Uroleucon nahuelhuapense Nieto Nafría & von Dohlen, 2019

Nafría, Juan Manuel Nieto, Von Dohlen, Carol D., Moreno-González, Víctor, Ortego, Jaime & Durante, M. Pilar Mier, 2019, The species of Uroleucon (Hemiptera: Aphididae) living on Adesmia (Fabaceae) in Argentina, with the description of a new species, Zootaxa 4555 (4), pp. 561-572 : 563-570

Uroleucon nahuelhuapense Nieto Nafría & von Dohlen , sp. n.

Types. Holotype: apterous viviparous female, ARGENTINA, Neuquén province, Villa La Angostura: Santa María (road 231, km. 32), 40° 55 'S 71° 26’ W, 800 m; on Adesmia boronioides ; December 14, 2009; Mier Durante, Ortego and Nieto Nafría leg., sample ARG 1670 , specimen number 1; collection of the University of León (León, Spain) . Paratypes: 32 viviparous apterous females of the same sample, collected at the same time as the holotype; collections of the University of León (León, Spain ), Jaime Ortego (Mendoza, Argentina ) and The Natural History Museum ( London , United Kingdom ) .

Apterous viviparous females. Figure 1 . Based on 33 specimens. Colour when alive bright emerald green with brownish-green siphunculi. Body 2.90-3.53 mm long and pear-shaped with long legs and antennae. Mounted specimens more-or-less light brown with darkened head, rostrum, anal plate, cauda and usually antennae and legs, and brown to dark-brown siphunculi. Setae on dorsum of body, antennae and legs (except those on tarsi and end of tibiae) thick and with apex indistinct or truncate; other setae more-or-less pointed. Marginal tubercles absent. Several specimens have one or two very minute cephalic spinal tubercles. Frons sinuous, medial-frontal tubercle lower than the frontal-lateral (or antennal) tubercles. Cephalic setae with the more usual pattern in the South American species of the genus: behind the four aligned frontal setae there are from front to back one pair (anterior discal), one pair (posterior discal) and a transverse postero-cephalic line with four setae. Antennal segments I and II similar in colour to head or in part darker than it, especially around the ventro-medial muscular impressions of segment I and near the end of segment II; antennal segment III smooth as in the proximal ones, with a short proximal part pale brown as in the proximal segments and progressively darkened to a dark brown or near-black apical ring; remainder of antenna progressively darkened and imbricated. Sensoria round and with thick walls; primary sensoria ciliate; secondary sensoria small, non-protruding and aligned, with the most proximal one at the end of the paler part of the segment. Rostrum surpassing middle coxae and darkening to apex. Ultimate rostral segment relatively narrow. Coxae and trochanters more-or-less pigmented than head and most of femora, which present a more-or-less extensive dorso-apical area darker than the remaining segments. Tibiae somewhat darker than the femora and with 1/7-1/8 of their length apical dark brown or almost black. Tarsi short and as dark as the distal end of tibiae and second segment with ventral setae. Setiferous sclerites on thorax and on pre-siphuncular abdominal segments small or very small, mostly unpigmented, near inconspicuous. Pre- and post-siphuncular sclerites absent. Intersegmental muscular sclerites absent. Spiracular sclerites small and light brown. Siphunculi progressively pigmented, brown to dark brown, cylindrical with enlarged proximal part, in most of the length a little wider than hind tibiae; transverse striae in the paler anterior half, scales progressively more marked on the distal portion prior to reticulation, which is ill defined; flange little marked. Setiferous sclerites on abdominal segments 6 to 8 and more-or-less light pigmented; those on VIII segment can be partially fused, without forming a continuous transverse sclerite. Subgenital plate pale, not darker than the ventral part of anterior abdominal segment and paler than anal plate and cauda, which are scarcely pigmented. Cauda lanceolate, with a marked proximal narrowing and more-or-less blunt at the apex; its setae are all similar in length and longer than the caudal width at the middle. Metric and meristic features in Table 2.

Alate viviparous females and sexuales. Unknown.

Etymology. The specific name nahuelhuapense is a supposed demonym of Nahuel Huapi lake, in neutral gender because Uroleucon is neutral.

