Raychaudhuriaphis capitata Pramanick, Samanta & Raychaudhuri Apterae are pale, colour unrecorded; BL c.1.2 mm. Alatae unknown. On Rosa involucrata (= clinophylla) in India (Manipur).

Rectinasus Theobald

Eriosomatinae: Fordini

Probably only one species, with distinctive antennal sensoriation in alatae, and the apterae on secondary hosts have a long hairy R IV+V. Affinities with other genera of Fordini were discussed by Remaudière & Davatchi (1956). A histological study of the galls (Álvarez et al. 2014) groups it with Geoica and Baizongia.

Rectinasus buxtoni Theobald Galls on Pistacia spp. (palaestina, khinjuk) are spindle-shaped sacs, 3-5 cm long and red in colour when mature, at or near the base of the main vein of a leaflet (fig. 126M). Alatae (BL 2.9-2.5 mm, fig. 81C) are produced in the third generation and leave the gall in September through small longitudinal slits in the basal half. They start colonies on roots of Compositae (Artemisia, Centaurea, Chondrilla, Helichrysum, Scorzonera, Silybum, Xanthium) and secondary host populations are also recorded from Orobanche, Citrus, Gossypium and Papaver (Zumreoglu & Akbulut, 1984) and Poaceae (BMNH collection). Apterae on secondary hosts are pale yellow; BL 2.2-3.3 mm (Plate 2e, Fig.31a,b). Alate sexuparae produced on secondary hosts have secondary rhinaria distributed III c.60, IV 5-6. Roberti (1939) redescribed the apterous exules and sexuparae, which have a very long R IV+V bearing numerous hairs. Heteroecious holocyclic in southwest Asia (Israel, Lebanon, Iran, Turkey), and populations on secondary hosts are recorded from southern Europe (Italy, Serbia, Spain), North Africa (Algeria), Kazakhstan, northern Caucasus, Transcaucasia, Dagestan and Turkmenistan. Tizado Morales & Nieto Nafría (1993) provided further information on secondary host populations. 2n = 26.

Reticulaphis Takahashi

Hormaphidinae: Nipponaphidini

About 10 east Asian species having aleyrodiform apterae with heavily sclerotized and reticulate dorsal cuticle. On Ficus or Fagaceae. At least one species forms galls on Distylium, but the taxonomy and life cycle needs further investigation, and most species are probably anholocyclic on Ficus where primary hosts are scarce or uavailable. Alatae are only known for two species. Yeh et al. (2008) reviewed the genus based largely on specimens collected on various Ficus spp. in Taiwan, and gave full species status to some of the forms previously regarded as subspecies of R distylii (asymmetrica, fici, foveolatae, rotifera). Qiao et al. (2018) reviewed and keyed the species in China.

Reticulaphis asymmetrica Hille Ris Lambers & Takahashi Apterae are elliptical, 1.5-2.0 times as long as wide, with irregular outline due to expansion of pleural regions of prosoma; black with purplish-blue burnish, without wax powder on body margin; BL 0.46-0.57 mm. On undersides of leaves of Ficus septica in in hilly areas of Taiwan, sometimes at high population densities, and on an undetermined Ficus sp. in Java (Yeh et al. 2008). The life cycle is unknown.

Reticulaphis distylii (van der Goot) Galls on Distylium stellare in Java are conical or fingertip-like, brownish-green when mature (Hille Ris Lambers & Takahashi, 1959). The gall illustrated (as Schizoneuraphis distylii van der Goot) by Docters van Leeuwen-Reijnvaan & Docters van Leeuwen (1926) seems to be another species (see Noordam, 1991, p. 259). Alatae (BL 1.4-1.9mm), with ratio of ANT III-V to head width 1.37-1.67 (cf. R. mirabilis) and secondary rhinaria distributed III 19-31, IV 7-12, V 4-10, abdomen dark green) are present in the galls in October. Host alternation apparently occurs to Ficus spp. (Hille Ris Lambers & Takahashi, 1959), but this still needs to be confirmed experimentally. Apterae regarded as R. distylii on Ficus are broadly oval to almost circular, 1.1-1.3 times longer than wide, dark brown to purplish-black, acquiring with age a fringe of wax; BL 0.6-0.8 mm. Immature apterae are yellow-brown and active. Immature alatae on Ficus have a woolly wax fringe plus long erect wax filaments; when adult they are dark violet-black, without wax. R. distylii is probably widely distributed in east and south-east Asia, and has been introduced on oriental fig trees into southern Europe (Coeur d’acier et al. 2010) and Australia (Brumley 2020). Its detailed distribution and the range of Ficus spp. used as secondary hosts still needs to be established due to confusion in the literature with R . fici. Yeh et al. (2008) recorded it from F. microcarpa, F. altissima and F. elastica in Taiwan. Zimmerman (1948) provided a well-illustrated account of an aphid under this name in Hawaii.

Reticulaphis fici (Takahashi) Apterae are broadly oval, about 1.25-1.4 times longer than wide, purplish black and becoming fully surrounded by an extensive fringe of wax; BL 0.8-0.9 mm. On undersides of leaves of Ficus spp. (including superba, elastica) in east and south-east Asia (China, Taiwan, Japan, Java, Philippines). The life cycle is unknown, but presumably many populations are anholocyclic.

Reticulaphis foveolatae (Takahashi) Apterae are elliptical, about 1.8 times longer than wide, black with purplish-blue burnish, with thick, strongly curved pale yellow marginal hairs but no marginal wax; BL only 0.4-0.6 mm. On undersides of leaves of Ficus foveolata (= sarmentosa) in Japan, on F. sarmentosa and Ficus sp. in Taiwan, and on F. benjamina in Java (Yeh et al. 2008). Other morphs and life cycle are unknown.

Reticulaphis inflata Yeh & Hsu Apterae are oval to elliptical, about 1.5 times longer than wide, black with purplish-blue burnish, with some marginal wax; BL 0.5-0.7 mm. On undersides of leaves of Ficus microcarpa in China (Hong Kong, Yunnan) and Taiwan (Yeh et al. 2008), and introduced to Western Australia (first record 1997, on F. benjamina; Brumley 2020). Other morphs and life cycle unknown.

