Idiomacromerus asphodeli Ribes, 2019

Delvare, G., Escolà, A. Ribes, Stojanova, A. M., Benoit, L., Lecomte, J. & Askew, R. R., 2019, Exploring insect biodiversity: the parasitic Hymenoptera, chiefly Chalcidoidea, associated with seeds of asphodels (Xanthorrhoeaceae), with the description of nine new species belonging to Eurytomidae and Torymidae, Zootaxa 4597 (1), pp. 1-90 : 66-68

Idiomacromerus asphodeli Ribes sp. n.

( Figs 29 A–F)

Type material. Holotype ♀: SPAIN: Castellón, Vinarós , 40.49368°N 0.20821°E, ex fruit of A. fistulosus , collected 7.vi.2012, emerged 22.vi.2012 (A. Ribes) (in MNCN) . Allotype ♂: same data as holotype (in MNCN) . Paratypes (40 ♀ 40 ♂): same data as holotype except emergence dates 21–22.vi.2012 (6 ♀ in BMNH, 7 ♀ in NMS, 2 ♀ 2 ♂ to GDPC for photography, the rest in MNCN and RAPC) .

Other material. SPAIN: Castellón, Vinarós , 40.49368°N 0.20821°E, ex fruits of A. fistulosus , collected on 7.vi.2012, adults emerged on 8.vi–15.vii.2012 (269 ♀ 284 ♂, some probably in BMNH) ; Lleida, Alfes, 41.54843°N 0.65482°E, ex fruits of A. fistulosus , collected on 21.vi.2011, adult emerged on 25.vi.2011 (A. Ribes) (1 ♂) ; La Granja d'Escarp, 90 m, 41.40481°N 0.33695°E, ex fruits of A. fistulosus , collected on 20.iii.2012, adults emerged in 2012 (A. Ribes) (5 ♀ 6 ♂) ; Tarragona, García , 75 m, 41.13127°N 0.65186°E, ex fruits of A. fistulosus , collected on 7.vi.2012, adults emerged on 18–28.vi.2012 (A. Ribes) (1 ♀ 3 ♂) .

Etymology. Named after the host plant.

Condition of holotype.Complete specimen glued by right ventrolateral mesosoma and gaster to card point pinned over card rectangle.

Description of females from the type series ( Fig. 29A ). Length excluding ovipositor 1.7–2.1 mm, ovipositor sheaths length 0.6–0.7 mm. Head, mesosoma and gaster coppery, tegulae yellow; antennal scape brown, weakly metallic, with extreme base yellow, flagellum dark brown; wings hyaline, venation yellowish brown; legs with coxae coloured as body, femora metallic with yellow apices, tibiae testaceous yellow sometimes with brownish darkening medially, tarsi with 3 or 4 basal segments whitish, segment 5 and pretarsus darkened.

Head 1.20–1.26× as broad as mesoscutum, in dorsal view 1.8–1.9× as broad as long ( Fig. 29B ); temples 0.35–0.37× as long as eye; POL 2.4–2.55× as long as OOL, OOL 1.5–1.7× as long as posterior ocellus diameter; occipital carina present but fine. Eyes 1.5–1.6× as long as broad, separated by their length, with very short and sparse pilosity. Head in front view oval, 1.1–1.2× as broad as high ( Fig. 29C ); genae rounded, converging; malar space 0.38–0.42× length of eye, malar sulcus straight; mouth opening 2.20–2.27× as wide as malar space; lower face shiny with weak, irregular reticulate sculpture and conspicuous piliferous punctures, setae conspicuous, whitish and slightly flattened; scrobal depressions finely reticulate.

Antenna ( Fig. 29D ) 11263; scape not reaching anterior ocellus, 0.66× as long as eye and about 4.5–5.0× as long as broad; pedicel plus flagellum about 0.95× breadth of head, pedicel less than twice as long as deep; anelli transverse, A1 about 2× and A2 about 3× as broad as long; funicle segments slightly transverse, F1 about 1.1× as stout as pedicel and subquadrate (in small specimens almost anelliform, 1.3–1.6× as broad as long), and F6 1.3× as stout as F1, F2–F6 progressively broader with F6 1.2–1.5× as broad as long; clava slightly broader than F6, about 2.4× as long as broad and half length F1–F6; flagellar sensilla in a single row on each segment, setae dense and adpressed.

Mesosoma in dorsal view 1.6–1.7× as long as broad ( Fig. 29E ), in lateral view 1.5–1.6× as long as deep with propodeum sloping at about 45° to plane of mesoscutum-mesoscutellum ( Fig. 29A ); pronotum 0.25–0.3× length of mesoscutum with a distinct collar rounded into the strongly sloping anterior part; mesoscutum 1.35–1.45× as broad as long, dull with fine and dense reticulation which anteriorly is arranged in more or less semicircular transverse arcs, notauli shallow posteriorly reaching margin slightly laterad of axillar grooves, setae short, decumbent and inconspicuous; mesoscutellum almost 1.1× as long as broad, frenal area not defined, reticulately sculptured with posterior half having areoles slightly broader than those on mesoscutum and with more distinct, suberect pale setae; postscutellum reticulate; propodeum medially 2.0–2.3× as long as postscutellum, almost 0.3× as long as mesoscutellum, very weakly reticulately sculptured with a fine median carina indicated in anterior third, callus with long pale setae, spiracles small and separated from metanotum by half a diameter. Metapleuron with short hairs on lower half; mesepimeron glabrous. Metacoxa with short, adpressed setation dorsally, 2 or rather more times as long as deep; pro- and metafemora somewhat broadened (respectively 3.1–3.6 and 3.0–3.3× as long as broad), metafemur with a shallow, ventral, subapical notch; metatibia with longer inner apical spur about 0.4× as long as basitarsus and shorter than apical width of tibia, the outer spur short, less than half as long as the inner spur.

