Howard E. Evans.
Studies on Neotropial Pompilidae (Hymenoptera) IV. Examples of Dual Sex-Limited Mimicry in Chirodamus.
Psyche 75:1-22, 1968.

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PSYCHE
Vol. 7 j March, 1968 No. I
STUDIES ON NEOTROPICAL
POMPILIDAE (HYMENOPTERA)
IV. EXAMPLES OF DUAL SEX-LIMITED
MIMICRY IN CHIRODAMUS1
Museum of Comparative Zoology
INTRODUCTION
Taxonomy is considered a branch of biology, but it might equally well be regarded as a special kind of detective work. One gathers evidence from diverse sources and tries to build a case for the natural classification of a group. On occasion the result is a "hung jury": the evidence does not fit together into a convincing picture. On oc- casion - but all too rarely - the evidence leads on into broader problems than originally supposed and provides new insights into bio- logical phenomena. I believe that the present investigation is such a case, and I shall present the evidence much as it came to me. Much of it is circumstantial or even suppositional, but not any more so than is often true in taxonomy. The conclusion - that certain South American spider wasps of the genus Chirodamus have males that are Batesian mimics of one complex of wasps and females that are Miil- lerian mimics of a very different complex-is so far as I know a novel facet of the mimicry problem.
The story begins in 1945, when Nathan Banks described a new genus of pompilid wasps from South America, calling it Amerocnemis. He based this on one female, described as A. bequaerti, and several males which he did not describe at that time. In his review of the South American Pepsinae in 1946, Banks described three species from ehe male sex: argentinica, brasiliensis, and longula. In 1957, Townes 'Acknowledgment is made to the William Morton Wheeler Fund of the Museum of Comparative Zoology for assuming the cost of the colored plate and of publication.
Manuscript received by the editor December 5, 1967. Psiffte 75:)-22 11968). http//psychr enlclub.mg!?S/75-001 him)



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recognized bequaerti as a species of Priocnessus and correctly placed Amerocnemis in the synonymy of that genus. The three "male" spe- cies, although relatively large and striking, have remained unassigned generically and unassociated with any female. Banks noted that these species all have what he called "markings suggestive of Batazonus", by which he meant that their color pattern suggested several species of Poecilopompilus (="Batazonus" of Banks, more properly Bato- zonus) in the subfamily Pompilinae. The Poecilopompilus in ques- tion (and the "male ^merocnemis7') all in fact belong to a very large mimetic complex of tropical America, centering around quite a number of social Vespidae sharing a more or less common yellow, ferruginous, and black pattern (Figs. I -9) . Although males of these species have been accumulating in the collections of the Museum of Comparative Zoology over the past few years, I found no females to match them. Then, in the summer of 1966, Charles C. Porter of Harvard University returned from Argentina with an excellent series of Banks' "Amerocnemis" argen- tinica, all taken January through April at Horco Molle, Tucumin (Fig. 9). The variation in this series was considerable, and led me to my initial conclusion, that Banks' brasiZicnsis was no more than a rather dark extreme of the same species (the Poecilopo7npilus of eastern Brazil also tend to be darker). Comparison of the genitalia of the types of Banks' two species has confirmed this conclusion. At the same locality, Porter collected an undescribed female Chirodamus having a rather narrow front and reduced body pubes- cence but otherwise typical of this genus. Like many Chirodamus, this was a black wasp with bright orange wings, a member of a large complex of aposematically colored "Pepsis-mimics" which ranges all the way from the western United States to Patagonia (Fig. 10). This complex includes Pompilidae of several different genera (Figs. EXPLANATION OF PLATE 1
Fig. 1. Cerceris sp., Q (Sphecidae) . Fig. 2. Mischocyttarus alfkenii zikanii Richards, Q (Vespidae) . Fig. 3. Poecilopompilus polistoides Smith, Q (Pompilidae). Fig. 4. Colpotrochia sp. 1, 8 (Ichneumonidae). Fig. 5. Dolichomitus zonatus Cresson (subsp.) , ? (Ichneumonidae). Fig. 6. Colpo- trochia sp. 2, 8 (Ichneumonidae). Fig. 7. Cubus sp., 8 (Ichneumonidae). Fig. 8. Ephialtes bazani Blanchard, Q (Ichneumonidae). Fig. 9. Chiro- damus argentinicus Banks, 8 (Pompilidae), Fig. 10. C. argentinicus Banks, Q (Pompilidae). Fig. 11. Priocnemella omissa Banks, Q (Pornpilidae). Fig. 12. Chirodamus longulus Banks, Q (Pompilidae). Fig. 13. Priocne- mioides unifasciatus luteicornis Lepeletier, Q (Pompilidae). Fig. 14. Chiro- damus longulus Banks, (Pompilidae). Fig. 15. Apoica thoracica Buysson, Q (Vespidae).




