Key to Erenna species based on their Type A bracts

1 Largest bracts> 35 mm in length......................................................................... 2

- Largest bracts <35 mm in length......................................................................... 3

2 Mature bracts with complete transverse ridge between proximal pair of cusps; elongate patch of cells, including nematocysts, distally........................................................................ Erenna cornuta Pugh, 2001

- Bracts without transverse ridge between proximal pair of distinctly asymmetrical cusps; large squarish distal patch of cells................................................................................... Erenna insidiator sp. nov.

3 Bracts with one of proximal cusps forming a distinct flap............................... Erenna laciniata Pugh, 2001

- Bracts without distinct flap formed by one of proximal cusps.................................................. 4

4 Bracts relatively narrow. Proximal pair of cusps symmetrical, 13–14 mm from proximal end of bract.................................................................................................. Erenna richardi Bedot, 1904

- Bracts relatively broad. Proximal pair of cusps distinctly asymmetrical......................... Erenna sirena sp. nov.