| This is the CEC archive of Psyche through 2000. Psyche is now published by Hindawi Publishing. |
The First Mesozoic Ants, with the Description of a New Subfamily.
Psyche 74(1):1-19, 1967.
This article at Hindawi Publishing: https://doi.org/10.1155/1967/89604
CEC's scan of this article: http://psyche.entclub.org/pdf/74/74-001.pdf, 3700K
This landing page: http://psyche.entclub.org/74/74-001.html
The following unprocessed text is extracted automatically from the PDF file, and is likely to be both incomplete and full of errors. Please consult the PDF file for the complete article.
Sfhecomyrma freyl, worker no. 1, holotype.
================================================================================
================================================================================
PSYCHE
Vol. 74 March, 1967 No. I
THE FIRST MESOZOIC ANTS,
WITH THE DESCRIPTION OF A NEW SUBFAMILY
BY
EDWARD 0. WILSON,'~ FRANK M. CARPENTER,^ and WILLIAM L. BROWN, JR.~
INTRODUCTION
Our knowledge of the fossil record of the ants, and with it the fossil record of the social insects generally, has previously extended back only to the Eocene Epoch (Carpenter, 1929, 1930). In the Baltic amber and Florissant shales of Oligocene age, and in the Sicilian amber of Miocene age, there exists a diverse array of ant tribes and genera, many of which still survive today (Emery, 1891 ; Wheeler, I 9 I 4 ; Carpenter, I 930). The diversity of this early Cenozoic ant fauna has long prompted enton~ologists to look to the Cretaceous for fossils that might link the ants to the non-social aculeate wasps and thereby provide a concrete clue concerning the time and circumstances of the origin of social life in ants; but until now no fossils of ants or any other social insects of Cretaceous age have come to light (Bequaert and Carpenter, 1941 ; Emerson, 1965) and we have not even had any solid evidence for the existence of Hymenoptera Aculeata before the Tertiary. There does exist one Upper Cretaceous fossil of possible significance to aculeate and
thus to ant evolution. This is the hymenopterous forewing from Siberia described by Sharov (1957) as Cretavus sibiricus, and placed by him in a new family Cretavidae under the suborder Aculeata. As Sharov notes, the wing venation of Cretavus does resemble that of the bethyloid (or scolioid) wasp family Plumariidae, a group that has been mentioned in connection with formicid origins. The Cretavus wing is also similar to that of such primitive Tiphiidae as Anthobosca (see figures, discussion and refer- ences in Brown and Nutting, 1950). But the difficulty with this fossil is that we have only the wing, and there is no guarantee that Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts.
'Department of Entomology, Cornell University, Ithaca, New York, and Museum of Comparative Zoology, Harvard University.
================================================================================
================================================================================
19671 Wilson, Carpenter, Brouln - Mesozoic Ants 3 the evolution of venational and body traits proceeded concordantly before, during or after the transition from parasitic to aculeate Hymenoptera. In other words, we do not know from the present evidence whether the diagnostic body characters of the whole insect Cretavus would place it in the Aculeata or not. The reason for the apparent absence of social insects before the Tertiary may be due at least in part to the general scarcity of Creta- ceous insects. The most notable relevant Cretaceous deposit, the Cedar Lake amber from Manitoba studied by Carpenter and his associates ( 1934) , contains moderate numbers of insects, and some are Hymenoptera, but these include no ants or aculeates of any kind. Two explanations seem possible: either the Cedar Lake amber, which has not been precisely dated within the Cretaceous,^ originates from an early part of the period, prior to the origin of the aculeates, or else the early aculeates were too large to be enclosed in the small amber pieces that characterize the deposit. Amber has been found in Cretaceous deposits along the Arctic coastal plain of Alaska (Langenheim Smiley and Gray, 1960) but very few insects are included and no aculeates have been reported. For many years numerous pieces of amber have been recovered from sediments exposed along the coastal plain of Maryland and Ne~v Jersey, as well as on Staten Island and Nantucket. These pieces have apparently been derived from at least two formations, the Raritan and the Magothy, both of which are referable to the lower part of the Upper Cretaceous. The first published account of this amber appeared nearly 150 years ago (Troost, 1821) but, in spite of frequent observations on the occurrence of the amber almost no records of insect inclusions have been published. Indeed, the only account of an inclusion was that in Troost's original report on the amber ( I 82 I ) , which contained a "description of a variety of amber and of a fossil substance supposed to be the nest of an in~ect".~ '~angenheim, Smiley and Gray (1960, p. 135) refer to the Cedar Lake amber as of "presumed Late Cretaceous Age". However, Dr. Langenheim informed me subsequently (pers. corn., 1964) that he had no knowledge of evidence dating the amber at any specific level within the Cretaceous. [F. M. C.]
