The Gall Wasp Genus Cynips: A Study in the Origin of Species/Key to Described Cynips

by Alfred Charles Kinsey

KEY TO DESCRIBED CYNIPS

DIAGNOSTIC CHARACTERS OF AGAMIC FORMS. Usually rather large and robust insects with the mesonotum punctate and more or less hairy, usually with complete parapsidal grooves, an undivided or finely divided foveal groove, a hypopygial spine which is large and distinctly broadened nearer the tip (except in short-winged Acraspis) and which terminates in a prominent tuft of long hairs; tarsal claws which are strongly or at least weakly toothed (except in mellea) ; wings long or much reduced, the long wings 1.17 to 1.60 times the body length, the short wings of various lengths down to 0.14 times the body length; the long wings usually with a smoky patch at the base of the cubital cell, sometimes with additional spots or smoky patches in this and other cells. Living (with a few exceptions) in monothalamous, highly separable leaf galls which are usually spherical, with the centrally placed larval cell closely embedded in dense, radiating fibers or more solid, spongy or crystalline material, the galls in some cases of more diverse form, especially in the subgenus Antron. Strictly confined to white oaks. Galls appearing in early summer, the adults maturing early in the fall, but delaying emergence until cold weather, from early winter to early spring of the first year (and successive years in C. fulvicollis). DIAGNOSTIC CHARACTERS OF BISEXUAL FORMS. More slender insects, with the mesonotum largely smooth and naked, the hypopygial spine as in the agamic form but more slender; tarsal claws toothed; wings always long, 1.17 to 1.60 times the body length, less heavily spotted than in agamic forms; the males with one more antennal segment than in the female, with the third segment slightly curved, and with the abdomen long-petiolate. Galls always small, seed-like or bladdery, thin-walled cells in the undeveloped buds of the white oaks. Galls appearing with the opening buds in the spring, the adults maturing within a very few weeks.

1.	Wings always 1.50 times the body length, cells always clear (except fora trace of a blotch at base of cubitus); hypopygial spine rather broad, rather drawn out ventrally. Entirely Old World species.Subgenus Cynips, 4
	Wings from 0.14 to 1.60 times the body length, wing cells clear or spotted, spines various. Entirely American species.2
2.	Hypopygial spine rather broad, but drawn out ventrally (see figs. 175-190); wings normally 1.60 times the body length, or much reduced in length; with a heavy patch and sometimes spots in cubital cell. Pacific Coast species not known east of the Sierras except in southern Arizona.Subgenus Antron, 7
	Hypopygial spine very large, as high as long, extending dorsally as far as or further than ventrally (see figs. 217-224); wing-body ratio 1.50; cubital and discoidal cells always spotted; Pacific Coast species not known east of the Sierras.Subgenus Besbicus, 9
	Hypopygial spine usually more drawn-out and slender (broad in Philonix especially in short-winged forms), the normal wings 1.17 to 1.35 times the body length, but many forms with wings much reduced. Always east of the Sierras, from Mexico to southeastern Canada.3
3.	Wing-body ratio normally 1.17, the wings without spots except for traces of a blotch in the cubitus; second abscissa of radius rather straight, radial cell rather long, wide; the normal spine rather broad but projecting basally; many forms with wings much reduced and the spine much broadened and abruptly truncate posteriorly. Agamic galls of moderate size or small, spherical; bisexual forms in seed-like cells in buds.Subgenus Philonix, 12
	Wing-body ratio normally 1.35; wings with spots and patches in many of the cells; second abscissa of radius well curved, radial cell usually short and broad (see figs. 266-273); the spine rather long and slender, not greatly widened (see figs. 276-286); the wings sometimes reduced. Agamic galls large, strictly spherical, smooth and naked “oak apples”; bisexual forms unknown.Subgenus Atrusca, 13.
	Wing-body ratio normally 1.30, wings largely clear or with smoky patches in the cubital cell; radial cell moderately long and not narrow (see figs. 345-368), normal spine rather slender plough-shaped (see figs. 386-406); or wings reduced, sometimes to mere stubs, and then the spine usually slender, blunt, of uniform width (see figs. 407-429); agamic galls more or less spherical, ellipsoid, or conical, naked, spiny, or woolly, usually thick-walled and compact crystalline internally in all species except mellea; bisexual forms in seed-like cells in buds.Subgenus Acraspis, 16