Bionomics. Aphids feed on the small stems of Adesmia boronioides Hook. f. ( Fabaceae ), which is its only known host plant. Sexuales are unknown, but the species is likely to be holocyclic, because of cold temperatures during winter.

Geographical distribution. The new species is currently known in one locality of the Andean slopes of the Argentinean province of Neuquén, very close to the shore of the Nahuel Huapi lake. It is possible that the species occurs on the same plant species or on other species of Adesmia in other localities of similar altitude in Argentina or even in Chile.

Molecular analyses. Amplification and sequencing of the tRNAleu-COII locus were performed successfully and resulted in divergent sequences for all South American taxa. Sequences obtained were deposited in GenBank ( Table 1).

Taxonomic discussion. M.P. Mier and J. Ortego had some difficulty in 2008 convincing reviewers of the manuscript describing U. adesmiae that the new species should be classified as Uroleucon , because its host plant was in Fabaceae , not Asteraceae or Campanulaceae , the usual host-plant families of Uroleucon ( Mier Durante & Ortego, 2008) . Furthermore, several morphological features of U. adesmiae were not typical of Uroleucon (almost total absence of setiferous sclerites as well as pre- and post-siphuncular sclerites). Justification of U. nahuelhuapense sp. n. as a Uroleucon is simpler because there is a great resemblance to U. adesmiae and U. payuniense Ortego & Nieto Nafría 2007 (see Mier Durante & Ortego, 2008), and because it shares the genus of host plant with U. adesmiae .

This classification is further justified by genetic evidence. The tRNAleu-COII mitochondrial sequences confirm the correct placement of U. nahuelhuapense sp. n. (as well as U. adesmiae ) within Uroleucon ( Figure 2 ). Both species living on Adesmia form a cluster with other South American native Uroleucon and one Euro-Asiatic species, U. rapunculoidis (Börner, 1939) . While U. nahuelhuapense sp. n. and U. adesmiae are clustered most closely to each other, the magnitudes of their pairwise patristic distance (sum of branch lengths on the dendrogram) and Tamura-Nei distance are as great or greater than the distances between other established, valid species in the comparison ( Table 3). Thus, these two taxa exhibit species-level genetic distances from each other and from other described Uroleucon , both South American and Northern Hemisphere species.

It is generally accepted that the subgeneric classification of Uroleucon requires a thorough revision (see Blackman & Eastop, 2018). Our phylogenetic studies of Uroleucon in progress suggest that the South American species are not a monophyletic group, and that the subgenera as currently understood are not monophyletic (see also Moran et al., 1999). Until the necessary revision can be undertaken, however, it seems appropriate to place Uroleucon nahuelhuapense sp. n. in the subgenus Lambersius Olive, 1965 , according to the concept of that subgenus in Nieto Nafría et al. (2007).

Uroleucon nahuelhuapense sp. n. and U. adesmiae , the two species of Uroleucon living on Adesmia species, can be morphologically distinguished from one another by antennal pigmentation (darker in U. nahuelhuapense sp. n. than in U. adesmiae ) and by different numbers of setae on the cephalic dorsum, on the ultimate rostral segment, on both dorsum and venter of abdominal presiphuncular segments, on genital plate and on cauda (see Table 2).

