Antistrophus rufus Gillette, 1891

Nastasi, Louis F., Tooker, John F., Davis, Charles K., Smith, Cecil N., Frey, Timothy S., Hatfield, M. J., Presnall, Tara M., Hines, Heather M. & Deans, Andrew R., 2024, Cryptic or underworked? Taxonomic revision of the Antistrophus rufus species complex (Cynipoidea, Aulacideini), Journal of Hymenoptera Research 97, pp. 399-439 : 399-439

Antistrophus rufus Gillette, 1891

Fig. 8

Antistrophus rufus Gillette, 1891: 195. ♀, ♂ (type locality: unknown location in Illinois, USA).

Aulax rufa ( Gillette, 1891) : Kieffer 1902: 93.

Material examined.

Lectotype (deposited at INHS; designated by Frison [1927]). USA • ♀; Illinois; reared from stem of Silphium laciniatum ; record number 5500; INHS Insect Collection 52812.

Lectoallotype (deposited at INHS; designated by Frison [1927]). USA • ♂; same data as lectotype; INHS Insect Collection 52813 .

Paralectotypes. Deposited at AMNH: USA • 1 ♀; same data as lectotype; AMNH _ IZC 00393875 .

Deposited at INHS: USA • 3 ♀ and 1 ♂; same data as lectotype; INHS Insect Collection 294742–294745 .

Deposited at USNM: USA • 4 ♀ and 2 ♂; same data as lectotype; USNMENT 00961146; 01822098 – 01822102 .

Other material

(16 ♀ and 21 ♂). Deposited at INHS: • 5 ♀ and 1 ♂; Illinois, Iroquois County, Buckley Railroad Prairie ; J. Tooker leg.; reared from stem of Silphium laciniatum , emerging in June 2000; INHS Insect Collection 52815–52818; 52820–52821 • 1 ♀ and 1 ♂; Illinois, McLean County, Chenoa, Weston Cemetery Prairie ; J. Tooker leg.; reared from stem of Silphium laciniatum , emerging in June 2000; INHS Insect Collection 18238–18239 .

Deposited at PSUC: USA • 3 ♀ and 4 ♂; Illinois, Champaign County, Gifford, Shortline Railroad Prairie ; 40.305, - 87.999; JF Tooker and AR Deans leg.; galled plant material collected 10 Nov 2020; reared from stem of Silphium laciniatum , emerging in May or June 2021; PSUC _ FEM _ 248301; 248307; 248310; 248315–248317 • 1 ♀ and 1 ♂; Illinois, McLean County, Chenoa, Weston Cemetery Prairie ; 40.725, - 88.606; JF Tooker and AR Deans leg.; galled plant material collected 11 Nov 2020; reared from stem of Silphium laciniatum , emerging in May or June 2021; PSUC _ FEM _ 248293; 248296 • 1 ♀ and 7 ♂; Iowa, Story County, Grant, Interstate 35 and E 13 th St . Prairie Restoration; MJ Hatfield leg.; galled plant material collected 30 Nov 2020; reared from stem of Silphium laciniatum , emerging in May or June 2021; PSUC _ FEM _ 248163; 248308; 248311–248313; 248318–248320 .

Deposited at USNM: USA • 1 ♀ and 2 ♂; Illinois, Ford County, Gifford, Ludlow Railroad Prairie ; J. Tooker leg.; reared from stem of Silphium laciniatum , emerging in June 2000; USNMENT 01822106; 01822109 – 01822110 • 2 ♀ and 1 ♂; Illinois, Iroquois County, Buckley Railroad Prairie ; J. Tooker leg.; reared from stem of Silphium laciniatum , emerging in June 2000; USNMENT 01822104; 01822107 – 01822108 • 7 ♀ and 2 ♂; Illinois, Vermillion County, Fithian Railroad Prairie ; J. Tooker leg.; reared from stem of Silphium laciniatum , emerging in June 2000; INHS Insect Collection 52822–52828; UNSMENT 01822103; 01822105 • 1 ♂; Illinois, Evanston ; reared; UNSMENT 01822112 .

Deposited at WIRC: USA • 1 ♀; Wisconsin, Columbia County, Goose Pd. Bicentennial ; DNR Study SSGB leg.; galled plant material collected Fall 2008; reared from stem of Silphium laciniatum , emerging in July 2009; WIRC 00170506 • 1 ♀; Wisconsin, Dane County, Thousands Rock Pt. Pr. ; 42.99064, - 89.8303; DNR Study SSGB leg.; galled plant material collected 17 Apr 2009; reared from stem of Silphium laciniatum , emerging in May 2009; WIRC 00170687 • 1 ♂; Wisconsin, Waukesha County, Scuppernong Prairie State Natural Area ; 42.89947, - 88.5018; DNR Study SSGB leg.; galled plant material collected 15 Apr 2009; reared from stem of Silphium laciniatum , emerging in Apr 2009; WIRC 00170643 .

Diagnosis.

A. rufus is easily recognized amongst members of the rufus complex by the shape and dimensions of the mesoscutellar foveae (Fig. 8 F ), which are short and subrectangular in A. rufus but longer and subquadrate or ovate in the other species. The narrow, well-defined notauli (Fig. 8 E ) are also characteristic, as the other species all have wider and less-defined notauli. The smallest A. rufus specimens may exhibit slightly wider notauli, but the short, rectangular scutellar foveae are always apparent and readily distinguish this species from others. A. rufus also has the shortest F 2 relative to its width in females (2.8 × as long as wide; Fig. 8 B )).

