Caenis Stephens, 1835

Srinivasan, Pandiarajan, Sivaruban, T., Barathy, S. & Isack, Rajasekaran, 2023, Contribution to the knowledge of family Caenidae (Insecta: Ephemeroptera) from Madurai District, Tamil Nadu, Zootaxa 5258 (1), pp. 39-75 : 73

Key to the known larvae of Caenis Stephens, 1835 from South India

(Larval characters of Caenis maratha , Caenis sp. 1 , and Caenis sp. 2 are unknown)

1 Cuticular coloration of femora, tibia and tarsus of each leg with contrasting dark bands ( Fig. 129 )... C. arunachalami sp. n.

- Cuticular coloration of femora, tibia and tarsus of each leg mostly unicolor without any contrasting dark band ( Fig. 3 )..... 2

2 Mesonotum with well-developed bulging at the margins ( Fig. 2 )...................................... C. americani

- Mesonotum with slightly-developed or no bulging at the margins ( Fig. 79 )........................................ 3

3 Foreclaw and midclaw without any denticulation ( Figs. 80 , 85 )................................................. 4

- Foreclaw and midclaw with denticles ( Figs. 41 , 44 ).......................................................... 5

4 Hindclaw without any basal denticles along with row of microdenticles ( Fig. 13 )...................... C. maduraiensis

- Hindclaw with basal denticles along with row of microdenticles ( Fig. 91 )...................... C. venkataramani sp. n.

5 Forefemur with a transverse row of 12–13 spatulate setae ( Srinivasan et al. 2023; Fig. 22 )...................... C. limai

- Forefemur with a transverse row of 7–8 spatulate setae ( Fig. 38 ).................................... C. kaegies sp. n.

Figures

FIGURES 129–131. Larval exuvia of Caenis arunachalami sp. n.: (129) hindleg; (130) hindtarsus setation; (131) hindclaw.

FIGURES 1–3. Caenis americani Srinivasan et al. 2021: (1) female imago; (2) head and thorax of larval exuvia (arrows indicate bulging in mesonotum); (3) hindleg of larval exuvia.

FIGURES 76–80. Larval exuvia of Caenis venkataramani sp. n.: (76) maxilla; (77) labium; (78) paraglossa and labial palp; (79) mesonotum; (80) foreclaw.

FIGURES 85–91. Larval exuvia of Caenis venkataramani sp. n.: (85) midclaw; (86) hindfemur; (87) hindtibia and tarus; (88) hindtibia setation; (89) hindtarsus setation; (90) hindclaw; (91) closer view of hindclaw (arrow indicates three minute basal denticles).

FIGURES 38–41. Larval exuvia of Caenis kaegies sp. n.: (38) foreleg; (39) transverse row of setation in forefemur; (40) foretibia setation; (41) foreclaw.

FIGURES 42–44. Larval exuvia of Caenis kaegies sp. n.: (42) midleg; (43) midtibia setation; (44) midclaw.

FIGURES 8–15. Caenis maduraiensis Balasubramanian and Muthukatturaja, 2021: (8) male imago (holotype); (9) head of male imago; (10) forceps; (11) forefemur of larval exuvia; (12) hindfemur of larval exuvia; (13) hindclaw; (14) sternum IX of male larval exuvia; (15) shagreen field in the dorsal surface of sternum IX.

FIGURES 20–23. Male imago of Caenis kaegies sp. n.: (20) dorsal view; (21) lateral view; (22) abdominal terga; (23) head, dorsal view.