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An enigmatic beetle with affinity to Lamingtoniidae in mid-Cretaceous amber from northern Myanmar (Coleoptera: Cucujoidea)

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An enigmatic cucujiform beetle, Alloterocucus atratus Li, Leschen, Liu, and Cai gen. et sp. nov. , is reported from mid-Cretaceous Burmese amber. The character combination of the new fossil is not completely consistent with any of the known cucujoid or erotyloid families. Based on our phylogenetic analyses, Alloterocucus is assigned to Cucujoidea and may be allied to Lamingtoniidae, which contains a single Australasian genus in the extant fauna. Alloterocucus shares with Lamingtoniidae a similar habitus and a series of characters, including the absence of postocular constriction, 3-segmented antennal club, externally open procoxal cavities, laterally open mesocoxal cavities, exposed pro- and mesotrochantins, and the absence of epipleural fovea and pronotal setose cavities, but differs from extant Lamingtoniidae in its apically truncate terminal maxillary palpomeres, 5-5-4 tarsi in male and absence of distinct dorsal punctation.
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fevo-10-972343 October 29, 2022 Time: 15:29 # 1
TYPE Original Research
PUBLISHED 03 November 2022
DOI 10.3389/fevo.2022.972343
OPEN ACCESS
EDITED BY
Tae-Yoon Park,
Korea Polar Research Institute,
South Korea
REVIEWED BY
Erik Tihelka,
University of Bristol, United Kingdom
Vitalii Igorevich Alekseev,
Immanuel Kant Baltic Federal
University, Russia
*CORRESPONDENCE
Chen-Yang Cai
cycai@nigpas.ac.cn
SPECIALTY SECTION
This article was submitted to
Paleontology,
a section of the journal
Frontiers in Ecology and Evolution
RECEIVED 18 June 2022
ACCEPTED 21 September 2022
PUBLISHED 03 November 2022
CITATION
Li Y-D, Leschen RAB, Liu Z-H,
Huang D-Y and Cai C-Y (2022) An
enigmatic beetle with affinity
to Lamingtoniidae in mid-Cretaceous
amber from northern Myanmar
(Coleoptera: Cucujoidea).
Front. Ecol. Evol. 10:972343.
doi: 10.3389/fevo.2022.972343
COPYRIGHT
© 2022 Li, Leschen, Liu, Huang and
Cai. This is an open-access article
distributed under the terms of the
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(CC BY). The use, distribution or
reproduction in other forums is
permitted, provided the original
author(s) and the copyright owner(s)
are credited and that the original
publication in this journal is cited, in
accordance with accepted academic
practice. No use, distribution or
reproduction is permitted which does
not comply with these terms.
An enigmatic beetle with affinity
to Lamingtoniidae in
mid-Cretaceous amber from
northern Myanmar (Coleoptera:
Cucujoidea)
Yan-Da Li1,2,3, Richard A. B. Leschen4, Zhen-Hua Liu5,
Di-Ying Huang1,2 and Chen-Yang Cai1,2,3*
1State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology
and Palaeontology, Chinese Academy of Sciences, Nanjing, China, 2Center for Excellence in Life
and Paleoenvironment, Nanjing Institute of Geology and Palaeontology, Chinese Academy
of Sciences, Nanjing, China, 3School of Earth Sciences, University of Bristol, Bristol,
United Kingdom, 4Manaaki Whenua Landcare Research, New Zealand Arthropod Collection,
Auckland, New Zealand, 5Guangdong Key Laboratory of Animal Conservation and Resource
Utilization, Guangdong Public Laboratory of Wild Animal Conservation and Utilization, Institute
of Zoology, Guangdong Academy of Sciences, Guangzhou, China
An enigmatic cucujiform beetle, Alloterocucus atratus Li, Leschen, Liu, and
Cai gen. et sp. nov., is reported from mid-Cretaceous Burmese amber. The
character combination of the new fossil is not completely consistent with
any of the known cucujoid or erotyloid families. Based on our phylogenetic
analyses, Alloterocucus is assigned to Cucujoidea and may be allied to
Lamingtoniidae, which contains a single Australasian genus in the extant
fauna. Alloterocucus shares with Lamingtoniidae a similar habitus and a series
of characters, including the absence of postocular constriction, 3-segmented
antennal club, externally open procoxal cavities, laterally open mesocoxal
cavities, exposed pro- and mesotrochantins, and the absence of epipleural
fovea and pronotal setose cavities, but differs from extant Lamingtoniidae in
its apically truncate terminal maxillary palpomeres, 5-5-4 tarsi in male and
absence of distinct dorsal punctation.
