CLADOENDESIS OF EPHEMEROPTERA

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(1) Larval clypeus projectes forwards as a shelf above base of labrum (Kluge 2004: Fig.69:F,I). Unique apomorphy. By its form this clupeal shelf resembles frontal projection of Fossoriae, but is not homologous to it: clypeal shelf of Euthyplocia/fg1 is located ventrad of anterior tentorial pits, while frontal projection of Fossoriae is located dorsad of them (Kluge 2004: Fig.76:A).

(2) Mandibular tusks [see Fimbriatotergaliae (8)] are covered by dense irregular long slender setae; on inner side of tusk these setae are directed nearly perpendicular to the tusk and probably are used for filtering. Unique apomorphy: in Potamanthus/fg1 and Fossoriae setae on tusks are not so dense and long. Tusks are curved by their apices medially and besides the slender setae, bear stout spine-like setae (that is probably a plesiomorphy in limits of Fimbriatotergaliae).

(3) Larval fore tibia on inner-apical corner bears a pointed projection (Kluge 2004: Fig.69:D–E). Non-unique apomorphy (see Index of characters [1.2.35]).

(4) On fore wing bifurcation of MA [initially situated in middle of MA – see Euephemeroptera (2)] is transferred proximally. Non-unique apomorphy; among Fimbriatotergaliae the same in Behningia/fg1, Anagenesia/g1 and Polymitarcys/f1=Ephoron/g2.

(5) Gonostylus has no more than 1 distal segment (instead of two initial ones) (non-unique apomorphy – see Index of characters [2.3.12]); proximal part of gonostylus is integral, boundary between 1^st and 2^nd segments is not expressed at all (the same in Potamanthus/fg1 and some other mayflies); thus gonostylus has no more than 2 segments.

Characters of Euthyplocia/fg1 common with Potamanthus/fg1.

(6) Maxilla [see Fimbriatotergaliae (10)] on apical-ventral side close to base of maxillary canines has a field of densely and regularly situated long setae. The same in Potamanthus/fg1 and Ephemerella/fg1, a similar field – in Leptophlebia/fg1 (see Index of characters [1.1.32]).

(7) Larva has collar not only on pronotum [see Fimbriatotergaliae (1)], but on mesonotum as well (Kluge 2004: Fig.69:G). The same in Potamanthus/fg1 and Caenotergaliae, and the same mesonotal collar in Ephemerella/fg1.

Characters of Euthyplocia/fg1 common with Fossoriae.

(8) On imaginal and subimaginal mesothorax epimeron and lateropostnotum [with crest on anterior margin – see Fimbriatotergaliae (4)] are fused by their ends, forming an integral framework (Kluge 2004: Fig.69:C). The same in Fossoriae (Kluge 2004: Fig.71:C–D), while in Potamanthus/fg1 and Neoephemera/fg1 ends of epimeron and lateropostnotum are separated by membranous concavity (Kluge 2004: Fig.68:E, 83:C).

(9) Tergalius I [see Fimbriatotergaliae (6)] is vestigial, bilamellate, without processes. The same in majority of Fossoriae except for Behningia/fg1 (see Index of characters [1.3.33]); probably, symplesiomorphy of Euthyplocia/fg1 and Fossoriae.

(10) In male imago (but not in subimago) on fore leg both claws are similar and blunt. Non-unique apomorphy (see Index of characters [2.2.77]). Imaginal and subimaginal claws of middle and hind legs can be either ephemeropteroid, or pointed (Table 6); subimaginal claws of male fore leg (examined in Polyplocia only) are similar to that of other legs.

(11) In some species, whose females are much larger than males, fore wing of female (but not male) has vein gemination: apices of certain longitudinal veins are brought together forming following pairs: RSa₂''+iRS; RSp+MA₁; iRS+MA₂; sometimes also MP₁+iMP; each space between these pairs contains one or several additional intercalaries, thus spaces between all longitudinal veins have subequal width. Such gemination is present in the females examined of Campylocia, Polyplocia and Proboscidoplocia. In males of the same species and in both sexes of other species (belonging to Euthyplocia/fg2 and Exeuthyplocia/fg2) veins are not brought in pairs, and additional intercalaries are absent.

