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Revista de la Sociedad Entomológica Argentina

Print version ISSN 0373-5680

Rev. Soc. Entomol. Argent. vol.70 no.3-4 Mendoza July/Dec. 2011

 

NOTA CIENTÍFICA

First record of the genus Homalodisca (Hemiptera: Cicadellidae) from Argentina and redescription of the female of H. ignorata

Primer registro del género Homalodisca (Hemiptera: Cicadellidae) en Argentina y redescripción de la hembra de H. ignorata

 

Dellapé, Gimena and Susana L. Paradell

Universidad Nacional de La Plata, División Entomología, Facultad de Ciencias Naturales y Museo, La Plata, Buenos Aires, Argentina; e-mail: gimenadellape@gmail.com; paradell@fcnym.unlp.edu.ar

Recibido: 11-V-2011
Aceptado: 27-VI-2011

 


ABSTRACT. The genus Homalodisca Stål and the species H. ignorata are recorded for the first time in Argentina, from specimens collected in Misiones province. This contribution adds diagnostic characters of the female of H. ignorata and compiles information about the geographical distribution and association with diseases of all known species of the genus.

KEY WORDS. Sharpshooters; Proconiini; Homalodisca; Xylella fastidiosa.

RESUMEN. El género Homalodisca Stål y la especie H. ignorata Melichar son citados por primera vez en Argentina, a partir de ejemplares colectados en la provincia de Misiones. En esta contribución, se adicionan caracteres diagnósticos de la hembra de H. ignorata y se reúne información acerca de la distribución geográfica y la asociación con enfermedades de todas las especies conocidas del género.

PALABRAS CLAVE. Cicadelinos; Proconiini; Homalodisca; Xylella fastidiosa.


 

The subfamily Cicadellinae comprises exclusively phytophagous insects, many of which are involved in the transmission and spread of pathogens in cultivated and wild plants (Nielson, 1968).
The tribe Proconiini Stål includes 58 genera and 422 species, all distributed in the continental Americas (Wilson et al., 2009). So far, about 30 species are represented mainly in the northwest, east and center of Argentina (Paradell et al., 2008).
Sharpshooters are well-known because of their particular feeding habits, sucking the xylem of a wide variety of plants. As a consequence, they have economic
significance because of their ability to transmit diseases, especially to fruit, vegetable and ornamental plants. The main transmitted organism is the pathogenic bacterium Xylella fastidiosa Wells et al., causal agent of "Phony Peach Disease", "Pierce's Disease" of grapes, "Coffee Leaf Scorch" and "Citrus Variegated Chlorosis" among others. The main vectors are species in the genera Homalodisca Stål, Oncometopia Stål, Cuerna Melichar and Acrogonia Stål (Redak et al., 2004).
Sampling in Misiones province resulted in the capture of numerous specimens belonging to the genus Homalodisca. The purpose of this contribution is to formally record this
genus for Argentina, add characters for the diagnosis of the female of H. ignorata Melichar and compile information on the geographic distribution and association with diseases of all species of the genus.
The specimens studied are deposited in the Entomology Collection of Museo de Ciencias Naturales de La Plata (MLPA). Other specimens were studied from Illinois Natural History Survey (INHS).

Homalodisca Stål, 1869

Stål, 1869: 63. Type species: Cicada triangularis Fabricius.

Diagnosis. According to Young (1968), this genus is characterized by the following diagnostic features: length 15 mm or less, head strongly produced, anterior margin rounded in dorsal aspect, usually with a slight angle at transition from crown to face, disc of crown flattened; proepimeron without ventral depressed region, metepimeron with shelflike projection upon which forewings rest when in rest position, forewing at rest exposing meron of hindleg, hindwing with vein R2+3 incomplete; abdomen not constricted basally; male genitalia without paraphyses, and plates separate throughout their length.
Homalodisca includes 18 species distributed from USA to Brazil found on several cultivated, ornamental and wild plants (Takiya, 2008).

Homalodisca ignorata Melichar, 1924 (Figs.1-10)


Fig. 1. Female Homalodisca ignorata Melichar. A, Lateral view, B, dorsal view.