Thirty species of Uroleucon have been recorded from South America: U. adesmiae Mier Durante & Ortego, 2008 , U. aeneum (Hille Ris Lambers, 1939) , U. ambrosiae (Thomas, 1878) , U. bereticum (Blanchard, 1922) , U. brevisiphon de Carvalho, 1998 , U. chilense (Essig, 1953) , U. compositae (Theobald, 1915) , U. erigeronense (Thomas, 1878) , U. essigi de Carvalho, 1998 , U. eumadiae Delfino & Gonzales, 2005 , U. garnicai Delfino, 1991 , U. gochnatiae Delfino, 1994 , U. gravicorne (Patch, 1919) , U. jaceae (Linnaeus, 1758) , U. littorale (Blanchard, 1939) , U. macolai (Blanchard, 1932) , U. malarguense Ortego & Nieto Nafría, 2007 , U. mendocinum Mier Durante & Ortego, 2007 , U. muermosum (Essig, 1953) , U. nahuelhuapense sp.n., U. nuble (Essig, 1953) , U. patagonicum Nieto Nafría & Seco Fernández, 2007 , U. payuniense Ortego & Nieto Nafría, 2007 , U. petrohuense de Carvalho, 1998 , U. pseudomuermosum de Carvalho, 1998 , U. riojanum Nieto Nafría & Mier Durante, 2007 , U. rudbeckiae (Fitch, 1851) , U. sonchi (Linnaeus, 1767) , U. tessariae Delfino, 1994 and U. tucumani (Essig, 1953) . Four of them: U. aeneum , U. compositae , U. jaceae and U. sonchi are species wide-distributed and not native to the Americas, they can be easily separated to the others 26 species, which are South American or North American native species, because they have coxae wholly dark brown to black, as pigmented or nearly as pigmented as distal apices of femora, tibiae and most part of siphunculi, which are dark-brown to black sometimes with paler middle portion. In other 26 species coxae are yellowish brown to brown, less pigmented than distal part of siphunculi and usually less pigmented than the distal area of femora, and siphunculi are variably pigmented but if the middle part is not as dark as proximal and distal part then cauda is triangular shaped, not lanceolate.

Most part of these 26 species are restricted to South America, only U. ambrosiae (Thomas, 1878) , U. erigeronense (Thomas, 1878) , U. gravicorne (Patch, 1919) and U. rudbeckiae (Fitch, 1851) are also known in North America.

parentheses are exceptional data, or very exceptional if parentheses are duplicates. Bold characters in the Uroleucon

adesmiae column indicate that the previously known corresponding limit has been modified with the new data. Arrows,

single or double, indicate the most important characteristics to differentiate both South American species of Uroleucon

living on Adesmia .

......continued on the next page

The following key permits the separation of the Uroleucon species with relatively pale coxae, as it has been detailed before, recorded from South America. It is based on that by Nieto Nafría et al. (2007), which in turn was based on the key by de Carvalho et al. (1998); several disjunctive couplets have been simplified.

Uroleucon littorale was described from a locality in the Argentine province of Entre Ríos, it has not yet been collected and its original description is not too eloquent; it is very similar to U. tucumani , of which it can be synonymous in opinion by Blackman & Eastop (2018); it is not included in the key.

The measurements are lengths unless otherwise indicated. In brackets are morphological data which do not have correspondence in the other proposition of the disjunctive, but which are useful to secure identification.

Information on the distribution of each species has been actualized from our bibliographic registers. It includes countries for South America, regions for Chile and provinces for Argentina. Records from the Federal Capital of Argentina, Ciudad Autónoma de Buenos Aires, are joined to records from the Buenos Aires province. The names of Chilean regions Aysén del General Carlos Ibáñez del Campo, Libertador General Bernardo O’Higgins and Metropolitana de Santiago are simplified respectively to Aysén, O’Higgins and Santiago.

1 Ventral hairs on proximal 2/3 of hind tarsi second segment small or atrophied. [Siphunculus 1.0–1.2 times cauda. Marginal tubercles present on abdominal segment 2 to 5. Alatae with protuberant secondary sensoria on antennal segment III. Green in life]. On composite species, mainly of genera Erigeron and Solidago. Probably Neartic in origin; Brazil, Colombia, Venezuela......................................................................................... U. gravicorne

- Ventral hairs on proximal 2/3 of hind tarsi second segment similar in shape and length to others ventral hairs on this segment and on other tarsi.................................................................................... 2

2 Antennal segment VI processus terminalis longer than 1.2 mm. Siphunculi at least 2.3 times cauda, thin, brown with a pale proximal portion, and reticulated at most on 15% of total length. [Probably pale green with brown o brownish head and partially appendages and siphunculi when alive.] On Senecio smithii, Symphyotrichum squamatus and perhaps other composite. Chile: Aysén, Ñuble.............................................................................. U. nuble

- Antennal segment VI processus terminalis shorter than 1.00 mm. Siphunculi shorter or longer than 2.3 times cauda, but if longer it has a different appearance or pigmentation or reticulation of those mentioned above........................ 3

3 Posterior part of cephalic dorsum (behind the discal two setae of vertex) with 6–11 setae............................. 4

