Primitive New Ants in Cretaceous Amber from Myanmar, New Jersey

24 Pages·2005·1.21 MB·English

PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY
CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024
Number 3485, 23 pp., 11 figures, 5 tables July 25, 2005
Primitive New Ants in Cretaceous Amber from
Myanmar, New Jersey, and Canada
(Hymenoptera: Formicidae)
MICHAEL S. ENGEL1 AND DAVID A. GRIMALDI2
CONTENTS
Abstract ....................................................................... 2
Introduction .................................................................... 2
Systematic Paleontology ......................................................... 5
Family Formicidae Latreille .................................................... 5
Subfamily †Sphecomyrminae Wilson and Brown ............................... 5
†Sphecomyrmodes, new genus ............................................. 5
Genus †Sphecomyrma Wilson and Brown ................................... 7
Genus †Haidomyrmex Dlussky ............................................ 11
Subfamily †Brownimeciinae Bolton ......................................... 12
Genus †Brownimecia Grimaldi, Agosti, and Carpenter ....................... 12
Subfamily Incertae Sedis ................................................... 13
†Myanmyrma, new genus ................................................ 14
Subfamily Aneuretinae? Emery ............................................. 17
†Cananeuretus, new genus ............................................... 17
Acknowledgments ............................................................. 20
References .................................................................... 20
Appendix ..................................................................... 22
1DivisionofInvertebrateZoology,AmericanMuseumofNaturalHistory;DivisionofEntomology,NaturalHistory
Museum, and Department of Ecology and Evolutionary Biology, Snow Hall, 1460 Jayhawk Boulevard, University
of Kansas,Lawrence,Kansas66045–7523 ([email protected]).
2DivisionofInvertebrateZoology(Entomology),AmericanMuseumof NaturalHistory([email protected]).
CopyrightqAmericanMuseumofNaturalHistory2005 ISSN0003-0082
2 AMERICAN MUSEUM NOVITATES NO. 3485
ABSTRACT
Newinformationisprovidedontheoldestfossilants(Formicidae),includingthedescription
of a new species of †Sphecomyrma (†Sphecomyrminae), a new genus of sphecomyrmines, a
new genus of apparent myrmeciines, and a new genus of apparent aneuretines. New material
from New Jersey amber (Turonian) includes workers of †Sphecomyrma freyi Wilson and
Brown preserved together in the same piece of amber, a worker of an unidentifiable †Sphe-
comyrma species, and a worker of †Brownimecia clavata Grimaldi, Agosti, and Carpenter
(†Brownimeciinae). A new species of †Sphecomyrma in New Jersey amber is described and
figuredfromaworkeras†S.mesaki,newspecies.TwoworkerspecimensinCampanianamber
from Canada are described, one of which is described as †Cananeuretus occidentalis, new
genus and species, and is tentatively placed in Aneuretinae. From Burmese amber (Albian-
Cenomanian)aretheoldest,definitiveants,alongwithonesinamberfromCharente-Maritime
ofFrance(approximatelycontemporaneousinage).Anewgenusandspecies,alliedto†Sphe-
comyrma, is described from these deposits as †Sphecomyrmodes orientalis, along with a
remarkable new ‘‘poneroid’’, †Myanmyrma gracilis, new genus and species (Myrmeciinae?).
A key to the speciesof†Sphecomyrma isprovided,theclassificationofantssummarized,and
the Cretaceous records of Formicidae briefly outlined.