"It is of interest to note that at the first meeting of the Cambridge Entomo- logical Club, January 4, 1874, Professor Hermann Hagen presented an account of this specimen, concluding that it was a group of galls on a twig (Hagen, 1874). No formal description was ever published. EXPLANATION CF PLATE 2
Sphromvma frfj~i~ worker no. 2, paratype. The head is viewed obliquely from below and in front.
================================================================================
================================================================================
19671 Wilson, Carpenter, Brown - Afesozoic Ants 5 In 1966 311-. and IIrs. Edm~md Fsej-, of Alauntainside, New Jersq~) while collecting n~inesalogical spcci~nens in the %lagothy es- posuie at the beach blufls, Clifhood, New Jessey, found a relatively large piece of amber containing several insects. The amber, when discovered, was i~nbedded in the clay bank. Professor Donald Baisd of Princeton University reported the find to one of US (F.31.C.) and event~dly 81r. David Stager of the Newark 3luseum kindly arranged for the loan of the specimen by hlr. and hlrs. Fi-ey. All who are interested in insect evo1ution are indebted to >Is, and Mrs. Frey for their alertness in discovering the amber and especially for their full cooperation in allowing the amber inclusions to be prepared and studied. Important as these insects are, the knowledge that insects actually OCCLU in this Cretaceous amber is of even greater significance. In all probability much of the amber psevious1y co1- lected contained insects that were simply not detected. Effai-ts are now being made to examine earlier collections of the amber fso~n the &lagothy and Rasitan Faimations and also to obtain new material by collecting at the several exposures of these two beds. The Magathy Formation, in which this fossiliferous piece of amber was found, has exposures in llaryland, Delaware, New Jersey) Long Island and other islands of the southern New England coast. It consists mainly of light-colored sands, with layers of gray or dark brown clays. Leaf impressions, lignite and the amber occur in the clay beds, The 3lagothjr Formation has been referred consistently to the lower part of the Upper Cretaceous (Turonian-Coniacian stages). Resting on the Raritan, which lies at the bottom of the Uppel- Cretaceous, it was presumably deposited not long after mid-Cretaceous times, about 100 nil lion ears ago. The plants in the XIagothy For- mation have been studied chiefly by Berry ( 19~4, 1905) 1906, 1907) but his generic determinations are not generally accepted by botanists at the present time. &fore recently, pollen and spores in the hfagothy have been investigated by Groot, Penny and Groot (1961) and by Stover ( I 964). Certain cones and twigs in the hfagothy clays almost cestainly belong to Sequoia (l3e1-ry, 1905 ; Hollick, 1905) or se- lated genera. There is good evidence that such trees produced most of the amber now found in the 3lagothy. KnowIton (1896) reported that a lignitic log about 4 feet long, which was found in the Potomac Formation (below the Alagothy, in the Lower Creta- ceous) and which possessed a woody stsuc ture characteristic of Sequoia, contained several pieces of amber. Very recently (1967) pers. com.) Dr. Jean Langenheim, of the University of California at
================================================================================
6 Psjjc h c
[March
Santa Ci-uz, has informed one of us (F.3I.C'j that she has tenta- tively concluded from her inii-ared studies on resins and a111be1-s that most of the Atlantic Coastal Plain amber (including that from Cliff- wood beach) was probably produced by taxodiaceous trees, very likely Scquoidendron or ~letaseq~~oia.~
Among the insects in the amber which >Ire and 311-s. Frej- col- lected at Cliffwood beach are two unmistakable worker ants. These speci~nens have fulfilled nmly of our fondest speculations about what a JIesozoic ant might be like, and thus they demonsti-ate to us anew the predictive power of ph~~logenetic reasoning (See Plate 4.). Jf7e fii-st present their formal description as a new subfamily, genus, and species and then pro~ride a discussion of theii- phylogenetic significance. 7 7