Reticulaphis mirabilis (Takahashi) Apterae are oval, black with purplish-blue burnish, about 1.4 times longer than wide, strongly sclerotized, without marginal wax; BL 0.5-0.7 mm. Attached firmly to undersides of leaves of Ficus irisana (= ampelas), F. ?virgata and Ficus sp. in Taiwan (Takahashi, 1939a; Yeh & Hsu 2008), and also recorded from Thailand (Tao, 1966). Alatae have BL 1.1-1.3 mm, with ratio of ANT III-V to head width 1.02-1.14 (cf. R. distylii), and secondary rhinaria distributed ANT III 15-19, IV 4-5, V 2-4. The life cycle is unknown.

Reticulaphis rotifera Hille Ris Lambers & Takahashi Apterae are broadly oval, about 1.25 times longer than wide, black with purplish-blue burnish, with marginal wax (see aphids of Karnataka website – although the identity of this Indian population needs to be confirmed); BL 0.5-0.6 mm. On undersides of leaves of Ficus virgata in Taiwan, and also recorded from F. ?pruniformis = ? depressa) in Java, and from F. religiosa in southern India. Other morphs and life cycle are unknown. [Aphids collected from Quercus sp. in India, identified as R. distylii rotifera (Raychaudhuri et al., 1980c; A.K. Ghosh 1988) are evidently a different, probably undescribed, species.]

Reticulaphis septica Yeh & Hsu Apterae are very small, oval, 1.3-1.4 times as long as wide, black with purplish-blue burnish, without marginal wax; BL c. 0.5 mm. On undersides of leaves of Ficus septica, sometimes reaching high densities on mature leaves, in Taiwan (Yeh et al. 2008). Other morphs and life cycle are unknown.

Reticulaphis shiiae Takahashi Apterae are oval, black, with black legs; BL 0.7-0.9 mm. On leaves of Castanopsis cuspidata in Japan (Takahashi, 1958a). Aphids from an unidentified host in India were also identified as this species (A.K. Ghosh 1988). Other morphs and life cycle are unknown.

Reticulaphis similis Hille Ris Lambers & Takahashi Described as a subspecies of R distylii based on one sample on the underside of a mature leaf of Ficus benjamina in Java. Regarded by Yeh et al. (2008) as incertae sedis because of the poor quality of the available specimens.

Rhinariaphis Kanturski & Stekolshchikov

Aphidinae: Macrosiphini

One species in Central Asia (Afghanistan) with affinities to Eucarazzia and Klimazewskia, but with a different combination of characters (see Kanturski & Stekolshchikov 2018).

Rhinariaphis tuberculata Kanturski & Stekolshchikov Colour of apterae in life unknown; BL 1.9-2.8 mm. On Lophanthus pinetorum ( = Nepeta cabulica) in Afghanistan (Kanturski & Stekolshchikov 2018). Other morphs and biology are unknown.

Rhodobium Hille Ris Lambers

Aphidinae: Macrosiphini

One species differing from Acyrthosiphon and Metopolophium in its scabrous antennal tubercles, and from Aulacorthum in having secondary rhinaria along the whole length of ANT III and lack of dorsal pigmentation in alatae. An account was given by Heie (1994).

Rhodobium porosum (Sanderson) Plate 24b Apterae are yellow to yellow-green, rather shiny, with brown head; BL 1.2-2.5 mm. Alatae have a bright green abdomen with no dorsal markings. On Rosa spp., esp. cultivated varieties, and Fragaria spp. Perhaps North American in origin, now widely distributed. Monoecious holocyclic in North America, with oviparae and alate males occurring on both Rosa and Fragaria (MacGillivray 1963a), but the yellow form on Fragaria in North America is possibly a distinct species. R. porosum is also holocyclic on Rosa in parts of Europe (Müller & Steiner 1988b), but generally anholocyclic on cultivated roses in glasshouses, or outside in warmer climates. 2n=14.

Rhododendraphis Barjadze & Özdemir

Aphidinae: Macrosiphini

One Rhododendron-feeding species with a sclerotic dorsum, a long rostrum with hairy R IV+V, spinulose tarsi, and siphunculi with distal swelling. Barjadze & Özdemir (2014) provided a key distinguishing apterae from those of other Rhododendron-feeding aphids with spinulose tarsi.

Rhododendraphis tuatayae Barjadze & Özdemir Colour of apterae in life is unknown, probably brown or black; BL 1.4-1.7 mm. Apterae have 3-8 secondary rhinaria on distal part of ANT III, alatae are unknown. On an unidentified species of Rhododendron in north-eastern Turkey. Other morphs and life cycle are unknown..

Rhopalomyzus Mordvilko

Aphidinae: Macrosiphini

Nine species with clavate siphunculi, small but evident antennal tubercles, and alatae with secondary rhinaria on both ANT III and IV. Apterae are similar to those of Myzus, Neotoxoptera, and Dysaphis (Pomaphis). Those with known life cycles mostly alternate between Lonicera and Poaceae in the temperate northern hemisphere. Accounts are available for Europe (Hille Ris Lambers 1953, Heinze 1960, Heie 1994, Blackman 2010), Central Asia (Narzikulov & Umarov 1969), and North America (Palmer 1952, in Rhopalosiphum).

Rhopalomyzus alaica Mukhamediev & Akhmedov Apterae (fundatrices) are dark brown with brown cauda and paler siphunculi; BL 2.2-2.7 mm. On Lonicera microphylla in Central Asia. The second generation are apparently all alate, migrating to an unknown secondary host. Oviparae and alate males occur in late September-October (Mukhamediev & Akhmedov 1982).

