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Two new species of Rhaphiomidas (Diptera: Mydidae)
Abstract
Two new species of Mydidae, Rhaphiomidas pachyrhynchus sp. nov. and Rhaphiomidas moapa sp. nov. are described and illustrated here for the first time. Rhaphiomidas pachyrhynchus represents the southeastern most record of the genus. Notes on the adult ecology of R. moapa are given.
Despite harsh climatic conditions and low and erratic rainfall patterns, the United Arab Emirates’ (UAE) terrestrial arthropod fauna is diverse and extremely well adapted to the local environment, with some species occurring in high abundance. Until recently, the UAE’s terrestrial arthropods were poorly studied. The past two decades have seen the knowledge of arthropod diversity increase dramatically, with more than 4000 species now known to occur in the Emirates, including hundreds of species that were previously unknown for the UAE and had never been recorded globally. With so many species recently added to the inventory of the nation, their ecology (i.e., life cycles, interactions, habitat needs) are yet to be studied. This presents a challenge for conservation planning, but also offers many opportunities for further study of these organisms. Where the life-histories of species are known, they demonstrate that arthropods of the UAE are an integral part of local food webs and contribute essential ecosystem services. As is the case globally, the UAE’s arthropods are under threat from habitat loss and destruction. The lack of long-term monitoring programs means that it is currently not possible to assess whether the trend of arthropod biodiversity loss seen worldwide is echoed in the UAE.
The Early Cretaceous mydid genus and species Cretomydas santanensis is revised on the basis of a new specimen, allowing to precise its relationships within the ‘advanced Mydidae’, probably close to the subfamily Diochlistinae. This extant group has a ‘Gondwanan’ distribution, known from Southern South America and Australia, in accordance with its possible great antiquity in the Early Cretaceous. The presence of an ‘advanced Mydidae’ during the Cretaceous also suggests a greater antiquity for this family.
Aim
Phenology, the temporal response of a population to its climate, is a crucial behavioral trait shared across life on earth. How species adapt their phenologies to climate change is poorly understood but critical in understanding how species will respond to future change. We use a group of flies ( Rhaphiomidas ) endemic to the North American deserts to understand how species adapt to changing climatic conditions. Here we explore a novel approach for taxa with constrained phenologies aimed to accurately model their environmental niche and relate this to phenological and morphological adaptations in a phylogenetic context.
Taxon
Insecta, Diptera, Mydidae, Rhaphiomidas
Location
North America, Mojave, Sonoran and Chihuahuan Deserts.
Methods
We gathered geographical and phenological occurrence data for the entire genus Rhaphiomidas , and, estimated a time calibrated phylogeny. We compared Daymet derived temperature values for a species adult occurrence period (phenology) with those derived from WorldClim data that is partitioned by month or quarter to examine what effect using more precise data has on capturing a species' environmental niche. We then examined to what extent phylogenetic signal in phenological traits, climate tolerance and morphology can inform us about how species adapt to different environmental regimes.
Results
We found that the Bioclim temperature data, which are averages across monthly intervals, poorly represent the climate windows to which adult flies are actually adapted. Using temporally-relevant climate data, we show that many species use a combination of morphological and phenological changes to adapt to different climate regimes. There are also instances where species changed only phenology to track a climate type or only morphology to adapt to different environments.
Main Conclusions
Without using a fine-scale phenological data approach, identifying environmental adaptations could be misleading because the data do not represent the conditions the animals are actually experiencing. We find that fine-scale phenological niche models are needed when assessing taxa that have a discrete phenological window that is key to their survival, accurately linking environment to morphology and phenology. Using this approach, we show that Rhaphiomidas use a combination of niche tracking and adaptation to persist in new niches. Modeling the effect of phenology on such species' niches will be critical for better predictions of how these species might respond to future climate change.
This paper describes one new species, Rhaphiomidas ballmeri sp. nov. from Sonora state, Mexico. A new key is provided for males of this genus to aid in their identification.
The Delhi Sands Flower-loving Fly (Rhaphiomidas terminatus abdominalis Cazier), the only Dipteran listed as endangered in the United States, is a large, nectar-feeding pollinator fly, found only in remnants of a sand dune ecosystem in southern California. A five-year observational study was conducted in a 3.7ha preserve. Legal and biological constraints limit accuracy of population data because marking individuals was not possible. The population on the preserve appeared to be stable over the period of observation. Little variation in number of flies observed from year to year was found. Spatial distribution of fly observations differed for each fly generation, but reasons for this are not clear. Distribution of male and female flies differed from each other most of the time. Understanding aspects of the fly's ecology and behavior and the ecosystem dynamics is necessary to effectively plan for conservation and recovery of the species. Preserves must provide all of the elements needed for continued survival of the species through maintenance of its dynamic habitat.
Rhaphiomidas terminatus terminatus has been assumed extinct for over 30 years. In July of 2001 a small population was rediscovered. We provide a brief review of the known biology of Rhaphiomidas species and specifically address conservation concerns for R. terminatus terminatus.
The Delhi Sands flower-loving fly, Rhaphiomidas terminatus abdominalis Cazier, is the only dipteran listed as an endangered species by the U.S. Fish and Wildlife Service. Fewer than 500 individuals are believed to exist. Needs of this species are not well known, and understanding the behavior of this species may be a key element in designing a successful conservation and recovery plan. Behavior of adult flies was observed throughout 2 annual periods of activity (August-September) at a 3.7-ha preserve in southern California. Microhabitats present on the preserve included a range from dense shrubs (vegetation cover >75%) to open sand (vegetation cover <1%). Males and females differed greatly from each other in activity rate, specific behaviors, and use of habitat features. Males were very active, exhibited searching and pursuit flight, and were most often found in open areas. Females were more passive, spending most of the time perched on shrubs in areas with cover of >25%. While perched, females extended and vibrated their abdomens, which is postulated to be pheromone broadcast or semaphoring behavior. Flies appeared to be highly selective of microhabitats used for various behaviors, using only a small portion of the preserve, and males and females used different microhabitats. Preservation of a range of microhabitats is probably necessary to conserve the species, and habitat creation should include a range of microhabitats and plant species.
Twenty members of the fly families Apioceridae and Mydidae are compared in terms of 77 adult characters. Cladistic analysis of 91 synapomorphies provides a well corroborated reconstruction of lineage relationships, and reveals that the Apioceridae is paraphyletic with respect to the Mydidae. In order to render the Apioceridae monophyletic, the genus Rhaphiomidas and the subfamily Megascelinae of the Apioceridae are transferred to the Mydidae. The subfamily Rhaphiomidinae is reinstated to accommodate Rhaphiomidas, comprising the most plesiomorphic mydids. The relationships of the remaining subfamilies of Mydidae are discussed in the context of these findings. The genus Apiocera is divided into four subgenera, the type subgenus Apiocera Westwood in Australia, Pyrocera subgen. nov. in North America, and the subgenera Ripidosyrma Hermann and Anypenus Philippi are applied to the South African and South American species, respectively. A key to the four subgenera of Apiocera is provided. The biogeographic relationships of the subgenera and genera of the Apioceridae and the Megascelinae are discussed. Although considered an example of a transantarctic or Gondwanan group, we argue that the distribution of the Apioceridae predates the Mesozoic supercontinent Gondwanaland and extends onto sections of Pangaea, and should be termed ‘Pangaean'. The cladistic relationships between the genera of Apioceridae and Megascelinae are consistent with the geological vicariance of the fragments of Pangaea on which they now occur.
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