Comprehensive Description

provided by Smithsonian Contributions to Zoology
Anthrax cephus Fabricius

Anthrax cephus Fabricius, 1805, p. 124.—Wiedemann, 1828, p. 297.—Macquart, 1840, p. 59.—Walker 1849, p. 266.

Argyramoeba cephus.—Kertesz, 1909, p. 62.

MALE.—Integument generally black; legs, pleura, and genitalia reddish brown; integument mostly grayish or brownish pruinose, margins of eyes and lower part of occiput silvery pruinose. Front with black setae and a few black scales below; face with black setae extending upward to antennae, a few white hairs and scales below. Scales and setae on occiput black; fringe of pile on posterior margin black above, white or mixed brown and white below. First antennal segment about as long as apical width; second segment globular; base of third segment flattened mesolaterally, tapering gradually to styliform part which is about equal to base; style one-half to three-fourths as long as styliform part.

Mesonotum and scutellum with fine black setae and linear black scales, sometimes brown or white scales in front of base of wings and white scales rarely present at apex of scutellum. Sternopleuron, mesopleuron, and anterior part of pteropleuron with fine black setae and black and/or white, threadlike scales; upper half of mesopleuron and pteropleuron with some coarse black setae and black and/or white pile. Pile on prosternum, propleuron, and anterior margin of mesonotum black, white, or mixed; postalar tuft of pile black. A few black or white hairs behind spiracle; anteroventral corner of hypopleuron with a few black or white hairs or threadlike scales. Fore coxa with black setae and black and/or white pile and scales; middle and hind coxae with black setae and black or mixed black and white scales.

Wing (Plate 4c) entirely black pigmented or subhyaline apically. Stigmatic area lightly pigmented; calypter pigmented, fringe of hairs brown. R–m crossvein located one-third or two-fifths of way from origin to bifurcation of vein M1+2; contact of cells 1M2 and Cu1 one to two times as long as base of cell Cu1. Vein R4 with long spur at base. Cell 2A as wide as cell 1A.

Scales on legs black. Middle femur with one to four macrochaetae anteroventrally and one to several macrochaetae postmedially on anterior side; hind femur with four to seven macrochaetae anteroventrally. Hind tibia with double row of macrochaetae anterodorsally; scales mostly recumbent.

Pile on lateral margins of first abdominal tergum white, sometimes a few black hairs posteriorly; lateral margins of terga two through four, and sometimes five and six with dense black pile. Posterior margins of first tergum, discs of terga two through four and sometimes five and six with sparse black setae and linear black scales. Seventh tergum and sometimes all or lateral parts of terga five and six with dense, overlapping, posteriorly-produced, silver-white scales. Setae and scales on sterna entirely black, or white (or yellow) anteriorly and black posteriorly.

MALE GENITALIA (Figure 59).—Gonocoxites long and narrow, narrowing abruptly before very narrow tips in lateral view, apices infolded mesally, forming narrow, acuminate, incurved lobes in ventral view, setae evenly distributed basally beyond medial fold, extreme apices bare. Basal segment of gonostylus oblong, with a few setae apically; distal segment bulbous in ventral view, with a diagonally truncate tip, dorsal margin tapering to ventral margin in lateral view; fine setae present on basal part. Apex of epiphallus flattened dorsoventrally, apex rounded, sharp, recurved lateral lobes present preapically. Dorsal bands narrow, proximate medially, with a few setae before junction. Base of aedeagus narrow, but bulbous, tapering to junction with ventral bands after junction of dorsal bands, with enlarged area before junction of dorsal bands.

FEMALE.—Similar to male. White pile and scales sometimes more extensive on pleura. Fore and middle femora and tibiae sometimes with white scales posteriorly. Hind femur sometimes with complete row of macrochaetae anteroventrally. Apex of wing sometimes hyaline as far back as a line running from tip of subcosta to tip of M2 in specimens from Central America. Silver scales on apex of abdomen restricted to lateral parts of fifth tergum and sometimes to the sixth and seventh.

FEMALE GENITALIA (Figure 77).—Tenth tergum with about 21 spines on each side. Ventral arm of ninth tergum undulate, not expanded apically. Dorsomedial angle of sclerite on each side of gonopore produced dorsally as a short, rounded lobe about as long as broad; lateral arm short, broad, parallel sided and truncate apically; ventral arm broadened medially parallel to meson, narrowing below and slightly curved toward meson. Spermathecal ducts about as long as bulbs; first section very short; second section slightly shorter than third which is slightly expanded and bent at a right angle apically; bulb elongate elliptical, broadest submedially, slightly constricted postmedially, without differentiated distal section.

