Description of a Cretaceous amber fossil putatively of the tribe Coprophilini (Coleoptera, Staphylinidae, Oxytelinae)
Description of a Cretaceous amber fossil putatively of the tribe Coprophilini (Coleoptera, Staphylinidae, Oxytelinae)
György Makranczy 1
Shûhei Yamamoto 0
Michael S. Engel
0 Integrative Research Center, Field Museum of Natural History , 1400 S Lake Shore Drive, Chicago, IL 60605-2496 , USA 3 Division of Entomology, Natural History Museum and Department of Ecology & Evolutionary Biology, University of Kansas , 1501 Crestline Drive - Suite 140, Lawrence, Kansas 66045- 4415 , USA 4 Division of Invertebrate Zoology, American Museum of Natural History , Central Park West at 79 , USA
1 Department of Zoology , Hungarian Natural History Museum, H-1088 Budapest, Baross utca 13 , Hungary
An unusual and well-preserved fossil staphylinid is described and figured from a single specimen in Upper Cretaceous Burmese amber. Gollandia planata gen. et sp. n. is tentatively placed in the extant oxyteline tribe Coprophilini, although it lacks a few characteristic features of present-day members of the group, likely indicating it to be either a stem group of the tribe or prove to be distinct pending future discoveries. The discovery of this genus suggests that early oxytelines were more morphologically diverse during the Cretaceous and their evolutionary history was more complicated than previously documented. Tribal placement as regards fossil oxyteline taxa is discussed.
eol>Burmese amber; Cenomanian; Mesozoic; Myanmar; new genus; new species
Copyright György Makranczy et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC
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The staphylinid subfamily Oxytelinae Fleming, 1821 is a relatively large group with
over 2049 valid extant species placed in 40 genera
. Oxytelines are
distributed worldwide and have proven to be remarkably diverse. This diversity is so far
not fully known as in several geographical areas the species are incompletely known,
in many cases a vast portion (up to 80%) still await formal description. The generic
, which was also a first attempt at a phylogenetic analysis,
set the foundation for a better understanding of relationships within the subfamily and
for all subsequent revisionary and evolutionary research on oxytelines.
Despite Herman’s (1970) monumental study, the classification of tribes within
Oxytelinae remains unsettled. The most primitive oxytelines
(formerly as tribe
Deleasterini, sensu Makranczy 2006, based on abdominal segments with only one pair of
are now often split into three separate tribes: Deleasterini Reitter, 1909,
Euphaniini Reitter, 1909, and Syntomiini Böving & Craighead, 1931. The higher
oxytelines, comprising 98% of the described valid species in the subfamily, are variously
classified in the more primitive Coprophilini Heer, 1839, as well as the now widely
accepted Blediini Ádám, 2001 and Planeustomini Jacquelin du Val, 1857. The more
derived clades seem to belong into a once again unified Oxytelini
, although this remains debated and awaits support from molecular studies.
The tribe Coprophilini is currently without identified synapomorphies, and is
instead defined by a lack of features of the more derived lineages (i.e., it is presently
circumscribed by putative plesiomorphies, may be paraphyletic, and is in need of
considerable revisionary and phylogenetic exploration). The extant coprophilines are
characterised by the following combination of traits: mesocoxae narrowly separated
by mesosternal process or contiguous, tarsal formula 5-5-5, abdominal segments with
two pairs of laterosclerites, and with only six sternites visible. According to
, the tribe contains three extant genera, Coprophilus Latreille, 1829,
Coprostygnus Sharp, 1886, and Homalotrichus Solier, 1849, although a poorly described genus,
Coprotrichus Hayashi, 2005 (based on a single species from Japan) was later added and
is presently considered as valid but requires detailed study. The number of species in
these genera is not great; Coprophilus stands in the last catalogue with 30 valid species
, Homalotrichus and Coprostygnus are being revised by the first author,
standing with at least 13 and five species, respectively (Makranczy, unpubl. data).
Coprophilus is widespread in the Northern Temperate zone, Homalotrichus is known from
Australia (including Tasmania) and South America, while Coprostygnus is confined to
New Zealand. It is remarkable that all of these species prefer cold climates, often
occurring at the highest elevation where one can find oxytelines, up to 4000–4200 m.
