OWENIIDAE RIOJA, 1917 FROM

Ibrahim, Nur Fazne, Villalobos-Guerrero, Tulio F. & Idris, Izwandy, 2024, Review of Oweniidae Rioja, 1917 (Annelida, Palaeoannelida) from Malaysia, with a description of two new species and a key to South China Sea species, Zoosystema 46 (20), pp. 513-542 : 522

KEY TO THE GENERA AND SPECIES OF OWENIIDAE RIOJA, 1917 FROM THE SOUTH CHINA SEA (SCS)

1. Head with a crown of tentacles................................................................... Owenia Delle Chiaje, 1844 ....... 3

— Head without of a crown of tentacles .......................................................................................................... 2

2. Truncated head; groove present between first and second segments; mouth with mid-ventral slit forming large lateral lips ........................................................................................... Galathowenia Kirkegaard, 1959 ..... 5

— Rounded head; groove absent between first and second segments; button-hole-shaped mouth with low lips around .................................................................................................... Myriochele Malmgren, 1867 ...... 6

3. Tentacular crown with four pairs of long dichotomies and multi-branched tentacles; crown three-quarters as long, or as long as uniramous segment ........................................................................................................ 4

— Tentacular crown with three pairs of short dichotomies and poorly-branched tentacles; crown half as long as uniramous segment ........................................................................................................ O. unipinnata n. sp.

4. Cephalic region with prominent membranous collar; pygidium with 10 or more lobes surrounding anus; no lateroventral eyespots .......................................................................................... O. collaris ( Hartman, 1955)

— Cephalic region with barely conspicuous collar; pygidium with two lobes; presence of lateroventral eyespots ... ................................................................................................................... O. fusiformis ( Delle Chiaje, 1844)

5. No lateroventral eyespots; pygidium with eight or more finger-like lobes surrounding anus; dwelling in deep waters ........................................................................................................ G. lobopygidiata ( Uschakov, 1950)

— Presence of lateroventral eyespots; pygidium with only two blunt lobes; dwelling in shallow water ................. ............................................................................................................................................. G. minuta n. sp.

6. Tubes with accumulations of sponge spicules, foraminiferans or shell fragments exclusively; long size (15-20 mm, 25 segments); calibrated and aligned spicules, dwelling in deep water ..................... M. minor Caullery, 1944

— Tubes with accumulations of sand grains exclusively; short size (3-4 mm, 16 segments); dwelling in estuarine waters ...................................................................................................................... M. picta Southern, 1921