CLADOENDESIS OF EPHEMEROPTERA

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(1) Larva [burrowing – see Fossoriae (1)] has on its head, thorax and abdomen projections of unique shape which are covered by stout setae directed posteriorly, that helps to move in sand (Kluge 2004: Fig.73:A,E):

Larval frons anteriorly bears a pair of wide rounded projections which cover from above not only clypeus [see Fossoriae (2)], but also antennae bases; these projections are densely covered with stout setae directed posteriorly. Due to this, imaginal antennae are located on a pair of projections directed anteriorly (Tshernova 1938: Fig.1).

On larval pronotum ends of the crest separating collar [see Fimbriatotergaliae (1)] are transformed to a pair of large flat antero-lateral projections, densely covered with stout setae directed posteriorly.

Larval mesothoracic episterna are more or less projected anteriorly in a form of bald sclerotized projections (especially remarkable in Behningia/ /fg2), and epimera are densely covered with stout setae directed posteriorly.

Larval abdominal terga bear a pair of longitudinal ridges covered with setae; in Protobehningia these ridges are shallow (Kluge 2004: Fig.73:E), while in Behningia/fg2 they are projected laterally and cover tergalii from above (Kluge 2004: Fig.73:A-B).

In Protobehningia burrowing leg specialization is retained, but in Behningia/fg2 body shape and method of movement in sand are strongly modified, and leg specialization is changed (see below).

(2) Mouth apparatus [located at a distance from anterior margin of head because of frontal projections – see (1)] is specialized for carnivorism:

Mandible is shortened perpendicular to its axis of articulation, mola without grater, incisor and kinetodontium are stout; initial asymmetry of mandibles is either lost (in Behningia/fg3), or nearly lost (in Protobehningia and Dolania) (Elpers & Tomka 1994b:Fig.4,5,19,20).

Labium has glossae and paraglossae more or less diminished and palps enlarged, massive, without muscle inside 2^nd segment (border between 2^nd and 3^rd segments is distinct in Dolania, and indistinct in Protobehningia and Behningia/fg3).

(3) Winged stages are short-living; moult from subimago to imago takes place in males only; middle and hind legs of male and all legs of female are non-functional (non-unique apomorphy – see Index of characters [2]). In female all legs are vestigial, tarsi are non-segmented, claws are lost. In male imago middle and hind legs lack tarsi; at least in Dolania (according to Peters & Peters 1986) middle and hind legs of male subimago with 2-segmented tarsus and one claw.

(4) RSa₂ of fore wing is simple, not forming triad. The same in some other short-living mayflies [see (3)] (see Index of characters [2.2.37]).

(5) On fore wing bifurcation of MA is transferred to wing base. The same in some other short-living mayflies [see (3)] (see Index of characters [2.2.43]).

(6) Cubital field of fore wing [see Anteritorna (1)] with 1–8 intercalaries sometimes alternating as concave and convex, the anteriormost intercalary being the longest (non-unique apomorphy — see Index of characters [2.2.52]). CuA is either simple (in Protobehningia), or bifurcate [see Behningia/fg2 (3) below], thus no more than one vein arises from CuA.

(7) Amphitornal margin of imaginal wing bears setae similar to that of subimago. Non-unique apomorphy (see Index of characters [2.2.27]).

(8) In male imago on fore legs (elongate and specialized for grasping female, as in other mayflies) tarsus is non-segmented, with one blunt claw only (Keffermuller 1959: Pl.V; Peters & Peters 1986: Fig.1; Peters & Gillies 1991: Fig.2). Unique apomorphy.

(9) Penis lobes are very long, much longer than gonostyli [at the same time gonostyli are normally developed, not shortened – see (10)]. Unique apomorphy: besides Behningia/fg1 so long penes are present only in some Geminovenata, but there penes are protractible, while penes of Behningia/fg1 are rigid.

(10) Gonostylus [see (9)] lacks distal segments. Non-unique apomorphy (see Index of characters [2.3.12]).

(11) Imaginal and subimaginal caudalii [see (12)] lack distinct segmentation. Non-unique apomorphy, the same in some Palingenia/f3=g2 and others.

(12) In male imago paracercus [see (11)] is shortened, much shorter than cerci: 1/2 of cerci length in Protobehningia and strongly shortened in Behningia/fg2 (but in female paracercus is subequal to cerci). Non-unique apomorphy (see Index of characters [2.3.22]).

Characters of Behningia/fg1 of doubtful polarity (see Classifications of Fimbriatotergaliae II).

(13) Mandibles lack tusks. Probably result of reduction [see Fimbriatotergaliae (8)].

(14) On inner side of femur and tibia of larval hind leg spiny setae are absent. Probably result of reduction [see Fimbriatotergaliae (9)].

(15) Tergalius I [different from others – see Fimbriatotergaliae (6)] has a form of a single large (as long as tergalii of next pairs) lamella with numerous marginal processes (Kluge 2004: Fig.73:A,E). As in other Fimbriatotergaliae tergalius I is strongly diminished and always lacks processes, we can assume that in Behningia/fg1 vestige of this tergalius has been secondarily enlarged and got the same processes as on tergalii II-VII, but remains to be unilamellate.

Plesiomorphies of Behningia/fg1. Maxillary palp is always 3-segmented [in spite of specialization of mouth apparatus – see (2)] (unlike Cryptoprosternata). Furcasternal protuberances are contiguous (unlike Campsurus/fg1, Caenotergaliae and some others – see Index of characters [2.2.23]).