INTRODUCTION myrma freyi Wilson and Brown, in New Jer-
sey amber. Since 1985, ants have been re-
Ants can truly be said to shape the terres-
ported in Cretaceous amber from Siberia,
trial world. Of the 11,833 species of Formi-
France, Canada, Burma, and additional new
cidae3, many have a profound impact on nat-
specimensandtaxainNewJerseyamber(re-
ural and manmade ecosystems, which is
viewed in Grimaldi et al., 1997, with addi-
madepossiblebytheireusociality,frequently
tionsbyDlussky,1999;GrimaldiandAgosti,
large colony sizes, and abundance. There is
2000a;Grimaldietal.,2002;Neletal.,2004:
scarcely a place outside of the polar regions
vide appendix 1). Here we report important
where one cannot find these insects or their
newspecimensofdescribedanttaxarecently
effects. Ants are among the most common
discoveredinNewJerseyamber,newspecies
and diverse kind of insect in various Ceno-
of †sphecomyrmines in both NewJerseyand
zoic deposits, and are particularly well
Burmese amber, as well as three new genera
knowninthefossilizedfaunasofDominican,
in Burmese and Canadian ambers (e.g., figs.
Sicilian, and Baltic ambers (Rasnitsyn and
1–3). While it is well established that New
Kulicka, 1990; Skalski and Veggiani, 1990;
Jersey amber is of Turonian age (Grimaldiet
Wilson, 1985a), as are the less spectacularly
al., 2000) and that Canadian amber is Cam-
preserved compressions from Lagersta¨tte
panian (Borkent, 1995), the dating of Bur-
such as Florissant (Carpenter, 1930), Green
River (Dlussky and Rasnitsyn, 2003), and mese amber has been contentious. Formerly
other Tertiary localities throughout the believed to be of Tertiary age, recent work
world. Although Formicidae came into their has demonstrated that the Burmese deposit
own during the Cenozoic, in the Mesozoic dates from the mid-Cretaceous (e.g., Zheri-
and Early Tertiary (Paleocene) formicids khin and Ross, 2000; Grimaldi et al., 2002;
were rare, and their earliest evolution has CruickshankandKo,2003).Thus,thosetaxa
been gradually unveiledwitheachnewfossil in Burmese amber (Albian-Cenomanian) are
discovery (e.g., Wilson et al., 1967; Wilson, among the current oldest records of ants
1985b; Grimaldi et al., 1997; Grimaldi and along with ants in amber of approximately
Agosti, 2000a;DlusskyandRasnitsyn,2003; contemporaneous age from Charente-Mari-
Dlussky et al., 2004; Nel et al., 2004). time, France (Nel et al., 2004), being at least
Until 1985, the only true formicid known 8–10 million years older than previous re-
from the Cretaceous Period was †Spheco- cords of the family.
In keeping with myrmecological tradition
and literature, we generally use terminology
3Species total accurate as of 17 June 2005 (vide
www.antbase.org). for morphological structures (e.g., antennal
2005 ENGEL AND GRIMALDI: CRETACEOUS ANTS 3
Figs. 1–3. Three Cretaceous amber ants. 1. †Myanmyrma gracilis, new genus and species (AMNH
Bu-014) in Burmese amber. 2. †Cananeuretus occidentalis, new genus and species (TMP 8.89.7) in
Canadian amber. 3. †Sphecomyrmodes orientalis, new genus and species (AMNH Bu-351)inBurmese
amber.
parts) as outlined by Ho¨lldobler and Wilson classification,herein,notinginvariousplaces
(1990)andBolton(1994);however,forbody where we believe it might eventually be
regions we have used head, mesosoma (5 modified. Material considered herein is de-
alitrunk),andmetasoma(5petiole1gaster), posited in the Amber Collection, Division of
as is standard in apocritan Hymenoptera. Invertebrate Zoology, American Museum of
Throughout,‘‘headlength’’ismeasuredfrom Natural History, New York (AMNH); the
the apex of the vertex to the anterior border Department of Palaeontology of the Natural
of the clypeus. The higher classification of History Museum, London (NHML); and
the ants has recently undergone a major re- Royal Tyrell Museum of Palaeontology,
arrangement owing to the work of Bolton Drumheller, Canada (TMP). Specimens in
(2003) (summarized with minor modifica- the AMNH collection were embedded in ep-
tions in table 1). We have employed that oxy for preparation and study, using the pro-
4 AMERICAN MUSEUM NOVITATES NO. 3485
TABLE1
Hierarchical SupragenericClassificationof the Ants (Formicidae)and AntlikeWasps (Armaniidae)
(modified from Bolton, 2003)a
2005 ENGEL AND GRIMALDI: CRETACEOUS ANTS 5
cedure outlined by Nascimbene and Silver- (perhaps paraphyletic?) to Formicidae (vide
stein (2000). table 1 and appendix 1).