Zoobank registration: [https://zoobank.org/], identifier [111CE15E-5B49-
4154-9E4A-7B3A738C6D2A].
KEYWORDS
Cucujoidea, phylogeny, fossil, Burmese amber, Mesozoic
Introduction
The beetle superfamily Cucujoidea of the series Cucujiformia has a complex
taxonomic history. Historically, it is essentially a group of families without clear
diagnostic characteristics of other superfamilies (especially Tenebrionoidea; Crowson,
1955;Lawrence and Newton,1982). The coccinelloid group, once regarded as the
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cerylonid series, was recognized based on multiple lines
of morphological (Crowson,1955;´
Slipi´
nski and Pakaluk,
1991) and molecular evidence (Hunt et al.,2007;Robertson
et al.,2008,2015;Bocak et al.,2014), and formally removed
from Cucujoidea and elevated to its superfamilial status by
Robertson et al. (2015). The phylogenetic relationships within
the remaining Cucujoidea vary dramatically among various
morphological and molecular studies (e.g., Leschen et al.,2005;
Robertson et al.,2008,2015;Lawrence et al.,2011;McElrath
et al.,2015;Timmermans et al.,2016;Zhang et al.,2018;
McKenna et al.,2019). Although some molecular analyses
either based on a few gene markers (Robertson et al.,2015)
or a larger dataset (95 nuclear protein-coding genes) (Zhang
et al.,2018) under a site-homogeneous substitution model
supported a monophyletic Cucujoidea sensu Robertson et al.
(2015), recent studies using transcriptomic data (McKenna
et al.,2019) or a better-fitting site-heterogeneous model (Cai
et al.,2022) have consistently demonstrated the paraphyly
of Cucujoidea sensu Robertson et al. (2015). In light of the
more recent phylogenomic results, Cai et al. (2022) therefore
formally divided Cucujoidea into three superfamilies, namely,
Erotyloidea, Nitiduloidea, and Cucujoidea sensu stricto.
While some families can be characterized based on
distinctive synapomorphies like Cyclaxyridae (Gimmel
et al.,2019), parallelism and convergence of morphological
characters in Cucujoidea sensu lato make it difficult to
assign unusual beetles into an appropriate family, and this
is no truer than amber fossils where the critical assessment
of more subtle characters is required. Moreover, some
of the more critical characters used for distinguishing
Cucujoidea sensu stricto and Erotyloidea are internal genitalic
characters (Cai et al.,2022;Gimmel and Leschen,2022).
For example, Pleuroceratos Poinar and Kirejtshuk from
mid-Cretaceous Burmese amber was originally placed in
Silvanidae, but this placement was later rejected by Liu
et al. (2019) primarily based on its oblique procoxae with
exposed protrochantins. Kirejtshuk et al. (2019) subsequently
transferred Pleuroceratos to Sphindidae. However, Tihelka
et al. (2020) suggested that Pleuroceratos is a member
of Phloeostichidae based on a phylogenetic analysis of
morphological characters.
