Key to the known species of Ichneumonosoma de Meijere

1. Abdomen completely or almost completely yellow to yellow-brown, without narrow black bands on posterior margin of tergites 1–4; scutum with pair of rounded presutural black spots.................................................... 2

- Abdomen with narrow black bands on posterior margin of each of tergites 1–4; scutum with pair of large L-shaped presutural black marks.......................................................................................... 4

2. Thorax only with pair of presutural black spots, other parts entirely yellow (Fig. 3)................... I. consors (Walker)

- Thorax in addition to presutural black spots, also with black spots on pleuron or postsuturally on scutum................ 3

3. Thorax with pair of short black postsutural dorsocentral spots near transverse suture (possibly variable) (Fig. 13); anepisternum with large rounded dorsomedial black mark............................................... I. heinrichi Hering

- Thorax with pair of large round black spots near posterolateral corners of scutum; anepisternum without black markings (Fig. 37)................................................................ I. quadripunctata Chen & Freidberg, n. sp.

4. Head with round polished black spot over ocellar tubercle, dorsomedian portion of occiput and vertex, not extended anterolaterally to eye margin (Fig. 19); pleuron with separate large black marks on anepisternum, katepisternum and meron, and sometimes with small black mark on katatergite; orbital plate sparsely setulose....................... I. imitans (de Meijere)

- Head with triangular polished black mark over ocellar tubercle, dorsomedian portion of occiput and vertex,extended anterolaterlly to eye margin (Fig. 51); pleuron with black band on anepisternum only, katepisternum, meron, and katatergite without black markings; orbital plate finely but densely setulose.................. I. triangularis Chen & Norrbom, n. sp.