Morphological, Genetic and Biological Evidences to Understand Meromacrus Rondani Diversity: New Species and Early Stages (Diptera: Syrphidae)

Abstract

Meromacrus is a genus of conspicuous syrphids with saprophagous larvae, ranging from the southern United States to Argentina and Chile. However, this genus is in need of a taxonomic revision. Adults reared from larvae collected in Mexico and Peru, and other material available at different institutional collections were examined. Meromacrus cactorum sp. nov., from Peru, Meromacrus yucatense sp. nov., from Mexico, their puparia and breeding sites were described. A key to Meromacrus puparia is provided. The holotypes of Meromacrus canusium, Meromacrus gloriosus, Meromacrus laconicus and Meromacrus melmoth were also examined. The name Meromacrus draco is proposed as a junior synonym of M. gloriosus. Larvae of M. cactorum sp. nov. were found in decaying columnar cacti in Peru, while those of M. yucatense sp. nov. in a rot-hole of a Ceiba pentandra stump. Obtained results on both taxonomy and biology of these species serve as a first step towards a revision of the entire genus.

First records of Meromacrus cactorum (Diptera: Syrphidae) from Chile, with new biological data

“…The presence of Meromacrus in Chile has just been confirmed with specimens of Meromacrus laconicus (Walker) from fruit croplands of the transversal valleys (Barahona-Segovia et al, 2021) The new records of M. cactorum from Chile extend its known range for more than 1,500 km (in straight line) further southeast of the type locality in Peru (Ricarte et al, 2020;Fig. 2), indicating that it might be present all along the Peruvian coast.…”

“…The genus Meromacrus Rondani (Syrphidae: Eristalinae) has 44 species from the Southern United States to Northern Argentina and Chile (Ricarte et al, 2020;Barahona-Segovia et al, 2021). Adults visit flowers, for example, of Sapium glandulosum (L.) Morong (Euphorbiaceae) (Blatch et al, 2003) and mango, Mangifera indica L. (Anacardiaceae) (Jirón & Hedstrom, 1985;Blatch et al, 2003), pollinating flowers of this latter species (Jirón & Hedström, 1985;Castillo-Carrillo, 2013) as well as those of Miconia tonduzii Cogn.…”

“…Larvae of Meromacrus are saprophagous in various breeding sites of plants, from decaying cacti to tree rotholes, where they may coexist with other congeneric larvae or even with those of other eristalines (Blatch et al, 2003;Pérez-Bañón et al, 2003;Ricarte et al, 2020). The only evidence of Meromacrus breeding in decaying cacti is that of Meromacrus cactorum Ricarte et al in Espostoa melanostele (Cactaceae), from an arid cactusdominated habitat of Peru (Ricarte et al, 2020).…”

Combined stereomicroscope and SEM disentangle the fine morphology of the undescribed larva and puparium of the hoverfly Milesia crabroniformis (Fabricius, 1775) (Diptera: Syrphidae)

“…The head skeleton of M. crabroniformis shows distinctive features of a saproxylic larvae such as mandibular hook reduction, mandibles elongated and thin, pharyngeal ridges, and lateral lips covered by setae (Hartley, 1963;Gilbert, 1999, 2008). Such features evidence that M. crabroniformis filter the fluid media contained in chestnut rot holes to feed, in the same way as in other saproxylic larva, such as those of Meromacrus yucatense Ricarte et al, 2020 from rot holes of ceiba stump (Ricarte et al, 2020). In general, the sizes of the head skeleton vary according to syrphid species, with the feeding mode being the reason for the different sizes (Hartley, 1963).…”