CLADOENDESIS OF EPHEMEROPTERA
Heptagennota Pentamerotarsata - Arthroplea)
Nomen hierarchicum: Arthroplea/fg(1) [f:1937; g:1908]
In circumscription fits:
gen. Arthroplea Bengtsson 1908: 239
gen. Remipalpus Bengtsson 1908: 242
subfam. Arthropleinae: Edmunds & Allen & Peters 1963:13
fam. Arthropleidae Balthasar 1937: 204
Arthroplea/fg1: Kluge 2000: 251
Synonyms: subjective synonyms of Arthroplea/fg (typus A. congener) with conspecific type-species:
Remipalpus/g [g:1908] (typus R. elegans)
Haplogenia/g [g:1929] (typus H. southi)
(subjective synonymy: congener [A.] = elegans [R.] = southi [H.])
References. Bengtsson 1909: ; 1930: ; Needham & Traver & Hsu 1935: ; Balthasar 1937: ; Burks 1953: ; Edmunds & Allen & Peters 1963: ; Froechlich 1964: ; Koss 1968: ; Landa 1969a: ; Edmunds & Jensen & Berner 1976: ; Soldan 1979a: ; Studemann & Landolt & Tomka 1987: ; Kluge 2004: * * * *.
Autapomorphies of Arthroplea.
(1) Mouth apparatus has unique structure, being adopted to catch and filtrate food particles dispersed in water (Kluge 2004: Fig.53:E): Maxillary palp is unusually elongate, 2-segmented. Its 1st segment is elongate so greatly, that being turned posteriorly, reaches mesonotum; trachea, which goes to muscles of this segment (i.e. to flexor and extensor of 2nd segment), is thicker than tracheae in other appendages. Distal (2nd+3rd) segment of maxillary palp is unusually long, about twice as long as the 1st segment, slender, arched, bears two regular longitudinal rows of long filtering setae. Working by its maxillary palps, larva can gather particles dispersed in water, and also can swim back to front. Maxilla has a single canine (instead of 3 initial ones), lacks apical-ventral row of pectinate setae, bears long simple setae on apical side. Glossae are crescent-shaped, paraglossae are much larger, crescent-shaped. Distal (2nd+3rd) segment of labial palp [see Heptagennota (8)] is large, crescent-shaped, pointed, with numerous long filtering setae, among which are present: a regular longitudinal row of setae on ventral-outer side, a regular longitudinal row of setae on inner side, a field of setae on dorsal side and other setae.
(2) Mandibles are inverted: mandible with distally projected mola is right one, and mandible with proximally projected mola is left one. Non-unique apomorphy, the same in selected species among Radulapalpata.
(3) Each tergalius IVII lost fibrillose portion, costal and anal ribs [see Branchitergaliae (3)], has a large anterior-proximal lobe and pointed apex (Edmunds & al. 1986: Fig.54; Studemann & al. 1987: Fig.13).
(4) On fore wing RSa2 lost its connection with RSa and has a form of intercalary, which begins more distally than iRSa (Kluge 2004: Fig.53:C). This apomorphy is not unique, occurs in many Furcatergaliae and Tridentiseta, but never occurs in other Branchitergaliae.
(5) On hind wing MA lacks furcation; thus only two triads are present RS and MP, with a single MA between them [see Euplectoptera (1)] (Kluge 2004: Fig.53:D). Non-unique apomorphy (see Index of characters [2.2.67]); among Pentamerotarsata the same in dimicki [Cinygma].
(6) Imaginal and subimaginal gonostylus with 3 distal segments (instead of two ones initial for Ephemeroptera). Non-unique apomorphy (see Index of characters [2.3.12]).
Characters of Arthroplea of unclear phylogenetic status.
(7) Superlinguae are curved laterally (Studemann & al. 1987: Fig.1516). Probably apomorphy of Pentamerotarsata, as the same in Heptagenia/f5=g4 (but not in other Radulapalpata).
(8) Penis, besides the pair of median titillators [see Pentamerotarsata (5)], with a pair of ventral titillators immovable spines, situated on ventral side proximad of the median titillators (Studemann & al. 1987: Fig.2732).
Plesiomorphies of Arthroplea. Labium and labial palps completely lack that specialization, which is peculiar for Radulapalpata. Unlike Radulapalpata, posterolateral spines are present on abdominal segments IIIX and are enlarged toward segment IX (Studemann & al. 1987: Fig.11). Larval primary swimming setae [vestigial see Pentamerotarsata (6)] are present. Larval and adult patella-tibial suture is developed on middle and hind legs only.
Size. Fore wing length 810 mm.
Nominal species in Arthroplea/fg(1):
bipunctata McDunnough 1924 [Cinygma] --/
congener Bengtsson 1908 [Arthroplea] --/
elegans Bengtsson 1908 [Remipalpus] syn.subj. congener [Arthroplea]
frankenbergi Balthasar 1937 [Arthroplea] syn.subj. congener [Arthroplea]
mirabile Lestage 1924 [Cinygma] syn.subj. congener [Arthroplea]
southi Blair 1929 [Haplogenia] syn.subj. congener [Arthroplea]