutting, and trapezoid labrum, about 0.30 mm long. Posterior region of head capsule (occiput) with short, stout, erect setae visible through Verlumung, apparently not confined to raised bases. Antenna long (about 1.9 mm), with at least 22 articles (scapus, pedicellus, flagellomeres); distal third of antennae seemingly with a pale band. Flagellomeres rectangular in profile, slightly wider than long, compact, not significantly expanding in width distally. Mandibles 0.32 mm long. No further details accessible. Maxillae elongate, with proximal part, stipes (with two endites, galea and stipes), and distal part, palp, visible. Lacinia elongate, with eight strong distal teeth, 0.40 mm long. Galea about 0.14 mm long. Maxillary palp arising latero-distally from stipes, cylindrical, with three visible palpomeres. Total length of the palpomeres 0.50 mm long.
Mantispa? damzenogedanica sp. nov., holotype MG/B/1172. A. Photograph of the habitus in lateral view; A1. Mesothorax with stout setae visible through the Verlumung, enlarged (arrows); B. Drawing of the right forewing. Abbreviations (mostly veins): 1‒4r = radial cells; A = anal; CuA = cubitus anterior; CuP = cubitus posterior; C = costa; MA, media anterior; MP, media posterior; pt = pterostigma; RA = radius anterior; RP = radius posterior; Sc = subcosta.
Labium oval in general shape. Details challenging to discern due to partial concealing by structures of thorax.
Thorax. Prothorax elongate, with pronotum tubular (fully fused ventrally), cylindrical, slightly decreasing in diameter distally, then expanding from its distal 2/3 onwards, 3× longer than wide (maximum width), 3.2 mm long, 1.1 mm wide basally, 0.6 mm wide medially, 0.8 mm wide distally. Prothorax densely covered with microtrochia, with smooth dorsal surface. Maculae (i.e., paired anteriodorsal areas of the pronotum distinctive in colour and/or shape, if apparent) with inconspicuous acute cusps. Pronotum very elongate, about 4.6× longer than wide posteriorly, lacking transversal ridges or corrugations (exact texture unknown due to Verlumung covering); pronotal prozone gently raised in lateral view, anterior edge with two lateral rounded invaginations and a median, rather acute protrusion in dorsal view. Pronotum with short, stout, erect setae visible through Verlumung, not confined to raised bases. Prothorax bearing a pair of prominent appendages in far anterior position, i.e., the raptorial forelegs (only one preserved more completely). Coxa 3.40 mm long; trochanter, ca. 0.60 mm long; femur prominent, 3.30 mm long; tibia 2.48 mm long; tarsus 0.25 mm long; pretarsus not visible. Femur compressed, with prominent integumentary processes (‘spines’) originating medially; most prominent ‘spine’ submedial in position, located at 0.85 mm from proximal edge; at least ten additional, less-developed ‘spines’ present; exact armature hard to discern due to Verlumung. Stitz organs (terminal, sensory chitinous cones on integumentary processes) not discernible. Combined length of tibia and tarsus much shorter than that of femur. Tarsus composed of five tarsomeres. Tarsomere 1 not distally extended, longer than remaining tarsomeres. Pretarsal claw not visible; possible arolium not discernible.
Mantispa? damzenogedanica sp. nov., holotype MG/B/1172, all volume renderings based on SRµCT. A. Habitus in lateral view; B. Head and thorax in dorsal view; C. Head and anterior pronotum in lateral view; D. Left raptorial foreleg in lateral view; E. Detail of the former. Abbreviations: an = antenna; cx = coxa; fe = femur; pt = prothorax; pt1‒5 = tarsomeres 1‒5; ta = protarsus; sb = submedial ‘spine’.
Mesothorax trapezoid in dorsal view, 0.80 mm long. Dorsal surface with several setae visible through Verlumung. Femur 2.20 mm long; tibia 1.70 mm long; basitarsus 2.20 mm long; pretarsal claws simple.
Mantispa? damzenogedanica sp. nov., holotype MG/B/1172. A. Photograph of the head and anterior pronotum in lateral view; B. Same, tagged and colour-marked; C. Head in ventral view, volume rendering based on SRµCT, showing visible mouthparts; D. Detail of the anterior pronotum in lateral view; note the stout setae (arrows). Abbreviations: an = antenna; ey = eyes; lb = labrum; md = mandible; mp = maxillary palp; mx = maxilla, proximal part; pt = prothorax.