Fore wing ( Fig. 29A ) 2.2–2.35× as long as broad; costal cell about 12× as long as broad, its lower surface with two complete rows of setae and with basal and apical thirds more extensively setose, upper surface with a row of 6–8 setae at apex; basal fold setose, basal cell closed below and with several setae on upper surface behind submarginal vein; speculum closed below; ratio costal cell: marginal vein: stigmal vein: postmarginal vein as 200:84:31:41, stigma with long uncus.

Metasoma. Gaster ovate, excluding ovipositor sheaths about 1.8× as long as broad, 1.2× as broad as mesosoma, 1.3–1.4× as long as mesosoma, almost or quite as long as head plus mesosoma; hypopygium reaching almost or quite three-quarters of gaster length; GT1 occupies about 0.27× length of body of gaster with posterior margin medially incised, GT2 and GT3 with posterior margins slightly emarginate; ovipositor sheaths 0.55–0.67× length of body of gaster and 1.25–1.35× length of metatibia.

Male. Length 1.65–2.0 mm. Antennal scape with basal two-fifths of ventral surface yellow, mesothoracic dorsum more green than in female with copper colour limited to central parts, legs with yellow colouration brighter and more extensive than in female. Antenna ( Fig. 29F ) with scape 3.4–4.1× as long as broad, 0.6× length of eye; funicle segments relatively shorter than in female, F1 1.55–1.67× as broad as long, rather narrower than pedicel; F3 1.3× as broad as long. Pro- and metafemora broader than in female, 2.36× and 2.63× as long as broad respectively. Gaster almost twice as long as broad, 1.15× as long as mesosoma and 0.87× as long as head plus mesosoma.

Recognition. Idiomacromerus asphodeli belongs to the group of species of Idiomacromerus which were previously segregated in Liodontomerus Gahan and are characterized by the antennal clava lacking a hyaline apical process, the metatibia with two apical spurs, a relatively short marginal vein (less than half as long as costal cell), pronotum with a distinct collar and thorax dorsally with dense reticulate sculpture. Within this group I. asphodeli is distinguished by having 2 (not 3) anelli, an entirely metallic mesothorax with strong coppery tints (at least on the dorsum), clear wings and an ovipositor which is shorter than the gaster but more than half as long. I. asphodeli shares these characters with I. papaveris (Förster, 1856) and I. centaureae (Askew & Nieves-Aldrey, 1988) , which are parasitoids in galls of Cynipidae , but the mesosoma of I. asphodeli is more slender than in the two cynipid parasitoids (at least 1.6 times compared with not more than 1.5 times as long as broad), the tegulae are yellow and not darkened, and the lower face of I. asphodeli has very distinct piliferous punctures. In addition, the occipital carina is present, although weak, in I. asphodeli but usually absent in other Idiomacromerus species except I. papaveris in which it is exceedingly weak. Other known Idiomacromerus parasitoids of Bruchophagus are I. perplexus (Gahan, 1914) and I. pannonicus (Ruschka, 1923) in leguminous seeds, but these lack an occipital carina, and in addition I. pannonicus has three anelli and I. perplexus has a dark tegula and yellowish scape.

Distribution ( Fig. 38 ). Idimacromerus asphodeli was reared only from samples of A. fistulosus seeds collected in northern Spain and it is notable that it was not collected in southern France (Languedoc-Roussillon) where A. fistulosus and its two associated species of Bruchophagus were found. Furthermore, it was found in only four of the sixteen Spanish samples of A. fistulosus seeds, most specimens of I. asphodeli emerging from samples from coastal areas of Spain, and it was present only in low numbers in samples from inland sites in Lleida.

Biology. Trophic relationships ( Fig. 43 ). Idiomacromerus asphodeli was reared in very large numbers from seeds of A. fistulosus infested by B. gijswijti and possibly by B. lecomtei . This host-parasitoid relationship was confirmed by rearing isolated seeds and subsequent seed dissection. It is possible, however, that I. asphodeli utilises additional hosts living in fruits and stems of A. fistulosus .

Phenology. Idiomacromerus asphodeli is bivoltine, the first generation attacking hosts in spring in fresh fruits and emerging as a second generation of adults between early June and mid-July from seeds formed earlier the same year. It is likely that these second generation females oviposit in seeds containing Bruchophagus in the remaining fruits which are dry and still attached to the asphodel flower spikes, and their progeny overwinter as fully grown larvae to emerge in the following spring and oviposit in the first fresh fruits attacked by Bruchophagus .

Sex ratio. The sex ratio is approximately even; in a total of 651 reared specimens, 48.5 percent were females and 51.5 percent males.

Figures

FIGURES 29A–F. Idiomacromerus asphodeli Ribes sp. n., paratypes ex A. fistulosus from Vinaròs, Castellòn, Spain. A–E, ♀. F, ♂. A, habitus. B, head in dorsal view. C, same in frontal view. D, antenna. E, mesosoma in dorsal view. F, antenna.

FIGURE 38. Distribution map of Eupelmus confusus, E. microzonus (only the occurrence of these two Eupelmus species on asphodels shown), Idiomacromerus asphodeli, Pteromalus tethys and Puklina depilata.

FIGURE 43. Trophic web of A. fistulosus. Horizontal scale bars proportional to the numbers of reared specimens examined that are indicated in the bars. Arrows pointing out the direction of the trophic relationships: from phytophagous Bruchophagus spp. to the asphodel and from parasitoids to chalcid hosts.