Canadian Journal of Arthropod Identification

The Taxonomy of the North American Species of Parameletus Bengtsson, 1908 (Ephemeroptera: Siphlonuridae), with Keys to Nymphs and Male Imagos

CJAI 33 -- November 1, 2017

Steven K. Burian

| Abstract | Introduction | Materials & Methods | Key to Parameletus species | Systematic Accounts | Acknowledgments | References | PDF | Cite | Appendix |


Materials & Methods

Although it would have been desirable to obtain new reared material for all Nearctic Parameletus species, unfortunately this was not possible because of the difficulty in obtaining live nymphs for rearing. Parameletus midas was the only species for which a new series was obtained. Live nymphs of P. croesus were collected by Brigid O’Donnell in 2007 from Wisconsin, but she was unable to fully rear these specimens. Although none of O’Donnell’s specimens fully emerged, one final instar male nymph was positively associated with the male imago of P. croesus. The association was made by the recognition of diagnostic characters of the male imago on the developing subimago visible through the cuticle of the last instar nymph, hence a complete association between the nymph and imago stage. Unequivocal diagnostic characters were the dark medial marks on the abdominal sterna of the male imago and the deep v-notched styliger plate. These characters were unmistakable through the nymphal cuticle and provide the same level of primary evidence of immature-adult association as if the specimen had fully emerged. Therefore it was not considered to be a tentative association. In addition, there were other secondary lines of evidence to support the association. First, nymphs of all other species of Nearctic Parameletus were known and morphological study of all nymphs from Wisconsin showed that they were different from those associated with all other known North American species. Second, no adults of any species except P. croesus have ever been collected in the region of Minnesota and Wisconsin. Third, all specimens of Parameletus nymphs studied from Wisconsin are morphologically congruent with the nymph associated by adult diagnostic characters to be that of P. croesus. Finally, with the intensity of entomological studies conducted in Wisconsin over the past 63 years by some of the most experienced aquatic entomologists in the United States (e.g., William Hilsenhoff), it is highly unlikely that if a different species of Parameletus was present that they would have failed to have found it (even if they didn’t know what it was). All of these lines of evidence taken together strongly support the conclusion that all nymphs deemed morphologically congruent with the one specimen which was positively associated with the adult stage of P. croesus (by observation of adult diagnostic characters) were the nymphs of P. croesus.
Live nymphs of P. midas were collected from the Dead River, Maine, USA using a standard D-frame kick net, transferred to 500 ml plastic jars containing stream water from the collections site. Jars were aerated and slightly chilled for transport to the laboratory. In the laboratory nymphs were placed in large circular glass culture dishes (dia. ~ 23 cm) with emergent vegetation from the field site. Emergent vegetation placed in rearing dishes provided a natural surface for the final instar nymphs to crawl up (as do other siphlonurids) at the time of emergence. Each rearing dish was aerated with a small airstone and covered with a self-supporting domed mesh enclosure that allowed space for subimagos to fly away from the water. Water temperature in rearing dishes was maintained as close to 17°C as possible (field water temperature where black wing pad nymphs were collected ranged from 16.9–17.4°C). Subimagos were removed upon emergence to subimago boxes to make the final molt and associated nymphal exuviae were preserved in 80% alcohol and kept with each subimago until it molted. Imagos were preserved in 80% alcohol with the associated nymphal exuviae.
All specimens were observed for morphological characters, coloration, and color patterns under stereoscopic and compound light microscopes (up to 1000x magnification). Mouth and body parts of the nymphs were dissected in 80% alcohol and slide mounted in Hoyer’s Mounting Media or Euparal®. Male genitalia were slide mounted for study and examined intact. Study of intact genitalia is important because subtle and membranous features are highly susceptible to distortion during and after slide mounting. Some of the type material was slide mounted by the original authors and studied in that form. Imago wings were also examined and measured intact. Standard terminology for adult anatomy and morphology was used (Kluge 1994). Standard terminology for nymphs given by Kluge et al. 1995 was used except for the names given to sclerotized supports for abdominal gills. All abdominal gills of Parameletus nymphs have a sclerotized ventral strip with setae and a sclerotized mid-rib. These structures are identified as the fore costa (FC–ventral strip) and hind costa (HC–mid rib) by Kluge et al. 1995, but because of the similarity between these terms and the well-established name of