Necremnus tidius, (WALKER)

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 : 411-417

publication ID	https://doi.org/ 10.1111/zoj.12210
persistent identifier	https://treatment.plazi.org/id/293AD62E-FFAB-3463-1309-FE82FC3AFDDE
treatment provided by	Felipe
scientific name	Necremnus tidius
status

Treatment

NECREMNUS TIDIUS (WALKER) View in CoL ( FIGS 151–175 View Figures 151–156 View Figures 157–164 View Figures 165–171 View Figures 172–175 )

Eulophus Tidius Walker, 1839: 146–147 View in CoL . ♂ lectotype (BMNH, here designated).

? Eulophus Zeugma Walker, 1839: 183 View in CoL . ♂ syntypes (BMNH, lost); synonymy under N. tidius View in CoL by Graham in Boucˇek & Askew (1968: 67).

Eulophus Metanira Walker, 1839: 183–184 View in CoL . ♀ lectotype (OXUM, examined) designated by Graham (1991: 8); synonymy under N. tidius View in CoL by Graham (1991: 8).

Eulophus Mamurius Walker, 1848: 232 View in CoL . ♂ lectotype (BMNH, here designated); synonymy under N. tidius View in CoL by Graham in Boucˇek & Askew (1968: 67).

Necremnus tidius View in CoL ; Graham, 1959: 184.

Type material

Walker (1839) described E. tidius from at least two males, describing also a ‘ Var. β’ from material collect- ed near London. A single card-mounted male ( Fig. 151 View Figures 151–156 ) remains in the BMNH with the following six labels: (1) a circular, purple-bordered label with ‘LECTOTYPE’; (2) a rectangular, handwritten label with ‘ Tidius ’; (3) a ‘Ch. Ferriere det.’ label with ‘ ♂ prob. in Necremnus ? handwritten; (4) a rectangular label with “ Eulophus Tidius Walker , LECTOTYPE: ♂, M. de V. Graham det. 1958’ partly printed and handwritten; (5) a square label with ‘B.M. TYPE HYM. 5.2508’; and (6) a rectangular, handwritten label with ‘right antenna on slide’. The lectotype is entire except for the right antenna, which was dissected and slide mounted ( Fig. 156 View Figures 151–156 ) by J. Noyes. The slide has two labels with ‘ ♂ Eulophus tidius Walker LECTOTYPE right antenna LT 5.2508’ and ‘ 25Jan2012 ’. We did not observe any mps on the rami of the slide-mounted antenna, but cannot be certain of absence because of the condition of the antenna. The left antenna has at least a single mps on the outer surface of the third ramus ( Fig. 155 View Figures 151–156 ). The tegulae appear mostly brown ( Fig. 153 View Figures 151–156 ), but are linearly yellowish along the inner margin basally. 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. anaxippus . There is no indication in the original publication that Walker (1839) described E. metanira from more than one female, but Graham (1991) selected the single remaining female in OXUM as the lectotype. It is card mounted and entire ( Fig. 157 View Figures 157–164 ). Synonymy under N. tidius is indicated by the fore wing being comparatively extensively setose without a distinct speculum ( Fig. 160 View Figures 157–164 ) and the propodeal spiracle being well separated from the metanotum ( Fig. 159 View Figures 157–164 ). The tegulae are uniformly dark brown.

There is no indication in the original publication that Walker (1839) described E. mamurius from more than one male. A single BMNH male ( Fig. 161 View Figures 157–164 ) bears the following four labels: (1) a circular, purple-bordered label with ‘LECTOTYPE’; (2) a rectangular, handwritten label with ‘ Mamurius ’; (3) a rectangular label with ‘ Eulophus Mamurius Walker , LECTOTYPE: ♂, M. de V. Graham det. 1958’ partly printed and handwritten; and (4) a square label with ‘B.M. TYPE HYM. 5.2513’. 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. mamurius . Synonymy under N. tidius is indicat- ed by the propodeal spiracles being separated from the metanotum ( Fig. 164 View Figures 157–164 ) and the fore wing being comparatively extensively setose with only a narrow speculum ( Fig. 163 View Figures 157–164 ). Although the antennae are covered in glue on the card at least the third ramus appears to have at least one mps ( Fig. 162 View Figures 157–164 ). The tegulae are uniformly dark brown.

