Delfinoia, a new South American aphid genus (Hemiptera, Aphididae, Macrosiphini) on Cayaponia (Cucurbitaceae)

Abstract The genus Delfinoia Nieto Nafría & Mier Durante gen. n. is established, and Utamphorophora peruviana (Essig), originally Amphorophora peruviana and currently Delfinoia peruviana comb. n., is designated species type of the genus. The synonymy between this species and Wahlgreniella australis Delfino syn. n. is established. Apterous and alate viviparous females of D. peruviana are redescribed; the male is also described. The species is currently known from Peru and Argentina; a plant of the genus Cayaponia (Cucurbitaceae) is the only identified host.

Utamphorophora peruviana was described by Essig (1953) as Amphorophora peruviana from three alate and four apterous viviparous females, although he wrote three alatae and five apterae, which were "obtained by beating onto a canvas sheet" in Rio Pampas (Peru). This capture procedure allows us to speculate whether the host plant was a tree, or perhaps a shrub, but it also could be a vine climbing on a tree. The species was subsequently transferred to Utamphorophora Knowlton, 1946 by Eastop (in Remaudière andRemaudière 1997) without any explanation. Favret (2016) maintains this taxonomic position, which is nevertheless controversial because the ultimate rostral segment of the viviparous females of this species carries many accessory setae, as Essig (1953) illustrated (Fig. 1), while it has only two accessory setae in the viviparous females of the other currently known Utamphorophora species. The species is not included in the identification keys by Blackman and Eastop (2016) because its host plant was unknown.
Wahlgreniella australis was described (Delfino, 1981) from 11 alate and 16 apterous viviparous females collected from Cayaponia sp. in Cordoba (Argentina). Cayaponia (Cucurbitaceae) includes nearly 60 species, which characteristically are vine plants, and are spread over diverse territories of America from Oklahoma (USA) to Uruguay; several species have been recorded from Argentina, and three from Cordoba province, (Duchen and Renner 2010;Pozner 2016). The novelty of the aphid species and implicitly its generic adscription had been endorsed by D. Hille Ris Lambers (see Delfino 1981: 185). The species was maintained in Wahlgreniella Hille Ris Lambers, 1949 by Remaudière and Remaudière (1997), Blackman and Eastop (2016) and Favret (2016). Nevertheless this generic adscription is also debatable because the species exhibits some morphological characteristics that are different to those in other Wahlgreniella species; for example the triangular (rather than digitiform) cauda and the relatively weakly developed frontolateral tubercles. In addition all other Wahlgreniella species are North American or European in origin, and their host plants are species of Rosa and of Ericaceae in migrant species, or species of either Rosa or Ericaceae in monoecious species (Blackman and Eastop, 2016).
Comparing the descriptions of the two species, and Essig's drawings of U. peruviana ( Fig. 1) with the prepared specimens of W. australis conserved in the collection of the Muséum national d'Histoire naturelle in Paris (France) (Fig. 2C, D), some similarities between them appear: shape of frons (divergent frontolateral tubercles present), length of antennal segment VI terminal process (near six times antennal segment VI base), shape of siphunculi (swollen, with long pedunculate proximal portion), cuticular ornamentation of siphunculi (absent in swollen portion), shape of cauda (triangular), setae of penultimate and ultimate rostral segments (abundant), secondary sensoria (only present on antennal segment III of alate viviparous females), and wing veins (cubitals dusky bordered).
The aim of this work is to contribute to knowledge of South American native aphid species by (1) increasing the known data of Utamphorophora peruviana from the re-examination of its types, (2) increasing the known data for viviparous females of Wahlgreniella australis and describing its male, and (3) reassessing the taxonomic position of these two nominal species.  (Essig, 1953). (Note: contrary to the legend, the antennal segment III attributed to an apterous viviparous female must be from an alate female, as Essig described the aptera (on page 135) as being without secondary sensoria).

Materials and methods
Studied specimens of Utamphorophora peruviana (Essig) Measurements were taken according to Nieto Nafría and Mier Durante (1998) with an ocular micrometer mounted on a light-field microscope. Microphotographs were taken with a Nikon set: SMZ1500 stereoscopic microscope with oblique coherent light, DXM1200F digital camera, and NIS-Elements F version 3.22 software (for Fig. 2), and with a smartphone through the eyepiece of a microscope Olympus CX41 (for Fig. 4). Drawings (Fig. 3) were made with the help of a camera lucida attached to the microscope.

