Pachypappella lactea (Tullgren, 1909)

Albrecht, Anders Christian, 2015, Identification guide to Nordic aphids associated with mosses, horsetails and ferns (Bryophyta, Equisetophyta, Polypodiophyta) (Insecta, Hemiptera, Aphidoidea), European Journal of Taxonomy 145, pp. 1-55 : 22-24

Pachypappella lactea (Tullgren, 1909)

Fig. 18 , 19D

Diagnosis

Apterae ovoid, robustly built, 0.6–1 mm, whitish, with a thin wax-dusting and exuding wax tufts from spinal and pleural wax gland plates on abdominal segments 3–6 (4 longitudinal rows of plates); marginal wax gland plates absent. Legs, antennae and rostrum short and stout. Antennae 4–5-segmented. Hind femur not distinctly thickened. RIV+V with a rather narrow and indistinct pale subapical zone. Tarsal segments fused (the segment border depicted in fig. 66b by Blackman & Eastop (1994, 2014) looks anomalous, and may be an artefact).

Dioecious, alternating between leaf galls on aspen Populus tremula (Salicaceae) and Norway spruce Picea abies (Pinaceae) , where the aphids live on thin roots within and above the mor layer (a compacted

humus layer beneath the moss layer), among moss or litter. The apterae reside in nests of dense wax wool, 1.5–2 mm across, usually one aphid in each. The nests often occur in small groups, often within the looser, wider and less distinctly delimited wax exudate of Prociphilus xylostei (deGeer, 1773) and Pachypappa species. P. lactea has a continuous anholocyclic population on spruce roots. Not associated with ants. Danielsson (1990a, 1990b) gives keys and descriptions of the root-feeding generations of Pachypappella , Gootiella and Pachypappa . See also Carter & Danielsson (1991).

Distribution

F N S.

Figures

Fig. 18. Pachypappella lactea (Tullgren, 1909). A–E. Apt. and wax cells on terminal Picea abies roots. F–G . Apt. from Hylocomium splendens sample. Two wax gland plates in F indicated by arrows.

Fig. 19. Gootiella, Pachypappa and Pachypappella. Apt. alienicolae (born on secondary host). A–B. Spinal wax gland on abd. terg. 6 of Pachypappa populi (Linnaeus, 1758) (A) and P. vesicalis Koch, 1856 (B). C. Hind leg of Gootiella tremulae Tullgren, 1925. D–G. Hind tibia and tarsus of Pachypapella lactea (Tullgren, 1909) (D), Pachypappa tremulae Tullgren, 1925 (E), P. populi (Linnaeus, 1758) (F) and P. vesicalis Koch, 1856 (G). A–B and D–G after Carter & Danielsson 1991, C after Danielsson 1990b. All modified.