Itisinterestingtonotethatmanyprimitive
SYSTEMATIC PALEONTOLOGY ants have clypeal spicules with rounded api-
ces (e.g., †Sphecomyrmodes, †Myanmyrma;
FAMILY FORMICIDAE LATREILLE Amblyoponinae). Apomyrma has similar
DIAGNOSIS: Head prognathous; dorsal rim spicules, but these are located on the labrum
of torulus often tuberculate or concealed un- ratherthanalongtheanteriorclypealmargin.
der vertical lamella of frons; antenna genic- The significance of this trait is as of yet un-
ulate. Primitively with anterior margin of clear (e.g., a ground-plan feature with nu-
clypeus spiculate (apomorphically lost in merous, apomorphic losses; or functional
many modern lineages: vide infra).Infrabuc- convergence).
cal sac present between labium and hypo-
pharynx. Pronotum with posterodorsal mar- SUBFAMILY †SPHECOMYRMINAE
ginweaklyconcave;posterolateralapextrun- WILSON AND BROWN
cate anterior to tegula. Metapleural gland
†Sphecomyrmodes, new genus
present in females, opening above metacoxa
(rarely absent);meso-andmetacoxaecontig- TYPE SPECIES: †Sphecomyrmodes oriental-
uous; inner metatibial spur modified as cal- is, new species.
car. Hind wing typically without jugal lobe DIAGNOSIS: Distinguished from all other
(presenceof thelobeisplesiomorphicwithin species of the tribe Sphecomyrmini by the
the family and likely part of the familial minute, peglike denticles running along the
ground plan). Metasoma petiolate; first me- entirety of the anterior margin of the clypeus
tasomal segment forming truenode(strongly and from †Sphecomyrma by the absence of
constricted anteriorly and posteriorly); first a medial extension or process on the clypeal
metasomal sternum separated from second margin.
metasomal sternum by deep constriction. ETYMOLOGY: The new genus-group name
Morphologicallydistinct,sterileworkercaste is a combination of †Sphecomyrma, type ge-
typically present4 (i.e., advanced eusocial); nus of the subfamily, and the suffix–odes,
reproductives typically macropterous, work- meaning ‘‘with the form of’’. The name is
ers apterous. Workers with pronotum fused masculine.
to mesothorax (a freely articulating prono-
tum, present in some species, is plesio- †Sphecomyrmodes orientalis, new species
morphic and undoubtedly part of the formi- Figures 3–4
cid ground plan), remaining segments typi-
cally fused. Species advanced eusocial. DIAGNOSIS: As for the genus (vide supra).
COMMENTS: The ants, currently including DESCRIPTION: Head. Relatively large,
11,833 species (Bolton, 1995; www. height of head slightly less than length of
antbase.org)haveacosmopolitandistribution alitrunk.Lengthofhead1.23mm(withman-
and are among the most recognizable of all dibles closed). No apparent microsculpture
insects. Numerous species exist in Cenozoic on cuticle of head. Clypeus setose; setae of
deposits around the world and are relatively moderate length and widely separated. Man-
commonly encountered. Species of Creta- dible simple, with only two teeth; outer sur-
ceous formicids, which are very rare, are face with numerous, widely scattered, fine
briefly outlined in appendix 1. setae. Antenna of moderate length, with
Bolton (2003) considered the antlike scape short, funicular article I (pedicel)
wasps of the Cretaceous family Armaniidae shortest antennal article, funicular article II
to represent the basalmost subfamily of the the longest article of funiculus. Lengths of
ants. We have, however, retained armaniids antennalarticles(inmm):scape0.23,pedicel
at the family rank and as the sister group (funicular article [fa] I) 0.13, faII 0.32, faIII
0.15, faIV 0.15, faV 0.15, faVI 0.15, faVII
0.17, faVIII 0.17, faIX 0.17, faX 0.17, faXI
4Someinquilineshaveapomorphicallylostthework-
ercaste. 0.27. Mesosoma. Mesosomal length 1.33
6 AMERICAN MUSEUM NOVITATES NO. 3485
Fig. 4. Holotype workerof †Sphecomyrmodesorientalis, newgenusandspecies(AMNHBu-351);
general habitus, sting, clypeal margin and mandibles, and antenna.