Rhopalomyzus codonopsidis Umarov Apterae are very pale, translucent white; BL c.1.6-1.8mm. Alatae have numerous secondary rhinaria distributed III c.60-64, IV 28-30, V 13-14. On Codonopsis clematidea in Tajikistan and Kazakhstan, and also recorded from this host in Pakistan (Naumann-Etienne & Remaudière 1995). Heteroecious holocyclic with a sexual phase on Lonicera; Kadyrbekov (2002e) collected oviparae and alate males on L. korolkovii in Kazakhstan in early October that he attributed to this species, and he has also reported it from L. tatarica (Kadyrbekov 2017a)..

Rhopalomyzus grabhami (Cockerell) Apterae on grasses are greenish black, slightly shiny, with dark appendages; BL 1.4-1.7 mm. At bases of stems of unidentified grasses (laboratory-reared on Poa annua; Hille Ris Lambers 1966). In western North America. Heteroecious holocyclic with sexual phase on Lonicera, where fundatrices and their alate progeny roll leaves in spring and cause bright red-yellow blotches.

Rhopalomyzus hissarica Narzikulov Apterae (fundatrices) are dark green; BL 2.0-2.2 mm. On Lonicera spp. in Central Asia. Alatae have secondary rhinaria distributed ANT III 43-46, IV 22-23, V 5-6. Mukhamediev & Akhmedov (1982) discussed its biology.

Rhopalomyzus (Judenkoa) lonicerae (Siebold) Apterae (fundatrices) are dark green with dark head, antennae, legs, siphunculi and cauda, the body powdered with greyish wax; BL 2.0-2.6 mm. On leaves of Lonicera in spring, rolling leaves towards undersides and causing yellow and red spots. Heteroecious holocyclic, migrating in second generation to grasses, esp. Phalaris arundinacea, where it is a pale yellowish aphid forming dense colonies on leaves (see influentialpoints.com/Gallery). Sexuales commonly occur in autumn on Symphoricarpos in north-west Europe (Heie 1994), although it is not known if the life cycle can be completed on that plant. In Europe, Central Asia, west and east Siberia, and North America. 2n=12.

Rhopalomyzus narzikulovi Mukhamediev & Akhmedov Apterae are matt green, lightly dusted with grey wax powder; BL 2.3-2.6 mm. In spring colonies on Lonicera bracteolaris and L. nummularifolia in Central Asia. The secondary host is possibly Bunium persicum. Gynoparae and alate males return in September (Mukhamediev & Akhmedov 1982).

Rhopalomyzus poae (Gillette) Plate 18d Apterae on grasses are reddish brown , dark brown or blackish, wax-powdered on underside, with dusky/dark appendages; BL 1.3-1.8 mm. On basal parts of grasses (Agrostis, Dactylis, Festuca, Glyceria, Phalaris, Poa), often on etiolated stems under stones. In Europe, USA, and there are also records from Kazakhstan, Pakistan, Bolivia, Peru and Argentina. Heteroecious holocyclic with sexual phase on Lonicera, all progeny of the fundatrix being alate. Anholocyclic in mild climates. Wood-Baker (1970) provided biological notes.

Rhopalomyzus smilacis (Matsumura) Apterae are (probably) dirty yellow; BL c. 3 mm. On upper parts of shoots of Smilax china and Viburnum sp. in Japan. This species has not been identified since the original description (1918), which is insufficient for it to be included in keys. Its generic position and true host plant are also uncertain.

Rhopalomyzus tianshanica Narzikulov Apterae are green. On Lonicera spp. in Central Asia. Oviparae and alate males occur in early October (Mukhamediev & Akhmedov 1982).

Rhopalosiphoninus Baker

Aphidinae: Macrosiphini

About 20 species with well‑developed antennal tubercles, large and strongly clavate siphunculi, and a short triangular cauda, living on a variety of plants but occurring particularly in cryptic habitats in the summer. Several species have host alternation, with primary hosts in several families (Caprifoliaceae, Hydrangeaceae, Staphyleaceae). Ten species are from India and the Far East, six are European, and three are known only from North America. Accounts are available for Europe (Hille Ris Lambers 1953, Heinze 1961, Heie 1994, Blackman 2010), Siberia (Pashchenko 1988a), Japan (Miyazaki 1971), India (Bhattacharya & Chakrabarti 1982), and North America (Smith & Knowlton 1977).

Rhopalosiphoninus (Pseudorhopalosiphoninus) calthae (Koch) Apterae are shining brownish black (see influentialpoints.com/Gallery); BL 2.1-3.0 mm. On undersides of leaves of Caltha palustris growing in the shade in Europe, where all the numerous collections have been from this host. However, in eastern Kazakhstan it has now been reported to occur on Aconitum leucostomum (Kadyrbekov 2009a). Monoecious holocyclic with oviparae and apterous males on C. palustris in August (Finland) to October (Netherlands, Hille Ris Lambers 1953).

Rhopalosiphoninus celtifoliae Shinji (Fig.61b,c) Colour of apterous fundatrices in life is unknown (alatae are yellowish orange with black dorsal patch); BL (of fundatrix) 3.0-3.2 mm. On Deutzia, Diervilla and Weigela in spring, migrating in second generation to an unknown secondary host (Miyazaki 1971). (It was originally described from Prunus pseudocerasus, but this is unlikely to be a host.) Only known from Japan.

Rhopalosiphoninus deutzifoliae Shinji Apterae are green, with antennae and legs pale darkened apically, and dark siphunculi and cauda; BL 2.4-2.7 mm. Spring populations occur on leaves and stems of Hydrangeaceae (Deutzia, Hydrangea, Philadelphus), and also apparently Weigela coraeensis (Caprifoliaceae; Moritsu 1983), curling the leaves, and migrating to an unknown secondary host. Alatae have a large black dorsal patch and 12-20 secondary rhinaria on ANT III only. In Japan, China and east Siberia. This is possibly the primary host form of the widely distributed anholocyclic bulb and potato pest Rh. latysiphon (q.v).

Rhopalosiphoninus ehretis Bhattacharya & Chakrabarti Colour in life is not recorded, probably apterae are pale; BL 1.9-2.1 mm. Forming spiral leaf-rolls in spring on Ehretia acuminata in Uttar Pradesh, India (Bhattacharya & Chakrabarti 1982). It is also recorded from Schisandra grandiflora (Chakrabarti & Sarkar 2001). Alatae have a brown dorsal abdominal patch. The life cycle is unknown.

