Necremnus folia, Graham, 1959

Gebiola, Marco, Bernardo, Umberto, Ribes, Antoni & Gibson, Gary A. P., 2015, An integrative study of Necremnus Thomson (Hymenoptera: Eulophidae) associated with invasive pests in Europe and North America: taxonomic and ecological implications, Zoological Journal of the Linnean Society 173 (2), pp. 352-423 : 392-396

NECREMNUS FOLIA (WALKER) ( FIGS 78–84 )

Eulophus folia Walker, 1839: 147 . ♂ lectotype (BMNH, here designated).

Eulophus diyllus Walker, 1939: 185 : ♀ (BMNH, lost); synonymy by Boucˇek & Askew (1968: 65). Necremnus folia Graham, 1959: 184 .

Type material

There is no indication in the original description of whether the type series of E. folia , collected in Ireland, consisted of more than a single individual. The BMNH has a single, card-mounted male ( Fig. 78 ) with the following four labels: (1) a circular, purple-bordered label with ‘LECTOTYPE’; (2) a rectangular label with ‘ Folia ’ handwritten on one side and ‘Quarts’ on one line and ‘per Dozen.’ on another line printed on the other side; (3) a rectangular label with ‘ Eulophus Folia Walker LECTOTYPE: ♂ M. de V. Graham det. 1958’ partly printed and handwritten; and (4) a square label with ‘B.M. TYPE HYM. 5.2511’. As Graham did not validly designate a lectotype through publication under ICZN rules, in order to stabilize the concept of the name we designate this male as the lectotype of E. folia . The lectotype is entire.

In addition to the lectotype, the BMNH has a pointmounted male with the following five labels: (1) a circular label with ‘38/7.12/68’ on three separate lines; (2) a rectangular label with ‘Clermont’ handwritten; (3) a rectangular label with ‘ Eulophus Tyrrhenus Walker’ written on one side and ‘Stood under this name in old B.M. Coll. C. Waterhouse.’ printed on the other side; (4) a rectangular label with ‘ ♂ in genus Comedo Ch. Ferriere det.’ partly handwritten and partly printed; and (5) a rectangular label with ‘ Necremnus ’ handwritten. This male is from France ( Walker, 1846a), is a Necremnus , and is very similar to the lectotype of N. folia , including lacking mps from all three rami and having the propodeal spiracle separated slightly from the metanotum. The dorsal mesosomal sculpture is stronger than for the lectotype, but this is to be expected because it is a larger individual. The scutellum has similar elongate, imbricate to very shallowly reticulate-imbricate sculpture.

Description

Male (lectotype)

Body ( Fig. 78 ) about 1.2 mm in length. Head dark brown with very slight violaceous lustre under some angles of light. Antenna ( Fig. 79 ) with scape about 3.4 × as long as wide; length of funiculars and clava about 1.2, 1.4, 1.5, 1.8, and 2.3 × length of pedicel, with F4 about 2.25 × and clava about 2.5 × as long as wide; rami with long, hair-like setae, elongate-slender with R1 about 2.2 × length of scape, and all rami without mps. Mesosoma dark brown with very slight violaceous lustre under some angles of light ( Figs 78, 80 ); tegula uniformly brown. Mesonotum ( Fig. 80 ) with mesoscutum mesh-like reticulate; scutellum longitudinally, shallowly reticulate- imbricate to imbricate. Fore wing hyaline ( Figs 78, 81 ); basal cell apically and speculum posteriorly delineat- ed by complete rows of setae, and mediocubital fold basal to basal fold setose for about two-thirds of length, with four setae basal to seta marking juncture of basal and mediocubital folds ( Fig. 82 ); speculum broadly bare dorsally; approximate ratio of cc: mv: stv: pmv = 45:34:13:16. Legs dark except with protibia longitudinally, knees and at least basal tarsomeres pale, the tarsi increasingly more distinctly brown apically. Metanotum finely mesh-like coriaceous. Propodeum ( Fig. 80 ) without distinct median carina, mesh-like coriaceous-alutaceous to very shallowly reticulate; spiracle slightly separated from posterior margin of metanotum.

