Phylloxera caryaemagna

Hosts: Carya cordiformis, tomentosa, pallida

Phylloxera caryaemagna is now considered a separate species rather than a variety of P. caryaecaulis due to its placement in a separate clade.

[Phylloxera caryaemagna has previously been considered a synonym of Phylloxera caryaecaulis, and the two are very similar in appearance. Dr Hamilton notes in couplets 12 and 13 of her first key (page 115 of the pdf), that P caryaemagna is pubescent and spongy, while caryaecaulis has hard walls and a glabrous exterior.]

Globular and light green or yellowish-white, some with a hint of crimson, spongy with short pubescence, diameter 4.0–20.0 mm; occurs along midvein of leaf with gall tissue appearing to protrude through leaf tissue above and below much more convex with a slit-like opening when mature; also occurs on petioles.

Leaf and stem gall: globular [shape]

Range: AL, AR, DE, FL, NC, OK, SC, TN, VA, WV

Dactylosphaera caryae-magnum, n. sp.?
Gall No. 6

?Pemphigus caryae-caulis [this synonymy is not valid]

Hosts: Carya amara [cordiformis]

Subglobular galls, varying in size from a quarter of an inch to one inch in diameter, the average being about half an inch, situate on leaf or its stems or mid-ribs; color greenish-white, sometimes with a blush of red on one side. The opening is beneath, in the shape of a small, elongate slit, which at length cracks open, like a chestnut burr, in three or four long slits running up the sides; after this the gall soon turns black and dries away. The cavity within is capacious, the walls being about 1/8 in thickness.

On June 17th I observed thousands of those galls and took home a large botanical box full for study. They were so numerous as to injure the growth of the trees. Those galls that had not yet began to open, and within which no parasites had gained access, were so thickly studded with young lice, that their abdomens pointed directly inward towards the centre, resembling the crystals in a geode, being wedged in as densely as mosaic work, while the whole central cavity was crowded with winged imagos; the former held on with great tenacity, while the latter were easily shaken out. In one gall I counted as many as one thousand inhabitants. At this time (June 17th) many of the galls had cracked open and the winged imagos were escaping in immense numbers. No eggs were found. The larvae were pale greenish-yellow. On June 25th the galls were all dry, black and deserted.

Phylloxera caryaecaulis (Fitch)

Shimer (1869) described three other closely-related phylloxerid species producing somewhat different twig or petiole galls on other species of Carya, which may or may not be synonymous with P. caryaecaulis: P. caryaemagna, producing velvety galls on petioles or at base of mid-rib on C. amara (= cordiformis) in Illinois and Missouri

Phylloxera caryaecaulis Fitch.

Pemphigus caryacaulis Fitch.
Dactylosphcera caryae-magnum Shimer.
Dactylosphcera spinosum Shimer.

Up to the present time these three forms of galls have been considered as quite distinct species on account of their dissimilarity, two of them being smooth and the other more or less profusely covered with fleshy spines. But a careful study of the architects of these forms forces the conclusion that they are identical, there being no tangible characters by which to separate them. The spiny form of gall always grows upon trees with pubescent leaves, such as Hicoria tomentosa, while the smooth forms are always found upon trees with smooth leaves, such as Hicoria glabra, amara and probably other species.

Ph. c.-magna Shimer may also be considered as a variety of caryaecaulis. The form is found in Missouri growing on the petioles and bases of the leaflets of Hicoria amara. Some of the specimens also closely resemble those of subelliptica Shimer, which probably belongs to it, but of which I have not yet succeeded in obtaining the migratory form. On account of some slight differences in the gall, which are no doubt due to the specific differences of the infested trees, c.-magna may perhaps be allowed to remain under a variety name, though the architects in their different stages, as far as examined, show no differences by which to separate them from the typical caryaecaulis. The galls of this variety vary from 4-20 mm in size, the normal being about 10 mm. They occur on the under side of the petiole and the base and often the midrib of the leaves, and, when in the latter position, they generally project somewhat on the upper side. The shape varies from globular to sub-conical, or broadly ovoid. The surface is quite densely covered with a minute pubescence which gives it a slightly velvety appearance. The orifice beneath is rather small and transverse and tightly drawn together before maturity. Color greenish-white to yellowish-green beneath and beautifully crimson on the upper side. Usually single, though occasionally two or more may become confluent, with their cells, however, well separated.