Rhopalosiphoninus elsholtze Chakrabarti & Medda Colour of apterae in life is unrecorded: BL 1.5-1.8 mm. On Elsholtzia fruticosa in Uttar Pradesh, India. Alatae are undescribed, and sexual morphs and life cycle are unknown.

Rhopalosiphoninus (Submegoura) heikinheimoi (Börner) Apterae are very dark brown to almost black, slightly shiny; BL 2.0-2.8 mm. On Vicia cracca and Lotus corniculatus, at stem bases close to ground usually hidden by tall grass or leaves. In northern and central Europe. Monoecious holocyclic with oviparae and apterous males in October (Hille Ris Lambers 1953).

Rhopalosiphoninus hydrangeae (Matsumura) Apterae are pale to dull yellow, sometimes with a greenish tinge; BL c.2.3-2.4 mm. On Hydrangea spp. in Japan and east Siberia. Monoecious holocyclic, with oviparae and alate males in October (Miyazaki 1971). 2n=12.

Rhopalosiphoninus indicus L.K. Ghosh Colour in life is unrecorded, probably brown; BL 1.4-1.9 mm. On roots of Zea mays in Himachal Pradesh, India. It needs to be confirmed that this species is not synonymous with R. latysiphon.

Rhopalosiphoninus latysiphon (Davidson) Bulb‑and‑Potato Aphid Plate 21a Apterae are shiny dark olive green with very striking swollen shiny black siphuculi; BL 1.4‑2.5 mm. Alatae have shiny olive‑green to black dorsal abdominal markings. On bulbs (Tulipa, Gladiolus) and potato (Solanum tuberosum) tubers in store, and on roots of many plants, especially in clay soils (e.g. potato crops), or on etiolated stems or runners growing in darkness under stones (e.g. Bromus sterilis, Convolvulus arvensis, Potentilla anserina, Vinca major, Urtica spp.). Throughout Europe and in Egypt, Rwanda, Kenya, South Africa, India, Pakistan, Nepal, Sri Lanka, Japan, China and east Siberia (? ‑ see below), Australia, New Zealand, and North, Central and South America. Anholocyclic, overwintering on stored bulbs and potatoes in cold temperate regions; sexual morphs are not recorded. However, it is possible that Rhopalosiphoninus deutzifoliae (q.v.) on Hydrangaceae in Japan and east Siberia is the primary host form. Rh. latysiphon ssp. panaxis Zhang, described from Panax quinquefolium in China (Qiao & Zhang 1999c) appears to be a synonym. See also Blackman & Eastop (2000). 2n = 6 ( + 1).

Rhopalosiphoninus longisetosus Chakrabarti & Ghosh Apterae are unknown, alatae have BL c.2.7 mm. Described from an unidentified plant, the original description comprising an alate female, an alate male and 15 oviparae collected in December in Himachal Pradesh, India. There is a subsequent host record from Elsholtzia flava, which is possibly the secondary host, in Uttar Pradesh in October (Chakrabarti & Sarkar 2001).

Rhopalosiphoninus maianthemi Stroyan Colour of apterae is unknown, probably yellow-green with dark sclerotic parts; BL c.1.8-2.0 mm. On roots of Maianthemum bifolium in Italy, and Austria (BMNH collection, leg. R.N.B. Prior). Monoecious holocyclic, with oviparae and alate males in early September (original description).

Rhopalosiphoninus ribesinus (van der Goot) Apterae are dull reddish brown to brownish black, with black siphunculi (see influentialpoints.com/Gallery); BL 2.2-3.0 mm. Alatae have only marginal and intersegmental sclerites, and secondary rhinaria distributed III 40-60, IV 6-16, V 0-1. On old canes of Ribes rubrum, and sometimes on R. nigrum, close to the ground in rather damp and shady places, or on young shoots and leaves. In Europe and west Siberia. Monoecious holocyclic with apterous males (Hille Ris Lambers 1953).

Rhopalosiphoninus smilacifoliae (A.K. Ghosh & Raychaudhuri) Described from a single, possibly vagrant, alata collected on Smilax sp. in Sikkim, India.

Rhopalosiphoninus solani (Thomas) Apterae are dark green tinged with brown, with black siphunculi and cauda (Wilson 1915, as Amphorophora subterrans); BL 1.6-2.1 mm. Originally described from tomato, but if Amphorophora subterrans is indeed a synonym then this species feeds subterraneously on the roots of Dactylis glomerata. It is widely distributed in North America (Smith & Parron 1978).

Rhopalosiphoninus staphyleae (Koch) Plate 21b Apterae on Staphylea in spring are yellowish-white or pale yellow with a translucent whitish spot on anterior part of dorsal abdomen; BL 2.3-3.0 mm. They cause the leaves to curl and become mottled pale yellow. R. staphyleae s. str. is heteroecious holocyclic; alatae, with a large black dorsal abdominal patch, migrate from late May onwards to found colonies particularly on Liliaceae and Iridaceae (Tulipa, Hemerocallis, Crocus, Anthericum), and also sometimes on roots or etiolated parts of plants in at least eleven other families (e.g. Anemone, Capsella, Cardamine, Dentaria, Lamium, Oxalis, Vinca), as well as records from trees (e.g. Forbes & Chan 1989), and grasses (e.g. Wood-Baker 1970). Apterae on secondary hosts, and also in populations remaining through summer on Staphylea, are much more pigmented than the spring generations; dark olive green or brownish with very dark green or black dorsal markings. The holocycle is only recorded from Europe, but anholocyclic populations of staphyleae group are almost cosmopolitan (see Blackman & Eastop 2000, p. 331). In Europe - and possibly introduced to North America - there is a form usually regarded as a subspecies, Rh. staphyleae ssp. tulipaellus Theobald, the Mangold Aphid, which is particularly a pest of stored mangold beets (Beta vulgaris), but is also recorded from the roots of a wide range of other plant genera including Galium, Lycopersicon, Rumex, Tulipa and Viola. There is evidence that this form may have a sexual phase without migration to Staphylea in continental Europe (see Blackman 2010), and may justifiably be treated as a separate species, but further investigation is needed to clarify the life cycle and genetic relationships. 2n = 10.