The various records of fossil Oxytelinae and its related subfamilies were
Cai et al. (2017)
. Hitherto, the only definitive fossil Coprophilini described
is a rather poorly preserved compression fossil (without counterpart), Mesocoprophilus
clavatus Cai & Huang, 2013. A further fossil genus, Sinoxytelus Yue, Zhao, & Ren,
2010 was subsequently transferred to Coprophilini, but this placement is tentative as
the abdomen has basolateral ridges, a trait of Oxytelini. The genus originally contained
three extinct species
(Sinoxytelus euglypheus Yue, Zhao, & Ren, 2010, S. breviventer
Yue, Zhao, & Ren, 2010, and S. longisetosus Yue, Zhao, & Ren, 2010)
from the Yixian
Formation (Lower Cretaceous, ca. 126 Mya, 41°36’44”N, 120°49’48”E), Liaoning,
(Yue et al. 2010)
, and a fourth taxon, S. transbaicalicus Cai, Yan, &
Vasilenko, 2013 was later described from the Urey beds (Lower Cretaceous, 50°38.730’N,
112°50.338’E), Transbaikalia, Russia
(Cai et al. 2013)
. Here we describe a new genus
and species from the Upper Cretaceous amber of northern Myanmar.
This new taxon represents the second fossil occurrence of Oxytelinae documented
from Mesozoic amber, and is also the oldest amber inclusion presently recorded for the
subfamily along with Prajna tianmiaoae
Lü et al., 2017
, a species of Thinobiini (a more
derived tribe) described from the same deposit.
Materials and methods
Specimen photography was done with the amber piece mounted on a small plastic
plate surface with a drop of viscous glycerine covered with a glass cover slip to
eliminate distortions from the otherwise rounded amber surface. The habitus photographs
were made with a Canon 5D Mark III camera and C Canon MP-E 65mm f/2.8 1–5×
macro lens with two Canon Macro Twin Lite MT-24EX flash units and a Canon
Speedlite 430EX III-RT flash unit standing on the shoe foot directly in front of the
specimen (shooting directly into the head of the specimen). The light was diffused
by a single ring of mylar. Raw photograph files were imported to Adobe Lightroom
5.7.1, and layers stacked with ZereneStacker (Richland, Washington, USA). Details of
the specimen were photographed with a Canon EOS 6D camera attached to a Leica
M205 C stereomicroscope with the help of a Canon EOS Utility 126.96.36.199 software,
before being stacked using the same software as previously mentioned. Abbreviations
for measurements are defined as follows:
head width with compound eyes;
head width at temples;
maximum width of pronotum;
approximate width of shoulders;
maximum width of elytra;
maximum width of abdomen;
head length at the middle-line from front margin of clypeus to the beginning
compound eye length;
length of temple;
length of pronotum at the middle-line;
length of elytra from shoulder;
length of elytra from hind apex of mesoscutellum;
fore-body length (combined length of head, pronotum, and elytra);
approximate body length.
The specimen is exceptionally well preserved but in a rather unfortunate position
within the amber piece. Under UV-light examination it can be seen that the specimen
is sitting within a dip in the internal flow of the amber (the amber flowed in layers
when it was originally exuded from the tree and the beetle is in a dip within these
flows). The result of its placement within the dip in the flow means ideal, clear images
cannot be produced at high magnification unless some of the flows can be polished
away. Whoever made the original preparation (probably local workers in Myanmar)
polished the specimen too close to the amber surface and cut the piece poorly. The
result is that it is now impossible to cut and polish the piece closer to minimize the
optical impact of the flow lines.
The recent commercial amber mines are located in the Hukawng Valley (26°16.5’N,
96°34.0’E), Kachin, northern Myanmar. The minimum age of the amber is
estimated to be 98.79 ± 0.62 Mya
(by radioisotope dating of zircon crystals obtained from
the volcanoclastic matrix, Shi et al. 2012)
, and so just slightly into the base of the
Cruickshank and Ko (2003)
Ross et al. (2010)
Grimaldi and Ross
provide a geological account of the deposits, and these authors also note that
many of the amber pieces appear to have at some point eroded from sediments and
been redeposited, at least suggesting the possibility that the inclusions could be slightly
older, perhaps from the latest Albian. Recent studies speculate that the West Burma
Plate/Block (west of the Sagaing fault line in Myanmar) was of Gondwanan origin
, and the resin-producing tree was hypothesized to be of Agathis Salisb.
(Poinar et al. 2007)
. The paleoclimate of Burmese amber producing
forests were suggested to be tropical with an average temperature range of 32–55 °C
(Grimaldi et al. 2002; Ross et al. 2010)
Family Staphylinidae Latreille, 1802
Subfamily Oxytelinae Fleming, 1821
Tribe Coprophilini Heer, 1839
Gollandia gen. n.