Walker (1839) described E. zeugma from at least two males, from near London and North Wales. Neither male could be found in the BMNH and both syntypes are presumed lost. The original description is insufficient to confidently establish synonymy of N. zeugma under N. tidius or N. hippia , but we tentatively retain the prior synonymy of Graham in Boucˇek & Askew (1968) for the sake of stability.

Description

Female

Body 1.3–2.1 mm in length. Head usually variably dark or green to bluish-green except usually for at least slight coppery to bronze lustres under some angles of light (smaller individuals often with less distinct metallic lustre). Antenna ( Fig. 167 View Figures 165–171 ) with scape similarly dark as flagellum; length of flagellum + pedicel about 1.1– 1.2 × width of head; flagellum with length of first funicular + anelli about 2.1–2.8 × as long as wide and about 1.25–1.6 × length of pedicel; second and third funicular often quite distinctly oblong, but second about 1.7–2.0 × and third about 1.6–2.0 × as long as wide, and clava about 2.8–3.5 × as long as broad. Mesosoma rarely mostly dark brown with violaceous-coppery lustres, but usually green ( Figs 165 View Figures 165–171 , 172 View Figures 172–175 ) to somewhat bluish-green except often for variably distinct and extensive coppery or reddish-coppery lustres ( Fig. 173 View Figures 172–175 ) under some angles of light; tegula uniformly brown or variably distinctly and extensively yellowish along inner margin or basally, but brown apically or apicolaterally. Mesonotum with mesoscutum reticulate; scutellum longitudinally reticulate-imbricate on either side of midline. Fore wing hyaline; speculum comparatively narrowly bare dorsally ( Fig. 168 View Figures 165–171 ); basal cell apically and speculum posteriorly delineated by complete rows of setae, and mediocubital fold with two to seven setae basal to basal fold often over at least apical half of basal cell; subcubital line of setae with two or more rows of setae along most of its length ( Fig. 168 View Figures 165–171 ); basal cell sometimes with one dorsal setae but in ventral view usually with at most line of spots or minute spicules adjacent to submarginal vein; postmarginal vein 1.6– 1.75 × length of stigmal vein. Legs ( Fig. 166 View Figures 165–171 ) dark except protibia dorsolongitudinally, knees narrowly, and basal tarsomeres of meso- and metatarsi pale, although rarely second tarsomeres brownish to white. Metanotum with dorsellum coriaceous, alutaceous or more distinctly mesh-like reticulate. Propodeum with median carina over most of length; often somewhat more finely sculptured, alutaceous to mesh-like coriaceous than dorsellum; spiracle obliquely oval, usually at least very slightly separated from metanotum ( Fig. 172 View Figures 172–175 ) although sometimes uniformly developed rim touching metanotum ( Fig. 173 View Figures 172–175 ). Gaster ( Fig. 165 View Figures 165–171 ) mostly brown in smaller individuals to variably extensively green to blue or purple dorsally, although posterior margins of basal four tergites at least broadly brownish along posteri- or margins and sometimes up to basal five tergites entirely brown to coppery-brown; about 1.6–2.4 × as long as wide (smaller ratio typical of critical point-dried, inflated specimens, and larger ratio of air-dried specimens with gaster strongly collapsed), and subequal in length to combined length of head + mesosoma; syntergum short.

Male ( Figs 151 View Figures 151–156 , 161 View Figures 157–164 )

Similar to female except for antennal structure and as follows: body sometimes much more distinctly blue to purple ( Figs 151 View Figures 151–156 , 175 View Figures 172–175 ); speculum sometimes not as distinctively narrow; propodeal spiracle more commonly obviously separated from metanotum ( Figs 174, 175 View Figures 172–175 ). Antenna with flagellar rami long and slender, with long, hair-like seta, but with at most comparatively sparse and inconspicuous mps, rarely without but usually with at least one mps basally on R3 of at least one antenna, often with one or two mps on one or both of R2 and R3, and rarely with up to three mps on R3 of one antennae, the two antennae usually being asymmetric in mps pattern ( Figs 155 View Figures 151–156 , 162 View Figures 157–164 , 169, 170 View Figures 165–171 ); scape with row of closely spaced sensory pores along ventral margin mesally, the distance between basal-most pore and basal margin similar to or only slightly greater than distance between apical-most pore and apical margin, and much less than length of row of pores ( Fig. 171 View Figures 165–171 ).

