Pyrophagus tigrinus Remes Lenicov & Varela

Marino De Remes Lenicov, A. M. & Varela, G., 2014, A new genus and species of Delphacini (Hemiptera: Fulgoroidea: Delphacidae) from Argentina, Zootaxa 3861 (2), pp. 177-184 : 179-182

Pyrophagus tigrinus Remes Lenicov & Varela , sp. n.

( Figs 1–14 )

Description. Male. Small to medium-sized, predominantly macropterous forms. Length of macropterous form: 3.0 mm in male, 3.5 mm in female; brachypterous form: 2.0 mm in male, 2.4 mm in female.

Macropterous form: Ground colour shiny dark brown; black on front and lateral parts of head including anterior 1/2 of genae, basal 1/3 of pronotum between lateral carinae, mesonotum, pleural areas of meso- and metathorax and coxae; distinctive creamy-white to yellowish on carinae of head, pronotum (except basal 1/3) and abdominal segments II (drumming organ), VII and VIII; light brown to yellowish on basal vertex, clypeus and legs, except basal segment. Wings semi-hyaline with pale brownish veins; fore wing with prominent black spot at apex of clavus along apical 1/2 of common stem of anal veins extending laterally toward commissural vein and with broad infuscate transverse stripe from inner tip of tegmina to middle of nodal line; distal veins darkened.

Head ( Figs 1, 2 ) including compound eyes 2.6x wider than vertex at base, and slightly narrower than pronotum (0.8–0.9:1); vertex subquadrate, lateral margins subparalleled, expanded laterally before and behind eye, in midline slightly longer than width at base (1,1:1); basal compartment at hind margin twice as wide as greatest length, about 0.4x length of vertex; stem of Y-shaped carina slender, delimiting shallow depressed areas on both sides; other carinae of head rounded and pronounced. Vertex evenly rounded to frons in profile, fastigium not projecting before eyes; arms of submedian carina meeting acuminately just anterior to apex. Frons in middle line longer than wide (2.2:1), widest part at level or slightly below level of ocelli, lateral margins slightly convex, submedian carina simple, broadly rounded and prominent; frontal area on each side of carinae shallowly concave. Genal carina arising from lateral edge of frontoclypeal suture and ending before base of antenna. Postclypeal disc longer than width at base (1.5:1); median and lateral carinae prominent, submedian carinae continuing onto anteclypeus. Post- and anteclypeus together little shorter than frons, in profile shallowly convex. Rostrum reaching anterior margin of metacoxa, apical segment slightly shorter than sub-apical segment (0.8:1). Antennal segments cylindrical, slender, surpassing base of postclypeus; basal segment length nearly 2x width, second segment longer than first segment (2.2:1); number and arrangement of sensory fields of pedicel: 14 in 7 rows.

Pronotum wider than head (1.1:1), in midline slightly shorter than vertex; lateral carinae distinct, curved laterally behind eye, not reaching hind margin. Mesonotum medially 4x length of pronotum, carinae distinct, straight, lateral and median carinae becoming obsolete prior to scutellum, which is lightly depressed and slightly transversally ribbed. Total length of mesoscutum disc 3x that of scutellum. Tegmina ( Fig. 3 ) rounded at apex, longer than abdomen, extending nearly 1/2 their length beyond abdomen, Sc + R branching before Cu branch, Sc cell shorter than Cu1b. Post-tibial spur ( Figs 5, 6 ) tectiform, slender, slightly shorter than basitarsus (08:1) with about 22 slender black-tipped teeth on posterior margin plus apical tooth; inner and outer margins slightly convex. Postbasitarsus as long as post-tarsal segments II and III together; spinal formula of hind leg: 5 (grouped 2 + 3) - 7 (grouped 2 + 5) - 4.

Drumming organ distinctive, with second abdominal tergite differentiated into prominent plate system readily visible externally; medially convex subquadrate central plate laterocaudally closed by sclerotized furrows; apodemes of 2nd abdominal sternite ( Fig. 4 ) long, slender, erected dorsad.

Brachypterous form: Coloration similar to macropterous form but with tegmina coriaceous, uniformly darkbrown with obscure veins; posterior margin subtruncate to slightly rounded, not surpassing 7th abdominal tergite. Hind wing reduced to scale.

