Plagiotrochus britaniae Barbotin, 1985

Pujade-Villar, Juli, Villemant, Claire & Andreï-Ruiz, Marie-Cécile, 2000, Cynipidae associated with Quercus collected in Corsica with the description of a new Plagiotrochus species (Hymenoptera, Cynipoidea), Zoosystema 22 (4), pp. 835-846 : 839

Plagiotrochus britaniae Barbotin, 1985

MATERIAL EXAMINED. — Vallée du Fango. Yellow pan trap, 7-14.V.1993 (R2/DA/S 3), 1 ♀ ( UB); ( R2 /DA/ C 2) , 1 ♀ ( MNHN); ( R2 /DN/C 2) , 1 ♀ ( MNHN); ( R2 /SE/C 3) , 1 ♀ ( MNHN) ; 14-21.V. 1993 (R3/DA/S 3), 1 ♀ ( MNHN); ( R3 /SW/C 2) , 1 ♀ ( MNHN) ; 21-28.V.1993 (R4/SE/C 1), 1 ♀ ( MNHN); ( R4 /SW/C 1) , 1 ♀ ( MNHN) ; 4- 11.VI.1993 (R6/DN/C 32), 1 ♀ ( MNHN) .

REMARKS

Althought this species probably has a circummediterranean distribution, it has thus far only been collected in Andorra, Algeria, Spain and France (Barbotin 1985; Nieves-Aldrey 1989; Pujade-Villar 1997).

The galls, 1 mm in length, are formed in Q. ilex and Q. coccifera buds and are partially covered with the bud’s scales, or can be regrouped in more visible and sometimes coalescent clusters of two to four galls in the aborted acorn cups of Q. coccifera . Information concerning the biology of this species is contradictory. Barbotin (1985) reports that in Bretagne ( France), where Q. ilex was introduced, two successive thelytokous generations occur; in this case the agamic form is absent. Barbotin reared males from Algeria where Q. ilex is aboriginal. A similar feature resulting from the moving of cynipid populations was recently described for Plagiotrochus species on Q. suber in North and South America (Pujade- Villar 1998). The agamic form is unknown but could be P. coriaceus (Mayr, 1882) , according to Pujade-Villar & Ros-Farré (1998) because the females are morphologically very similar and the two forms may only be distinguished by their gall (Nieves-Aldrey & Pujade-Villar in press). As for the other Plagiotrochus species it seems impossible to determine without experiment which is the alternating form. The Barbotin’s results in Bretagne make such experimentation indispensable in the case of P. britaniae .