Aphis, Linnaeus, 1758

Nieto Nafría, Juan M., Ortego, Jaime, Moreno-González, Víctor & Durante, M. Pilar Mier, 2022, The genus Aphis (Hemiptera, Aphididae) living on Asteraceae species in southern South America: Argentina and Chile, with five new species, Zootaxa 5183 (1), pp. 439-463 : 460-462

4. Identification key to viviparous females of Aphis species living on Asteraceae species known in southern South America

The identification keys for animals of any type always refer to the known taxa in a certain zoological group in a specific territory, sometimes some limitation is included. A key that includes all the species of the genus Aphis known in this part of South America would be impractical, due to the high number of species to be included, and it would undoubtedly be partial, since it is very possible that there are yet numerous species to be described. Keys limited to aphids collected on species of the same genus are already sufficiently covered by the work of Blackman & Eastop (2021). The key to the viviparous females of the genus Aphis from southern South America ( Argentina plus Chile) that is presented here, includes a limitation: host plant of aphids to be identified must belong to the family Asteraceae .

The distinguishing characteristics between aphid species frequently show overlaps, which can be very wide in the quantitative ones, thus the identifications should be made using several apterous viviparae, 6 to 15 for example, and when possible, some alate viviparae. Each obtained identification must be subsequently verified with the species description.

Characteristics that are used correspond to the apterous viviparae and should be taken with caution for alate viviparae, especially those relating to measurements and sclerotization. Characteristics that have no counterpart in the other proposition of the couplet are presented into brackets. Some features of the alate viviparous are included in curly brackets for informational purposes and although they are not always discriminating.

This key is indebted to those by Blackman & Eastop (2021), Mier Durante et al. (2003) and Nieto Nafría et al. (2019a, 2019b).

1 ANT and tibiae, except a small proximal portion of ANT.III, very black and as dark as SIPH and cauda, and with SEC SEN on ANT.III and ANT.IV, usually in greater quantity in ANT.IV. {Alatae: ANT IV with many SEC SEN}.......... A. lugentis

- ANT and tibiae mostly pale, without SEC SEN on ANT IV, and with or without SEC SEN on ANT.III. {Alatae: ANT.IV without or with few SEC SEN}................................................................................ 2

2 ANT.VI.PT usually 1.9 times thanANT.VI.B at least; exceptionally not so long, thenABD.2–6 is widely sclerotized, usually with discal plate (specimens A. craccivora ), or cauda carry at least 7 ST (specimens of A. fabae , A. solanella and A. spiraecola ). 3

- ANT.VI.PT usually 1.8 times than ANT.VI.B at most; exceptionally it can be longer, then MG TUB are no turgid, with wrinkles or warts ( A. ingeborgae ), or big and very numerous ( A. papillosa ), or TH MG areas are rough ( A. gutierreziae ), or SIPH are minuscule ( A. malalhuina ), or clypeus is somewhat swollen ( A. mirabilis ), or URS 1.2–1.4 times HT.2 and sometimes antennae five-segmented ( A. melosae form dwarf )................................................................. 13

3 ABD.1–5 entirely or widely membranous or with spino-pleural bands; if bands are present, bands are usually separated from each other, ABD.2–5 present no MG sclerites and ABD.8 carry 4 or more ST..................................... 4

- ABD.1–5 usually widely sclerotized, if only separated bands are present, then MG sclerotization exists and ABD.8 carries only 2 ST............................................................................................... 9

4 ABD.8 with 4 ST at least, if exceptionally only 2, then ANT.I is darker than ANT.II. ABD.8 with thick and dark brown to black transversal band. {Alatae: ABD.2–5 usually with some type of spinal sclerotization}............................... 5

- ABD.8 with only 2((4)) ST. ABD.7 and ABD.8 entirely membranous or with thin and brown or pale brown bands or sclerites. {Alatae: ABD.2–5 with poor or without spinal sclerotization}................................................. 7

