Discovery of a New Gall-Inducing Species in the Inquiline Tribe Synergini (Hymenoptera: Cynipidae): Inconsistent Implications from Biology and Morphology

Abstract

A new gall-inducing species of the inquiline tribe Synergini (Hymenoptera: Cynipidae), Synergus itoensis Abe, Ide & Wachi, sp. nov., from Japan is described. The morphological features of the adult clearly indicate that this new species is assigned to the genus Synergus Hartig, 1840, and members of Synergini have all been known as inquilines to date. Field observation showed that adult emergence of this gall wasp from acorns of the evergreen oak, Quercus (Cyclobalanopsis) glauca Thunberg, on the ground is well synchronized with the rapid growth period of fresh acorns in late summer. A rearing experiment demonstrated gall induction by S. itoensis in the seed coat of the acorn of Q. (C.) glauca under field conditions. Moreover, the occurrence of arrhenotoky in this gall wasp and lack of a significant effect of gall induction on acorn size were indicated. Judging from the inconsistency of biological and morphological features in S. itoensis, gall-inducing ability might have been regained within Synergini. The advantages and disadvantages of gall induction in acorns are discussed.

A New Species of Saphonecrus (Hymenoptera, Cynipoidea) Associated with Plant Galls on Castanopsis (Fagaceae) in China

“…All synergine genera are known to be relatively conservative in host use, both with regard to the host gall maker and the associated host plant (Ronquist and Liljeblad 2001). Periclistus Hartig use galls induced by the genus Diplolepis on rose plants (Ritchie 1984), Synophromorpha Ashmead species use Diastrophus galls on plants of Rubus in the rose family (Ritchie andShorthouse 1987, Abe 1998), and Rhoophilus Mayr use galls induced by a cecidosid moth genus Scyrotis on Rhus species (Anacardiaceae) (Van Noort et al 2007), whereas the rest all exploit galls on oaks, mostly induced by wasps of the tribe Cynipini Liljeblad 2001, Melika et al 2005, NievesÐAldrey and Medianero 2010, but also see Abe et al 2011. Most of the oak associated inquiline genera fall into the so-called Synergus complex (Ronquist and Liljeblad 2001), which was subsequently shown to be monophyletic (Nylander et al 2004).…”

Eastern Palearctic oak cynipid inquilines (Hymenoptera: Cynipidae: Synergini) and associated gallwasps (Hymenoptera: Cynipidae: Cynipini)

“…One Synergus species, S. itoensis Abe, Ide & Wachi, appeared to induce its own gall in the seed coat of the acorn of Quercus (subgen. Cyclobalanopsis) glauca, a unique behaviour for inquilines when the species have not lost the capability to induce its own gall (Abe et al 2011). Synergus castaneus Pujade-Villar, Bernardo & Viggiani, described from China, is the first known cynipid inquiline (Synergini) that emerge from Castanea galls (Fagaceae) (but not from the well-known gall of…”

“…This species is associated with galls developing on Castanopsis carlesii which from Liu et al (2012) never reared any gallwasp, thus they do not exclude the possibility that S. hupingshanensis might be a gall inducer . Such is the case with Synergus itoensis Abe, Ide & Wachi (Abe et al 2011). Melika & Schwéger, 2015 This species was reared from asexual leaf galls of Ussuraspis sp.…”

“…This species shows some morphological similarity to S. belizinellus and S. ishikarii. (Wachi, Ide & Abe, 2011) This species known from Japan (Honshu and Kyushu) was reared from a gall midge Ametrodiplosis acutissima (Monzen) (Diptera: Cecidomyiidae) galls on Q. acutissima (Quercus section Cerris) (Wachi et al 2011b). The species has a strong, complete lateral frontal carina, and thus, it is not a Saphonecrus and was transferred by us to Synergus.…”

“…Before our work 12 valid species of Synergus were known from the Eastern Palearctic (Sadeghi et al 2006, Bernardo et al 2013, Abe et al 2011, Pujade-Villar et al 2014a.…”