Sericomyrmex wheeleri, Neal A. Weber, University of North Dakota, 1936

Neal A. Weber, University of North Dakota, 1936, The biology of the fungus-growing ants. Part. I. New forms. 1, Revista de Entomologia 7, pp. 378-409 : 396-397

Sericomyrmex wheeleri , sp. nov. (Fig. 8)

Worker: Length 2.7-3.8 mm. - Head, excluding mandibles and occipital spines, slightly broader than long, distinctly but broadly impressed on the posterior border, occipital spines long, longer than the diameter of eyes. Lateral tubercles, eyes, scrobes, scape, and clypeus as in the female. Terminal antennal joint proportionately longer, being equal in length to joints 7-9 and only a little shorter than joints 2-5 of funiculus. Thorax in profile as illustrated (Fig. 8). Seen from above the basal surface of epinotum bears two irregular and slightly diverging low ridges terminating in distinct spines. Dorsum of petiole and postpetiole broadly impressed. First gastric segment at the base with shallow medial impression, laterally with distinct ridges.

Mandibles shining, with a few pits bearing hairs along the cutting margin and with smaller punctations more irregularly dispersed; surface, chiefly at the base, with striae. Rest of body opaque, rugulose; gaster coarsely reticulate. - Pilosity only partly obscuring integument. Clothed in reclinate, stiff hairs which appear grayish distally, blackish at the base. Pubescence yellowish, sparse, except on terminal joints of funiculi. Most specimens covered with a grayish bloom. - Dark ferruginous, appendages lighter distally.

Female (dealate): Length 4.9 mm. - Head, excluding mandibles and occipital spines, slightly broader than long, feebly impressed on posterior border. Occipital spines long, equal in length to diameter of eyes. Distinct lateral tubercles just beneath base of occipital spines. Eyes moderately convex, situated in front of middle of head. Antennal scrobes distinct, extending to base of occipital spines, bordered laterally by carinae. Clypeus convex, broadly notched in middle. Antennal scapes extending to apex of occipital spines, distal diameter twice that of proximal diameter. All antennal joints longer than broad; terminal joint shorter than joints 7-9 taken together and longer than joints 2-4 of the funiculus. Epinotum with pointed tubercles. Petiole, postpetiole, and first gastric segment with dorsal median impressions, the latter segment with distinct carinae on the sides. Pilosity as in the worker. Color darker.

Described from a colony containing several queens and many workers taken by myself August 29, 1935, several miles from the Forest Settlement, Mazaruni River, British Guiana. The nest entrance was a mere hole partly formed by cutting out a segment of the margin of a dead leaf. The nest structure, consisting of three chambers with partly pendant, partly sessile, fungus gardens will be described in a subseqent paper.

This species is dedicated to the late Dr. W. M. Wheeler whose important studies on ants at Kartabo Point, a few miles distant from the type locality, have been of great help in learning the rich neotropical fauna.

The species is close to S. opulenta Mann from Honduras. Three cotypes of Dr. Mann's species in the Harvard Museum of Comparative Zoology were compared with workers of this species. The workers of 5. wheeleri are slightly smaller. Occipital, mesothoracic and epinotal spines are much higher. Proportions of the petiole and postpetiole are different. Entrance to the type colony of opulenta was a turret 6 inches high, to wheeleri a mere hole in the forest floor. Only one fungus garden was found in opulenta and, as it was 4-5 inches in diameter, the colony was evidently mature.