(Panephemeroptera Euephemeroptera Euplectoptera Anteritorna INCERTAE SEDIS)

Nomen hierarchicum: Hexagenites/fg1 [f:1917; g:1880] 

In circumscription fits:

subfam. Ephemeropsinae Cockerell 1924: 136

fam. Hexagenitidae: Tshernova 1961: 589

Hexagenites/fg1: Kluge 2004: 353

Synonyms: subjective synonyms of Hexagenites/fg (typus weyenberghii [H.]) with conspecific type-species:

Paedephemera/fg [f:1917; g:1906] (typus multinervosa [Ephemera])

Stenodicranum/fg [fg: 1954], typus cellulosa [Ephemera])

(subjective synonymy: cellulosa [E.] = weyenberghii [H.] = multinervosa [E.] (Demoulin 1970c: 7)

Nominal taxa included:

Ephemeropsis/fg [f:1924; g:1864] 

Phacelobranchus/g [g:1906]

Protoligoneuria/g [g:1955]

Hexameropsis/g [g:1974] 

Libanoephemera/g [g:2019]

Mongologenites/g [g:1986] 

Palaeobaetodes/g [g:1987] 

Cratogenites/g [g:1996]

Cratogenitoides/g [g:1996]

Cratohexagenites/g [g:2007]

Caenoephemera/g [g:2001] 

Shantous/g [g:2007]

Epicharmeropsis/g [2007]

Possibly, here also belongs Costalimella (see Euplectoptera incertae sedis).

References. Cockerell 1924: ; Tshernova 1961: *; Meshkova 1961: ; Tshernova 1970: ; Tshernova & Sinitshenkova 1974: '; McCafferty 1990: '; Martins-Neto 1996: '; Kluge 2004: * *

Autapomorphies of Hexagenites/fg1.

(1) On fore wing CuA bifurcates to CuA1 and CuA2 (non-unique character see Index of characters [2.2.50]), from the bifurcation a vein iCu arises, which forms several (35) triads following one another: anterior branch of each triad forms next triad; each of these triads has anterior branch arched by its convexity anteriorly; all branches of these triads go to basitornal margin of wing. Unique apomorphy.

(2) Fore and hind wings with more or less expressed vein gemination: at least there are pairs of veins brought together: RSp+MA1, iMA+MA2, MP2+CuA; MP1 and iMP are more or less approximated to iMA+MA2. Non-unique apomorphy (see Index of characters [2.2.28]).

(3) Tergalius VII is enlarged, distinctly longer than others, while tergalii I-VI have subequal length (unique apomorphy). On all tergalii at least costal rib is thickened and anal rib is situated at a distance from anal margin (as in some other mayflies see Index of characters [1.3.28]).

Plesiomorphies of Hexagenites/fg1. Larva has siphlonuroid appearance, with dense primary swimming setae on caudalii.

Size. Fore wing length 1642 mm.

Age. Late Jurassic Late Cretaceous (Europe, Asia, South America).

Nominal species in Hexagenites/fg1:  

 berkeyi Cockerell 1927 [Ephemeropsis trisetalis]    

 braueri Handlirsch 1906 [Phacelobranchus] syn.subj. trisetalis [Ephemeropsis]

branchicillus Huang & Sinitshenkova & Ren 2011 [Siberiogenites]

 britoi Martins-Neto 1996 [Palaeobaetodes]

cellulosa Hagen 1862 [Ephemera typus nominis Stenodicranum

 chaneyi Cockerell 1927 [Ephemeropsis trisetalis]    

 corradiniae Martins-Neto 1996 [Cratogenites]

 costalimai Brito 1987 [Palaeobaetodes]

 delclosi Martins-Neto 1996 [Cratogenitoides]

elongatus Lin & Kong & Shih & Zhao & Ren 2018 [Hexameropsis]

 heloisae Storari & Godunko & Salles & Saraiva & Staniczek & Rodrigues 2021 [Protoligoneuria]

 hexavenulosus Huang & Ren & Sinitshenkova & Shih 2007 [Epicharmeropsis] typus nominis Epicharmeropsis 

inopinatabranchia Azar & Ferté & El Hajj & Nal & Maksound 2019 [ Libanoephemera]   typus nominis Libanoephemera

lacustris Zhang & Kluge 2007 [Shantous]   typus nominis Shantous

 lagueatus Sinitshenkova 1986 [Mongologenites]

 limai Demoulin 1955 [Protoligoneuria]

 longicercus Staniczek 2007 [Cratohexagenites]  typus nominis Cratohexagenites

 martynovae Tshernova 1961 [Ephemeropsis]

 melanurus Cockerell 1924 [Ephemeropsis]

 middendorffii Jones [Estheria]  

 middendorfi Handlirsch 1906 [Ephemeropsis] syn.subj. trisetalis [Ephemeropsis]

 minor Staniczek 2007 [Cratohexagenites]

mortua Hagen 1862 [Ephemera] syn.subj. cellulosa [Ephemera]

multinervosa Oppenheim 1888 [Ephemera] typus nominis Paedephemera syn.subj. cellulosa [Ephemera]

oppenheimi Handlirsch 1906 [Paedephemera] syn.subj. cellulosa [Ephemera]

 orientalis Eichwald 1868 [Ephemeropsis] syn.subj. trisetalis [Ephemeropsis]

 quadrivenulosus Huang & Ren & Sinitshenkova & Shih 2007 [Epicharmeropsis]

 reisi Handlirsch 1939 [Ephemeropsis] syn.subj. trisetalis [Ephemeropsis]

 rossica Eichwald 1866 [Lethaea] syn.subj. trisetalis [Ephemeropsis]

 selini Tshernova & Sinitshenkova 1974 [Hexameropsis]

 shangyuanensis Lin & Huang 2001 [Caenoephemera]

 trisetalis Eichwald 1864 [Ephemeropsis

weyenberghii Scudder 1880 [Hexagenites] syn.subj. cellulosa [Ephemera]

See also: 

other Euplectoptera INCERTAE SEDIS