the primary wing vein “costa” I have elected not to use them to avoid any confusion. The abbreviation PLPs is used to refer to the posterolateral projections of abdominal terga of nymphs and where necessary of a specific tergite (e.g., PLPs-tergite IX). Tarsal segments of legs of imagos are abbreviated as an uppercase “T” and a subscript denoting a specific segment number or range of segments (e.g., T1 refers to tarsal segment 1). In the materials studied and appendix sections the abbreviation Nex refers to shed nymphal exuviae. Specimens were photographed using a Nikon D300s DSLR and the Nikon Camera Control Pro2® software. All measurements were made using a calibrated ocular micrometer (nearest 0.10 mm). Measurements were made from entire specimens and/or parts (not mounted on slides) that were held as flat as possible (without inducing distortion) using sections of broken glass microscope slides and coverslips. Conventions for standard measurements described by Hubbard (1995) were followed. Means and standard deviations (abbreviated as SD) were calculated for all continuous data. Lengths of the foreleg segments of the male imago were standardized to the length of the foretibia and expressed as ratios. These values represent percentages relative to the length of the foretibia. Description of colors and hues were kept as simple as possible with regard to common and standard color names. Eggs were dissected from a reared female imago in 80% alcohol. Eggs were carefully removed from the lower oviduct (to minimize differences possibly related to maturation) with a 2 µl adjustable micropipette, dehydrated in 100% propanol for 10 min. and mounted in Euparal®. Chorionic features of eggs were observed under phase contrast microscopy (400 and 1000x).
Although not comparable, basic descriptions of male imagos of P. chelifer, P. columbiae, P. croesus, and P. midas are available (McDunnough 1923, 1938, Traver 1935, Söderstrom and Nilsson 1986, and Tiunova 2008). For the 3 strictly North American, species adult descriptions have focused mostly on aspects of color and color patterns of male and female imagos. In addition, most of these descriptions were composed using terminology and color descriptions that are antiquated and difficult to interpret. To facilitate a clear and unambiguous understanding of these taxa new comparable descriptions using standard terminology and updated species diagnoses (with new figures) and morphometric data are presented here. Where possible specimens believed to show the least effects of long-term preservation in alcohol were used for descriptions and diagnoses. New comparative descriptions (with new figures) are presented for near final instar nymphs.
Specimen abbreviations and symbols: ♂ = male imago; ♀ = female imago; S♂ = male subimago; S♀ = female subimago; N♂ = male nymph; N♀ = female nymph; Nex = nymphal exuviae; CNC = Canadian National Collection, Ottawa, Ontario, Canada;  CSU = Colorado State University, C.P. Gillette Museum of Arthropod Diversity, CO, USA;  FAMU = Florida A&M University, Tallahassee, FL, USA; FLBS = Flathead Lake Biological Station Collection, University of Montana, Polson, MT, USA; ILNHS = Illinois Natural History Survey Insect Collection, Champaign, IL, USA; MEIFW = Maine Inland Fish & Wildlife, Bangor, ME (specimens from this source deposited with author); NEL = Northeast Ephemeroptera Laboratory, Department of Biology, Southern Connecticut State University, New Haven, CT, USA; PERC = Purdue Entomological Research Collection, Purdue University, West Lafayette, IN, USA; SWRC = Stroud Water Research Center, Avondale, PA, USA; UAM = University of Alaska Museum of the North, University of Alaska, Fairbanks, AK, USA; UM = University of Minnesota Insect Collection, University of Minnesota, St. Paul, MN, USA; USGS-NAWQA = United States Geological Survey, National Water Quality Assessment Program, National Water Quality Laboratory, Denver, CO, USA; WDNR = Wisconsin Department of Natural Resources, Ecological Inventory and Monitoring, Superior, WI, USA. Deposition of all specimens is with the institutions listed for each record. Latitude and longitude coordinates are given, where possible, in positive and negative decimal degree format. In some instances because of vague or incomplete original locality information coordinate pairs for a site were estimated using all available descriptive location data combined with remote inspection of general vicinity of sampling area using satellite imagery and information on the circumstances under which a sample was obtained. These estimates are denoted by an (*). All georeferenced specimen data for material studied are presented in a separate excel spread sheet (Append. 1) to facilitate use of these data in mapping programs and future biodiversity analyses. A separate excel spread sheet page is also provided for all records of Nearctic Parameletus previously published so these data can also be used for geo-spatial study (Append. 1). The literature cited section of the paper includes references for previously published records that occur in Append. 1. Species distribution maps were prepared using Simplemappr® (Shorthouse 2010).

