New geographical records and key to the species of Eumerus Meigen, 1823 (Diptera, Syrphidae) introduced into the Americas and Hawaii

Abstract Eumerus Meigen, 1823 is a very speciose genus of flower flies from the Eastern Hemisphere. Several reports of introduced species of this genus in the Americas have been recorded since early in the twentieth century, with a present list of six species recorded to date from the Americas and the US territory of Hawaii. In this paper we give new geographical records for the African-native species Eumerus obliquus (Fabricius, 1805), which reflect the expansion of this fly through Brazil and Paraguay along the last twenty years. At the same time, we report a second species from Paraguay, Eumerus aurifrons (Wiedemann, 1824), being this the first Western Hemisphere record for this Asian-native species. We finally provide an identification key to all of the species of Eumerus presently known from the Americas and Hawaii.

Palpada panorama sp. n. (Diptera: Syrphidae), a big-eyed hoverfly from Peru and Suriname.

The hoverfly species Palpada panorama sp. n. (Diptera: Syrphidae) is described based on specimens from Peru and Suriname. It belongs to the scutellaris species group and it is most similar to P. erratica (Curran, 1930), from which it differs most notably by the strongly enlarged ommatidia in the upper half of the eye. Additional differences between these two species and an adjustment for the latest identification key for the species of the scutellaris group are given.

Natural history and morphology of the hoverfly Pseudomicrodon biluminiferus and its parasitic relationship with ants nesting in bromeliads.

The syrphid subfamily Microdontinae is characterized by myrmecophily of their immature stages, i.e., they develop in ant nests. Data on natural history of microdontines are scarce, especially in the Neotropics. Based on fieldwork in southern Brazil, this study provided new data on development and ecology of the hoverfly Pseudomicrodon biluminiferus (Hull) (Diptera: Syrphidae) as well as the first morphological descriptions of male genitalia, larvae, and pupa. Immature specimens were specifically found in colonies of the ant species Crematogaster limata Smith (Hymenoptera: Formicidae) found in rosettes of the bromeliad species Aechmea lindenii (E. Morren) Baker (Poales: Bromeliaceae) and A. nudicaulis (L.) Grisebach. Third instar larvae were observed preying on ant larvae, revealing the parasitic nature of P. biluminiferus. In this and several other aspects, the natural history of P. biluminiferus is similar to that of Holarctic microdontine species. Exceptions include: (i) indications that adults of P. biluminiferus outlast the winter months (in contrast to 3(rd)instar larvae in Holarctic species) and (ii) P. biluminiferus' relationship with bromeliads. The importance of bromeliads for this host-parasite system is evaluated in this paper. The single occurrence of another, unidentified microdontine species' pupae in a nest of the ant species Camponotus melanoticus Emery (Hymenoptera: Formicidae) is reported.

Espécies de Syrphidae (Diptera) visitantes das flores de Eryngium horridum (Apiaceae) no Vale do Rio Pardo, RS, Brasil

Between December 2001 and December 2003, collections of flower visitors of Eryngium horridum (Apiaceae) were carried out in areas of Rio Pardo Valley, RS, Brazil. This plant is perennial, commonly found in dry fields, presenting a wide distribution. Its flowering period ranges from November to January in Rio Grande do Sul. A total of 1,066 insects were captured, 569 of them belonging to Syrphidae. Sixty species of Syrphidae were identified, distributed in 16 genera. The genus Palpada Macquart, 1834 was considered dominant, and Ornidia Lepeletier & Serville, 1828 and Toxomerus Macquart, 1855 considered abundant. Palpada furcata (Wiedemann, 1819) was the most abundant species. The syrphids showed a preference for temperatures between 28 and 32ºC, and were more frequently collected between 10 and 14 hours, with peaks between 10 and 11 hours. The females were more frequent. The predominance of robust and agile syrphids over those with lower proportions, such as Toxomerus and Allograpta Osten Sacken, 1875, may have been a result of interespecific competition. Eristalinus taeniops (Wiedemann, 1818) is newly recorded from Rio Grande do Sul state. The high diversity and abundance of the species collected from flowers of E. horridum are indicators of the importance of this plant on the diet of the syrphids, since it possesses an elevated number of inflorescences that bloom in months of low resource availability in the study area.

No período entre dezembro de 2001 a dezembro de 2003, realizaram-se coletas com rede entomológica de insetos visitantes das flores de Eryngium horridum (Apiaceae) na Região do Vale do Rio Pardo, RS, Brasil. Esta planta é perene, freqüente em campos secos e apresenta expressiva dispersão. Possui, no Rio Grande do Sul, época de floração entre novembro e janeiro. Foram capturados 1.066 insetos visitantes, destes, 569 Syrphidae. Identificaram-se 60 espécies de Syrphidae, distribuídas em 16 gêneros. O gênero Palpada Macquart, 1834 foi dominante, e Ornidia Lepeletier & Serville, 1828 e Toxomerus Macquart, 1855 abundantes. Das espécies mais freqüentes, Palpada furcata (Wiedemann, 1819) ocupou posição mais elevada. Os sirfídeos apresentaram preferência pelas temperaturas entre 28 e 32ºC, e foram mais freqüentemente coletados entre as 10 e 14 horas, com picos entre as 10 e 11 horas. As fêmeas foram as mais freqüentes. O predomínio de sirfídeos robustos e mais ágeis sobre sirfídeos de menor porte como Toxomerus e Allograpta Osten Sacken, 1875, pode ter sido resultante de competição interespecífica. Eristalinus taeniops (Wiedemann, 1818) é pela primeira vez citada para o Estado do Rio Grande do Sul. A alta diversidade e abundância dos espécimes coletados nas flores de E. horridum são indicadores da importância desta na dieta dos sirfídeos, visto que possui grande número de inflorescências e floração ocorrendo nos meses de baixa oferta de recursos alimentares na área de estudo.