Anthrax aterrimus Doleschall 1858

Anthrax aterrimus (Bigot)

Argyramoeba aterrima Bigot, 1892, p. 349 [Argyramoeba].

Anthrax aterrimus.—Painter and Painter, 1962, p. 72.—Krombein, 1967, p. 400.

Argyramoeba cephus.—Osten Sacken, 1877, p. 243.—Coquillett, 1894, p. 95.—Johnson, 1895, p. 325 [part] [not Fabricius, 1805; misidentification].

Spongostylum cephus.—Aldrich, 1905, p. 222 [Spogostylum] [not Fabricius, 1805; misidentification].

Spongostylum slossonae Johnson, 1913, 55.—Cole, Malloch, and McAtee, 1924, p. 186 [Spogostylum].

Anthrax slossonae.—Brimley, 1938, p. 341.

MALE.—Integument entirely black or legs and genitalia reddish brown; integument generally grayish and brownish pruinose, margins of eyes and lower part of occiput silvery pruinose. Setae and scales on front black; face with black setae extending up to antennae, few white setae along oral margin. Setae on occiput black, scales black above, white below; fringe of pile on posterior margin black exteriorly and white interiorly above, white below. First antennal segment slightly longer than apical width; second segment globular; base of third segment flattened mesolaterally, tapering gradually to styliform part which is about equal to base in length; style one-half to three-fourths as long as styliform part of third segment (Figure 96).

Setae and scales on mesonotum and scutellum mostly black; a few white or brown, threadlike scales in front of bases of wings and apically on scutellum. Sternopleuron, mesopleuron, and anterior half of pteropleuron with fine black setae and threadlike white scales; some white pile and some brown and/or black scales, setae, and hairs dorsally on mesopleuron and pteropleuron. Pile on prosternum, propleuron, and anterior margin of mesonotum white or with some brown and black hairs intermixed; postalar tuft of pile black with some hairlike white scales basally. A few white hairs behind spiracle; a few black setae and hairlike white scales anteroventrally on hypopleuron. Fore coxa with white scales and hairs and black setae; middle and hind coxae with mixed black and white scales and black setae.

Wing (Plate 4d) entirely pigmented with brown or black, discs of apical cells sometimes subhyaline, apical part of wing rarely entirely subhyaline. Stigmatic area lightly pigmented, calypter lightly pigmented, fringe of hairs brown. R–m crossvein located one-third to two-fifths of way from base to bifurcation of vein M1+2; contact of cells 1M2 and Cu1 slightly shorter to slightly longer than base of cell Cu1. Vein R4 with long spur at its basal angle.

Scales on legs entirely black; scales on hind tibia often semirecumbent. Middle femur with complete row of macrochaetae anteroventrally and one to several postmedial bristles on anterior side; posterior femur with complete rows of macrochaetae anteroventrally, posteroventrally, and anterodorsally. Posterior tibia with double row of macrochaetae anterodorsally.

Pile on lateral margins of first abdominal tergum white; terga two through four with dense black pile laterally, a few white hairs posteriorly on fourth tergum. Posterior margin of first tergum, discs of terga two through four, and medial part of five and sometimes six with sparse black setae and linear black scales. Remainder of posterior terga with dense, overlapping, posteriorly produced, silvery-white scales. Hairs and scales on venter sparse, black, white, or mixed, the white usually predominating anteriorly, the black posteriorly.

MALE GENITALIA (Figure 56).—Gonocoxites long, apical part narrow, dorsal margins tapering to ventral margins apically; apices rounded and slightly curved mesally in ventral view, folded inward mesally to form deep mesal sulcus; long setae covering entire surface almost to base. Basal segment of gonostylus oblong in lateral view, extending to base of distal segment, with dense tuft of setae apically; distal segment small, ovoid in ventral view, with short, truncate process extending outward near the apex and twisted apically, entire segment except styliform part with fine short setae. Apex of epiphallus flattened dorsoventrally, apex bluntly angled in dorsal view; a short, sharp recurved lobe present on each side midway between junction of dorsal bands and apex; dorsal bands proximate mesally, with some setae before junction. Base of aedeagus small and narrow, almost tubular, tapering slightly to junction with ventral bands below lateral lobes of epiphallus.

FEMALE.—Similar to male. Pile and scales on thoracic pleura usually more predominantly white. Fore and middle femora and tibiae usually with white scales posteriorly; hind femur sometimes with a few white scales posteriorly at base. White scales and hairs on abdominal venter usually restricted to first three sterna. Silvery-white scales apically on abdominal terga restricted to posterolateral margins of five and six.