Results and discussions
The qualitative features of the studied viviparous females of U. peruviana (Essig) and W. australis Delfino are identical (Fig. 2) and the metric and meristic features are very similar (Table 1). Consequently, we propose that Wahlgreniella australis Delfino, 1981 syn. n. is a junior synonym of Utamphorophora peruviana (Essig, 1953).
Additionally several qualitative features, particularly the absence of cilia in the relatively thick edge of the primary sensoria, allow us to separate this species from species in other genera of Macrosiphini with similar characteristics, establishing a new genus, which is named Delfinoia.
Type species. Amphorophora peruviana Essig, 1953. Taxonomic discussion. Ten genera and one subgenus of Macrosiphini known in the Americas have more or less developed and divergent or parallel frontolateral tubercles, long antennae and elongate swollen siphunculi (characters 2, 3 and 4); they are Amphorophora Buckton, 1876, Delphiniobium Mordvilko, 1914, Gibbomyzus Nieto Nafría, Pérez Hidalgo, Martínez-Torres & Villalobos Muller, 2013, Glabromyzus Richards, 1960, Hyperomyzus Börner, 1933, Illinoia Wilson, 1910, Rhopalomyzus Mordvilko, 1921and Ucrimyzus Mier Durante & Pérez Hidalgo, 2013, Utamphorophora and Wahlgreniella, and the subgenus Picturaphis Blanchard, 1922 which is currently included in genus Microparsus Patch, 1909. Feature 1 is the most distinctive character of the new genus, and is very exceptional in Macrosiphini, and features 5 to 13 in combination help to separate the new genus from any of the above mentioned genera, although they are present in some of them.
The novelty of the genus could be assured with complete certainty by the analysis of some genetic marker, which cannot be carried out at present because all the known material of the species is mounted on microscopic slides.
Etymology. The name Delfinoia is in honour of Dr. Miguel Ángel Delfino (retired professor of entomology, University of Cordoba (Argentina), aphidologist and good friend for decades), who was the author of W. australis. (Essig, 1953)