SUBGENUS CYNIPS

4.	Agamic female with abdomen not more than half again as long as high, with tip of second segment approaching tip of abdomen dorsally; the central European varieties with the mesonotum largely punctate and hairy. Bisexual adults with mesonotum and mesopleura entirely smooth. Agamic galls spherical with considerable spongy tissue inside; bisexual galls seed-like, on twigs or older branches or the main trunk.5
	Agamic female with abdomen fully twice as long as high, with tip of second segment extending two-thirds or less to tip of abdomen; the Central European varieties with the mesonotum largely smooth and naked. Bisexual adults (known for divisa only) with mesonotum roughened anteriorly about parapsidal grooves, the mesopleura with a limited rough spot. Agamic galls spherical, ellipsoid, or elongate club-shaped with very little spongy material inside; bisexual gall (known for divisa only) an irregularly restricted or subdivided cell attached to the edge of a leaf or rarely in buds or on young shoots. 6
	Agamic female with abdomen not more than half again as long as high, with tip of second segment extending three-quarters of way to tip; the mesonotum in part punctate and hairy with a large, smooth and naked area. Agamic gall spherical to ellipsoid with almost no spongy tissue inside. Bisexual forms unknown. C. agama
5.	Agamic female of Central Europe with thorax robust and scutellum rugose, as much so anteriorly as posteriorly; northern European insects with mesonotum smooth. Bisexual females with legs bright, clear yellow. Agamic galls soft, sometimes spotted but not banded; bisexual galls with a shorter purplish or reddish pubescence when fresh. C. folii, 5a
	5a.	Agamic female largely rufous and piceous, mesonotum heavily punctate and hairy; scutellum as rugose anteriorly as posteriorly; length 2.8 to 4.0 mm. Agamic galls up to 30.0 mm. in diameter, spongy, shrivelling, becoming russet brown. Bisexual form as in next variety. Central European. var. folii
		Agamic female largely rufous; mesonotum moderately punctate and hairy; scutellum smoother anteriorly than posteriorly; length 3.0 to 4.4 mm. Agamic gall up to 10.0 mm. in diameter, less spongy, not shrivelling, remaining light brown. Bisexual form as in above variety. Mediterranean Europe. var. flosculi
		Similar to above. On Q. Ilex in Spain. var. ilicicola
		Agamic female almost entirely black; mesonotum largely smooth and naked; scutellum as rugose anteriorly as posteriorly; length 2.1 to 2.7 mm. Agamic galls spongy, shrivelling, becoming russet brown. Bisexual form not known. var. atrifolii
	Agamic female in Central Europe with thorax rather slender and with scutellum smoother especially anteriorly; northern European insects with mesonotum coriaceous or shagreened in places. Bisexual females with legs duller yellow with femora more or less piceous. Agamic galls prominently banded brown-purple. Bisexual galls with a longer, gray pubescence. C. longiventris, 5b
	5b.	Agamic female largely rufous and piceous, mesonotum largely hairy and punctate, anterior parallel and lateral lines prominent, length 2.5 to 3.8 mm. Bisexual form known. More Central European. var. longiventris
		Agamic female nearly black, the mesonotum largely naked, anterior parallel and lateral lines not prominent, length 1.9 to 2.5 mm. More northern European. var. forsiusi
6.	Agamic insect largely brownish rufous and black; tip of second abscissa of radius not enlarged. Agamic gall elongate horn- or club-shaped. Bisexual form not known. Mediterranean area; Q. pubescens. C. cornifex
	Agamic insect largely bright rufous; tip of second abscissa slightly enlarged. Agamic gall superficially spherical but flattened on top and bottom, internally with two cavities. Bisexual form not known. C. disticha
	Agamic insect rufous and piceous (Central Europe) or entirely black (northern Europe), tip of second abscissa prominently enlarged (Central Europe) or not enlarged (northern Europe). Agamic gall strictly spherical. Bisexual insect with mesonotum roughened about parapsidal grooves anteriorly. Bisexual gall an irregularly constricted cell on leaf or in bud. C. divisa, 6a
	6a.	Agamic female rufous and piceous, anterior parallel and lateral lines distinct, tip of second abscissa prominently bent or triangulate, length 2.8 to 4.0 mm. Bisexual form known. More Central European. var. divisa
		Agamic female entirely black, anterior parallel and lateral lines hardly visible, tip of second abscissa not at all enlarged. Bisexual form not known. More northern Europe. var. atridivisa