Distribution

North America (British Columbia, Ontario) and Europe ( England, France, Romania, Sweden).

Hosts

Ceutorhynchus cardariae on Car. draba ; Ceutorhynchus erysimi (Fabricius) and Ce. typhae on Cap. bursapastoris. Other hosts listed ( Noyes, 2013) require confirmation of the parasitoid identification, especially those from Lepidoptera , as the species in the N. tidius group are associated with Coleoptera . A further confirmed plant host record based on a specimen in R. R. Askew’s collection ( England, Yorkshire, 23.vii.1963) is Cakile maritima Scop. (Brassicaceae) .

Discussion

Recognition of N. tidius in North America is discussed under N. duplicatus and in Europe under N. leucarthros . Variation in position of the propodeal spiracles relative to the metanotum (see Discussion under N. duplicatus ) makes keying N. tidius females more difficult, but a comparatively narrow speculum in combination with a more extensively setose subcubital setal line ( Fig. 168 View Figures 165–171 ) and often more distinctively oblong funiculars ( Fig. 167 View Figures 165–171 ) will help identify those females in which the spiracles appear to touch the metanotum ( Fig. 173 View Figures 172–175 ). Males are also variable in the number and arrangement of mps on R2 and R3, rarely being entirely absent but usually with at least one mps and rarely up to three mps on R3 of one antenna ( Figs 169, 170 View Figures 165–171 ). This mps pattern is intermediate between that of N. duplicatus and N. aenigmaticus , which typically lack mps, and N. hippia , which normally has a greater number and therefore more conspicuous mps. As discussed under N. duplicatus , males of N. duplicatus very rarely have a single mps on R3 of one antenna ( Fig. 113 View Figures 111–116 ) whereas rare N. tidius males apparently lack mps from all rami. The absence of mps can be difficult to establish confidently because the presence of just a single mps on one ramus can be very difficult to observe even in well-preserved males. However, males that we identify as N. tidius without any mps have the propodeal spiracles obviously separated from the metanotum ( Figs 174, 175 View Figures 172–175 ). Furthermore, amongst N. tidius complex species ( N. duplicatus , N. aenigmaticus , N. hippia , and N. tidius ), males of N. tidius uniquely have the sensory pores of the scape occupying a mesal position ( Fig. 171 View Figures 165–171 ) rather than within the apical half of the scape ( Figs 102 View Figures 98–102 , 138 View Figures 133–138 ).

Within the N. tidius group, the colour pattern of the tegulae appears to be uniquely variable in N. tidius . Some individuals appear to have an entirely dark tegula, whereas in others it is only very narrowly yellow along the inner margin to obviously yellow except apically or apicolaterally similar to N. aenigmaticus and N. metalarus . Individuals of N. tidius that we sequenced included females with the tegulae entirely or virtually entirely dark (e.g. NT31, NT33) and ones with the tegulae quite obviously partly pale (e.g. NT20, NT33, NBT95). Careful observation is required and a bicoloured pattern may not be apparent in some instances in which the wings are held over the body and the tegula is aligned longitudinally with its inner, lighter coloured margin slightly overlapped by the mesoscutal margin. All the individuals that we identify as N. aenigmaticus have a partly to entirely yellowish tegula ( Figs 94, 95 View Figures 92–97 ), whereas individuals of the other N. tidius group species have an entirely dark tegula. Individuals of N. metalarus within the N. artynes group also have a bicoloured tegula ( Fig. 28 View Figures 26–31 ), but amongst other features females are readily distinguished by their more strongly sculptured, reticulate propodeum ( Fig. 37 View Figures 32–39 ), and a broad speculum ( Fig. 36 View Figures 32–39 ), and males by having mps on the basal ramus.

The BMNH has a single female of N. tidius from England labelled as ‘ex. Helianthemum leaf miner’ ( Cistaceae ) and a male and female from an unstated locality, although probably England, labelled as reared from clover heads. The clover host might have been the clover head weevil, Hypera meles (Fab.) (Curculionidae) , but regardless, the clover and Helianthemum hosts probably were not Ceutorhynchus species. We did not sequence material of N. tidius from England, the type locality of N. tidius , and this should be carried out, particularly from specimens reared from such plants as clover, to determine whether their genotypes are the same as what we here identify as N. tidius or belong to yet another cryptic species.