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4 Psyche [March
I I, 13) as well as Ichneumonidae, Diptera of at least two families, several aegeriid moths, and at least one staphylinid beetle and one grasshopper. Members of this complex vary from quite small to some of the largest Hymenoptera known: apparently the black and orange coloration is effective at several size levels. The females of Pepsis and other Pornpilidae form the Mullel-ian center around which the many non-stinging members are arrayed as presumably Batesian mim- ics (including, of course, the males of these same Pompilidae). This complex includes no social wasps that I am aware of. r 7
I he resemblance of arptinica males to those of the unknown Chirodamus (on structural features, certainly not on color), led me to look into the third "male Amerocneinis", longula Banks. This larger species was described from the Rio Purus, in western Brazil, and we have an excellent series collected at Quincemil, Peru, by Luis Pefia (Fig. 14). To my satisfaction, I found several specimens of an orange-winged Chirodamus taken by Pefia at the same time and place and showing many structural resemblances to the male languid (Fig. 12). In this case the female belonged to the same mimetic complex as the presumed female of argentinica, but the male was too large and too brown to be a possible mimic of the same complex as the male argentimca. However, a scanning of the social wasps of this area, including those taken by Pefia at the same locality, reveals that there are several possible models (Fig. I 5).
A more detailed study of the structure of the pompilid wasps in question has convinced me that these sex associations are correct and that these species properly belong in the widely distributed, protean genus Chiroda71ms (in the sense of Townes, 1957). Having reached this decision, it was natural for me to look for other species which might also be "dual mimics". I immediately considered the possibility that pentodon Arli, from eastern Brazil, might represent another example. This species was actually described in the genus Batozonus, but Ah% excellent figures make it clear that it is a close relative of argcntinii-us. In l\Iai-ch, 1966, Henry and Marjorie Townes collected a fine series of this species along with tawny-winged females belonging to a species which has been called vitreus Fox, and I am convinced that this is a third example of dual mimicry, although in this case the wing color of the female is less intensely orange than in most Pepsis and other apo~ematically colored spider wasps. I have
also discovered two additional species, each represented by a single male, which belong to this complex. These are described below.



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19681 Evans - Neotropical Pompilidae 5
A search for possible examples in other genera has also been pro- ductive. Fo1- example, the male of Austrochares mexicanus Dreisbach is colored strikingly like Poecilopompilus flavopictus and several social wasps; the female, however, is black with an orange abdomen, a com- mon pattern among wasps and probably aposematic (Evans, 1966). The South American Austrochares autrani (Holmberg) is similarly colored. In both cases the sexes have only recently been associated. It should be added that there are many cases in which the females are aposematically co~lored or colored so as to resemble Mutillidae 01- other powerful stingers, but in most such cases the males are simply black and non-mimetic (e.g., Psorthaspis formosa, Aporus idris; Evans, 1966). Also, in nearly all other cases of Pepsis mimicry, both sexes share the bright orange wings and dark bodies (in Pepsis, 1Yem.i- pepsis, Priocnemioides, many Chirodamus, Cryptocheilus, etc.) . In a number of cases certain species are Pepsis-mimics within the range of orange-winged Pepsis, but non-mimetic, black wasps outside of the range of the model (e.g., Cryptocheilus idoneum; Townes, 1957). Dual mimicry appears to be a relatively uncommon phenomenon in ?he Pompilidae, though doubtless more cases will be discovered. Henry Townes has pointed out to me that a generally similar sexual dimorphism in color occurs in many ichneumon wasps, particularly in the subfamily Ichneu~noninae, and in certain Scoliidae in which there are large patches of orange in the females while the males lack the orange and are black with yellow banding. Such instances also
suggest that each sex has evolved to copy a different aposematic or mimetic pattern, although the resemblance is of a more generalized type than that described here. The possible origin of such color dimorphism is discussd following a more detailed description of dual mimicry in Chirodmzus.
DESCRIPTION OF DUAL MIMICRY IN CHIRODAMUS It should first of all be pointed out that many species of Chirodamus have black or blue-black bodies and bright orange wings in both sexes, for example, the western North American pyrrhomelas Walker and the South American fidanzae Holmberg. Other species, in many cases those occurring in areas where orange-winged Pepsis are rare or absent, are black with black or hyaline wings (e.g., C. fortis Cres- son, in eastern United States, and C. kingii Haliday, the type species, in Patagonia). Members of the argentizicz/s group range from northern Argentina to Brazil and Ecuador, an area in which both orange-winged Pepsis and conspicuously banded social Vespidae and their various mimics are very common.




