Aphis (Aphis) fuentesi Nieto Nafría & Ortego, 2019

Nafría, Juan Manuel Nieto, Ortego, Jaime, Brown, Paul A., López Ciruelos, Sara I. & Durante, M. Pilar Mier, 2019, Aphis (Hemiptera, Aphididae) species living on Baccharis (Asteraceae) in southern South America, with description of three new species, Zootaxa 4656 (1), pp. 153-167 : 161-165

Aphis (Aphis) fuentesi Nieto Nafría & Ortego , sp. n.

( Fig. 3 ; Table 2 )

Types. Holotype: apterous viviparous female (specimen ARG-392 number 2, mounted with three paratypes) : AR- GENTINA, Chubut, Cushamen dep., Epuyén (42º 12’ S, 71º 23’ W, 370 m), 19-January-2000, on Baccharis linearis, Universidad de León collection . Paratypes: 940 apterous viviparous females [apt], 51 alate viviparous females [al], 34 oviparous females [ov] and 8 males [m], Natural History Museum, London and Universidad de León collections . ARGENTINA, Chubut: same data as the holotype (50 apt, 18 al) . ARGENTINA, Neuquén: Huiliches dep., Junín de los Andes (39º 54’ S, 71º 04 ‘W, 800 m) 23-January-2000, on Baccharis magellanica (104 apt, 1 al) ; Lácar dep., San Martín de los Andes (40º 10’ S, 71º 21’ W, 750m), 22-January-2000, on Baccharis rhomboidalis (58 apt) ; same locality and date, on Baccharis sp. (73 apt, 1 al) ; Los Lagos dep., Lago Escondido (40º 27’ S, 71º 34’ W, 980m), 10-January-2019, on Baccharis concava, Ortego leg. (42 apt, 26 al) ; Los Lagos dep., Puerto Huemul (41º 01’ S, 71º 20’ W, 860m), 21-January-2000, on Baccharis . sp. (117 apt, 2 al) . ARGENTINA, Río Negro: Bariloche dep., San Carlos de Bariloche (41º 08’ S, 71º 14’ W, 870 m), 18-April-2012, on Baccharis rhomboidalis, Ortego leg. (1 apt, 34 ov, 8 m) ; 10-January-2019, on Baccharis linearis, Ortego leg. (24 apt) ; Pilcaniyeu dep., Dina Huapi (41º 04’ S, 71º 07’ W, 500 m), 19-January-2000, on Baccharis sp. (103 apt, 3 al) . CHILE, Maule: Talca prov., road to Paso Pehuenche at 1160 m (35º 51’ S, 70º 41’ W), 2-February-2000, on Baccharis sp. (148 apt) ; Talca prov., road to Paso Pehuenche at 1210 m (35º 51’ S, 70º 41’ W), 30-January-2016, on Baccharis concava (140 apt) and on Baccharis linearis (73 apt).

Etymology. The specific epithet fuentesi is dedicated to our colleague and friend Eduardo Fuentes Contreras (University of Talca), who has studied Chilean aphids from several points of view, see acknowledgements section.

Descriptions. Apterous viviparous females ( Figs. 3 A-3D). From 941 specimens. When alive matt dark green to matt black. 1.00– 1.64 mm long; other metric and meristic features in Table 2 . Head, including clypeus and mandibular and maxillar lames and rostrum brown, sometimes with an incomplete epicraneal line. Frons more or less sinuate. Antennae six- or five-segmented, unrelated to body length or sample provenance. Antennal segments I, II, VI and a distal portion of V more-or-less as pigmented as cephalic dorsum; proximal part of antennal segment V and segments III and IV in six-segmented antennae or III + IV in five-segmented antennae brownish yellow to light brown. Antennal segments I, II and ventral side of III smooth, dorsal side of III weakly imbricated, segment IV with small imbrications or transversal striae, segments V and VI imbricated. Rostrum exceeds hind leg coxae, brownish yellow and progressively darkened. Ultimate rostral segment with straight edges and with 2 accessory setae. Coxae, most of femora, distal portion of tibiae, and tarsi brown, sometimes as cephalic dorsum; other parts of legs brownish yellow. Tarsal chaetotaxy formula 3.3.2. Prothorax with sclerotized, reticulated and variably pigmented sclerites or patches, which do not meet together to form transversal bands; mesothorax with marginal patch and a transverse complete or fragmented transversal band, both two being well pigmented and reticulated; metathorax with marginal sclerites or patch, pigmented and reticulated. Dorso-abdominal sclerotisation and pigmentation very variable, unrelated to body length, host plant, or sample provenance; in most sclerotized and dark specimens: segments 1 to 5 with a spinopleural irregular patch, or only 3 to 5 and then segments 1, 2 with irregular spinopleural bands, segment 6 also with a transversal band, all with small marginal sclerites that support the tubercles and all brown and reticulat- ed, segment 7 with setiferous sclerites and segment 8 with a narrow transversal band; in less sclerotized specimens segments 1 to 7 without segmental sclerites and segment 8 with setiferous sclerites. Intersegmental and spiracular sclerites darker than segmental sclerites when they are present. Marginal tubercles on prothorax and abdominal segments 1 to 7 (may be lacking on 5 or 6), always wide and, those on prothorax shorter than eye length, those on abdominal segments 1 to 4 with diameter usually shorter than the marginal setae length and those on segments 5 to 7 smaller than others. Siphunculi very small —shorter than the basal width of cauda—, cylindrical, as brown as cauda and cephalic dorsum, with small flange and with imbrication, which is more abundant and thick on the ventral face than on the dorsal face. Genital and anal plates brown. Cauda with two distinctive parts, the proximal is large and the distal is narrow and more or less triangular or subcylindrical. Setae in general pointed, relatively robust and pale.