Like the taxonomic case for the placement of Pleuroceratos,
we have discovered an enigmatic Burmese amber fossil that
requires a critical assessment of characters necessary for familial
placement. This new taxon has a dorsal habitus similar to
modern-day Erotylidae and Lamingtoniidae (Figure 1), though,
unlike these families that have 5-5-5 tarsomeres in both
sexes, this fossil has 5-5-4 tarsomeres, which is diagnostic
for males of several families of Cucujoidea sensu stricto
(Lawrence and ´
Slipi´
nski,2013). The position of the fossil is
therefore subjected to phylogenetic analyses, and the results
are discussed in the context of the current classification of
Cucujoidea.
Materials and methods
Materials
The Burmese amber specimen studied herein (Figures 13)
originated from amber mines near Noije Bum (26200N, 96360
E), Hukawng Valley, Kachin State, northern Myanmar. The
specimen is deposited in the Nanjing Institute of Geology and
Palaeontology (NIGP), Chinese Academy of Sciences, Nanjing,
China. The amber piece was trimmed with a small table saw,
ground with emery papers of different grit sizes, and finally
polished with polishing powder.
Fossil imaging
Brightfield images were taken using a Zeiss Discovery V20
stereo microscope. Confocal images were obtained with a Zeiss
LSM710 confocal laser scanning microscope, using the 488 nm
Argon laser excitation line (Fu et al.,2021). Brightfield images
were stacked in Helicon Focus 7.0.2 and Adobe Photoshop CC.
Confocal images were stacked with color coding for depth in
ZEN 3.4 (Blue Edition), or semi-manually stacked in Helicon
Focus 7.0.2 and Adobe Photoshop CC. Images were further
processed in Adobe Photoshop CC to adjust brightness and
contrast.
Morphological phylogenetic analysis
To evaluate the systematic placement of the new species
within Cucujoidea, we conducted formal morphological
phylogenetic analyses under weighted parsimony. The data
matrix (Supplementary Data 1, 2) was mainly derived from the
previously published dataset by Leschen et al. (2005), which has
the advantage of having been developed for Cucujoidea sensu
lato prior to the classification in Cai et al. (2022). Therefore, we
can determine if the new species is a member of Cucujoidea
sensu stricto, Erotyloidea, or Nitiduloidea with outgroups from
Cleroidea and Derodontoidea. The full matrix includes 66 adult
and 33 larval characters, among which we successfully coded 36
adult characters for the new fossil.
Both parsimony analyses were performed under implied
weights with R 4.1.0 (R Core Team,2021) and the R
package TreeSearch 1.0.1 (Smith,2021;Supplementary Data 3).
Parsimony analyses achieve the highest accuracy under a
moderate weighting scheme (i.e., when concavity constants,
K, are between 5 and 20) (Goloboff et al.,2018;Smith,
2019). Therefore, the concavity constant was set to 12 here,
as suggested by Goloboff et al. (2018). In the unconstrained
analysis, the clade support was generated based on 1,000
jackknife pseudoreplicates.
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FIGURE 1
General habitus of Alloterocucus atratus Li, Leschen Liu, and Cai gen. et sp. nov., holotype, NIGP180056, under incident light. (A) Dorsal view.
(B) Ventral view. Scale bars: 500 µm.
Since the morphology-based phylogeny of Cucujoidea was
largely discordant with the molecular phylogeny, a constrained
analysis was conducted as well (e.g., Slater,2013;Fikáˇ
cek et al.,
2020). The interrelationships among extant families were fixed
according to the synthesized tree (their figure 2) by McKenna
et al. (2019). The intrafamilial relationships within extant
Phloeostichidae and Priasilphidae were somewhat arbitrarily
decided (partly based on Leschen et al.,2005). The fossil was
allowed to move freely across the reference tree. An exhaustive
search was conducted to find the best placement for the new
genus.
The trees were drawn with the online tool iTOL 6.5.2
(Letunic and Bork,2021) and graphically edited with Adobe
Illustrator CC 2017.
