2 



- 



f- 



to be 8 or less longitudinal veins; cross venation 



greatly reduced OLIGONEURIINAE 



Fore wing with more extensive venation than above 



2 



First anal vein of fore wing ends in outer margin; no 



cubital intercalaries BAETISCINAE 



First anal vein ends in hind margin; cubital inter- 

 calaries present 3 



Hind wings present or absent; outer fork of Rs (Of) of 

 fore wing and posterior branch of M detached basal ly 

 from their respective stems (fig. 3:106); eyes of male 



turbinate : BAETINAE 



Hind wings present or absent; Of of fore wing attached 



basally; eyes of male not as above 4 



Hind wings absent in imago; posterior branch of M in 

 fore wing may be attached or detached basally from 



anterior branch (fig. 3:10a) CAENINAE 



Hind wings present; posterior branch of M in fore wing 



normal, attached basally to anterior branch 5 



Of of hind wing (R 4 and R 5 ) present; tails 2 6 



Of of hind wing absent; tails 3 7 



Cubital intercalaries of fore wing consist of a series 

 of forking or sinuate veinlets attaching Cu, to hind 



margin (fig. 3:2a) SIPHLONURINAE 



Cubital intercalaries of fore wing 2 to 4 in number, free 



basally, not as above METRETOPINAE 



Two pairs of cubital intercalaries, the anterior pair 

 being the longer; first anal vein of fore wing attached 

 to hind margin by a series of veinlets 



AMETROPINAE 



Two cubital intercalaries only; first anal vein not 



attached to hind margin as above 8 



Two short intercalaries in fore wing between median 

 intercalary and posterior branch of M, also between 

 the latter vein and Cu,; male forceps with a single 

 short terminal joint (fig. 3:11a) . . . EPHEMERELLINAE 

 No true intercalaries in fore wing in positions indicated 

 above; male forceps with 2 (occasionally 3) short ter- 

 minal joints (fig. 3:10c) LEPTOPHLEBIINAE 



Nymphs 



Gills of the first abdominal segment stem from the 

 ventral surface; a tuft of gills at the base of each 



maxillae, but no gill tufts at base of fore coxae 



OLIGONEURIINAE 



Gills of the first abdominal segment not as above; gill 

 tufts at base of maxillae may be present when accom- 

 panied by gill tufts at the base of the fore coxae .... 2 

 Gills completely concealed beneath an enormously 

 enlarged thoracic shield or carapace . . . BAETISCINAE 



Gills exposed; thoracic notum normal 3 



Outer tails fringed 2 on both sides 4 



Outer tails with heavy fringes on inner side only (may 



have a few short hairs on outer side) 6 



Gills present on abdominal segments 1-7 



LEPTOPHLEBIINAE 



Gills absent from one or more of segments 1-7 5 



Gills present on segments 3-7 or 4-7; in latter case, 

 may be elytroid on segment 4; a rudimentary gill often 



present on segment 1 EPHEMERELLINAE 



Gills present on segments 1-6 or 2-6; if present, rudi- 

 mentary on segment 1; gill on segment 2 elytroid, cover- 

 ing all those behind it CAENINAE 3 



Claw of fore leg usually differs from others in structure 

 but, if similar in structure, margins of gills deeply 

 fissured; claws of middle and hind legs long and 



slender 7 



Claws on all legs similar, sharp pointed, and usually 



89 

 Day: Ephemeroptora 



"much shorter than tibiae; mar^n* of glllfl nut fissured 

 S 



7. Claw of fore leg bifid METRETOPINAE 



— Claw of fore leg sometimes slender, ourved, bearing 

 several long spines; when for.- olaw without i u< I. 

 spines, gills deeply fissured AMETROPINAE 



8. Posterolateral angles of the aploal abdominal 'i-m. ni 

 prolonged into thin, flat lateral A margin 

 of labrum usually with not more than a .-shallow, broad 

 emargination SIPHLONURINAE 4 



— Posterolateral angles of apical abdominal 



hardly more than acute, not prolonged into flat, thin, 

 lateral spines; a well-defined notch at center of frontal 

 margin of labrum BAK I IN \\ 



Subfamily SIPHLONURINAE 



Key to the Genera 



Adults 



1. Claws on each tarsus dissimilar; costal angulation of 

 the hind wing acute (fig. 3:116) Ameletus Eaton 



— Claws on each tarsus similar; costal angulation of hind 

 wing obtuse or wanting 2 



2. Hind tarsus longer than tibia (except in Siphlonurus 

 marshalli); all claws sharp pointed (fig. 3:2a) 3 



— Hind tarsus shorter or subequal to tibia; claws of 

 middle and hind legs sharp pointed, variable on fore 

 leg of male 4 



3. Fore leg as long or longer than body; posterior margin 

 of styliger plate of male produced, straight, or slightly 

 concave Siphlonurus Eaton 



— Fore leg two-thirds the length of the body; posterior 

 margin of styliger plate of male with deep, median 

 V-shaped cleft (fig. 3:27a) Edmundsius Day 



4. Abdominal segments 5-9 dilated laterally into flat, 

 broad expansions; no costal angulation on hind wing 



Siphlonisca Needham 



— Abdominal segments 5-9 not dilated as above; costal 

 angulation of hind wing present 5 



5. Media of hind wing simple, not forked; all claws sharp 

 pointed Parameletus Bengtsson 



— Media of hind wing forked near outer margin (fig. 3:2d); 

 fore claws of male similar, blunt, in most species .. . 



Is onychia Eaton 



Nymphs 



1. Fore legs conspicuously fringed with long hairs (fig. 

 3:11/); gill tufts present on bases of maxillae and fore 

 coxae Isonychia Eaton 



— Fore legs without such conspicuous fringes; no maxil- 

 lary or coxal gill tufts 2 



2. Gill lamellae double on at least segments 1 and 2 . . 3 



— Gill lamellae single on all segments 4 



3. Gills oval, the posterior lamellae on segments 1 and 2 

 about two-thirds as large as the anterior lamellae (fig. 

 3:27g); meso- and metathoracic claws almost twice as 

 long as the prothoracic claws Edmundsius Day 



— Gills with retuse apical margins, the posterior lamellae 

 on segments 1 and 2 as large as the anterior lamellae 

 (fig. 3:llc,d); meso- and metathoracic claws not notice- 

 ably longer than the prothoracic claws 



Siphlonurus Eaton 



Baetodes of subfamily Baetinae with tails almost bare. 



Neoephemera of the family Ephemeridae has similar characters 

 but differs in having buds and tiny gills on segment 1; in the 

 Caeninae, hind wing buds are usually lacking but, if present, 

 gills are lacking entirely on segment 1. 



4 In Parameletus and some species of Ameletus, these spines 

 are very short and weakly developed. The pincerlike process at 

 the tip of the labial palp in Parameletus and the series of pecti- 

 nate spines on the crown of the maxilla in Ameletus easily 

 separate these 2 genera from all of the Baetinae. In Edmundsius 

 the frontal margin of the labrum is broadly and rather deeply 

 excavated. 



s In Apobaetis, frontal margin of labrum without center notch. 