- Posterior part of cephalic dorsum (behind the discal two setae of vertex) usually with 4 setae (the general feature in the genus)................................................................................................... 6

4 Cauda triangular or long-pentagonal and 0.22‾ 0.30 mm. Abdominal segment 2 to 6 with 1‾2 marginal setae each side [and 5‾13 spinal and pleural setae]. Red with siphunculi dark brown when alive. [Siphunculi brown to dark brown in general often with a less pigmented middle portion]. On Mutisia spinosa . Argentina: Chubut and Neuquén ............. U. patagonicum

- Cauda lanceolate and 0.27–0.40 mm. Abdominal segments 2 to 4 with 3 or more marginal setae each side. Green or brownish green in life......................................................................................... 5

5 Siphunculi yellowish or very light-brown with paler proximal 1/4. Abdominal segments 2 to 6 with 6‾12 marginal setae each side and 16–27 setae on spinal and pleural areas. Antennal segment VI processus terminalis at least 1.0 times antennal segment III. Siphuncular width at the base 2.4–4.3 times its width at the beginning of the reticulation, which is well sculptured and extends over 12.2–18.9% of its length. Ultimate rostral segment with 7–10 accessory setae. Cauda with 6–9 setae. Dorsoabdominal setae 50–60 µm. Green in life. On Grindelia chiloensis. Argentina: Mendoza ................... U. payuniense

- Siphunculi homogeneous brown. Abdominal segments 2 to 6 with 3–6 marginal setae each side and 7–20 setae on spinal and pleural areas. Antennal segment VI processus terminalis at most 1.1 times antennal segment III. Siphuncular width at the base 1.6–2.9 times its width at the beginning of the reticulation, which is poorly sculptured and extends over only 8.0–13.4% its length, exceptionally to 14.3%. Ultimate rostral segment with 10–15 accessory setae. Cauda with 10–15 setae. Dorsoabdominal setae 35–45 µm. Dark green to brownish green in life. On Adesmia . Argentina: Chubut and Neuquén ...... U. adesmiae 6 Dorso-cephalic setae 18‾36 µm. [Greenish yellow to yellowish pale green in life. Siphunculi with paler proximal portion, more evident in alatae than apterae. Antennal segment III with 4‾25 secondary sensoria on proximal 1/ 2 in apterae and 20‾41 secondary sensoria in alatae]. On species of several composite genera, in South America Baccharis, Conyza, Erigeron, Gutierrezia, Haplopappus and Hysterionica. Nearctic introduced species; Brazil, Colombia, Peru, Venezuela; Argentina: Buenos Aires, Córdoba, Entre Ríos, Jujuy, Mendoza, Salta, San Luis, Santa Fe, Santiago del Estero; Chile: Maule, Santiago, Valparaíso ...................................................................................... U. erigeronense

- Distal setae on cauda variable in length, if shorter than other caudal setae then usually pointed. Dorso-cephalic setae 30‾75 µm.................................................................................................... 7

7 Ultimate rostral segment 0.21‾ 0.27 mm and 1.5‾1.8 times hind tarsi second segment.............................. 8

- Ultimate rostral segment 0.12‾ 0.22 mm and 0.8‾1.4 times hind tarsi second segment.............................. 9

8 Ultimate rostral segment 0.23‾ 0.27 mm, with 6‾10 accessory setae. Dark reddish to brown or black when alive. On Acrisione denticulata and perhaps on species of Senecio . Brazil; Chile: La Araucanía, Los Lagos ................... U. muermosum

- Ultimate rostral segment 0.21‾ 0.23 mm, with 18–24 accessory setae. Shiny green in life. On Madia chilensis and M. sativa . Chile: Santiago .............................................................................. U. eumadiae

9 Marginal tubercles protuberant, frequently on abdominal segment 5 and sometimes on abdominal segments 2 to 4. Ultimate rostral segment with 4‾5 accessory setae. [Apterae with 14‾26 secondary sensoria distributed on nearly whole length of antennal segment III.] Probably pale green in life. On unknown composite. Chile: Los Lagos .................. U. petrohuense