A. rufus are commonly reared alongside A. minor from inconspicuous, externally imperceptible galls in stems of Silphium laciniatum L.; these species are separated by the characters given above and those in the diagnosis of A. minor .

Description.

Female (Fig. 8 A ) – Body length: 2.3–3.6 mm (x ̄ = 2.9 mm; n = 25; lectotype = 2.8 mm). Color: Antenna color: red brown throughout, at most slightly darker distally than proximally. Head color: vertex and occiput dark red brown, mandibles red brown basally to darker red brown apically, rest of head red brown throughout. Mesosoma color: pronotum and propodeum red brown laterally to dark red brown medially, mesoscutum dark red brown with distinct posterolateral red brown spots, scutellum dark red brown, and mesopleuron dark red brown dorsally and ventrally but red brown medially. Wing membrane color: hyaline throughout. Wing vein color: light brown. Leg color: red brown throughout, except for apical tarsomere which is conspicuously darker. Metasoma color: red brown to dark red brown. Antennae (Fig. 8 B ): Antennomere count: 13. F 1 length: 2.4 × as long as wide. F 2 length: 2.8 × as long as wide. F 2: F 1 length ratio: 1.2. Placodeal sensilla on F 2: absent; sensilla present only on F 3 and following antennomeres. Head (Fig. 8 C ): Upper frons sculpture: reticulate. Gena posterolateral projection in anterior view: distinctly projecting past compound eyes. Facial radiating striae: distinct and complete, reaching compound eyes. Supraclypeal area sculpture: reticulate. Supraclypeal area projection: slightly projecting. OOL vs POL: OOL distinctly longer. OOL vs LOL: OOL greater than twice LOL. POL vs LOL: POL twice LOL. LOL vs DLO: LOL longer. Vertex sculpture: reticulate throughout. Clypeus sculpture: reticulate. Mesosoma (Figs 8 D – F ): Pronotum pilosity: densely pilose along anterior margin and with only sparse setae elsewhere. Pronotum excluding pronotal plate sculpture: reticulate. Pronotal plate sculpture: reticulate. Mesopleuron excluding speculum sculpture: reticulate with fine intermediate striae. Speculum sculpture: reticulate. Mesopleuron pilosity: ventral margin and mesopleural triangle densely pilose and bare elsewhere. Mesoscutum pilosity: sparsely pilose. Mesoscutum sculpture: reticulate. Apparent length of anterior parallel lines: reaching one third across mesoscutum. Morphology of anterior parallel lines: narrow, distinct throughout perceptible length. Apparent length of parapsidal grooves: reaching halfway across mesoscutum. Morphology of parapsidal grooves: narrow, distinct throughout perceptible length. Morphology of median mesoscutal impression: apparent as a shallow impression extending across most of mesoscutum. Notauli completeness: incomplete, distinct posteriorly to indistinct in anterior third. Morphology of notauli: appearing as narrow, well-delimited indentations throughout distinct portions. Metapleural sulcus: meeting posterior mesopleuron at about one third of its height. Lateral propodeal carinae: distinct and subparallel. Metapleuron sculpture: reticulate. Mesoscutellar foveae distinction: distinct, relatively deep anteriorly to shallower and inconspicuously delimited posteriorly. Mesoscutellar foveae sculpture: reticulate. Mesoscutellar disc sculpture: rugose-reticulate, primarily reticulate, but with distinct rugose-reticulate sculpture seemingly restricted to outer margins. Mesoscutellar foveae length: short, occupying only anterior quarter of mesoscutellar disc. Mesoscutellar foveae shape: subrectangular, distinctly wider than long, and separated by a broad, elevated linear carina. Mesoscutellar disc shape: subcircular, about as wide as long. Wings: Marginal cell length: 2.7 × as long as wide. Fore wing distal fringe of marginal setae: absent. Metasoma: Punctation of metasomal terga: T 3 punctate only in posterior third and with T 4 and following punctate throughout.

Male (Fig. 8 G ) – Same as female except for the following: Body length: 1.9–3.5 mm (x ̄ = 2.5 mm; n = 25). Antennae: Antennomere count: 14. F 1 length: 2.1 × as long as wide. F 2 length: 2.5 × as long as wide. F 2: F 1 length ratio: 1.3. Placodeal sensilla on F 2: present. Wings: Fore wing distal fringe of marginal setae: present. Metasoma: Metasoma size: conspicuously smaller than in female.

Biology.

Antistrophus rufus induces inconspicuous, externally imperceptible galls in stems of Silphium laciniatum (Fig. 8 H ) ( 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).

Lastly, two specimens labeled as paralectotypes in the USNM collection (USNMENT 01823001; 01823000) do not appear to be Antistrophus rufus and more closely resemble A. minor . They are both in relatively poor condition; at this time, their species identities cannot be substantiated due to damage to multiple body parts.

Figures

Figure 8. Antistrophus rufus Gillette, 1891 A female lateral habitus (PSUC _ FEM _ 248316) B female proximal antennomeres (PSUC _ FEM _ 246062) C female dorsal head (PSUC _ FEM _ 246062) D female dorsal mesosoma (PSUC _ FEM _ 253129) E female dorsal mesoscutum (PSUC _ FEM _ 253129); not = notaulus F female dorsal scutellum (PSUC _ FEM _ 253129); scf = mesoscutellar fovea G male lateral habitus (PSUC _ FEM _ 248308) H gallss and larvae of A. minor or A. rufus in a stem of Silphium laciniatum L.

Figure 9. Known and potential distributions for species of the Antistrophus rufus complex. Host plant distribution follows Kartesz (2015). States in green reflect established distribution, while states in yellow reflect potential distribution based on records of the host plant.