Rhopalosiphoninus tiliae (Matsumura) Apterae on Tilia in spring are yellowish-green with brownish antennae and mainly black legs and siphunculi; BL 2.7-3.0mm. On the undersides of young leaves, which become curled (Miyazaki 1971). Heteroecious holocyclic; alatae with a large black dorsal abdominal patch migrate from early June onwards to found colonies on leaves and flower-stems of Adenocaulon himalaicum (Miyazaki 1985). In Japan, eastern Russia (Pashchenko 1984a) and north-west China (G. Zhang 1999). 2n = 12 (Shinji 1941, as nobukii).

Rhopalosiphum Koch

Aphidinae: Aphidini

About 15 species associated with Prunus or Pyroideae as primary hosts, and Poaceae, Cyperaceae, or more rarely other plants as secondary hosts. Most Rhopalosiphum and the viruses that they transmit probably originate from North America (Halbert & Voegtlin 1998), with a subsidiary centre in Asia (R. maidis and R. rufiabdominale), where the taxonomic situation has not been sufficiently investigated. Previously many other species with rather short, slightly swollen siphunculi were included in Rhopalosiphum., including genera now placed in Macrosiphini (e.g. Hyadaphis, Lipaphis, Rhopalomyzus). Rhopalosiphum is closely related to Melanaphis and Schizaphis, and the limits of these three genera are not clearly defined. Skvarla et al. (2019) used multivariate morphometrics to confirm numerous synonymies within the genus. Accounts are available for Britain (Stroyan 1972b, 1984), north-west Europe (Heie, 1986), Iberian peninsula (Nieto Nafría et al. 2005a), north-east India (Raychaudhuri 1980), east Siberia (Pashchenko 1988a), Japan (Takahashi 1965c, Torikura 1991), Australia (Eastop 1966), Canada (Richards 1960), and North America (Richards 1962).

Rhopalosiphum cerasifoliae (Fitch) (fig. 88E) Apterae in spring colonies are pale yellowish to pale green with spinal, marginal and intersegmental lines of darker green pigment and a dusting of wax; BL 2.0-2.5 mm. On leaves and shoots of Prunus virginiana and P. pennsylvanica, distorting growing tips and rolling the leaves. Heteroecious holocyclic; alatae migrate in May-June to form colonies on stems of Cyperaceae (Schoenoplectus, Scirpus, Eleocharis). Apterae on secondary hosts are apple-green; BL c.2 mm. They are also found on Juncus. Records from Carex spp. need confirmation as Voegtlin & Halbert (1990) could not obtain colonies on Carex despite extensive transfer attempts. Populations sometimes also persist on the primary host (Richards 1960). Oviparae on Prunus in autumn are yellow with siphunculi pale-dusky (cf. R. padi). Widely distributed in North America. 2n = 8.

Rhopalosiphum chusqueae Pérez Hidalgo & Villalobos Muller Apterae are brown with white spots of wax on abdomen; BL 2.2-2.7 mm. On the bamboo Chusquea tomentosa in Costa Rica, living close to the nodes and well protected by the leaves, so not easily detectable (Pérez Hidalgo et al. 2012a). Alatae and life cycle are unknown.

Rhopalosiphum dryopterae Kan We have not seen the description of this species, collected from Dryopteris filix-mas in Kirghizia (Holman 2009). It is possibly a species of Dysaphis (Holman, cited in Halbert & Voegtlin 1998).

Rhopalosiphum enigmae Hottes & Frison Apterae are dark reddish brown to greenish brown or dark green (see influentialpoints.com/Gallery); BL 1.7-2.3 mm. Alatae have secondary rhinaria distributed III 7-15, IV 0-3. On Typha spp., esp. T. latifolia, forming colonies concealed within leaf sheaths, and also recorded from Sparganium sp. Widely distributed in North America. Monoecious holocyclic with alate males (Hottes & Frison 1931). Skvarla et al (2018) synonymised R. laconae Taber with R. enigmae and reported on its biology including associated ants, parasitoids and predators. 2n=10.

Rhopalosiphum maidis (Fitch) Corn Leaf Aphid Plate 8i Apterae are rather elongate-bodied, yellow‑green to dark olive green or bluish green, sometimes dusted with wax, with short dark siphunculi (see aphids of Karnataka website and/or influentialpoints.com); BL 0.9‑2.4 mm. Alatae have secondary rhinaria distributed III 6-30, IV 0-14, V 0-5. On young leaves of grasses in more than 30 genera including Avena, Hordeum, Oryza, Saccharum, Secale, Sorghum, Triticum and Zea, and occasionally on Cyperaceae and Typhaceae. Asiatic in origin, R. maidis is now virtually cosmopolitan. It is entirely anholocyclic in most parts of the world, being unable to survive outdoors in regions with severe winter climates, although males occur sporadically, and have been collected on Prunus sargentii (= sachalinensis) in Japan (Torikura 1991). It is heteroecious holocyclic in Pakistan, with P. cornuta as primary host (Remaudière & Naumann-Etienne 1991), and it is also reported to have P. mume and P. persica as primary hosts in Korea (Lee et al. 2002c). On P. cornuta in Pakistan fundatrices and their wax-powdered apterous progeny feed along veins on undersides of deformed leaves, in mixed colonies with Myzus cornutus. Alatae migrate to Poaceae before the end of May. This is probably the most important aphid pest of cereals in tropical and warm temperate climates, and there is an extensive literature; see Blackman & Eastop (2000, p. 332-3). The genome sequence was analysed by Chen et al. (2019) and compared with that of Acyrthosiphon pisum by Y. Li et al. (2020). Csorba et al. (2021) studied biodiversity of its endosymbionts on maize.

