Hoplitolyda duolunica gen. et sp. nov. (Insecta, Hymenoptera, Praesiricidae), the Hitherto Largest Sawfly from the Mesozoic of China
the Hitherto Largest Sawfly from
the Mesozoic of China. PLoS ONE 8(5): e62420. doi:10.1371/journal.pone.0062420
Hoplitolyda duolunica gen. et sp. nov. (Insecta, Hymenoptera, Praesiricidae), the Hitherto Largest Sawfly from the Mesozoic of China
Taiping Gao 0 1
Chungkun Shih 0 1
Alexandr P. Rasnitsyn 0 1
Dong Ren 0 1
Vincent Laudet, Ecole Normale Superieure de Lyon, France
0 1 College of Life Sciences, Capital Normal University , Beijing , China , 2 Paleontological Institute, Russian Academy of Sciences , Moscow , Russia , 3 Department of Palaeontology , Natural History Museum, London, England
1 Hoplitolyda duolunica sp. nov. (Figs. 1, 2, 3) urn:lsid:zoobank.org:act:68E7A450-6F4E-44B9-B2E6- 0CBB0182A8E5 Holotype. No. CNU-HYM-ND-2011016 , a well-preserved sawfly in ventral view, missing the terminal part of the abdomen. The specimen is deposited in the Key Laboratory of Insect Evolution & Enviromental Changes, College of Life Sciences, Capital Normal University , Beijing, China. Description. Very large hymenopteron with a wing span .92.0 mm and body length as preserved about 46.0 mm (Figs. 1A
Background: Large body size of an insect, in general, enhances its capability of predation, competition, and defense, resulting in better survivability and reproduction. Hymenopterans, most being phytophagous or parasitic, have a relatively small to medium body size, typically under 50.0 mm in body length. Principal Findings: Herein, we describe Hoplitolyda duolunica gen. et sp. nov., assigned to Praesiricidae, from the Early Cretaceous Yixian Formation of China. This new species is the largest fossil hymenopteran hitherto with body estimated .55.0 mm long and wing span .92.0 mm. H. duolunica is, to our knowledge, the only sawfly with Sc present in the hind wing but not in the forewing. Its Rs1 and M1 meeting each other at 145u angle represents an intermediate in the transition from ''Y'' to ''T'' shapes. Even though Hoplitolyda differs significantly from all previously described genera in two subfamilies of Praesricidae, we leave the new genus unplaced in existing subfamilies, pending discovery of material with more taxonomic structure. Conclusions/Significance: Hoplitolyda has many unique and interesting characters which might have benefitted its competition, survival, and reproduction: large body size and head with robust and strong mandibles for defense and/or sexual selection, unique wing venation and setal arrangements for flight capability and mobility, dense hairs on body and legs for sensing and protection, etc. Considering the reported ferocious predators of feathered dinosaurs, pterosaurs, birds, and mammals coexisting in the same eco-system, Hoplitolyda is an interesting case of ''survival of the fittest'' in facing its evolutionary challenges.
Funding: This research is supported by the National Basic Research Program of China (973 Program) (grant 2012CB821906), the National Natural Science
Foundation of China (grants 31230065, 31272352, 41272006), Project of Great Wall Scholar and KEY project of Beijing Municipal Commission of Education Project
(grants KZ201310028033), China Geological Survey (grant 1212011120115) to DR, and the Presidium RAS Program Origin and evolution of the geo-biological
system, to RAS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
Praesricidae is a small extinct sawfly family with four genera and
six species described so far, all these species distributed in Central
Asia. There are currently two subfamilies in the Praesiricidae:
Praesiricinae Rasnitsyn, 1968 comprising Praesirex Rasnitsyn, 1968
and Turgidontes Rasnitsyn, 1990; and Rudisiriciinae Gao,
Rasnitsyn, Ren & Shih, 2010 comprising Aulidontes Rasnitsyn, 1983 and
Rudisiricius Gao, Rasnitsyn, Ren & Shih, 2010. Among them, only
Aulidontes Rasnitysn, 1983 was reported from the Late Jurassic,
while others were found from the Early Cretaceous .
