Leptopentacta H. L. Clark 1938

Key to the genera Leptopentacta (s.s.) and Paraleptopentacta n. gen and their species

1. Calcareous ring with posteriorly forked radial plates always in combination with large multi-layered, reticulated plates or lenslike bodies as major body wall deposits; Indo-Pacific forms...................................... Leptopentacta... 2

- Calcareous ring usually with unforked radial plates in combination with usually large unreticulated, smooth plates made up of a single layer of calcareous material, as major body wall deposits; Mediterranean and North-West Atlantic forms...................................................................................... Paraleptopentacta n. gen.... 7

2. External layer of deposits exclude baskets or rosettes of any form............................................... 3

- External layer of deposits include baskets or rosettes or both................................................... 4

3. Tube feet rigid, non-retractile; only small knobbed buttons present in addition to reticulated plates......... L. bacilliformis

- Tube feet retractile; knobbed buttons present; plates complex with reticulated bars (species known only from juveniles)................................................................................................... L. nina

4. External layer of ossicles as rosettes developed from baskets, complete baskets often present in addition to rosettes, perhaps in juveniles only............................................................................... L. imbricata

- External layer of ossicles only as baskets................................................................... 5

5. Baskets deep, cup-like; plates as lens-like, reticulated bodies; smaller, smooth plates and knobbed buttons with large holes also present........................................................................................ L. grisea

- Baskets also deep, cup-like; large plates reticulated but not appearing as lenticular or lens-like bodies; other plates also present but also non-lenticular; buttons present.................................................................... 6

6. Some baskets rosette-like; buttons knobbed with small holes; reticulate plates never with a protruding spine..................................................................................................... L. punctabipedia

- Baskets deep, cup-like; sometimes both baskets and plates provided with a protruding spine................. L. panamica

7. Plates smooth, simple, multilocular, of several sizes, rarely imbricating; baskets numerous, variable.................... 8

- Plates of various forms, rarely one or two reticulate; baskets flat, with trabeculae, margins slightly knobbed...... P. cucumis

8. Baskets large, with numerous marginal projections, buttons absent from body wall; large plates smooth................. 9

- Baskets tiny but also with numerous projections; buttons also tiny, knobbed, holes minute; large plates knobbed..................................................................................................... P. djakonovi

9. Plates smooth, imbricating; baskets with tiny projections and sometimes multilocular base; plates of various sizes but never narrow and elongate, holes large; rosettes absent..................................................... P. elongata

- Plates not imbricating, smooth, of various sizes, often narrow with usually two series of small holes; baskets cup-like, with numerous projections in various directions; rosettes also present............................... P. tergestina n. comb.