Alate viviparous females ( Figs. 3 F-3G). From 51 specimens. 1.18–1.83 mm long. Very similar qualitatively to apterous viviparous females, differing from them, in addition to the configuration of the thorax, by the following features: (1) antennae more homogeneously dark, only the most basal portion of segment III is pale brown; (2) antennal segment III rougher and with 4–13 secondary sensoria, aligned over distal 2/3 or 3/4; (3) antennal segment IV usually with secondary sensoria, 1–3 in number and smaller than those on III; (4) marginal tubercles taller; (5) abdominal segments 1 to 6 without spinal or pleural sclerites and with relatively wider marginal sclerites, including pre- and postsiphuncular ones; (6) setiferous sclerites on segment 7 sometimes coalescent to form a bar. Metric and meristic features in Table 2 .

Oviparous females, apterous ( Fig. 3H ). From 34 specimens. 1.29–1.60 mm long. Very similar qualitatively to apterous viviparous females, with the following differences, of which those marked with an asterisk are specific to oviparae: (1*) body larger, but without the distending and lengthening of the postsiphuncular segments present in some species of Aphis ; (2) antennae homogenously pigmented and more or less as dark as cephalic dorsum; (3) rostrum not always exceeding hind coxae; (4) legs darker, especially hind legs, which are brown to dark brown, except a very small proximal portion of femur; (5*) hind tibiae homogeneously thickened, but not much thicker than tibiae of front and middle legs, and carrying 16 to 47 scent plates; (6) absence of abdominal continuous spinopleural patch on abdominal presiphuncular segments; (7) abdominal segments 7 and 8 only with some small setiferous sclerites; (8*) abdominal segment 8 with many more setae; (9*) genital plate with a pale middle portion and carrying many more discal setae; (10) cauda triangular. Metric and meristic features in Table 2 .

Males, apterae ( Fig. 3I ). From 8 specimens. 1.15–1.34 mm long, smaller than oviparous females. Very similar qualitatively to apterous viviparous females, with the following differences in addition to presence of copulatory apparatus, with conical, robust and dark brown parameres, and secondary sensoria on antennal segments III, IV and V, respectively 5 to 13 (exceptionally 1), 4 to 8 (exceptionally 1) and 2 to 6: (1) antennae and legs darker; (2) paired spinopleural patches present from mesothorax to abdominal segment 6, many of them contacting or merging with the neighbours; (3) abdominal segment 7 with a transversal pigmented band; (4) cauda triangular to irregular pentagonal (two sides in contact with the anterior side of the pentagon have greater length than the rest). Metric and meristic features in Table 2 .

Bionomics. Specimens of A. conspicua sp. n. live on the stems of plants of several species of Baccharis in compact groups, the alate viviparae are very infrequent in summer. Baccharis concava (Ruiz & Pav.) Pers. , B. linearis (Ruiz & Pav.) Pers. , B. magellanica (Lam.) Pers. , and B. rhomboidalis Remy has been identified as the host plants for this aphid.

The species is monoecious holocylic; oviparous and males were collected at medium altitude (870 m) in a relatively early date in autumn. Hind tibiae of oviparae are not especially thickened and carry a small quantity of scent plates, which correlates with the apterism of males.

