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Cerataphis aphidsOn this page: Genus Cerataphis brasiliensis orchidearum
Adult apterae of Cerataphis aphids living in galls on the primary host (Styrax) have a thick covering of wax. The body is oval, 1.2-1.5 times as long as wide. The head is without horns, but has 4-7 spines ventrally. Antennae are 5-segmented, 0.22-0.25 times as long as the body, and eyes are triommatidia. The prothorax is fused with the head. The mesothorax and abdominal segments anterior to siphunculi have linear s-shaped wax gland structures. Siphunculi are present and the cauda is broadly rounded, without constriction. Immatures come in two forms: type I are normal larvae developing into adult apterae; type II are soldiers which defend the gall. Emigrant alatae have the head without horns. Antennae are 5-segmented with annular secondary rhinaria on segments III-V. The media vein of the forewing is once-branched. Siphunculi are on segment V, with 3-5 hairs, and the cauda is almost semicircular, without constriction, and with 10-16 hairs.
Apterae on the secondary host (the form most commonly observed) are dull or shiny brown, oval in shape with a transverse furrow in the middle, and a flat horizontal white fringe along the border of the body. The dorsum is wholly brown sclerotic with crenulated (=with rounded notches) margins, interrupted by the transverse furrow and free tergite VIII. Marginal rows of wax glands pass from the metathorax, ventrally to the eyes, and dorsally to the antennal bases. Ventral to the frontal wax glands are two horns, smooth, acute without hairs. Antennae have 4 or 5 segments, and are 0.16-0.26 times body length. The eyes are triommatidia. Abdominal tergites I-VII are fused, with on each side at least 30 wax glands. Siphunculi are situated dorsally, without a distinct border. The cauda is transversely elongate, with a constriction and 4-15 hairs.
There are eight species of Cerataphis (the name means aphid with horns), all originating in south-east Asia. In Asia three species host-alternate between galls on Styrax and secondary hosts in the Araceae, Orchidaceae, Palmaceae, Pandanaceae and bamboo family. Several species such as Cerataphis brasiliensis and Cerataphis orchidearum have a near cosmopolitan distribution, a result of the plant trade in palms and orchids. Most species have yeast-like extracellular symbionts, like those found in Tuberaphis.
Cerataphis brasiliensis (Palm aphid) South-east Asia; on palms in tropics & subtropics (greenhouses in temperate climates)
The gall of Cerataphis brasiliensis on its primary host, Styrax benzoin (see first picture below) is bag-like, greyish- or brownish-green, 1.0-4.7 cm long, with a single cavity and an apical slit-shaped opening. The gall arises on a stem, either from a terminal or an axillary bud. Apterae (not pictured) in the galls are orange-yellow with dark red eyes, and are covered with a thick layer of wax. The body is oval with a distinct border between the pronotum and mesonotum. They have spine-like frontal hairs on the head, including one pair of particularly sturdy hairs. The antennae are short and 5-segmented. The apical rostral segment is 0.86-0.95 times as long as the second hind tarsal segment. The abdomen is membranous with linear S-shaped wax glands. The siphuncular pores are set on small cones with a ring of 3-5 hairs. The body length of adult Cerataphis brasiliensis apterae is about 1.3 mm. Second instar sterile soldier larvae move in and around the galls. Cerataphis brasiliensis alatae emerging from the galls have 15-23 secondary rhinaria on antennal segment III, 2-8 on segment IV, and 0-4 on segment V. The body length of these alatae is 1.2-1.6 mm. They migrate to found colonies on palms.
Image above by permission, copyright Sunil Joshi & Poorani, J. Aphids of Karnataka (accessed 12/2/20).
