Mesophyletis calhouni (Mesophyletinae), a new genus, species, and subfamily of early cretaceous weevils (Coleoptera: Curculionoidea: Eccoptarthridae) in burmese amber

2006·4.5 MB·

by  George Poinar

PROC. ENTOMOL. SOC. WASH.
108(4), 2006, pp. 878-884
MESOPHYLETIS CALHOUNI (MESOPHYLETINAE), A NEW GENUS, SPECIES,
AND SUBFAMILY OF EARLY CRETACEOUS WEEVILS (COLEOPTERA:
CURCULIONOIDEA: ECCOPTARTHRIDAE) IN BURMESE AMBER
GEORGE POINAR, JR.
Department of Zoology, Oregon State University, Corvallis, OR 97331, U.S.A.
(e-mail: [email protected])
Abstract.4A new subfamily, genus and species of weevils (Coleoptera: Curculio-
noidea; Eccoptarthridae: Mesophyletinae: Mesophyletis calhouni Poinar) are de-
scribed from Cretaceous Burmese amber. This fossil differs from all previously
described Cretaceous weevils in having definite geniculate antennae with an elongate
scape and antennal scrobes, prolonged trochanters, toothed tarsal claws, and long
pedunculate lobes on the third tarsal segment. The presence of the latter characters
suggests that its life style was arboreal.
Key Words: Eccoptarthridae, Mesophyletinae, new subfamily, Mesophyletis, new
genus, Mesophyletis calhouni, new species, Burmese amber, Early
Cretaceous, Curculionoidea
Mesozoic weevils are uncommon and Amber from Burma occurs in lignitic
almost all belong to the primitive weevil seams in sandstone-limestone deposits
Division Orthoceri, which include species in the Hukawng Valley. Nuclear mag-
with straight antennae (Alonso-Zarazaga netic resonance (NMR) spectra of amber
and Lyal 1999; Gratshev and Zherikhin samples taken from the same locality as
2003; Ponomarenko 1995; Zimmerman the fossil indicates an araucarian (possi-
1993, 1994a). Thus it was of interest bly Agathis) source of the amber (Lam-
when a weevil in Early Cretaceous bert and Wu, unpublished research
Burmese amber was discovered with 2002). Palynomorphs obtained from
definite geniculate antennae. The present the amber beds where the fossil piece
study describes this weevil and discusses originated have been assigned to the
its possible biological affiliations based Upper Albian of the Early Cretaceous
on functional morphology. (100-110 mya) (Cruickshank and Ko
2003).
MATERIALS AND METHODS
The Burmese amber weevil is well
The amber piece containing the fossil preserved and complete, with all its
is roughly square in outline, measuring appendages still attached (Fig. 1). Since
8 mm long by 7 mm wide and 3 mm in it could not be placed in any extant or
depth. Observations, drawings, and extinct genus, it is described below in
photographs were made with a Nikon a new subfamily of the family Eccoptar-
SMZ-10 R stereoscopic microscope and thridae. Systematic treatment of families
Nikon Optiphot compound microscope and subfamilies is based, in part, on that
with magnifications up to 600. of Alonso-Zarazaga and Lyal (1999).
VOLUME 108, NUMBER 4 879
Superfamily Curculionoidea Latreille pronotum transverse; trochanters en-
Family Eccoptarthridae Arnoldi 1977 larged or prolonged; tarsal claws paired,
widely divergent, simple, bifid or appen-
Diagnosis.4Small to medium-sized
diculate; abdominal ventrites with straight
weevils (under 10 mm); rostrum medium
sutures; elytral tips obtuse, pygydium
to long, usually slender, nearly straight
exposed.
to slightly curved; antennae straight or
Diagnosis.4The diagnostic characters
elbowed (geniculate), normally attached
of this fossil subfamily are geniculate
near middle of rostrum; club loose or
antennae, enlarged or prolonged tro-
somewhat compact; eyes round, small to
chanters, and exposed pygydium. The
large, often positioned closer to upper
genus Cretonanophyes Zherikhin is trans-
surface of head; pronotum transverse,
ferred from the Eccoptarthrinae to the
almost flat to curved; legs mostly short;
Mesophyletinae because it contains the
forecoxa large, often situated close to
above mentioned diagnostic characters.
