Hymenoptera
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publication ID |
https://doi.org/ 10.6620/ZS.2022.61-57 |
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persistent identifier |
https://treatment.plazi.org/id/1E1F87DD-FF92-FFD4-9A9D-2ADA9FA3FEE8 |
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treatment provided by |
Felipe |
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scientific name |
Hymenoptera |
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( Hymenoptera : Cynipoidea : Figitidae : Euceroptrinae )
803 individuals (mean = 133.8, range 5–727) reared from six gall types ( Table S1).
Summary of Natural History: The biology of Euceroptres is not well studied and it is not known whether members of this genus function as inquilines, parasitoids, or hyperparasitoids. Only four species of Euceroptres are previously described from galls of five species of gall wasps ( Buffington and Liljeblad 2008). All known hosts are oak galls. The apparently small number of species and hosts for Euceroptres , coupled with the possibility that each species may have a limited range of hosts has led to the speculation that these are the surviving members of a previously more species-rich genus ( Buffington and Liljeblad 2008).
Relationship to galler phylogeny: Unlike the two genera of cynipoid associates of oak galls treated above, there are no published records of Euceroptres from the Palearctic ( Buffington and Liljeblad 2008), though one unpublished record from Serbia is mentioned in Buffington et al. (2020). Most Nearctic gallers in our collections were not found to have associations with Euceroptres , though the nine that mapped onto the galler phylogeny were widely scattered across the tree ( Fig. 3a View Fig ).
Biogeography and oak tree section: All six species reared in this effort were from galls collected in the Eastern North American floristic region ( Fig. 3b View Fig ). However, two species ( Euceroptres maritimus Weld on Callirhytis quercussuttoni (Bassett) and Euceroptres montanus Weld on Disholandricus truckeensis (Ashmead)) were previously reared from California and Oregon. Three of the six gall hosts in our collections were collected from trees in oak section Quercus , while the remaining three were from trees in section Lobatae ( Fig. 3c View Fig ). Previous collections were from galls found on oaks in sections Quercus and Lobatae as well as Protobalanus ( Buffington and Liljeblad 2008; Manos and Hipp 2021). If Euceroptres are host specific as has been previously suggested ( Buffington and Liljeblad 2008), our failure to rear them from western collections may well be a function of our collections not having included specific hosts.
Tree organ and gall size: All Euceroptres reared in this study were from galls on leaves or on petioles ( Fig. 3d View Fig ). The host gall farthest from the leaf proper was Callirhytis scitula Bassett , a woody gall that occurs at the intersection between the petiole and stem. The two Euceroptres species known from the Pacific coast, however, are both associated with stem galls ( Buffington and Liljeblad 2008). All six hosts among our collections were classified as either medium or large, with no rearings from any galls smaller than 5 mm ( Fig. 3e View Fig ).
Co-occurrence with other natural enemies: Euceroptres were significantly more likely to co-occur with Ceroptres (P = 0.008) and with the parasitoid genus Euderus (P = 0.015) ( Fig. 3f View Fig ). All six gall types from which we reared Euceroptres also had Ceroptres emerge and only one gall type from which we reared Euceroptres failed to yield Euderus ( Andricus foliaformis Gillette ). In contrast, Euceroptres were significantly negatively correlated with Synergus inquilines (P = 0.005) and in fact the two genera were never reared from the same gall types.
Additional Notes: The small number of rearing records for Euceroptres , both in the present study and historically, precludes definitive statements about this genus and its association with oak gall types. On the other hand, we now have initial information about which gall types do, and more importantly, apparently do not host Euceroptres . All six gall hosts identified here, and the few additional previously published host records ( Buffington and Liljeblad 2008), are multichambered, integral galls (i.e., non-detachable) and larger than 0.5 cm, suggesting that one or more of these characters may be important with respect to host range for Euceroptres . However, many other galls with these same characters do not appear to be Euceroptres hosts, so while these characters may be necessary, it is not clear that they are sufficient for Euceroptres attack and development. It may be that Euceroptres requires the presence of another gall associate either because it is a parasite of wasps in one of these genera or because it is an inquiline or gall inducer that first requires, e.g., Ceroptres to make a gall within the gall (which would make Euceroptres a galler of galls-within-galls).
Though we generally did not key our collections to species, the small number of collections and the availability of the key to the four species produced by Buffington and Liljeblad (2008) allowed us to make an exception for Euceroptres . Not surprisingly, given the growing recognition of cryptic diversity and higher than previously-recognised host specificity among parasitic wasps ( Forbes et al. 2009; Smith et al. 2011; Condon et al. 2014; Hood et al. 2015; Sheikh et al. 2022), none of the wasps we reared matched the descriptions of any of the four named Nearctic species. All samples had 10 flagellomeres and well developed micropores on their abdominal tergites, combinations not found in Buffington and Liljeblad (2008). None of the cynipid hosts producing the gall types from which we reared Euceroptres overlapped with previous rearing records, save for Euceroptres whartoni Buffington & Liljeblad in a) b)
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e) f)
galls of Andricus quercuspetiolicola (Bassett) . However, Buffington and Liljeblad (2008) list this host record as dubious. Our collections to date may therefore include one or more undescribed species.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.