Diglyphus isaea (Walker)

Hansson, Christer & Navone, Paolo, 2017, Review of the European species of Diglyphus Walker (Hymenoptera: Eulophidae) including the description of a new species, Zootaxa 4269 (2), pp. 197-229 : 203

Diglyphus isaea (Walker)

Figs 9, 10 , 37 , 59, 60 , 73 , 78

Cirrospilus isaea Walker, 1838: 385 –386, lectotype male in BMNH (type no. 5.2591), examined.

Cirrospilus lycophron Walker, 1838: 449 , lectotype male in BMNH (type no. 5.2607), examined. Synonymized by Bouček & Askew (1968: 70).

Cirrospilus medidas Walker, 1838: 386 , lectotype male in BMNH (type no. 5.2592), examined. Synonymized by Bouček & Askew (1968: 70).

Entedon gracilis Goureau, 1851: 159 , type material not examined. Synonymized by Graham (1963: 179).

Diglyphus bisannulatus Förster, 1861: 38 , type material not examined. Synonymized by Bouček & Askew (1968: 70).

Diglyphus ornatus Förster, 1861: 38 , type material not examined. Synonymized by Bouček & Askew (1968: 70).

Diglyphus clavicornis Walker, 1872: 126 , lectotype male in BMNH (type no. 5.1341), examined. Synonymized by Bouček & Askew (1968: 70).

Elachistus phytomyzae Rondani, 1877: 173 , type material not examined. Synonymized by Bouček (1974: 262).

Solenotus viridis Thomson, 1878: 237 , lectotype female in MZLU. Synonymized by Hansson (1991: 33).

Diglyphus isaea ; Graham, 1959: 178.

Diagnosis. Scape completely dark ( Figs 59, 60 ); legs ( Fig. 37 ): femora dark and metallic with apical ¼–½ white; fore tibia with anterior surface white and posterior surface dark and metallic or dark brown, mid and hind tibiae dark and metallic with apical ¼ –¼ white, males frequently with median part of tibiae pale ( Fig. 78 ), but males with tibiae predominantly dark, as in females, also occur; fore wing speculum with dense setation ( Fig. 73 ); pronotum and mesoscutum with white setae; scutellum green to golden ( Figs 9, 10 ), occasionally reddish; male gaster completely dark ( Fig. 10 ).

Material. Italy: 109♀ 81♂ (PN) . Romania: 3♀ 5♂ ( BMNH) . Sweden: 297♀ 118♂ ( BMNH, MZLU) .

Distribution. Throughout the Holarctic region, also recorded from Brazil, India, New Zealand, Pakistan, South Africa ( Noyes 2016).

Remarks. Diglyphus isaea probably represents the best known species among target parasitoids of leafmining Agromyzidae . However, this species has occasionally been reported also from leafmining Gracillariidae and Nepticulidae (Lepidoptera) ( Navone & Vidano 1983; Schauff et al. 1998; Gonzáles Tirado et al. 1996; Conti et al. 2001; Elekçioğlu & Uygun 2006). Moreover, females of D. isaea are attracted to larvae of Tuta absoluta (Meyrick) ( Lepidoptera : Gelechiidae ) and show predatory behavior vis-a-vis this host under laboratory conditions ( Payer et al. 2015). Some of the reports on Lepidoptera may represent misidentification of the host. For instance, the record of Vidano & Navone (1983) during a heavy infestation of Stigmella malella (Stainton) ( Lepidoptera : Nepticulidae ) probably should be attributed to contemporary but occasional presence of Phytomyza heringiana Hendel ( Diptera : Agromyzidae ) mining leaves on apple trees. Nevertheless, the repeated reports on Phyllocnistis citrella Stainton ( Lepidoptera : Gracillariidae ) seem less questionable because Agromyzidae leaf miners are unknown on Citrus spp. ( Rutaceae ) in Europe and in the Mediterranean basin. Among the specimens examined for this work, four females and two males emerged from P. citrella on Citrus limon (L.) Osbeck in Southern Italy (Legit: L. De Marzo) and they are morphologically indistinguishable from the specimens obtained on agromyzids.

However, the large distribution and wide host spectrum of D. isaea possibly indicate that this actually is a group of morphologically very similar species. Sha et al. (2007) analyzed specimens of D. isaea from China, using the nuclear gene ITS1, and found that there were at least four different species in the material. Even though it is somewhat doubtful what species they analyzed—their specimens had a shiny violet scutellum, which is a character found in neither the type of D. isaea nor in other European material of this species—their investigation shows that further studies are needed to determine if the current concept of D. isaea refers to one or multiple species.

Figures

FIGURE 78. Diglyphus spp., schematic drawings of femora + tibiae from top to bottom: fore, mid and hind leg; scape + pedicel. Species are arranged according to colour of the scape, from pale to dark, and then according to colour of the legs, also from pale to dark.

FIGURES 9 – 16. Diglyphus spp., length of body, habitus in dorsal view: 9, D. isaea (Walker) female, 1.7 mm; 10, D. isaea male, 1.3 mm; 11, D. minoeus (Walker) female, 1.7 mm; 12, D. minoeus male, 1.7 mm; 13, D. poppoea Walker female, 1.4 mm; 14, D. poppoea male, 1.3 mm; 15, D. pusztensis (Erdös & Novicky) female, 1.4 mm; 16, D. pusztensis male, 1.2 mm.

FIGURES 37 – 42. Diglyphus spp., length of body, female habitus in lateral view: 37, D. isaea (Walker), 1.7 mm; 38, D. minoeus (Walker), 1.8 mm; 39, D. pachyneurus Graham, 1.9 mm; 40, D. poppoea Walker, 1.2 mm; 41, D. sabulosus Erdös, 1.7 mm; 42, D. pusztensis (Erdös & Novicky), 1.4 mm.

FIGURES 49 – 60. Diglyphus spp., head & antenna in lateral view: 49, D. albiscapus Erdös female; 50, D. anadolucus Doganlar female; 51, D. anadolucus male; 52, D. begini (Ashmead) female; 53, D. begini male; 54, D. chabrias (Walker) female; 55, D. chabrias male; 56, D. crassinervis Erdös female; 57, D. eleanorae Graham female; 58, D. eleanorae male; 59, D. isaea (Walker) female; 60, D. isaea male.

FIGURES 72 – 77. 72 – 73, Diglyphus spp., right fore wing, females: 72, D. chabrias (Walker); 73, D. isaea (Walker). 74 – 77, Diglyphus spp., right wing-pair, males: 74, D. anadolucus Doganlar; 75, D. crassinervis Erdös; 76, D. pachyneurus Graham; 77, D. clematidis sp. nov.