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6 Psyche [March
Since the case of C. argentinicus is best documented, I will discuss it first and at greatest length.
Charles C. Porter collected the first
known female of this species at Horco Molle, Argentina, and the Townes took a second female at this same locality. This is a locality in which a very similarly colored Priocnemioides, P. unifasciatus luteicornis (Lepeletiei-) is common and in which other orange-winged species of Chiroda/nus, Prioc-n~~///ioides, and other genera occur. As mentioned earlier, this is a very common Miillerian mimetic pattern, with members occurring all the way from the western half of the United States to central Argentina and Chile. It includes pompilids of other tribes and subfamilies (e.g. Notocyphus, Abernessia) as well as an assortment of Diptei-a, Lepidoptera, Coleoptera, and Orthoptera. In this instance, the resemblance of the female C. argentinicus to that of P. unifasciatus luteicornis is especially close; they are similar in size and in all details of coloration of the body, wings and an- tennae (Figs. 10, 13). It seems probable that luteicornis is the major model in this area.
Charles Porter collected males flying in the vegetation along with several species of Ichneumonidae which resemble it closely. Certain of these are species which produce an odor unpleasant to humans and presumably serving in defense against avian predators (e.g., Ephialtes bazani, Fig. 8). In other localities this same color pattern was re- peated but included other Hymenoptera. For example, at Alto la Vina, in Jujuy, it was found to include the pompilid Poecilopompilus polistoides (Fig. 3), a species of the sphecid genus Cerceris (Fig. I ) , and the social wasp Mischocyttarus alfkenii zikanii Richards (Fig. 2). Certain species of social wasps of the genera Polybia and Stelo- polybia also share essentially this same color pattern, as do certain Diptera, day-flying moths, and even leafhoppers. It is impossible
to define this mimetic complex fully at this time or to list with cer- tainty i'ts components in any given area. The following list includes species taken by Porter in localities in northwestern Argentina in fundamentally similar habitats and sufficiently alike to deceive a hu- man collector.
VESPIDAE
Mischocyttarus alfkenii zikanii Richards (Fig. 2) POM PILIDAE
Poeciloponzpilus polistoides Smith ( Fig. 3 ) Chirodamus argentinicus Banks (males only) (Fig. 9) SPHECIDAE
Cerceris sp. (Fig. I )




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19681 Evans - Neotropical Pompilidae
ICHNEUMONIDAE
Carin odes sp.
Colpotrochia sp. I (Fig. 4)
Colpotrochia sp. 2 (Fig. 6)
Cubus sp. (Fig. 7)
Dolichomitus zonatus Cresson (subsp.) (Fig. 5) Ephialtes bazani Blanchard (Fig. 8 )
Ichneumoninae (Genus and Species?)
Metopius sp.
Theronia lineata Fabricius
Porter has supplied me with notes on the behavior and occurrence of some of these wasps. The male Chirodamus were taken along trails in wet forest, usually flying in undergrowth about 1-4 feet off the ground. He notes that of all members of this complex they have the fastest flight, "usually appearing only as a furtive c ell ow streak against a dark background of foliage". Theronia, Carinodes, and an unidentified member of the Ichneumoninae also flew here, although somewhat more slowly, while Ephialtes bazani, a species with a disagreeable odor, occurred here but was quite sluggish in its flight. The species of Colpotrochia tended to occur in more open situations, and one of them was one of the most abundant insects at Horco Molle, sometimes swarming in high grass in sunshine but being scarcer in the forest. Since workers of the various social wasps tend to forage in a variety of situations, they may of course provide a unifying factor for wasps of somewhat diverse modes of life. All of these wasps are essentially inhabitants of vegetation somewhat above the ground, in contrast to the majority of "Pepsis-mimics", which spend much time walking over the ground in the search for terrestrial spiders.
In this instance we know that the male Chirodamus fly in the same situations as other, similarly colored wasps, but in the other cases of supposed dual mimicry the evidence is more indirect. The female C. longulus (Fig. 12) is very similar in appearance to that of C. argentinicus (Fig. 10) and to Priocnemioides unifasciatus lutei- cornis (Fig. 13). Luis Pefia also took Priocnemella omissa Banks (Fig. I I ) at the same locality as a series of longulus, and there are of course species of Pepsis of basically this same coloration in this same area. Tlhere seems no question that the female longulus belongs to this same complex of "Pepsis mimics".
The male of longulus is patterned with brownish-ferruginous and fuscous, with dull yellowish markings on the head and thorax; the abdomen is weakly banded with fuscous but lacks yellow markings