5 Tarsal formula 3.3.3. ANT.I brown (dark brown to black in most pigmented specimens) contrasting with pale ANT.II and basal half of ANT.III.ABD.2–5 usually without spinal sclerotization. {Alatae: ABD.2–6 usually without spino-pleural sclerotization; SEC SEN: 14–40 on ANT.III, and 0(2) on ANT.IV}............................................... A. asclepiadis Tarsal formula 3.3.2. ANT.I as pigmented as ANT.II, and both contrasting with most part of ANT.III and ANT.IV. {Alatae: ABD.2–ABD.6 usually with spino-pleural bands, sometimes absent on some segments. ANT.III with less than 25 SEC SEN} ................................................................................................... 6

6 URS 0.8–1.1 times HT.2. ANT.III ST (17)35–69 μm (OnlY less than 30 μm in dwarf aestivating specimens). ABD.2–4 MG ST 0.19–0.42 times SIPH........................................................................... A. fabae

- URS 1.0–1.3 times HT.2. ANT.III ST 15–30(35) μm, ABD.2–4 MG ST 0.06–0.19 times SIPH............... A. solanella

7 ANT.I, ANT.II and very proximal part of ANT.III pale contrasting with dark brown to black of the rest of ANT. SIPH about 2 times cauda, both dark, and midway constriction of cauda poor marked. {Alatae: on ABD.5 with MG sclerites and ABD.6– ABD.8 with transverse bands; ANT.III, ANT.IV and ANT.V with 6–15, 7–8 and 0-4 SEC SEN, respectively}. A. coreopsidis

- ANT.I and ANT.II brown and both contrasting with the most part of ANT.III and ANT.IV. SIPH 0.8–2.5 times cauda, which is more or less finger-shaped. {Alatae: ANT.IV with 5 SEC SEN at most, if present}................................. 8

8 Cauda brown, dark brown or smoky and usually paler than black SIPH (exceptionally cauda dark like SIPH), with midway constriction not always well marked and with distal part relatively thin, and carrying 4–8(13) ST. {Alatae: ABD.7 and ABD.8 with transverse bands usually as dark as MG ABD.2–6 patches. ANT.III with 3–15 SEC SEN and ANT.IV without them}.............................................................................................. A. gossypii

- Cauda dark brown to black, as dark as SIPH, with midway constriction well marked and widened in its distal portion, and carrying 6–17 ST. {Alatae: ABD.7 and ABD.8 with transverse bands paler than MG ABD.2–6 sclerites or inconspicuous. ANT. III and ANT.IV with 6–11 and 0–5 secondary sensoria respectively................................... A. spiraecola

9 ABD segments with wide spinal-pleural bands and in addition ABD.2–6 with MG patches. {Alatae: ABD.2–5 without spinal and pleural sclerites. ANT.III and ANT.IV with 10–14 and 5–6 SEC SEN respectively}.......... A. rogerblackmani sp n.

- ABD.2–5 (sometimes from TH.3 and to ABD.6) with a discal plate, or with an extensive spino-pleural plate plus more MG patches; sometimes these plates with holes or partially disaggregated in bands. ABD.7 and ABD.8 with thick transverse bands .................................................................................................. 10

10 ANT.III usually —in 75% of specimens— with SEC SEN. ST on ANT.III 13–30 µm and 0.6–1.4 times ANT.III-BD. (TH.1)ABD.2–ABD.5(6) with a spino-pleural plate irregularly edged, sometimes coalescing with marginal patches or with white holes or intersegmental lines. {Alatae: ABD.1–5 usually without spino-pleural sclerotization. ANT.III mostly dark}... .................................................................................................. 11

- ANT.III without SEC SEN. ST on ANT.III 8–19 µm and 0.2–0.8 times ANT.III-BD. Discal plate (TH.1 to ABD.6) usually present, sometimes transformed into a partial or complete spino-pleural plate plus marginal patches, from most anterior segments. {Alatae with transverse band on mostly abdominal segments and ANT.III pale on a long proximal portion}.... 12