1 he other insects in the amber, all Diptesa, will be turned over to appl-opi-iate specialists for subsequent study and desci-iption. Fa~nily Formicidae
Sphecomyrminae JVilson and Brown, new subfamily Diagnosis (worker) : Slandibles peculial-ly wasp-like) short, nar- row, curvilinear, bidentate. Antennae 12-segmented, with a ~7ell- formed but relatively short scape and an exceptionally long (for an ant), almost filiform funic~~lus, The second funicular segment is longer than any other funicular segment) a rather unusual feature apparently ,shared with hTothonzyr?ncci~ (some higher ants have a long second funicular fusion segment, e.g., workers and females of Orectognathus and males of most Tetramoriunz and allied genera). Compound eyes large) convex, placed near the middle of the sides of the head. Ocelli present.
Body form that of a very primitive formicid. Alitrunk (=thorax + propodeum) slender, in form vei-y much like that of Alethocha ??zahyana (Fig. 3 j) M. stygia, and some other species of that genus (Reid, 1941 : figs. 26-27 ; Pagden, 1949). Sutures between pro- and ~nesothorax, and between meso- and metathoi-ax, both complete) pos- sibly movable. 31esonotom long and slender, with distinct, convex scutum and sc~~tellun~ separated by a rather distinct axillary re- gion. AIetathosacic spiracles present, situated just below the limits of the scutellum on each side near its posterior margin, as in 5We are indebted to Mr. James Doyle of Harvard University for his assistance with this paleobotanical literature.
================================================================================
Figure I.
Drawing of Sphecomyrma freyi, worker no. I. Only struc-
tures that could be clearly seen were drawn. Thus the figure is a direct rendition and not a reconstruction, although the appendages have been turned to more life-like positions.
================================================================================
8 Psyche [March
Meihocha Metanot~im a deeply impressed transverse groove between scutellum and rounded propodeum. $!Ietapleural gland bulla and meatus present and well-developed (though it is difficult to be ab- solutely certain of this in amber specimens). Petiole with a distinct, raised node with strongly rounded summit) strongly separated from propodeum and first segment of gaster by deep constsictions. Gaster without a constsiction behind first segment; strong exsertile sting present. Legs long and slender, the last two pairs having 2 spurs at the apex of each tibia. Tarsal claws each with a median tooth. Type and only known genus is the following: Sphecomyrma IVilson and Brown) new genus FVorker: JVith the characters of the subfamily. Head capsule un- exceptional, more or less like that of a primitive formicine, such as ProZasius, Notoncus, 01- even PrenoZepis. Clypeus broad, simply formed) convex) with broadly rounded free margin. Antennae in- serted moderately far apai-t and well foi-wai-d on the head capsule, their sockets close to the posterior masgin of the clypeus. Compound eyes oblate circular in outline, large and convex, each with more than 100 omniatidia. Ocelli well-developed. Antenna1 segmentation and proportions unique, as shown in Figure 2A. Alitrunk with rounded humeri. Propodeal spiracle high up, its opening elongate. Petiolar segment with a distinct node in the form of a narrowly-rounded dome, briefly pedunculate in front and behind, much narrower than the succeeding (gastric) segment) and separated from it by a broad and deep constriction. First gastric segment with an anteroventral process like that found in L$fyr7~~ecia as well as many ponerine genera. Sting exserted, strong and acute. Integument appearing relatively thin, not boldly sculptused any- where; sculpture fine and superficial) body surface opaque to sub- opaque.
Queen and male unknown.
