Anthrax pluricellus Williston 1901

Anthrax pluricellus Williston

Seven pupal skins of A. pluricellus have been examined (see table). These were taken by Rau from nests of Chalybion zimmermanni Dahlbom. (Hymenoptera: Sphecidae) (Rau, 1940). The specimens are in the collection of Dr. R. H. Painter and the National Museum of Natural History.

Integument of pupa yellowish hyaline with yellow setae and reddish brown black-tipped tubercles and spines. Cephalic tubercles (Plate 2F) evenly spaced, in a straight line; anterior tubercle of moderate length, compressed dorsoventrally toward apex, with poorly defined mesal and lateral ridges; medial tubercle nearly as long as anterior one, slightly bent forward, acuminate, with indistinct dorsolateral and ventromesal ridges, and sharp ventrolateral ridge connecting to posterior tubercle; posterior tubercle short, slightly curved anterodorsally, concave on anteromesal surface, with sharp anterolateral and posteromesal ridges and indistinct posterolateral ridge. Facial sclerite about eight times longer than minimum width, posterior end with broad, semicircular emargination; anterior facial tubercles flattened anteroposteriorly, bent forward slightly, broad, short, bluntly rounded apically; posterior facial tubercle undeveloped, represented by rounded node. Facial setae arising just anterior to level of anterior facial tubercles.

Spiracles a little above level of integument, with out distinct flanges; thoracic spiracle with about 12 sections, posteroventral ones reduced; abdominal spiracles with about ten sections, anteroventral ones reduced.

Sixth and seventh terga with numerous, small spines between setae. Eighth tergum with two spines on each side, one on each side of dorsolateral tumidities, additional small spines sometimes present; setae absent. Medial process on ninth tergum broad, low, sharply rounded apically. Anal tubercles (Plate 3F) about six or seven times longer than medial width, separated medially by one-fourth or less of width of one lobe. Each tubercle with dorsal and ventral, sharp denticles near base unconnected or joined by low, poorly defined ridge; mesal margin with sharp denticle ventrally about one-third of distance to apex and large mesal denticle about three-fourths of distance to apex; apex narrow, straight, and acuminate beyond preapical denticle.

The pupae of A. pluricellus, aterrimus, argyropygus argyropygus, and hyalacrus are quite similar and probably are typical of most species of the cephus group except for species closely related to analis. The pupa of koebelei seems to be intermediate between analis and the first four, sharing some common characters with each, as does the adult. The pupa of koebelei, and those of the first four, may be readily separated from pupae of all other species studied, except trimaculatus, by the presence of spines on the eighth tergum. A. trimaculatus may be readily distinguished by the high flange connecting the dorsal and ventral denticles on the anal tubercles.

In the cephus group, A. analis is unique in that it lacks spines on the eighth tergum, while koebelei is distinctive in that it has only one spine on each side, lateral to the dorsolateral tumidities. Other species have an additional pair mesad to the tumidities. In pluricellus, the anal tubercles are distinctly longer man in argyropygus, hyalacrus, and aterrimus, about six or seven times the medial width of one lobe rather than five times the medial width of one lobe or less. A. hyalacrus may be distinguished from pluricellus, argyropygus, and aterrimus by a pair of setae between the innermost spines on the eighth tergum. The setae are in a direct line between the dorsolateral tumidities rather than in front of them as on pupae of other groups. The cephalic tubercles of A. argyropygus are distinctive in that the medial one is set slightly inside a line between the tips of the anterior and posterior ones, whereas in pluricellus, aterrimus, and hyalacrus they are in a straight line or the middle one is set slightly outside the line.

Anthrax pluricellus Williston

Anthrax pluricellus Williston, 1901, p. 277 [pluricella].—Kertész, 1909, p. 51 [pluricella].—Painter and Painter, 1962, p. 79.

Exoprosopa capucina.—Rau, 1940, p. 594 [not Fabricius, 1805, misidentification].

MALE.—Body mostly black, tibiae and femora yellow; integument blue gray and brown pruinose; eye margins, face, and lower half of occiput white pruinose. Front with black setae and linear black and yellow scales; fringe of hairs on posterior margin black exteriorly, white interiorly above, white below. First antennal segment about as long as apical width; second segment globoid, slightly flattened apically; base of third segment flattened mesolaterally, narrower than second segment in lateral view, tapering abruptly to styliform part which is slightly longer than base and about 1.5 times as long as style (Figure 105).

Discs of mesonotum and scutellum with linear black scales; rust-brown scales broadly over anterior and lateral margins and in triangular patch posteriorly on mesonotum, and anteriorly and laterally on scutellum. Sternopleuron, lower half of mesopleuron, and anterior half of pteropleuron with black and gold setae, white and yellow scales, and sometimes a few black scales. Prosternum, propleuron, dorsal half of mesopleuron, and anterior margin of mesonotum with white pile, some black setae and hairs on last two areas. Postalar tuft of pile black, some white or yellow scales often present basally. Fore coxa with white bristles and gold scales. Hypopleuron bare; metapleuron with a few hairlike white scales behind spiracle.