- Marginal papillae absent on abdominal segment 5, if present on abdominal segments 2 to 4 then not protuberant. Ultimate rostral segment usually with 5 or more accessory setae......................................................... 10

10 Antennal segment VI processus terminalis at most 3.8 times antennal segment VI base. Siphunculi reticulated on at least 35% of their length and yellowish brown to light brown, like cauda, which is lanceolate. Dark-green with dark-brown head. On Baccharis, Gochnatia glutinosa, Gutierrezia, Hyaloceris cinerea and Senecio subulatus . Bolivia; Argentina: Catamarca, Jujuy, La Rioja, Mendoza, Salta, Tucumán ............................................................... U. gochnatiae

- Antennal segment VI processus terminalis usually at least 3.8 times antennal segment VI base; if 3.1‾3.9 times then siphunculi or cauda have different features to above indicated......................................................... 11

11 Antennal segment III in apterae with 2‾4 small secondary sensoria occupying 33% (exceptionally to 44%) of the segment length, which is short (0.49‾ 0.61 mm); alatae unknown. [Marginal tubercles absent. Setiferous and postsiphuncular sclerites present. Coxae more pigmented than trochanters and 1/2‾2/3 proximal portion of femora. First tarsal segments with 5 setae. Siphunculi 1.5‾1.7 times cauda, with groups of spinules homogeneously distributed below the reticulated portion, which is 19.6‾25.5% of the total length. Cauda light-brown, with 9‾14 setae.] Brown to red-brown in life. On Hypochoeris . Bolivia; Argentina: Mendoza ....................................................................... U. malarguense

- Antennal segment III of both apterae and alatae usually with 5 or more secondary sensoria, but if 2‾ 4 in apterae then all the above-mentioned characters into square-brackets of precedent proposition are not presented together................. 12

12 Siphunculi very robust (approximately 2 times larger than the hind tibiae and 0.58‾ 0.80 mm), subcylindrical (somewhat inflated at beginning of reticulation), slightly curved outside, without flange, approximately basal 1/4 as pale as coxae and rest brown to dark-brown (as dark as tibiae or antennae), nearly smooth on pale proximal portion, progressively wrinkly to a scaly on dark middle portion, and reticulation extends on 21‾41% of its length. Green in life. On Gutierrezia iserni. Argentina: La Rioja..................................................................................... U. riojanum

- Siphunculi with different feature, usually as large as hind tibiae or thinner than them............................... 13

13. Siphunculi usually at least 1.6 times cauda, which is 0.24‾ 0.47 mm and can have 13 or less setae or 17–27 setae, if more than 17 then ultimate rostral segment 1.1–1.4 times hind tarsi second segment, and antennal segment VI processus terminalis at most 4.1 times antennal segment VI base and antennal segments I and II paler than most of the antennal flagellum........ 14

- Siphunculi usually at most 1.6 times cauda, which is 0.30‾ 0.83 mm and has 9‾31 setae........................... 18

14 First tarsal segments with 3 setae. Siphunculi shorter than 1.8 times caudal length. [Antenal segment III with 2–8 secondary sensoria in apterae (restricted to proximal half) and 6–22 in alatae]. Pale to medium-green in life. On Baccharis species and Hysterionica jasionoides. Argentina: Catamarca, La Rioja, Mendoza, San Juan; Chile: Coquimbo ................ U. essigi

- First tarsal segments usually with 4–5 setae, if only 3 setae present then siphunculi 1.8–2.3 times cauda................ 15

15 Apterae with 2–11 secondary sensoria restricted to proximal half. Antennal segment VI processus terminalis 0.7–0.9 times antennal segment III and 3.2–4.1 times antennal segment VI base; ultimate rostral segment 1.1–1.4 times hind tarsi second segment, which is 0.13–0.17 mm; siphunculi 0.69–0.92 mm and 1.7–2.3 times cauda, which is 0.34–0.47 mm. Setae on antennal segment III 28–45 µm. On Adesmia boronioides . Bright emerald green in life. Argentina: Neuquén ..................................................................................................... U. nahuelhuapense sp.n.

