Ecdyonurus Eaton 1868

Kluge, Nikita, Sivaruban, T., Srinivasan, Pandiarajan, Barathy, S. & Isack, Rajasekaran, 2023, Redescription of the subgenus Rhithrogeniella Ulmer 1939 (Ephemeroptera, Heptageniidae, genus Ecdyonurus) based on reared specimens from India and Thailand, Zootaxa 5319 (4), pp. 501-523 : 503

Genus Ecdyonurus Eaton 1868 s. l.

, or Ecdyonurus /fg1

( Figs 1–116 )

Type species: Ephemera venosa Fabricius 1775 (with neotype designated by ICZN 2015 : Opinion 2356) .

Diagnosis (according to Kluge 2004)

Metathoracic nerve ganglion greatly transferred anteriorly, nearer to mesothoracic ganglion, being connected with it by short unpaired connective; due to this, imaginal and subimaginal median impression of furcasternum parallel-sided or widened toward its anterior part (not narrowed in anterior part, in contrast to all other Heptageniidae ) ( Fig. 107 ).

Left and right mandibles have incisors dissimilar: incisor of left mandible (with mola projected distally) pointed, with a row of denticles on inner margin; incisor of right mandible (with mola projected proximally) with large denticle at some distance from apex and row of smaller denticles proximad of it; denticles on outer margins of both incisors at a distance from apex ( Figs 29–30 ).

Superlinguae of peculiar shape uniform for all representatives, with rounded apico-lateral projection ( Fig. 32 ).

On maxilla, ventral row of setae transformed to field of irregularly situated setae (unique apomorphy) ( Figs 28, 33 ). Proximal dentiseta always bifurcate ( Fig. 33 ).

Vestige of segment 3 of maxillary palp triangular, larger than in Heptagenia /f6=g5 ( Fig. 28 ).

Glossae rhomboid, with inner margin convex ( Fig. 31 ).

Tergalii are differentiated as following: tergalius I narrowed, with concave anal margin (i.e. more or less banana-like); tergalii II–VII widened, with anal margin most convex (i.e. more or less roundish-triangular). Unique apomorphy.

Outer (posterior) margin of larval femur with regular row of long stout setae situated less dorsally, than similar setae in Rhithrogena /fg1 and Cinygma . ( Figs 34–35 ).

Composition. The genus Ecdyonurus s. l. is divided into several subordinated taxa which can be treated as subgenera ( Kluge 2004), with the subgenus Rhithrogeniella among them.

Figures

FIGURES 1–10. Ecdyonurus (Rhithrogeniella) ornatus from Kodaikanal (India). 1–3, larvae; 4–10, tergalii I–VII.

FIGURES 11–25. Ecdyonurus (Rhithrogeniella) ornatus, larval exuviae. 11–14, specimen from Agumbe (India); 15–18, 19–21 and 22–25, specimens from Pai (Thailand) (11, 15, 19, 22, head; 12, 16, 20, 23, half of pronotum and mesonotum; 13, 17, 24, hind leg; 14, 18, 21, 25, abdomen).

FIGURES 26–33. Ecdyonurus (Rhithrogeniella) ornatus, larval mouthparts. 26, labrum; 27, anterior margin of labrum bent ventrally; 28, maxilla; 29–30, apices of left and right mandibles; 31, glossa and paraglossa of labium; 32, hypopharynx and superlingua; 33, apex of maxilla, dorsal view. Abbreviations: c1, c2, c3, three maxillary canines; ds1, distal (first) dentiseta; ds2, proximal (second) dentiseta; i-d, inner-dorsal row of setae; i-v, first (largest) seta of inner-ventral setal row; in, incisor; kd, kinetodontium; prs, prostheca.

FIGURES 34–41. Ecdyonurus (Rhithrogeniella) ornatus, exuviae of larval legs (reared specimen from Kodaikanal). 34, fore femur; 35, outer margin of fore femur; 36–38, fore, middle and hind legs; 39, hind tibia; 40, hind tarsus; 41, claw.