Male genitalia. Genital segment ( Figs 11, 12 ) dorsally short, ventrally 3x longer than dorsally; ovate in caudal aspect, nearly twice as high as maximum width; dorsal margin V-shaped, deeply excavated to receive anal segment; in lateral view, dorsocaudal margins expanded in subquadrate lobe; ventrolaterally distinctly sinuous in profile, diafragma uniformly high and sclerotized, dorsal margin slightly medially produced in caudally protruded lobe; ventrocaudal margin trilobate, medioventral process strong, subquadrate and dorsocaudally produced, marginated with a small tooth, angular in profile. Parameres ( Fig. 7 ) short, S-shaped, dorsolaterally directed, apposed near middle, sides on apical half sinuous, apex with outer angle fairly well produced and rounded, inner angle acute with tip moderately convergent. Aedeagus ( Figs 8, 9 ) tubular, short, dorsocaudally directed, in lateral view, broader at base with small subbasal angular process arising on dorsal surface, shaft tapering, strongly reflexed ventrally in distal 1/3 forming spinelike process ventrally directed on right side; oval, subapical phallotrema on dorsal side. Connective ( Fig. 10 ) large, slightly curved cephalad, strongly compressed, dorsally fused with ventral side of aedeagus chamber. Suspensorium forming short, rectangular plate, dorsally embracing base of aedeagus. Anal segment ( Fig. 12 ) short, ringlike on caudal view, with two slightly flat ventrally directed processes on ventrocaudal angles with bases well separated and apically slightly diverging.

Measurements of macropterous forms: L.T: 3 ± 0.02; B.L: 1.8 ± 0.01; W.: 0.9; t.l.: 2.8; t.n: 20–23.

Measurements of brachypterous forms: L.T: 2.2 ± 0.02; W.: 0.9; t.l.: 1.4; t.n: 20–23.

Female. Macropterous form: Structure and color pattern similar to male but abdomen and tegmina lighter and uniformly coloured, abdominal segments sometimes with darkish marks on each side of tergites and sternites. Drumming organ inconspicuous, without major morphological alterations.

Brachypterous form: Structurally similar to brachypterous males with color pattern varying from darkish to uniformly yellowish, with intercarinal frontal region, gena and tegmina brownish with some dark spots on apical margin.

Female genitalia ( Fig. 14 ): Sternite V to VII membranous between sclerotized lateral plates. Ovipositor not surpassing anal segment; valvifers VIII ( Fig. 13 ) expanded basally in inner lobe, covering anterolaterally ca.1/3 of tergite IX; gonapophyses IX ( Fig. 14 ) slender, dorsally finely denticulated, strongly curved in basal 1/2, with ca. 20–22 small sharp teeth on dorsal margin in distal 1/2, with distal apex narrow and strongly angled; anal style moderately short.

Measurements of macropterous forms: L.T: 3.5 ± 0.03; W: 0.9; t.n: 20–23.

Measurements of brachipterous forms: L.T: 2.4 ± 0.02; W: 0.9; t.n: 20–23.

Etymology. The specific name is taken from the Greek word tigris “tiger”, in reference to the contrasting pattern of coloration. The name was emended with ‘- nus ’ to make it masculine in gender.

Remarks. This new species can be easily recognized by the following characters: prothorax and abdomen blackish with yellow-cream marks; mesonotum uniformly dark; vertex subquadrate, rounded to frons in profile; male genitalia with pygofer with medioventral process strong, diaphragm uniformly wide and caudally produced, suspensorium short and aedeagus dorsocaudally directed and ending in a strongly reflexed, spinose process; and valvifers VIII in female basally expanded.

Pyrophagus tigrinus resembles Delphacodes puella (Van Duzee, 1897) in the carination on head, color of pronotum and abdomen, and the markings and venation of fore wings, but differs from the latter in its vertex subquadrate, not projecting beyond the level of the eyes; antennae and legs longer; tegulae and mesonotum uniformly dark; and the shape of genitalia.

Distribution. Argentina (Jujuy, Salta, Tucumán, Catamarca, La Rioja, San Juan, Mendoza, San Luis, Santiago del Estero, Chaco, Misiones, Corrientes, Entre Ríos, Santa Fe, Córdoba and Buenos Aires). Brazil (Paraná and Goias).