Female

Body ( Fig. 83 ) about 1.5–1.7 mm in length. Head dark brown with variably distinct and extensive green to blue or limited coppery lustres under some angles of light. Antenna dark brown, the scape with only very slight metallic lustre; length of flagellum + pedicel subequal to about 0.9–1.0 × width of head; flagellum with length of F1 + anelli about 1.3–1.8 × as long as wide and 1.0–1.25 × length of pedicel, F2 and F3 both about 1.3–1.8 × as long as wide, and clava about 2.5– 2.6 × as long as wide. Mesosoma ( Fig. 83 ) dark with variably distinct green to coppery or violaceouscoppery lustres; tegula uniformly dark brown. Mesonotum with mesoscutum mesh-like reticulate; scutellum reticulate-imbricate with reticulations usually comparatively elongate-narrow ( Fig. 84 ). Fore wing hyaline or at most very faintly and inconspicuously infuscate between stigmal vein and base of marginal vein; basal cell apically and speculum posteriorly delineated by complete rows of setae, and mediocubital fold setose over at most apical half of basal cell; speculum broadly bare dorsally; postmarginal vein subequal in length to stigmal vein. Legs dark except protibia at most dorsolongitudinally pale within basal half, and knees and basal tarsomeres pale. Metanotum finely mesh-like coriaceous. Propodeum ( Fig. 84 ) with almost complete median carina, mesh-like coriaceous-alutaceous to sometimes more distinctly reticulate mesally; spiracle slightly separated from posterior margin of metanotum.

Distribution

Europe (see Noyes, 2013).

Hosts

Ceutorhynchus sp. ( Gomez & Zamora, 1994) on Hormathophylla spinosa (L.) ( Brassicaceae ). This record requires confirmation of the parasitoid identification

because the parasitoids of Curculionidae on Brassicaceae usually belong to the N. tidius group.

Discussion

We remove N. rhaecus from synonymy under N. folia for the reasons discussed under the former name. Females that we identify as N. folia more closely resemble the lectotype of N. folia than does the lectotype of N. rhaecus and also more closely fit the concepts given in the keys by Boucˇek (1959) and Graham (1959). They differentiated females of N. folia from those of N. cosconius by the former having the fore wings hyaline or faintly, uniformly infuscate. Females of N. cosconius were said to nearly always have two infuscations that sometimes are joined or rarely absent. However, the couplet acknowledges the variability of fore wing infuscation and the possibility that some N. cosconius entirely lack infuscation. Some N. cosconius -group females that we have seen with entirely hyaline fore wings have a more elongate-slender, reticulate-imbricate scutellum similar to the lectotype of N. folia ( Fig. 80 ), whereas others have a more uniformly mesh-like reticulate-imbricate scutellum similar to that of N. cosconius ( Fig. 62 ). Females with the former scutellar sculpture are somewhat smaller than typical N. cosconius females, as are some with the latter scutellar sculpture and, unlike typical N. cosconius females, all have the protibia longitudinally pale only within about its basal half. Molecular analyses would provide valuable independent information to determine more confidently the morphological limits of the two species and the reliability of different features for species differentiation.

NECREMNUS RHAECUS ( WALKER) REVISED STATUS

( FIGS 85–91 )

Eulophus rhaecus Walker, 1939: 182–183 . ♀ lectotype ( BMNH, here designated); synonymy under Necremnus folia by Boucˇek & Askew (1968: 65).

Type material

There is no indication in the original description of whether the type series of E. rhaecus , collected near London, consisted of more than a single individual. The BMNH has a single, card-mounted female ( Fig. 85 ) with the following five labels: (1) a circular, purplebordered label with ‘LECTOTYPE’; (2) a rectangular label with ‘ Eulophus Rhaecus Walker’ written on one side and ‘Stood under this name in old B.M. Coll. C. Waterhouse.’ printed on the other side; (3) a rectangular label with ‘in genus Necremnus Ch. Ferriere det.’ (determination line printed); (4) a rectangular label with ‘ Eulophus Rhaecus Walker LECTOTYPE: ♀ M. de V. Graham det. 1958’ partly printed and handwritten on it; and (5) a square label with ‘B.M. TYPE HYM. 5.2510’. As Graham did not validly designate a lectotype through publication under ICZN rules, in order to stabilize the concept of the name we designate this female as the lectotype of Eulophus rhaecus . The lectotype is entire.

