Synergus bicolor Ashmead, 1885

Lobato-Vila, Irene & Pujade-Villar, Juli, 2021, The genus Synergus Hartig (Hymenoptera: Cynipidae: Synergini) in the New World: a complete taxonomic revision with a key to species, Zootaxa 4906 (1), pp. 1-121 : 26-28

Synergus bicolor Ashmead, 1885

( Figure 7 )

Synergus bicolor Ashmead, 1885 . Trans. Am. Entomol. Soc. 12: 302. Type material: USNM.

Type material (examined). LECTOTYPE ♂ with the following labels: ‘Jacknsville, Fla.’(white label) / ‘Type’ (orange label, handwritten) / ‘Collection Ashmead’ (white label) / ‘ Synergus bicolor Ashm. ♂’ (white label, handwritten) / ‘USNMENT 00779925’ (white label, QR code) / ‘ Lectotype ♂ Synergus bicolor Ashmead, 1885 , IL-V desig- 2017’ (red label). PARALECTOTYPES (2♂) with the following labels: ‘Jacknsville, Fla.’(white label) / ‘Collection Ashmead’ (white label) / ‘July, C. succinipes’ / ‘ Synergus bicolor Ash. ’ (white label, handwritten) / ‘ Paralectotype ♂ Synergus bicolor Ashmead, 1885 , IL-V desig-2019’ (red label) (1♂); ‘Jacksnville, Fla.’ (white label) / ‘Type’ (orange label, handwritten) / ‘Collection Ashmead’ (white label) / ‘USNMENT 00960112’ (white label, QR code) / ‘ Paralectotype ♂ Synergus bicolor Ashmead, 1885 , IL-V desig-2019’ (red label) (1♂).

Diagnosis. Synergus bicolor belongs to a group of species characterized by having the mesopleuron entirely sculptured, including the speculum, which has no smooth spots; hyaline wings and radial cell of fore wing at most 2.5 times as long as wide; gena broadened behind eye; POL longer than OOL but less than 2.0 times; F1 longer than F2 and female antenna with 13 segments; lateral pronotum with carinae or wrinkles, at least ventrally; pronotum swollen aside seen from above; mesoscutum with transversal carinae, interspaces sculptured; notauli complete and well defined in their entire length, reaching the posterior margin of pronotum; metasoma, at least in females, longer than high in lateral view; and syntergum posteriorly without micropunctures or just with a posterodorsal patch not laterally extended, not dorsodistally incised in females. Synergus bicolor keys out near S. medullae (see below), from which differs by having the transfacial line slightly longer than height of eye ( Fig. 7d ) (equal in S. medullae ); frons finely wrinkled and with sparse, small piliferous punctures, frontal carinae inconspicuous to absent ( Fig. 7d ) and vertex coriaceous, with some small punctures (frons and vertex with broad punctures and frontal carinae very narrow, slightly branched and not reaching lateral ocelli in S. medullae ); margins of pronotum strongly swollen aside and somewhat sharp seen from above ( Fig. 7c ) (slightly swollen but rounded in S. medullae ); and mesopleuron covered with irregular, non-parallel, transversal striae (anteriorly coriaceous, the rest of its surface more or less regularly and parallel, transversely striated, in S. medullae ).

Redescription

FEMALE. Not found (not examined).

MALE. Length. Body length 3.0– 3.5 mm (n = 3).

Color ( Fig. 7 ). Black and yellowish orange. Head yellow, except for a black spot in the ocellar area. Antenna yellow. Mesosoma yellowish orange, mesoscutum with some dark surfaces anteriorly; tegulae yellow. Metasoma chestnut to black. Legs yellow. Wings hyaline, veins yellow.

