Trabajo Científico Article ISSN 0373-5680 (impresa), ISSN 1851-7471 (en línea) Revista de la Sociedad Entomológica Argentina 72 (3-4): 169-178, 2013 A new Neotropical species of Megamelus and the reassignment of Stenocranus maculipes (Hemiptera: Delphacidae) MARIANI, Roxana1, Alejandro J. SOSA2 & Ana M. M. de REMES LENICOV1 1División Entomología, Museo de La Plata, Paseo del Bosque s/n, B1900DNG La Plata, Argen- tina. E-mail: [email protected] 2Fundación para el Estudio de Especies Invasivas (FuEDEI), General Simón Bolívar 1559 (1686), Hurlingham, Buenos Aires, Argentina. E-mail: [email protected] Una nueva especie neotropical del género Megamelus y nueva combinación para Stenocranus maculipes (Hemiptera: Delphacidae) RESUMEN. Se estudian dos especies de Delphacidae que habitan en humeda- les de la Argentina, Megamelus nigrifasciatus Mariani & Remes Lenicov sp. nov. y Megamelus maculipes (Berg) comb. nov. La primera fue colectada sobre Eryn- gium sp. (Apiales: Apiaceae) y se describe a partir de formas braquípteras de ambos sexos. Además, se propone a Stenocranus maculipes (Berg, 1879), co- lectada en Echinodorus grandiflorum (Alismataceae), como Megamelus maculi- pes comb. nov. Se redescribe el holotipo hembra macróptero y se describen por primera vez los braquípteros de ambos sexos. Se aportan datos distribucionales y biológicos de las especies tratadas y se menciona por primera vez al género Eryngium como hospedante del género Megamelus. Asimismo, se provee una clave para la identificación de las siete especies sudamericanas de Megamelus. PALABRAS CLAVES. Megamelus nigrifasciatus. Megamelus maculipes. Apia- ceae. Alismataceae. América del Sur. ABSTRACT. We report on two species of Delphacidae from Argentine wetlands, Megamelus nigrifasciatus Mariani & Remes Lenicov sp. nov. and Megamelus macu- lipes (Berg) comb. nov. The first species was collected from Eryngium sp. (Apiales: Apiaceae) and was described from the brachypters of both sexes. The second one, Stenocranus maculipes (Berg, 1879) collected from Echinodorus grandiflorum (Alis- mataceae), is proposed as Megamelus maculipes comb.nov. The female macropter holotype is redescribed and the male and female brachypters are described for the first time. Geographic distribution and biological data of both species are reported. The genus Eryngium is cited for the first time as host plant for the genus Megame- lus. Additionally, a key is provided to distinguish among the seven South American species of Megamelus. KEY WORDS. Megamelus nigrifasciatus. Megamelus maculipes. Apiaceae. Alis- mataceae. South America. INTRODUCTION and the lobed appearance of the male pygofer The genus Megamelus Fieber (Hemiptera: (Beamer, 1955). It is represented in the Ameri- Delphacidae) is characterized by a narrow cas by 25 species, five of which occur on three head, long vertex extending beyond the eyes, aquatic plant families from South American wet- Recibido: 31-VII-2013; aceptado: 21-X-2013 169 Revista de la Sociedad Entomológica Argentina 72 (3-4): 169-178, 2013 lands: Megamelus bellicus Remes Lenicov & female brachypter. To preserve the unique type Sosa on Pontederia cordata L., P. rotundifolia L., specimen of M. maculipes comb. nov. (no. 1706 Eichhornia crassipes (Martius) Solms-Laubach, MLP collection), the description was based only E. azurea Kunth (Pontederiaceae) and Echino- on external anatomical features, the sixth ster- dorus grandiflorum (Chamisso & Schlechten- nite, the outline of valvifer VIII and the length dal) (Alismathaceae); M. electrae Muir on E. of the ovipositor. In addition, female macrop- crassipes and E. azurea; M. iphigeniae Muir on ters and brachypters and male brachypters P. parviflora Alexander, E. crassipes and E. azu- captured in the vicinity of the type locality, and rea; M. scutellaris Berg 1883 on E. crassipes; structurally identical — in coloration pattern and and M. timehri Muir on Limnobium spongia anatomical features — to the type specimen, (Bosc) Steudel subsp. laevigatum (Humboldt & were used for dissections, illustrations and com- Bondpland ex Willdenow) (Hydrocharitaceae) plementary descriptions. (Sosa et al., 2004; Sosa et al., 2007a). Male and female genitalia were prepared Due to the interest sparked by M. scutellaris, for microscopic examination. Illustrations were a South American species released in the USA drawn using a stereoscopic microscope with as a biocontrol agent against E. crassipes (Sosa camera lucida. Measurements were taken from et al., 2007b; Tipping et al., 2011, Fitzgerald & ten specimens of each sex, with winged forms Tipping, 2013), much more attention has been included when possible, and are given in mil- paid to this genus, its biology and host plants limeters, with the average followed by the range in the