Rhopyscelis, Cruza & Sallesb & Hamada, 2020

Cruz, Paulo Vilela, Salles, Frederico Falcão & Hamada, Neusa, 2020, A cladistic approach for generic delimitation of Paracloeodes Day, Rivudiva Lugo-Ortiz & McCafferty, and Varipes Lugo-Ortiz & McCafferty (Ephemeroptera: Baetidae), Insect Systematics & Evolution 51 (2), pp. 256-275 : 269-272

Rhopyscelis gen. n.

ZooBank: http://zoobank.org/ 46753411-F21E-45AE-BC10-8397138F68A4

Type species: Varipes singuil Nieto 2004 (original designation)

Etymology. The generic name is an arbitrary combination of the Greek words rhop (brush) and scelis (leg), an allusion to the many long femoral setae on both species allocated to the new genus. The gender is feminine.

Composition. Rhopyscelis singuil ( Nieto 2004) comb. n. (type species) and Rhopyscelis caldensis ( Gutiérrez, Dias & Salles 2013) comb. n.

Diagnosis. Male imago. 1) forewing hyaline ( Fig. 30 in Nieto 2004); 2) marginal intercalary veins paired ( Fig. 30 in Nieto 2004); 3) hind wing absent; 4) subgenital plate without apical spine ( Fig. 31 in Nieto 2004); 5) first segment of forceps with inner projection ( Fig. 31 in Nieto 2004); 6) last segment of forceps rod-like ( Fig. 31 in Nieto 2004).

Mature nymph. 1) prostheca of right mandible slender and bifid ( Fig. 34 in Nieto 2004); 2) mandibular incisors partially fused ( Fig. 34 in Nieto 2004); 3) inner set of incisors at right angle to the outer set; 4) distomedial projection of labial palp segment II rounded ( Fig. 7 in Gutiérrez et al. 2013; Fig. 37 in Nieto 2004); 5) segment III of labial palp conical (apex broadly pointed) ( Fig. 7 in Gutiérrez et al. 2013; Fig. 37 in Nieto 2004); 6) trochanter inserted along entire base of femur ( Fig. 15 ; Fig. 11 in Gutiérrez et al. 2013; Fig. 38 in Nieto 2004); 7) many long thin femoral setae ( Figs. 19–22 ); 8) vestigial transverse row of long setae on proximal third of forefemur ( Figs. 19 and 20 ); 9) mid and hind femora with transversal row of long setae on proximal third ( Figs. 20 and 22 ); 10) sockets of transverse row of setae on the mid and hind femora not touching each other ( Figs. 23 ); 11) two rows of denticles on foreclaw apically directed ( Figs. 25–27 ); 12) hind wing pads absent; 13) gill I-VII not racquetshaped; 14) abdominal terga surface creased, without scale-like setae/socket.

Description

Male imago. Head. Dorsal portion of compound eyes oval ( Fig. 29 in Nieto 2004); stalk in lateral view of dorsal portion of compound eye divergent. Thorax. Forewing hyaline with paired marginal intercalary veins ( Fig. 30 in Nieto 2004); length of each intercalary vein 0.5 × distance between adjacent longitudinal veins ( Fig. 30 in Nieto 2004). Hind wing absent. Abdomen. Genitalia ( Fig. 31 in Nieto 2004). Forceps segment II narrow medially; segment III rod-like.

Mature nymph. Head. Frons with two longitudinal keels. Antenna with spines and simple setae. Labrum ( Fig. 32 in Nieto 2004; Fig. 2 in Gutiérrez et al. 2013) with bifid setae on distoventral arc; bifid setae on distomedial arc; mediodorsal arc of setae present and extending laterally; and absence of pair of denticles on the medial emargination. Right mandible ( Fig. 34 in Nieto 2004; Fig. 4 in Gutiérrez et al. 2013) with external margin convex; prostheca slender and bifid; incisors partially fused; and inner set of incisors at right angle with outer set. Left mandible ( Fig. 33 in Nieto 2004; Fig. 3 in Gutiérrez et al. 2013) with external margin of mandibles convex; prostheca stout; molars with constriction; incisors partially fused; inner set of incisors at right angle with outer set. Maxilla ( Fig. 36 in Nieto 2004; Fig. 6 in Gutiérrez et al. 2013) innerdorsal margin with two rows of setae; first dentiseta more robust than others; first dentiseta not coupling with canine at base ( Fig. 10 ); palp with two segments. Labium (Fig. 37 in Nieto 2004; Fig. 7 in Gutiérrez et al. 2013) with elongate mentum; base of glossa not overlapping the base of paraglossa; paraglossa subtriangular; distomedial projection of labial palp segment II rounded; segment III of labial palp conical (apex broadly pointed). Thorax. Hind wing pad absent. Legs ( Fig. 22 ) with trochanter insert- ed along entire base of femur; many long and thin setae on femora; vestigial transverse row of long setae on proximal third of forefemur; mid and hind femora with transverse row of long setae on proximal third; sockets of setae on the mid and hind transverse rows not touching each other; two rows of denticles on the claws; foreclaw denticles apically directed; denticles triangular. Abdomen. Gills on segment I–VII without folds, gill I not racquet-shaped; posterior margin of terga with spines; abdominal terga surface creased, without scale-like setae/socket; terminal filament subequal in length than cerci; caudal filaments with spines on each segment.

