Megastigmus Dalmann, Annals 1820
Creators: name: Roques, A.
name: Skrzypczyńska, M.
Publisher: name: Zenodo
Year: 2003
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Torymidae
Megastigmus

description: Key to males of Megastigmus native and introduced to the West Palearctic region   
1 Thoracic dorsum metallic-coloured (green, bluish or violet) at least partly; antenna inserted just above lower ocular line; species living within galls...... 2  
– Thoracic dorsum yellow and/or brown to black, without any metallic-coloured part; antenna inserted distinctly well above lower ocular line; species living within seeds. 4  
 2 Forewing stigma elongate; body 5–7 mm long.... M. stigmatizans (Fabricius)   
– Forewing stigma rounded or short-oval; body less than 5 mm long (max.: 4 mm). 3  
 3 Mid-lobe of mesoscutum finely rugulose; pronotum with eight rows of hairs...................... M. dorsalis (Fabricius)   
 – Mid-lobe of mesoscutum with dense transverse striae; pronotum with 16 rows of hairs or more............. M. almusiensis Doǧanlar   
 4 Forewing stigma surrounded by a distinct infuscated area (figure 74)....................... M. nigrovariegatus Ashmead   
– Stigma not surrounded by a distinct infuscated area......... 5  
5 Frenal area strongly impressed (figure 153) or with numerous rounded carinae (figures 149, 154, 160)................... 6  
– Frenal area mostly smooth (figure 151) or with only a few longitudinal carinae (e.g. figure 146)..................... 11  
 6 Thorax usually entirely yellow.......... M. pistaciae Walker   
– Thorax with some black parts at least............. 7  
 7 Pilosity on thoracic dorsum mostly pale, even on yellow maculae; frenal area strongly impressed but without distinct carinae (figure 153)...... M. pinus Parfitt   
– Pilosity on thoracic dorsum mostly black; frenal area with distinct carinae (figures 149, 160)...................... 8  
8 Pilosity on lower face (below antenna) mostly pale; thoracic dorsum not entirely black; stigma broadly oval, less than 1.5× as long as broad (max: 1.4×) (figure 73) 9  
– Pilosity on lower face (below antenna) mostly dark; thoracic dorsum entirely black; stigma elongate, more than 1.5× as long as broad (min.: 1.6×) (figures 76, 84).. 10  
 9 Thorax black with more or less extended yellow spots on sides and posterior margin of pronotum, outer surface of mesoscutum, tegula, prepectus and mid-part of metanotum; propodeum entirely black, with a distinct median carina.. M. milleri Milliron   
 – Thorax orange yellow except black sutures along prepectus, tegula, acropleuron and lateral panel of metanotum; propodeum orange yellow with a triangular black patch in the middle, without central but with lateral carinae (figure 161)....................... M. transvaalensis (Hussey)   
 10 Hind coxa black; frenal area with coarse longitudinal carinae (figure 160); aedeagus smaller than digitus (figure 122)......... M. suspectus Borries   
 – Hind coxa yellow with black markings; frenal area without coarse longitudinal carinae but rounded wrinkles (figure 145); aedeagus longer than digitus (figure 114)...................... M. pinsapinis Hoffmeyer   
11 Mesoscutum and/or scutellum predominantly yellow or brownish yellow.... 12  
– Mesoscutum and/or scutellum predominantly black......... 19  
12 Forewing stigma with upper part of stigmal vein 0.3× as long as stigma length at more (figures 70, 86).................. 13  
– Forewing stigma with upper part of stigmal vein longer than 0.3× stigma length (min.: 0.4×) (figures 75, 82)............... 17  
13 Thoracic dorsum mostly brownish black, only pronotum more or less yellowish.. 14  
– Thoracic dorsum mostly yellow (pale to brownish)......... 15  
 14 Propodeum without distinct median longitudinal carina; forewing stigma ovoid, with a short uncus, 2× shorter than upper part of stigmal vein (figure 72)....................... M. bipunctatus Swederus   
 – Propodeum with a median longitudinal carina; forewing stigma with a long uncus, about as long as upper part of stigmal vein....... M. rosae Boucĕk   
 15 Forewing stigma with uncus smaller than upper part of stigmal vein (figure 70)...................... M. amicorum Boucĕk   
– Forewing stigma with uncus as long as upper part of stigmal vein or longer (figures 69, 86)...................... 16  
 16 Body entirely dirty yellow; frenal area with distinct longitudinal carinae (figure 162); upper part of stigmal vein very short, more than 10× smaller than stigma length (figure 86); aedeagus elongate, digitus with six teeth (figure 8). M. wachtli Seitner   
 – Body brownish yellow with a few brown to black markings on axilla, mesoscutum and propodeum; frenal area without distinct carinae (figure 145); upper part of stigmal vein only 4–5× smaller than stigma length (figure 69); aedeagus short and conical, digitus with three teeth (figure 107)..... M. aculeatus (Swederus)   
 17 Thoracic dorsum mostly brownish black, only pronotum more or less yellowish...................... M. pictus (Förster)   
– Thoracic dorsum mostly yellow (pale to brownish)......... 18
description: Published as part of Roques, A. & Skrzypczyńska, M., 2003, Seed-infesting chalcids of the genus Megastigmus Dalman, 1820 (Hymenoptera: Torymidae) native and introduced to the West Palearctic region: taxonomy, host specificity and distribution, pp. 127-238 in Journal of Natural History 37 (2) on pages 143-144, DOI: 10.1080/713834669, http://zenodo.org/record/5275477