Head. In frontal view subtrapezoid to rounded, about as wide as high, gena broadened behind eye. Face faintly pubescent, lower face with striae radiating from clypeus. Clypeus indistinct, ventral margin slightly projected over mandibles. Malar space about 0.6 times as long as height of eye. Anterior tentorial pits visible; pleurostomal and epistomal sulcus absent. Transfacial line slightly longer than height of eye. Toruli situated slightly under mid-height of eye; distance between torulus and eye longer than diameter of torulus; distance between toruli clearly shorter than diameter of toruli. Frons ( Fig. 7d ) finely wrinkled and with some small punctures; frontal carinae inconspicuous. Head in dorsal view is almost 2.0 times as wide as long. Vertex ( Fig. 7d ) coriaceous, with some small punctures. POL: OOL: LOL = 16: 10: 9 and diameter of lateral ocelli, 7. Occiput coriaceous, without punctures.

Antenna. 15-segmented according to the original description (tips are broken in all the examined specimens); filiform, not broadened apically; pubescence dense and short. Scape plus pedicel longer than F1; pedicel about 1.3 times as long as wide; F1 almost 2.0 times as long as F2 and strongly curved, kidney-shaped; F2 and F3 subequal; the following segments progressively shorter.

Mesosoma. Just slightly longer than high in lateral view, including nucha, with short and not dense pubescence ( Fig. 7a ). Ratio of length of pronotum medially/laterally: 0.33. Pronotal plate indistinct. Lateral pronotum wrinkled dorsally, carinated basally; lateral margins of pronotum swollen seen from dorsal view, but without lateral carina. Mesoscutum ( Fig. 7c ) about as wide as long, with strong and spaced carinae; anterior parallel lines weakly impressed, reaching 1/3 of the mesoscutum and sometimes interrupted by carinae; notauli complete and well impressed in their whole length, interrupted by carinae; median mesoscutal line absent; parapsidal lines weakly impressed, narrow, reaching tegulae. Mesoscutellum ( Fig. 7c ) rounded, about as long as wide, strongly wrinkled; circumscutellar carina weak but visible, obscured by wrinkles, almost inconspicuous; scutellar foveae almost inconspicuous, obscured by wrinkles. Mesopleuron ( Fig. 7b ) irregularly striated, striae non-parallel and somewhat branched. Metapleural sulcus reaching about 3/4 of mesopleural height. Propodeum pubescent and weakly sculptured; propodeal carinae just slightly convergent posteriorly. Nucha sulcate dorsally and laterally.

Legs. Tarsal claws with a small basal lobe.

Wings. Fore wing pubescent with short marginal setae, about as long as mesosoma plus metasoma. Radial cell closed, about 2.5 times as long as wide; areolet visible, but veins pale. Rs+M inconspicuous, not reaching the basal vein. Basal cell with sparsely spaced setae.

Metasoma. Slightly shorter than head plus mesosoma and about 1.3 times as long as high in lateral view ( Fig. 7a ). First metasomal segment usually with striae reaching only the half of its length, the anterior half smooth. Syntergum smooth, anterolateral pubescence composed of a few setae and posteriorly without micropunctures, or at least with a small and almost inconspicuous posterodorsal patch.

Distribution. USA: Florida ( Ashmead 1885).

Biology. Reared from asexual galls of Andricus quercusfoliatus ( Ashmead, 1881) ( Ashmead 1885) .

Remarks. Synergus bicolor was described from ‘several specimens’ ( Ashmead 1885: 302). We located and examined 3♂ belonging to the type series deposited in USNM. A lectotype has herein been designated.

Since Ashmead mentions the number of segments of female antenna (13), we assume he found females of this species as well. However, we have not found any female belonging to the type series. In his description, Ashmead does not mention the existence of distinctive traits between females and males but the number of antennomeres (13 in females and 15 in males). Then, we consider females and males show no morphological differences except for the sexual ones. According to the original description, metasoma of both females and males is black. In most of the examined specimens, however, it appears brownish or amber probably due to the pass of time.

The host plant is not mentioned in the original description, but Andricus quercusfoliatus is collected from Q. virginiana ( Burks 1979: 1104) .

Figures

FIGURE 7. Synergus bicolor (lectotype, USNMENT 00779925): a) lateral habitus; b) mesopleuron; c) mesosoma in dorsal view; d) head in anterodorsal view.