CLADOENDESIS OF EPHEMEROPTERA

A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z 

(1) Maxillary palp lost muscles (while in other mayflies it has muscles attached to its base and muscles in 1^st segment, which move 2^nd segment). In most representatives maxillary palp is diminished, but in Tricorygnatha and Machadorythus it is secondarily elongate; usually all 3 segments are retained, but when the palp is strongly diminished, its segments can be fused together.

In connection with loss of musculature, maxillary palp disappeared many times independently in various taxa of Ephemerella/fg1: It is absent in Eurylophella/fg1, but retained in other Timpanoga/fg1; absent in selected species of Cincticostella/g3, but retained in other Ephemerella/fg4; absent in selected species of Torleya/g2 and present in others; absent in Teloganopsis, Uracanthella and Amurella; among Hyrtanella/f2=Crinitella/g1 – absent in sp.HC1, but retained as non-segmented vestige in two other species; present in Vietnamella; absent in all Ephemerellina/g1 and Teloganodes/f1=g3; among Afrotricorythi – absent in Ephemerythus and Sparsorythus, but retained in other taxa; among Leptohyphes/fg1 – absent in popayanicus [Tricorythodes], but retained in other Tricorythodes/fg1, as well as in Leptohyphes/fg2 and Allenhyphes.

Among other mayflies, loss of maxillary palp took place only once, in Madecocercus, and loss of musculature – only in Acanthametropus/fg2, which has strongly specialized mouth apparatus (see Index of characters [1.1.41]). In Ephemerella/fg1 maxillae have no initial specialization, and are variably specialized in selected representatives [see (16)].

(2) Paraglossae are fused with mentum: at least suture separating paraglossae from mentum is always lost (at the same time glossae can be distinctly separated from mentum). Non-unique apomorphy, the same in Posteritorna.

(3) In labial palp 2^nd segment lacks muscle-adductor of 3^rd (terminal) segment; non-unique apomorphy; 3^rd segment is usually diminished, but nearly always retained (only in Coryphorus lost).

(4) Larval pronotum with more or less expressed V-shaped impression, which goes from anterior-lateral angles medially-posteriorly (Kluge 2004: Fig.92:C–D). Possibly, this structure is homologous to the pronotal collum of Fimbriatotergaliae [see Fimbriatotergaliae (1)].

(5) Larval fore protoptera are fused one with another by mean of a mesial plate, which has a median incision on posterior margin; the fore protoptera convergent by their apices (Kluge 2004: Fig.91:A); sometimes (particularly in Tricorygnatha) they are fused by their apices, in this case apex of the mesial plate between them is not expressed (Kluge 2004: Fig.97:E); only in Timpanoga/fg4 protoptera somewhat diverge (that is connected with strong widening of body). When adult fore wings develop inside protoptera, a pair of membranous processes can develop inside the mesial plate (Kluge 2004: Fig.101:A and 102:A–B); thus adult can have a pair of short or long membranous processes (plumidia) on posterior margin of mesonotal scutellum (Kluge 2004: Fig.89:A–B). Non-unique apomorphy (see Index of characters [1.2.6] and [2.2.13]).

(6) On fore wing CuP in its proximal part is connected with CuA by a constant crossvein cua-cup, and with AA – by a constant crossvein cup-aa. Presence of these constant crossveins is not connected with course of tracheae: veins cua-cup, cup-aa, AA, CuP and proximal portion of CuA lack tracheae, and distal portion of CuA is supplied by trachea from MP (as in majority of mayflies, unlike Campsurus/fg1); the common trachea of MP and CuA can penetrate into the wing either with other tracheae, passing in front of basal wing plate, or rounds the basal wing plate from behind (among Ephemerella/fg1, tracheation was examined in thani [Vietnamella], aculea [Ephemerella] and commodema [E.]).

All Ephemerella/fg1 except for Tricoryptera, have uniform structure of wing base (Kluge 2004: Fig.90:A): cua-cup is located more distally than cup-aa; CuP arises from CuA under acute angle (plesiomorphic condition) and is sharply bent at the place of connection with cua-cup. In Tricoryptera this structure is modified, portion of CuP proximad of connection with cup-aa is lost (Kluge 2004: Fig.89:K-M) [see below, Tricoryptera (1)].

This character differs Ephemerella/fg1 from other extant taxa; but the same feature of wing structure occurs in extinct mupengxui [Siphlonephemerella] [comp.: Siphlonephemerella/fg(1) ()].

