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Aprostocetus Westwood, 1833
 
   
A. venustus, male A. hibus, female
  A. venustus, female
     
   
 
 
     
     

Distribution

     

Biology

     

Comments

     
       
           

Classification

 

Subfamily

Tribe

Tetrastichinae

Tetrastichini

 

           
 
 
 

Diagnosis

 


   
 

Fore wing with submarginal vein (SMV) with 2 or more setae dorsally. Postmarginal vein (PMV) reduced, less than 0.5 the length of the stigmal vein (STV), or absent.
Antenna of female with anelli discoid to laminar, usually 4, rarely 3 or 2; funicle 3-segmented. Male antenna with plaque on scape quite large and with funicle 4-segmented. Club most often with 3 segments. In almost all males, each funicular segment bears a compact subbasal whorl of moderately long to very long dark setae. Male scape sometimes swollen.
Anterior margin of clypeus bidentate. Mandible tridentate. Malar sulcus present, usually straight or just weakly curved, rarely with fovea below the eye.
Thorax with pronotum usually short and without a transverse carina. Notauli present and complete. Midlobe of mesoscutum with a single row of adnotaular setae just mesal to the notaulus. Scutellum with 2 pairs of setae and with 2 pairs of longitudinal lines. Mid lobe of mesoscutum with or without a median line.
Median carina usually present; plicae and paraspicular carinae absent. Propodeum with a raised lobe of the callus, which partially overhangs the outer rim of the spiracles.
Cercal setae unequal in length, with one being distinctly longer than the others and sinuate.
Colour of the body metallic or non metallic, with or without pale markings.
Ovipositor usually projecting at least slightly, sometimes very far, in rare case even longer than the body.

 
         
     
 
 

Distribution


 

Aprostocetus, cosmopolitan in distribution, is a very large genus: it is the largest genus in the Tetrastichinae and one of the largest of chalcids (Noyes, 2001).

         
 
 

Biology

     

Aprostocetus displays a wide range in host and biology.
Many species of the subgenus Aprostocetus are primary parasitoids of hosts in plant galls, as Diptera Cecidomyiidae in particular, but also Hymenoptera Cynipoidea, Coleoptera, Coccoidea, and eriophyid mites. Moreover, some species are occasional parasitoids of Diptera and Lepidoptera leafminers.
Species of Chrysotetrastichus are egg parasitoids of Coleoptera Chrysomelidae.
Coriophagus species are egg parasitoids of Hemiptera Cicadellidae and Miridae.
Species of Ootetrastichus are egg parasitoids of Hemiptera Cicadellidae and Delphacidae, Orthoptera Gryllidae, Odonata and Coleoptera Dytiscidae.
Quercastichus species are parasitoids of gall-forming Cynipidae.
Finally, species of Tetrastichodes are endoparasitoids of cockroach oothecae (Blattodea) (Graham (1987); Boucek (1988); La Salle, 1994).

       
                                       
 
 

Comments

 

Aprostocetus belongs to the subfamily of Tetrastichinae by having female funicle 3 and male 4-segmented, notauli complete, ventral plaque on male scape and postmarginal vein reduced.
Graham (1987) divided this large genus in 5 subgenera: Aprostocetus Westwood, Chrysotetrastichus Kostjukov, Coriophagus Graham, Ootetrastichus Perkins and Tetrastichodes Ashmead; La Salle (1994) recognised another one: Quercastichus.
Aprostocetus may be easily confused with Baryscapus: useful characters to distinguish them are the raised lobe of the callus (partially covering the outer rim of the spiracle in Aprostocetus) and the cercal setae (not all subequal with one distinctly longer and sinuate in Aprostocetus). Moreover, Aprostocetus may be confused with Quadrastichus that has similar cercal setae; however, Quadrastichus has only one single setae on submarginal vein, while Aprostocetus has at least 2. Finally, Minotetrastichus is another genus very close to Aprostocetus. It differs in having the clypeal margin weakly lobed or truncate and the propodeal spiracle small, circular and separated from the metanotum by at least its own diameter. It also differs by having the propodeal spiracle with its entire rim exposed and having the two longest cercal setae subequal in length and straight or just slightly curved (Graham, 1987, 1991; La Salle, 1994; Schauff et al., 1998).
A detailed key of the genus is provided for European species (Graham, 1987).

                       
                                                             
                         
 
                                                             
     
 
 

 

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