Xyelodontes Rasnitsyn, 1983 was described in Praesiricidae as well,
but currently it is transferred to Xyelydidae, which will be
published in another paper.
Herein we report Hoplitolyda duolunica gen. et sp. nov., which was
collected from Yixian Formation of Nanyingpan Village, the
Sandaogou Township, Duolun County, Inner Mongolia, China.
The age of this insect fauna is about 126 My, belonging to the
famous Jehol biota [5,6]. The fossil matrices are dark gray with
darker insect imprints under low-angle lighting. The insect fauna
found at this locality comprises many ephemeropteran nymphs of
various stages, a lot of coptoclavids (Coleoptera), some
mecopterans, trichopterans and dipterans, a few hymenopterans and a
flealike insect fossil, Pseudopulex magnus Gao, Shih & Ren, 2012,
recently reported .
Records of giant hymenopterons are sparse. Shih et al.
described a pelecinid, Megapelecinus changi Shih, Liu & Ren, 2010,
with a body length of 50.9 mm from the Early Cretaceous of the
Yixian Formation, Liaoning, China . Archibald et al. reported a
formicid, Titanomyrma lubei Archibald, Johnson, Mathewes &
Greenwood, 2011, with a body length of approximately
51.0 mm from the latest Early Eocene of the Green River
Formation, Wyoming, USA . Hoplitolyda duolunica gen. et sp.
nov. is the largest fossil hymenopteran hitherto with a very large
body (estimated .55.0 mm long) and a broad wing span
Materials and Methods
We sorted two thousand hymenopteran fossils from Yixian
Formation of China, but we only found one such sawfly. The
specimen is housed in the Key Laboratory of Insect Evolution &
Environmental Changes, College of Life Sciences, Capital Normal
University, Beijing, China. No specific permits were required for
the described field studies.
The specimen was examined under a Leica MZ 16.5 dissecting
microscope (Leica, Wetzlar, Germany). Line drawings were
prepared with CorelDraw X6 graphics (Version 220.127.116.117) (Corel
Corporation. USA) and Adobe Photoshop CS 6.0 (Version 13.0.1)
(Adobe Systems Incorporated, USA) software. The photographs
and magnified images of parts of the specimen were taken with a
camera system connecting with the Leica MZ 16.5. Sometimes, we
dropped ethanol (95%) on the surface of the specimen for much
clearer photos. The wing venation nomenclature used in this
paper is based on the interpretation of Huber and Sharkey, 1993
Venation abbreviations used in the text and figures: C, Costal;
Sc, Subcostal; R, Radial; Cu, Cubital; A, Anal; Rs, Radial sector;
Locality and Horizon
Nanyingpan Village is located in Sandaogou Township, Duolun
County, Inner Mongolia, China. The age of the fossil-bearing beds
in the Nanyingpan Village area is considered to be Early
Cretaceous, Yixian Formation, around 126 Ma .
The electronic edition of this article conforms to the
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ICZN. The Zoobank LSIDs (Life Science Identifiers) can be
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Hoplitolyda gen. nov
Type species. Hoplitolyda duolunica sp. nov.
Diagnosis. Large hymenopteron with head subcircular,
widest at mandibular base. Mandible sickle-shaped, with single
preapical tooth. Antenna with scape moderately long and 3rd
antennomere not disproportionally enlarged. Fore leg apparently
resting on substrate with tibial apex and base of basitarsus flexed
below tibia, with foretibial apical spur apparently lost. Forewing
with Sc absent, R and pterostigma narrow, Rs1 reclined, meeting
M1 at about 145u, RS+M very short, cells 1Rs and 1 M very long.
Hind wing with Sc present.