2n = 8, 9, and 10; there is an association between karyotype and host plant, the barley-colonizing form in the northern hemisphere having 2n = 10, whereas populations on maize and sorghum have 2n = 8 (Brown & Blackman 1988, Blackman & Brown 1991).

Rhopalosiphum musae (Schouteden) Apparently heteroecious between Prunus and marsh or water plants (e.g. Scirpus) in US Rocky Mountain region from Washington to Colorado. Oviparae and alate males were described from Prunus besseyi in Colorado in October-November (Gillette and Palmer, 1932; as scirpifolii), and some sexuales collected along with gynoparae on P. subcordata in Oregon in October (BMNH collection, leg. L.G. Gentner) agree well with that description. However, the spring generations have not been described, so we are not able to include this species in the key to Prunus aphids. R. musae was originally described from a glasshouse population on Musa ensete in Belgium. Specimens from presumably anholocyclic populations on secondary hosts in Cyperaceae (Scirpus), Musaceae (Musa, Ensete) and Strelitziaceae (Strelitzia), or trapped alatae identified as this species, are recorded from England, Germany, Iran, Rhodesia, Tanzania and Australia (BMNH collection). Apterae on secondary hosts are dark brown to greenish black, sometimes with orange spots at bases of SIPH; BL 2.0-2.3 mm.

Rhopalosiphum nigrum Richards Apterae in spring colonies on Crataegus sp(p). are dark green to blue-black, usually dusted with wax; BL 1.7-2.2 mm. Heteroecious holocyclic; alatae migrate in late May-early July to grasses and sedges in damp situations (Richards 1960); identified hosts are Zizania aquatica and Alisma sp. (BMNH collection, leg. A Hsu). Apterae on secondary hosts are green with reddish blotches around the bases of the siphunculi; BL 1.3-2.2 mm. In Canada (Ontario, Manitoba), and there are unconfirmed records from USA (Oregon, Utah).

Rhopalosiphum nymphaeae (L.) Water Lily Aphid (fig. 88D) Apterae are reddish brown to dark olive, dusted with light grey wax, especially on abdominal tergites 1-4 (see influentialpoints.com/Gallery); BL 1.6‑2.9 mm. Alatae are shining brown-black with white wax dorsal markings, and have secondary rhinaria distributed III 14-24, IV 0-8, V 0. Colonies occur on a large variety of water plants (Alisma, Butomus, Callitriche, Echinodorus, Euryale, Juncus, Lemna, Nelumbo, Nuphar, Nymphaea, Potamogeton, Sagittaria, Sparganium, Spirodela, Triglochin, Typha, etc.), with some ability to survive underwater. Heteroecious holocyclic, with a sexual phase on Prunus spp. Spring colonies feed on young twigs, leaf petioles and fruit stalks of various Prunus spp. (domestica, insititia, spinosa, etc.), curling the leaves and attended by ants. Spring migrant alatae fly to secondary hosts in May-June. R. nympheae is almost cosmopolitan, and has been used for biological control of water weeds in rice (Oraze & Grigarick 1992). Genetic diversity in the eastern Baltic region and elsewhere was studied by Rakauskas et al. (2014b). Performance on different species of duckweed was investigated by Subramanian & Turcotte 2020). Bionomics and control on aquatic vegetables in India was studied by Halder et al. (2020). See also Blackman & Eastop 2000. 2n = 8 (Russia, Kuznetsova & Shaposhnikov, 1973, and Italy (Blackman & Eastop 1994) or 16 (India, Behura & Bohidar, 1978, and Kurl, 1986b); the difference warrants further investigation.

Rhopalosiphum oxyacanthae (Schrank) ( = insertum Walker) Apple-Grass Aphid Apterae in spring colonies are rather shiny, bright green to yellow-green with a dark green spinal stripe (see influentialpoints.com/Gallery); BL 2.1-2.6 mm. They curl young leaves of Pyroideae (Cotoneaster, Crataegus, Malus, Pyrus, Sorbus and sometimes Cydonia and Mespilus). It may also occasionally form colonies on suckers of Prunus spp. Heteroecious holocyclic; alate spring migrants (with secondary rhinaria distributed ANT III 12-21, IV 2-11, V 0-6) fly in late May-June to found colonies on subterranean parts of various Poaceae (Agropyron, Agrostis, Alopecurus, Dactylis, Festuca, Glyceria, Phalaris, Poa, Triticum), although colonies may persist into summer on primary hosts. Apterae on grasses in summer are yellowish green with yellowish‑brown head and pronotum and dusky to dark‑brown siphunculi, BL 1.1‑2.0 mm. They are attended by ants. In Europe, North Africa (Tunisia; Boukhris-Bouhachem et al. 2007), the Azores, south-west and central Asia, and Japan (Torikura 1991); possibly originating from North America (where for many years the name fitchii was used for this species on its primary hosts). In Australia and New Zealand on grasses and maize there are two closely-related taxa (Rhopalosiphum sp. “near insertum” and “sp. x” respectively) of unclear genetic and geographical origins (Valenzuela et al. 2009b); in New Zealand apterae of this group have been collected on apple in spring, and oviparae and gynoparae of “R. near insertum” have been found on Sorbus. Vidano (1959) published a detailed account of the life cycle of R. oxyacanthae in Italy. Evenhuis (1968) studied its natural control and the role of a parasitoid in apple orchards. Aphids resembling R. oxyacanthae and with similar host associations in Central America may be the closely-related species R. sanguinarium (q.v.). See also Blackman & Eastop 2000, p. 332, as insertum. [The name insertum (Walker) has been used widely in the literature for this species, but we now follow Garcia Prieto et al. (2004) in accepting the validity of oxyacanthae.] 2n = 10.