FEMALE GENITALIA (Figure 75).—Tenth tergum with about 27 spines on each side. Ventral arm of ninth tergum enlarged apically, irregularly margined. Dorsomedial corner of sclerite on each side of gonopore greatly produced dorsally as a rounded lobe; lateral arm short, broad and emarginate apically, extending posterolaterally; ventral arm broad evenly margined and twisted mesally on lower half. Each duct of spermathecae greatly elongated, about 6 times longer than bulb; first section very short; second section about two-thirds as long as apical section which is about 3.5 times longer than bulb and gradually expanded from base to apex; bulb slightly longer than wide, rounded, not well defined from duct.

DISTRIBUTION.—Anthrax aterrimus occurs in forested areas in southeastern United States as far north as Connecticut and the southern tip of Illinois, and as far west as central Texas (Map 18).

TYPES.—According to Painter and Painter (1962) the type of Argyramoeba aterrima, a female rather than a male as stated by Bigot, is in the Bigot collection of the British Museum. It is heavily draped with fungus but otherwise in good condition. It carries the label “Argyromoeba aterrima n. sp. Inédit. Quincy Juin 1886 J. Bigot Baltimore.” Bigot’s description agrees well with typical specimens of the species, including the paratype series of slossonae (Johnson).

The types of Spongostylum slossonae are in the Museum of Comparative Zoology at Harvard University. The entire series from which the species was described, with the exception of the types, has been examined by the author. The type-locality is Cumberland Gap, Kentucky.

BIOLOGY.—Anthrax aterrimus was recorded (as cephus Fabricius) as being “bred from the nest of a Mud-wasp in Texas, forming tubes of clay five or six inches long, pasted together like organ-pipes,” very probably Trypoxylon politum Say (Hymenoptera: Sphecidae), by Osten Sacken (1877). An additional specimen in the collection of R. H. Painter carries the label “bred from mud dauber nest.” Krombein (1967) reared this species from nests of Trypargilum striatum (Provancher), T. collinum rubrocinctum (Packard), T. clavatum, Isodontia auripes (Fernald) (Hymenoptera: Sphecidae), Euodynerus megaera (Lepeletier), Monobia quadridens (Linnaeus), and Ancistrocerus spinolae (Saussure) (Hymenoptera: Vespidae).

MAP 18.—Distribution of Anthrax aterrimus.

Anthrax aterrimus (Bigot)

Twenty-six pupal skins of this species from the National Museum of Natural History have been studied (see table). According to Krombein (1967), they were taken from nests of Trypargilum striatum (Provancher), T. clavatum (Say), T. collinum rubrocinctum (Packard), and Isodontia auripes (Fernald) (Hymenoptera: Sphecidae); Euodynerus megaera (Lepeletier), Monobia quadridens (Linnaeus), and Ancistrocerus spinolae (Saussure) (Hymenoptera: Vespidae). An additional specimen was reared from a “mud dauber wasp.”

Integument of pupa yellowish hyaline with yellow setae and reddish brown, black-tipped tubercles and spines. Anterior cephalic tubercle straight, tapering, with dorsomesal and ventrolateral ridges distally, without well-defined ridges basally; medial tubercle formed on or slightly outside a line between anterior and posterior tubercles, closer to posterior tubercle, slightly shorter than anterior tubercle, acuminate, with sharp ventrolateral ridge connecting to posterior tubercle; posterior tubercle short, slightly curved dorsomesally with sharp dorsal, ventromesal, and ventrolateral ridges. Facial sclerite about five and a half times longer than its narrowest width, with shallow, rounded emargination posteriorly. Anterior facial tubercles short, broad, anteroposteriorly flattened, tapering slightly to broadly rounded apices; posterior facial tubercle not developed.

Sixth and seventh terga with small spines between setae. Eighth tergum with two spines on each side, one on each side of dorsolateral tumidity (lateral spines sometimes bifurcate); setae absent on tergum (1 seta present adjacent to lateral spine on one specimen).

Medial process on ninth tergum short, broad to narrow basally, acuminate to sharp or narrowly bifurcate apex. Each anal tubercle three to five times longer than medial width of one tubercle, straight, separated mesally one-fourth to one-third of width of one tubercle; each tubercle with sharp dorsal and ventral, unconnected denticles near base; mesal margin with broad, sharp, preapical ridge, forming dorsal and ventral denticles, and sharp ventral denticles about one-third of distance to apex; each tubercle tapering outward from preapical ridge to sharp tip.

The pupae of A. aterrimus and pluricellus are quite similar. Differences are discussed under the latter species.