Remarks. Hoplitolyda is assigned to Praesiricidae based on the
combination of lost Sc in forewing, straight R, and trapezoidal
mesopseudosternum widely reaching fore margin of
mesoventropleuron (synapomorphies with Megalodontesidae, a living family
known since the Early Cretaceous, from Jibaissodes Ren, Lu, Guo
& Ji, 1995 [14,15]) with bent M+Cu and simple flagellum. Unlike
Praesiricidae, Megalodontesidae are apomorphic in having
straight M+Cu and flagellum pectinate or flabellate. Its position
in Pamphilioidea is confirmed: besides the general similarity in
wing venation and in having long two-toothed mandibles, by the
specific structure of the clypeus connected ventrally with the
hypostomes and so with the mandibular and oral cavities
separated. Hoplitolyda differs from other genera of Praesiricidae
in its huge size, homonomous flagellum, head widest at
mandibular base, forewing with comparatively thin R, narrow
pterostigma, very long cells Rs and 1 M, hind wing Sc present,
and in long pubescence on head and thorax. Some characters are
possibly unique in all Symphyta, particularly the postocciput with
transverse fore margin and narrow postoccipital bridge. Some
others might be unique in all Hymenoptera: fore tarsus flexed far
under tibia and with basitarsus much elongate, and M+Cu with a
stub directed forward. That stub is symmetrical in both wings and
so it looks like a normal character of the taxon. However, it is an
unusual structure, a novelty that has no known homologue, and so
also looks like an individual aberration. Only future finds might
resolve this puzzle. One more possibly unique feature of the new
genus is the putative absence of the antennal preening device
including a modified hind (outer) apical spur and facing it an
excision of the basitarsus. The only other member of Symphyta
known to lack the apical foretibial spur is Pachylota Westwood,
1841 (Argidae) which has all the tibiae lacking apical spurs, unlike
the present fossil.
As aforementioned, there are currently two subfamilies with
four described genera. We add this fifth genus which differs much
from all four other genera. Hoplitolyda could be easily segregated as
a subfamily of its own. However, it is strange and excessive to have
three subfamilies just for five genera. It might be wiser to leave the
genus unplaced for now in the hope of getting more material that
would make it possible to consider the taxonomic structure of the
family in more detail.
Etymology. The name combines the Greek "Hoplit-"
referring to "fully armed" and Lyda Fabricius, 1804, a junior synonym
of Pamphilius Latreille, 1802 widely used to coin generic names in
Pamphilioidea. Gender feminine.
Figure 1. Hoplitolyda duolunica gen. et sp. nov., from the Early Cretaceous of China. A and B, photograph and line drawing; C, bristles on
basitarsus of middle leg; D, spurs on hind leg; E, hairs below the vein C of forewing; F, hamuli on hind wing; G, hairs on tibia of fore leg; H, mandibles;
I, hairs on abdomen. Scale Bars for A and B: 10.0 mm, for C to I: 0.5 mm.
B). Missing abdominal segments 6 to 8 estimated with average
length ,3.5 mm each (by comparing ratios of abdominal
segments to body length for species of Rudisiricius ), thus full
body length estimated .55.0 mm. Body and legs covered with
dense hairs. Surface sculpture not apparent. Color pattern not
precisely known, head and thorax probably dark, abdominal
segments (terga?) pale with dark median and posterolateral spots.
Head (Figs 1H, 2A, B) massive, width 15.4 mm, length without
mandibles 9.3 mm, eyes unknown (evidently placed on invisible
dorsal surface). Antenna somewhat longer than head width, with
27 visible antennomeres; scape more than twice as long as wide
(incompletely preserved), possibly as long as 45 basal
flagellomeres combined; pedicel very short; flagellomeres growing shorter
and narrower toward apex, subquadrate or, subapical ones,
elongate. Mandible (about 15.8 mm in length) long and sharp,
reaching opposite side of head when closed, with long apical tooth
and short, curved subapical one placed just beyond mandible
midlength. Clypeus with wide semicircular lower rim joining lower
head surface (apparently postocciput, but morphologically must be
hypostome) laterally. Dorsal head surface not preserved, ventral
one with complete occipital carina meeting hypostomal carina at
mandibular base, with hypostome not distinctly visible: either not
preserved or, rather, bent vertically, hypostomal carinae (visible
only as fore margin of postocciput) directed strictly transversely, so
forming almost straight line. Postocciput wide, delimited by
semicircular occipital carina posteriorly and laterally, forming
narrow postoccipital bridge with mesal boundary lost or not
preserved. Maxilla not preserved; labium small, preserved as two
apical lobes and three-segmented palp with two basal segments
subequal and apical longest.