Material Studied

Parameletus chelifer Bengtsson, 1908
Material Examined. CANADA: Northwest  Territories: Horton River, Site 14 [68.47541N/ -128.634278W], D. Giberson, 23 Jul 2000, 1♂, 1♀ [NEL]; Horton River, Site 14 [68.47541N/ -128.634278W], D. Giberson, 24 Jul 2000,  5♂ [NEL]; Horton River, Site 29 [69.049639N/ -126.184833W], D. Giberson, 31 Jul 2000, 1♂,1♀ [NEL]; same, (PERC No. 0064691], same, 2♂, [PERC]; Thelon River, trib., Site 19 [64.179472N/ -102.616139W], D. Giberson & L. Purcell, 6 Jul 2002, 17N [NEL]; Thelon River, trib., Site 22 [64.184833N/ -102.318583W], D. Giberson & L. Purcell, 7 Jul 2002, 15N [NEL]; Tundra pond above Thelon River Site 27 [64.320333N/ -101.836417W], D. Giberson & L. Purcell, 8 Jul 2002, 26N [NEL]; Nunavut: Maguse River north of Arviat, swift flowing large river [61.298883N/ -94.080183W], D. Giberson, 10 Jul 2003,  1S♂, 1♀ [NEL]; Baker Lake, airport road, small pond at campground [64.315617N/ -96.053967W], D. Giberson, 14 Jul 2003, 14N [NEL]; USA: Alaska: Yukon-Koyukuk Co., Fort Yukon, above Arctic Circle [66.565367N/ -145.278597W*], C.W. Pagel,  17 Jul 1965, 1♂ [NEL]; Fairbanks North Star Co., Chatanika River, puddle near Elliot Hwy bridge, (UAM No. 50463) [65.084459N/ -147.725698W*], Sch. & Berg.(?), 6 Jun 1977, 2N [UAM]; Chatanika River, old channel (UAM No. 50467)  [65.086376N/ -147.738764W*], Sch. & Berg. (?), 12 Jun 1973, 1N [UAM]; Chatanika River, old channel (UAM No. 50466) [65.086376N/ -147.738764W], Sch. & Berg.(?), 12 Jun 1973, 1N [UAM]; Chatanika River, old channel (UAM No. 50464) [65.095946N/ -147.680510W*], Sch. & Berg. (?), 23 Jun 1976, 15♀ [UAM]; Chena River, 2nd bridge (UAM No. 50484) [64.848259N/ -147.383583W*], Jink & Berg., 14 Jun 1972, 2♂ [UAM]; Salcha River, pipeline x-ing (UAM No. 50453) [64.485201N/ -146.663052W*], Sch. & Berg. (?), 22 Jun 1972, 1♂ [UAM]; Bethel Co., Holitna River (UAM No. 50458) [61.635231N/ -157.115829W*], Gar. & Berg. (?), 11 Jun 1976, 1♂ [UAM]; Holitna River (UAM No. 50461b) [61.635231N/ -157.115829W*], Gar. & Berg. (?), 26 Jun 1977, 1♂ [UAM]; Holitna River (UAM No. 50455) [61.635231N/ -157.115829W*], Gar. & Berg. (?), 30 Jun 1977, 1♂ [UAM]; Holitna River (UAM No. 50457), [61.635231N/ -157.115829*], Gar. & Berg. (?), 17 Jul 1977, 1♂ [UAM]; North Slope Co., Umiat, small rock bottomed stream, elev. 352’ (PERC No. 0064686), [69.367277N/ -152.1416W*], C.M. White, 17 Jun 1964, 15N, [PERC]; SWEDEN: Abisko (estimated site edge of lake at Abisko–PERC No. 0064687) [68.354888N/ 18.840431E], Thienemann ? Jun 1936, 3N, 1Nex, [PERC].

