Ephemeroptera: Baetidae of Gunnison County, ColoradoIntroduction to the Mayfly genus Acentrella
Minature Blue Winged Olive, Tiny BWO, Small Minnow Mayflies, Minute Graywinged BrownBengtsson, 1912
Updated 3.14.2024
TSN 100801
Species List
Good Links
On this website:
Baetidae Introduction
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Photos, Map, Museums, DNA - Barcode of Life Data System
Photos from Troutnut
Notes
Regarding the nymphs, both species lack a "thumb" on their labial palp which separates them from Baetis. They both have long setae on the backs of their legs as you can see in the photo below. A. insignificans has hind wing pads while A. turbida does not.
References
Bengtsson,S 1912 Neue Ephemeriden aus Schweden. Entomologisk Tidskrift 33:107-117.
Burian,SK and Myers,LW 2011 A new species of Acentrella Bengtsson (Ephemeroptera: Baetidae) from New York and New England (USA), redescription of the nymph of A. parvula (McDunnough), and key to known adult males of Nearctic Acentrella. Aquatic insects, 33(4)305-334.
Abstract: " A new species Acentrella rallatoma (type locality: Connetquot River, Oakdale, NY, USA) is described from nymphs and reared adults. Additional specimens were studied from southeastern New York, southeastern New Hampshire, coastal Connecticut, and Martha's Vineyard, MA, USA. Nymphs can be separated from those of other Nearctic species by: scraper-like outer incisors of mandibles, cerci alternately banded from bases to tips, and row of robust bristle-like setae (with modified tips) on dorsal edge of femora. Male imagos can be separated from those that lack hind wings by: distinctive colour pattern of abdominal terga, and genitalia with pigmented sclerotised penes cover. Comparative analysis of A. rallatoma with other Nearctic species revealed a lack of comparative data on nymphs of its presumptive sister species A. parvula. To facilitate future studies of this group, the nymph of A. parvula is redescribed and regional differences are discussed. Abdominal colour patterns of A. parvula that vary over its range from Florida, USA to Labrador, Canada are illustrated. Problems concerning genus-level diagnostic characters for Acentrella nymphs and adults are discussed to facilitate placement of future taxa. To complement existing keys to Nearctic nymphs of Acentrella a provisional key to the known adult males is given."
Jacobus,LM and McCafferty,WP 2006 A new species of Acentrella Bengtsson (Ephemeroptera: Baetidae) from Great Smoky Mountains National Park, USA. Aquatic Insects 28:101-111. PDF
They describe a new species (Acentrella barbarae) and provide a key to the larvae of the seven North American Acentrella species.
Kendrick,MR; Huryn,AD; Bowden,WB; Deegan,LA; Findlay,RH; Hershey,AE; Peterson,BJ; Beneš,JP and Schuett,EB 2018 Linking permafrost thaw to shifting biogeochemistry and food web resources in an arctic river. Global Change Biology, 24(12), pp.5738-5750. PDF
Quote from page :"Bulk δ13C composition of larval Acentrella, Simuliidae, and Orthocladius, but not the biofilms upon which they feed, decreased significantly from 1986 to 2011 (Figure 6). Carbon isotopic values of epilithic biofilms were -29.2‰, -30.4‰, and -31.0‰ for 1986, 1998, and 2011, respectively. Changes in δ13C composition of Acentrella, Simuliidae, and Orthocladius were evident among aquatic insects collected, dried and analyzed in 1986, 1998, and 2011. Similar changes were found for Acentrella and Simuliidae regardless of whether samples had been preserved in 70% ethanol, or 4% formaldehyde (Table S4).
The δ13C value for the phospholipid fatty acids recovered from a pooled 2011 biofilm sample was -36.35‰ (calculated as a weighted average of the individual fatty acids), which was 5.35‰ more depleted than the biofilm δ13C bulk composition (Table S5, S6). Similarly, comparisons of Acentrella and Simuliidae phospholipid fatty acids were 4.4‰ and 2.6‰, respectively, more depleted than their corresponding δ13C bulk composition. These values are well within the range of observed depletion of lipids compared to bulk samples. Analysis of the neutral lipid fatty acid profiles of Acentrella, Simuliidae, and Orthocladius indicated that all consumed food resources containing bacteria and microeukaryotes. A comparison of the δ13C value for individual biofilm phospholipid fatty acids to those of Acentrella and Simuliidae neutral fatty acids found that neutral lipid fatty acids of Acentrella were depleted in 13C compared to biofilm phospholipid fatty acids (3.72 ± 2.83‰, n = 10), while little difference between Simuliidae neutral fatty acid δ13C values compared to biofilm phospholipid fatty acid values was found (-1.93 ± 2.33‰, δ13CPLFA-Biofilm - δ13CNLFA - Simuliidae, n = 8). A comparison of the δ13C value for individual tube-associated phospholipid fatty acids that serve as the putative food source for Orthocladius to those of Orthocladius neutral fatty acids found that neutral lipid fatty acids of Orthocladius were depleted in 13C compared to tube-associated phospholipid fatty acids (2.53 ± 1.53‰, n = 4). These results show that Simuliidae reflect broad similarity to epilithic biofilms (and relatively minor changes in temporal isotopic patterns), whereas the isotopic composition of fatty acids in Acentrella and Orthocladius tissues reflect more selective feeding strategies. Furthermore, young of the year Thymallus arcticus appear to be feeding on a diet more enriched in 13C than grazing insects and more similar to δ13 C values shown for Simuliidae (Table S6)."
Kluge,NJ and Novikova,EA 2011 Systematics of the mayfly taxon Acentrella (Ephemeroptera: Baetidae), with description of new Asian and African species. Russian Entomological Journal 20(1) 1-56.PDF
Lugo-Ortiz,CR and McCafferty,WP 1998 A new North American genus of Baetidae (Ephemeroptera) and key to Baetis complex genera. Entomological News 109 (5) 345-353. PDF
McCafferty,WP and Waltz,RD 1990 Revisionary synopsis of the Baetidae (Ephemeroptera) of North and Central America. Transactions of American Entomological Society 116, 769-799. PDF
Waltz,RD 1994 Field recognition of adult Acentrella and Heterocloeon (Ephemeroptera: Baetidae). Great Lakes Entomologist 26(4):321-323.
The author shows that adult Acentrella and Heterocloeon have an anterior process on their mesothorax. This is distinctive for these two genera. Or in plain english, Acentrella adults have a bump on their back just in front of their wings, which is not present in any other local adult mayflies.
Waltz,RD and McCafferty,WP 1987 Systematics of Pseudocloeon, Acentrella, Baetiella, and Liebebiella, new genus (Ephemeroptera: Baetidae). Journal of the New York Entomological Society 95:553-568.
Wang,TQ and McCafferty,wp 1996 New diagnostic characters for the mayfly family Baetidae (Ephemeroptera). Entomological News 107 2, 207-212. PDF
Wilson,MJ; McTammany,ME and Bohr,HR 2019 Manganese oxides as localized drivers of benthic invertebrate density and community structure. Hydrobiologia, 838, pp.85-98. PDF
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