FIGURES 42–52. Larvae. 42–50, Ecdyonurus (Rhithrogeniella) ornatus, larval exuviae: 42–44, specimen from Agumbe (India), posterior margins of abdominal terga I, VIII and X; 45, specimen from Pai (Thailand), posterior margins of abdominal tergum VI; 46–48, cercus of specimen from Agumbe: 46, proximal portion; 47, middle portion in median-ventral view, to show bases of primary swimming setae on inner (median) side; 48, the same portion with focus on lateral-dorsal side, to show bases of secondary swimming setae on outer (lateral) side; 49–50, cercus of specimen from Kodaikanal (India). 51–52, Ecdyonurus (Rhithrogeniella) joernensis (Russia, Orenburg province, Tashla, 16.VIII.1986, coll. N. Kluge): two portions of cercus, dorsal view.

FIGURES 53–68. Ecdyonurus (Rhithrogeniella) ornatus. 53–56, male abdomina to show hypodermal coloration: 53, subimago extracted from mature larva; 54–55, imagines; 56, subimago; 57, male imago; 58–60, fore and hind wings; 61, hind wing; 62– 63, fore and middle legs of male imago; 64, male imago with subimaginal exuviae; 65, 1st tarsal segment of male subimaginal exuviae; 66–67, exuviae of half of subimaginal mesonotum; 68, cercus of male imago (53, 54, 57–60, 66, from Pai; 56, 61, 67, from Kwai-Yai; 56, 61, 67, from Agumbe; 64–65, from Kodaikanal). Abbreviations: cz.a, anterior chromozone; cz.lp, lateroparapsidal chromozone; cz.ps, chromozone of parascutellum.

FIGURES 69–72. Ecdyonurus (Rhithrogeniella) ornatus, genitalia of male imagines, ventral view. 69–70, specimen from Kodaikanal (India) in tense condition; 71, specimen from Agumbe (India); 72, specimen from Pai (Thailand).

FIGURES 73–76. Ecdyonurus (Rhithrogeniella) ornatus, development of penis. 73–74, imaginal penis and its subimaginal exuviae with minute points of titillators; 75, subimaginal penis extracted from mature larva, with imaginal titillators developing under subimaginal cuticle; 76, subimaginal penis extracted from mature larva, without tissues under subimaginal titillators (73–74, 76, from Pai; 75, from Kodaikanal. Abbreviations: tit.i, imaginal titillator; tit.s, subimaginal titillator).

FIGURES 77–84. Ecdyonurus (Rhithrogeniella) ornatus, female imagines. 77–78, specimen from Agumbe (India); 79–81, specimens from Kwai-Yai (Thailand); 82–84, specimens from Pai (Thailand).

FIGURES 85–90. Ecdyonurus (Rhithrogeniella) ornatus, fully developed eggs from India. 85–86, reared imago from Agumbe, specimen [XIII](2)2013; 87–88, reared imago from Agumbe, specimen [IX](6)2013; 89–90, mature larva from Kodaikanal.

FIGURES 91–96. Ecdyonurus (Rhithrogeniella) ornatus, fully developed eggs from Pai (Thailand). 91–92, reared imago, specimen [XIII](4)2015; 93–94, reared imago, specimen [XIX](1)2015; 95–96, reared subimago, specimen [XVIII](4)2015.

FIGURES 97–102. Ecdyonurus (Rhithrogeniella) ornatus, fully developed eggs of reared imagines from Kwai-Yai (Thailand). 97–98, specimen [III](11)2015; 99–100, specimen [III](37)A2015; 101–102, specimen [IV](2)2015.

FIGURES 103–110. 103–109, Ecdyonurus (Rhithrogeniella) sp. 2: 103, male imago, 104, abdomen of male imago; 105, male subimago; 106, female subimago; 107, thorax of male subimago, ventral view; 108, male subimaginal exuviae; 109, enlarged part of its ventral arc of prealar bridge; 110, the same of E. (Rh.) ornatus.

FIGURES 111–116. Ecdyonurus (Rhithrogeniella) sp. 2: 111, genitalia of male imago; 112, penis of male subimago; 113–114, penes of male imagines; 115–116, eggs.