- Apterae with 4–16 secondary sensoria extending over most of length of segment. Other above-mentioned characters are not presented together. On species of Asteraceae .............................................................. 16

16 Antennal segment VI processus terminalis 5.5‾6.6 times antennal segment VI base. First tarsal segments with 3‾5 setae. Siphunculi yellowish-brown to light-brown [and 1.8–2.3 times cauda]. Pale green in life. On Pluchea absinthioides . Argentina: Catamarca, Mendoza, Salta, San Juan, Tucumán), Chile: Arica y Parinacota, Coquimbo, O’Higgins, Santiago, Tarapacá ................................................................................................ U. tessariae

- Antennal segment VI processus terminalis 4.0‾5.3 times antennal segment VI base. First tarsal segments always with 5 setae. Siphunculi brown to dark-brown. Reddish-brown, brown or blackish brown when alive............................ 17 17 Ultimate rostral segment 0.8‾1.0 times HT2, which is 0.14‾ 0.17 mm. Setae on antennal segment III 30 ‾40 µm. Cauda usually 0.30‾ 0.38 mm (down to 0.25 on some alatae). Brown in life. On Eupatorium . Argentina: Córdoba, La Rioja, Mendoza, Salta, Tucumán ................................................................................... U. garnicai

- Ultimate rostral segment 1.0‾1.2 times hind tarsi second segment, which is 0.12‾ 0.15 mm. Setae on antennal segment III 17 ‾30 µm. Cauda 0.24‾ 0.35 mm. Red-brown, dark-brown or blackish-brown in life. On species of Baccharis, Bidens and Conyza and on Perthenium hysterophorus. Brazil; Argentina: Catamarca, Córdoba, Entre Ríos, Jujuy, La Rioja, Mendoza, Salta, San Juan, San Luis, Tucumán; Chile: Coquimbo, Santiago ....................................... U. tucumani

18 Siphunculi (0.35‾ 0.55 mm) shorter than 1.1 times cauda, which is conspicuously darker than coxae. [Ultimate rostral segment shorter than antennal segment VI base. Abdominal segments 2 to 4 with marginal papillae.] Green in life. On Baccharis and dubiously on Grindelia. Chile: La Araucanía, Los Lagos, Ñuble, Santiago ............................. U. brevisiphon

- Siphunculi longer than 1.1 times cauda; if they are 1.1 times cauda, this is yellowish, similar to coxae and contrasting with siphunculi and distal part of femora....................................................................... 19

19 Cauda yellow, contrasting with dark-brown to black siphunculi and distal 1/4‾1/2 of hind femora. [Siphunculi 1.1‾1.5 times cauda, which is 0.40‾ 0.75 mm. Ultimate rostral segment longer than both antennal segment VI base and hind tarsi second segment]............................................................................................. 20

- Cauda light-brown or darker, and not contrasting with siphunculi or distal portion of hind femora.................... 21

20 Proximal 1/3‾1/2 portion of siphunculi clearly paler than rest. Bright orange-red in life. On Rudbeckia . Nearctic introduced species. Brazil............................................................................. U. rudbeckiae

- Siphunculi wholly dark-brown, exceptionally paler at extreme base. Dull red to red-brown in life. On species of several genera of Asteraceae . The nominotypical subspecies is Nearctic; subspecies lizerianum has been recorded from Bolivia, Brazil, Colombia, Peru, Venezuela; Argentina: Buenos Aires, Chubut, Córdoba, Corrientes, Entre Ríos, Jujuy, Mendoza, Río Negro, Salta, San Luis, Santa Fe, Tucumán; Chile: Arica y Parinacota, Aysén, Biobío, Coquimbo, La Araucanía, Los Lagos, Magallanes, Maule, Ñuble, O’Higgins, Santiago, Valparaíso .............................................. U. ambrosiae

21 Ultimate rostral segment (0.16‾ 0.20 mm) 1.1‾1.3 times hind tarsi second segment............................... 22

- Ultimate rostral segment (0.12‾ 0.18 mm) 0.8‾1.1 times hind tarsi second segment............................... 23

22 Antennal segment VI processus terminalis at most 5.9 times antennal segment VI base, usually shorter than 5.4 times in apterae (exceptionally up to 6.1 times in some alatae). Antennal segments I and II as dark as the most part of antennal flagellum. Setiferous and postsiphuncular sclerites present and well pigmented. Antennal segment III with 18‾29 and 24‾39 secondary sensoria in apterae and alatae respectively. On Baccharis. Chile: La Araucanía, Los Lagos ...... U. pseudomuermosum

