Caenis Stephens 1836
Creators: name: Nascimento, Stênio R. S.
name: Rodrigues, Jackson A. O.
name: Ale-Rocha, Rosaly
name: Lima, Lucas R. C.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Ephemeroptera
Caenidae
Caenis

description: Male imagos of Caenis from Brazil (adapted from Domínguez et al. 2006)
1. Apex of the forceps sharp and sclerotized................................................................. 2
- Apex of the forceps rounded........................................................................... 5
2(1). Forceps narrowing gradually toward the apex.............................................................. 3
- Forceps sharpening abruptly at the apex................................................................... 4
3(2). Surface of the forceps without setae with 3 subapical denticles; lobes of the penis fused, without vestige of a dividing groove (Da-Silva, 1993: Fig. 4).................................................................... Caenis cuniana
- Forceps generally with small tubercles and setae on outer basal margin; forceps 7.3–9.5 times longer than width at the middle; apophyses strongly developed, wide and long (Molineri et al. 2011: Figs 3, 5, 6A–F)................... C. teipunensis
4(2). Forceps approximately six times longer than width at half length; about six setae present on ventral surface (Malzacher, 1986: Figs 5B, C, 11)............................................................................ C. candelata
- Forceps approximately 9-11 times longer than width at half length, approximately 15-20 setae present on ventral surface (Malzacher, 1986: Figs 5A, 10).................................................................. C. fittkaui
5(1). Finger-like median process present in abdominal tergum II; fore leg twice as long as hind leg or longer; forceps and sclerites of the genitalia strongly colored........................................................................... 6
- Abdominal tergum II without median projections (but lateral projections may be present); fore leg at most 1.8 times the length of hind leg; forceps and sclerites of the genitalia nearly uncolored)............................................. 7
6(5). Lateral filaments of abdominal segments relatively short; lobes of penis short and laterally rounded; apophyses of the styliger sclerite long and thin, somewhat distanced from the base of the forceps (Malzacher, 2001: Figs 7A–E)...... C. plaumanni
- Central sclerite of styliger elongated; apophyses of styliger sclerite broad and short; penis whitish with rounded lateral lobes (Molineri & Malzacher, 2007: Figs 96–98).......................................................... C. uruzu
7(5). Lobes of the penis totally fused, without a median groove.................................................... 8
- Groove separating the lobes of the penis visible............................................................ 9
8(7). Forceps somewhat curved toward median line; without trichomes or minute spines at apex; posterior margin of styliger plate more or less straight; penis rounded and narrow at the base (Pereira & Da-Silva, 1990: Fig. 2)................ C. cigana
- Forceps curved toward median line, covered with trichomes with 2–3 minute spines at apex; posterior margin of styliger plate short convex; penis square-shaped, not narrow at base.................................. Caenis marataoan sp. nov.
9(7). Penis with laterally protruding lobes.................................................................... 10
- Lobes of penis very short and not or only slightl y protruding................................................ 13
10(9). Posterior margin of styliger plate straight or rounded....................................................... 11
- Posterior margin of styliger plate subtriangular............................................................ 12
11(10). Fore margin of the styliger sclerite convex; apophyses of styliger sclerite bent inwards (Malzacher, 2001: Figs 9A–I).................................................................................................. C. tenella
- Fore margin of the styliger sclerite straight; apophyses of styliger sclerite pointed and straight (Lima et al. 2015b: Figs 1C, D)........................................................................................ C. gaucha
12(10). Apical margin of penis convex; apophyses of the styliger sclerite bent inwardly, fore margin of the styliger sclerite concave (Malzacher, 1990: Figs 1A, B)............................................................... C. pflugfelderi
- Apical margin of penis straight; apophyses of the styliger sclerite pointed and straight, fore margin of the styliger sclerite straight (Alba-Tercedor & Mosquera, 1999: Figs 1, 4)............................................... C. chamie
13(9). Lobes of the penis very short and swollen at base; styliger plate usually covering the penis; prosternal triangle narrow and triangular, usually closed toward apex (Malzacher, 1986: Figs 13A, 16, 18A, B).......................... C. sigillata
- Lobes of the penis relatively long; styliger plate not covering penis; prosternal triangle broad and usually open toward apex .................................................................................................. 14
14(13). Prosternal triangle very broad and open anteriorly; apex of genital forceps rounded with margins ornamented with small wartlike bumps; basal dilation of the antennal bristle about 1.5 times the length of the pedicel (Malzacher, 1986: Figs 12E, 13C, 17, 18C)............................................................................... C. quatipuruica
- Prosternal triangle tapered and open anteriorly; apex of forceps without ornamented margins; basal dilation of the antennal bristle shorter than the length of the pedicel (Malzacher, 1986: Figs 12C, 13B, 15, 18D–F).................... C. reissi
description: Published as part of Nascimento, Stênio R. S., Rodrigues, Jackson A. O., Ale-Rocha, Rosaly & Lima, Lucas R. C., 2022, New species and records of Caenidae Newman, 1853 (Insecta: Ephemeroptera) from Northeastern Brazil, pp. 110-122 in Zootaxa 5133 (1) on pages 119-120, DOI: 10.11646/zootaxa.5133.1.5, http://zenodo.org/record/6521359