(7) Each tergalius II–VI [bilobed and lacking marginal ribs – see Furcatergaliae (5)] initially consists of a dorsal and a ventral lobes; dorsal lobe represents initial tergalial lamella and can retain costal and anal ribs (see below, Plesiomorphies of Pantricorythi); ventral lobe bifurcates to two branches – costal branch (located most laterally, under costal margin of dorsal lobe) and anal branch (located most medially, under anal margin of dorsal lobe); each branch bears on its outer side a row of processes (Kluge 2004: Fig.89:C–G, 91:D–F, 97:F–G). Unique apomorphy. 

Tergalius VII is diminished or lost; if present, it also consists of the dorsal and ventral lobes, but its ventral lobe is never bifurcate [see (7a)]. 

Usually tergalii II–VII lie dorsally on abdomen and are directed by their apices posteriorly, overlapping tergalii located posteriad of them; lateral margins of abdominal segments are often expanded laterad of tergalii (Kluge 2004: Fig.91:A,I). In connection with this, in selected groups of Ephemerella/fg1 tergalii of the anteriormost pair are transformed to gill opercula; these can be tergalii II, III or IV (see Table and Index of characters [1.3.32]). Usually tergalii retain ability of rhythmical respiratory movements (see Index of characters [1.3.30]); tergalii transformed to gill opercula can lost this ability (see Index of characters [1.3.32]).

In various groups of Ephemerella/fg1 tergalii of this or that pairs can be simplified in structure or lost (see Table and Index of characters [1.3.19–21] and [1.3.54–59]). Only in Dicercomyzon tergalii are modified so strongly, that completely lost the structure initial for Ephemerella/fg1. About tergalius I – see (13).

(7a) In larvula tergalius VII appears earlier than other tergalii, so in some instars it is larger than other tergalii (Durken 1923: Ephemerella ignita); even when tergalius VII is lost in mature larva [see (7)], it is retained and develops first in larvula (Kluge 2010: Fig.31-34).

(8) Imaginal and subimaginal gonostylus with 1 distal segment only (instead of two initial ones). Non-unique apomorphy (see Index of characters [2.3.12]). In some Ephemerella/fg1 (Afrotricorythi and some others) the distal segment is lost.

(9) Imaginal and subimaginal mesonotal suture is transverse; in the point of its crossing with the median longitudinal suture its margins can be somewhat separated, between them a small membranous area can be expressed (Kluge 2004: Fig.90:D); such distinctly expressed mesonotal suture is present in all Ephemerella/fg2, as well as in Vietnamella, Ephemerellina/g1 and Teloganella, but in Teloganodes/f1=g3 and Tricoryptera it can be poorly expressed, up to disappearance (Kluge 2004: Fig.104). In all cases mesonotal suture is never transferred backward (unlike Fimbriatotergaliae, Leptophlebia/fg1 and Tetramerotarsata), only at crossings with medioparapsidal sutures it can be narrowly stretched backward (Kluge 2004: Fig.90:D).

(10) Lateroparapsidal suture is curved by its posterior end laterally, and subimaginal lateral sclerotized area is medially bordered by a relief line, which passes mediad of lateroparapsidal suture and is arched by its convexity medially; correspondingly, the lateral sclerotized area occupies the lateroparapsidal suture, whole sublateroscutum and most part of lateroscutum (Kluge 2004: Fig.90:D).

Such structure of the lateral sclerotized area is present in all Ephemerella/fg2. In various taxa of Pantricorythi structure of mesonotum is quite various: lateroparapsidal suture can be either curved laterally (Kluge 2004: Fig.99:D) or convergent with medioparapsidal suture (Kluge 2004: Fig.98:D); the relief line can be ether present or absent; lateral sclerotized area can have different shape (Kluge 2004: Fig.96:A) or be absent (Kluge 2004: Fig.104:I) (see Index of characters [2.2.9] and [2.2.14]). However, among Pantricorythi the same structure of mesonotum as in Ephemerella/fg2, is present in Vietnamella and some others; this allows to conclude that such structure is initial for Ephemerella/fg1.

Apomorphies of Ephemerella/fg1 common with Potamanthus/fg1 and Caenotergaliae (see Classifications of Furcatergaliae I).

(11) Larval mesonotum has a collar – a concave band at anterior margin, separated from the rest part of mesonotun by a transverse crest (Kluge 2004: Fig.92:C–D). The same in Potamanthus/fg1, Euthyplocia/fg1 and Caenotergaliae.

(12) Dorsal (anterior) surface of larval fore femur can bear a transverse row of setae (Kluge 2004: Fig.89:H–J); sometimes this row is irregular, indistinct or lost. The same in Caenotergaliae and Potamanthus/fg1. About peculiar shape of this row in Pantricorythi – see below.

