*SHOW ~ British Entomology - The genera of Ephemeroptera. 19 August 
2003.
*COMMENT MJD 9/8/2018. Minor changes.
 
*CHARACTER LIST 
 
#1. <synonyms:>/
 
#2. <sex of imago>/
       1. male/
       2. female/
 
#3. the compound eyes <of imagines, separation>/
       1. contiguous/
       2. widely separated/
 
#4. the compound eyes <of imagines, two-lobed or not>/
       1. distinctly two-lobed <the larger, upper lobe usually with
          larger facets than those of the lower, in which they are
          usually darker>/
       2. rounded <not lobed, though sometimes two-coloured>/
 
#5. the upper lobe <of the compound eyes of imagines, whether
          turbanate>/
       1. turbanate <turban-shaped>/
       2. rounded/
 
#6. second antennal segment <of imagines and sub-imagines, relative
          length>/
       1. three times as long as the first/
       2. no more than twice as long as the first/
 
#7. wings <whether fringed>/
       1. fringed in the imago <Caenidae only>/
       2. fringed only in sub-imagines <implicit>/
 
#8. wings <of imagines and sub-imagines, spotted or unspotted>/
       1. more or less spotted with brown or blackish/
       2. unspotted <dubiously implicit>/
 
#9. fore-wings <of imagines and sub-imagines, whether veins M1 and Cu1
          are strongly divergent>/
       1. with veins M1 and Cu1 strongly strongly diverging basally/
       2. with veins M1 and Cu1 sub-parallel basally <implicit>/
 
#10. fore-wings <of imagines and sub-imagines, whether veins R4 and R5
          detached>/
       1. with R5 detached basally from R4/
       2. with R5 and R4 joined basally <implicit>/
 
#11. the marginal fore-wing veinlets <of imagines and sub-imagines,
          whether single or paired between the main longitudinal
          veins>/
       1. single/
       2. paired/
 
#12. hind-wings <of imagines, present or absent>/
       1. present <though sometimes very reduced>/
       2. absent <even as vestiges>/
 
#13. the hind-wings of the female imagines <length relative to
          fore-wings: data recorded only for two-tailed females!>/
       1. no more than one fifth the length of the fore-wings/
       2. more than one fifth the length of the fore-wings/
 
#14. the hind-wing costa <of imagines and sub-imagines, smoothly
          curved or with a projection>/
       1. smoothly curved/
       2. with a conspicuous projection/
 
#15. the fore-legs <of imagines, insertion close or distant>/
       1. inserted relatively close together under the thorax/
       2. widely separated under the thorax/
 
#16. hind tarsi <of imagines and sub-imagines, length relative to the
          tibia>/
       1. about one-and-a-half times the length of the tibia
          <Siphlonurus>/
       2. slightly shorter than the tibia <Ameletus>/
 
#17. hind tarsi <of imagines and sub-imagines, number of moveable
          segments>/
       1. with 5 moveable segments/
       2. with 4 moveable segments <the fifth, if present, fused to
          the tibia>/
       3. with 2-3 moveable segments/
 
#18. the first segment of the hind tarsus <of imagines, length
          relative to the second segment>/
       1. about twice as long as the second/
       2. about three times as long as the second/
 
#19. the hind tarsal claws <of imagines, whether both pointed or one
          blunt and one pointed>/
       1. both pointed/
       2. unalike, being one pointed and one blunt/
 
#20. the abdomen <of imagines, number of tails>/
       1. with two tails/
       2. with three tails/
 
#21. male claspers <crossed or separate>/
       1. crossed/
       2. separate/
 
#22. the lobes of the penis <broad or narrow>/
       1. very broad-tipped, and closely approximated/
       2. narrow, rod-shaped, and widely separated/
 
#23. the lobes of the penis <appendages/spurs>/
       1. each with one recurved appendage <spur>/
       2. each with two recurved appendages <spurs>/
       3. without recurved appendages/
 
#24. the outer tails <of nymphs, distribution of hairs>/
       1. hairy <bearing long hairs> on the inner side only/
       2. hairy on both sides/
 
#25. gills <of nymphs, position on abdomen>/
       1. mostly at the sides of the abdomen/
       2. mostly lying on the upper surface of the abdomen/
 
#26. gills <of nymphs, fringing>/
       1. all densely fringed with filaments on both sides/
       2. not fringed with filaments on both sides/
 
#27. gills <of nymphs, whether consisting of a plate with a tuft of
          filaments>/
       1. mostly consisting of a plate bearing a tuft of filaments/
       2. never comprising a plate bearing a tuft of filaments/
 
#28. superfamily/
       1. Ephemeroidea/
       2. Baetoidea/
       3. Heptagenioidea/
 
#29. family/
       1. Baetidae/
       2. Caenidae/
       3. Ephemeridae/
       4. Ephemerellidae/
       5. Heptageniidae/
       6. Leptophlebiidae/
       7. Potamanthidae/
       8. Siphlonuridae/
 
#30. <number of species in Britain and Ireland>/
       species/
 
#31. <species list for Britain and Ireland, with binomials and anglers colloquial
          names>/
 
#32. <abbreviated taxon name:>/
 
#33. <illustrations:>/