Forewing (Figs 3A, B) 41.6 mm long, 11.5 mm wide, with
delicate hairs anteriorly in costal space (Fig. 1E). Pterostigma
narrow (5.4 mm long, 0.8 mm wide basally), fully sclerotized,
wedge shaped. Sc absent. R straight (without distinct bend at base
of Rs nor before it), not thicker than C. Rs1 (1.7 mm) slightly
reclined toward wing base, almost aligned with M1, a little longer
than M1 (1.6 mm), meeting M1 at about 145u. Rs+M (1.9 mm) a
little longer than Rs1 or M1, reaching only 1/4 length of cell 1 M.
Vein 1r-rs (,0.9 mm) 1/3 length of 2r-rs (2.9 mm). Rs3 curved.
M+Cu bent before vein M1, with a stub directed toward wing fore
margin. Vein M lacking free apex. Cu nearly straight within cell
1 M, Cu1 (,3.3 mm) slightly shorter than Cu2 (,3.5 mm), but a
little longer than 1cu-a (,2.2 mm). Crossvein 1cu-a originating
from Cu at midlength of cell 1 M. Cu3 aligned with 2cu-a.
Crossvein 1 m-cu joining vein M at midlength of cell Rs, longer
than M1 and as long as Cu3; 2 m-cu oblique, joining cell 1Rs2 at
about 2/5 of its length. Crossvein 2rs-m well beyond 2r-rs; 3rs-m
near apex of cell 3R1. Anal veins ordinary. Cell 1R1 very short;
cells Rs and 1 M very long. Cell 1 M with fore and hind margins
almost straight. Hind wing (Figs 3A, C) with at least 10 hamuli
near midlength of cell R1 (Fig. 1F); cell R1 widely rounded
apically. Vein Sc well developed. Rs1 slightly longer than M1.
Crossvein 1rs-m distant from bases of both Rs and M, half as long
as 1 M; 3rs-m near apex of cell R1. Crossvein m-cu long, joining
M2 near midlength of cell Rs. Vein M+Cu and 2A nearly straight;
1A curved near midlength. Vein 3A present. Crossvein cu-a before
midlength of M. Cells 1Cu and 1A truncated before midlength of
cell 1 M. Cell 1Rs2 slightly longer than cell 1 M.
Thorax (Fig. 2) slightly wider than head, covered with dense
hairs of varying length. Propleura long, about 1/2 width of head,
but nearly same height, left and right part of propleuron displaying
a 55u angle (Fig. 2B). Prosternum narrow diamond-like shaped,
half inserted between propleura. Mesoventropleuron short;
mesopseudosternum wide trapezoidal in form, wide on its fore
margin. Pseudosternal sulci ca. 45u to fore and hind margins of
ventropleuron (Fig. 2A).