Wing (Plate 4a) light brown with hyaline areas at apex and extending inward from posterior margin, pigment filling cells C, Sc, and R1, extending beyond base of cell R4 in cells R2+3 and R5, filling base of cell R4, and extending from cell R5, broadly across base of cell M1 and apex of cell 1M2 onto spurious vein in cell 2M2; extreme base of cell 2M2 and basal fourth of cell Cu1 pigmented; extreme apex of cell M and apical spot in cell 2A hyaline. Vein R4 angled basally, with a short spur; r–m crossvein at basal two-fifths of cell 1M2, vein R2+3 arising slightly basad; contact of cells 1M2 and Cu1 slightly shorter than width of base of cell Cu1; cell 1A punctiform apically; cell 2A not reduced, wider than cell 1A postmedially; alula reduced, posterior margin straight; a spurious vein extending from apical angle of m crossvein to posterior margin. Stigmatic area lightly pigmented. Calypter lightly pigmented, fringe of hairs white. Halter light brown, apical margin of knob yellow, base dark brown.

Bases of legs mostly with light-yellow scales, some black scales dorsally on femora at apex and dorsally on hind tibia. Middle femur with two or three macrochaetae anteroventrally toward apex; anterodorsal side of fore femur with a few weak macrochaetae; hind tibia with single row of macrochaetae anterodorsally.

Sides of first abdominal tergum with white pile, a large or small area of light or dark brown pile anteriorly; lateral margins of terga two through four with black pile, setae, and scales, numerous light brown hairs mixed with scales anteriorly on second tergum and posteriorly on terga two through four. Posterior margin of first tergum with sparse black or rusty-brown linear scales; discs of terga two through four and central half of five with linear black scales; rusty-brown scales present anteriorly on two and posteriorly on two through five; centers of terga six and seven with black scales anteriorly and rust-brown scales posteriorly. Sides of terga five through seven with patches of elongate, posteriorly produced, overlapping, lanceolate-truncate, white scales and with tufts of black and yellow setae and pile. Venter with fine white and yellow setae, and linear white and yellow scales, darkest posteriorly.

MALE GENITALIA (Figure 60).—Gonocoxites broad, dorsal margins broadly rounded to truncate apically in lateral view, apices broadly rounded in ventral view, medial sulcus not defined, setae sparsely distributed ventrally and along dorsal margin. Basal segment of gonostylus convex above in lateral view, with a few fine setae apically. Distal segment of gonostylus oval basally, somewhat flattened dorsoventrally with a broad mesal lobe in ventral view; styliform part curved outward, apex flattened apically; fine setae present dorsally and laterally at base. Apex of epiphallus broad, somewhat flattened dorsoventrally; dorsal part with a raised, basally projecting central lobe and truncate apex; lateral part with long, flat lobes projecting basolaterally. Dorsal bands meeting mesally, but not coalesced, with numerous short setae. Base of aedeagus large and bulbous, dorsal margin curving downward to junction with ventral bands below approximation of dorsal bands.

FEMALE.—Similar to male. White scales on posterior abdominal terga restricted to lateral margins of fifth segment.

FEMALE GENITALIA (Figure 83).—Tenth tergum with about 16 spines on each side. Ventral arm of ninth tergum slightly enlarged and undulate distally. Dorsomedial corner of sclerite on each side of gonopore produced dorsally as a dactylate lobe; lateral arm slightly broader than dorsal lobe and rounded apically; ventral arm narrow, tapering to apex which is evenly curved mesad. Each duct of spermathecae about as long as bulb; first segment very short; second segment about as long as third which is bent at about a right angle before expanding apically to bulb; bulb about 2.5 times longer than maximum width, tapering to junction with duct and with dark, slightly enlarged apical section.

DISTRIBUTION.—The specimens referred to by Rau (1940) as Exoprosopa capucina (Fabricius) have been studied by the author and are almost certainly A. pluricellus, since they agree closely with the description of the type given by Painter and Painter. These specimens were collected 40 km south of Ciudad Victoria, Tamulipas, Mexico. The type-locality is “Atoyac in Vera Cruz,” Mexico. The species probably occurs all along the eastern coast of Mexico east of the Sierra Madre Oriental and perhaps inland on the central plateau.

TYPE.—Painter and Painter (1962) state that the type of Anthrax pluricellus, a female rather than a male as Williston indicated, is in the British Museum. It is in good condition except that the hind legs, one middle leg, and the left antenna are missing. Williston (1901) placed this species in Anthrax (auctt.) (Villa Lioy) since he believed that the head, which had been glued on, did not belong to the body.

BIOLOGY.—The specimens referred to by Rau were reared from the nests of Chalybion zimmermanni Dahlbom (Hymenoptera: Sphecidae).