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Southern beech aphidsOn this page: Sensoriaphis nothofagi tasmaniae
Apterous viviparae have 4-segmented antennae. The head is without antennal tubercles. There are rather small compound eyes, bearing comparatively large well-developed ocular tubercles. Each thoracic spiracle has a distinct pattern of sculpturing round it. The first tarsal segments have 5 hairs. Some of the abdominal segments have a short finger-like prolongation on each side, each with a thick hair at the apex. The prolongations are especially well developed on tergites VI-VIII. The siphunculi comprise round openings on greatly flattened sclerotized cones on abdominal segment V. The cauda is knobbed, and the anal plate is slightly divided.
There are 5 species in the genus Sensoriaphis. Four species feed on Nothofagus in Papua New Guinea, Australia and New Zealand, and one feeds on Melaleuca in Western Australia. Sensoriaphis is closely related to Taiwanaphis, which is found on Myrtaceae in India and east and south-east Asia.
Sensoriaphis nothofagi (New Zealand beech aphid) New Zealand
Adult apterae of Sensoriaphis nothofagi are yellowish with brown markings and narrowly oval in shape. The antennae are 4-6 segmented and are 0.33-0.41 times as long as the body. The terminal process is 0.25-0.33 times the length of the base of antennal segment VI. There are more or less interrupted transverse sclerotic bands on all abdominal tergites. Marginal tubercles are present on abdominal tergites VI & VII, but not on tergites I-IV. The tubercles are small but well developed and fingerlike. There is a pair of finger-like spinal processes on tergite VIII. Tergites I-V each have 6 spinopleural hairs. The siphunculi are quite prominent, and the cauda is globular. The body length of adult Sensoriaphis nothofagi apterae is 1.1-1.5 mm.
Both images above by permission, copyright Nicholas A. Martin, Plant & Food Research.
Sensoriaphis nothofagi alatae are yellowish with a variable degree of brown marking. The antennae bear 9-12 secondary rhinaria on antennal segment III. There are more or less interrupted brown sclerotic dorsal bars on tergites II-VI and dark marginal sclerites. The cauda is strongly constricted near the middle, forming a broadly conical knob.
Sensoriaphis nothofagi is one of only three species of indigenous aphids in New Zealand to be widespread and sometimes common; the other two are Neophyllaphis totarae and Aphis healyi (Teulon et al., 2003). They are well camouflaged, feeding on young stems and leaves of Nothofagus species, generally on trees close to forest edges. Winged and wingless parthenogenetic adults have been collected from September to May. Oviparae and winged males occur from September to February. Note the life cycles of both Sensoriaphis and Neophyllaphis species appear to be structured to allow the egg stage to survive adverse summer conditions (December-February) when there is no young growth available on the host trees (Carver & Hales, 1974).
Sensoriaphis tasmaniae (Tasmanian beech aphid) Tasmania
The adult aptera of Sensoriaphis tasmaniae (see first picture below) has the head and prothorax dirty yellow and the abdomen olive-green. The antennae are 5-6 segmented. Antennal segments I & II are brown, segments III to the base of V are pale, and the rest of segments V and VI dark. The antennal terminal process is about 0.46 times the length of the base of antennal segment VI. The head & pronotum are fused, with only the front somewhat dark sclerotic. There are two pairs of rugose, finger-like marginal processes on both the mesothorax and metathorax, and one pair of marginal processes on all abdominal tergites except V (cf. Sensoriaphis nothofagi, which just has one pair of small marginal processes on abdominal segments VI & VII). Each marginal process has a capitate hair at its apex. Tergite VIII has a pair of spinal finger-like processes in addition to the marginal processes (cf. Sensoriaphis nothofagi, which just has a pair of spinal processes on tergite VIII). The siphunculi on abdominal tergite V are prominently developed cones, brown with a broad pale flange. The cauda is constricted to form a longish pear-shaped brown knob.
Images above by permission, copyright Kristi Ellingsen, all rights reserved.
Alatae of Sensoriaphis tasmaniae have the head and thorax brown; the abdomen green and the legs brown. Antennal segment III bears 9-16 secondary rhinaria. There is a dusky, spinulose or rugose area present dorso-marginally on all abdominal tergites except segment V, each bearing 2-4 hairs. Marginal processes are variously developed, but not so well as in apterous viviparous female; these processes are most strongly developed on abdominal tergites III and IV. Spinal processes on tergite VIII are conical to finger-like, each bearing 1, rarely 2, setae. The knob of the cauda is turnip-shaped, about 2 times its maximum width at base.
The Tasmanian beech aphid infests the young shoots of myrtle beech (Nothofagus cunninghamii). Carver & Martyn (1962) report that the population was at a low level during winter, but numbers increased markedly with the advent of spring; the species was still fairly common in early December, but by February none could be found. The aphids pictured above were found in late December. Sensoriaphis tasmaniae is only found in Tasmania.