Synergini, Ashmead, 1896

Buffington, Matthew L., Forshage, Mattias, Liljeblad, Johan, Tang, Chang-Ti & Noort, Simon van, 2020, World Cynipoidea (Hymenoptera): A Key to Higher- Level Groups, Insect Systematics and Diversity 4 (2020), No. 1, pp. 1-69 : 49-50

Synergini

Figs. 227 –232

The traditional composition of this tribe turned out to be polyphyletic, and included any cynipid that was known or presumed to be an inquiline. However, Ronquist et al. (2015) demonstrated that inquilinism has evolved numerous times, and as a result, some members of Synergini s.l. were moved to other tribes (see Ceroptresini , Diastrophini , above). Synergus

is readily identified by the presence of a syntergum on the metasoma, and is by far the most readily collected and speciose genus in the tribe.

Biology. Mainly inquilines of gall-inducing Cynipini on Fagaceae . In some cases, inquilinism reaches a degree where gall inducers do not survive and hatch. It was recently discovered that Synergus itoensis Abe, Ide & Wachi ( Abe et al. 2011) is able to induce galls de novo. Further, this species is found alongside other undescribed species closely allied to S. itoensis from Japan, which lead to Ide et al. (2018) arguing that the Synergini gall inducers have independently arisen from other inquilines.

Rhoophilus is wholly unique being an inquiline forming secondary cells in galls induced by Scyrotis moths ( Cecidosidae ) on Searsia (formerly Rhus ) ( Anacardiaceae ) shrubs and trees. Larval cells expand into the hollow interior of the host gall resulting in death of the gall-inducing moth larva ( van Noort et al. 2007).

Distribution. Mostly Holarctic, but single taxa present in all regions; Rhoophilus endemic to South Africa.

Relevant literature. Ronquist (1999) reviewed the data for and against the monophyly of Synergini s.l.; tribe recently treated in Ronquist et al. (2015). The term agastoparasitism coined in Ronquist (1994) to describe some inquiline biology. Van Noort et al. (2007) thoroughly studied Rhoophilus loewi . Pénzes et al. (2012) reviewed the world oak associated inquilines.

Classification.

Synergini

Agastoroxenia Nieves-Aldrey and Medianero, 2010 ; 1 species NT

Lithosaphonecrus Tang, Melika and Boszó, 2013 ; 9 species OR plus Papua New Guinea

Rhoophilus Mayr, 1881 ; 1 species South Africa

Saphonecrus Dalla Torre and Kieffer, 1910 ; 40 species but taxonomy is uncertain; PA, NA, OR

Synergus Hartig, 1840 ; 137 species but taxonomy is uncertain and far from stable with many more or less dubious taxa; PA, NA, NT

Synophrus Hartig, 1843 ; 7 species wPA

Ufo Melika and Pujade-Villar, 2005 ; 5 species ePA, OR Unplacable Nomina dubia Poncyia Kieffer, 1903 ; 1 species

Figures

Plate 15. Synergini. Fig. 227, Synergus distinctus McCracken & Egbert, 1922, USNMENT01081301. Figs. 228 and 231, Synergus incisus, USNMENT01231859. Figs. 229, 230, and 232, Synergus lignicola Osten-Sacken,1862.USNMENT01448497.