Biology. Pyrophagus tigrinus is widely distributed in northern Argentina. It represents one of the most common species on forage Gramineae , including oat (Avena sativa L.), oat associated with rye and Melilotus sp., barley ( Hordeum vulgare L.), maize ( Zea mays L.), alepo sorghum (Sorghum halepense L.), triticale (X Triticosecale Wittmack ), wheat ( Triticum aestivum L.), Grama Rhodes (Chloris gayana Kunth), Gatton Panic ( Panicum máximum L. cv. Gatton panic), weeping lovegrass ( Eragrostis curvula (Schrad.) Ness ), and hairy crabgrass ( Digitaria sanguinalis (L.) Scop. Most of these plants have been demonstrated as host reservoirs of MRCV (Lenardón et al., 1997; Truol et al., 2001; Laguna et al 2002; Arneodo et al., 2002; Velazquez et al., 2006). Field studies have shown that its populations abruptly increase during summer on wheat and also on several wild grasses in cultivated maize areas affected by MRCV (Remes Lenicov, unpubl. data).

Sanitary Importance. Pyrophagus tigrinus was first captured in 1997 in Jesús María (Córdoba) in triticale crops infected by MRCV. Recently, Velazquez et al. (2006) demonstrated its capacity to transmit the MRCV to triticale under experimental conditions. They found similarities in the symptoms and the viral dsRNA electrophoretic pattern with the MRCV using D. kuscheli as vector. They also observed MRCV-like particles in phloem tissue cells and highlighted the possible role of P. tigrinus as vector and reservoir of virus in nature as well as its implication in the spread of this disease.

Natural Enemies. Nymphs and adults were found parasitized by one unidentified species of Elenchidae (Strepsiptera) .

Type Material. Holotype ♂ (macropter): ARGENTINA, Córdoba, Jesús María, on wheat, 10.xi.1988, Velázquez col. Paratypes: 3♂♂ (brachypters), 3♀♀ (macropters), 2♀♀ (brachypters), same data as holotype; 2♂♂ (macropters), 2♀♀ (brachypters), Tucumán, La Virginia, 11.xii.2008, Virla col.; 1♂ (macropter), 1♀ (brachypter), Buenos Aires, La Plata, on maize, xii.1989, Remes Lenicov col. ( MLP); 1♂ (macropter), 1♀ (brachypter), Buenos Aires, La Plata, on maize, xii.1987, Remes Lenicov col. ( MBR).