Adult Cerataphis brasiliensis apterae on palms (see second picture above) appear sedentary, but are mobile, especially if the host plant deteriorates (Aoki, pers. comm.). They are dark brown flattened, almost circular, fringed with white wax, and often have one or more very narrow transverse white stripes across the middle region. The antennae are about 0.18 times the body length, with a terminal process 0.4 times as long as base of that segment. The front of the head is with or without cephalic horns; when present these horns are usually triangular with the apices pointed (cf. Cerataphis formosana on palms, which has the horns finger-shaped with rounded apices). Two forms of the aptera have been recognised - one with horns 45-110 μ long, and the other either lacking horns or with horns up to 18 μ long (further differences are given by Noordam, 1991). In addition there are always one, two or three pairs of short dagger-shaped spines with strongly tuberculate bases on the underside of the head next to the antennae (cf. Cerataphis lataniae, which does not have dagger-shaped spines with strongly tuberculate bases, but instead has three pairs of elongate, slender hairs with flat or slightly raised bases next to the antennae). There are wax glands around the body margin, except at the cephalic horns. The legs are short and hidden under the body. Their siphunculi are pore-like, rather near the body margin, and each have 2-4 hairs. The cauda is rounded. Immatures (see third picture above) have a light green to olive body colour, with a very short waxy fringe. Abdominal segments of the nymphs are evident, and a mid-dorsal ridge occurs on the head and thorax.
Cerataphis brasiliensis is native to South-east Asia where it galls its primary host, gum benjamin (kemenyan, Styrax benzoin). Emigrant alatae then colonise the secondary host, palms of various species especially coconut palms (Cocos nucifera) and fan palms (e.g. Livistona chinensis) and sometimes oil palm (Elaeis guineensis). Immatures can often be seen walking around the plant, but adults are mainly sedentary. Populations on palms are often attended by ants. Outside South-east Asia anholocyclic populations on palms are common in the tropics and subtropics and also in greenhouses in temperate climates. Cerataphis brasiliensis was disseminated worldwide by the international commerce of living palm plants which began in the early 20th century.
Cerataphis orchidearum (Fringed orchid aphid) On orchids in tropics & subtropics (greenhouses in temperate climates)
Adult apterae of Cerataphis orchidearum (see two pictures below) are blackish or dark reddish brown, surrounded by a fringe of wax tendrils, and with the dorsum dusted with powdered wax. Antennae are fuscous, darkening gradually towards the apices, and legs are dusky with dark tarsi. The body is flat and circular with crenulated margins. The frons has two pointed processes or 'horns', shorter than second hind tarsal segment, and also filamentous frontal setae (cf. Cerataphis brasiliensis on palms, which has 2 thick, short, lance-shaped, frontal setae). The antennae are about 0.15 times as long as the body, and are 4- or 5-segmented. The rostrum reaches to the middle coxae. The apical rostral segment (RIV+V) is almost equal in length to the second hind tarsal segment (HTII) (cf. Cerataphis lataniae on coconut palms, which has RIV+V 0.67-0.75 times HTII). There are rather long, fine hairs on the head and body and around the siphuncular pores. The longest hairs are on tergite VIII, the cauda and the anal plate. These hairs are 0.6-0.8 times as long as the width of the siphuncular pores. The legs are very short, but the tarsi are not reduced. The siphuncular pores are distinct, placed on low cones. The cauda bears 10-16 hairs. The body length of adult Cerataphis orchidearum apterae is 1.0-1.7 mm. Immature Cerataphis orchidearum (second picture below) are pale green with darker green markings, and look rather more 'aphid-like' than their adults, though still with a fringe of wax.
First two images above copyright Sharon Reid, all rights reserved;
The alate (not pictured) has a yellowish abdomen. The frons lacks 'horns', and the antennae are about 0.4 times the body length. Antennal segment III is at most 1.25 times longer than segments IV and V combined. There are about 20-30 ringlike secondary rhinaria on antennal segment III, and 8-15 each on segments IV & V. The cauda has 10 hairs (rarely less). Siphuncular pores are present. The body is 1.6-2.3 mm long.
Cerataphis orchidearum is found on various types of orchids (Orchidaceae). Earlier records of Cerataphis lataniae from orchids are thought to refer to this species. It inhabits the leaves, and sometimes the flowers of various orchids. The sexual phase is not known in this aphid, and all populations appear to anholocyclic. Alates are very scarce. The fringed orchid aphid is widely distributed in the tropics, and in glasshouses in temperate climates.