- Antennal segment VI processus terminalis at least 6.0 times antennal segment VI base. Antennal segments I and II paler than the most part of the antennal flagellum. Dorsal abdominal sclerites usually absent, if present then pale. Antennal segment III with 7‾19 and 14‾36 secondary sensoria in apterae and alatae, respectively. Brown in life. On Baccharis and Eupatorium condolleanum . Argentina: Entre Ríos; Chile: Coquimbo, Santiago ......................................... U. chilense

23 Antennal segment III of apterae with 15‾35 secondary sensoria distributed over nearly the whole length of segment. Green in life. [In apterae, siphunculi brown to dark-brown always on whole length and scaly or wrinkly basally to reticulation (pigmented specimens), or yellowish-brown to brown with nearly smooth middle portion (pale specimens); cephalic dorsum, antennal segments I and II corrugated, and more proximal portion antennal segment III tenuously wrinkly in well pigmented specimens and not as evident in pale ones; setiferous sclerites present in darkest specimens but the marginal ones do not coalesce to form patches . In alatae, antennal segment III with (19)28‾35 secondary sensoria; and marginal patches present, but usually small and poorly pigmented]. On species of several composite genera: Baccharis, Buva, Conyza, Erigeron, Hysterionica and Tanacetum . Brazil, Peru; Argentina: Buenos Aires, Chubut, Córdoba, Entre Ríos, Jujuy, Mendoza, Río Negro, Salta, San Luis, Tucumán; Chile: La Araucanía, Los Lagos, Maule, Ñuble.................................... U. bereticum

- Antennal segment III of apterae with 7‾22(29) secondary sensoria extended at most on 2/3 of its length. Brown or reddishbrown in life....................................................................................... 23

24 In apterae, antennal segment III with 12‾22(29) secondary sensoria extended at most on 2/3 of its length; siphunculi brown to dark-brown but often with a paler proximal portion, darker than cauda, nearly smooth or corrugated on the proximal portion and tenuously scaly on the middle portion; dorsum of the head, antennal segments I and II corrugated and more proximal portion of antennal segment III wrinkly; and setiferous sclerites usually present on dorsum of thorax and abdomen, sometimes the marginal ones coalescent to form small patches. In alatae antennal segment III with (20)26‾36 secondary sensoria; setiferous sclerites present and marginal patches present and well pigmented. Reddish-brown in life. On Baccharis juncea. Argentina: Mendoza)............................................................................... U. mendocinum

- In apterae, antennal segment III with 7‾15 secondary sensoria restricted to proximal 1/2 of the segment; siphunculi yellow to dark-brown, and always on whole length scaly or wrinkly basal to the reticulation; dorsum of the head and antennal segments I to III more-or-less smooth; setiferous sclerites usually present, but marginal coalescent patches absent. In alatae, antennal segment III with 11‾24 secondary sensoria; and marginal patches present, but usually small and poorly pigmented. Brown in life. [On several species of Baccharis and also on species of Buva, Erigeron, Hysterionica, Proustia and Taraxacum . Bolivia; Argentina: Catamarca, Córdoba, Mendoza, Neuquén, Río Negro, Salta, San Juan Santiago del Estero; Chile: Coquimbo, Biobío, Maule, Ñuble, Valparaíso ................................................................ U. macolai

Figures

FIGURE 1. Uroleucon nahuelhuapense Nieto Nafría & von Dohlen, sp. n. Apterous viviparous female. A, habitus. B, Antennal segments II and III. C, Antennal segment VI and very end of antennal segment V. D, Tarsus and very end of tibia of hind leg. E, Siphunculus. F, Apical part of siphunculus. G, cauda and anal plate. A–C, F and G, holotype; D and E, a paratype, specimen number 5.

FIGURE 2. Unrooted neighbor-joining dendrogram of selected South American native Uroleucon species (see Table 1) and Northern Hemisphere Uroleucon species, derived from Tamura-Nei distances calculated from mitochondrial tRNAleu-COII sequences (Table 3).