mm;withoutapparentmicrosculpturing,with lycurvedinwardattheirextremeapices(vis-
scattered fine, short setae on all visible sur- ible on left foreleg). Pairs of stiff setae on
faces, those on propodeum about twice as ventral surface of protarsomeres: tarsomeres
long as other setae. Coxae large, slightly in- I-III with three pairs, IV with two small
flated, ventrally setose, setae numerous and pairs. Pretarsal claw with minute subapical
fine. Legs moderate length. Foreleg with tar- tooth. Metasoma. Attachment of petiole to
somere I distinctly longer than combined propodeum not particularly thick; thickness
lengths of more distal tarsomeres; tarsomere (measured in lateral view) of anterior end of
I with ‘‘antennal cleaner’’ (strigil) a velvety petiolar peduncle 0.33 greatestdepthofpro-
notchonventralmarginofproximalend;cal- podeum. Petiolelength0.38mm,height0.37
car present, length slightly longer thangreat- mm. Preserved portion of gaster 1.73 mm in
est width of profemur, ventral margin with length. Integument without apparent micros-
row of fine teeth and (apically) setae. Patch culpturing, with scattered, fine setae. Distal-
of dense, elongate setae opposite strigil on most metasomal segments torn apart, al-
profemur; inner posterior surface of protibial though sting bulb and sting well preserved
apex with threestout,spinelikesetaeminute- beneath metasoma (fig. 4).
2005 ENGEL AND GRIMALDI: CRETACEOUS ANTS 7
TYPE MATERIAL: Holotype. AMNH Bu- †Sphecomyrma mesaki, new species
351, an incompletely preserved worker in a Figure 5
piece of reddish-orange amber, from Myan-
mar. Collected in Kachin state,Tanaivillage, DIAGNOSIS: Distinguished from all other
on Ledo Road, 105 km NW Myitkyna, via species of the genus by the median portion
Leeward Capital Corp., 1999. of the clypeus having a long ventral lobe,
ETYMOLOGY: The specific epithet is the length of the clypeus through the lobe is
Latin word orientalis, meaning ‘‘oftheeast’’ 0.463 the greatest width of clypeus; clypeus
and is a reference to this being the first spe- setose;and scapeveryshort(1.23thelength
ciesofthetribe†Sphecomyrmini(sensuBol- of longest funicular article). The species can
ton, 2003) recorded from Myanmar. be further distinguished from †S. freyi (the
otherspeciesofthegenusinNewJerseyam-
ber) by broad, shallow scrobes at base of an-
Genus †Sphecomyrma Wilson and Brown
tennae;aneyethatisapproximately1/3larg-
†Sphecomyrma Wilson and Brown, In Wilson et erand oval(vs.almostperfectlyroundin†S.
al., 1967: 8. Type species:†Sphecomyrmafreyi freyi); and a large head (length of head/
Wilson and Brown, 1967, monobasic and orig- length of mesosoma 5 0.83, vs. 0.65 in †S.
inal designation. freyi).