Distribution: Argentina and Colombia.

Comments

Considering the topology, the position of ( P. caldensis + V. singuil ) corroborated its placement in Varipes as subgenus or a new genus; in a broad sense, Gen. A could also belong to Varipes . However, evaluating the stability of the clades, Varipes (narrow sense) + ( P. caldensis + V. singuil ) is a weakly supported clade, while ( P. caldensis + V. singuil ) and Varipes have high values of the indices and, in the case of Varipes , a large number of synapomorphies. Gen. A + ( P. caldensis + V. singuil ) + Varipes ) is a weakly supported clade, while Gen. A, ( P. caldensis + V. singuil ) and Varipes are three well-supported groups. Analytical settings were varied to verify the robustness of these monophyletic groups (see Materials and Methods section). All topologies resulting from these exploratory searches recovered Gen. A, ( P. caldensis + V. singuil ), Rivudiva , Varipes , and Paracloeodes as well-supported and stable monophyletic groups.

In addition to the highly stable monophyletic groups and the understanding that the long setae state is an independent acquisition between groups, a large number of generic characteristics was obtained in morphological analyses (some of them treated as characters and states in the matrix). Those attributed to P. caldensis and V. singuil have proved to be very effective in differentiating both of these species, not only from Varipes , but also from all other Neotropical and Nearctic genera as follows: scape and pedicel without scale-like tubercles in P. caldensis + V. singuil , while present in Varipes ; mandibular incisors partially fused in P. caldensis + V. singuil , while fused in Varipes ; inner set of incisors at right angle to the outer set in P. caldensis + V. singuil , while in the same plane in Varipes ; maxilla with the first dentiseta with the same robustness as the others and with its basal projection not coupling with canine in P. caldensis + V. singuil , while the first dentiseta is more robust than the others and with base coupling with canine in Varipes ; segment III of labial palp semi conical (apex broadly pointed) in P. caldensis + V. singuil , while globose in Varipes ; base of glossa not overlapping base of paraglossa in P. caldensis + V. singuil , while overlapping in Varipes ; lingua with distomedial projection in P. caldensis + V. singuil , while absent in Varipes ; dorsal margin of femora parallel to ventral in P. caldensis + V. singuil , while convex in Varipes ; trochanter inserted along entire base of femur in P. caldensis + V. singuil , while at the base of femur in Varipes ; vestigial transverse row of long setae on proximal third of forefemur in P. caldensis + V. singuil , while not vestigial in Varipes ; mid and hind femora with transverse row of long setae on proximal third with sockets not touching each other in P.caldensis + V. singuil , while touching each other in Varipes ; tibio-patelar suture with length equal or less than one third of tibia in P. caldensis + V. singuil , while equal or more than a half of tibia in Varipes ; claws with triangular and apically directed denticles starting at base in P. caldensis + V. singuil , while conical, perpendicular and starting at medial third in Varipes ; gill I symmetrical in P. caldensis + V. singuil , while racquet-shaped in Varipes .

P. caldensis + V. singuil could also be confused with the Nearctic genus Kirmaushenkreena McCafferty , mainly based on long setae on forefemur and claws with symmetrical rows of denticles (key of Waltz & Burian, 2008). The genus Kirmaushenkreena can be differentiated from P. caldensis + V. singuil , among other characteristics, by the presence of a subapical pair of setae on claws, while is absent in P. caldensis + V. singuil ; the first dentiseta with its base coupling with canine, while not coupling in P.caldensis + V. singuil ; and transverse row of setae on femora absent, while present in P. caldensis + V. singuil .

Taking into account the phylogenetic position, the number of synapomorphies, clade stability, and the great number of generic characteristics that differentiate the P. caldensis + V. singuil clade from other genera in the Nearctic and Neotropical realms, we propose this clade as a new genus, Rhopyscelis gen. n., described and diagnosed above.

