Pemphigus juncti-sensoriatus n. sp.

Host, Populus deltoides.

The Gall. A more or less globular gall located at the base of the leaf composed of leaf blade and petiole. That part consisting of leaf blade is somewhat oval, very much thickened, and more or less convex. The leaf margins can be traced along the edges of this thickened portion for some distance. The greater part of the gall is composed of a very much widened, thickened and twisted portion of the petiole. The opening is long, passing more than half way around the gall. The mouth is loosely closed and lacks the small, round orifice found in the galls of Pemphigus populi-caulis.

Taxonomy.-This species is close to populi-caulis but differs from it in having the greater part of the gall composed of petiole instead of leaf blade as in the latter and in having many of the secondary antennal sensoria of the fundatrigenia coalescent.

Pemphigus junctisensoriatus Maxson

Gall. Pale yellowish green. Composed mostly of swollen petiole; twisted on broadened leaf base; exit hole consisting of a crevice extending over halfway around between petiole and leaf.

Collections. On Populus sargenti in petiole and leaf galls. Colorado: Wiggins and Boulder. Fundatrices and alate viviparae (fundatrigeniae) June 8 and 29, alate viviparae and sexuparae Sept. 2; rare This species is peculiar in the broad and occasionally anastomosed sensoria as well as the gall which consists mostly of enlarged petiole with exit hole in the form of a long slit between petiole and leaf.

Pemphigus tartareus Hottes & Frison

(= Pemphigus junctisensoriatus Maxson)

Described originally from alate sexuparae collected on roots of Bidens sp. in Illinois, USA. Galls on Populus deltoides are pale yellowish green, composed mostly of swollen leaf petiole around broadened base of leaf lamina, with an exit hole in the form of a long slit between the petiole and the leaf (Maxson 1934). The fundatrix is pale yellowish white, with brownish head and tibiae. Alatae (BL 1.4-1.8 mm) emerge in June-July and migrate to Bidens sp(p). Smith (1985) established the synonymy with P. junctisensoriatus and made successful host transfers from Populus to Dichondra repens (Convolvulaceae) as well as to Bidens. In USA and eastern Canada.

Pemphigus junctisensoriatus Maxson, 1934

Galls resemble those of P populicaulis (see section 8), being more or less globular and incorporating tissues at the base of the leaf blade and the petiole. However, galls of P junctisensoriatus are primarily composed of petiole and have a long slit extending more than halfway around the gall. Galls of P. populicaulis are primarily composed of leaf blade tissues and have a small round opening (Maxson 1934). Palmer (1952) reported the species to be "rare." Alleyne and Morrison (1977) reported collections of P. junctisensoriatus from only one tree at Macdonald College Campus in Quebec. There have been no reports of this aphid from the grassland region, but its occurrence seems probable.

The primary host is P deltoides (Maxson 1934; Palmer 1952; Alleyne and Morrison 1977). Secondary hosts have not been reported.

Pemphigus junctisensoriatus Maxson

Galls on Populus deltoides formed at junction of leaf blade and petiole by twisting and swelling almost spherical on upper surface, largely formed from petiole, with angular slit-like opening

Galls of this aphid were also collected from cottonwood, and resemble P. populicaulis in their location and method of development. The upper gall surface is almost spherical and is formed primarily of petiole tissue (Fig. 11). Migrant escape is by means of a slit along the seams on the lower gall surface. This aphid species was reported from galls by MacNay (1955) in Canadian Insect Pest Review, but Maxson has subsequently checked the material and identified the aphid present as P. nortonii Maxson (Harper 1959). Galls of P. junctisensoriatus were all collected from a single medium-sized cottonwood at Macdonald College Campus, Quebec. No alternate hosts are known.

PEMPHIGUS TARTAREUS new species

[Described from sexupara collected from roots of Bidens sp.]