Type and only known species: Spheco7nyr?na freyi, described below. Sphecomyrma freyi Wilson and Brown, new species Plates 1-4; Figures I, 2
Holotype and paratype workers: the characters cited in the sub- family diagnosis, and particularly the form of the mandibles) an- tennae and mesonotum, readily distinguish this species from all other known ant species, living or fossil.
================================================================================
19671
Wilson, Carpenter, Brown - iklesozoic Ants Figure 2. Drawings of various body parts of S~hrcomyrma frcyi. A, head of worker no. 2, view from below and in front. B, left mandible of worker no. 2, seen in fuller frontal view than in -4 so as to reveal the truncated shape of the inner tooth. C, pretarsus of left hind leg of worker no. 1.
D, propodeurn and metapleural region of worker no. 1. E, oblique dorsal view of body of worker no. 20
================================================================================
10 Psyche [March
The two workers are very similar in most characters, but differ markedly in size.
Both are roughly what would be called "medium- sized" ants.
Some exact measurements could be taken, to the nearest 0.01 mm, and these are given in millimeters as follows: Specimen I.
Head width not measured; head length along mid- line 0.98; maximum length of right eye 0.32. Segments of left an- tenna (numbered I through XII) from insertion outward: I (scape) 0.60, 11 0.16, 111 0.34, Iv 0.21, v 0.21, VI 0.21, VII 0.21, VIII 0.21, IX 0.21, X 0.21, XI 0.21, XI1 0.26. (Holotype). Specimen 2.
Head width taken just anterior to the compound eyes, 1.03; head length not measured. Segments of right antenna (numbered I through XII) from insertion outward: I (scape) 0.68, 11 0.18, 111 0.40, Iv 0.27, v 0.27, VI 0.26, VII 0.26, VIII 0.26, IX 0.24, X 0.23, XI 0.23, XI1 0.31. (Paratype). The details of morphology, including pilosity, are evident in the figures. Pubescence consists of scattered, short (about 0.01 mm long), appressed hairs.
Both specimens are uniform light brown in color, but this means little in view of the passage of 100 million years. Holotype: worker, labelled FI, shown in photograph, Plate I ; paratype: worker, labelled F2, shown in photograph, Plate 3. Both specimens were collected in a single piece of amber (now in sep-
rate pieces) in clay, Cliffwood Beach, on Raritan Bay, New Jersey, by Mr. and Mrs. Edmund Frey. The specimens are in the collection of Mr. and Airs. Frey, Mountainside, New Jersey. Sphecomyrma freyi presents a mosaic of wasp-like and ant-like character states. Moreover, most of the ant-like features are, as well as we can judge the matter, primitive with respect to the other known Formicidae. Our assignments of various character states are given in Table I. An examination of this arrangement will show that Sphecomyrma is truly intermediate between the primitive ants Figure 3. Alitrunk of Methocha malayana female in side view. (Re- drawn after Pagden, 1949).
================================================================================
19671 Wilson, Carpenter, Brown - Mesozoic Ants I I and the aculeate wasps.
However, we feel that the metapleural
gland, the nodiform, posteriorly constricted petiole, and the generally ant-like overall habitus place this species among the primitive ants rather than the wasps. However, if we are mistaken about the pi-es- ence of the metapleural gland, it would be possible to consider Sphecom~rma as a wasp rather than an ant. Which of the aculeate wasp groups might have given rise to the Sphecomyrminae?
