Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua

FNZ 13 - Encyrtidae (Insecta: Hymenoptera) - Diagnostic Characters

Noyes, JS 1988. Encyrtidae (Insecta: Hymenoptera). Fauna of New Zealand 13, 192 pages.
( ISSN 0111-5383 (print), ; no. 13. ISBN 0-477-02517-X (print), ). Published 09 May 1988

Diagnostic Characters

Unless otherwise stated in the captions, all figures were drawn directly from slide-mounted material using a drawing tube attachment on a compound microscope. Relative measurements can therefore be taken straight from these figures. Such measurements must not be made where the points of reference were not equidistant from the objective of the microscope when the drawings were made, e.g., width of scape (the scape is rarely absolutely flat on a slide-mounted specimen), distance of antennal toruli from mouth margin, length of malar space, eye length, POL and OOL, etc. These measurements can be made reliably only from dry, card-mounted specimens.

Head (Figures 1 - 3)

ANTENNAL CLUB. This is composed of from one to three segments; if more than one is present then these are separated by complete or partial sutures and are not as distinctly separated as the funicle segments. The sensory plate on the ventral surface of the club often becomes inflated during slidemaking, and any oblique truncation may not be clearly visible. For this reason it is better to ascertain the presence or absence of an oblique or transverse truncation of the club using dry, card- mounted specimens.

ANTENNAL FUNICLE. This excludes the anellus ("false ring-joint" of Timberlake 1922b, pp. 168 and 172), which may be present or absent but is almost always hidden by the pedicel in card-mounted specimens. In the encyrtids the anellus never bears setae, whereas funicle segments always bear setae.

EYE. Measurements of length and width are the maximum and minimum diameters respectively; the points from which the measurements are taken should be equidistant from the objective of the microscope (i.e., both in focus simultaneously).

FRONTOVERTEX. The width is measured across the anterior ocellus or at its narrowest point, whichever is stated in the text.

HEAD DEPTH. The shortest distance from the anteriormost part of the head to the occipital margin when the head is viewed in profile.

HEAD WIDTH. The maximum width of the head in facial view.

MALAR SPACE. The minimum distance between the eye and the mouth margin.

MALAR SULCUS. The line joining the lower eye margin to the mouth margin; often absent, but indicated by a slight change in sculpture.

MANDIBLES. The dentition can vary as follows: without teeth (Figure 164); with one acute tooth (Figure 105); two acute teeth (Figures 99, 233, and 254); one tooth and a broad truncation (Figures 24, 275, and 279); two teeth and a truncation (Figures 6 and 17); two acute teeth and an obtuse upper tooth (Figures 9 and 30); three acute teeth (Figures 128, 217, and 260); or four teeth (Figures 95 and 195). The distinctions are often very obscure, for instance between two teeth and a truncation, two acute teeth and an obtuse upper tooth, and three acute teeth. Similarly for the difference between one tooth and a truncation and two teeth and a truncation, three and four teeth or two teeth and a truncation, and four teeth.

OOL. The minimum distance between the eye margin and the nearest posterior ocellus.

OPL. The minimum distance between a posterior ocellus and the occipital margin.

POL. The minimum distance between the posterior ocelli.

Thorax (Figures 1 and 2)

FOREWING (Figure 1).

BASAL CELL: the area bounded by the linea calva, the submarginal vein, and a line of setae, usually present, which is separated from the posterior wing margin by a narrow, naked strip.

FILUM SPINOSUM: a series of peg-like bristles, distinctly stouter than adjacent setae, on the distal margin of the linea calva.

FOREWING LENGTH: measured from the proximal part of the costal cell to the wing apex.

FOREWING WIDTH: measured across the greatest width of the wing at right angles to the anterior wing margin.

LENGTH OF MARGINAL SETAE: the length of the longest marginal setae.

LINEA CALVA: an oblique, hairless line extending from just below the marginal and stigmal veins to the posterior margin of the wing.

MARGINAL VEIN: measured from where the sub-marginal vein reaches the anterior wing margin, or from where the anterior edge of the venation at the junction of the submarginal vein is abruptly angled and not from the subapical hyaline break of the submarginal vein.

PARASTIGMA: a very slight to strong swelling of the apical third of the stigmal vein.

POSTMARGINAL VEIN: length is measured from the distal margin of the junction of the stigmal and marginal veins to its apex; the apex is usually indicated by a single, relatively long, suberect seta.

STIGMAL VEIN: measured from the distal margin of the junction of the stigmal and marginal veins to its apex; there are usually three or four circular sensilla at the apex.

UNCUS: a beak-like process often arising from the apex of the stigmal vein.

MESOPLEURUM. Recent research (Gibson 1986*) has shown the large, modified area below the wings which makes up the greater part of the side of the thorax to be only a part of the mesopleurum.

*NOTE ADDED IN PRESS. Gibson (pp. 699 and 703-704) uses the term 'acropleuron' for this area (Gibson, G.A.P. l986: Mesothoracic skeletomusculature and mechanics of flight and jumping in Eupelminae (Hymenoptera, Chalcidoidea: Eupelmidae). Canadian Entomologist 118: 691-728). For present purposes, however, the term 'mesopleurum' has been employed.

METAPLEURUM. A very narrow strip connecting the hindwing base to the hind coxa; often hidden by the posterior margin of the mesopleurum.

NOTAULAR LINES. Very shallowly impressed, curved lines sometimes present on the mesoscutum. They may be difficult to see in dry-mounted material unless viewed under the correct light conditions.

PROPODEUM. The true first abdominal segment, which has become appressed to the thorax and thus has the appearance of being part of it; length is measured along the midline.

SCUTELLUM. Length is measured along the midline; width excludes the axillae.

Gaster (Figures 1, 2, 4, and 5)

AEDEAGUS. Usually very simple, flat and gradually tapering distally; occasionally spatulate or with various processes subapically. Length is measured from the proximal parts of the apodemes (the rods at the base of the aedeagus) to its apex.

CERCI. Relative position is measured in dry-mounted material; if measured in material that has been in alcohol, critical-point dried, or slide-mounted the gaster may become distended, and the cerci will be positioned relatively nearer the apex.

DIGITUS. A finger-like process from the side of the distal part of the phallobase, often with from one to four sclerotised teeth or hooks at its apex.

GASTER. The third to twelfth abdominal segments, i.e., excluding the first (propodeum) and second (petiole) segments.

GONOSTYLUS. The third valvula or ovipositor sheath, as seen in slide-mounted material.

HYPOPYGIUM. The seventh abdominal sternite (= fifth gastral sternite). The relative position of the apex is measured in dry-mounted material.

LAST TERGITE. The fused ninth and tenth abdominal tergites (seventh and eighth gastral tergites). Its length is the shortest distance from its apex to an imaginary line connecting the cercal plates.

OVIPOSITOR. Length is measured as shown in Figure 4. The length of the exserted part is measured from the apex of the last tergite in dry-mounted material.

OVIPOSITOR SHEATH. The gonostylus as seen in dry-mounted material.

PARAMERE. A process from the distal part of the phallobase, outside the digitus and often with a single short seta at its apex; sometimes more or less absent.

PARATERGITE. A narrow, sclerotised, membranous strip connecting the outer plates of the ovipositor to the cercal plates and usually also to the last tergite of the gaster. Normally present in the Tetracneminae, but present in only very few Encyrtinae.

PHALLOBASE. A tube-like structure enclosing the base of the aedeagus, sometimes with complex elements distally.

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