Systematic paleontology
Order Coleoptera Linnaeus, 1758
Suborder Polyphaga Emery, 1886
Series Cucujiformia Lameere, 1938
Superfamily Cucujoidea Latreille, 1802
Family incertae sedis
Genus Alloterocucus Li, Leschen, Liu,
and Cai gen. nov.
Type species
Alloterocucus atratus sp. nov.
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FIGURE 2
General habitus of Alloterocucus atratus Li, Leschen Liu, and Cai gen. et sp. nov., holotype, NIGP180056, under confocal microscopy. (A) Dorsal
view. (B) Ventral view. Scale bars: 400 µm.
Etymology
The generic name is formed based on the Greek allótrios,
strange, and “cucujoid, referring to its unique character
combination within the traditional Cucujoidea. The name is
masculine in gender.
Diagnosis
Body elongate. Postocular constriction absent
(Figures 3A,G). Antennal club 3-segmented (Figure 3B).
Apical maxillary palpomere subcylindrical, apically truncate
(Figure 3A). Genal projections acute (Figure 3B). Ventral
surface of head smooth, without any grooves (Figure 3B).
Procoxal cavities externally open (Figure 3C). Mesocoxal
cavities laterally open (Figure 3D). Pro- and mesotrochantins
exposed (Figures 3C,D). Mesoventrite distinctly longer
than half-length of metaventrite. Metaventral discrimen
absent (Figure 3E). Elytra without well-developed punctures
(Figures 3H,I). Tarsi 5-5-4 (probably in male) (Figures 3C–E).
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FIGURE 3
Details of Alloterocucus atratus Li, Leschen Liu, and Cai gen. et sp. nov., holotype, NIGP180056, under confocal microscopy. (A) Head, ventral
view. (B) Antenna, ventral view. (C) Prothorax, ventral view. (D) Mid leg, ventral view. (E) Hind leg, ventral view. (F) Abdominal apex, ventral view.
(G) Head, dorsal view. (H) Scutellum, dorsal view. (I) Elytral apex, dorsal view. a1–11, antennomeres 1–11; el, elytron; gp, genal projection; lb,
labrum; lbp, labial palp; md, mandible; mstb, mesotibia; mstcn, mesotrochantin; msts, mesotarsus; msv, mesoventrite; mt, mentum; mtf,
metafemur; mttb, metatibia; mtts, metatarsus; mtv, metaventrite; mxp, maxillary palp; pc, procoxa, pf, profemur; pm, paramere; pn, pronotum;
ps, prosternum; ptcn, protrochantin; sc, scutellum; v1–5, ventrites 1–5. Scale bars: 100 µm.
Alloterocucus atratus Li, Leschen, Liu,
and Cai sp. nov.
Material
Holotype, NIGP180056 (Figures 13), probably
male (refer to Remarks), mid-Cretaceous (upper Albian
to lower Cenomanian; Shi et al.,2012;Mao et al.,
2018), from the amber mine near Noije Bum Village,
Tanai Township, Myitkyina District, Kachin State,
Myanmar.
Etymology
The specific name refers to the blackened (carbonized)
appearance of the holotype.
Diagnosis
As for the genus.
Description
Body small, elongate, about 1.62 mm long, 0.56 mm wide.
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Phloeostichidae: Bunyastichus
Phloeostichidae: Phloeostichus
Phloeostichidae: Hymaea
Phloeostichidae: Rhopalobrachium
Cavognathidae: Cavognatha
Priasilphidae: Priasilpha
Priasilphidae: Priastichus
Priasilphidae: Chileosilpha
Propalticidae: Propalticus
Laemophloeidae: Laemophloeus
Phalacridae: Acylomus
Passandridae: Aulonosoma
Myraboliidae: Myrabolia
Alloterocucus gen. nov.
