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Indomegoura aphidsOn this page: Indomegoura indica
Indomegoura are quite large aphids, with dark swollen siphunculi, living on bladdernut (Staphylea) & daylilies (Hemerocallis) in East Asia. Hille Ris Lambers (1958) established the genus Indomegoura, for the previously-named Rhopalosiphum indicum van der Goot, 1916. The new genus was characterised as having very thick slightly swollen siphunculi, only about 5 times as long as their smallest width on basal half, with the maximum swelling near the middle of their length, and reticulated at apices. Their first tarsal segments joints have 3 hairs. Tao (1963) set up another genus, Omeiomegoura, based on Omeimegoura nigrotibiae. It was similar to Indomegoura, but distinguished by the absence of the secondary rhinaria on the 3rd antennal segment, and by the shortly conical cauda in the apterous viviparous female. However, Miyazaki (1971), found that antennal segment III of O. nigrotibiae sometimes does bear a rhinarium, and suggested Omeimegoura ought to be a synonym of Indomegoura. Zhang & Qiao (1987) supported that position. Genus Delphiniobium is somewhat similar to Indomegoura, but has spiracular sclerites of thorax strongly produced, with opening very large and round, and the siphunculi slender, paler than cauda basally. Indomegoura has the spiracular sclerites of the thorax not strongly produced, with an opening of normal size, and siphunculi stout, barrel-shaped and wholly black like the cauda.
Four species in the Indomegoura genus have been described from East Asia, although in two of these the host plant is unknown, so their identity is somewhat in doubt. For the two species for which the host is known, the primary host plants of this genus are Staphylea (= Euscaphis) in Staphyleaceae. Staphylea are disconnectedly distributed in subtropical and tropical regions of North America, Europe, West Asia and East Asia, but the highest species diversity (four species) is in China. Known secondary hosts of Indomegoura species are Hemerocallis spp., but host alternation may only be partial (some remain on the primary host).
Indomegoura indica (Waxy orange aphid) South Asia, East Asia
Adult apterae of Indomegoura indica (see pictures below) are orange yellow, but they are covered in white wax which obscures the colour. The eyes and antennae are black, the legs are brownish black, apart from yellowish femoral bases. The siphunculi are dark and the cauda light reddish-brown (cf. Myzus hemerocallis on Hemerocallis, which has antennae, legs and siphunculi mainly pale). The antennae are nearly as long as the body, with a few short hairs. Antennal segment III bears at its base 5 small circular secondary rhinaria. The antennal tubercles are fairly large, distinctly protruding and rounded on the inner side. The rostrum reaches to the second pair of coxae. The apical rostral segment (RIV+V) is 0.7-0.9 times the second hind tarsal segment (HTII) (cf. Indomegoura nigrotibiae on Staphylea, which has RIV+V 0.9-1.1 times HTII). The dorsum has only a few very short hairs. The siphunculi are relatively short, considerably constricted near the tip, and with a fine reticulation only at the extreme top-end; they are only slightly swollen (cf. Rhopalosiphoninus staphyleae on Staphylea, which has its siphunculi markedly swollen on the distal 0.7). The cauda is elongate, much longer than wide, and more than 0.5 times as long as the siphunculi (cf. Indomegoura nigrotibiae, which has the cauda triangular, less than 0.5 times as long as the siphunculi). The body length of adult Indomegoura indica apterae is 3.1-4.2 mm.
First image above copyright Huang Wen, second image copyright CBG group,
Alate viviparae of Indomegoura indica have the body orange, with much less wax than the aptera. Their antennae are mainly black, but with segments I, II and base of III dusky-yellow. The secondary rhinaria on segment III are circular, of various sizes, scattered along the full length, and varying in number from 50 to 70. The rostrum reaches to the second coxae. The veins of the front wings are narrowly bordered with dusky brown. The siphunculi are black, somewhat swollen near the middle and narrow at both ends, the apical end being smallest and reticulate for a short distance. The cauda is dusky orange.
The primary hosts of Indomegoura indica in Japan are Japanese bladdernut (Staphylea bumalda) and Korean sweetheart tree (Euscaphis japonica). It is recorded as common in the Tokyo area, feeding on the undersides of the branches, which may be severely affected. In summer this aphid host alternates to its secondary hosts, daylilies (Hemerocallis spp.), although observations by Takahashi (1923) on finding apterous sexuales, and apterous and alate males on the primary host, indicate that only part of the population migrates. The waxed orange aphid was first described in India, but it now known to have a wider distribution including Japan, Korea, China, and Taiwan.