hind margin of prothorax; femora thick-
Comment.4A drawing of the Late
ened, unarmed; tibia straight, often
Cretaceous Cretocar luzzi Gratshev and
emarginate; tarsi variable, tarsus | often
Zherikhin (2000) shows one antenna
widened, tarsus 3 distinctly bilobed:
straight and the other elbowed; however,
claws simple or divided: elytra broad or
no mention is made in the description as
elongate, nearly flat to slightly concave,
to whether the antennae are geniculate or
with irregular or regular rows of fine
not and the ratio of scape/funicle is 0.36,
punctures; wings present; scutellum pres-
which is low for geniculate antennae. An
ent or absent; abdomen with at least
examination of select extinct and extant
segments 244 subequal.
weevil species of various taxa by the
Comments.4The diagnosis provided
author showed that the great majority
here is based on characters common to
with geniculate antennae have a scape/
the genera listed by Alonso-Zarazaga
funicle ratio greater than 0.50. Both
and Lyal (1999) in the subfamilies
Mesophyletis and Cretonanophyces have
Eccoptarthrinae Arnoldi and _ Baissor-
a scape/funicle ratio greater than 0.50.
hynchinae Zherikhin. I follow Zimmer-
man (1994a) in establishing family status Mesophyletis Poinar, new genus
for the carids, thus removing the Carinae
Type species: Mesophyletis calhouni Poinar.
from the Eccoptarthridae. Thus, the
Eccoptarthridae consists only of fossil Description.4With characters listed
genera. The characters presented under under subfamily description; eyes posi-
the family diagnosis are general because tioned on dorsolateral side of head;
they are usually the only ones observable antennal insertions on side of and
in fossils, especially compression fossils. approximately in middle of rostrum;
Many crucial characters (genitalia, antennal scape long, reaching anterior
mouthparts, structure of antennal club, border of eye; scape/funicle ratio, 0.82;
etc.) are not included because they are antennal scrobes exposed in side view;
rarely preserved, or if they are preserved, pronotum transverse; forecoxa large,
are obscured. close to hind margin of prothorax; tarsal
claws toothed.
Mesophyletinae Poinar, new subfamily
Diagnosis.4 Mesophyletis differs from
Description.4Antenna geniculate with all previously described Mesozoic weevils
elongate scape and scrobes; antennal in having pedunculate lobes of the third
funiculus 647 segmented; antennal club tarsal segments and bifid claws. Also, its
loosely 3 segmented; eyes large, round; geniculate antennae with an elongate
880 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
my
Figs. 145. Mesophyletis calhouni in Burmese amber. 1, Lateral view (right side) of holotype female.
Bar = 691 um. 2, Lateral view of metatibia showing serrations (arrows). Bar = 127 um. 3, Lower portion
of rostrum showing exodont mandible (arrow) Bar = 98 um. 4, Pedunculate lateral lobes and elongate
terminal mesotarsal segment with pointed inner (arrow) and outer teeth of bifid claws. Bar = 100 um. 5,
Terminal metatarsal segment with blunt inner (arrow) and pointed outer teeth of claws (arrow). Bar =
100 um.
scape and antennal scrobes separate it Mesophyletis calhouni Poinar, new species
from all Mesozoic weevils except Creto- (Figs. 147)
nanophyes longirostris Zherikhin. Creto- Description.4Female; characters as
nanophyes differs from Mesophyletis in listed under family and generic diagno-
its longer rostrum, width of its ventrites, ses. Body length 2.8 mm.
position of the pro- and mesocoxae, and Head: Head deflexed, 1.3 mm long;
its simple claws. eyes round, protruding from head margin;
Etymology.4Mesophyletis is from the located at base of rostrum; rostrum long,
Greek <meso= for something between slender, curved more at base than apex;
and the Greek <8phyle99 for tribe or race. antennal scape 419 um long, swollen at
The gender is feminine. apex; antennal funiculus composed of 7
VOLUME 108, NUMBER 4 881
Figs. 647. Mesophyletis calhouni in Burmese amber. 6, Lateral view (left side) of holotype female. Note
geniculate antenna and prolonged trochanters. Bar = 505 um. 7, Detail of antenna. Note long scape and
loose club. Bar = 95 um.