Other Material Exmined. ARGENTINA: Jujuy, 1♂, San Pedro, s/ Cynodon sp., 6.iv.1999, Virla col.; 1♀, Humahuaca, 8.iv.1999, Virla col. Salta: 1♂, Tolloche, 6.i.1999, Virla col.; 1♀, Pichanal, 24.iii.2000, Virla col.; 2♂♂, La Estrella, 5.iv.1999, Virla col.; 2♂♂, Tolombon, 21.iii.2000, Virla col.; 2♀♀, Ceibalito, on maize, 5.iv.1999, Virla col.; 2♂♂, Cabeza de Buey, on Sorghum halepense, tillered maize, 17.v.1994, Virla col.; 2♂♂, Rosario de Lerma, on oat, 17.v.1994, Virla col.; 1♂, 1♀, Cobos, tillered oat, 18.viii.2001, Virla col.; 2♀♀ (brachypters), Metán, on tillered wheat, 18.viii.2001, Virla, col. Tucumán: 4♂♂, 2♀♀, El Cadillal, on grass, xii.1942, Virla col.; 1♂, Burruyacu, 24.ii.2002, Virla col.; 2♀♀, Gdor. Garmendia, 24.ii.2002, Virla, col.; 1♀, Amaicha del Valle, on tillered barley, 19.viii.2001, Virla col.; 1♂, Chilcas, 25.iv.2000, Virla col.; 1♂, 1♀, Macomitas, 19.x.1999, Virla col.; 2♂♂, Leales, on oat and Melilotus sp., 16.ix.1990, Virla col.; 1♂, El Mollar, 3.v.1999, Virla col.; 1♂, Ampimpa, 2300 m, on wheat, 21.iii.2000, Virla col.; 1♂, 1♀, El Cadillal, on maize, 7.i.1993, Virla col.; 1♂, Rumi Punco, 20.ii.1999, Virla col. Catamarca: 1♀, El Alamito, 28.ii.1999, Virla col., 1♂, Cnia. del Valle, 25.ii.1999, Virla col.; 1♂, S.F. del Valle, on grass, 27.ii.1999, Virla col.; 2♂♂, Santa María, on barley, 13.vi.2001, Virla col.; 2♀♀, Huillapima, 438 m, 4.xii.2001, Virla col. Santiago del Estero: 2♂♂, Campo Experimental La María, Ruta 9 km.1109, Virla col.; 1♂, Santiago del Estero, 27.ii.1998, Virla col.; 1♂, 1♀, Las Romanos, on maize, 27.ii.1998, Virla col.; 2♀♀ (brachypters), Loreto, on oat in flowering stage, 11.ix.2001, Virla col.; 1♀, Isca Yacu (Pozo Hondo and Las Cejas), on oat in flowering stage, 11.ix.2001, Virla col. Chaco: 2♀♀, Charata, on oat in vegetative stages, 27.viii.2000, Virla col.; 1♂, Resistencia, 4.i.1999, light trap, Virla col. La Rioja: 1♂, San Blas, on maize V5–8 stage, 30.xi.2001, Virla col.; 1♂, Villa Mazán, 4.xii.2000, Virla col.; 1♀, Nonogasta, 3.xii.2001, Virla col. San Juan: 2♂♂, Villa Media Agua, 560 m, on grass, 1.xii.2001, Virla col.; 1♂, Jachal, on oat, 20.iii.2002, Virla col. San Luis: 1♂, Merlo, on grass, xi.1999, Remes lenicov col.; 1♂, Villa Mercedes, xii.1999, Virla col. Mendoza: 2♂♂, 1♀, Uspallata, on potatoe, iv.1945, Lanatti col. Misiones: 1♂, Aristóbulo del Valle, on grass, 1.iii.2001, Virla col. Corrientes: 1♂, 1♀, Santo Tomé, ii.1991; 1♀, San Roque, 2.iii.2001, Virla col. Entre Ríos: 3♂♂, 2♀♀, Colón, ii.1991, Remes Lenicov col. Santa Fe: 1♂, Suardi, on maize, 26.ii.2001, Laguna col. Córdoba: 1♂, 1♀, Piquillin, on sorghum, 25.xi.2003; 2♂♂, 3♀♀, Manfredi, on S orghum, xii.1992, Remes Lenicov col.; 2♂♂, 2♀♀, Río Cuarto, on maize, xii.1992, Dagoberto col.; 1♀, Jesús María, on wheat, x.1988, Truol col.; 2♂♂, Las Peñas, on maize, 2.xii.2002, Truol col. Buenos Aires: 3♂♂, 2♀♀, Peña, on wheat, iv.1944; 1♂, 1♀, José C. Paz, xii.1947, Martínez-Bezzi, col.; 2♂♂, 2♀♀, Bragado, on S orghum, i.1980, Remes Lenicov col.; 3♂♂, 2♀♀, La Plata, on maize, xii.1987, Remes Lenicov col.; 2♂♂, 1♀, Castelar, on wheat, maize, grass, xii.1980, Dalbo col.; 1♂, 2♀♀, Gorina, on parsley, alfalfa and clover, xii.1981, Dagoberto col. BRAZIL: 1♂, Parana, on maize, xii.2006, Martins col.; 1♂, Goias, on maize, xii.2006, Martins de Oliveira col.

Figures

FIGURES 1 – 14. Pyrophagus tigrinus sp. n. 1, head, frontal view; 2, head and thorax, dorsal view; 3, habitus, lateral view; 4, 2 nd sternal apodemes; 5, hind leg; 6, metatibial spur; 7, left paramere, posterior view; 8, aedeagus, lateral view (left side); 9 tip of aedeagus; 10, genitalia without pygofer, lateral view (left side); 11, genitalia, ventrocaudal view; 12, pygofer and anal segment, caudal view; 13, valvifer VIII, ventral view (left side); 14, tip of abdomen, ventral view; 15, gonapophysis IX, left lateral view. (scale bars in Figs 1, 2 and 9, = 0.1 mm; scale bars in other figures = 0.5 mm).