Transversal section-obj x10 - darkfield  - chlorophyll "palisade" parenchyma in tight bundles. The small dark disks in the inferior epidermis are stomata.	with polarized light a long bundle of vessels could be seen

The hardness of the leaf made it difficult to obtain the sections, mainly because at first I tried using razor blades of the "thin" type. Changing to blades of normal thickness, the sections were possible without problems. 

one minor vascular bundle, obj x10, darkfield	the minor inferior bundle with the x40 obj

spongy (aerophyll) parenchyma, obj x40, brightfield	a stomatal chamber, in the spongy parenchyma

A section of the petiole from a young leaf. It was recorded as 6 individual pictures of 640 x 480 px. The individual pictures were stitched in PhotoPaint and the mosaic was reduced to 500 px to be inserted here.

But most interesting was that many of the leaves showed a surface marked by innumerable galls that protruded from both faces of the leaf and which I thought could either be caused by fungi (but not very probable due to their structure, which were small volcanoes in both sides of the foliar lamina) or, almost certainly, by parasitic insects.
 

There is a large pith in the petiole, surrounded by a continuous "stela" with a lot of small vascular bundles. Cortical parenchyma and cholenchyma are reduced to a narrow strip.	A sector of the petiole seen under the 40x objective. Notice the regular cells in both pith and cortical parenchyma. The blue 'halo' which are short hairs covering the surface.

It was a magnificent opportunity to try the mesotome to aid an investigation of vegetal pathology. But although I do not doubt that it will have utility on other occasions, I had to give up after breaking two instruments. Dishonorable failure!

I could only cut the incipient galls in young leaves, which are where the insect apparently deposits its eggs.

A better view with the 40x of a similar sector to the one shown above with the 10x. This time with a blue-white Rheinberg filter.  You see the small xylem and huge phloem system in the vascular bundles, the cambium as a dark strip, the clear cortical parenchyma, and the mostly yellow chollenchyma.	A view with the 40x objective of the chollenchyma to show the sclerified walls of the cells, and the row of small crystals (spherical aggregates of calcium oxalate) in the epiderm. Short "hairs" cover all the surface of the petiole.

 The completely developed galls have a fibrous structure and a hard ligneous consistency that ended up defying even my better scalpel. Finally, with it sharpened very well for each cut, I managed to discover not only the anatomy of the galls in longitudinal section, but also its inhabitants. 

this drew my attention to the parasite	a closer view from the underside of the leaf

With incident light we can see in the two images below right and with a magnification of x25 the structure of the galls in a vertical section.

the upper side of the leaf showing that the morphology of the galls varies	A cut through the gall, showing its relation with the foliar blade. In the dark sector at left is a larva. See below.

one larva discovered by the scalpel x4 objective	a pair of contiguous galls - the right-hand one has two pupae

the two pupae seen with the x4 objective - incident light

In one empty gall I found the shed skin of a pupa, and at once verified that the guest was a dipteran. I looked for the possible identity on the Internet. The only work that I found is dated 1970 and it identifies a dipteran of the Cecidomyidae family, from a group called "gall midges", with a North American species (from Florida, specifically) known as Ctenodactylomyia watsoni, whose nutgalls and maker can be seen in the following pictures taken from Circular 97 (1970) of the Florida Department of Agriculture & Consumer Services. 

The galls of Ctenodactylomyia watsoni, parasite of Coccoloba from Florida, EEUU. At upper left, one of the galls was broken up to show the larvae. The shape, structure and exit openings are very different from the Cancún material. In the lower images two views of the adult midge.

 Although I do not doubt that the genus of the Cancún midge is the same one, it seems to me that the shape of the galls and the double incubation chamber shows that it must be a different species, in spite of the relatively short distance between the Florida peninsula and the Island of Cancún.

To break two mesotomes can also have its compensations.

NOTES:

 Comments to the author, Walter Dioni , are welcomed.