DISTRIBUTION.—Anthrax cephus occurs in tropical forests from southeastern Brazil through the Amazon Basin (Map 17).

TYPE.—According to notes supplied by R. H. and E. M. Painter, the type male of Anthrax cephus is in the Copenhagen Museum. Tips of the wings are broken off, the antennae are missing, and the body is greasy. It carries the label “A. cephus ex Am. Mer. Schmidt.” The description of the type agrees with typical specimens of A. cephus. Fabricius gave “America Meridionali” as the type-locality.
bibliographic citation
Marston, Norman L. 1970. "Revision of New World species of Anthrax (Diptera: Bombyliidae), other than the Anthrax albofasciatus group." Smithsonian Contributions to Zoology. 1-148. https://doi.org/10.5479/si.00810282.43

Comprehensive Description

provided by Smithsonian Contributions to Zoology
Anthrax cephus Group

The cephus group is the largest and most diverse group in the genus Anthrax in the New World. Thirty names have been proposed to date in the group. Of these, thirteen are synonyms, one is a homonym, and one is relegated to subspecific rank. In addition, twelve new species and one new subspecies are described here, making a total of 29 taxa known from North and South America.

Specimens of the cephus group may be separated from species of other groups most readily by the setae on the face, which extend almost to the level of the antennae rather than restricted to the lower and lateral margins. Anthrax plurinotus of the trimaculatus group has the setae distributed in this way, but it has distinct, isolated spots at the bases of the apical cells.

MAP 10.—Distribution of Anthrax melanopogon and A. cybele.

Approximately 1400 specimens in this group have been studied. These represent the majority of specimens in North and South American museums. All except about 20 have been assigned with relative certainty to the various taxa recognized. The few unassigned specimens may represent individual variants, intermediates between species or subspecies, or possibly distinct taxa too poorly represented to be recognized. These specimens are discussed under the species to which they seem most closely related.

Group Description

Body generally black; tibiae and male genitalia usually red or yellow, femora and parts of thoracic pleura, basal antennal segment, and parts of abdominal sterna sometimes red or yellow. Pruinosity generally gray and brown, silver along margins of eyes, sometimes velvet black above on thorax and abdomen. Head globoid, eyes separated at vertex by 1.0 to 1.5 times width of ocellar tubercle in male, 2.0 to 2.5 times its width in female. Antennal sockets separated by 0.25 to 1.0 of their diameters, separated from eye margins by 0.5 to 0.75 of their diameters. Face projecting slightly above level of eyes, oral margin evenly rounded or obtusely angular. Front covered with light or dark setae and sparse lanceolate scales of variable color. Face with dense setae extending from oral cavity almost to antennal sockets; sparse scales along eye margins and sometimes over entire face. Setae and scales on occiput and fringe of pile on posterior margin unicolorous or light below and dark above. First antennal segment narrow basally, more or less enlarged mesad apically, 0.75 to 2.0 as long as apical width and entirely covered with setae. Second segment lenticular or globoid, somewhat narrower than apex of first segment and with setae dorsally and laterally. Third segment bulbous or hemispherical basally, tapering abruptly or gradually to a styliform apex; base sometimes flattened mesolaterally, usually as wide as second segment in mesal view and slightly narrower in dorsal view; styliform part 0.5 to 1.5 times as long as base, 1.0 to 2.5 times as long as style; style 1.0 to 4.0 times as long as wide, with a distinct apical tuft of setae.

Mesonotum with fine setae scattered over disc and with bristles and coarse setae along lateral margins; recumbent linear scales present on disc, becoming curly and semierect along lateral margins; anterior margin with long hairs and setae. Scutellum with fine setae and linear scales on disc, and long setae and broader scales posteriorly and laterally. Mesopleuron with coarse setae and pile above, with fine setae, pile and erect scales below. Pteropleuron with coarse setae and fine pile and scales on anterior half, posterior part usually bare, rarely with long linear, curly scales. Sternopleuron with fine setae and linear or lanceolate, recumbent scales. Hypopleuron bare or with a patch of short setae or scales at anterior corner. Metapleuron sometimes with a patch of linear or lanceolate scales behind or below spiracle. Propleuron and presternum with long, erect pile. Postalar tuft of pile often with a few linear scales at base. Coxae with bristles and lanceolate semierect scales.