Rhopalosiphum padi (Linnaeus) Bird Cherry‑Oat Aphid Plate 8g, fig. 88F Apterae in spring colonies on Prunus are pale green to dark green, brown or nearly black, with a rust-red patch around base of each siphunculus, and a coating of mealy wax (see influentialpoints.com/Gallery); BL 2.0-2.9 mm. Heteroecious holocyclic; the primary host are bird-cherries, usually Prunus padus in Europe, feeding on undersides of young leaves which become longitudinally rolled or folded to enclose the aphid colony. R. padi is normally very conservative in its choice of primary host, but Kudirkaité-Akeliené & Rakauskas (2009) found fundatrices on Syringa vulgaris in Lithuania. In Japan the sexual phase occurs on P. padus, P. grayana and P. ssiori (Torikura 1991). In North America the main primary host is P. virginiana and the leaf distortion may be less (Richards 1960). Alatae (with secondary rhinaria distributed ANT III 12-33, IV 1-11, V 0-6) migrate in May-June to numerous grasses and cereals, including all the major cereals and pasture grasses, and other monocots, but colonies may also persist into summer on Prunus, and the numerous records from other Prunus spp. may be mainly the result of secondary infestations. R. padi is also sometimes found on Cyperaceae, Iridaceae (especially Iris), Juncaceae, and Typhaceae, and in England it has been found overwintering on dicots (Capsella, Stellaria). Apterae on secondary hosts are broadly oval, green mottled yellowish green or olive green, or dark olive to greenish black; often with rust‑coloured patches around the bases of siphunculi (see influentialpoints.com/Gallery); BL 1.2‑2.4 mm. Distribution is now virtually cosmopolitan, anholocyclic populations occurring in warm climates or where primary hosts are unavailable. Leather (1988) reviewed its biology on P. padus in Europe. Loxdale & Brookes (1988) and Sherlock et al. (1986) respectively studied enzyme variation and elemental composition in holocyclic populations. Tatchell & Parker (1990) studied selection of the primary host by return migrants, and Nam & Hardie (2014) compared host acceptance of primary and secondary hosts by different alate morphs. Delmotte (2001) discussed the origins of anholocycly in this species. DNA studies have shown that the commonest anholocyclic lineages in Europe were derived by hybridisation with another closely related species, as yet unknown (Delmotte et al. 2003). In recent years there has been much work in France on the co-existence and genetic interactions between different life-cycle forms of this species (e.g. Halkett et al. 2008, Carter et al. 2012, Gilabert et al. 2015). The genetic diversity of introduced anholocyclic populations has been studied in Australia by Valenzuela et al. (2010b), and by Rubio-Meléndez et al. (2019) in Chile, and that of mainly holocyclic populations in the eastern Baltic region by Rakauskas et al. (2014b). Transcriptome analysis has also been used to provide numerous polymorphic markers for further studies of the population genetics of this species (Duan et al. 2017). See Blackman & Eastop (2000, pp. 333-4, and 2007) for other key references. 2n = 8 (or sometimes 9; Hales & Cowan 1990).

Rhopalosiphum padiformis Richards Apterae are green, with large red patches around bases of siphunculi; BL 1.4-2.2 mm. Distinguished from R. padi and R. insertum by the long, pointed hairs on the posterior abdominal tergites. Described from the flower heads of Poa sp. in Canada (British Columbia), subsequently found on wheat in Montana, USA. Probably heteroecious holocyclic with sexual phase on woody Rosaceae; alate males were obtained in a culture of the Montana population (T.W. Carroll & D.Yount, pers. comm). 2n=10.

Rhopalosiphum parvae Hottes & Frison Apterae are brownish yellow, reddish brown or more rarely greenish yellow; BL 1.2-1.8 mm. Alatae have secondary rhinaria distributed III 7-11, IV 0-2. Described from Carex sp. in Illinois, USA (as “variety” of R. enigmae). A population feeding on inflorescences of Scirpus (= Schoenoplectus) lacustris in Sicily that agreed well with the original description was fully redescribed and illustrated by Barbagallo & Stroyan (1982).

Rhopalosiphum rufiabdominale (Sasaki) Rice Root Aphid Plate 8h Apterae in spring colonies on young leaves, stems and suckers of Prunus spp. (e.g. mume, salicina, yedoensis) in east Asia are reddish or greenish-brown with bluish-white mealy wax on sides of body and forming dorsal cross-bands (Moritsu 1983); BL 2.0-2.6 mm. Rhodotypos scandens may also be used as a primary host (Torikura 1991). Heteroecious holocyclic (Tanaka 1961); alatae migrate in May-June to form colonies on underground parts of numerous species of Poaceae, Cyperaceae and some dicots, particularly Solanaceae (potato, tomato, capsicums). Apterae on secondary hosts are olive green, dark green or brownish with yellowish tints, with a rusty suffusion around bases of siphunculi and on posterior dorsum (see aphids of Karnataka website and influentialpoints.com/Gallery); BL 1.2-2.8 mm. Alatae on secondary hosts normally have 5-segmented antennae with secondary rhinaria distributed III 3-35, IV 0-4. It is a major pest of rice (Yano et al. 1983; Blackman & Eastop 2000, p. 334-5). Anholocyclic populations occur throughout most of the world on secondary hosts, particularly in warmer climates and in glasshouses, where it may be a pest on plants in hydroponic cultivation, such as Cannabis. However, early spring populations have recently been found on Prunus spp. (armeniaca, domestica) in Italy (Rakauskas et al. 2015b), indicating that a holocycle may now have been established in Europe. 2n=8.