Distribution. Collects of A. fuentesi sp. n. have been made in the Argentinean Andean provinces of Neuquén, Río Negro and Chubut or to Chilean region of Maule, on the slopes of Paso Pehuenche. The furthest from each other are about 710 km in straight line. It is possible that the species is widely distributed, with a range that could correspond with those of their host species, both widely spread in Chile and in several of the Andean provinces of Argentina.

Taxonomic discussion. The features of Aphis fuentesi sp. n. place it in the species “group 5” in the key to apterous viviparous females of the Aphidina species recorded in Argentina and Chile by Nieto Nafría et al. (in press), which are characterized by: (a) siphunculi on abdominal segment 5, (b) clypeus not enlarged, (c) stridulatory apparatus absent, (d) marginal tubercles present on both abdominal segments 1 and 7, (e) genital plate with posterior setae, (f) antennal segment III without secondary sensoria, (g) marginal tubercles present in several intermediate abdominal segments (2 to 6). In this species group were included: Aphis carrilloi Ortego, Mier Durante & Nieto Nafría, 2013 , A. coridifoliae Mier Durante & Ortego, 1999 , A. fabae Scopoli, 1763 (in part), A. malalhuina Mier Durante, Nieto Nafría & Ortego, 1999 , A. mulini Hille Ris Lambers, 1974 , A. mulinicola Hille Ris Lambers, 1974 , A. papillosa Mier Durante, Nieto Nafría & Ortego, 2003 , A. pomi De Geer, 1773 , A. pseudopulchella Blanchard, 1944 , A. rumicis De Geer, 1773 (in part), A. sambuci Linnaeus, 1758 , A. schinivora Ortego, Nieto Nafría & Mier Durante, 2007 , A. senecionicoides Blanchard, 1944 , A. solanella Theobald, 1914 (in part), A. tehuelchis Nieto Nafría y López Ciruelos, 2016 and A. zapalina Mier Durante & Ortego, 2016 .

Aphis fuentesi sp. n. can be differentiated from most of these species by its small siphunculi, which are shorter than the basal width of cauda; only A. malalhuina and A. schinivora also have small siphunculi. A. malalhuina and A. fuentesi can be easily separated from one another by the ratio “length of siphunculi / basal width of siphunculi”, which is less than 1 in A. malalhuina and greater than 1 in A. fuentesi . In addition A. malalhuina is monoecious holocyclic with winged males on Senecio species whilst A. fuentesi is monoecious holocyclic with apterous males on Baccharis species.

The ranges of the quantitative characters of A. fuentesi and A. schinivora overlap to a greater or lesser extent and having measured a significant number of specimens only some of them are useful in their separation (see Table 3 ). In addition, a useful discriminant feature is the relationship between the diameter of the marginal tubercle on abdominal segment 7 and the largest diameter of stigmatic sclerite 7, which is less than 1 in A. schinivora and usually greater than 1 in A. fuentesi , as well as the relationship between that tubercular diameter and the length of the marginal seta of the abdominal segment 7, which is conspicuously less than 1 in A. schinivora and equal to 1 in A. fuentesi . Conversely, apterous viviparous females of both species can be easily separated when alive as those of A. schinivora are shiny black whilst those of A. fuentesi are bottle green to matt black.Additionally, two important bionomic features corroborate their separation: the host plant and the life cycle; A. schinivora is monoecious holocyclic on Schinus johnstonii with an abbreviated life cycle with sexuales being present during midsummer ( Ortego et al., 2007), whilst Aphis fuentesi is monoecious holocyclic on Baccharis species with sexuales in autumn.

Differences between the various Aphis species that live on Baccharis species are shown in the following identification key.

Figures

FIGURE 3. Aphis fuentesi Nieto Nafría & Ortego, sp. n. A–D apterous viviparous females; A, specimen moderately sclerotized; B, specimen extensively sclerotized; C, dorso-abdominal reticulation; D, siphunculus and marginal tubercles on abdominal segments 6 and 7. F–G, alate viviparous females; F, habitus; G, antennal segment III. H, oviparous female. I, male. The scales vary according to specimens or parts photographed; see measurements in Table 2.

