Myrmicocrypta spinosa, 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 : 382-383

Myrmicocrypta spinosa , sp. nov.

Worker: Length 3.4-3.6 mm. - Head, excluding mandibles, 1/4 longer than wide, occipital margin concave but broken medially by a pair of tubercles which represent medial extensions of irregular carinae crossing dorsal surface anterior to occipital corners, these latter produced in form of tubercles. Sides parallel, produced in front and back of eyes as slight convexities. Anterior clypeal margin convex, covering bases of mandibles when closed, posterior margins obliquely raised as teeth. Eyes small, hemispherical, a little closer to mandibular insertions than to occipital angles. Frontal lobes convex, reflexed to cover antennal insertions, developed posteriorly as irregular carinae which enclose a frontal area. Antennal scapes feebly sinuate, expanded towards distal 1/2, exceeding occipital angles by a distance equal to 2 1/2 times their distal diameter. All joints of funiculus distinctly longer than broad, terminal joint as long as joints 7-9 taken together. Mandibles with 7-8 teeth, gradually enlarging apically.

Pronotum with two distinct pairs of tubercles, a larger dorso-medial and a lateral pair. Mesonotum in profile with massive lateral pair of tubercles, sometimes truncate, two more medial and posterior pairs with acute apices and a pair of smaller and acute tubercles whose posterior base descends to the mesoepinotal impression; spaces between the tubercles concave. Basal surface of epinotum laterally with carinae which rise posteriorly to acute teeth. Basal and declivous surfaces enclosing an angle of about 60°.

Petiole pedunculate, node and peduncle of equal length, the latter rising smoothly and with flat dorsal surface. Postpetiole shorter than petiole, with flat ventral and slightly concave dorsal surfaces. Postpetiole from above with evenly convex sides and anterior margin; posterior margin straight, slightly wider than long. Anterior and posterior margins of first gastric segment slightly convex, distinctly longer than broad. Legs long and slender.

Head arid thorax opaque and shagreened, the former sparsely rugulose; gaster sub-lucid, finely punctate; mandibles and appendages sub-lucid, the former finely striate, the latter punctate. - Hairs of body squamate, sparse, on thorax only one or a few about projections, more abundant on antennal scapes and legs. - Ferruginous, borders of mandibles infuscated. In some specimens head and gaster are darker than rest of body.

Described from two colonies taken from the same log September 8, 1935, by myself about 23 miles west of Kartabu Point, British Guiana. The log was rotted and reclining against other trees in virgin swamp rain forest. Under the rotted bark about six feet above the ground was one colony and a few feet along the log was the other colony at a height of 8 feet. In this same log near one of the colonies was the nest of Apterostigma amiae , sp. nov.

A dealate female taken by myself August 20, 1935, near the Forest Settlement, Mazaruni River, B. Guiana probably belongs to this species. It was colleced as it wandered over the top of a fallen log near a Cyphomyrmex colony and was evidently seeking to find a suitable place in whidh to develop a fungus garden and colony independently. The insect is about 3.5 mm. long with coarsely sculptured integument which is opaque Ion head and thorax and shagreened, and is sub-lucid and finely reticulate on gaster. The color is grayish brown with more ferruginous appendages.