Coxae and femora short. Fore leg (Fig. 2) with femur narrow,
curved, only slightly thicker than tibia; tibia narrow, covered with
thick hairs (Fig. 1G), no apical spurs preserved; basitarsus long and
narrow (,5.3 mm), shorter than tibia (,7.2 mm), slightly widened
apically, slightly shorter than remaining tarsomeres combined,
with many thick bristles on flexor surface (Fig. 1G) (like at least
mid basitarsus (Fig. 1C) and hind tibia (Fig. 1D)); tarsomere 2 only
slightly elongate, 3 and 4 subquadrate, 5 (poorly preserved) longer
than two preceding combined, with strong claw. Both fore
basitarsi preserved flexed under tibia as if fore leg rests on
substrate on tibial apex and basitarsal base. Mid and hind legs
ordinary; mid and hind trochanters triangular, slightly longer than
wide; femora short, fusiform, hind one thicker. Mid tibia thin, as
long as femur, with apical and preapical spurs rather short; tarsus
much longer than tibia, with basitarsus about as long as remaining
tarsomeres combined, tarsomeres 2 and 3 elongate, 4 ill-preserved,
5 longer than 2, with big claws bearing prominent basal lobe,
otherwise simple. Hind tibia about as long as femur with
trochanter, with apical and preapical spurs short; tarsus not
Abdomen about as wide as head and thorax, with segments 27
partly visible, segments short, covered with dense hairs laterally
Occurrence. Nanyingpan Village, Sandaogou Township,
Duolun County, Inner Mongolia, China. Yixian Formation, Early
Etymology. The specific epithet "duolunica" from "duolun"
referring to the locality of the fossil.
Giant ancient winged insects have been reported from Late
Paleozoic strata, but insect body size decreased in the Mesozoic
and reached the same size as extant ones, possibly due to reduction
of atmospheric oxygen level  and/or the emergence of
efficient insect-eating vertebrates . Other factors affecting
insect body size are environmental temperature, food availability,
isolation (so called island rule), eco-systems, or sexual selection
[20,21]. Large body size of an insect, in general, might enhance its
capability of predation, competition and defense resulting in better
survivability and reproduction, although opposite-directed
pressure is quite common as well. Gigantism of H. duolunica gen. et sp.
nov., as contrasted with other coeval sawflies, might have been
caused by sexual selection or just by niche segregation within their
eco-system to avoid competition.
Male insects, especially of large body size, often have elaborate
and conspicuous ornaments or weapons of exaggerated
proportions . The size and conspicuousness of these structures make
them likely candidates for intraspecific signals, used either by
males to assess the competitive status of rival males, or by females
to assess the relative suitability of potential mates [22,23].
Hoplitolyda duolunica gen. et sp. nov. has a large head with robust
and exaggerated mandibles, a common character of the praesiricid
Rudisiriciinae and the Ferganolyda Rasnitsyn, 1983 males of the
family Xyelydidae . Mandibles of H. duolunica sp. nov., robust
and huge with sufficient support from the big head (Fig. 2B), could
be stretched at a wide angle (Fig. 1H). Thus, these mandibles
might have been used as weapons for defense, the same as many
extant pamphilioids (Family Pamphiliidae). It is interesting to note
that when sexed, all the fossil pamphilioids with exaggerated
robust mandibles are males; it is likely that the huge mandibles
were also used as a sexual display in deterring other rival males
and/or attracting females. On the other hand, the extant
Pamphilioidea (Pamphiliidae and Megalodontesidae) equally have
a big head with long and powerful mandibles but display no real
sexual dimorphism in that respect. Head and mandible
hypertrophy in Hoplitolyda was hardly connected with its feeding habits, for
its weakly developed labium might even indicate aphagy.