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(Fig. 14). Its larger size and quite different coloration indicate that it belongs to a different mimetic complex than the male argen- tinicus. Luis Pefia collected, at the same time and place as a series of Zongulus, a long series of Apoica thoracica Buysson, a social vespid known to be an aggressive stinger (Fig. 15). The specks of Apoica have enlarged ocelli and are nocturnal or crepuscular. It should be noted that the ocelli of Chirodamus longulus are also unusually large for a pornpilid, suggesting that this species, so similar to Apoica thoracica in size and coloration, may also be crepuscular. Other social Vespidae of similar size and coloration occurring within the range of longulus (but presumably diurnal) include Polistes occi- pitalis Ducke and Mischocyttarus tomentosus Zikin. These species
lack the infuscation along the anterior border of the fore wing oc- curring in Apoica, and in this respect are more like Chirodamus ZonguZus.
In the case of Chirodamus vitreus, from eastern Brazil, the females appear to be imperfect "Pepsis mimics" since the wings are only faintly tinged with orange. It is worth noting that some of the species of Priocnemioides occurring here also have the wings either weakly suffused with orange or only partially of this color (brasilien- sis, coeruleus): indeed the wings of P. unifasciatus luteicornis are notably darker in eastern Brazil than in Argentina. Perhaps these
species represent a subcomplex of Mullerian mimics characteristic of this area. The male vitreus is basically similar in color to that of argentinicus and is doubtless a member of much the same complex, centering around certain social wasps. It is of generally darker color than arpentinicus, some individuals being mostly black, but it should be noted that many groups of wasps have species of generally darker coloration in this region, e.g., Poecilopompilus costatus (Pompilidae) and Polybia sericea (a social vespid). We have a great deal to learn about the composition of various mimetic complexes in the neotropics, and it seems certain that final clarification will involve across-the- board studies of several different families of wasps and, in fact, sev- eral orders of insects.
The two new species described below from males only, imitator (from Ecuador) and impensus (from Paraguay) are both large, i ale wasps, and although the two are not closely related I suggest that the model for both may be the large, aggressive social wasp Apoica pallida, the range of which includes both countries. The male of
imitator has enlarged ocelli, like that of longulus and like the species of Apoica, so it may well be crepuscular. I predict that the females



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19681 Evans - 'Neotropical Pompilidae 9
of these two species will be found to have black bodies, partially orange antennae, and largely orange wings: that is, that they will be ('Pepsis mimics" like those of other members of this species group. One is, of course, curious to know what selection pressures pro- duced males that are Batesian mimics of social wasps and females that are Alullerian "Pepsis-mimics". As pointed out earlier, the males, in their irregular searching flights, remain mostly well above the gi-ound, chiefly in herbs and bushes that may contain workers of social wasps. At the same time the females spend the greater part of their time on the ground searching for spiders, in the same habitat as the various orange-winged species of Pepsis, Priocmioides, and other genera. It is true that orange wings like those of the females seem to serve the males of most related wasps perfectly well: pre- sumably birds and lizards learn to avoid this color and do not dis- criminate between the sexes. Evidently the males of these species of Chirodamus have achieved a still more effective level of protection by resembling certain common social wasps. It is probable that other cases of marked color dimorphism, such as in the genus Austrocfzares and in certain Scoliidae and Ichneumonidae, as mentioned earlier, reflect the fact that males and females spend the greater part of their time in slightly different situations, such that selection has favored a different mimetic pattern.
In con~plexes such as these the distinctions between Batesian and Mullerian mimicry and between the latter and generalized aposematic patterns are obviously unclear. I have spoken of male Pepsis as Batesian elements in their complex, but the fact is that both sexes of at least some species of Pepsis have a characteristic odor, and this odor may well be repellant to predators. Similarly, the odor of the slow-flying ichneumon Ephialtes may serve to reinforce its mimicry of social wasps - a bird that "forgets" the mimetic pattern is re- minded, not by a sting, but by a chemical stimulus. It is probable that many male and non-stinging female Hymenoptera are not fully palatable. Furthermore, many males, when seized, undergo move- ments of the abdomen suggestive of stinging, and in several groups the genitalia or apical stei-nite have evolved into a pointed "pseudo- sting", often capable of pricking but never supplied with poison glands. That "palatability" is no simple phenomenon has been further shown by Brower et a1 (1967)) who found that some races of the monarch butterfly are actually palatable "automimics" of distasteful members of the same species that have fed as larvae on poisonous species of milkweeds.