Neotropics. Several specimens of Meg- in parentheses. Abbreviations are as follows: amelus spp. were collected from Eryngium sp. L., total length; B.L., body length; t.l., tegmina (Apiaceae) and E. grandiflorum (Alismataceae) length; v.l., vertex length; v.w., vertex width at in recent explorations of Argentinian wetlands. base; f.l., frons length; M.f.w., maximum frons These studies revealed the new species Meg- width; m.f.w., minimum frons width; a.l.I, first an- amelus nigrifasciatus, described herein, and tennal segment length; a.l.II, second antennal suggested the new combination Megamelus segment length; p.l., pronotum length; m.l., me- maculipes, based on examination of the fe- sonotum length; mti.l., metatibia length; mta.l., male macropter holotype and the description metatarsi length; mta.I, first hind tarsomere of the previously unknown male and female length; s.l., metatibial spur length; t.n., number brachypters. A key for the South American spe- of teeth on metatibial spur. cies, modified from Sosa et al. (2007a), is also Specimens were deposited in the MLP col- presented here to facilitate species identifica- lection. Label information for primary types is tion. Data on distribution and biology are includ- quoted, with each line break indicated by “/”and ed, highlighting the discovery of Eryngium sp. each label separated by “//”. as a new host plant for the genus Megamelus. Laboratory rearing MATERIAL AND METHODS Adults were collected in the provinces of En- tre Ríos and Buenos Aires (Argentina), during Morphological studies surveys that took place in 1999, 2001, 2002, The adults examined came from field surveys 2004 and 2007. Specimens were transported in the Paraná–Uruguay Basin wetlands (approx- alive to the FuEDEI, where several generations imate range 25º–35º S) (according to Bonetto & of M. nigrifasciatus and M. maculipes were Hurtado, 1998) in Argentina, made from 1999 reared on Eryngium sp. and E. grandiflorum, re- to 2007. A few specimens belong to the collec- spectively, using potted plants placed in three tions of Museo de La Plata (MLP) (FCNyM-UN- 300-liter canvas pools, under outdoor condi- LP), Facultad de Ciencias Exactas y Naturales, tions. Some host plants were reared separately Universidad de Buenos Aires (FCEyN), the field and analyzed under the microscope to search specimens were collected directly from plants for oviposition marks, some of which were later using insect aspirators. isolated to obtain egg parasitoids. Preliminary The male brachypter of M. nigrifasciatus sp. host range studies were performed by adding nov. was described in detail, while only major other species of aquatic plants: the Pontede- morphological traits were considered for the riaceae P. cordata, P. rotundifolia, P. subovata 170 MARIANI, R. et al. New Megamelus species and Stenocranus maculipes reassignment (Seubert) Lowden, E. crassipes, E. azurea, and weaker basally. Rostrum reaching metacoxae, Heteranthera limosa (Swartz) Willdenow, and longer than frons, subapical segment longer the Hydrocharitaceae L. laevigatum. Further ob- than apical one (1.16:1). Antennae with first servations of adults, nymphs and ovisoposition segment 2 times longer than wide, second seg- scars were made on all plants. ment 1.25 times the first, length twice and half its width (Fig. 2). Pronotum with conspicuous RESULTS carinae, laterals divergent, straight to slightly convex, reaching hind margin. Mesonotal disc Megamelus nigrifasciatus Mariani & Remes almost as long as pronotum, carinae conspicu- Lenicov sp. nov. (Figs. 1–14) ous, lateral ones reaching hind margin (Fig. 1). Metatibial spur leaf-like, short and narrow, with Male brachypter (Figs. 1–11). Color: brown. a median longitudinal rib, bearing 10-13 black- Vertex lighter, darker spots on base, middle and tipped regular teeth on trailing margin, almost apex of lateral carinae, and apex of submedian one quarter shorter than first segment of meta- carinae on fastigium. Frons lighter, with small ir- tarsi; first hind tarsomere longer than the sec- regular darker spots on base, followed by two ond plus third (2:1) (Fig. 4 a–b). narrow irregular stripes extending towards the Terminalia (Figs. 5–11). Pygofer dorsally with gena, one whitish, one blackish, and a third, shallow concave anal emargination, anal angles regular wider whitish stripe at apex. Clypeus rounded, slightly projected caudad (Fig. 6); dark brown at base and laterally. First anten- ventral margin with large round kidney-like outer nal segment darker than second, with a median lobes, partially enfolding lateral area of pygofer blackish stripe frontally. Pronotum lighter be- (Fig. 5), rhomboid shaped inner lobes —acute in tween lateral carinae near the vertex; mesono- outline—, emarginated and depressed