Type species. Gollandia planata sp. n., (described below).
Diagnosis. Head. Head somewhat retracted under large pronotum; head capsule
rather short. Epistomal sulcus not well visible, but presence suggested by a tranvserse
‘run’ of air between amber and cuticle. Supraantennal prominences weak.
Antennomeres with long tactile setae near apices (prominent on articles 3–11). Labial palp
trimerous, basal two palpomeres rather stout, last palpomere thin. Labrum with two
thick, forward-directed setae. Mandibles not prominent, apices acute. Maxillary palp
tetramerous, basal three palpomeres moderately elongate, last palpomere much wider
and long, not reduced, apex pointed. Gular sulci seemingly widely separated at base
but confluent anteriorly (this area is not well visible as preserved). Neck separated by
gentle constriction and (at least laterally) a groove. Thorax . Pronotum strongly
explanate, margin slightly reflexed, marginal bead present, lateral edge finely serrate/
sinuous. Laterally with a strong seta at each of ‘anteroangularis’ and ‘lateralis’ positions,
plus strong seta on both sides well inside lateral margin at about 1/3 length, posterior
edge appearing slightly concave (might be artefact of preservation). Pronotal disc with
shallow impressions, with fine and dense punctation and setation. Procoxae
contiguous, projecting; procoxal fissure present and open (Figure 7). Mesoscutellum (Figure
8) with apex exposed and somewhat impressed without distinct pattern. Elytra finely
and randomly punctate. Mesocoxae narrowly separated by mesosternal process (Figure
9). Legs slender (metatibia especially elongate), with regular rows of tibial spines (more
slender than strong), and a conspicuous mesotibial spur (and a second spur half size at
half-length towards femoral joint). Tarsal formula 4-4-4, no tarsal lobes (Figure 10),
but empodial setae strong (Figure 11). Elytra with epipleural ridge, seemingly with a
fine and shallow dorsal groove following it from inside, epipleura strongly deflexed
and rather wide but epipleural fold thin to inconspicuous. Post-scutellar area with a
pair of elongate impressions along suture. Shoulders prominently developed, narrowly
rounded, even slightly projecting forward in relation to anterior edge at mesoscutellar
area, posterior margin slightly oblique but straight from suture to outer 3/4, slightly
incurved (concave) in outer 1/4 thereby producing a somewhat sharp outer corner
in dorsal view. Abdomen. Abdomen with only six visible segments (not counting
segments IX–X, often retracted under VIII), second abdominal segment not developed.
With two pairs of laterosclerites. Apex of tergite VII seemingly without well-developed
palisade fringe (difficult to judge; an air bubble under this structure obscures almost its
entire width), apex of segment conspicuously widening (not narrowing to base of next
segment), surface somewhat concave. Tergite VIII with apical edge truncate medially
or slightly concave. Apex of sternite VIII without modification.
Differential diagnosis. All extant Coprophilini have a 5-5-5 tarsal formula, and
even the fossil genus Mesocoprophilus has five tarsomeres, so the 4-4-4 condition in
Gollandia is significant. The new genus differs greatly fromMesocoprophilus in the antennal
structure, stout and short in Mesocoprophilus, slender and elongate with well-developed
tactile setae on all antennomeres in the present fossil. The neck (lateral constriction,
postoccipital groove) also differentiates this genus from Mesocoprophilus where these
features are absent. The lack of striae or puncture rows on the elytra makes this genus
distinct from all extant Coprophilini, while a distinction from Mesocoprophilus cannot
be made as that fossil lacks its dorsal portion
(Cai and Huang 2013)
. The present fossil
is also peculiar in the slender and elongate appendages. The present-day representatives
of Coprophilini lack such strongly formed, almost forward-projecting shoulders and
the new genus has more slender antennae and palp, more slender tibiae, a procoxal
cavity far removed from the pronotal margin, a prominently explanate pronotum, and
the mesosternal process extending much more posteriorly. Two unusual traits for this
subfamily are the posteriorly slightly incised elytral corners and the cylindrical, wide
apex of segment VII (not narrowing to the base of segment VIII), both features
otherwise characteristic of the subfamily Aleocharinae.
Systematic placement. The only feature that clearly unites the fossil with extant
Coprophilini is the lack of the well-developed second sternite. Beyond that, the head
shape is reminiscent of Homalotrichus, while the pronotum bears some similarity to
that of some Coprophilus (e.g., Coprophilus striatulus (Fabricius, 1793) plus its close
relatives) and to a lesser extent some Homalotrichus (e.g., Homalotrichus impressicollis
Solier, 1849), but none of these are as explanate as in the fossil.
