Polyrhachis (Myrma) atalanta Wheeler, 1922, new species
Creators: name: Wheeler, W. M.
Publisher: name: Zenodo
Year: 1922
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Formicidae
Polyrhachis
Polyrhachis atalanta

description: Polyrhachis (Myrma) atalanta, new species
Text. Figure 71
Female.- Length somewhat less than 8 mm.; anterior wing 12 mm.
Head distinctly longer than broad, a little broader behind than in front, only moderately convex above, the portion behind the eyes short, with straight, scarcely marginate occipital border, the posterior corners rounded but distinct, the cheeks very feebly convex. Eyes large, prominent, somewhat less than hemispherical. Mandibles rather convex, with six coarse teeth- Clypeus convex, only moderately carinate. about twice as broad as longi its anterior border entire, nearly Straight. Frontal area large, triangular: frontal carinas approximated in front, very strongly sinuate and widely separated behind, the greatest distance between them being equal to their distance from the lateral borders of the head. Antenna; long, the scapes distinctly enlarged and slightly deflected at. their tips, reaching about half their length beyond the posterior border of the head. Pronotum with two rather large, acute, diverging teeth, which are triangular, as long as broad at their base, and somewhat flattened. Mesonotum evenly convex, as broad as the head through the eyes, and as long as broad. Scutellum rather flat. Epinotum with rounded, convex base, which is about three-fifths as long as broad, measured along the sides, where it is bluntly marginate, its posterior corners with two recurved teeth, which are somewhat smaller and more slender than those of the pronotum, about, twice as long as the width of their bases, directed outward, barkward, and slightly upward. They are connected by a strong transverse carina, strongly curved forward in the middle and separating the base from the declivity, which is very much shorter than the base and very concave. Petiole as bniail us high, very thick and strongly convex anteriorly and posteriorly, its anterior surface somewhat truncated below, its superior border bearing four broad, flat spines, very slightly incurved, and more strongly curved backwards especially tit t heir t ips. The inner pair is somewhat longer and broader than the outer. Gaster oval, the first segment not marginate on the sides and not. very strongly truncated anteriorly. Legs rather stout, tibia; distinctly constricted at their bases.
Rather shining throughout and strongly sculptured as follows: Mandibles sharply and rather coarsely striatopunct.ate; front and posterior portion of the head sharply longitudinally rugose: the ruga- on the clypeus, cheeks and sides of the head, however, irregular and more or less vermiculata. Upper surface of pronotum, mesonotum, scutellum, and base of epinotum sharply longitudinally rugose like the back of the head, the base of the epinotum more strongly. On the pronotum the ruga.diverge from the middle of the anterior border and there is also a similar, though less pronounced, tendency in the mesonotal rugae; those on the epinotum are strongly arcuate, on the sides. Sides of the thorax punctate-rugulose; anterior and posterior surfaces of the petiole transversely and rather vermiculately rugulose, except the tips of the spines, which are smooth and shining, as is also the declivity of the epinotum. Gaster very finely and densely punctate; the anterior two-thirds of the first segment longitudinally rugulose, the rugules being sharp and occasionally anastomosing. Scapes and tibise coarsely rugulose, with large, elongate piligerous punctures.
Hairs silvery white, long, erect, abundant, covering the whole body, except the apical half of the funiculi; as conspicuous on the scapes, cheeks, and legs as on the thorax and gaster. Pubescence grayish, very fine, short, and appressed, distinct only on the gaster, where it is sufficiently abundant to dim the surface but not to conceal the sculpture.
Black; palpi, tibial spurs, and terminal joint of tarsi testaceous; tips of funiculi and wings brownish, the latter with pale brown veins and dark brown pterostigma.
A single specimen from Stanleyville (Lang and Chapin), without further data. This species is evidently very closely related to Ern, Andre's P. sulcata, which is also known only from the female. This form, however, according to the description, is slightly larger (9 mm.), has the mandibles very superficially and almost indistinctly rugose, the eyes are more than hemispherical; the rugae on the epinotum are described as "transversalement arquees"; the petiole is higher than broad and the pilosity is duller. P. atalanta may eventually prove to be merely a subspecies of sulcata.
description: Published as part of Wheeler, W. M., 1922, The ants collected by the American Museum Congo Expedition., pp. 39-269 in Bulletin of the American Museum of Natural History 45 on pages 263-264