11 COM MARG TUB absent. URS 0.12–0.15 mm and 0.8–1.0 times HT.2. {Alatae: ABD.1–4 with isolated spinal sclerites, ABD.5–8 with transverse bands, ABD MG sclerites big. ABD.7 MG TUB always present and as big as ABD.1 MG TUB. ANT. III with 10–13 SEC SEN}....................................................................... A. intrusa

- COM MARG TUB usually present (3–6). URS 0.14–0.17 mm and 1.1–1.3 times HT.2. {Alatae: ABD.1–6 with spinal sclerites or band, ABD.7 and ABD.8 with transverse band. ABD.7 MG TUB sometimes absent, if present, smaller than ABD.1 MG TUB. ANT.III, ANT.IV and ANT.V with 7–13, 0–4 and 0((2)) SEC SEN respectively}...................... A. melosae

12 URS (1.2)1.3–1.8 times ANT.VI.B and 1.1–1.5 times HT.2. When alive dull grey, by a cover of white wax powder on black body, turning black when fixed in ethanol. {Alatae: ANT.III and ANT.IV with 2–9, 0–1 SEC SEN respectively}.... A. intybi

- URS 0.8–1.2((1.4)) times ANT.VI.B, more than 1.2 in aestivating dwarf apterae) and 0.7–1.3 times HT.2. When alive bright black, without wax powder cover. {Alatae: ANT.III with 2–10 SEC SEN}.............................. A. craccivora

13 PR MG TUB absent. [ABD membranous, SIPH shorter than cauda; ANT III with 1–8 SEC SEN]. {Alatae: ANT.III and ANT. IV respectively with 4–9 and 0–3 SEC SEN}...................................................... A. paradoxa

- PR MG TUB present, exceptionally lacking ( A. papillosa and A. melosae form dwarf ) on ABD.7.................... 14

14 PR MG TUB not turgid, with wrinkles or warts. [ABD.2–6 with dark and wide spino-pleural bands and marginal patches. COM MG TUB if present, smaller and slenderer than the primary]. {Alatae without spino-pleural sclerotization on ABD.1–5(6). ANT.III with 3–7 SEC SEN}................................................................ A. ingeborgae

- PR MG TUB turgid dome-shaped (hemispherical, hemiovoidal)............................................... 15

15 COM MG TUB present, at least 4 in all.................................................................. 16

- COM MG TUB usually absent, if present, 3 at most........................................................ 20

16 SIPH 0.4–0.9 times cauda............................................................................. 17

- SIPH 0.9–1.6 times cauda............................................................................. 19

17 ABD.8 with 2–4 ST. URS 0.10–0.13 mm. {Alatae: ANT.III, ANT.IV and ANT.V respectively with 4–13, 1–4 and 0–2 SEC SEN}...................................................................................... A. fuentesi

- ABD.8 with 4–7 ST. URS 0.12–0.18 mm ................................................................. 18

18 MG TUB small, on ABD lower and narrower at the base than neighbouring seta.ANT.III ST 8 µm long and 0.4-0.9 times ANT. III-BD at most. ABD.7 MG TUB always present. {Alatae: ANT.III, ANT.IV and ANT.V respectively with 5–23, 0–7 and 0–3 SEC SEN}............................................................................ A. senecionicoides

- MG TUB big, on ABD usually taller and wider at the base than neighbouring seta. ANT.III ST 10 µm long and 0.6-2.3 times ANT.III-BD at least). ABD.7 MG TUB absent on 1 or both 2 sides in 60% of apterae and 80% of alatae. {Alatae: ANT.III and ANT.IV respectively with 1–14 and 0–5 SEC SEN}................................................ A. papillosa

19 COM MG TUB small, sometimes absent on ABD.7.ABD.8 with 2 ST. Cauda with 4–6 ST.ABD.1–ABD.5 always membranous. {Alatae: ANT.III with 4–8 SEC SEN}......................................................... A. coridifoliae

- COM MG TUB big. ABD.8 with 4–9 ST. Cauda with 7–14 ST. ABD.1–ABD.5 membranous or with sclerites. {Alatae: ANT. III and ANT.IV respectively with 6–7 and 0((1)) SEC SEN}......................................... A. conspicua