Wing pigmented anteriorly and basally, hyaline apicoposteriorly, or entirely pigmented, rarely nearly hyaline; no isolated spots present in apical part of wing. Posterobasal part of wing often greatly narrowed with posterior margin of cell 2A concave, or broadened with cell 2A twice as wide as cell 1A; alula well developed with posterior margin rounded, or reduced with posterior margin straight or concave. Base of cell R4 rounded, angled with a spur, or connected to vein R2+3 forming a sectoral crossvein; vein R4 without a medial spur. Base of cell R2+3 rounded or with a short or long spur. R–m crossvein located at basal fifth or two-fifths of cell 1M2. M crossvein sometimes supporting a spurious vein extending from near its apex to posterior margin near apex of vein Cu1. Contact of cells 1M2 and Cu1 0.5 to 3 times as long as base of cell Cu1. Calypteres lightly pigmented; knob of halteres more or less pigmented basally, usually yellowish apically.

Fore and middle femora with or without a more or less extensive anteroventral row of macrochaetae; middle femur sometimes with one or more bristles postmedially on the anterior side; hind femur with a more or less extensive row of bristles anteroventrally and sometimes with a few bristles apically on the posterodorsal and posteroventral sides. Fore tibia with rows of macrochaetae posteroventrally, posterodorsally and sometimes anterodorsally; middle and hind tibiae with rows of macrochaetae at all four angles; anterodorsal row on latter sometimes double. Scales on femora and tibiae entirely dark or sometimes light posteriorly; scales on hind tibiae semierect when a double row of macrochaetae is present anterodorsally.

Sides of first abdominal tergum with dense pile; sides of posterior terga with fine setae and semirecumbent or semierect linear or lanceolate scales, some pile often present laterally on terga two and three. Posterior margin of first tergum and surfaces of following terga with sparse, fine black setae and linear or lanceolate, dense, dark scales; broader, light scales often present along posterolateral margins of terga one through four. Lateral portions of fifth tergum and much or all of terga six and seven of male often with dense, overlapping, posteriorly or posterolaterally directed silver scales. Females often with patches of silver scales laterally on terga four, five, and six. Venter with fine long setae, and scattered lanceolate or linear scales of variable color.

Apices of gonocoxites of male genitalia rounded or acuminate, often with medial carinae defining a medial sulcus, rarely with lateral carinae; setae on gonocoxites sparse and coarse, sometimes more dense medially toward apex. Basal segment of gonostylus usually inconspicuous, rarely produced as an acuminate lobe or a broad, flat plate apically. Distal segment of gonostylus variable in form, usually extending apicolaterally, but rarely dorsolaterally. Apex of epiphallus with a dorsal spine, transverse shield, or raised plate, sometimes flattened with recurved lateral lobes. Basal part of aedeagus bulbous or tubular. Dorsal bands of epiphallus bare or with fine setae.

Eighth tergum of female with dense, fine hairs extending apically, basal medial process long, narrow and laterally flattened, or vestigial. Tenth tergum with one to thirty stiff spines on each side surrounding the cerci. Sclerites on ninth sternum usually hatched shaped, quite variable in form. Ventral arms of ninth tergum simple and acuminate or broadened apically. Spermathecal tubes of variable length, plastic or stiff, rarely contorted before bulbs; bulbs tubular to spherical or awl shaped, usually symmetrical, but sometimes with apex produced slightly laterad.

Taxonomic Characters

The extent of the wing pigmentation is the most valuable taxonomic character for separating species of the cephus group. The intensity of pigment is less useful, however, since it is difficult to define and varies considerably in certain species. A sectoral crossvein between vein R2+3 and the basal angle of vein R4 is present in the males of delicatulus and innubilipennis. The species related to pluricellus have an additional vein extending from the m crossvein to the wing margin just above the apex of vein Cu1. Thus, these species may key to the family Therevidae in some texts. This particular vein has both origin and insertion different from that extending from the m crossvein to vein Cu1 in species of the tigrinus group.

The form of the wing is a good taxonomic character. The species luctuosus and cathetodaithmos have the wing broader than is usual in species of Anthrax. In this case the cells are somewhat shorter and broader, particularly those of the anal area. Cell 2A is more than 1.5 times broader than cell 1A which is itself broadened. At the other extreme, the species of the argyropygus complex have the wings elongate and usually narrowed. The anal margin of the wing is greatly reduced with cell 2A narrower than cell 1A and with the posterior margin concave. The majority of the species are intermediate between these two conditions, but there is little intraspecific variation. The shape of the alula may be an excellent diagnostic character in that its margin may be straight or rounded, or it may even be vestigial as in argyropygus. The alula is defined as the membranous lobe at the base of the wing before the bases of cells 1A and 2A. It is clearly shown in Plate 3f.

