Metopolophium sabihae Prior, 1976

Khruleva, Olga A. & Stekolshchikov, Andrey V., 2019, Additions to the aphid fauna of Wrangel Island due to climate change with redescription of the oviparous female of Pterocomma groenlandicum Hille Ris Lambers, 1952 (Hemiptera, Aphidoidea), Zootaxa 4615 (3), pp. 511-528 : 522-523

Metopolophium sabihae Prior, 1976

Until 2015, only fundatrices and oviparous females of Metopolophium sabihae had been collected on Wrangel Island. Today, all five morphs of this species have been found. Specimens from Wrangel Island are similar as those of European populations, differing mainly in the length of setae and in the number of secondary rhinaria on the 3rd antennal segment ( Table 2 ). In addition to these small differences in morphology, there are significant differences in the life cycle of British and Wrangel Island populations of M. sabihae : anholocyclic in the first case ( Prior 1976), holocyclic in the more severe climatic conditions of the second. These differences corroborate the tendency towards a change in life cycle and morphology in geographically separated populations of aphids ( Wieczorek et al. 2013; Kanturski & Barjadze 2018). The disjunct distribution of M. sabihae , along with its association on Wrangel Island with the driest and warmest biotopes and tundra-steppe vegetation, suggest a relictual presence in this Pleistocene refugium ( Stekolshchikov & Khruleva 2014).

Material. Somnitel’nye Mountains: dry slope of southern exposure with a forb-sedge and forb-dryad cover, 17.vii.2015, sweeping, 2 fund., 12 apt., 1 al., 1 male, 6 ovip. Mineeva Mountains: dry hillock with a spotted moss-willow-forb-grassy cover in the base of the slope of the southern exposure (70° 59.163 N, 179° 31.040 W), 19.vii.2015, sweeping, 1 apt., 2 males, 1 ovip. The middle reaches of the Mamontovaya River: dry gravelly-loamy (carbonates) slope of terrace of the southern exposition with spotted lichen-forb-grass-sedge cover and separate creeping willows (71° 08.233 N, 179° 42.668 W), 30.vi.2015, sweeping, 1 fund.; a dry rubbly loamy south-fac- ing slope of a shallow ridge with patchy cover of herbs and sedges (71° 08.390 N, 179° 43.620 W), 22.vii.2015, sweeping, 3 apt., 1 male, 9 ovip.; the same locality, 22.vii–5.viii.2015, pitfall trap, 1 apt. Spurs of the Mt. Pervaya: steep gravelly-loamy slope of western exposure with spotted grass and legume-dryad cover (71° 08.885 N, 179° 27.212 W, 241 a. s. l.), 13.vii–5.viii.2015, pitfall trap, 1 ovip. The upper reaches of the Neizvestnaya River: dry gravelly plots on the edge of a high river terrace of the southern exposition with forb-sedge cover (71° 12.970 N, 179° 19.387 W), 21.vi.2015, sweeping, 23 fund.; the same localities, 4–8.vii.2015, yellow pan trap, 1 fund.; the same localities, 5.vii.2015, sweeping, 21 fund., 8 apt.; the same localities, 12.vii.2015, sweeping, 12 fund., 39 apt., 8 al., 1 male, 33 ovip.; the same localities, 12–27.vii.2015, pitfall trap, 1 al., 3 ovip.; the same localities, 12–29.vii.2015, pitfall trap, 1 apt., 1 male, 7 ovip.; the same localities, 29.vii.2015, sweeping, 1 apt., 2 ovip.; 29.vii–3.viii.2015, pitfall trap, 1 apt.; a dry south-facing slope of monadnock with patchy cover of herbs and sedges (71° 11.273 N, 179° 19.255 W), 8.vii.2015, sweeping, 6 fund., 3 apt.; the same locality, 23.vii.2015, sweeping, 2 apt., 6 ovip.

Biology. In 2015, the abundance of M. sabihae on Wrangel Island had increased, as suggested by new records from biotopes previously searched. Despite the presence of a winged morph, M. sabihae was absent in the yellow pan traps albeit was abundant in the sweep samples taken in the same biotopes. In 2015, M. sabihae was the most widespread and abundant aphid species on the island. It was collected in all five well-studied areas in the mountainous part of the island and absent only on the southern plain. Despite the increased abundance, the species did not show an expansion in the type of biotopes inhabited. Also, as before, the species occurred almost exclusively on the driest and warmest areas confined to the southern slopes of hills and river terraces with tundra-steppe vegetation ( Fig. 15 ). This fact indicates a close connection of the species with these habitats and confirms its status as a tundra-steppe relict.

Previously, fundatrices were recorded in different years from mid-July to mid-August, whereas oviparous females occurred only from late July to mid-August. The data on the phenology of the species in 2015 indicate a much earlier appearance of fundatrices; on the 21st of June, they were present in sweep samples ( Table 3 ). The next generation (apterous viviparous females) were collected in early July. The largest number of aphids of this species was taken in mid-July. At that time, in the central and southern parts of the island, all morphs were present, of which apterous viviparous and oviparous females were especially numerous. At the end of July, the abundance of aphids collected by sweeping decreased, and at that time, oviparous females were mainly recorded.

Figures

FIGURE 15. A tundra-steppe assemblage on the edge of a south-facing river terrace in the upper reaches of the Neizvestnaya River (central part of the island), 23.vi.2015; a biotope where the greatest number of Metopolophium sabihae was collected.