20 SIPH 0.2–0.7 times cauda. Body 12–50 times SIPH........................................................ 21

- SIPH 0.7–2.0 times cauda. Body 4.5–13.5 times SIPH, if more than 12 times then ANT.III ST shorter than 15 µm....... 22

21 SIPH 0.2–0.4 times cauda and 0.5–1.1(1.3) times its width at base Body 28–50 times SIPH. When alive black without wax grey powder or with a very small quantity. {Alatae: ANT III and ANT.IV respectively with 16–27 and 7–13 SEC SEN}................................................................................................ A. malalhuina

- SIPH 0.4–0.7 times cauda and 1.2–3.0 times its width at base. Body 12–17 times SIPH. When alive whit wax grey or white powder in very appreciable quantity. {Alatae: ANT III with 4–10 SEC SEN}....................... A. pulverea sp. n.

22 Cauda pale brown or smocked, darkening to brown on both sides and apex. [ABD.1–ABD.6 without segmental sclerotization, ABD.7 and ABD. 8 sometimes with sclerites or small transverse bands. Setae on ANT, TH, ABD, femora and tibiae pointed. URS pointed. Cauda thick from midway constriction that is no evident]. {Alatae: ANT III and ANT.IV respectively with 3–8 and 0((2)) SEC SEN}...................................................................... A. hyalis sp. n.

- Cauda homogeneously black or dark brown............................................................... 23

23 TH.2 with rough MG areas because of the remarkable thickness of the lines of the reticulation. ABD.1–7 usually membranous; small and pale post-siphuncular sclerite; ABD.8 sometimes with small sclerites. URS subrectangular (edge lines are parallel to each other for most of their length). [Setae of dorsum and mostly on antennae, femora and tibiae blunt. Cauda slender from midway constriction, which is small]. {Alatae: ANT III and ANT.IV respectively with 5–9 and 0((1)) SEC SEN}................................................................................... A. gutierreziae sp. n.

- TH.2 no rough, with thin lines of the reticulation. ABD.1–7 usually with sclerotization. URS triangular (edge lines convergent to apex)........................................................................................... 24

24 Clypeus quite swollen, well perceptible in specimens alive or preserved in ethanol, but not so easily perceptible in mounted specimens, on this check: maximal width of the clypeus 0.75–1.15 times minimal ventral distance between antennal alveoli, and maximal distance between the outer edges of the mandibular lamina 1.10–1.35 times minimal ventral distance between the antennal alveoli; see Nieto Nafría et al., 2022, Fig. 2 ). [ANT.VI.PT 1.1–2.3 times ANT.VI.B, frequently shorter than 1.5 and rarely longer than 1.9. SIPH 0.7–2.0 times cauda. URL 0.9–1.4 times HT.2. ANT.III ST 8–28 µm. ABD.8 ST 14–48 µm]. {Alatae: ANT III with 4–10 SEC SEN}........................................................... A. mirabilis

- Apterae with no swollen clypeus........................................................................ 25

25 URS 0.11–0.14 mm, 1.2–1.4 times HT.2 and 1.3–1.6 times ANT.VI.B. Cauda 0.9–1.1 times its basal width. ANT.III ST 10–33 µm and 0.6–1.3 times ANT.III-BD......................................... A. melosae (dwarf aestivating apterae)

- URS 0.09–0.11 mm, 0.8–1.1 times HT.2 and 0.9–1.3 times ANT.VI.B. Cauda 1.0–1.7 times its basal width. ANT.III ST 6–13 µm and 0.4–0.8 times ANT.III-BD...................................................... A. sanrafaelina sp. n.

Figures

FIGURE 2. Aphis rogerblackmani Nieto Nafría, Ortego & Mier Durante sp. n., alate viviparous female. A, complete view, with detail: ABD.1–3 MG, and ABD.8 (note in both the punctuation by spinules); B, ANT.III; C, ANT. VI. The scales vary according to specimens or parts photographed; see measurements in Table 1.