In Table 2 we present a scheme by Dr. Howard E. Evans, who has compared the Mesozoic ant with a wide range of modern aculeate families (fossil wasps are too scarce to be of much use). It can be seen that the Tiphiidae, and in particular the genus Methocha, come closest. (Methocha is impressively similar in de- tails of thoracic structure, as shown in Figure 3). But we agree with Evans that such a comparison must be treated very carefully. The modern aculeate wasps are specialized both morphologically and ecologically: for example, Methocha of several species are known to TABLE 1
Relationships of the Principal Character States of Sphecomyrma freyi
Aculeate Other primitive Both aculeate
wasps only ants only wasps and
primitive ants
Narrow bidentate
mandibles
_L
Well-formed
slender scapes
Long, filiform
funiculi
1
Large compound
eyes
Well-formed
ocelli
Broad, simple
clypeus
Reduced, apterous
thorax
Mesonotum with
separate, dis-
tinctly convex
scutum and
scutellum
Metapleural gland
Petiole with node
deeply constricted
front and rear
Gaster ovoid,
unconstricted
Extrusible sting
================================================================================
Psyche
[March
DORYLINAE &(
o r LEFTAN 1LLINAE
advanced (from 2-4 unknown
P@NERlN*E ponert; c stocks>
PSEUDOMYRMEClNAE
MYRMECIlNAE:
ant-like antennae
I~LIC soci'afitu
'Ì (i.e.,cither hone-
or diphyletic)
TlPHIlD ANCESTOR
Figure 4. Hypothetical cladogram of the subfamilies of ants (Formi- cidae), based on all available evidence including the analysis of Sphe- comyrma.
be parasitoids of tiger beetle larvae (Clausen, 1940: 298). There is now a greater need than ever to discover and to study in detail aculeate wasps of Cretaceous age.
The relationship of Sphecofnyrma freyi to the other ants is clearer. The body of Sphecomyrma resembles that of the primitive myrmecioid ants, notably the living Nothomyrmecia macrops of Australia, which we regard as the most generalized member of the primitive subfamily Myrmeciinae (Brown and Wilson, 1958), and the Eocene genera of Aneuretini, which are the undoubted ancestors of the other Dolichoderinae (Wilson et d, I 956). Previously we had considered that the Aneuretini might have been derived from the Myrmeciinae, because we considered the long mandibles of the Myrmeciinae as primitive and the short mandibles of the Aneuretini as derived. Now the discovery of short, wasp-like mandibles in Sphecomyrma has in- validated this postulate.
In Sphecomyrpna, then, we have what appears to be a good link between aculeate wasps and the myrmecioid complex of subfamilies,
================================================================================
Table 2. Degree of similarity of body parts of Sphecomyrma freyi with genera of various aculeate families. +"I, nearly identical, scored as 3. +"I", mostly similar, with minor differences, scored as 2. +, mostly dissimilar but with a few details matching, scored as 1. -, wholly dissimilar, scored as 0.
These genera include those
previously believed to fall closest to the primitive ants, as well as other, representative genera. Except for (The evaluation of the wasp familiits was the 0lig;cene Paraneuretus, all are represented by provided by Dr. Howard E. Evans.)
living species.
Mandibles
POMPILlDAE
Epi$ompilus $ + + +
SIEROLOMORPHIDAE
Sierolomorpha $2 +
RHOPALOCOMATIDAE
Rizopalosoma Q -
PLUMARIIDAE
Plumarius Q -
Plumarius $
-
MUTILLIDAE
Afterogyna $2 -
Apterogyna $ -
VESPIDAE
Gayrlla ? -
blaster $ -
THYNNIDAE
Aelurus $ -
Aelurus $ +
Diamma $ -
Diamma $ -
Rhagigaster $ ++
Rhagigaster $ + + +
TIPHIrDAE
Anthohosca ?