Lamingtoniidae: Lamingtonium
Cyclaxyridae: Cyclaxyra
Tasmosalpingidae: Tasmosalpingus
Silvanidae: Cryptamorpha
Silvanidae: Ahasverus
Cucujidae: Cucujus
Cryptophagidae: Atomaria
Cryptophagidae: Cryptophagus
Hobartiidae: Hobartius
Kateretidae: Amartus
Nitidulidae: Australaethina
Smicripidae: Smicrips
Monotomidae: Rhizophagus
Sphindidae: Protosphindus
Protocucujidae: Ericmodes
Helotidae: Helota
Boganiidae: Paracucujus
Erotylidae: Pharaxonotha
Byturidae: Xerasia
Biphyllidae: Anchorius
Thymalidae: Thymalus
Lophocateridae: Eronyxa
Derodontidae: Derodontus
EROTYLOIDEA
NITIDULOIDEA
CUCUJOIDEA
FIGURE 4
Placement of Alloterocucus Li, Leschen Liu, and Cai gen. nov. based on the single tree resulting from the constrained parsimony analysis.
Head prognathous, not constricted posteriorly, somewhat
flattened; supra-antennal ridges or bead absent. Eyes moderately
large, somewhat protuberant, entire, finely facetted, without
interfacetal setae. Frontoclypeal suture absent; frontal carina
on each side gradually narrowed anteriorly, almost reaching
anterior end of clypeus; clypeus truncate anteriorly. Antennal
insertions located laterally, hidden in dorsal view. Antennal
grooves absent. Antennae 11-segmented, with distinct, 3-
segmented club; antennomeres 9 and 10 transverse, slightly
asymmetrical, with distinct rims. Labrum transverse, with
broadly rounded apex. Maxillary palps with terminal palpomere
relatively wide and somewhat cylindrical, not narrowed or
dilated apically. Mentum basally with a transverse depression;
deep or shallow lines extending backward from maxillary base
absent. Genae produced anteriorly and acute. Ventral surface of
head smooth, without any clear ridges or grooves.
Pronotum weakly transverse, about 1.4×as wide as
long; lateral sides subparallel, with raised border; anterior
angles slightly produced forward; posterior angles more or
less right; posterior edge slightly bisinuate; disc lacking
impressions. Prosternum in front of coxae longer than procoxal
cavity; prosternal process relatively broad, laterally margined,
with broadly rounded apex. Procoxal cavities transverse,
without trochantinal notch, externally probably broadly open,
with narrow lateral extensions. Procoxae not projecting.
Protrochantins exposed.
Scutellar shield transverse, posteriorly broadly rounded.
Elytra about 1.7 times as long as combined width and
about 2.5 times as long as pronotum; width at base
about as wide as width of pronotum; disc with scattered
setae, without well-developed punctures; sutural striae
present and complete from base to apex; epipleura
gradually narrowed posteriorly, distinct toward apex;
subapical gape absent. Mesoventrite relatively long and
broad, about as long as half maximum width. Mesocoxal
cavities moderately widely separated, open laterally, not
closed by the meeting of mesoventrite and metaventrite.
Mesotrochantins exposed. Mesometaventral junction slightly
curved posteriorly, with metaventrite and mesoventrite
coplanar. Metaventrite broad, without median discrimen.
Metacoxae strongly transverse, narrowly separated; plates
absent.
Legs relatively slender. Trochanterofemoral joints not
strongly oblique, with femora not contacting coxae. Tibiae not
parallel-sided and expanded toward apex with several stout setae
along distal end; tibial spurs 2-2-2. Tarsi 5-5-4; tarsomeres not
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Alloterocucus gen. nov.