Parameletus columbiae McDunnough, 1938
Material Examined. Holotype, CANADA: British Columbia: Thompson-Nicola Co., Dunn Peak, North Thompson River, swarm over small glacial stream at 7000 ft. elev., (CNC No. 4289) [51.441757N/ -119.954675W*], J.K. Jacob, 10 Aug 1937, 1♂ [CNC].
Other Material Studied. USA: Alaska: Fairbanks North Star Co., Chatanika River, 0.8 miles below x-ing (13:00–14:00 hr.) sample C-B (UAM No. 50485) [65.081917N/ -147.734134W*], 12 Apr 1978, 3N [UAM]; Chena River, C-750, Qual. (UAM No. 50456) [64.848259N/ -147.383583W*], Sch. & Jin. (?), 8 May 1972, 20N [UAM]; Chena River, C-800, Qual. (UAM No. 50454) [64.848259N/ -147.383583W*], Sch. & Jin. (?), 8 May 1972, 1N [UAM]; Chena River, C-725, Qual. (UAM No. 50452) [64.848259N/ -147.383583W], Sch. & Jin.(?), 8 May 1972, 20N [UAM]; Bethel Co., Holitna River (UAM No. 50461a)  [61.635231N/ -157.115829W*], Gar. & Berg. (?), 26 Jun 1977, 1♂ [UAM];  Holitna River (UAM No. 50460) [61.635231N/ -157.115829W*], Gar. & Berg. (?), 29 Jun 1977, 1♂ [UAM]; Holitna River (UAM No. 50459) [61.635231N/ -157.115829W*], Gar. & Berg. (?), 19–20 Jun 1976, 1♀ [UAM]; Idaho: Latah Co., 6 mi. north of Harvard (PERC No. 0064689) [46.982101N/ -116.670398W], G.B. White, 12 Jun 1964, 31♀ [PERC]; same, (PERC No. 0064688), same, 11♀ [PERC]; Montana: Flathead Co., Temporary pond at Nyack [48.439617N/ -113.804938W*], S. Chilcote, 13 Jun 2002, 5N [FLBS]; Small stream N. of 2-Lakes Creek, Gunsight Lake Trail, Glacier National Park       [48.655035N/ -113.662708W*], N.P. Colager (?), 19 Jul 1997, 7♂, 4♀ [FLBS]; Utah: Salt Lake Co., Brighton, Silver Lake [40.603466N/ -111.588268W*], G.F. Edmunds Jr., 2 Jun 1947, 3N [FAMU]; same  (ILNHS No. 12373), 23 Jun 1947, 1♂ [ILNHS]; same (ILNHS No. 12373), 2 Jun 1947, 17N [ILNHS].

