(1) Labium is strongly modified as scraping (Kluge 2004: Fig.57:F-H):

Submentum is not expressed [see Pentamerotarsata (1)]; mentum is large, transverse; most part of it is occupied by strongly thickened muscles-adductors of labial palps; these muscles are directed transversely and their immobile ends are connected together at median plane without any skeleton formations. Probably such musculature can be used for synchronous work only. Abductors of labial palps are lost.

1^st segment of labial palp is very strongly thickened, with strongly convex outer margin, projecting proximally from its place of attachment; most part of the 1^st segment is occupied by a strongly thickened fan-form flexor of 2^nd segment, proximally the flexor is attached to the most part of the convex outer margin of the segment (somewhat similar place of attachment of this muscle in Ametropus – see Index of characters [1.1.56]).

Distal (2^nd+3^rd) segment of labial palp [see Heptagennota (8)] is massive and has following unique structure: On outer-ventral side it bears a field of densely and regularly situated small curved scraping setae. On ventral side it has a longitudinal arched sclerotized pigmented crest. On dorsal side it bears a field of irregularly situated setae; distally this field is bordered by a regular transverse row of setae. Only in one species [see Raptoheptagenia (1) below] 2^nd+3^rd segment of labial palp secondarily lost its scraping specialization and is transformed to a sclerotized claw; but on ventral side of this claw near its apex, one row of vestiges of the scraping setae is retained (Kluge 2004: Fig.60:B).

Paraglossae are widened, much wider than glossae, with divergent lateral margins; each paraglossa is roundish or with blunt apical-median angle and with wide straight or roundish apical margin (unlike Arthroplea, Pseudiron and majority of other mayflies, where paraglossa is crescent-shapely arched and has an acute apical-median angle). In various Radulapalpata width of paraglossa can be subequal or much larger than its length; length of paraglossa can be subequal or much less than length of glossa.

Glossae have variable shape; probably the initial for Radulapalpata is a pyramidal shape, when the glossa has maximum width near its base, narrows toward its apex and has three longitudinal ridges convergent toward apex – lateral, median and dorsal ones. Such shape of glossae occurs in non-related taxa – Dacnogenia, Rhithrogena/fg2, Epeorus/fg2 and Paegniodes; in other Radulapalpata glossae shape is modified: glossa can be flattened because its dorsal ridge is approximated to median ridge, can be widened apically (see Index of characters [1.1.50]).

(2) In larva posterolateral spines on abdominal segment IX are nearly always lost, and if present are much smaller than spines on previous segments: in species which have posterolateral spines on several segments, spines of segment VIII are the largest; in some species posterolateral spines are absent on all segments. The same in Chiloporter only. In many other mayflies posterolateral spines increase from anterior segments toward segment IX, and spines of segment IX are the largest.

(3) On maxilla pectinate setae of the apical-ventral row are directed medially (i.e. toward canines) arising under acute angle, and usually have a peculiar shape: basally stout, distally widened and flattened, brush-like, with widening directed dorsally-proximally, and all processes directed medially (Kluge 2004: Fig.58:F,H). Probably presence of a regular apical-ventral row of pectinate setae belongs to archetype of Ephemeroptera, as pectinate setae are present in such non-related groups, as Siphlonurus/fg1 (especially well-developed in Siphlonurus/fg4 palaearcticus [Oniscigaster]), Ameletus/fg1, Leptophlebia/fg1 and others. In Radulapalpata these setae have unique shape. In some representatives of Radulapalpata (Raptoheptagenia, Cinygma, Epeorus/fg3 and others) these setae are partly or completely reduced. It is unclear, if absence of these setae in Arthroplea and other Branchitergaliae is primary or secondary, so it is unclear if their peculiar structure is an autapomorphy of Radulapalpata or of a higher taxon.

Probably the initial shape of maxilla in Radulapalpata is elongate and close to rectangle – i.e. with developed apical margin, nearly straight apical-median angle and with long straight median margin, which length approximately 1.5 times exceeds total width of maxilla; such maxilla shape occurs in many Heptagenia/f6=g5, in Cinygma, Bleptus, Ironodes and Paegniodes. In some taxa of Radulapalpata maxilla is shorter and has more acute apical-median margin [particularly, see Rhithrogena/fg2 (1) and Epeorus/fg3 (1) below].

Plesiomorphies of Radulapalpata. Unlike Arthroplea, on fore wing RSa₂ always retains its connection with RSa. Gonostylus usually with 2 distal segments, but in tetramera [Cinygmula] with 3 distal segments.

Variable characters of Radulapalpata. Mandibles are usually normal: mandible with distally projected mola is left one, and mandible with proximally projected mola is right one (Kluge 2004: Fig.54:E-F); only in selected species and infra-species taxa mandibles are inverted – in the single species of Dacnogenia, in Heptagenia/f8=g7 sulphurea dalecarlica [H.], sulphurea albicauda [H.], Leucrocuta/g1 inversus [Ecdyonurus] (the same in Arthroplea).