Under the species analis and gideon several forms have been discriminated which have wing patterns grossly different from those of typical specimens. These forms probably were derived from isolated populations that were reunited subsequently and interbred freely with the parent population. Their origins are discussed under the section on evolution. As interpreted here, the forms have no taxonomic status but are briefly described lest ignoring them might lead to confusion.

The chaetotaxy of the legs is quite variable in the cephus group in contrast to the albofasciatus and oedipus groups. In the primitive condition there are four to six strong anteroventral bristles on the middle and hind femora. These are progressively reduced in the species of the analis complex, with analis and repertus having only one or two weak bristles apically. In the species of the cephus complex the number of femoral bristles may be increased. In addition, the species of the cephus complex, and delicatulus and innubilipennis, have one or more postmedial bristles on the anterior side of the middle femur. These are in the same position as those found on oedipus in the oedipus group. The species of the cephus complex also have the anteroventral row of bristles on the hind tibia doubled with the intermixed scales semierect.

The form of the antennae is quite variable among the different species. Since the form is very difficult to describe and varies somewhat due to unequal shrinkage during drying, it is not used extensively in classification. The drawings (Figures 95–120), however, may be helpful in verifying the identity of species.

The male and female genitalia are distinctive in almost all of the species. Those of the male are especially complex and have been most useful in segregating the species of the group. Since the best characters are internal, however, they are not emphasized in the key and diagnoses. The terms employed are illustrated in Figures 50 and 75.


Since the cephus group is restricted to North and South America, it is possible to consider more easily the origins and relationships of the species. Similar patterns of distribution have been observed in other bombyliid genera, and it is hoped that this discussion will provide an impetus for the future consideration of distributional patterns and species relationships in an evolutionary context. It should be emphasized that the patterns expressed here are strictly hypothetical. Alternative hypotheses may explain the distribution of the species, but the patterns described seem to fit best the available evidence.

The patterns have been determined by considering the distributions and phenetic relationships of the species along with their ecological preferences, where these are known, and, working backward through the Pleistocene, postulating the effects of climatic and geographical changes on the changing populations. Since the relationships of populations become less certain as one goes back through time, the origins of populations necessarily become more vague.

The evolution and dispersal of the species complexes of the group are illustrated in Figures 1–6. A hypothetical center of dispersal is indicated by a black circle and the main lines of dispersal radiate from it. Barriers which have resulted in speciation (or subspeciation) are indicated by broken lines. The hypothetical lines of dispersal leading to the present distributions of the taxa are indicated by narrow lines branching from the main trunks.

Several modes of speciation seem to have been involved in the evolution of the cephus group. The first is the classical case of separation by water as by the inundation of portions of the Isthmus of Panama during the interglacial periods of the Pleistocene, or by the separation of island faunas. According to Dunbar (1949), if the modern ice sheets of Greenland and Antarctica melted, as they apparently did during the interglacial periods, sea level would rise by as much as 100 feet, inundating low-lying areas in the Isthmus of Panama. Conversely, if the great continental ice sheets were restored, sea level would fall by as much as 300 feet, shifting the shore line seaward to the present 50-fathom line. The separation of populations in northwestern South America and southern Mexico has occurred repeatedly and apparently has been one of the primary factors effecting the evolution of the cephus group. Because only portions of the Isthmus were inundated, even during the period of highest sea level, islands would have been formed on which small populations could have been isolated. This may have been the origin of the species costaricensis.

Isolation of populations due to climatic change also has been an important factor in the evolution of the cephus group. The cool, wet climate during the glacial periods would have resulted in the shifting toward the equator of biotic zones and the increase in extent of forests, whereas during the interglacial periods biotic zones would have expanded toward the poles and areas of desert and grassland increased in extent (Martin, 1958). Because most of the species of the cephus group are forest inhabitants, the interruption of contiguous forest belts during dry periods has resulted in differentiation of populations. This apparently has occurred at intervals in south-central Brazil, northeastern Mexico, and south-central United States. Here again, small populations may be isolated on ecological islands surrounded by an inhospitable area, although no examples have been noted in the cephus group.