Parameletus croesus (McDunnough, 1923)
Material Examined. Holotype, CANADA: Ontario: Ottawa Division, Ottawa (CNC No. 522) [45.389755N -75.711848W*], J.H. McDunnough, 22 May 1922, 1♂ [CNC].
Other Material Studied. USA: Minnesota: Pine Co., St. Croix River, at ferry between Pine City, MN and Grantsburg, WI [45.823431N/ -92.764246W], R.H. Daggy, 26 May 1939, 8♂ [UMN]; Wisconsin: Marinette Co., Menominee River, right bank, about 85ft dnstr. from Hwy JJ bridge and ~2.9 miles dnstr. of Grand Rapids Dam [45.325784N/ -87.663235W*], S. Rheaume, 23 May 1995, 2N [USGS-NAWQA]; same, B. O’Donnell, 13 May 2007, 8N [NEL]; Burnette Co., St. Croix River, Seven Islands, 0–3ft. depth, swift, sand, & gravel [45.83979N/ -92.750617W*], R.A. Lillie, 6 May 1992, 1N [WDNR]; same, St. Croix River, Seven Islands, drop-off, sand, rock, debris, 12492018 (PERC No. 0064690), same, 1N [PERC]; Outagamie Co., Wolf River, Shiocton, below Hwy  54 [44.44283N/ -88.588162W*], R.A. Lillie, 6 May 1993, 1N [WDNR]; same, 011994047-89 (PERC No. 0064685) same, 7N [PERC].

Parameletus midas (McDunnough, 1923)
Material Examined. Holotype, CANADA: Ontario: Ottawa Division, Ottawa (CNC No. 523), [45.389755N -75.711848W*], J.H. McDunnough, 29 May 1922, 1♂ [CNC]; Paratype, Ontario, Ottawa Division, Ottawa (CNC No. 523) [45.389755N/ -75.711848W*], J.H. McDunnough, 29 May 1922, 1♂ [CNC].
Other Material Studied. CANADA: New Brunswick: Gloucester Co., Nepisquit River, Hwy 360 (Middle Landing)  [47.440943N/ -65.705252W*], B. Kondratieff & R. Bauman, 17 Jun 1993, 1♂ [CSU]; Newfoundland (Labrador): Minipi Drainage, L4 [52.604899N/ -61.162381W*], D. Larson & D. Butt, 26 Jun 1983, 3N [NEL]; same, 28 Jun 1983, 2N [NEL]; Quebec: Minganic, Côte-Nord Region, Thunder River (Rivière-au-Tonnerre)[50.28091N/ -64.74834W*], W.J. Brown, 16 May 1930, 3♂ [CNC]; same, 19 Jun 1930, 4♂(reared), 4♀ [CNC]; same, 19 Jun 1930, 5♂ [CNC]; same, 19 Jun 1930, 8Nex [CNC]; same, 21 Jun 1930, 1♂ [CNC]; same, 23 Jun 1930, 5♂ [CNC]; Saquenay, Rivière Pigou, above Tr. 138, elev. 075 ft AMSL [50.2825N/ -65.641944W], D.H. Funk, 6 Jul 1984, 1S♂, 1Nex [SWRC]; USA: Maine: Aroostook Co., Machias River, Site 26 [46.5348N/ -68.6128W],  M. Duron & M. Neal, 29 May 2004, 1N [MEIFW]; Machias River, sedge meadow within 1 mile below Grassy Landing (T10 R7 Wels/ T11 R7 Wels) [46.557908N/ -68.592197W], B. Swartz,  8 Jun 2005, 1N [MEIFW]; Franklin Co., South Branch Dead River, Eustis (UTM 19T 0384938 5001167)  [45.154645N/ -70.463786W], M. Seibenmann, 3 Jun 2009, 11N [NEL]; South Branch Dead River, Eustis, cove on north shore nr. Cove Brk., north of Stratton, elev. 351 m [45.154583N/ -70.463767W], S.K. Burian, 30 May 2008, 1S♂,3 S♀, 2Nex [NEL]; same, 30 May 2008, 20♂,28♀, 7S♂, 11 S♀ 13N, 61Nex [NEL]; Washington Co., Narraguagus River, Rt. 9 [44.842212N/ -68.069674W*], B. Kondratieff & R. Bauman, 2 Jun 1998, 1♂ [CSU].