(13) Tergalius I is stick-like, setose, attached on a prominent cylindrical pedestal which can arise either from anterior part of the abdominal segment I (Kluge 2004: Fig.95:D–E) (the same in Potamanthus/fg1 and Caenotergaliae), or from posterior part of the segment (Kluge 2004: Fig.91:G–H); apical part of pedestal can be membranous and retractile.

In many Ephemerella/fg1 tergalii I are completely lost, being retained only in Timpanoga/fg1, Vietnamella, Teloganella and selected Melanemerella/fg1 (see Index of characters [1.3.33]) (unlike Potamanthus/fg1 and Caenotergaliae, where they are retained in all representatives).

(14) Egg with a polar cap and peculiar anchors (MFT). Usually there is a large cap on one pole; only in selected cases the polar cap is absent (in Eurylophella/fg2 and selected species of Tricoryptera) or caps are present on both poles (in simplex [Ephemerella] and Tricorythopsis). Sometimes several anchors are present; each anchor consists of a terminal knob and a skein of threads, which surround the knob in a form of regular ring (Studemann & Landolt 1997a: Fig.1–54); such kind of anchors is called MFT (multi-folded with terminal fiber cluster), in contrast to superficially similar KCT [see Branchitergaliae (4)] (Uber-Pascal & Puig 2009). Similar polar caps and anchors are present in Potamanthus/fg1, and caps – also in some Caenotergaliae.

(15) In cubital field of fore wing [see Anteritorna (1)] the most constant element is a bifurcate vein initially arising from CuA – 1^st cubital fork (Kluge 2004: Fig.90:A, 95:A, 99:A and 100:A: x₁, x₂). More distally from CuA can arise two other bifurcate veins – 2^nd and 3^rd cubital forks. All 3 cubital forks occur in Vietnamella only (Kluge 2004: Fig.95:A: x, y, z). Ephemerella/fg2, Austremerella and Teloganodes/f1=g3 have only the 1^st and 2^nd cubital forks or their vestiges; both forks in form of integral bifurcate veins arising from CuA occur in a few largest representatives of Ephemerella/fg2 (Allen & Edmunds 1962a: Fig.11); in most species one or both branches of the 2^nd cubital fork lost connection with CuA and become intercalaries (Kluge 2004: Fig.90:A: y₂); sometimes the same happens with the 1^st cubital fork also. Tricoryptera have only the 1^st cubital fork, which sometimes lost connection with CuA (Kluge 2004: Fig.99:A and 100:A: x₁, x₂).

The same cubital forks, besides Potamanthus/fg1 and Caenotergaliae, occur in some other mayflies (see Index of characters [2.2.51]).

Non-unique apomorphies of Ephemerella/fg1.

(16) Apical-ventral side of maxilla [see (1)] bears a field of long setae, usually situated densely and regularly; this field is close to base of maxillary canines, being located on a protuberance, from which canines arise. In representatives with biting maxillae this setal field can be strongly diminished (Kluge 2004: Fig.95:C; Ikonomov 1961: Fig.3:13), in representatives with filtering maxillae (Cincticostella/g2, Uracanthella and others) this field is enlarged and maxilla has a truncate shape (Kluge 2004: Fig.92:H, 93:B); scraping maxillae of Dicercomyzon have this field extremely enlarged (see Index of characters [1.1.29]). The same field of setae is present in Potamanthus/fg1 and Euthyplocia/fg1, a similar field – in Leptophlebia/fg1. Apical-ventral row of setae is absent (unlike many Leptophlebia/fg1, Radulapalpata and Tridentiseta – see Index of characters [1.1.31]).

(17) Imaginal and subimaginal furcasternal protuberances of mesothorax are separated. Non-unique apomorphy (see Index of characters [2.2.23]).

(18) Larval claw usually with one row of denticles on inner side (non-unique apomorphy – see Index of characters [1.2.21]); sometimes denticles are lost [see Timpanoga/fg3 (1) below]; sometimes, apart of this row, there are also subapical denticles on anterior and/or posterior side. In an exceptional case two regular rows of denticles are present (in crassi [Ephemerellina] and brincki [E.]).

Unlike mature larva, larvula has 2 equal rows of denticles on inner side of claw (Degrange 1960; Kluge 2010: Fig.31-34). 

Non-unique character: the same in some Leptophlebia/fg1, Pentamerotarsata and others taxa (see Index of characters [1.2.21-22]).