Figures

Figs. 16–30. 16, detail of forefemur concave setae on dorsal margin (Paracloeodes atroari) Char. 77; 17, detail of forefemur, black arrow indicates the FLRNDM = forefemur longitudinal row of setae near dorsal margin on anterior surface (Paracloeodes eurybranchus) Char. 80; 18, detail of forefemur, black arrow indicates the FLRNML = forefemur longitudinal row of setae at middle on anterior surface (Paracloeodes sp.) Char. 82; 19, anterior surface of forefemur, black arrow indicates the vestigial row of setae, (Rhopyscelis singuil comb. n.) Char. 85 and 86; 20, anterior surface of hind femur, black arrow indicates the transversal row of setae, (Rhopyscelis singuil comb. n.) Chars 89 and 90; 21, anterior surface of forefemur, black arrow indicates the vestigial row of setae, (Rhopyscelis caldensis comb. n.) Chars 85 and 86; 22, anterior surface of hind femur, black arrow indicates the transversal row of setae, (Rhopyscelis caldensis comb. n.) Chars 89 and 90; 23, detail of transversal row of setae on hind femur, (Rivudiva trichobasis) Chars 89 and 91; 24, detail of transversal row of setae on hind femur, (Varipes helenae) Chars 89 and 91; 25, foreclaw, black arrow indicates the denticles apically directed (Rhopyscelis singuil comb. n.) Chars 96–101; 26, foreclaw, black arrow indicates the denticles apically directed (Rhopyscelis caldensis comb. n.) Chars 96–101; 27, hind claw, black arrow indicates the denticles apically directed (Rhopyscelis caldensis comb. n.) Chars 96– 101; 28, hind claw, black arrows indicate the regularity of row of denticles, (Rivudiva trichobasis) Chars 99 and 102; 29, foreclaw, black arrow indicates the absence of denticles on base, red arrow indicates the conical and apical denticles, (Varipes lasiobrachius) Chars 106 and 107; 30, detail of foreclaw, black arrow indicates apical denticles on claw extremely higher than the others (Gen. A.) Char. 104.

Figs. 31–36. 31, genitalia, black arrows indicate the unistyliger inner projection (Paracloeodes sp.) Chars 142–149; 32, genitalia, black arrow indicates the spine and convex subgenital plate (Paracloeodes atroari) Chars 142–149; 33, genitalia, black arrow indicates the rounded apex of subgenital plate (Callibaetis sp.) Chars 142–149; 34, genitalia, black arrow indicates the concave subgenital plate (Paracloeodes sp.) Chars 142–149; 35, genitalia, black arrow indicates the rounded apex of subgenital plate (Callibaetis capixaba) Chars 142–149; 36, genitalia, black arrow indicates the triangular subgenital plate (Apobaetis fiuzai) Chars 142–149, adapted from Cruz et al. 2011.

Figs. 2–15. 2, elevation of frons with two keels (Paracloeodes charrua), Chars 1 and 2, black arrow indicates frons; 3, elevation of frons with one keel (Paracloeodes atroari) Chars 1 and 2, black arrow indicates frons; 4, organization of setae on labrum (Callibaetis capixaba, left = dorsal, right = ventral) Chars 5, 6, 8, 15, 16, 19, 20, LAS = lateral arc of setae, DAS = distal arc of setae, DMA = distomedial arc of setae, SDA = subdistal arc of setae on ventral surface, MDA = mediodorsal arc of setae, RSVL = ventral row of spine-like setae on lateral margin of labrum, TSVALM = tuft of setae ventrally on anterolateral margin of labrum; 5, organization of setae on labrum (Apobaetis sp.) Chars 10, 14, DDA = distodorsal arc of setae, SDMA = sub-distomedial arc of setae on dorsal surface; 6, organization of setae on labrum (Waltzoyphius sp.) Char. 12, SDLA = sub-distolateral arc of setae on dorsal surface; 7, detail of deep cleft incisors of right mandible (Callibaetis sp.) Char. 30, black arrow indicates the incisors; 8, detail of partially fused incisors of right mandible (Paracloeodes sp.) Char. 30, black arrow indicates the incisors; 9, detail of a small lobe on apex of last segment of maxillary palp (Rivudiva sp.) Char. 43, back arrow indicates the lobe; 10, detail of basal projection of first dentiseta coupling with canine on maxilla (Varipes lasiobranchius) Char. 47; 11, detail of row of setae on outer margin of paraglossa (ROMP) (Callibaetis sp.) Char. 59; 12, detail of labial palp with red lines showing axes for angle measure (Apobaetis sp.) Char. 65; 13, detail of labial palp segment II and III, black arrow indicates the medial concavity on segment III (Callibaetis calloventer) Char. 68; 14, detail of trochanter inserted on ventral margin of femur, red line shows the connection (Varipes lasiobrachius) Char. 73; 15, trochanter inserted along entire base of femur, red line shows the connection (Rhopyscelis caldensis comb. n.) Char. 73.