Cyclaxyridae: Cyclaxyra
Tasmosalpingidae: Tasmosalpingus
Lamingtoniidae: Lamingtonium
Propalticidae: Propalticus
Laemophloeidae: Laemophloeus
Phalacridae: Acylomus
Passandridae: Aulonosoma, Ancistria
Thymalidae: Thymalus
Lophocateridae: Eronyxa
Cavognathidae: Cavognatha
Myraboliidae: Myrabolia
Cryptophagidae: Atomaria
Cryptophagidae: Cryptophagus
Erotylidae: Pharaxonotha
Biphyllidae: Anchorius
Phloeostichidae: Hymaea
Phloeostichidae: Rhopalobrachium
Phloeostichidae: Bunyastichus
Phloeostichidae: Phloeostichus
Silvanidae: Cryptamorpha
Silvanidae: Ahasverus
Cucujidae: Cucujus
Priasilphidae: Priasilpha
Priasilphidae: Priastichus
Priasilphidae: Chileosilpha
Agapythidae: Agapytho
Hobartiidae: Hobartius
Kateretidae: Amartus
Smicripidae: Smicrips
Nitidulidae: Australaethina
Monotomidae: Rhizophagus
Sphindidae: Protosphindus
Protocucujidae: Ericmodes
Helotidae: Helota
Boganiidae: Paracucujus
Byturidae: Xerasia
Derodontidae: Derodontus
28
37
68
8
80
21
99
22
1
27
11
11
43
88
59
17
48
45
97
11
43
3
43
93
89
9
2
92
41
61
34
24
79
85
92
CUCUJOIDEA
NITIDULOIDEA
EROTYLOIDEA
FIGURE 5
Placement of Alloterocucus Li, Leschen Liu, and Cai gen. nov. based on the single tree resulting from the unconstrained parsimony analysis.
lobed ventrally; basal tarsomeres short and subequal; apical
tarsomere longer. Pretarsal claws simple.
Abdomen with five ventrites; ventrite 1 not much longer
than 2; intercoxal process narrowly rounded apically.
Remarks
A pair of segments bearing setae protruding from the
abdominal apex are visible in the holotype, which might be
interpreted as the styli of the female ovipositor. However, the
5-5-4 tarsi in females rarely occur outside of Tenebrionoidea,
and other characters of Alloterocucus do not fit well with
Tenebrionoidea. For example, Alloterocucus does not have
the heteromeroid type trochanterofemoral joint (not strongly
oblique) nor does it have projecting procoxae, externally
closed procoxal cavities, or well-exposed protrochantins present
in some similar groups of tenebrionoids. Alternatively, the
protruding segments may be interpreted as the elongate
parameres of a male specimen, similar to what may be present
in Erotylidae. Many Cucujoidea sensu lato have dimorphic tarsal
formulae with males having 5-5-4 and females with 5-5-5, and it
is plausible that our Alloterocucus specimen is a male.
Discussion
The character combination of Alloterocucus is not
completely accordant with any present-day cucujoid or
erotyloid families. Our constrained phylogenetic analysis
(Figure 4) excludes Alloterocucus from Erotyloidea, despite
having a similar habitus to some dacnine Erotylidae.
Furthermore, we can exclude Alloterocucus from Erotyloidea
by the presence of 5-5-4 tarsomeres, and lack of visible
glandular ducts and open mesocoxal cavities, which exclude
it from Erotylidae (see below), and the absence of the
frontoclypeal suture, which excludes it from Boganiidae.
It can also be excluded from Cryptophagidae by the
open mesocoxal cavities, the subequal basal abdominal
ventrites, and the elytra with complete (albeit narrow)
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FIGURE 6
Extant representatives of Lamingtoniidae, Tasmosalpingidae, and Cyclaxyridae. (A,B) Lamingtonium loebli Lawrence and Leschen. (C,D)
Tasmosalpingus quadrispilotus Lea. (E,F) Cylaxyra politula Broun. Scale bar: 500 µm.
epipluera and no subapical gape. Alloterocucus is placed
within the Cucujoidea sensu stricto in a trio consisting of
Tasmosalpingidae, Cyclaxyridae, and Lamingtoniidae, as sister
to Lamingtoniidae.
