Nothomicrodon aztecarum Wheeler, 1924.
Wheeler, W.M. (1924) Two extraordinary larval myrmecophiles from Panama. Proceedings of the National Academy of Sciences, USA 10, 237-244. [1924.06.15]
From original description (Wheeler 1924).
"I found suspended from the branch of a large tree a rather small carton nest of the typical Azteca trigona Emery. It was about a foot broad through its base and about ten inches long. I hastily cut off the greater portion of the structure and enclosed it with its infuriated inhabitants in a cloth bag, which was taken to Mr. Zetek's laboratory in Ancon and on the following day placed in a large jar with some chloroform. I was then able to break the nest into small fragments and to examine its contents in comfort. Besides thousands of Azteca workers and their brood I found in the chambers a single small wingless Braconid myrmecophile and more than a hundred small, hard, rather shining, dark brown, lenticular objects which I at first took to be seeds. They were scattered through the chambers of all parts of the nest and were lying freely among the brood. More careful examination showed that they were Dipteron larvae, all in the same apparently adult stage of development and of very nearly the same size (3.5-4 mm. long, 2.6-2.8 mm. wide). Unfortunately none of these larvae recovered from the effects of the chloroform so that I was unable to rear them.
The body consists of a larger, broad, flattened carapace-like, suboctagonal abdominal and a smaller, narrow, anterior cephalothoracic portion, which can be drawn into the abdomen. The dorsal surface of the latter is feebly convex, with two rather deep, transverse grooves near the middle and a small rounded tubercle at the posterior end. The ventral surface is flat, with a pair of longitudinal, lateral furrows, or impressions which widen posteriorly and nearly meet at a small circular area and pit, which represent the anus. The anterior portion of the abdomen above is divided by T-shaped sutures into a median triangular plate and two lateral suboblong plates, each of which bears a clearer, thinner, slightly elevated, elliptical area which evidently represents the point of future extrusion of the prothoracic stigmal horn of the pupa. The T-shaped sutures, like the similar structures in the late Microdon larva and puparium are, of course, a prearrangement for the emergence of the adult fly. The anterior portion of the body consists of the retracted pseudocephalon with the mouth-hooks projecting from its orifice but without distinct traces of antenne, and three short segments representing the thorax. The first of these bears a pair of cylindrical appendages, the prothoracic spiracles. The remaining-segments bear no appendages and are readily telescoped into one another when the anterior portion of the body is retracted. The dark brown abdominal integument is very tough and leathery, neither thinner nor more flexible on the ventral than on the dorsal surface and consists of a beautiful mosaic of usually hexagonal chitinous plates, which tend to disintegrate when boiled in caustic potash. On both surfaces very near the posterior end of the body there are two transverse areas, each consisting of a series of narrow, elongate plates. The dorsal surface also has a number of scattered but regularly arranged sense organs, each lying between two contiguous polygonal plates. These organs seem to be Hicksian sensillae and to be the same as those seen in many other Dipteron larvae, notably in Itonidae (Cecidomyidae), Syrphidae (Microdon) and Lonchopteridae. The integument*of the pseudocephalon and thoracic segments is much thinner, more yellowish and consists of smaller polygonal plates than that of the abdomen. The stigmal areas on the first abdominal segment are finely areolated. The posterior tubercle bears a pair of very small reniform stigma plates, separated by a slit-like structure, the significance of which is by no means clear. Each stigmal plate has four small triangular spiracular openings and in front of it lies a structure that seems to correspond to the small "circular plate" of many Cyclorrhaph Dipteron larvae. The cephalopharyngeal apparatus is so extremely small that I have been unable to obtain a satisfactory knowledge of its structure. The internal structure has not been studied".
The name Nothomicrodon is based on an unusual larva found in the carton nest of the ant, Azteca trigona. Shannon (1925: 213) without comment placed Nothomicrodon as synonym of Microdon. These larvae have none of the characteristics of Syrphidae and probably belong to another family, perhaps, Phoridae. The species has not been seen since the original collection was made (Cheng and Thompson 2008).
unless otherwise stated