SUBGENUS ANTRON

7.	Wings long or short; if long, the cubital cell has a basal blotch and numerous spots; galls of various shapes. 8
	Wings always long, cubital cell with basal blotch but no spots; galls more or less spherical, spiny, squash-shaped or vase-shaped; confined to Calif. C. echinus, 7a
	7a.	Agamic female rufous and black to mostly black; several bisexual forms known; galls various. 7b
		Agamic female wholly bright, brownish rufous; the bisexual form not known; galls irregularly cushion-shaped; Q. dumosa; so. Calif. var. dumosae
	7b.	The agamic female bright rufous and black, with the foveal groove slightly rugose; bisexual female with basal segments of antennae yellow or rufous yellow, always with continuous parapsidal grooves.7c
		The agamic female dark rufous and black to mostly black, with the foveal groove smooth or finely rugose; bisexual female (where known) with basal segments of antennae rufous yellow (with parapsidal grooves indistinct anteriorly) or blackish (with continuous grooves).7d
	7c.	Agamic female indistinguishable from var. echinus; bisexual female with two basal segments of antennae yellow, the scutellum rather smooth; agamic gall squash-shaped; Q. lobata, central Calif.var. douglasii
		Agamic female indistinguishable from var. douglasii; bisexual female with four or five basal segments of antennae rufous yellow; agamic galls spherical with many spines; Q. Douglasii, central Calif.var. echinus
	7d.	The agamic female largely dark rufous; bisexual female with antennae rufous yellow basally, parapsidal grooves indistinct anteriorly, scutellum roughly rugose; agamic galls deep bowlor vase-shaped; Q. durata, Q. dumosa; Lake Co. and adjacent Calif.var. schulthessae
		The agamic female very dark rufous and black; bisexual female (where known) with antennae brownish black basally, parapsidal grooves continuous, scutellum distinctly smoothed; agamic galls cushion-shaped or spherical with many spines.7e
	7e.	Foveal groove of agamic female usually smooth at bottom, patches in discoidal cell faint; bisexual female with antennae brownish black basally; galls spherical with many spines; Q. Douglasii; Lake Co. and adjacent Calif.var. vicina
		Foveal groove of agamic female sparingly rugose at bottom, patches in discoidal cell distinct; bisexual form not known; galls cushion-shaped; Q. dumosa; San Bernardino area, Calif.var. mista
8.	Wings full length or reduced to 0.52 or less of body length; galls small, elongate club-shaped; on all Pacific Coast white oaks except Q. chrysolepis and var.C. teres, 8A
	8A.	Thorax and abdomen of normal size, wings long; galls slender, the stalk twice the length of the swollen tip; Q. lobata; Central Valley of Calif.var. clavuloides
		Thorax reduced, dark rufous, hypopygium and legs dark brownish rufous, wings 0.52 of body length, showing bases of veins distal to areolet; galls short, with a short stalk; Q. dumosa, Q. durata; Lake Co. area of Calif.var. hildebrandae
		Thorax reduced, abdomen enlarged, wings short; galls short, the stalk hardly as long as the swollen tip; Q. garryana; Sierras, no. Calif., and Ore.var. teres
	Wings reduced to about 0.80 of body length; galls flattened discshaped, deep bowl-shaped, or pouch-shaped; Q. chrysolepis; Ore., Calif., So. Ariz.C. guadaloupensis, 8a
	8a.	Abdomen smooth and without aciculation; galls disc- or pouchshaped.8b
		Abdomen with scattered aciculation on segments three to six; mature galls deep bowl-shaped; so. Calif, mts.var. patelloides
	8b.	Mesopleuron with shining, naked spot dorsally; galls pouchshaped; San Jacinto Mts.var. insolens
		Mesopleuron entirely punctate and hairy; galls flattened discshaped.var. guadaloupensis

SUBGENUS BESBICUS

9.	Dorsal projections of the hypopygial spine well developed (fig. 217-220), but not as long as in the next. Galls on the leaf vein, petiole, or stem; Q. lobata, Q. Douglasii.10
	Dorsal projections of the spine unusually long (fig. 221-224); head rather distinctly narrower than the thorax; galls confined to the leaf veins; Q. garryana, Q. dumosa, Q. durata, and forms of these oaks.11
10.	Insect hardly distinguishable from the next (multipunctata), with never more than a very few spots in the discoidal cell; the surface of the gall very irregular with distorted ridges and blunt spines, the gall internally solid; Q. lobata; Mendocino-Lake County area of Calif.C. heldae
	Insect hardly distinguishable from the above (heldae), sometimes with numerous spots in the discoidal cell; the gall spherical, all but microscopically smooth, internally with compacted, sometimes solid masses of fibers; Q. lobata, Q. Douglasii; Great Valley of California. C. multipunctata, 10a
	10a.	Scutellum anteriorly finely rugose, wing veins not heavy, tip of radius of moderate size, cubital cell not heavily spotted, the spots not fusing, radial cell nearly unspotted; mature galls brown, nearly smooth and naked; Central Calif.; on the leaves, petioles, and young twigs; Q. lobata. var. conspicua