In the unconstrained analysis (Figure 5), Alloterocucus
was also grouped together with the same trio, but as sister
to Cyclaxyridae. Therefore, we conclude that Alloterocucus
is likely a member of Cucujoidea sensu stricto and related
to these monogeneric Australasian families, which are absent
from the fossil record, apart from Cyclaxyridae known
from Burmese and Baltic ambers (Gimmel et al.,2019).
Alloterocucus shares the following characters with these families:
absence of postocular constriction, 3-segmented antennal club,
externally open procoxal cavities, laterally open mesocoxal
cavities, exposed pro- and mesotrochantins, and the absence
of metaventral discrimen. Tasmosalpingidae and Cyclaxyridae
additionally have 5-5-4 tarsi in males, and if we assume
that the specimen of Alloterocucus is a male, this will
support the classification of this genus in Cucujoidea sensu
stricto.
Alloterocucus differs from Tasmosalpingidae, Cyclaxyridae,
and Lamingtoniidae by having apically truncate terminal
maxillary palpomeres, and the group bears different habitus
and individual characters. Cyclaxyridae (Figures 6E,F) is
characterized by an ovate and strongly convex body, well-
developed antennal grooves, the absence of genal projections,
and the presence of epipleural fovea (body elongate, antennal
grooves absent, genal projections acute, and epipleural fovea
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absent in Alloterocucus). Tasmosalpingidae (Figures 6C,D) is
somewhat sinuate in outline and is moderately convex. It also
has characters including the antennal insertions exposed in
dorsal view, clear antennal grooves, confused elytral punctation,
and laterally opening setose cavities of the pronotum, which are
all absent in Alloterocucus.
Alloterocucus most closely resembles members of
Lamingtoniidae (Figures 6A,B), but lacks distinct dorsal
punctation, and the pronotal width is equal to the combined
widths of the elytra. If we make some assumptions on the
character states of the mandible (i.e., lacking a tubercle, which
can be inferred sometimes based on the shape of the clypeus),
Alloterocucus can be keyed to couplet 26 in the family-group
key provided by Leschen et al. (2005), and since it lacks the
distinctive setose cavities on the prothorax of Tasmosalpingus
Lea, Alloterocucus can be keyed further to couplet 27 containing
Lamingtoniidae and Cucujidae. Apart from the raised supra-
ocular carinae and the tarsal formula, which is 5-5-5 in
extant Lamingtoniidae, it can be placed into this family and
excluded from Cucujidae by having a well-defined antennal
club. However, if we were able to see the internal structure
of the meso-metaventral articulation, a key feature of this
couplet, then we would be able to better place Alloterocucus in
Cucujoidea sensu stricto.
Sen Gupta and Crowson (1969) excluded Lamingtoniidae
from the cerylonid series (now Coccinelloidea) by the 5-5-5
tarsal formula, and from several families of the Cucujoidea
sensu lato based on other characters, arguing that the family is
related to Languriidae (now included in Erotylidae), as proposed
by Kirejtshuk (2000) but rejected by Lawrence and Leschen
(2003) based on larval and adult characters. The open mesocoxal
cavities exclude Alloterocucus from Erotylidae, a character
shared by most members of the family (but see Yoshida and
Leschen,2020) and support its affinity to Lamingtoniidae.
Alloterocucus differs from members of Lamingtonium Sen
Gupta and Crowson by several characters, including those
mentioned above, but also the absence of curved longitudinal
grooves extending backward from the maxillary base (present
in Lamingtonium binnaburrense Sen Gupta and Crowson and
L. loebli Lawrence and Leschen but absent in L. thayerae
Lawrence and Leschen).
Two recent phylogenomic analyses recognized three
separate lineages of Cucujoidea sensu lato. Thus, it was divided
into three superfamilies by Cai et al. (2022): Erotyloidea,
Nitiduloidea, and Cucujoidea sensu stricto. However, the
relationships among the traditional cucujoid families are still
far from being settled. Many small, rare families were not
sampled in the analysis by Cai et al. (2022). McKenna et al.
