Isodromus

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1 Head and body all dark (face yellow in male) ..….………………………………..……… niger
1’ Head and body more extensively yellow …….…………………………..……….……….…. 2

 

2(1) Fore wing hyaline ………………………………………..………….………..……… iceryae
2’ Fore wing with distinct dark spot on disc …..………………………………….…………….. 3

 

3(2)  Vertex wider, ocelli forming equilateral triangle; malar sulcus present; mid- and hind tarsi dark ……………………………………………………………..….. sp. 1
3’  Vertex narrower, ocelli forming acute triangle; malar sulcus absent; mid- and hind tarsi white, except for apical 1-2 segments ………………… puncticeps

 

Sp. 1: Sierra (RLZC)

 

Described Nearctic species and distribution

atriventris Ashmead, 1900: CAN (ON, QC); USA (FL, MA, VA)
iceryae Howard, 1887: USA (CA, DC, FL, KS, LA, MD, MO, NC, SC)
montanus Slosson, 1895: USA (CO, NH)
niger Ashmead, 1900: USA (CA, DC, MA, UT, WA, WI)
puncticeps (Howard, 1885): USA (CA, DC, FL, VA)
vinulus (Dalman, 1820): CAN (PE)

 

Remarks

Timberlake (1919) presented a world wide key to species that is still good for the described Nearctic fauna. There is a single damaged specimen (UCR) from Yolo County, labelled I. puncticeps, that matches the label data that Timberlake (1919: 190) reported. However, this specimen does not appear to match the original description. But I there are many other specimens from northern California (EMEC, RLZC) that do match the description of this species. A single specimen from Tulare County (CAS) tends to key out to I. niger, but is not  as dark – this specimen was recovered from a flume, so perhaps the continued immersion in water resulted in a washed-out coloration.

 

References

Ashmead, W. H. 1900. On the genera of the chalcid-flies belonging to the subfamily Encyrtinae. Proceedings of the United States National Museum 22: 323-412.
Dalman, J.W. 1820. Försök till Uppställning af Insect-familjen Pteromalini, I synnerhet med afseen de på de I Sverige funne Arter (Fortsättning). Kungliga Svenska Vetenskapsakademiens Handlingar 41: 123-174, 177-182, 340-385.
Howard, L.O. 1885. Descriptions of North American Chalcididae from the collection of the U.S. Department of Agriculture and of Dr. C.V. Riley, with biological notes. [First paper]. Bulletin of United States Department of Agriculture, Bureau of Entomology 5: 1-47.
Howard, L.O. 1887. Report of the entomologist. Report of the United States Department of Agriculture, 1886: 488.
Slosson, A.T. 1895. The season on Mt. Washington. Entomological News 6: 276-280.
Timberlake, P.H. 1919. Revision of the parasitic chalcidoid flies of the genera Homalotylus and Isodromus Howard, with descriptions of two closely related genera. Proceedings of the United States National Museum 56: 133-194.