(Panephemeroptera Euephemeroptera Euplectoptera Anteritorna Bidentiseta Furcatergaliae  
Fimbriatotergaliae Caenotergaliae Caenoptera Caenis/f3=g1Caenis/f4=g2

Nomen hierarchicum: Caenis/f4=g2 [f:1853; g:1835]  (sine Madecocercus; incl. Tillyardocaenis)

In circumscription fits:

 subfam. Caeninae: Malzacher 1997: 551

 Caenis/f4=g2: Kluge 2004: 286

References. Needham & Traver & Hsu 1935: * *; Edmunds & Jensen & Berner 1976: * *; Malzacher 1997: * *; McCafferty & Wang 2000: * *; Kluge 2004: * * * *

Autapomorphies of Caenis/f4=g2.

(1) Imaginal, subimaginal and larval prosternum is narrow, bases of fore legs are brought together; in imago and subimago prosternum has more or less triangular or trapezoid shape, strongly narrowing anteriorly (Malzacher 1995: Fig.26; Kluge 2004: Fig.86:B).

Non-unique character, but differs from Brachycercus/f1=g3 and Madecocercus, where prosternum is wider and rectangular.

(2) Imaginal metanotum [vestigial see Caenoptera (9)] has posterior border of scutellum bent up, thus area behind it is exposed dorsally, and this border looks as a transverse ridge on dorsal side of metanotum (Kluge 2004: Fig.87:A-B). At the same time, larval and subimaginal metanotum retains primitive structure flat, with prominent scutellum projected posteriorly.

Character of Caenis/f4=g2 of unclear phylogenetic status. 

(3) Larval claws usually with 1 row of denticles on inner margin (in some species these denticles are very small or absent). Non-unique apomorphy (see Index of characters [1.2.21]); other Fimbriatotergaliae have no denticles on claws.

Size. Fore wing length 28 mm.

Distribution. World-wide.

The taxon Caenis/f4=g2 is divided into:

1. plesiomorphon Tillyardocaenis

2. Caenis/f5=g3

2.1. plesiomorphon Caenis/f6=g4

2.2. Brasiliocaenis

2.3. Clypeocaenis/g1

2.3.1. plesiomorphon Amercaenis

2.3.2. Clypeocaenis/g2 plesiomorphon Barnardara Clypeocaenis/g3

2.4. Caenopsella/g1

2.4.1. plesiomorphon Afrocaenis

2.4.2. Caenopsella/g2

Some taxa, known as larvae only, have uncertain position