Andricus breviramuli, n. sp.

[Photos of this gall appear on page 6 of the pdf]

Gall (Figs. 3-4).Galls in the terminal part of twigs. Immature galls green, with a smooth, slightly shiny surface. Mature galls club-shaped, green to brown, with wrinkled surface, polythalamous, 6 to 10 cm long, with an average length of 4.8 cm (n = 30). Basal part narrow (7.6 mm diameter) while the distal part is broader (9.2 mm in diameter), the final third of the twig swelling sometimes to 14 mm in diameter. Internal tissues of mature gall are hard and woody. Larval chambers are oval (1 mm long x 2 mm wide) and 4 to 20 per gall aligned along the main axis of the twig.

Host Quercus laeta Liebm. (section Quercus of Quercus).

Distribution. México (Santa Fe, Delegación Cuajimalpa, DF, México City).

Biology. Only the asexual females are known. Adults emerge in late winter and early spring, when new shoots are starting to grow.

Etymology. Related to damage to host branches.

Andricus breviramuli Pujade-Villar, 2014
Andricus breviramuli Pujade-Villar, In Pujade-Villar et al.
(2014a: 98)

Gall (Figs. 3a-b). Plurilocular, located on the terminal branches. Immature galls are green, with a smooth and slightly shiny surface; mature galls are mace-shaped, green to brown, with a wrinkled surface, 6 to 10 cm long. The basal part is narrow (7.6 mm in diameter) while the distal part is wider (9.2 mm in diameter); the final third of the twig sometimes swells up to 14 mm in diameter. The internal tissues of the mature gall are hard and woody. The larval chambers are oval (1 mm long x 2 mm wide), between 4 to 20 chambers aligned along the main axis of the twig.

Hosts. Quercus laeta (Quercus section).

Biology. Species known only for the asexual generation. Adults emerge between late March and early April, when new shoots begin to grow.

Distribution. Only known from Santa Fe (Mexico City).

Comments. Andricus breviramuli was considered from the moment of its description as a harmful species on Q. laeta in the southwest of Mexico City. The gall wasps can kill and distort the branches of individual stressed trees. After the emergence of the adult wasp, the tissues where the larval chambers are located die, but the basal part remains alive so the branch will produce new shoots. However, multiple repeated attacks by the wasp can kill branches and distort and reduce the growth of an entire tree. Currently, the attack in Santa Fe is less virulent than 6 years ago; there are still attacks, but the populations are less numerous so the impact of their presence is not as noticeable as years ago.