Possibly this character varies among species or individually, as gemination is also absent in some females of Proboscidoplocia (Sartori & al. 1999: Fig.1). The same gemination occurs in some other mayfly taxa (see Index of characters [2.2.28]).

Plesiomorphies of Euthyplocia/fg1. In larva: Maxilla has 3 canines and 2 dentisetae [see Bidentiseta (1)] (distal dentiseta can be slender, pressed to canines and poorly visible). Maxillary palp is 3-segmented; labial palp is 3-segmented (unlike Cryptoprosternata in Fossoriae). Larva retains long abdomen able to make undulate swimming movements; caudalii with secondary swimming setae equally developed on lateral and median sides of cerci and lateral sides of paracercus [see Furcatergaliae (6)]. All tergalii I–VII [modified – see Fimbriatotergaliae (6)] are present; tergalii II–VII are spread by sides of abdomen, not bent dorsally (the same in Potamanthus/fg1, unlike Fossoriae and Caenotergaliae).

In imago: Furcasternal protuberances are contiguous (Kluge 2004: Fig.69:H) (unlike Campsurus/fg1, Caenotergaliae and some others – see Index of characters [2.2.23]). In cubital field of fore wing sigmoid veins going toward basitornal margin [see Anteritorna (1)] are always developed; in various representatives they arise either directly from CuA, or from a secondary intercalary (see Table and characteristics below). Hind wing is usually well-developed (as long as 0.3–0.5 of fore wing lenght), rarely diminished (Kluge 2004: Fig.69:B).

Variable characters of Euthyplocia/fg1. Patella-tibial suture (initially present on middle and hind legs) can be developed on middle leg only (in larvae of Polyplocia/g1 spp. examined), or slightly traced on middle leg only (in larva of Exeuthyplocia/g1 sp.), or lost an all legs (in larva and imago of inaccessibile [Euthyplocia]).

In imago 1^st segment of middle and hind leg can be fused with tibia and shortened [see Furcatergaliae (2)] (in Polyplocia), or is secondarily separated from tibia. In Campylocia it is said to be separated on middle leg, remaining to be fused on hind leg (Berner & Thew 1961: Fig.8c-f); in Proboscidoplocia it is separated on middle and hind legs (Demoulin 1966e: Fig.1e-d; Fontaine 1968: Fig.3–5); both in Campylocia and Proboscidoplocia it remains to be shortened. In Euthyplocia/fg2 (at least in inaccessibile [E.] and intermedia [Mesoplocia]) 1^st segment of middle and hind legs is separated from tibia and elongated, being a little longer than 2^nd segment (Demoulin 1952e: Fig.1c-d); non-unique apomorphy (see Index of characters [2.2.84]). First tarsal segment of male fore leg is always short, as in other Furcatergaliae.

Egg structure, being known for a few representatives only, is quite variable. In all species of Proboscidoplocia egg has a form of mammalian erythrocyte and lacks any anchors or polar caps (Sartori & al. 1999: Fig.8–11). In Campylocia/fg1 anceps [E.] egg has two polar anchors, each consisting of lamellate round cap and a bunch of very long numerous threads, which connect the cap with egg pole; threads are coiled as a regular spiral under the cap, and when stretched exceed egg length many times. Exeuthyplocia/fg2 minima [E.] has on one pole a similar lamellate round cup attached to the egg by a short integral stem, without threads.

Taxon

Geographical distribution

Species number

Characters

Imaginal

Larval

1

2

3

4

5

Euthyplocia/fg2

Neotropical Region

4

–

1

) )

±

+

Campylocia

Neotropical Region

2

1–3

–

) )

+

–

Polyplocia

Oriental Region

2

2

–

) )

+

+

Proboscidoplocia

Madagascar

10

–

1

0 )

+

–

Exeuthyplocia/fg1

Afrotropical Region

2

–

–

0 )

–

–