Eristalis (Eoseristalis) gatesi Thompson
Eristalis (Eoseristalis) gatesi Thompson, 1997.
Thompson, F. C. (1997) Revision of the Eristalis flower flies (Diptera: Syrphidae) of the Americas south of the United States. Proceedings of the Entomological Society of Washington 99: 209-237. [1991.05.15]
Eristalis gatesi belongs to a group (Eristalis) characterized by wing venation (closed and petiolate cell R1 and sinuate vein R4+5), a basolateral setose patch on the hind femora, eye pilose, katepimeron bare, and wing bare apically. Eristalis gatesi differs from the other species in this group by its unique color pattern of black and yellow on the abdomen.
The subgenus Eoeristalis differs from Eristalis sensu stricto by having katepimeron bare (pilose in Eristalis s.s.).
Eristalis gatesi as an adult is a typical flower fly, visiting flowers for pollen and nectar. Males also hover in the air near flowering plants. Nothing specific is known of the immature stages, but they are probably similar to those of other eristaline flower flies. The maggots of eristaline flies live in aquatic habitats, breathing air through long tails which reach to the water surface (hence, are called rat-tailed maggots). They feed by filtering nutrients from the water.
Adapted from original description (Thompson 1997).
Head: face tawny brown except broadly black along oral margin and with black medial vitta extending over tubercle, brown pollinose, with pollinosity sparse on black areas, yellow pilose; gena black, sparsely gray pollinose, yellow pilose posteriorly; frontal lunule orange; frontal triangle black, gray pollinose, yellow pilose with a few black hairs intermixed; eye pile brown; eye contiguity long, as long as vertical triangle, about 3/4 as long as frontal triangle; antenna orange except narrowly brownish black on dorsal edge of basoflagellomere, black pilose; arista orange, sparsely pilose on basal 1/2, with 5-6 long dorsal hairs and more short vertical ones, with dorsal hairs about as long as 2nd antennal segment width; occiput densely white pollinose, yellowish white pilose ventrally becoming yellow orange dorsally, with black cilia on dorsal 1/4.
Thorax: black; scutum gray pollinose, without pattern, yellow pilose except with black pile intermixed posteriorly; pleuron gray pollinose, black pilose except with yellow pile intermixed on episternum; postalar callus black pilose; scutellum brown pollinose, black pilose; squama black; halter gray with black knob; spiracular fringes black. Wing: fumose basally, hyaline apically, bare; tegula black pilose. Legs: black, black pilose except yellow pilose on protibia and pro- and mesotarsi; metafemur narrow, very slightly arcuate, without short black apicoventral spinose hairs.
Abdomen: 1st tergum black, black pollinose, black pilose; 2nd tergum yellow except black T-shaped basomedial macula and black basolaterally, black pilose except for a few yellow hairs basomedially; 3rd tergum yellow except for black T-shaped apicomedial macula, black pilose; 4th tergum black, black pollinose except shiny medial macula, black pilose; genitalia black, sparsely black pollinose, black pilose; 1st sternum black, gray pollinose, black pilose except for a few yellow apicomedial hairs; 2rd and 3rd terga yellow except narrowly black medially, shiny, yellow pilose; 4th sternum black, shiny, black pilose except yellow pilose apicomedially.
Similar except abdomen more extensively black; frons brown pollinose, brownish orange pilose, about 0.40 times as wide as head at antenna, tapering to about 0.20 times as wide dorsally; 2nd tergum black except narrowly yellow apically, black pollinose except yellow on apical margin, entirely black pilose; 3rd tergum yellow except black laterally and medially, black pilose; 4th tergum as in male; 5th tergum black, black pollinose basally, shiny apically, black pilose; 2nd thru 5th sterna black, shiny, black pilose.
No other flower fly has the unique black and yellow color pattern on the abdomen.
Ecology and Distribution
Eristalis gatesi is only known from the higher elevations in Costa Rica (Brava, Cerro Chirripo & Muerte, Volcan Poas).
Eristalis gatesi is found commonly along edges in the forest in the higher montane areas (2,500 and above).
Eristalis gatesi has been collected on the flower of Seneico oerestedinaus Benth and off the leaves of Vaccinium.
Evolution and Systematics
Nomenclature and Synonymy
This species was described by Thompson in 1997 in the Proceedings of the Entomological Society of Washington, volume 99, issue 2, on page 227. The holotype was collected in Costa Rica, Heredia, Braulio Carrillo National Park, at Estacion Barva, 2,500 m and is now in Instituto Nacional de Biodiversidad, Santo Domingo. The species was named in honor of William Gates III, the co-founder of Microsoft. The species has only been described once; there are no synonyms.
Beyond being a member of the subgenus Eoseristalis of the genus Eristalis and the placement of that genus in the hierarchy of the flower flies, not further is known of the phylogenetic placement of this species.
This species is restricted to the higher elevations in Costa Rica and is found no where else. Hence, vulnerable to habitat destruction via human incursion and global warming.
There is no specific legal regulations or statutes relating to this taxon beyond the Costa Rican government's general ones related to biodiversity.
So long as the national parks where this species occurs are properly managed, this species should survive.
This species is of no risk to humans or their environoment.
The only scientific publication related to this species is given above. However, images of this species have widely published in the popular press, from the New York Times to Der Spiegel.