Praesiricidae is a small family of Symphyta, now with only seven
described species in five genera. A majority of the species is
confined to the Early Cretaceous (Berriasian through Aptian),
while only Aulidontes mandibulatus Rasnitsyn, 1983 is described from
the Late Jurassic. Despite the narrow age period, the family
displays a wide range of morphological variations in body size,
head, antenna, mandible, leg and wing venation. Size variation is
great, as shown by the most indicative forewing length, ranging
from 8.5 mm in Aulidontes mandibulatus to 41.6 mm in H. duolunica
sp. nov., which is the largest known sawfly. Antennal variation is
shown by scape huge (as long as the head) and basiflagellar
antennomeres disproportionally long (Rudisiricius, Aulidontes), in
contrast to only basiflagellar antennomere much elongate
(Praesirex, Turgidontes) or no antennomere disproportional
(Hoplitolyda). The head can be almost normal (Praesirex, Turgidontes,
Aulidontes) or very large with huge mandibles (Rudisiricius and
particularly Hoplitolyda), even though the head is never as
monstrous as that of Ferganolyda in Xyelydidae (Rasnitsyn et al.,
2006). Legs vary from apparently normal (most genera, even
though their legs are never described in sufficient detail) to
uniquely modified in Hoplitolyda to use the fore-tibial apex along
with the base of the down-flexed basitarsus as a resting point for
the fore leg, while the antennal preening apparatus is apparently
lost. Wing venation varies in these characters: size of pterostigma
(narrow in Hoplitolyda vs. moderately big in all other genera); Rs1
moderately long and proclival (Aulidontes), vertical (Rudisiricius) or
reclival (Hoplitolyda), or else short and reclival (Praesirex) or proclival
(Turgidontes); Rs+M almost as long as cell 1 M (Praesirex, Turgidontes),
half as long (Rudisiricius, Aulidontes), or very short (Hoplitolyda); cell
1 M small (Rudisiricius, Aulidontes), long and high (Praesirex,
Turgidontes), or low but very long (Hoplitolyda); and angle of Rs1
meeting M1 from 93u (Aulidontes) to 180u (Rudisiricius).
An evolutionary trend is revealed by the sections of Rs and M in
the course of formation of the so-called basal vein (red in Fig. 4) as
represented by a series of sawfly fossils. Plesiomorphically, as
shown by most Xyelidae, Rs1 and M1 meet each other at an acute
or right angle (forming a Y shape together with Rs+M), and this
character state is apparently lost in all Pamphilioidea, mainly as a
byproduct of shortening of Rs1 (Fig. 4). The most basal case can
be found in A. mandibulatus (Fig. 4A) , while the other fossils
show a transition (Figs 4BD) [1,25] toward a perfectly linear
alignment of Rs1 and M1 (Figs 4E, F) (forming a T shape
together with Rs+M) , which is the (true) basal vein present in a
majority of Hymenoptera Apocrita [8,26]. The new genus
represents an intermediate position in the transition from Y to
T shapes. The well-developed basal vein is probably important
aerodynamically. In general, wing structures suggest that H.
duolunica sp. nov. was a good flyer, although not an excellent one.
The wing venation of H. duolunica sp. nov. is unique in that it has
no Sc in the forewing in contrast to the hind wing. The most basal
sawflies possessed Sc in both wing pairs in contrast to some derived
taxa and to all higher Hymenoptera which lost Sc completely
[2,27]. As a transition, we can observe forewing Sc retained as a
longitudinal vein, and hind wing lacking any Sc (in majority of
Xyelotomidae and Xyelydidae, in living and some extinct
Siricidae, and in Protosiricidae). However, H. duolunica sp. nov.
is, to our knowledge, the only example when Sc is present in the
hind-and not in the forewing. The new species is also unique in
having a forward stub on its M+Cu, but, as afore-mentioned, more
material is needed to be certain if it is a novelty of evolutionary
meaning, or simply an individual malformation.
In summary, Hoplitolyda gen. nov. has a large body size and
exaggerated mandibles possibly for defense and/or sexual
selection, its unique wing venation and setal arrangements to
enhance flight, dense hairs on body and legs for sensing and
protection. Considering the reported ferocious predators,
feathered dinosaurs, pterosaurs, birds, and mammals ,
coexisting in the same eco-system, Hoplitolyda gen. nov. has demonstrated
an interesting example of survival of the fittest in facing its
We acknowledge Qiang Yang, Mei Wang, Yunzhi Yao and Yongjie Wang
for useful advice and discussions on this article. We express our gratitude to
Prof. Denis Brothers (University of KwaZulu-Natal) and an anonymous
reviewer for their critical review of the manuscript and valuable
Photographs and line drawings: T-PG APR DR. Conceived and designed
the experiments: T-PG C-KS DR. Performed the experiments: T-PG
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