Rhopalosiphum rufulum Richards Apterae in spring colonies on Crataegus in Canada are mainly maroon, mottled with green or yellow, with a pattern of mealy wax; BL 2.0-2.5 mm (Richards 1960). Presumably in Canada it is heteroecious holocyclic; alatae (with secondary rhinaria distributed ANT III 12-23, IV 5-12, V 0-4) leave Crataegus in May-June. However, although collected from Crataegus sp(p). in spring in Manitoba, Quebec, Ontario and New Brunswick, the secondary host populations have until recently only been known from Europe (UK, Netherlands, Denmark, Germany, Poland, Czech Republic, Italy, Latvia, Lithuania), where large populations have often occurred since about 1970 on Acorus calamus (see Heie 1986). Specimens from Acorus in USA (Massachusetts, New York) and Canada in museum collections have however now been identified as this species (Skvarla et al. 2019). Alatae have also been trapped in Tunisia (Boukhris-Bouhachem et al. 2007). Apterae on Acorus are dark brown to black, with dark appendages; BL 1.4-2.4 mm. Alatae produced on Acorus have secondary rhinaria distributed III 16-25, IV 7-13, V 1-4. Primary host populations had not until recently been observed in the field in Europe, although gynoparae and alate males are produced in large numbers in autumn, and oviparae developed and laid numerous eggs which hatched to produce fundatrices on Crataegus monogyna under insectary conditions (Stroyan 1972b). However, apterae identified as this species were recently collected in July on a Crataegus sp. in Turkey (Şenol et al. 2014b). 2n=8.

Rhopalosiphum sanguinarium McVicar Baker Apterae are reddish with a strong pulverulent wax secretion (cf. oxyacanthae). On Crataegus pubescens in Mexico. Progeny of alatae from Crataegus have been successfully reared on grasses. Oviparae have been found on C. pubescens in Mexico in December, and can be distinguished from those of oxyacanthae (Remaudière & Remaudière 1997, p. 309-310), but apart from the difference in life the spring forms of the two species are almost indistinguishable.

Richardsaphis Kanturski & Barjadze

Aphidinae: Macrosiphini

One North American species on Potentilla originally described in Myzaphis, but with 2 hairs on first tarsal segments (as opposed to 5 in Myzaphis). Also, apterae have a wrinkled dorsum, and alatae have rhinaria on ANT V and no solid dark dorsal abdominal patch.

Richardsaphis canadensis (Richards) Apterae are pale green to yellow; BL c.1.5-1.6 mm. Alatae have secondary rhinaria distributed ANT III 6-13, IV 1-4, V 1-3. Described from Potentilla fruticosa in Ontario, Canada, and Jensen (aphidtrek.org) found oviparae and alate males on this host plant in September in New Mexico. Kanturski et al. (2018b) provided descriptions of all morphs.

Roepkea Hille Ris Lambers

Aphidinae: Macrosiphini

One (or two) palaearctic species, resembling Nearctaphis but without marginal abdominal tubercles, and the primary host is Prunus rather than Pyroideae.

Roepkea marchali (Borner) Plate 9f Apterae on Prunus are dirty yellowish-green to almost black, according to the degree of dorsal sclerotisation; BL 1.5-2.3 mm. They feed in spring on the undersides of leaves of Prunus mahaleb, which become rolled into broad tubes, inflated and yellowed. Alatae have a black dorsal abdominal patch and antennae with numerous secondary rhinaria distributed III 56-76, IV 17-30, V (0-)2-6 (Patti & Barbagallo 1997). In southern Europe (France, Italy) populations remain on P. mahaleb throughout the summer and produce oviparae without host alternation, but at least in Italy there is a partial migration, because summer colonies have been found on Galeopsis angustifolia, and these produced alate gynoparae and males that migrated back to Prunus (Barbagallo & Patti 1998). In eastern Europe and south-west Asia, host alternation to form colonies in flower calyces of Lamiaceae (Stachys, Phlomis) seems to be a more regular occurrence. This eastern form, which is recorded from Crimea, Georgia, Israel, Iran, Lebanon and Turkey, has a shorter antennal terminal process, and the apterae on Prunus generally have dark dorsal cross-bands rather than a completely sclerotic tergum. It was treated as a subspecies by Hille Ris Lambers (1966a), who applied the name R. marchali ssp. bathiaschvili Abashidze. However, this name was regarded as a nomen nudum by Remaudière & Remaudière (1997), so if the eastern form should prove to be distinct then another name may have to be found. Apterae on secondary hosts are smaller, dirty yellow-green (moss-coloured), with variably-developed olive-green dorsal markings, and have BL 1.2-1.7 mm. 2n = 12.

Rostratusaphis Fang & Qiao

Aphidinae: Aphidini

One species on Rhododendron in China with a very long hairy R IV+V.

Rostratusaphis rhododendronitos Fang & Qiao Apterae are black in life with some wax powder, BL 1.0-1.8 mm. The single described alata has secondary rhinaria distributed ANT III 6, IV 2. In colonies on young branches of Rhododendron simsii in Guizhou Province, south-west China (Fang & Qiao 2009). The life cycle is unknown.

Rubiaphis Stekolshchikov & Novgorodova

Aphidinae: Macrosiphini

One species on Rubus in Central Asia, differing from other Macrosiphini in having the spiracles on the first and second abdominal segments well separated.

Rubiaphis altica Stekolshchikov & Novgorodova Apterae are pale, semitransparent, BL 0.7-0.9 mm. On Rubus idaeus, feeding singly on the undersides of the leaves along the veins. In the Altai Republic, Russia (Stekolshchikov & Novgorodova 2020). The life cycle is unknown.

Ryoichitakahashia Hille Ris Lambers

Aphidinae: Aphidini

One species in Japan, resembling Aphis in its general appearance and arrangement of marginal tubercles, but with numerous marginal hairs on abdominal segments, with somewhat developed antennal tubercles, giving the front of the head a concave outline in dorsal view, and with secondary rhinaria on ANT III (and sometimes IV) in apterae.

Ryoichitakahashia prunifoltae (Shinji) Apterae are broad-bodied, rather dull reddish-black with banded antennae, central sections of tibiae pale and jet black siphunculi (see Moritsu 1983, as Macchiatiella ilexis); BL 2.1-2.2 mm. In dense colonies on stems of Ilex serrata (var. sieboldii) in Japan. Alatae have a black dorsal abdominal patch. The nomenclature is confused; Hille Ris Lambers (1965) pointed out that this aphid was illustrated by Shinji (1941) under the name Anuraphis celastri. The life cycle is unstudied; oviparae were collected on Ilex in early November (BMNH collection, leg. M. Sorin), but it is not known whether host alternation occurs.