Aphis (Aphis) conspicua Nieto Nafría & Mier Durante, 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 : 158-159

Aphis (Aphis) conspicua Nieto Nafría & Mier Durante , sp. n.

( Fig. 2 ; Table 1 )

Types. Holotype. Apterous viviparous female (measured specimen ARG-448 number 16, mounted with two paratypes) : ARGENTINA, Neuquén: Huiliches dep., Junín de los Andes (39º 54’ S, 71º 04’ W, 800 m), 23-January-2000, on Baccharis salicifolia, Universidad de León collection . Paratypes: 214 apterous viviparous females [apt] and 1 alate viviparous female [al], Natural History Museum, London and Universidad de León collections . ARGENTINA, Mendoza: Malargüe dep., Arroyo Las Minas (35º 27’ S, 69º 50’ W, 1960 m), 4-February-2000, on Baccharis salicifolia, Ortego leg. (62 apt) ; Malargüe dep., La Colorada (35º 30’ S, 69º 49’ W, 1810 m), 4-February-2000, on Baccharis salicifolia (3 apt) ; Malargüe dep., Puesto Los Palacios (35º 28’ S, 69º 49’ W, 1885 m), 28-November-2012, on B. salicifolia, Arneodo & Ortego leg. (1 apt) . ARGENTINA, Neuquén: same data as the holotype (76 apt, 1 al) ; Minas dep., Los Carrizos (37º 03’ S, 70º 46’ W, 1150 m), 6-December-1998, on Baccharis salicifolia, Ortego leg. (33 apt) . CHILE, Maule: Talca prov., road to Paso Pehuenche at 2510 m (35º 59’ S, 70º 24’ W), 2-February-2000, on Baccharis linearis (41 apt).

Etymology. The specific epithet conspicua is an adjective in nominative singular, and is feminine to agree with the genus name Aphis , which according to the context can means: “visible”, “that is in view”, “that is seen”, and also “distinguished”, “remarkable”, “indisputable”, which is in relation to the set of characters that the viviparous females present that allows us to easily separate this species from the remaining South American Aphis species.

Descriptions. Apterous viviparous females ( Figs. 2 A-2D). From 215 specimens. When alive matt yellowish grey to matt black. 1.125 –1.849 mm long. Metric and meristic features in Table 1 . Head, including clypeus and mandibular and maxillar lames and rostrum brown, sometimes with an irregular epicraneal line. Frons smoothly sinuate. Antennae usually six-segmented. Antennal segments I, II, V, VI and sometimes IV and a part of III as pigmented as cephalic dorsum, other parts of antennae brownish yellow. Antennal segments I, II and most of III smooth, IV with small transversal striae and V and VI imbricated. Rostrum reaches nearly to the hind leg coxae. Ultimate rostral segment darker than proximal ones and carrying 2 accessory setae. Legs well pigmented, usually brown like cephalic dorsum except for a small proximal portion of femora, and ¾ proximal of tibiae that are brownish yellow. Tarsal chaetotaxy formula 3.3.2. Prothorax with very extensive sclerotisation, although never complete, rough and variably pigmented; mesothorax with marginal patches and a complete or fragmented transversal band, both two reticulated and well pigmented; metathorax with marginal patches also pigmented and reticulated. Dorsal abdominal sclerotisation is variable; in the most sclerotized and darkest specimens segments 1 to 5 have spinopleural bands that are very irregular in shape, frequently interrupted, brown and reticulated, plus small marginal sclerites that carry the tubercles, and segments 6, 8 and occasionally 7 have small setiferous sclerites. In less sclerotized specimens only a few small and dispersed spinal or pleural sclerites are present on presiphuncular segments. Intersegmental and spiracular sclerites on thorax and abdomen dark brown. Marginal tubercles very broad and low, on prothorax and on abdominal segments 1 and 7, as is usual in Aphis , and also on all intermediate abdominal segments (rarely lacking on 6), frequently also on metathorax and sometimes on mesothorax; the diameter of those on prothorax as long as or longer than the eye diameter, those on the thoracic segments and on abdominal segments 5 to 7 are smaller than others but their maximum diameter is as long as or longer than the nearest seta. Siphunculi cylindrical, sometimes basally enlarged, with small flange, homogeneously as dark as or darker than the abdominal dorsum and imbricated. Genital and anal plates dark-brown. Cauda long-triangular, sometimes with a very slight proximal constriction. Setae in general very long, very slender and pointed.

Alate viviparous females ( Figs. 2 E-2F). From 1 specimen. Approximately 1.6 mm long, (the specimen is broken). Very similar to apterous viviparous females, with the following differences in addition to different thoracic configuration: (1) antennae more homogeneously dark; (2) segment III rough and with 6 to 7 secondary sensoria, aligned over the entire length; (3) segment IV sometimes with 1 secondary sensorium, (4) marginal tubercles on prothorax and abdominal segments 1 to 7 protruding, cylindrical and flat domed; (5) much poorer dorso-abdominal sclerotisation. Metric and meristic features in Table 1 .

Bionomics. Specimens of A. conspicua sp. n. live on the stems of plants of Baccharis salicifolia (Ruiz & Pav.) Pers. and B. linearis (Ruiz & Pav.) Pers. in compact groups. Alate females seem to be very rare. Sexual forms are not known so we are uncertain of their life cycle, but the species may be holocyclic.

Distribution. The area of distribution recorded for Aphis conspicua is smaller than that of the other two species described here; the two localities placed at the ends of this area are 520 km from each other in a straight line, nevertheless it is possible that its range is broader and overlaps with the area of distribution of its host plants, Baccharis salicifolia is known in Argentina from the northern border to Santa Cruz and in a large part of Chile to Aysén, and B. linearis is known in the Chilean Andes slopes from Antofagasta to Aysén and in Argentina from San Juan to Chubut.

Taxonomic discussion. Aphis conspicua sp. n. can be differentiated from species of “group 5” in the key to apterous viviparous females of Aphidina species recorded in Argentina and Chile by Nieto Nafría et al. (in press) (see “taxonomic discussion” of A. fuentesi for the distribution and size of its marginal tubercles). Among these species, only A. papillosa has very large marginal tubercles, but these tubercles are absent on meso- and metathorax, usually absent on abdominal segment 6 (only 16% of specimens have 1 papilla at least [Mier Durante et al., 2003]) and can be absent on one side of abdominal segment 5. In addition, both species can be separated by the length of siphunculi 0.9–1.4 times cauda and 0.11–0.27 mm in A. conspicua versus 0.4–0.9 times cauda and 0.07–0.16 mm in A. papillosa , and also by the length of setae, which are longer in A. conspicua , for example respectively in A. papillosa and A. conspicua , the setae on the vertex are 10–33 μm and 37–55 μm, on antennal segment III are 10–25 μm and 22–50 μm and on spinal zone of abdominal segments 2 or 3 are 10–31 μm and 35–57 μm.

Differences between the various Aphis species that live on Baccharis species are shown in the identification key to apterous viviparous females at the end of the “taxonomic discussion” section of Aphis fuentesi .

Figures

FIGURE 2. Aphis conspicua Nieto Nafría & Mier Durante, sp. n. A–D, apterous viviparous female; A, specimen with intermediate dorsal sclerotisation; B, dorso-thoracic reticulation; C, marginal tubercles on metathorax (small one placed partially on the pigmented sclerite) and abdominal segments 1, 2 and 3; D, dorso-abdominal reticulation. E–F, Alate viviparous females; E, head plus a part of prothorax, and a part of metathorax plus abdomen; F, antennal segment III. The scales vary according to specimens or parts photographed; see measurements in Table 1.