DESCRIPTION: Petiole and gaster not pre-
DIAGNOSIS: Scape short; funiculus long
served, so only head, mesosoma, and legs
and filiform, about four times length of
preserved. Head. Large, length of head
scape; promesothoracic suture complete and
slightly less than length of alitrunk. Length
well developed; trochantellus absent; petiole
of head 2.20 mm (with mandibles closed);
with distinct, domed node widely separated
width of head 1.95 mm; length of eye 0.66
frompropodeumandremainderofmetasoma
mm. No microsculpture on cuticle of head.
by deep constrictions; cuticle without sculp-
Vertex with fine,sparsepilosity,setaeca.0.2
turing, superficial microscopic relief, with
mm long. Ocelli present, median ocellus sit-
scattered and sparse setae.
uated just above dorsal tangent of compound
COMMENTS: The genus, which is defined
eyes. Face bare. Bases of antennae situated
largely by plesiomorphies, is doubtfully
in shallow, broad scrobes; length of scrobe
monophyletic. It contains three species:
about equal to length of scape and articulat-
†Sphecomyrma canadensis Wilson in Cana-
ing base. Eyes well developed, bare, situated
dian amber, and †S. freyi Wilson and Brown
well above bases of antennae; gena deep.
andanewspeciesinNewJerseyamber(vide
Lateral portions of clypeus quadrate; median
infra). In addition, we provide information
portion distended into long ventral lobe that
from newly identified material of †S. freyi.
extends to ventral margin of closed right
mandible. Clypeus setose, except on middle
Key to Species of †Sphecomyrma
part. Mandibles simple, with only two teeth.
(based on the worker caste)
Antennae of moderate length, with scape
short,funiculararticleI(pedicel)shortestan-
1. Anterior margin of clypeus with short, broad
extension, surface with two, long setae at tennal article, funicular article II the longest
most; compound eye round .......... 2 article of funiculus. Lengths of antennal ar-
— Anteriormargin ofclypeuswithlong,medial ticles (in mm): scape 0.53, pedicel(funicular
lobe (fig. 5), surface with numerous, long article [fa] I) 0.20, faII 0.43, faIII 0.35, faIV
setae;compoundeyeoval[NewJerseyam- 0.30, faV 0.23, faVI 0.23, faVII 0.30, faVIII
ber] .............................. 0.22, faIX 0.26, faX 0.30, faXI 0.33. Meso-
.... †S. mesaki Engel and Grimaldi, n.sp.
soma. Mesosomal length 2.66 mm; without
2. Third antennal article slightly more than
microsculpturing, except at posterolateral
twiceaslongassecondarticle[NewJersey
margin of promesonotal suture, where eight
amber] ...........................
fine grooves occur. Dome of promesonotum
........... †S. freyi Wilson and Brown
— Thirdantennalarticleaboutaslongassecond setose; several fine setae on dorsalsurfaceof
article [Canadian amber] ............. metanotum and propodeum. Coxae large, in-
................ †S. canadensis Wilson flated,ventrallysetose.Attachmentofpetiole
8 AMERICAN MUSEUM NOVITATES NO. 3485
Fig. 5. Holotype worker of †Sphecomyrma mesaki, new species (AMNH NJ-1023); lateral habitus
and facial view.
2005 ENGEL AND GRIMALDI: CRETACEOUS ANTS 9
to propodeum not particularly thick; thick- bedded and trimmed to 14 3 15 3 4 mm.
ness (measured in lateral view) of anterior The piece contains two workers of †S. freyi.
end of petiolar peduncle 0.3x greatest depth DESCRIPTIVE NOTES: Both workers are
of propodeum. Metapleural gland opening largely but not completely preserved. Spec-
(MGO) and MG bulla obvious, situated on imen A has the frontal half of the headmiss-
posterolateral part of propodeum just above ing; mostof theantennaispresentexceptfor
metacoxa. MGO small, with groove running bases of the scapes; the entirety of the re-
between it and extended almost to vental mainder of the body is preserved and the
marginofpropodeum.Legsmoderatelength. sting appears largely or fullyextruded.Spec-
Foreleg with tarsomere I slightly longer than imen B has the dorsal and apical part of the
combined length of more distal tarsomeres; gaster missing, as well as portions of the
tarsomere I with ‘‘antennal cleaner’’ (strigil) right hind leg; the anterior third of the head
a velvety notch on ventral margin of proxi- is obscured by Schimmel and a bubble.
