Magelona

Mortimer, Kate, 2010, Magelonidae (Polychaeta) from the Arabian Peninsula: a review of known species, with notes on Magelona tinae from Thailand, Zootaxa 2628, pp. 1-26 : 23-24

Key to adult specimens of Magelona from the western Indian Ocean

The western Indian Ocean is regarded here as including the seas around the Arabian Peninsula, the seas surrounding east Africa to its southern tip (including Seychelles), and those surrounding Pakistan and western India. The species included here are those known to occur in this region and are included in the following key (unconfirmed records have been omitted), confirmed localities are given for each species:

1. Prostomium with conspicuous, well–delineated frontal horns ..................................................................................... 2

- Prostomium without horns, or rudimentary horns present ........................................................................................... 5

2. Anterior margin crenulate............................................................................................................................................ 3

- Anterior margin smooth................................................................................................................................................ 4

3. Abdominal hooded hooks bidentate, unstained V shape present on venter of mid–thorax, when stained with methyl green ............................................................................................................................ M. crenulifrons (Gulf of Oman)

- Abdominal hooded hooks tridentate ................................................................................... M. cornuta (Gulf of Oman)

4 Abdominal hooded hooks bidentate, unstained X shape present on venter of mid–thorax when stained with methyl green ................................................................................................................................... M. pulchella (Arabian Gulf)

- Abdominal hooded hooks tridentate, distinctive swollen bud-like tips on the notopodial lamellae of chaetiger 9 ....... ................................................................................................... M. gemmata Mortimer & Mackie, 2003 ( Seychelles)

5. Thoracic notopodia with dorsal processes ................................................................................................................... 6

- Dorsal processes lacking ............................................................................................................................................. 8

6. Anterior abdomen with lateral pouches, chaetiger 9 with modified chaetae................................................................ 7

- No anterior abdominal pouches, chaetiger 9 with capillary chaetae; prostomium onion–shaped with rudimentary horns ............................................................................................. M. cepiceps Mortimer & Mackie, 2006 ( Seychelles)

7. Abdominal hooded hooks bidentate; notopodial dorsal processes absent in anterior thorax ......................................... ..................................................................................................... M. conversa Mortimer& Mackie, 2003 ( Seychelles)

- Abdominal hooded hooks tridentate; notopodial dorsal processes on all thoracic chaetigers........................................ .................................................................................................. M. obockensis (Gulf of Aden, Red Sea, Arabian Gulf)

8. Anterior abdominal chaetigers with greatly enlarged re–curved hooded hooks ........................................................... ..................................................................................................... M. falcifera Mortimer & Mackie, 2003 ( Seychelles)

- No enlarged hooks ...................................................................................................................................................... 9

9. Neuropodial lamellae of chaetigers 1–4 expanded distally, scoop–shaped; pigment band present in anterior abdomen ................................................................................................................................................. M. cincta ( South Africa)

- Thoracic neuropodial lamellae not distally expanded .............................................................................................. 10

10. Thoracic notopodial postchaetal lamellae larger than neuropodial ones; neuropodial lobes reduced in size in mid– thorax .......................................................................................... M. mahensis Mortimer & Mackie, 2006 ( Seychelles)

- Thoracic postchaetal lamellae in both rami similar in size and shape........................................................................ 11

11. Postchaetal lamellae in thorax and abdomen long, sharply triangular; large, stout species ........................................... ................................................................................................ M. symmetrica Mortimer & Mackie, 2006 ( Seychelles)

- Thoracic postchaetal lamellae short, triangular; abdominal lamellae lanceolate, basally constricted; small, slender species .................................................................................................................................... M. pygmaea ( Seychelles)