Etymology. The new genus is named after Susan Golland, exhibition developer at
the Field Museum of Natural History, Chicago, whom the first author met at 10:32am
on 14 March 2018 in front of Crystal Maier’s office. The fossil specimen described here
was shown to him by the second author later on the same day. The gender of the name
is considered feminine.
Gollandia planata sp. n.
Holotype. Sex unknown, probably male, in a flattened drop shaped, light yellow
amber piece (20.0 × 9.9 × 4.5 mm, 0.98g): “FMNHINS 3729858 ex S. Yamamoto
collection (SYAC0482)” deposited in Field Museum of Natural History (Chicago, USA).
Locality and horizon. Noije Bum hill near Tanai Village, SW part of Hukawng
Valley (SW of Maingkhwan), Kachin State, northern Myanmar; lowermost
Cenomanian, Upper Cretaceous.
Diagnosis. As for the genus (vide supra).
Description. Measurements: HW = 0.45; TW = 0.41; PW = 0.64; SW = 0.59;
MW = 0.68; AW = 0.70; HL = 0.29; EL = 0.10; TL = 0.04; PL = 0.50; SL = 0.66; SC
= 0.55; FB = 1.47; BL = 3.29 mm (all measured from dorsal view). Habitus: General
habitus as in figures 1–6. Colour reddish dark brown. Body moderately lustrous,
covered with fine microsculpture and forebody finely, not very densely setose. Abdomen
with longer and stronger lateral setae posteriorly. Head. Head rather short.
Antennae rather elongate, scape almost twice as wide as pedicel and not much longer,
second antennomere (pedicel) more than 3.5× as long as wide, third antennomere (first
flagellomere) slender at base and almost as long as previous. Further antennomeres
spindle-shaped and each with rudimentary basal dish, gently constricted above them.
Antennomeres 4–7 at least 2.5× as long as wide, from antennomere 8 becoming wider,
gently clubbed, last three antennomeres only about 1.5× as long as wide. Compound
eyes more than 2× as long as weakly formed temples. Neck not constricting strongly.
Thorax . Pronotum rather large, widest point slightly before middle with both anterior
and posterior corners rather narrowly rounded, lateral margin slightly concave before
quite acute posterior angles. Surface finely microsculptured, thereby punctation partly
obscured. Disc transversally impressed before base (in a curved fashion), also with a
Figures 3–4. Gollandia planata gen. et sp. n. photographed with macro lens and three flash units. 3 dorsal
view 4 ventral view.
Figures 5–6. Gollandia planata gen. et sp. n. photographed through microscope, strong backlighting.
5 dorsal view 6 ventral view.
semi-triangular mid-longitudinal impression anteriad; rather large but shallow
paralateral depressions on sides. Elytra. Elytra together just slightly broader than pronotum,
trapezoidal, shoulders well developed, narrowly rounded, even slightly projecting
forward in relation to anterior edge at mesoscutellar area. Dorsal surface finely punctate
and setose, no major lateral setae, epipleural ridge with moderately long setae at regular
intervals. Abdomen. Sides of abdomen gently curved, almost parallel. Surface of tergites
with moderately fine, longitudinally elongate punctures, apical edges of tergites (up to
tergite VI) with row of equal-sized setae at regular intervals. Specimen is without any
feature suggesting strong sexual dimorphism. No genital traits observable.
Etymology. The specific epithet is a Greek adjective derived from platys (= wide)
and refers to the pronotum of the species being unusually explanate.
Preservation. The specimen is exceedingly well preserved, with the hind wings
unfolded over part of the abdomen, minor air bubbles under segmental edges, a thin
air layer over some sculptured dorsal parts, and the ventral side exceptionally clearly
visible. As explained before, the specimen is sitting within a layer of resin covered by
another layer, and this creates an effect similar to the specimen being glued to a glass,
evident in the photos of the ventral side. The legs are somewhat distorted (but each pair
is almost perfect on one side). Primitive oxytelines often have distinctive coxites and
styli in females (if not exposed, then setation gives them away), and in their absence
the specimen is presumed to be a male.
There can be a great debate on how to place fossil species in higher taxa when the
classification is otherwise based entirely on present-day species. Naturally, fossil species
placed cladistically within the crown group are not difficult, but when potential stem
groups are discovered some difficulties and strong differences of opinion arise. Does
one include them within the formal group, necessitating a new circumscription of the
taxon boundaries in order to accommodate the fossil, or, at another extreme, more
radically establish a new group for the fossil as a potential sister to its extant relatives?