Tables

TABLE 2. Aphis fuentesi Nieto Nafría & Ortego, sp. n., metric and meristic features. Abbreviations: apt. viv. fem. = apterous viviparous females, al. viv. fem. = alate viviparous females, ov. fem. = oviparous females; abd. = abdominal, ant. = antennal, D = subarticular width of antennal segment III, pr. term. = processus terminalis, segm. = segment, ultim. = ultimate.

	apt. viv. fem.	al. viv. fem.	ov. fem.	males
	n=121	n=16	n=10	n=7
antenna [mm]	0.530–1.040	0.710–1.130	0.623–0.725	0.550–0.613
body / antenna [times]	1.48–2.32	1.49–1.73	2.02–2.30	2.03–2.31
ant. segm. III(+IV) [mm]	0.17–0.36	//	0.21–0.26	//
ant. segm. III [mm]	0.11–0.31	0.16–0.33	0.15–0.18	0.18–0.22
ant. segm. IV [mm]	0.06–0.18	0.12–0.20	0.09–0.10	0.11–0.15
ant. segm. V [mm]	0.07–0.16	0.10–0.18	0.09–0.12	0.09–0.13
ant. segm. VI base [mm]	0.08–0.13	0.09–0.15	0.10–0.12	0.08–0.11
ant. segm. VI pr. term. [mm]	0.10–0.17	0.14–0.18	0.11–0.14	0.13–0.14
ant. segm.: III(+IV) / VI pr. term. [times]	1.4–2.4	//	1.6–1.9	//
ant. segm.: III / VI pr. term. [times]	1.1–2.2	1.1–2.0	1.1–1.4	1.4–1.6
ant. segm. VI: pr. term. / base [times]	1.0–1.9	1.1–1.8	1.1–1.4	1.2–1.6
ant. segm. III(+IV) / ultim. rostral segm. [times]	1.7–2.9	//	1.8–2.4	//
ant. segm. III / ultim. rostral segm. [times]	1.0–2.5	1.6–2.6	1.3–1.6	1.6–2.0
ant. VI segm. pr. term. / ultim. rostral segm. [times]	0.9–1.6	1.2–1.7	1.1–1.3	1.1–1.3
ant. segm. III [+IV] / cauda [times]	1.2–2.1	//	1.3–1.7	//
ant. segm. III / cauda [times]	0.9–1.6	1.6–2.0	1.1	1.5–2.0
hind femur [mm]	0.21–0.42	0.28–0.44	0.26–0.33	0.32–0.35
hind tibia [mm]	0.40–0.74	0.54–0.83	0.49–0.60	0.53–0.63
body / hind femur [times]	3.6–5.2	4.0–4.3	4.5–5.1	3.3–3.9
body / hind tibia [times]	2.1–2.8	2.0–2.3	2.6–2.8	1.8–2.6
ultim. rostral segm. [mm]	0.10–0.13	0.10–0.13	0.11–0.12	0.11–0.12
ultim. rostral segm. / ant. segm. VI base [times]	1.0–1.6	0.9–1.1	1.0–1.2	1.0–1.3
ultim. rostral segm. / its basal width [times]	2.1–3.1	2.3–3.1	1.9–2.6	1.9–2.5
hind tarsi second segm. [mm]	0.08–0.12	0.09–0.11	0.10–0.11	0.10–0.11
ultim. rostral segm. / hind tarsi second segm. [times]	1.0–1.3	1.0–1.2	1.0–1.2	1.0–1.2
siphunculus [mm]	0.05–0.12	0.06–0.10	0.06–0.10	0.05–0.06
siphunculus / its width at middle [times]	1.2–3.3	1.9–3.1	1.5–2.7	1.4–2.0
siphunculus / cauda [times]	0.4–0.6	0.4–0.7	0.4–0.6	0.4–0.6
siphunculus / cauda basal width [times]	0.4–0.9	0.5–0.9	0.5–0.7	0.4–0.6
cauda [mm]	0.12–0.21	0.10–0.17	0.13–0.17	0.11–0.13
cauda / cauda basal width [times]	1.0–1.9	1.0–1.5	1.0–1.3	0.9–1.2
SETAE on…
… ant. segm. III [num]	2–11	2–8	6	3–6
… ant. segm. III [μm]	13–38	15–33	20–30	25–28
… ant. segm. III [times D]	0.8–2.3	1.0–2.0	1.4–1.5	1.4–1.6
… head, dorsum [μm]	15–38	23–38	25–33	28–33
… head, dorsum [times D]	1.0–2.7	1.4–2.7	1.6–1.9	1.4–1.9
… hind trochanter [μm]	20–50	30–38	30–38	32–45
… hind trochanter / femoral suture [times]	0.4–1.3	0.7–0.9	0.7–0.9	0.8–1.0
… hind femur, dorsal [μm]	18–45	25–38	27–45	28–38
… hind femur, dorsal [times D]	1.1–3.0	1.7–2.6	1.5–2.6	1.4–2.1
… hind femur, ventral [μm]	20–48	25–45	33–40	30–40
… hind femur, ventral [times D]	1.4–3.3	1.8–2.8	1.6–2.4	1.7–2.3