(2019) presented a synthesized tree in their figure 2, with all
cucujoid families present, but some of the families (Smicripidae,
Cyclaxyridae, Cavognathidae, Agapythidae, and Priasilphidae)
were not included in their phylogenetic analysis and were
manually inserted into the synthesized tree based on the results
of McKenna et al. (2015). McKenna et al. (2015), however,
though with a broader taxon sampling, used only eight genes,
which may not be sufficient for inferring deeper interfamilial
relationships as suggested by the discrepancies between their
maximum likelihood and Bayesian inference analyses and
low support. The topologies of many groups in McKenna
et al. (2015) were largely inconsistent with the recent more
comprehensive studies, especially for deeper nodes (McKenna
et al.,2019;Cai et al.,2022). Thus, the positions of these families
remain questionable until more genetic data are available.
Although Tasmosalpingidae and Lamingtoniidae were
placed in the Cucujoidea-3 lineage (Cucujoidea sensu stricto;
Cai et al.,2022) by McKenna et al. (2019), no molecular
data exist for either family and their current placements are
based on morphology. Moreover, the inconsistency between
morphological (Leschen et al.,2005;Lawrence et al.,2011) and
molecular (McKenna et al.,2019;Cai et al.,2022) phylogenies
of Cucujoidea indicates that morphology-based studies may
not be sufficient for properly resolving the systematic positions
of cucujoid families due mainly to rampant convergences
(McElrath et al.,2015). Thus, the superfamilial attribution of
Tasmosalpingidae and Lamingtoniidae (as well as Alloterocucus)
should still be viewed as contentious. The future inclusion of
these families in a phylogenomic study will not only help better
understand their phylogenetic relationships but also shed light
on the position of the enigmatic fossil genus Alloterocucus.
Data availability statement
The original contributions presented in this study are
included in the article/Supplementary material. The original
confocal data are available in Zenodo repository (doi: 10.
5281/zenodo.6717396). Further inquiries can be directed to the
corresponding author.
Author contributions
C-YC and Y-DL conceived the study. C-YC and D-YH
acquired and processed the specimen. Y-DL and Z-HL acquired
and processed the photomicrographs. Y-DL performed the
analyses. Y-DL and RABL drafted the manuscript, to which
C-YC and Z-HL contributed. All authors commented on the
manuscript and gave final approval for publication.
Funding
Financial support was provided by the Strategic Priority
Research Program of the Chinese Academy of Sciences
(XDB26000000), the National Natural Science Foundation
of China (42222201 and 42288201), and the Second
Frontiers in Ecology and Evolution 09 frontiersin.org
fevo-10-972343 October 29, 2022 Time: 15:29 # 10
Li et al. 10.3389/fevo.2022.972343
Tibetan Plateau Scientific Expedition and Research project
(2019QZKK0706). Y-DL was supported by a scholarship granted
by the China Scholarship Council (202108320010). RABL was
funded by Strategic Science Investment Funding for Crown
Research Institutes from the Ministry of Business, Innovation,
and Employment’s Science and Innovation Group.
Acknowledgments
We are grateful to Rong Huang and Yan Fang for their
technical help with confocal imaging. The editor and two
reviewers provided helpful comments on the manuscript.
Conflict of interest
The authors declare that the research was conducted
in the absence of any commercial or financial
relationships that could be construed as a potential
conflict of interest.
Publisher’s note
All claims expressed in this article are solely those of the
authors and do not necessarily represent those of their affiliated
organizations, or those of the publisher, the editors and the
reviewers. Any product that may be evaluated in this article, or
claim that may be made by its manufacturer, is not guaranteed
or endorsed by the publisher.
Supplementary material
The Supplementary Material for this article can be
found online at: https://www.frontiersin.org/articles/10.3389/
fevo.2022.972343/full#supplementary-material
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