Antistrophus laurenae

Antistrophus meganae

Antistrophus minor

Antistrophus rufus

Antistrophus jeanae

Biology
Antistrophus laurenae induces inconspicuous, externally imperceptible galls in stems of Silphium integrifolium (Fig. 5H).

Distribution
Material examined in this study reveals that this species occurs in Illinois, Iowa, and Wisconsin (USA; see Suppl. material 1: table 1). A verified iNaturalist record (https://www.inaturalist.org/observations/136446787) also suggests that this species occurs in Mississippi. Known and potential distribution are summarized in Fig. 9.

Biology
Antistrophus meganae induces inconspicuous, externally imperceptible galls in stems of Silphium terebinthinaceum (Fig. 6H) (Tooker et al. 2004; Nastasi and Deans 2021).

Distribution
Tooker et al. (2004) reported this species only from several prairie sites in Illinois (USA). Nastasi and Deans (2021) did not report additional localities; however, the specimens we examined revealed novel records from Wisconsin (Suppl. material 1: table 1). We also sequenced DNA barcodes for individuals from Ohio (Suppl. material 1: table 6), and a series of specimens identified using the key represents a new state record from Michigan (see Discussion; Suppl. material 1: table 1). Known and potential distribution are summarized in Fig. 9.

Biology
Antistrophus minor induces inconspicuous, externally imperceptible galls in stems of Silphium laciniatum (Fig. 7H) (Tooker et al. 2004; Nastasi and Deans 2021). Weld (1926) reported A. minor from Silphium terebinthinaceum, but Weld’s specimens from this host plant truly represent Antistrophus meganae.

Distribution
Antistrophus minor was described from adults reared alongside A. rufus in Illinois. We examined specimens providing new state records from Iowa and Wisconsin. Known and potential distribution are summarized in Fig. 9. It appears that A. minor is likely sympatric with A. rufus throughout the distribution of S. laciniatum, although further rearing of Silphium species will be needed to better understand the role of geography in the distribution of Antistrophus, especially regarding these two species.

[see also entries on gallformers page for Antistrophus rufus]

Biology
Antistrophus rufus induces inconspicuous, externally imperceptible galls in stems of Silphium laciniatum (Fig. 8H) (Tooker et al. 2004; Nastasi and Deans 2021). Records associating A. rufus with other host plants most likely represent distinct species including the other species addressed in the present work.

Distribution
Antistrophus rufus was described from material collected in Illinois (USA) and has since been reported from Kansas (Tooker et al. 2004; Nastasi and Deans 2021). Additional material that we examined revealed additional records from Iowa and Wisconsin, and reiterated occurrence of this species in Kansas (Suppl. material 1: table 1). Known and potential distribution are summarized in Fig. 9.

Remarks
Kieffer (1902) synonymized Antistrophus with Aylax (=Aulax) Hartig, 1840. Some authors (e.g., Beutenmüller 1910) follow Kieffer’s synonymy, but others appear to have rejected or otherwise omitted this change from many works treating the group (e.g., Weld 1951; Nieves-Aldrey 1994). This generic synonymy and the resulting species synonyms were accidentally omitted from Nastasi and Deans’ (2021) catalogue, and we are unable to locate a nomenclatural act reinstating Antistrophus as a valid genus. The genus Aylax has now long been regarded to include only two species of gall wasps inducing galls on Papaver (Papaveraceae) (Nieves-Aldrey 1994; Ronquist et al. 2015). Additionally, the two genera are now placed in different tribes: Aylax is now placed in the tribe Aylacini, while Antistrophus is placed in the Aulacideini. We regard here Antistrophus as a valid genus independent of Aylax, although Antistrophus represents a heterogeneous assemblage as currently defined based on preliminary data from an ongoing revisionary study (Nastasi et al., unpublished data).

Biology
A. jeanae induces inconspicuous, externally imperceptible galls in stems of Silphium perfoliatum (Fig. 4H) (Tooker et al. 2004; Nastasi and Deans 2021).

Distribution
Tooker et al. (2004) reported this species only from several prairie sites in Illinois (USA). Nastasi and Deans (2021) did not report additional localities. However, specimens we examined revealed records from three additional state records: Indiana, Iowa, and Wisconsin. A verifiable iNaturalist observation (https://www.inaturalist.org/observations/114414672) also records this species from Ohio; we have since examined adult gall wasps reared from the plant material from the same site, which confirmed their suspected identity (in litt.). Lastly, a specimen identified during this study (USNMENT 01822302; see complete specimen data in Suppl. material 1: table 1) confirms the occurrence of this species in Missouri (Columbia, Boone County) (see discussion). Known and potential distribution are summarized in Fig. 9.

Cryptic or underworked? Taxonomic revision of the Antistrophus rufus species complex (Cynipoidea, Aulacideini)