Sphaerotheras tanos (Kinsey) n. comb.

Biorhiza tanos Kinsey, 1937: 453.

[Attending to the morphological characters and the host plants, we consider there to be three species of Sphaeroteras in Mexico: S solita, tanos, and zinzala. We cannot exclude the possibility that, in the future, the color forms S solita and S tanos will be considered the same species. For the moment, other than color, these species are separated by the host plants in which their galls are found; thus, S solita produces galls on multiple species of Quercus (arizonica, chihuahuensis, deserticola, jaralensis, magnoliifolia, microphylla, rugosa, and undulata [should be undata?]), while S tanos has only one host on which S solita is not found (Quercus repanda). Sphaeroteras zinzala has been collected in two hosts distinct from the other two species of Sphaeroteras mentioned (Quercus intricata and pringlei).

The galls of the three species of Sphaeroteras from Mexico are indistinguishable. Kinsey (1937) mentioned that they are like those of B pulchripennis. They are characterized by being more or less circular, between 3-4.5 mm in diameter, being located in the lower side of the leaves sometimes in great numbers, being attached to the midrib or secondary veins, being yellow to light brown, having the surface smooth and glossy covered in a short pubescence easily rubbed off with a few short darker bumps, having the base more or less flat with a longitudinal depression corresponding to the point where it meets the leaf vein; the larval cell is eccentric, attached to the walls of the gall by fine white filaments.]

Biorhiza tanos, n. sp.
Agamic form

Gall. — Similar to that of B. pulchripennis. Light to medium brown in color (no darker); of medium size, up to 4.0 mm, averaging nearer 3.2 mm. in diameter.

Host. — Quercus repanda, the lowest dwarf oak of the area. Replaced on all the taller tree species in the region by B. stelis and B. tricosa.

Range. — Hidalgo: Pachuca, 7 N, 8700' (types). Mexico: Mexico City, 32 E, 10,6007 Mexico Citv, 20 S. 9400'

Apparently one species on the dwarf oaks throughout the mountains rimming the Valley of Mexico.

Life History. — Adults: March 6, 18, 24, 25, 23 Nearly all of the recorded emergence in the last week of March.

In the mountains rimming the Valley of Mexico, on the taller tree species of oak there are two species of the present complex: stelis at the northern end, and tricosa at the southern end of the Valley. Throughout the entire area there is one species, tanos, on the low dwarf oaks of the Q, repanda complex.