Material. 1 al., No. 10190, ChD, 1 km north of Pevek, rubble-loam foothill with spotty grass-semishrubs tundra vegetation, N 69 ° 42 ', E 170 ° 21 ', 1.vii. 2011, sweeping; 1 apt., No. 10191, ChD, 1 km north of Pevek, N 69 ° 42 ', E 170 ° 21 ', petty dry mountain terrace with forb-sedge-dryad spotty vegetation, 4.vii. 2011, sweeping; 1 al., No. 10192, ChD, 1 km north of Pevek, N 69 ° 42 ', E 170 ° 21 ', dry mountain terrace with spotty forb-lichen-dryad vegetation, 4.vii. 2011, sweeping; 1 al., No. 10193, from the same locality as No. 10190, 7.vii. 2011, sweeping; 1 fund., 11 apt., 2 al. and 1 male, No. 10259, SSWBer, Castilleja pavlovii Rebr., 19.vii. 2012; 1 apt., 4 al., 10 males and 17 ovip., No. 10259 - 21.VII, from the same plant, locality and the same data, reared in laboratory conditions, 21–24.vii. 2012.
Distribution outside Chukotka AO. USA (California, Oregon) and Canada (Alberta, British Columbia, Manitoba).
Comments. Apterae and alatae of this species were collected by sweeping near Pevek in 2011, and on 19 July 2012 a colony of consisting of an old fundatrix, apterous and alate viviparous females, males, apteroid and alatoid nymphs was found at SSWBer feeding on flowers, upper sides of apical leaves and lower side of other leaves of Castilleja pavlovii Rebr. Apteroid and alatoid nymphs were transferred to plants in laboratory conditions, where several more males and oviparous females was reared.
One apterous and 3 alate viviparous females were collected by sweeping on 1–7 July 2011 in Chaunskiy District near Pevek. In this locality N. castelleiae was found at a location with severe (dry and windy) conditions, where it inhabited situations on the foothill and montane terraces with patchy forb-semishrub and forb-dryad vegetation. Specimens from Chukotka differ slightly in morphology from individuals from other populations. Heie (1979) indicates that the siphunculi of this species are short (siphunculi of apterous viviparous female 150–230 Μm and 0.81–1.29 as long as cauda), and that their lengths vary depending on the population and the date of collection. We were able to examine a slide with two apterous viviparous females of N. castelleiae collected by A.G. Robinson on 19 July 1973 in Manitoba from the collection the Muséum national d'Histoire naturelle (Paris, France). They have short siphunculi— 129–166 Μm and 0.73–0.96 as long as length of cauda. Siphunculi of specimens from Chukotka are shorter— 116–152 Μm and 0.65–0.76 as long as length of cauda. Furthermore, there are several more additional setae on ultimate rostral segment of specimens from Chukotka (6–10) than indicated by Heie (6–8) or in aphids from Manitoba have (6–7). However, these differences are minor and do not go beyond the possible geographic variation.