Forewing 9.9 mm long, 2.7 mm wide, relatively narrow in shape; membrane apparently hyaline, with no visible infuscations (i.e., darkened areas) other than that of the pterostigma. Venation dark in colour; trichosors (i.e., veinlet-like structures between proper wing veins present at the wing margin, often highly setose) absent along all costal margin; all veins sparsely setose, with R bearing particularly long setae; humeral vein not visible; five costal veinlets present; Sc apparently meeting C half the length of 1rp cell; no sc-r or sc-ra crossveins visible, if present; pterostigma well-sclerotised, apparently tapered basally, gently expanding distally, bearing sparse setae, beginning distally of 1ra-rp crossvein, ending midway of cell 3r; distal edge of pterostigma sub-perpendicular to costal margin (not markedly oblique/subparallel); space between C and RA relatively broad throughout; radial triangle distinct, relatively small; four radial cells (1r‒4r) between RA and main branch of RP, the distalmost (4r) distinctly small, subtrapezoid, closed proximally by a very brief 3ra-rp crossvein; RP with five posterior branches; media simple, reaching wing margin right below cell 1r; CuA and CuP simple, forking not visible (blocked by a bubble), but likely proximal to radial triangle; cup-a1 crossvein not visible (blocked by a bubble); all anal veins simple, A1 concave; A2 sinuous, A3 slightly convex, these two fused proximally with a thick common stem; a1-a2 crossvein not visible.
Metathorax difficult to observe both on optical and 3d images. Femur 1.80 mm long; tibia 2.30 mm long; basitarsus 3.50 mm long, further distal tarsomeres not preserved. Hind wings almost entirely covered by the forewings and hence venation not discernible.
Abdomen. Abdomen largely concealed by Verlumung. Individual segments not discernible. Tergites appear simple, not keeled. Genitalia not visible.
The final data set included three species of Mantispidae from the Jurassic, 14 from the Cretaceous, two from the Eocene, three from the Miocene, and 38 extant specimens. These encompass a wide diversity of the group, including representatives from all major ingroups (‘subfamilies’), both extinct and extant. The shape analysis resulted in five effective principal components (PCs). For the graphical representation of the PC’s correspondence to morphology, see Suppl. material
PC1 explains 43.08% of the overall variation. It is dominated by overall stoutness of the profemur and the size of the major, sub-medial integumentary process (=‘spine’), if present. A low value indicates an overall stout shape and a poorly developed major ‘spine’. A high value indicates a more elongate shape and a well-differentiated major ‘spine’.
PC2 explains 27.84% of the overall variation. It is dominated by overall stoutness of the profemur and the size of the major ‘spine’, if present. A low value indicates that this structure is more differentiated and elongate in shape, whereas a high value indicates that it is less developed, has a stouter shape, and the major ‘spine’ is less well set off.
PC3 explains 11.15% of the overall variation. It is dominated by the position of the major ‘spine’ (if present) along the proximal distal axis. A low value indicates a more distal position, whereas a high value indicates a more proximal position.
PC4 explains 5.22% of the overall variation. It is dominated by the shape of the proximal part of the profemur. A low value indicates a more pointed shape, while a high value indicates a more rounded shape.
PC5 explains 3.78% of the overall variation. It is dominated by the differentiation of the ‘spines’. A low value indicates fewer, well set off ‘spines’, while a high value indicates a greater proportion of not-so-well set off ‘spines’.
Inclusion in amber is an exceptional form of preservation. Nonetheless, while some specimens appear almost life-like and provide access to the finest of details, certain phylogenetically informative structures can be obscured. Different kinds of x-ray microtomography have significantly improved this circumstance, revealing structures of interest, which are often concealed by different elements such as other body structures, air bubbles, debris, or even Verlumung. Still, this method also has its limitations, and it can only resolve structures that are sufficiently well preserved and/or have enough contrast relative to other materials, particularly the surrounding matrix. This is also the case in the new specimen.