If such ecological islands were to change gradually to a new type of habitat (e.g., from forest to grassland) the isolates would be under strong selective pressure to adapt to the new conditions. The result of such a change, after dispersal in the new habitat, would be allopatric species or subspecies occupying adjacent habitats. This type of relationship has been observed commonly in the Bombyliidae and probably is the way analis and repertus became adapted to dry habitats. It would also explain the separation of argentatus and nitidus.

The species that retains the most generalized characters in the group is argentatus, which is endemic to the coniferous forests of northwestern United States and southwestern Canada. Since it has characters in common with several Palaearctic species of Anthrax, it seems probable that it was derived from a Eurasian ancestral population by way of the Bering Strait, and that it retains some primitive characters because of the lack of selective pressure in its relatively stable environment

The migration of the ancestral population into North America probably took place during the Pliocene, or perhaps slightly earlier, when floras similar to those in northwest United States existed in Alaska (Chaney, 1940). Although the continents of North America and Asia were connected several times during the glacial periods of the Pleistocene, the climate was probably too rigorous to allow the survival of Bombyliidae at that time (Hopkins, 1959).

Cockerell (1914) indicates that no fossil Anthracinae (in his interpretation, Anthracinae and Exoprosopinae) were found in extensive collections of fossil Bombyliidae from the Miocene Florissant shales of Colorado. He postulates that this group arose in the Old World and migrated to North America during or after the late Miocene. This agrees with my interpretation.

Although argentatus is a species adapted to northern climates, as its ancestor presumably was, the greatest diversification of the group has taken place in tropical and subtropical areas. The adaptation of the ancestral stock to tropical and subtropical forests probably took place during and after the first glacial period of the Pleistocene. As the climate gradually cooled during the early Pleistocene, the ancestral population was driven southward. According to Sears and Clisby (1955), spruce (Picea sp.) grew in the area of Mexico City during the most recent glacial period, which indicates that more temperate coniferous forests (such as those to which argentatus is presently adapted) may then have extended south into Central America, and probably during the previous periods. If this were the case, the ancestral population probably migrated as far as southern Mexico or Central America during the first glacial period. As the boreal forest retreated during the first part of the first interglacial period, small populations of flies would have been isolated on mountaintops where they would have been under strong selective pressure to adapt to the warming environment. As the isolates adapted to the new environment they would have been free to disperse throughout the tropical and subtropical areas from southern Mexico to southeastern Brazil.

After their dispersal during the first part of the first interglacial period, the population would have been split into three segments by the inundation of the Isthmus of Panama and the separation of the tropical forest in southeast Brazil from that around the Amazon Basin at the height of the interglacial period (Figure 1).

One of these segments, probably that in northwestern South America, may have evolved to the luctuosus complex. Anthrax luctuosus and cathetodaithmos are well-defined species with a strong resemblance in the structure of the male genitalia to argentatus, but the broad wings with a distinctive pattern and the structure of the female genitalia indicate that there is no close relationship with any other species of the cephus group. The two species probably were derived from populations isolated by an inundation of the Isthmus of Panama and since have become partially sympatric in Central America and northwest South America (Figure 3). At present, luctuosus has expanded over a wide range of tropical habitats.

The segment of the ancestral population isolated in southeast Brazil may have evolved to the present species hylaios. Like the luctuosus complex, hylaios shows no close relationship to other species of the cephus group, which may indicate that it was isolated early in the history of the group. This species has not expanded its range beyond the Serra do Mar of southeast Brazil.

The third segment of the ancestral population, probably that in southern Mexico, apparently gave rise to most of the remaining species of the cephus group. After expansion of its range during the second glacial period, this population would have been split at the Isthmus of Panama and south-central Brazil during the second interglacial period into three populations, one giving rise to the analis complex in southeast Brazil, the second to the argyropygus complex in northwest South America, and the other to the cephus complex in southern Mexico.

The third glacial period with the accompanying cool, wet climate and low sea level probably allowed the ancestral population of the cephus complex to disperse throughout southern Mexico and northwestern South America, and into southern Brazil. During the first part of the following interglacial period the ancestral population also migrated into eastern North America. At the middle of the period, the four populations were isolated in these areas and developed into distinct species (Figure 5). The relationship of these four taxa has not changed greatly since they were isolated, although the expansion of forests during the last glacial period has made possible the expansion of the ranges of the Neotropical species to their present locations. Although cephus and aterrimus are superficially similar, their basic characters show no closer relationship than with the other species of the complex.