-
Anthobosca $ + + 4-
Glyptometopa 9 -
Methocha Q +++
FORMICIDAE
Amblyopone 9 -
Nothomyrmecia 9 +
Parancuretus 9 4- +
Clypeus
+
++
-
-
4-
-
++
+
++
-
++
+
++
+
++
++
++
-
++
++
+++
+++
Antenna
++
++
+
-
+
++
+
+
+
-
+
-
+
-
+å
-
+
-
++
++
++
4-4-
Ocelli
++
++
+
+
--
++
++
++
-
+ -1
++
++
-
++
+ +
++
++
-
++
-
Petiole
-
+
I-
-
-
i-+
++
++
+
-
-
+
+
-
+
--
-
-
-
+
+I-
++
Similarity to
Alitrunk Sphecomyrma
(Mesosoma) numerical score
================================================================================
14 Psyche [March
namely the Myrmeciinae, Pseudomyrmecinae, Dolichoderinae (in- cluding Aneuretini) and Formicinae. (See the arrangement of ant subfamilies into the "myrmecioid" and poneroid" complexes by Brown, 1954). Where does this leave the poneroid subfamilies in the scheme of things? Among the poneroids, including the Ponerinae, Dorylinae, Leptanillinae, and Myrmicinae, the most primitive group is certainly the Ponei-inae, and most particularly the ponei-ine tribe Amblyoponini. It is disconcerting to find that the ponerines are hardly closer to Sphecomyrma than they are to the primitive myi-me- cioids. There is no trace of the ponei-ine gastric constriction in the latter two groups. More significantly, the Amblyoponini have an incompletely constricted petiole (that is, the petiole is broadly attached posteriorly to the gaster), and they also have the constriction be- tween the first and second gastric segments. Sphecomyrma lacks the gastric constriction, but has the petiole strongly constricted behind. We have long considered the amblyoponine petiolar form as primitive among the ants, and it certainly resembles that of some tiphioids as much as or more than it does that of most other ants. One character that has never received any particular attention is the form of the amblyoponine male mandibles (Brown, 1960: figs. 8, 26) which is in fact now seen to be quite primitive. In the species
of Amblyoponini so far described, the mandibles are narrow and wasp-like, sometimes bidentate, and sometimes tapering to a single acute point (the latter condition is evidently derived) ; they close tightly against the convex free clypeal margin, as do those of most wasps. (The more elaborate worker-female mandibles of Amblyo- ponini are not too difficult to imagine as derived from the bidentate wasp-like form.) When considered together, the petiole and the male mandibles of Amblyoponini certainly strengthen the general impression that this tribe is very primitive, although it shows tenden- cies toward specialization for life in cryptic habtats. If the amblyoponine petiole is truly more primitive than the Sphecomyrvia petiole, then the split between myrmecioids and pone- roids must have come at a time when ants were still very wasp-like, and perhaps we should even consider the possibility that the diver- gence occurred before these groups had fully acquired their sociality. In the light of this last possibility, the metapleural glands assume a particular importance in our phylogenetic speculations. The fact that they are such complicated organs makes it unlikely that they were evolved independently in different ant lineages. If their func-
tion - at present unknown - is eventually shown to be primarily
================================================================================
19671 WilsonJ CarpenterJ Brown -iMesozoic Ants 1.5 social, then the hypothesis of a single origin of social life in ants would tend to be supported.
A cladogram outlining our present best guess at ant phylogeny is given in Figure 4.
Judging from the characteristics of the primitive ants and the tiphiid wasps as we know them now) we would reconstruct the aschetypal ant as follows:
Wosker -
hlandibles narrow, short, curved) bidentate) closing tight111 against clypeus.
3laxillai-y palpi 6-segmented) labial palpi 4-segmented. Antenna1 scapes shorter than in most ants) but a little longer and more slendrr than in most tiphiids.
Antenna1 funiculi long) slender) filiform) with I I segments. Compound eyes large, convex, oval or round) situated near middle of sides of head.
Ocelli well-developed.
Promesonotal suture con~plete) movable.
hlesonotum with scutum and scutellum separate and distinct. Alesonoto-~netanotal suture complete) possibly movable. Metapleui-a1 gland bulla and meatus present. Tibia1 spurs I, 2, 2.
Tarsal claws toothed.
Petiole consisting of a single segment, sessile in front) or nearly so) sessile and broadly joined to gaster behind (with little intervening constriction).
Gaster unconstricted.
Sting strong and functional.
Of these character states, Sphecomj~rrna agrees with all but No. 13 (petiole form) ; its status with regard to No. 2 (palpal segmenta-
tion) is actually unknown, but we would strongly expect it to agree. The primitive Anzblyopone species have workers agi-eeing with the archetype more or less closely in character Nos. 3, 7) 10) I I) 13 and 15. hlales of the larger and more primitive species of Amblyo- pone also agree in No, I.