Figs. 2-10. Homalodisca ignorata Melichar. 2, Sternite VII; 3, pygofer, lateral view; 4, pygofer and third valvulae of ovipositor, ventral view; 5, first valvifer; 6, apex of first valvulae of the ovipositor; 7, second valvifer; 8, second valvulae of ovipositor, lateral view; 9, apex of second valvulae; 10, teeth of median portion of second valvulae of ovipositor. Scale: Figs. 2-5 and 7-8 = 0,5mm; Figs. 6 and 9 = 0,1mm; Fig.10 = 0,05mm.

Homalodisca ignorata Melichar, 1924: 240.

Diagnosis. Crown and pronotum light brown with black areas; claval veins fused for considerable distance; posterior margin of female abdominal sternite VII with broad median lobe, abdominal sternite VIII of female with two pairs of conspicuous lateral plates sclerotized; shaft of aedeagus robust with gonopore conspicuously visible, aedeagus with pair of ventral processes, processes of pygofer not attaining pygofer apex (Young,1968; Azevedo & Carvalho, 2006).
In this contribution, we describe and add the following additional diagnostic characters of the female genitalia: abdominal sternite VII (Fig. 2) with microsetae distributed throughout disc; pygofer (Figs. 3, 4) rectangular in lateral view, microsetae distributed irregularly on disc, posterior margin truncate. First valvifer (Fig. 5) subquadrate, with microsetae along posterior margin, small dots irregulary distributed on its caudoventral surface; first valvulae of ovipositor (Fig. 6) with apical area denticulate on ventral margin, apex acute, slightly curved downward. Second valvifer (Fig. 7) rectangular, with slightly concave ventral margin and microsetae distributed in one small group on caudoventral area. Second valvulae of ovipositor (Figs. 8, 9, 10) with blade bearing approximately 32 teeth, each tooth subtriangular, declivous posteriorly, with uncountable denticles throughout entire dorsal margin; preapical ventral prominence present; apical portion with denticles on ventral margin, apex rounded.
The type-specimen is deposited in Moravian Museum (Brno, Czech Republic).

Remark. H. ignorata is most similar to H. ignota Melichar in having the pygofer of male with a ventral process well developed; morphology and microsetae of pygofer of female and teeth of second valvulae of ovipositor. H. ignorata can be distinguished from other Homalodisca species by the large black spot on the basal area of the clypeus and by its aedeagal morphology.

Material examined. ARGENTINA. Misiones: Eldorado, 31-X-2008, Logarzo-Palottini legs., 1 male, 4 females (MLPA). BRAZIL. Sao Paulo: Bebedouro, 14-V-1998, Roberto S. leg., 3 males, 1 female. Determined by R.C. Marucci and C. Dietrich (INHS).

Distribution. Brazil (Minas Gerais, Cafelandia, Comendador Gomes, Paraná, Fenix, Reserva Estadual de Vila Rica, Rio de Janeiro, Niteroi, Rio Grande do Sul, Cerro Largo, Montenegro, Porto Alegre, São Leopoldo, Taquari, Viamao, Santa Catarina, Chapeco, São Paulo, Araraquara, Bebedouro, Colina, Olimpia, Paulo de Faria); Paraguay (Central, Santa Clara, Jaguaron) (See distribution map in the Sharpshooters database http://ctap.inhs.uiuc.edu/takiya/ taxahelp.asp?hc=815&key=Proconia&lng=En).
H. ignorata is a vector of Citrus Variegated Chlorosis and Coffee Leaf Scorch in Brazil (Yamamoto et al., 2000; Marucci et al., 2002) and is the only species of the genus Homalodisca considered a vector of X. fastidiosa in South America (Table I).

Table I. Geographic distribution and disease association of all species of the genus Homalodisca Stål (Data compiled from Young, 1968; Takiya, 2008 and Redak et al., 2004). References. AD: Alfalfa Dwarf Disease; ALS: Almond Leaf Scorch; CLS: Coffee Leaf Scorch; CVC: Citrus Variegated Chlorosis; PD: Pierce's Disease of grapevine; PPD: Phony Peach Disease.

ACKNOWLEDGEMENTS

The authors wish to thank Dr Chris Dietrich for the loan of specimens, Dr Guillermo Logarzo for the material collected and Lic. Leopoldo Alvarez and Lic. María Schenone for the photography. This work was supported by Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC) and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET).

LITERATURE CITED

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