The specimen clearly is a representative of the group Mantispinae owing to, among other characters, the concave head vertex in frontal view (not domed); the forewing lacking trichosors, with 2A and 3A veins fused proximally with a thick common stem and a reduced jugal lobe; the mesonotal lobes angled anteriorly (rather than gently and broadly rounded); the procoxae lacking a transverse sulcus; the probasitarsus elongate, longer than remaining protarsomeres; the combined length of protibia and protarsus much shorter than that of the profemur; and the presence of simple, unbranched mesopretarsal claws (
Mantispa? damzenogedanica sp. nov. represents the first record of an adult mantis lacewing in Baltic amber. The only two previous records of Mantispidae from Baltic amber were first-instar larvae (
The new species is among the oldest representatives of Mantispinae currently known, certainly the oldest adult of the group described in amber. The previously oldest representative of Mantispinae, Vectispa relicta Cockerell, 1921, is from the Priabonian (upper Eocene) Bembridge marls, UK (
The fact that the present specimen is the first record of an adult mantis lacewing from Baltic amber is remarkable taking into account that the latter is among the most intensively studied ambers worldwide (
Already on a qualitative level, it is quite apparent that a significant loss in morphological diversity within Mantispidae has taken place since the Cretaceous (
Although
Although Whalfera venatrix was originally described as a representative of Mantispidae (
Morphospace occupied by the femora of raptorial legs of extant and fossil adult representatives of Mantispidae. The profemur of the new species has been circled. Total captured variation = 71.6%; 43.8% at PC1 and 27.8% at PC2. Numbers refer to Suppl. material
Mantispa? damzenogedanica sp. nov. represents the sole definitive Eocene adult of Mantispidae preserved in amber. As the species is well circumscribed within modern morphospace, it tends to support the notion that declines in diversity of Mantispidae occurred prior to the Eocene, differing in this respect from what has been inferred to occur in some other neuropteran lineages where comparable quantitative data are available, at least from larvae (e.g.,
The record presented herein illustrates a striking decline in the Mantispidae morphological diversity over the course of the Cretaceous and Cenozoic. This trend illustrates yet another case of the drastic decline of the morphological diversity in an ingroup of Neuroptera (
All data and results are presented in the main text, tables, figures and supplement. (https://github.com/chironomus/Mantispidae-shape-analysis/blob/main/_CLEANED_FOR_EOCENE_Raptorial_Neuropterans.xls).
Conceptualization: VB, RPF, ME, VB, JTH; Methodology:VB, RPF, ME, JTH; Formal analysis and investigation: RPF, ME, JTH, VB Writing – original draft preparation: JVB, ME, RPF, JTH; Writing – review and editing: all authors; Image preparation : JUH, JTH, CH, PGP, CK, MKH, CS, VB, ME, RPF; Analysis: JTH; Funding acquisition: JTH, VB, CH, JUH. Resources: JTH, VB, JUH.
The authors declare that they have no conflict of interest.
We are grateful to Mr. Jonas Damzen (Vilnius, Lithuania) for preparing the specimen and bringing it to our attention. We extend our gratitude to the editor and the reviewers, Michael Ohl and Louwtjie Snyman, for their insightful comments and edits. This project is supported by the Volkswagen Foundation in the frame of a Lichtenberg Professorship (J.T.H.). This study is also a contribution to the AEI/FEDER, UE project CRE CGL2017-84419 (R.P.-d.l.F.). V.B. was supported by the LMU Excellence Initiative via a LMU Junior Researcher Fund. R.P.-d.l.F. is funded by a Museum Research Fellowship from the Oxford University Museum of Natural History, UK. CK is currently funded by the Landesgraduiertenförderung MV. P.G.P. is funded by CAPES (Process 88887.161379/2017–00). Scanning of the specimen was supported by the DESY Block Allocation Group project “Scanning the past – Reconstructing the diversity in million years old fossil amber specimens using SRµCT” at PETRA III.
Graphical representation of the PC's correspondence to morpholog
Data type: figures
Explanation note: Figure S1. Shape-drivers of the principal components in the PCA analysis. Figure S2. Numbered specimens used in the analysis. Legend to the numbers in the Suppl. material 2: Table S1 (https://github.com/chironomus/Mantispidae-shape-analysis/blob/main/_CLEANED_FOR_EOCENE_Raptorial_Neuropterans.xls).
Table S1. Cleaned for eocene Raptorial Neuropterans
Data type: table