Description

Female (lectotype)

Body ( Fig. 85 ) about 1.4 mm in length. Head dark brown. Antenna ( Fig. 86 ) with scape similarly dark as flagellum; length of flagellum + pedicel about 1.1 × width of head; flagellum with length of F1 + anelli about 1.75 × as long as wide and about 1.2 × dorsal length of pedicel; F2 about 1.5 ×, F3 about 1.7 ×, and clava about 3 × as long as wide. Mesosoma brown with variably distinct green lustre under different angles of light ( Figs 85, 89 ); tegula uniformly brownish yellow. Mesonotum ( Fig. 87 ) with mesoscutum mesh-like reticulate; scutellum mostly mesh-like coriaceous, at most only very obscurely imbricate or reticulate-imbricate laterally under some angles of light. Fore wing ( Figs 85, 88 ) hyaline; basal cell apically and speculum posteriorly delimit- ed by complete rows of setae, and mediocubital fold with only two setae basal to seta marking juncture of basal and mediocubital folds ( Fig. 89 ); speculum broadly bare dorsally ( Fig. 89 ); approximate ratio of cc: mv: stv: pmv = 50:42:17:[?]. Legs ( Fig. 85 ) dark except with protibia dorsolongitudinally, knees and basal tarsomeres pale. Metanotum with dorsellum very finely mesh-like coriaceous ( Fig. 87 ). Propodeum ( Fig. 87 ) with complete median carina, otherwise mesh-like coriaceousalutaceous; spiracle with anterior margin slightly overlapped by posterior margin of metanotum. Gaster ( Fig. 85 ) brown; about as 1.75 × long as wide and about 1.1 × length of mesosoma; syntergum short.

Male

Unknown.

Distribution

England, Sweden.

Hosts

Unknown.

Discussion

Eulophus rhaecus was synonymized under N. folia by Boucˇek & Askew (1968) based on the opinion of Marcus Graham, but without giving reasons for the sex association resulting in the synonymy. Furthermore, when Graham (1991) designated a lectotype from OXUM to stabilize the generic placement of Eulophus thespius Walker , he stated that the only Walker specimen labelled as E. thespius in the BMNH disagrees markedly with the original description and is a female of N. folia . This is true in the sense that it has a similar scutellar sculptural pattern and the anterior margin of the propodeal spiracle slightly overlapped by the metanotum ( Fig. 90 ), as well as the mediocubital fold mostly bare. The postmarginal vein is only slightly longer than the stigmal vein. The female is larger (about 2 mm) than the lectotype of E. rhaecus . Probably correlated with this is the scutellar sculpture being more distinct with more obvious, longitudinally reticulateimbricate sculpture laterally, but mesally still quite broadly mesh-like coriaceous with distinctly impressed lines ( Fig. 90 ). The propodeum is also quite distinctly reticulate mesally, possibly also correlated with its larger size. We have also seen a single female from Sweden (BMNH) that is morphologically similar to the latter female ( Fig. 91 ). By contrast, the lectotype male of N. folia has the propodeal spiracles slightly separated from the metanotum ( Fig. 80 ), a more longitudinally reticulate-imbricate scutellum ( Fig. 80 ), and a more extensively setose mediocubital fold ( Fig. 82 ). Because of these differences and because we observed females that appear to fit Boucˇek’s (1959) and Graham’s (1959) key concept of N. folia (see under N. folia ), we believe that the synonymy of N. rhaecus under N. folia is incorrect. We therefore re-establish this name as a valid species. Molecular analyses or association of the sexes through rearing would provide additional evidence of species status.

Females of N. rhaecus could be keyed to N. hippia if the length of the postmarginal vein is not apparent because of their slightly overlapped propodeal spiracles and uniformly coloured tegulae, but even the smallest N. hippia females have the scutellum reticulateimbricate to slightly scalloped in appearance. Males of N. rhaecus presumably have a similar scutellar sculpture pattern as females and would probably also key to N. hippia , assuming the presence of mps on the second and third rami.

Figures

Figures 78–84. Necremnus folia. 78–82, ♂ lectotype: 78, dorsal habitus; 79, left antenna; 80, dorsal mesosoma; 81, fore wing; 82, fore wing base. 83, ♀ dorsal habitus (2013-76). 84, scutellum-propodeum (2013-76).

Figures 57–64. Necremnus cosconius. 57–60, Eulophus amempsimus, lectotype ♀: 57, dorsal habitus; 58, antenna; 59, left fore wing; 60, dorsal mesosoma. 61; ♀ dorsal mesosoma (2013-44). 62–64, E. amempsimus, lectotype ♀: 62, scutellum and dorsellum; 63, stigmal and postmarginal veins; 64, base of fore wing.

Figures 85–91. Necremnus rhaecus. 85–89, ♀ lectotype: 85, dorsal habitus; 86, antennae; 87, dorsal mesosoma; 88; fore wing; 89, fore wing base. 90, ♀ scutellum and metanotum (2013-75); 91, ♀ scutellum-propodeum (2013-77).