mal end; calcar present, length slightly lon- Measurements of body: Width of head
gerthangreatestwidthoffemur,ventralmar- (specimen B), 1.03 mm; length of head (B,
gin with row of fine teeth and (apically) approximate), 1.20 mm; length of mesosoma
hairs. Stiff setae on ventral surface of pro- 1.39mm(B),1.40mm(A);lengthofpetiole
tarsomeres: tarsomere I with 7 pairs, II with 0.29 mm (B), 0.33 mm (A); length of gaster
3 pairs, III with 3 small pairs, IV with 2 (A) 1.72 mm; length of extruded portion of
small pairs. Pretarsal claw with subapical sting (A), 0.33 mm. Measurements of anten-
tooth. Metasoma not preserved. nal articles (as measured for right antenna in
TYPE MATERIAL: Holotype. AMNH NJ- A, left antenna in B) presented in table 2.
1023, an incompletely preserved worker in a Measurements of leg segmentation (as mea-
piece of amber barely larger than the ant, sured on specimen A) presented in table 3.
from Sayreville, New Jersey (Middlesex COMMENTS: The discovery of this piece of
Co.), White Oaks outcrop, coll. Bob Mesak amber is highly significant and addresses
(fig. 5). The amber is an irregularly shaped questions of the social behavior of primitive
drop, 7 3 5 3 4 mm, made of clear yellow antslike†Sphecomyrma.AsreviewedinGri-
amber. Portions of some appendages are maldi et al. (1997), Dlussky (1987, 1988),
breached at the surface, and the petiole and and Poinar et al. (1999) questioned whether
gaster were similarly lost at the surface. †Sphecomyrma was a true ant since it had
Sinceverylittleamberexistsbetweentheant such a short scape [but see response to Poin-
and surface of the amber piece, no trimming ar et al. (1999) by Grimaldi and Agosti
or polishing was possible. Still, details (2000b)]. With such a short scape, Dlussky
through the rough surface are highly visible argued that it would be impossible for
by immersing the piece in glycerine. †Sphecomyrma to antennate, and therefore it
ETYMOLOGY: The specific epithet is a pat- was considered highly unlikely for †Sphe-
ronymic for Bob Mesak, who collected and comyrmatohavebeensocial.Amongtheap-
donated this valuable specimen to the proximately1700fossiliferouspiecesofNew
AMNH. Jersey amber in the AMNH collection thus
far, four pieces contain worker or malesphe-
†Sphecomyrma freyi Wilson and Brown comyrmine ants. These ants are (and proba-
Figure 6 blyoriginallywere)exceedinglyrare,andthe
probability that two workers would be pre-
†Sphecomyrma freyi Wilson and Brown, In Wil- served in one piece by chance alone is ex-
son et al., 1967: 8. Grimaldi et al., 1997: 12
tremely remote. It is most parsimonious to
(redescriptionofsomefeatures,newspecimens,
explain the occurrence of two workers in the
neotype).
same piece as a result of social behavior.
MATERIAL: AMNH NJ-943, in amberfrom
New Jersey: Middlesex Co., Sayreville, †Sphecomyrma sp.
White Oaks outcrop, collectedbyKeithLuz-
zi (fig. 6). The piece is transparent yellow, MATERIAL: AMNH NJ-942, a male in am-
originally much larger than now; was em- ber from New Jersey: Middlesex Co., Say-
10 AMERICAN MUSEUM NOVITATES NO. 3485
Fig. 6. Two workers of †Sphecomyrma freyi Wilson and Brown preserved in a single pieceofNew
Jersey amber (AMNH NJ-943).
reville,WhiteOaksoutcrop.Collectedbythe COMMENTS: Venation and other details of
late Steve Swolensky. Specimen is in a clear this specimen are indistinguishable from
yellow piece of amber 5 3 7 mm, embedded AMNH NJ-242, described andfiguredbyGri-
in epoxy and trimmed to 1.5 mm thickness maldi et al. (1997) as †Sphecomyrma? sp.
for a full lateral view of the ant. Measurements:Lengthofhindwing(forewing