During the third glacial period, the pre-argyropygus population probably migrated north into Mexico and southeast to the coast of Brazil, and one part apparently moved up the Lesser and Greater Antilles to the island of Jamaica where it has evolved into the species delicatulus. With the isolation of the Mexican population during the third interglacial period, and the expansion and contraction of the range of the population during the fourth glacial period and up to the present, the species costaricensis, snowi, and pluricellus have been disassociated. The species laticellus may have reached Arizona during the first part of the third interglacial period, after which it was isolated (Figure 4).

Toward the end of the third interglacial period, the pre-argyropygus ancester again expanded into Mexico, Arizona, and eastern North America. The recent warmer and drier climate has resulted in the isolation of argyropygus painteri in Arizona and the semi-isolation of argyropygus albosparsus in southern Mexico, as well as the restriction of the range of argyropygus argyropygus to include eastern United States, and the Gulf coast of Texas and eastern Mexico. Anthrax angustipennis remains in northwestern South America and has expanded into southeastern Brazil (Figure 6).

The exact relationship between angustipennis, macquarti, and repertus in South America is open to question. Whereas the structure of both the male and female genitalia indicate a close relationship between macquarti and repertus, the reduced anal margin of the wing indicates a close relationship between macquarti and angustipennis. Also, a specimen has been studied which appears to be an intermediate between the last two species. A possible explanation is that macquarti was isolated from angustipennis in southeast Brazil during the third interglacial period. Anthrax austrinus, a close relative of macquarti, occurs in south Brazil. It may have been separated from macquarti by the cold uplands in southern Paraná during the last glacial period (Figure 5).

The analis complex probably evolved from an ancestral form during the second interglacial period in southeastern Brazil. During the third glacial period it expanded into Central America and, during the third interglacial period, into North America. Also, it apparently has migrated by way of the Bahama Islands from Florida to the West Indies, probably during the fourth glacial period. During the third interglacial period, the North American population was isolated from that in northwestern South America and evolved to the present species, analis. Apparently, the population in Florida was also isolated for a short time during the third interglacial period but was reunited with resulting hybridization giving rise to the forms now recognized in the southeastern United States. The West Indian population has evolved to funebris. In South America, the northwestern population was apparently isolated from that in eastern Brazil by the restriction of forests in south-central Brazil. The northwestern population gave rise to gideon, the southeastern population to repertus. It is not clear how clinopictus and repertus were separated. Perhaps the pre-repertus form became adapted to a dry habitat, as it is now, and was semi-isolated in northeastern Brazil, whereas clinopictus remained in the forest area of south-central Brazil. At any rate, the two species are distinct because they are now at least partly sympatric. From the last glacial period up to the present, gideon has expanded its range into southern Mexico and the coastal forest of southeast Brazil, while repertus has expanded into grassy or semidesert areas from southern Brazil through the Guianas to Central America and along the Pacific coast southward into Peru. Anthrax analis has expanded its range throughout the United States and northward far into Canada. In southern Mexico, it is sympatric with gideon and intermediates have been seen from one locality (Figure 2).

The separation of argentatus and nitidus probably took place during the third interglacial period. When the pre-argentatus population retreated from Arizona during this time, a small isolated population probably became adapted to the desert habitat and has expanded to become allopatric to argentatus as it is at present.

In addition to the above species, four anomalous species are known from only one locality. Anthrax inaquosum is known from Mossoró, Rio Grande do Norte, Brazil. It apparently is not closely related to any other species in the group. It may have had an origin separate from that of the cephus group in South America.

Anthrax innubilipennis is known from only three males collected at Iguala, Guerrero, Mexico. It is most closely related to delicatulus from Jamaica. The origin that would best fit into the evolutionary scheme given above is from Jamaica into southern Mexico by way of Costa Rica or Nicaragua during the fourth glacial period (Figure 4).

Anthrax koebelei is known from only three complete reared specimens labeled “Arizona.” The male genitalia are most similar to the analis complex, and koebelei may have been derived from an “off-shoot” of the pre-analis population during the third interglacial period.

Anthrax xanthomeros is known from only one specimen collected at Benque Viejo, British Honduras. It seems to be a rather primitive species with no close relationship to other taxa.
bibliographic citation
Marston, Norman L. 1970. "Revision of New World species of Anthrax (Diptera: Bombyliidae), other than the Anthrax albofasciatus group." Smithsonian Contributions to Zoology. 1-148. https://doi.org/10.5479/si.00810282.43