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In the case of Chirodamus argentinicus and its allies, and the mimetic complexes involved, it is obvious enough that we know little of such matters. Indeed, the fact that to our eyes these wasps re- semble one another in color and form does not necessarily mean that they look alike to predators and thereby gain protection. However, no one who has spent much time in the neotropics is likely to question the existence' of large complexes of wasps and wasp-like insects that share common color patterns and flight behavior. Experimental work such as that of Brower and Brower ( 1965) on drone flies as mimics of honeybees lends support to the belief that such mimicry is effective against vertebrate predators. Nevertheless, each case is different and must be weighed on its own merits. The amount of work waiting to be done in this field is frightening. For the moment, the concept of dual mimicry may at least serve a useful purpose in helping to as- sociate the sexes in certain refractory sections of the Pompilidae and other groups.
TAXONOMIC TREATMENT
A brief description of Chirodamus was provided by Townes ( 1957, p. I I), who also figured the wings of a North American species (his Fig. I ). As Townes pointed out, some of the diversity in this genus involves characters elsewhere given generic value. For the present, however, it seems best to use the generic name in a broad sense, using the category of species-group for the more distinctive complexes of species, thus avoiding nomenclatorial changes that can be no more than tentative until the group has been studied from a world point-of-view. The species treated here are considered to con- stitute the argentinicus species-group. Members of this group have departed considerably from the usual robust, hairy form of the genus, but in my opinion there is no structural discontinuity sufficient to justify generic or even subgeneric status for this group. For the record, I have included a drawing of the male genitalia of C. fidanzae (Holmberg) (Fig. 21), an Argentinian species of robust body form, densely hairy and otherwise similar to more "typical" Chirodanzus* Although the claws of the male are bifid, it is otherwise very unlike argentinicus and its allies and most certainly not a member of this group. The drawings demonstrate the basic similarity of the genitalia, however: the basal hookets are double, there are large, hairy lobes at the base of the digitus, the digitus itself is bilobed, and the para- meres bear a series of stout pegs.
This supports the belief that the
argentinicus group should be included in Chirodamus despite super- ficial differences.




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Fig. 16-21.
Male genitalia of Chirodamus spp., ventral aspect. Fig. 16. C. imitator n. sp,, holotype. Fig. 17. C. longulus Banks. Fig. 18. C. impensus n. sp., holotype. Fig. 19. C. argentinicu~ Banks. Fig. 20. C. witreus Fox. Fig. 21. C. fidanzae Holmberg.




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Characters of the argentinicus species-group.- Antennae, legs, and body relatively slender for the genus, the abdomen of the male especially slender toward the base; body with a very limited amount of erect hair) the propodeum at most weakly hairy on the sides; pos- terior tibiae of female with a double row of strong serrations. JVings without a well-defined irregularity at the base of the first discoidal cell. Front and vertex unusually narrow for the genus; posterior margin of pronotum angulate ; psopodeum sloping smootl~ly, with or without rugae; apical tarsal segments of female bearing lateral spines; claws of female strongly dentate, the outer ray curved so as to be nearly parallel to the inner ray; claws of male slender, curved, deeply bifid. Females black, the antennae orange apically, the wings varying from yellowish brown to bright orange; males with a com- plex pattern of yellow, ferruginous, and fuscous, the wings hyaline, tinged with yellowish brown.
ICey to species of argentinicus group
Females
I. Front and vertex relatively broad, upper interocular distance sub- equal to or slightly exceedilng length of third antennal segment; ocello-ocular line slightly exceeding postocellar line ................ .................................................................. argentinicus (Banks) Front and vertex unusually narrow, upper interocular distance much shorter than third antennal segment; ocelli rather hrge, postocellar line exceeding ocello-ocular line ............................ 2 2. Wings orange, ,with a very narrow fuscous outer margin; at ....................
least the outer 7 antennal segments orange above ...................................................................... Zongulus (Banks) IVings translucent, lightly tinged with yellowish and with fus- cous, ; outer five antenna1 segments orange above .................... ............................................................................ vitreus (Fox)
A fules
I. Ocelli unusually large, in a compact, elevated triangle, the lateral ocelli removed from the eye margins by at most about half