Description. Apterous viviparous females (redescription, from 30 studied specimens [see "Materials and methods"] and original descriptions of both nominal species).
Colour unknown when alive, possibly green or light green, and perhaps, from Essig's drawing, with two small dark spots on each side of several abdominal segments, brown cauda and dark brown or blackish brown siphunculi. When mounted variably light yellow, with head, including antennae and rostrum, legs, siphunculi, anal plate and cauda more or less pigmented (see below). Quantitative characters are in Table 1. Head. Brownish yellow. Frons sinuated, with broadly divergent and moderately developed frontolateral tubercles and low frontomedial tubercle. Dorsum smooth and ventrum with stretch marks. Setae of first and second dorsal row (each with two setae) and internal setae of third dorsal row (with four setae) similar in length to each other; external setae of third row approximately half as long as the other six. These eight dorsocephalic setae, the frontolateral apical setae and the three ventrolateral setae on each side (near the margins of the antennal alveoli) have truncate apices; other ventral setae, including those on clypeus and on mandibular and maxillar laminae, are pointed. Antennal segment I slightly pigmented and mostly smooth, with its inner side somewhat darker and gently scabrous; segment II also slightly pigmented, dorsally smooth and ventrally scabrous. Antennal segment III also pale, with a smoky apical ring, and tenuous cuticular ornamentation, which is more marked on the ventral face of its 1/5 proximal portion. Its subarticular constriction is less marked than in some other aphids; possibly the antennal flagellum has reduced mobility with respect to the pedicel as a result of this structural feature. Antennal segment IV softly imbricated and mostly pale, with smoky small proximal ring and distal portion; segment V similar to segment IV but more intensely imbricated and with a longer and more pigmented distal portion. Antennal segment VI brown and imbricated. Several setae on segment VI are pointed and longer than other antennal setae, which are similar in shape and size to dorsocephalic ones. Secondary sensoria absent. Primary sensoria on antennal segments V and VI with thick, sclerotic and non-ciliate margins. Satellite sensoria  (Essig). A-F apterous viviparous females G alate viviparous female A frontal edge B dorsocephalic setae, third row, the shorter is the external one C pre-ultimate and ultimate rostral segments D spiracular abdominal plate and aperture E siphunculus F cauda G antennal segment III. grouped ventrad to the primary sensorium. Rostrum extends back to slightly beyond hind coxae. Penultimate and ultimate rostral segments similar in length and colour (light brown) and bearing many robust, rigid and pointed setae. Thorax. Paler than head and generally devoid of marked cuticular ornamentation. Spiracular sclerites rugose and unpigmented, spiracular apertures circular or subcircular. Marginal papillae on prothorax if present are small, flat and unpigmented. Both dorsal and ventral setae similar in shape and size to those on anterior abdominal segments. Tarsi and apex of tibiae pale brown, rest of legs brownish yellow. Setae on femora and most of those on tibiae short and with truncate apices; setae on coxae (which are longer than others), trochanters and tarsi pointed, as also are dorsoapical tibial setae. First segments of tarsi with three setae. Abdomen. In general paler than head. Spiracular sclerites and apertures similar to those on thorax. Intersegmental sclerites inconspicuous. Small presiphuncular sclerites small, postsiphuncular sclerites relatively wide, and a narrow transverse stripe on segment VIII; all of these sclerites spinuled and pale yellow. Dorsal setae short and with truncate apices, except those on abdominal segment VIII, which are pointed. Ventral setae pointed. One specimen (paratype) has one marginal tubercle on abdominal segment IV, small and pale. Siphunculi light brown, swollen over distal half of length, smooth or nearly smooth for most of length, and with three or four complete or incomplete circular lines below the flange, which is protruding and relatively thick. Genital plate very pale; anal plate with similar pigmentation to cauda, which is triangular with blunt apex. Setae on these plates and cauda pointed.
Alate viviparous females (redescription, from 12 studied specimens [see "Materials and methods" section] and from original descriptions of both nominal species). Fig. 2B, D.
Colour unknown when alive, possibly with dark brown or black head and thorax, including antennae and legs, and green abdomen with dark brown lateral spots, cauda and siphunculi. Quantitative characters are in Table 1; qualitative characters like those of apterae are not mentioned. Head. Brown with darker areola around each ocellus. Dorsum with tenuous ornamentation. Frontolateral tubercles very low and frontomedial tubercle inconspicuous. Antennae homogeneously brown. Antennal segment III with secondary sensoria, which are similar in shape to the primary ones and variable in size, more-or-less aligned over almost the entire length. Thorax. Legs brown, with paler coxae, trochanters and proximal part of femora. Fore wings with veins well-marked and the cubital veins dark-bordered; hind wings veins also well-marked but not bor- dered. Abdomen. Pale in general. Sclerites variably pigmented, sometimes as pale as the rest of the abdominal cuticle. Intersegmental sclerites smooth. Marginal sclerites on segments I -VII spinuled, the postsiphuncular sclerites being wider than the others. Setiferous spinal and pleural sclerites present on segment VIII and sometimes on segments VI and VII, all of them spinuled and usually pale or very pale. One specimen (holotype) has four small, ill-defined and pale marginal tubercles on abdominal segments II, III (on both sides) and IV; another specimen (paratype) also has similar tubercles on one side of abdominal segments III and IV.
Males (from one specimen, see "Materials and methods" section). Fig. 2E-F. Winged; similar to alate viviparous females in general aspect, pattern of sclerotisation, extent of pigmentation and cuticular ornamentation. Colour when alive unknown. Secondary sensoria present on antennal segments III, IV and V. Hind wings have a single oblique vein, which could well be an anomaly, although the presence of an identical anomaly in both wings is strange. Two small pale abdominal marginal tubercles present. Parameres broad, curved back, very dark brown and provided with many, rigid, pointed and relatively long hairs. Quantitative characters are in Table 1.
Biology. It is certain that Delfinoia peruviana feeds on plants of one or more species of Cayaponia in Argentina, and perhaps also in Peru (see "Introduction"). The species has been also caught on a cruciferous plant in Cordoba (Argentina). The collector of those specimens, L. Bahamondes, was an experienced (but now deceased) entomologist and a connoisseur of Argentinean flora, so one can be certain that the specimens were collected on a plant of family Brassicaceae, but it is also conceivable that the specimens collected had fallen from some vine of the genus Cayaponia.
Distribution. The species is currently known in two localities (one in Peru and the other in Argentina) that are 2,200 kilometers distant from each other. Possibly the species can be found in much of northern Argentina, southern Peru and also in eastern Bolivia and southwestern Brazil.