The latter will inevitably lead to a proliferation of meaningless and often monobasic
groups based on limited characters (e.g., often lacking critical data on genital traits)
and collectively forming a pectinate stem to any lineage circumscribed solely on the
basis of its extant constituents, the end result becoming a classification of little
explanatory power. Ideally, there one desires a balance between maintenance of a good
diagnostic power and keeping the classification simple while simultaneously reflecting
the hierarchical relationships supported among the various taxa being classified and
granting the system maximal explanatory and predictive significance. These goals are
sometimes simultaneously achieved, but more often than not the former objective
becomes muddied while attempting to adequately reflect the latter. This challenge is
particularly great for ancient groups, such as the Oxytelinae whose history goes back
at least 150 Mya, where there has been inevitably considerable extinction over the
intervening epochs between the first divergence of a given clade and its modern fauna.
Cretaceous deposits will undoubtedly supply for generations to come a continuous
stream of unusual fossil species that will force us to rethink our estimates of
relationship and concomitantly the classifications from which they are built. Descriptive
(Grimaldi and Engel 2007)
has undergone an unprecedented boom in the past
few years with new techniques (tomography, confocal microscopy) providing details
that bring the examination of fossil morphology more comparable to that of extant
species. The result of this increase in available character data and extinct taxa will be
finer phylogenetic placement of peculiar fossil species and, hopefully, greater clarity on
how best to tackle each classificatory alteration as they arise.
In the case of the presently known fossil oxytelines or putative oxytelines this
challenge is acute as there are limited character data available. The four fossil species
presently placed in Sinoxytelus possess a mixture of ancient and relatively modern traits.
The basolateral ridges on the abdominal tergites are a trait of the tribe Oxytelini, while
the somewhat reduced second abdominal sternite suggests placement in more
primitive tribes. A solid age estimate is available for part (Lujiatun Bed) of the Yixian
Formation and at approximately 126 Mya, or Aptian
(Chang et al. 2017)
. If Sinoxytelus is
truly either a stem group to Oxytelini or Oxytelini + other higher oxytelines, then the
subfamily Oxytelinae as whole was apparently already diverse by the latter part of the
Early Cretaceous. It seems apparent that there has been considerable extinction within
the subfamily, resulting in only a few lineages surviving and diversifying to their
present state. These fossils may be rather distantly related to the ancestors of the present
Coprophilini or Oxytelini, with potentially numerous additional extinct stem groups
(yet to be discovered) present before the divergence of the crown groups of these latter
tribes. Characters that
Cai et al. (2013)
cite for placing Sinoxytelus within Coprophilini
(e.g., metasternal process slightly protruding but not meeting mesosternal process) are
more indicative of particular genera rather than the tribe, as there is considerable
variation within the present day genera for these traits and are not strictly diagnostic for
coprophilines (Herman 1970).
The current Burmese amber fossil species has a similarly conflicting combination
of traits, on the one hand it can be placed in Coprophilini because of the
plesiomorphic condition of the basal abdominal segments (although the tribe is presently defined
on putative plesiomorphies and so this feature alone indicates nothing more than the
potential for the fossil to belong therein or to belong to stem-group coprophilines,
assuming the tribe is truly monophyletic). On the other hand, the apomorphically
reduced number of tarsomeres, is a derived feature, but currently cannot be considered
anything more than autapomorphic for the genus. Thus, given the lack of abundant
evidence definitively demonstrating its phylogenetic placement relative to modern
oxyteline genera, we prefer to tentatively consider the genus as a member (a stem group
member) of Coprophilini. Hopefully, in time further material and other fossil species
will be discovered that will ultimately permit a clarification of its relationships along
with its broader implications toward affinities among lineages of Oxytelinae, and at
which time a redefinition of oxyteline tribes may be attempted.
We are grateful to Al Newton (Field Museum of Natural History, Chicago) for
providing an initial set of notes and comments on the specimen, and to Aslak Kappel
Hansen and Janina Lisa Kypke (University of Copenhagen, Denmark) who aided the
first two authors with taking photographs and experience with photographing amber
specimens. A Visiting Scholarship from the Field Museum supported the first author
(GyM) (12 March–5 April 2018) for portions of this research. The second author (SY)
was supported by a Japan Society for the Promotion of Science (Tokyo, Japan)
Overseas Research Fellowship (29-212).
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