segments, length of funicular segments: 1: denticles absent on protibia; tarsi 5-
95m, -2> 89. tim, 3: 63 um, 4:68 pm,, 5: segmented, first tarsal segment straight
Sse. FO. 9m. 7: 53) um:, club. com- to slightly notched; second tarsal seg-
posed of three loosely joined segments, ment explanate and notched at tip; third
length. of.clubssegments: 12, 116m, 2: tarsal segment greatly bifid with pedun-
hOStpumes $33, 13 ums first and..second culate lateral lobes; fourth tarsal segment
funicular segments subequal in length; miniscule, located at base of fifth seg-
funicular segments with hair bands; club ment; fifth tarsal segment greatly elon-
segments uniformly covered with dense gate, narrow at base, tarsal claws widely
hairs; ratio of scape/funicle, 0.82; exodont divergent, bifid (on pro- and mesotarsi)
mandibles positioned vertically; maxillary or appendiculate (laminate) (on meta-
and labial palps not observed. tarsi); elytra bicolored, with prominent
Thorax: Brown, pronotum 890 um shoulders; elytral vestiture fairly dense;
long, transverse; densely pubescent; with anterior third and posterior sixth with
rounded edges; lacking lateral carina; castaneous colored squamae, remainder
procoxa prominent, separated by a keel- black except for elliptical castaneous
like prosternum; mesocoxae closely ap- spot in anterior mid-portion of black
proximate; metacoxae well separated; area; elytra tapered posteriorly, with
trochanters prolonged; femora clavate, prominent suture extending total length:
somewhat flattened, unarmed; meso- and each elytron with approximately 25 rows
metafemora curved; tibiae strongly flat- of depressed setae; elytral apices bluntly
tened; pro- and mesotibiae bearing well- rounded, exposing pygydium; elytral
developed spine at apex; metatibia ser- striae not visible; elytral surface, espe-
rulate with 2 broad symmetrical spines at cially apical half, covered with minute
apex; smaller denticles on mesotibia; protuberances; scutellum not visible.
882 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
Abdomen: Dark brown; 2.2 mm long; primitive forms possess a short scape and
five ventrites present, all leveled; 244 the advanced ants a longer one. Benefits
subequal in width; tip of abdomen of a longer scape in ants are considered
rounded, with two small protruding to be improved cardanic movements
appendages considered to be styli of the between the scape and funicle, thus
hemisternites; pygidium exposed. enabling better inspection of the brood
Male unknown. and recognition of food items (Baroni
Material examined.4Holotype female Urbani 1989). While brood care cannot
in Burmese amber from the Hukawng be considered the selective force for a long
Valley, deposited in the Ron Buckley scape in weevils, being able to extend the
amber collection located at 9635 Sumter antennal clubs for better inspection of
Ridge, Florence, KY, 41042. This col- plant surfaces for feeding and oviposition
lection is available to scientists for study, and detecting sensory signals from plant
and plans are underway to transfer it to hosts could be important factors, espe-
a Major museum. cially in the Cretaceous when the angio-
Etymology.4tThe specific epithet <8cal- sperms were evolving and forests were
houni=9 is for the memory of John becoming more heterogeneous.
Calhoun. When dealing with fossil forms, espe-
Comment.4It is unusual for the shape cially compression fossils, it is often not
of the claws to differ on the same possible to determine if the antennae are
individual. While on the pro and meso- geniculate or not and the scape/funicle
tarsi both the inner and outer teeth are ratio provides a good indication of this
pointed (bifid), on the metatarsi the character. While preliminary observa-
inner tooth is blunt tipped (appendicu- tions indicate that the majority of weevils
late) and the outer one is pointed with geniculate antennae have a scape/
(Figs. 4, 5). This difference of claw types funicle ratio over 0.50, there are excep-
is not due to the viewing angle. The other tions. Some orthocerus brentids have
interesting and apparently unique feature elongate first antennal segments and
for at least fossil weevils is the peduncu- some gonatocerus tanymecines possess
late lobes of the third tarsal segments. short scapes.
Mesophyletis possesses characters typ-
DISCUSSION ical of members of the Caridae, Apioni-
In his treatise on Australian weevils, dae, and Nanophyidae (Thompson
Zimmerman (1993; 1994a, b) divided the 1992). With the Caridae, the fossil shares
Superfamily Curculionoidea into three a fairly dense elytral vestiture, masked
Divisions. The Orthoceri included the elytral striae, a loose antennal club, a 7-
primitive weevils with straight antennae, segmented funicle, antennae inserted on
the Gonatoceri contained the advanced the side of the rostrum, approximate
weevils with geniculate antennae, and eyes, tarsi with divaricate claws, emar-
the Heteromorphi consisted of those ginate first tarsal segment, leveled and
species that did not clearly belong to subequally long abdominal ventrites, and
either of the above but showed some a serrulate outer edge of the meso- and
features of each. In this classification, metatibiae. Characters that Mesophyletis
Mesophyletis would fall into the Division shares with the Apionidae and Nano-
Heteromorphi. phyidae are listed in Table 1.