The Nothomyrmecia macrops worker agrees with Nos. 2) 4 (more or less)) 5, 7) 10, 11) 12) 14 and 15.
The Mcthocha stygia female agrees well to fairly well with all character states except 10 and 12.
================================================================================
PREVIOUSLY HYPOTHESIZED ANCESTOR
3e
comp~ete~ separated patiob
I *
short bidentate
================================================================================
19671 Wilson, Carpenter, Brouln - A4esozoic Ants 17 Our analysis of Sphecomyrma, incomplete as it must be) neverthe- less suggests several promising lines of investigation in the future. First and foremost) of course, is the search for more Cretaceous ants 2nd allied aculeate groups. Perhaps the Magothy amber will ~ield more material of interest,
Second, we should pay closer attention in the future to comparisons in morphology, physiology) and behavior between the primitive myrmecioids and primitive poneroids. Dif- ferences should be related to the emerging new form of the formicid cladogram, while similarities should be examined with reference to the question of whether they are monophyletic or convergent. Finally, as a better idea is formed of the relationships of the ants to certain living wasp families) the biology of the latter needs to be examined more closely for clues concerning the origin of social life in ants. ACKNOWLEDGEMENTS
We gratefully acknowledge the splendid cooperation of Mr, and Mrs. Edmund Frey, as well as the intermediary aid of Dr. Donald Baird of Princeton University and kIr. David Stager of the Newark Museum. Our separate research programs, within which the analysis of Spheconzyrmz was undertaken cooperatively, have been supported by grants from the National Science Foundation: NSF GB-5574X ( Brown), NSF GB-2038 (Carpenter) ) and NSF GB-I 634 (Wl- son) .
SU~~~ARY
Two worker ants preserved in amber of Upper Cretaceous age (>lagothy Formation) have been found in New Jersey. ?-hey are the first undisputed social insect remains of ~lesozoic age) and extend the existence of social life in insects back to approximately 100 million years. They are also the earliest known, certainly assignable aculeate Hymenoptera. The species, Sphecomyrma freyi, is considered to EXPLANATION OF PLATE 4
A comparison of the archetypal ant as hypothesized by the authors before the discovery of Sphccomyrma (e.g., Brown, 1954; Brown and Wilson, 1959), with Sphecomyrma itself. The fine details of body shape are made the same in this drawing for convenience but do not enter into the main features to which phylogenetic speculation has been directed. This comparison is pre- sented to indicate the degree of precisian of earlier phylogenetic reasoning. Examination of the Sphecomyrmu specimens proved the hypothesis wrong in essentially only one major respect: we had guessed that an ant-like mandible developed before an ant-like petiole, but the reverse proved to be the case.
================================================================================
Psyche
[March
represent a new subfamily (S~heco~nyrminae) more primitive than any previously known ant group. It forms a near-perfect link be- tween certain non-social tiphiid wasps and the most primitive myrme- cioid ants.
REFERENCES
BEQUAERT, J. C. AND F. M. CARPENTER
1941. The antiquity of social insects. Psyche 47: 50-55. BERRY, E. \V.
1904. The Cretaceous exposure near Cliffwood, N. J. Amer. Geol. 34: 252-260.
1905. Additions to the fossil flora from Cliffwood, New Jersey. Torsey Bot. Club Bull. 32: 43-48.
1906. brief sketch of fossil plants. New Jersey Geol. Survey Ann, Report State Geol, for 1905: 97-133.
1906.
The flora of the Cliffwood clays. New Jersey Geol. Survey Ann. Report State Geol. for 1905 : 135-172.
1907.
New species of plants from the Magothy Formation. Johns Hop- kins Univ. Circ. n.s. 1907(7) : 82-89.
BROWN, W. L., JR,
1954. Remarks on the internal phylogeny and subfamily classification of the family Formicidae. Insectes Sociaux I: 21-31. 1960. Contributions toward a reclassification of the Formicidae. 111. Tribe Amblyoponini (Hymenoptera). Bull. Mus. Comp. 2001. Harv. 122: 143-230.
