Microterys

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1 General color yellow; frontovertex length about 4x width; F4-6 white; scutellum distinctly convex; metasoma mostly yellow ……….…………..…………….. nietneri
1′ General color darker, body ranging from light orange to bronzy or green; frontovertex length rarely more than 3x width; F4 dark; scutellum usually much flatter; metasoma usually dark ………………………………………………………………………….. 2

2(1) Mesonotum generally orange, sometimes indistinctly infused  .……..…………..… 3
2′ Mesonotum darker, mostly bronzy, or axillae all dark ………….…………………….. 5

3(2) F6 black ………………………………………….……………………….. mazzanini
3′ F6 light ………………………………………………………………………………… 4

4(3) Forewing with 2 hyaline bands ………………………………………………… sp. 1
4′ Forewing with 1 hyaline band …………………………………………………….. sp. 4

5(3) Forewing with 2 hyaline bands …………………………………………..………… 6
6′ Forewing with 1 hyaline band ………………………………………….………………. 8

6(5) Oral margin above concolorous with face; apical hyaline band completely interrupted ………………………………………………………………………… sp. 2
6′ Oral margin above darker than face; apical hyaline band continuous or only partially interrupted …………………………………………………………………..….…… 7

7(6) F6 dark; ocelli forming equilateral triangle …………………………………yolandae
7′ F6 light; ocelli forming acute triangle ………….………………..…………. xanthopsis

8(6) Mesopleuron darkened posteriorly …………………………………..……… sylvius
8′ Mesopleuron uniformly lightly colored ……………….……………………………… 9

9(8) Oral margin above darker than face; scape completely dark …………….…….. sp. 5
9′ Oral margin (mostly) concolorous with face; scape light basally …………………… 10

10(9) Ocelli separated by distance smaller than their diameters; face with darkened area between toruli …………….… sp. 6
10′ Ocelli separated by distance greater than their diameters; face light …………….… 11

11(10) Mesonotum dark bronzy …………………………………………….. physokermis
11′ Mesonotum metallic green  ………………………..…………………………….. sp. 3

.

Sp. 1: Contra Costa, Imperial, Inyo, San Bernardino, San Diego, Santa Clara, Stanislaus,Tulare (CAS, RLZC, UCD, UCF, UCR, USNM)
Sp. 2: Kern (RLZC) (only 1 specimen)
Sp. 3: El Dorado (RLZC) (only 1 specimen)
Sp. 4: Los Angeles, Santa Barbara (LACM, SBNHM, UCR) (only 4 specimens)
Sp. 5: Madera (LACM) (only 2 specimens)
Sp. 6: Inyo, Sonoma (EMEC) (only 2 specimens)

 

Described Nearctic species and distribution

cincticornis Ashmead, 1900: USA (IL, MA, NH)
cyanocephalus (Dalman, 1820): CAN (ON)
fuscicornis (Howard, 1885): USA (MD, MN)
interpunctus (Dalman, 1820): Greenland
kotinskyi (Fullaway, 1913): Bermuda, USA (FL)
lachni (Ashmead, 1886): USA (FL)
mazzinini Girault, 1917: USA (CA)
montinus (Packard, 1881): USA (CO, NH)
nietneri (Motschulsky, 1859): Probably accidentally introduced into CAN (ON), MEX, USA (CA, FL, IL, NJ, OH, TX)
physokermis Compere, 1926: USA (CA)
potosinus Trjapitzin, 2003: MEX
speciosissimus Girault, 1911: USA (IL)
sublestus (Howard, 1885): USA (CN, FL)
sylvius (Dalman, 1820): CAN, USA (CA)
tessellatus (Dalman, 1820): Greenland
tricoloricornis (De Stafani, 1886): Probably introduced into MEX
xanthopsis Compere, 1926: USA (AZ, CA, UT)
yolandae Compere, 1926: USA (CA)

 

Remarks

I based my key on that of Compere’s (1926), as it still appears to be applicable for the described species from the state (bearing in mind that his “M. flavus” is now M. nietneri, and his “M. titiani” is now M. sylvius), although it may be difficult distinguishing when there are one versus two hyaline bands in the forewing for older specimens I have a short series of specimens collected from Mt. Hamilton (Santa Clara County) that key out to M. physokermes, of which one is almost totally dark, with only the frons and propleura lighter.   Microterys lunatus (Dalman, 1820) was imported into California from Europe for control of Parthenolecanium corni.  Noyes (2016) recorded it from California, citing Noyes & Hayat (1994), but the latter reference, citing Bartlett, 1978, noted that this species had not established here. Similarly, M. okitsuensis Compere, 1926 was imported into California from China and Japan against the same host, but also failed to establish. The situation regarding M. tricoloricornis (De Stefani, 1886) is more complicated. This species was imported to California from a source in Mexico, but failed to establish here (Bartlett, 1978). But I have been unable to determine that species’ status in Mexico. It appears to be a Palearctic species, and I assume it was introduced from there to Mexico, and it is unclear if it became established there, or if the source of the material imported into California was a lab colony. Trjapitzin et al. (2008) postulate that M. nietneri is native to southeast Asia, but has been spread throughout the world by the movements of host plants.

 

References
Ashmead, W.H. 1886. Studies on the North-American Chalcididae with descriptions of new species from Florida. Transactions of the American Entomological Society 13: 125-135.
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.
Bartlett, B.R. 1978. Coccidae. Pp. 57-74 in Clausen, C.P. (ed.). Introduced parasites and predators of arthropod pests and weeds: a world review. United States Department of Agriculture, Agricultural Handbook 480: 545 pp.
Compere, H.1926. New coccid-inhabiting parasites (Encyrtidae, Hymenoptera) from Japan and California. University of California Publications in Entomology 4: 33-50.
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.
De Stefani, T. 1886. Raccolte imenotterologische sui monti di Renda e loro adjacenze. Naturalista Siciliano 5: 112, 138, 168, 181-186.
Fullaway, D.T. 1913. Report of the entomologist. Report of the Hawaii Agricultural Experiment Station. 1912: 26-31.
Girault, A.A. 1911. The chalcidoid parasites of the coccid Kermes pubescens Bogue, with descriptions of two new genera and three new species of Encyrtidae from Illinois. Canadian Entomologist 43: 168-178.
Girault, A.A. 1917. Descriptiones stellarum novarum. Private publication, Glenndale, Maryland: 22 pp.
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.
Motschulsky, V de. 1859. Insectes utiles et nuisibles. Études Entomologiques 8: 169-174.
Noyes, J.S. 2016. Universal Chalcidoidea Database. World Wide Web electronic publication. http://www.nhm.ac.uk/chalcidoids.
Noyes, J.S. & M. Hayat. 1994. Oriental mealybug parasitoids of the Anagyrini (Hymenoptera: Encyrtidae). CAB International, Wallingford, Oxon, UK: 554 pp.
Packard, A.S., Jr. 1881. Descriptions of some new ichneumon parasites of North American butterflies. Proceedings of the Boston Society of Natural History 21: 18-38.
Trjapitzin, V.A. 2003. A new species of the encyrtid genus Microterys Thomson (Hymenoptera, Encyrtidae) from Mexico and a key to species of the M. amamensis Azim group. Entomologicheskoe Obozrenie 82: 767-770.
Trjapitzin, V.A., Ruiz-Cancino, E. & Coronado-Blanco, J.M. 2008. Microterys nietneri (Motschulsky, 1859), parasitoide eficiente de Coccidae, especialmente en citricos. Serie avispas parasíticas de plagas y otros insectos 5: 114 pp.