Prionomitus, Mayr, 1876

Noyes, John Stuart, 2023, ENCYRTIDAE OF COSTA RICA (HYMENOPTERA: CHALCIDOIDEA), 4 Subfamily Encyrtinae: tribes Arrhenophagini, Habrolepidini, Cerapterocerini, Cheiloneurini, Trechnitini, Cercobelini, Polaszekiini, Protyndarichoidini, Gahaniellini and Syrphophagini (part), mainly primary parasitoids and hyperparasitoids of Coccoidea and Psylloidea (Hemiptera), Taxonomic Monographs on Neotropical Hymenoptera (Oxford, England) 2 (11), pp. 1-921 : 553-554

Genus PRIONOMITUS Mayr

Prionomitus Mayr, 1876:701 . Type species: Encyrtus chlorinus Dalman , by monotypy.

Female. Length about 0.9-2.0mm.

Body generally metallic green, often with purplish markings on face.

Antenna with funicle 6-segmented; clava 3-segmented; mandible with one tooth and a broad, slightly concave truncation.

Mesoscutum with a characteristic posterolateral depression or invagination anterior to tegula; fore wing with marginal vein very short, very nearly punctiform, postmarginal vein distinct at least about half as long as stigmal vein.

Gaster with hypopygium extending past apex of last tergite, often enclosing ovipositor to its apex.

Male. Length about 0.9-1.8mm.

Generally similar to female but antenna with segments elongate, but asymmetric, proximal segments subserrate, all segments with whorls of long setae each at least about 3X as long as diameter of segments; phallobase with digiti well-developed and each with from 2 to 4 apical teeth.

HOSTS AND BIOLOGY. Of the described species, hosts are known only for P. mitratus (Dalman) and tiliaris (Dalman) . In the Palaearctic region these species have been recorded from nymphs of Cacopsylla Ossiannilsson and Livilla Curtis and in the Nearctic region from Cacopsylla , Ceanothia Heslop-Harrison , Euglyptoneura Heslop-Harrison and Pexopsylla Jensen ( Hemiptera : Psyllidae ). The life history and host preferences in southern France have been described for P. mitratus by Delvare, et al. (1981), Nguyen & Delvare (1982) and Delvare (1984). The eggs are normally deposited in the fourth instar of one of five species of Psylla Geoffroy and adult parasitoids emerge from the fifth instar. There are normally three generations of the parasitoid per year and the winter is passed in the adult stage with oviposition commencing the following year in May. The deposited egg has a long peduncle which remains protruding through the integument of the host, but there is no aeroscopic plate. Development of the embryo lasts about 2.5 days at 20°C. The eclosed larva lies with its head towards the posterior of the host and has 13 postcephalic segments. The first two larval instars are probably apneustic and remain attached to the integument of the host via the remains of the egg. The third instar is free and has 7 pairs of spriracles located in segments II to VII (Delvare, et al., 1981). The fourth instar has an additional pair of spiracles on segment IX. The fifth instar fills almost the whole body cavity of the host and has spiracles on each of segments II to X and in addition seven pairs of papillary organs on the head. At this point, about 12-13 days after oviposition, the host becomes mummified and after a further 18-20 days the adult parasitoid emerges.

DISTRIBUTION. The genus is found throughout the Holarctic region, Pakistan and central America ( Mexico and Costa Rica) ( Noyes & Hanson, 1996; Noyes 2019; Trjapitzin, 1989).

BIOCONTROL. See under Prionomitus mitratus below.

COMMENTS. Species of Prionomitus are frequently mistaken for Psyllaephagus , but females can be distinguished by the hypopygium extending to the apex of the gaster and enclosing the ovipositor nearly to its apex and both sexes can be distinguished on the presence of the posterolateral depression on the mesoscutum anterior to each tegula. In Psyllaephagus the hypopygium rarely reaches more than three-quarters along the gaster and never encloses the ovipositor to its apex and there are never posterolateral depressions on the mesoscutum.

IDENTIFICATION. Nine World species, 7 of which are Palaearctic, 1 Holaractic and Neotropical and 1 Neotropical. Trjapitzin (1989) provides a key to 6 of the 8 species known from the Palaearctic region, including mitratus (below).