BROWN, W. L., JR. AND W. L. NUTTING
1950. Wing venation and the ~hylogen~ of the Formicidae (Hymenop- tera). Trans. Amer. Ent, SOC. 75: 113-132, pl. 8, 9. BROWN, W. L., JR, AND E. 0. WILSON
1959. The search for Nottiomyrmecia. W. Austral. Natur. 7: 25-30. CARPENTER, F. M.
1929. A fossil ant from the Lower Eocene (Wilcox) of Tennessee. J. Wash. Acad. Sci. 19: 300-301.
1930.
The fossil
ants of North America. Bull. Mus. Comp. 2001. Harv. 70: 1-66, PI. I-ll*
CARPENTER, F. M., J. W, FOLSOM, E. 0. ESSIG, A. C. KINSEY, C. T. BRUES, M. W. BOESEL, AND H. E. EWING
1934. Insects and arachnids from Canadian Amber. Univ, Toronto Stud., Geol. Ser. 40: 7-62.
CLAUSEN, C. P.
1941. Entomophagous insects. New York and London, ~cGraw-Hill. Cf. p. 298 ff.
EMERSON, A. E.
1965. A review of the Mastotermitidae (Isoptera), including a new fossil genus from Brazil. Amer. Mus. Novit. 2236: 1-46. EMERY, C.
1891. Le formiche delljambra siciliana nel muse0 minesalogico dell'uni- versiti di Bologna. Mem. R. Accad. Sci. 1st. Bologna (5) 1 : 141-165, pl. 1-3.
================================================================================
19671 Wilson, Carpenter, Broupn -Mesozoic Ants I9 GRowr, J. J., J. S. PENNY, and C, R. GROOT 1961. Plant microfossils and age of the Raritan, Tuscalosa, and Magothy formations of the Eastern United States, Palaeontographical (B) 108: 121-140.
HAGEN, H.
1874. On amber in North America.
Proc. Boston SOC. Nat, History 16:
1-7.
HOLLICK~ A.
1905. The occurrence and origin of amber in the Eastern United States. Amer. Nat. 39: 137-145.
KNOWLTON~ I?. H.
1896. American amber-producing tree. Science, NS 3 : 582-584. LANGENHEIM, R. L.! JR., C. J. SMILEY, AND JANE GRAY 1960. Cretaceous amber from the Arctic Coastal Plain of Alaska. Bull. Geol. Soc. Amer. 71: 1345-1356.
PAGDEN, H. T.
1949. Descriptions and records of Austro-Malaysian Methocidae and Mutillidae (Hymenoptera). Trans. R, Ent. SOC. Lond. 100 : 191-231.
PATE> V. S. L.
1947. A conspectus of the Tiphiidae, with particular reference to the Nearctic forms, (Hymenoptera! Aculeata.) J. N. Y. Ent. SOL 55: 115-145.
REID, J. A.
1941. The thorax of the wingless and short-winged Hymenoptera. Trans. R. Ent. Soc. Lond. 91: 367-446.
SHAROV, A, G.
1957. First discovery of a Cretaceous stinging hymenopteron (ACU- leata). (In Russian.) Dokl. Akad. Naulc. 112: 943-944. STOVER, L. E.
1964. Comparison of three Cretaceous spore-pollen assemblages from Maryland and England. Palynology in Oil Exploration, S.E.P.M. Spec. Pub]. 11: 131-142,
TROOST, G.
1821. Description of a variety of amber, and of a fossil substance supposed to be
the nest of
an insect discovered at Cape Sable,
Magothy River! Ann-Arundel County! Maryland. Amer. Jour. Sci, 3 : 5-8.
HEELER, %'. M.
1914. The ants of the Baltic amber. Schrift. Phys.-okon. Ges. Konigs- berg 55: 1-142.
WILSON, E. O., T. EISNER, G. C. WHEELER AND J, WHEELER 1956. ~neu?-rtu~ ~imoni Emery, a major link in ant evolution. Bul1. Mus, Comp. 2001. Harv. 115: 81-99, p1. 1-3.
================================================================================
Volume 74 table of contents