The shift from a short toa long scape in It is difficult to place Mesophyletis in
weevils is an evolutionary trend that also the Apionidae, in spite of its 7-jointed
occurs in the Hymenoptera, especially in funicle and bifid claws, because that
social forms like ants where the more group typically has straight antennae
VOLUME 108, NUMBER 4 883
Mabie: A comparison of characters of Apionidae, Nanophyidae, and Mesophyletis (characters for
Apionidae and Nanophyidae taken from Zimmerman 1993).
rr
Character Apionidae Nanophyidae Mesophyletis
Elongated present present present
trochanters
Antennal structure straight geniculate geniculate
Antennal funiculus (6)47 jointed 4-6 jointed 7- jointed
Antennal club mostly fused mostly loosely loosely jointed
jointed
Antennal insertions underside or beneath side of rostrum side of rostrum
rostrum
Antennal scrobes concealed from side view exposed in side view exposed in side view
Eye position well separated approximate approximate
Scutellum exposed concealed concealed
Tarsal claws often toothed, never connate never toothed toothed, divergent
Mesocoxal cavities coalesced or closely well separated closely approximate
approximate
Abdominal ventrites normal, straight sutures unequal, sides curved normal, straight sutures
with a fused antennal club and a visible An early angiosperm host for Meso-
scutellum. However, as pointed out by phyletis is possible since members of
Wanat (2001), some _ basal apionids the Apionidae and Nanophyidae devel-
(Lepanomus Balfour-Browne) havea loose op predominately in vegetative tis-
antennal club. The fossil does not fit with sues, galls, fruits, and seeds of angio-
the Nanophyidae, even though it pos- sperms (Zimmerman 1993). In fact,
sesses geniculate antennae, a loosely 3- nanophyids and other seed beetles are
segmented antennal club and _ closely important predators of dipterocarp seeds
approximated eyes, because nanophyids in southeastern Asia, at times destroy-
have antennal funicles composed of only ing between 60 and 100% of the seed
446 segments, the mesocoxal cavities are crop (Lyal and Curran 2003). It is
well separated, the tarsal claws are never interesting that the fossil originates from
toothed, and the ventrites are unequal an area where dipterocarps are dominant
and curved at the sides. in forests with an annual rainfall of
The bilobed tarsi suggest that Meso- around 100 inches (Stamp 1925). How-
phyletis was an arboreal species (Blatch- ever, a gymnosperm host cannot be ruled
ley and Leng 1916) and the protective out since some present day representa-
color pattern on the elytra indicates that tives of the Apionidae develop on con-
it was exposed during periods of activity. ifers. The North American Podapion
The long rostrum implies that it fed and gallicola Riley develops in galls on pines
possibly oviposited within plant tissues, (Blatchley and Leng 1916) and all species
such as stems, developing flowers, and of the endemic Australian genus Rhinor-
seeds. The saw-tooth-like serrulations on hynchidius Voss develop in galls on the
the metatibia could have supported it leaves and stems of members of the
while feeding or making ovipositional genus Callitris in the Cupressaceae
cavities. The pedunculate lobes on the (Zimmerman 1994b).
third tarsal segments and the extended
terminal tarsal segments possibly were ACKNOWLEDGMENTS
modifications for grasping smooth sur- I thank Ron Buckley for loaning the
faces, such as angiosperm leaves or fossil for study and Héléne Perrin, Alex
glabrous seed pods. E. Brown, and Roberta Poinar for com-
884 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
ments on earlier drafts of this manu- 241-254. In Grimaldi, D., ed. Studies on
script. Grateful appreciation is extended Fossils in Amber, with Particular Reference
to the Cretaceous of New Jersey. Backhuys
to Marek Wanat, M. A. Alsonso-Zar-
Publishers, Leiden.
azaga, R. T. Thomas, and an anonymous
. 2003. The fossil record of weevils and re-
reviewer for supplying additional char- lated beetle families. Acta zoologica craco-
acters for determining the systematic vienses 46(suppl.): 129-138.
placement of this fossil. Lyal, C. H. C. and L. M. Curran. 2003. More than
black and white: A new genus of nanophyine
seed predators of Dipterocarpaceae and a re-
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