(19) Larval abdominal terga often have paired submedian projections at posterior margin (Kluge 2004: Fig.91:A); such projections are present in many Ephemerella/fg2 and most primitive Pantricorythi – Vietnamella, Austremerella and some Melanemerella/fg1, that allows to conclude that this structure is initial for Ephemerella/fg1. In many species paired abdominal projections are poorly expressed or absent. Only in a few taxa of Ephemerella/fg1 abdominal terga have unpaired median projections instead of paired ones – these are Ephemerella/fg3-Amurella and some Pantricorythi (see Index of characters [1.3.3]).

Plesiomorphies of Ephemerella/fg1. Imaginal and subimaginal claws are ephemeropteroid (only on fore legs of male can be blunt — see Index of characters [2.2.77]). Larval, subimaginal and imaginal paracercus is nearly always well-developed, being subequal to cerci; only in Teloganodes/f1=g3 and Dicercomyzon paracercus is reduced both in larva and adults.

Variable characters of Ephemerella/fg1. Larval and adult patella-tibial suture is usually developed on middle and hind legs (as in majority of mayflies), but in selected taxa this suture is lost on all legs: it is retained in all species examined of Timpanoga/fg1, plesiomorphon Torleya/g2 and plesiomorphon Ephemerella/fg5; among Drunella/g1 – lost in lepnevae [Ephemerella], doddsi [E.], coloradensis [E.] and spinifera [E.], but retained in other species examined; among Cincticostella/g1 – lost in larva of tshernovae [Ephemerella], but retained in its adults and in other species examined; lost in larvae of both Caudatella/g(1) species examined; among the taxa examined of Pantricorythi, this suture is lost in larvae and adults of Teloganodes/f1=g3, Tricorygnatha and Dicercomyzon, but retained in Vietnamella, Teloganella, Ephemerythus, Machadorythus and Leptohyphes/fg1 (Kluge 2004: Fig.105:A).

Taxon

WWWWWWWWWWWWWWWWWW

Pairs of tergalii

I

II

III

IV

V

VI

VII

Ephemerella/fg1 (7), (13)

- Ephemerella/fg2 (1)

- - Timpanoga/fg1 (1), (P)

- - - Attenella (P)

±

–

–

–

–

- - - Timpanoga/fg2 (1)

+

–

–

–

–

- - Ephemerella/fg3 (1)

- - - Ephemerella/fg4 (1)

–

–

–

- - - Torleya/fg1 (P) 

–

–

–

- - - –"– 

–

–

–

- Pantricorythi (P)

- - Vietnamella (P) 

+

- - Austremerella (P) 

–

- - Melanemerella/f1=Teloganodes/g1 

–

–

–

–

- - - harrisoni [Lithogloea]

+

–

–

–

- - - barnardi [Ephemerellina]

–

–

–

–

- - - brincki [Ephemerellina]

–

–

–

–

–

- - - crassi [Ephemerellina]

+

–

–

–

–

- - - penicillata [Lithogloea]

+

–

–

–

–

–

–

–

- - Melanemerella/f2=Teloganodes/g2

- - - Teloganella (3)

–

–

–

–

–

–

- - - Melanemerella/f3=g1

–

–

–

–

- - - Teloganodes/f1=g3 (1), (8)

- - - - insignis [Macafertiella]

–

–

–

–

- - - - tuberculatus [Teloganodes]

–

–

–

–

- - - - kodai [Teloganodes]

–

–

–

–

- - - - sp. T4 

–

–

–

–

–

–

- - - - spp. [Dudgeodes] 

–

–

–

–

–

–

- - - - jacobusi [Teloganodes] 

–

–

–

–

–

–

- - - - hubbardi [Teloganodes] 

–

–

–

–

–

–

- - - - eloisae [Derlethina]

–

–

–

–

–

–

–

–

- - Tricoryptera (5), (6)

- - - Afrotricorythi

- - - - Tricorygnatha (P):

- - - - - jacobsoni [Tricorythus]
- - - - - bifurcatus [Sparsorythus]

–

–

- - - - - other species 

–

–

–

- - - - Ephemerythus (1)

–

–

–

–

- - - - –"–

–

–

–

–

–

–

- - - - Dicercomyzon (4)

–

–

–

- - - - Machadorythus (5)

–

–

–

–

–

–

- - - Leptohyphes/fg1 (1)

- - - - Leptohyphes/fg2 (P)

–

–

–

- - - - Allenhyphes (3)

–

–

–

- - - - Tricorythodes (6)

–

–

–

- - - - –"–

–

–

–

- - - - –"– 

–

–

–

–

- - - - Tricorythopsis (8)

–

–

–

–

- Coryphorus/g1 (3)

- - aquilis [Coryphorus]

–

–

–

–

–

- - sp. Cor1

–

–

–

–

–

–