Notophyllum, Kato & Pleijel, 2002

Kato, Tetsuya & Pleijel, Fredrik, 2002, A revision of Notophyllum Örsted, 1843 (Phyllodocidae, Polychaeta), Journal of Natural History 36 (10), pp. 1135-1178 : 1172-1175

Phylogeny of Notophyllum

Based on previous phyllodocid phylogenetic analyses (Pleijel, 1991; Eibye- Jacobsen, 1993; Orrhage and Eibye-Jacobsen, 1998) we employed Austrophyllum charcoti (Gravier, 1911) , Clavadoce annenkovae Uschakov, 1950 and Nereiphylla castanea ( Marenzeller, 1879) as outgroups. These studies all agree on the close relationships between Notophyllum , Austrophyllum , Clavadoce and Nereiphylla . Although considered unlikely, the more distant Lacydonia was included in order to test for the possibility that Austrophyllum , Clavadoce and/or Nereiphylla actually are nested within Notophyllum . As Lacydonia appears rst in the matrix, it represents the terminal which actually roots the tree. All eight Notophyllum species listed above were employed as terminals.

Most characters were scored simply as absent–present. Multistate unordered coding was employed for some characters (3, 4, 18, 19) in order to decrease linkage between characters, and follows the C-coding in Pleijel (1995), where inapplicable characters are entered as question marks. A list of characters is provided in table 2 and the matrix in table 3. The analysis was carried out with PAUP* 4.0b4a (SwoOEord, 1993) and MacClade 3.08a ( Maddison and Maddison, 1992). Tree searches were performed with the branch and bound search algorithm and all ‘default settings’.

The analysis yielded ve equally parsimonious trees, with a CI of 0.91 (excluding uninformative characters, i.e. 2 and 8), a RI of 0.96 and a length of 25 steps. We have chosen to illustrate one of the trees, which also is identical to the strict consensus tree (gure 17). As expected, Notophyllum is monophyletic and is supported by nine apomorphies: anterior elongation of prostomium, laterally projecting nuchal organs with dorso-posterior lobes, lateral rows of proboscis papillae, dorso-lateral papillae on proximal part of proboscis, dorsal aciculae in segments 2 and 3, broad reniform dorsal cirri without tips, dorsal reduction of segment 2, and rounded and attened pygidial cirri.

1. Antero-ventral elongation of prostomium: absent 0; present 1.

2. Median antenna: present 0; absent 1.

3. Nuchal organ shape: ridge-like 0; laterally prolonged 1; laterally prolonged with dorso-

posterior lobes 2.

4. Number of nuchal organ lobes: 1–2 0; 3–4 1; 5–6 2;>6 3.

5. Width of proboscis: as prostomium or wider 0; narrower than prostomium 1.

6. Lateral rows of papillae on proboscis: absent 0; present 1.

7. Shape of papillae in lateral rows: rounded 0; discoid 1.

8. Hook-shaped papillae: absent 0; present 1.

9. Dorso-lateral group of papillae on proximal part of proboscis: absent 0; present 1.

10. Size of papillae in dorso-lateral groups on proximal part of proboscis: both large and small 0; large only 1.

11. Ventral tentacular cirri of segment 2: gradually tapered 0: in ated with distinct tips 1.

12. Dorsal aciculae of segment 2: absent 0; present 1.

13. Dorsal aciculae of segment 3: absent 0; present 1.

14. Shape of dorsal cirri: lanceolate to cordiform 0; broad reniform without tips 1.

15. Dorsal aciculae of median segments: present 0; absent 1.

16. Dorsal capillary chaetae of median segments: present 0; absent 1.

17. Dorsally elongated dorsal cirrophores: absent 0; present 1.

18. Dorsal portion of segment 1: large 0; narrower than segment 3 1; invisible 2.

19. Dorsal portion of segment 2: large 0; narrower than segment 3 1; invisible 2.

20. Pygidial cirri: cylindrical 0; rounded and attened 1.

Numbers correspond to matrix in table 3 and cladogram in gure 17. The numbers correspond to characters in table 2 and the cladogram in gure 17. Question marks denote unknown character states or non-applicable characters.

The clade ( N. japonicum , N. multicirris ) constitutes the sister of remaining Notophyllum , but is only supported by having a proboscis that is narrower than the prostomium. Notophyllum sagamianum and N. splendens appear in a trichotomy together with the clade ( N. foliosum , N. americanum , ( N. imajimai , N. imbricatum )). This trichotomy is identi ed by dorsally elongated dorsal cirrophores. As noted earlier, the separation of N. sagamianum and N. splendens warrants further study. The clade ( N. foliosum , N. americanum , ( N. imajimai , N. imbricatum )) is united by having rounded papillae in the lateral rows, by having both small and large dorsolateral papillae proximally on the proboscis, by the presence of notochaetae, and by segment 2 in dorsal view being more narrower than segment 3, and the sister group ( N. imajimai , N. imbricatum ) is characterized by the single character ventral tentacular cirri on segment 2 in ated with distinct tips.

The number of lobes of the nuchal organs has traditionally been employed to identify diOEerent Notophyllum . The results in gure 2, however, indicate a strong relation to size. Clearly, the number of nuchal lobes should not be used in isolation for identi cation of Notophyllum species. Due to extensive overlap between terminals, there is also no cladistic information, apart from the obvious observation that lobes represent an apomorphy for Notophyllum . The fact that the outgroups on the tree become optimized as having nuchal lobes (character 4), whereas they actually lack them, is a side eOEect of scoring them as non-applicable (i.e. question marks) and without other importance.

Biramous versus uniramous parapodia has traditionally been considered a ‘central’ character in polychaete evolution. In Pleijel’s (1991) phyllodocid study, both the presence of notoaciculae and capillary notochaetae came out as plesiomorphies which were retained within Austrophyllum and Notophyllum , and reduced twice, once within Notophyllinae and once in the lineage leading to the remaining Phyllodocidae . In the analyses of Eibye-Jacobsen (1993) and Orrhage and Eibye-Jacobsen (1998), the plesiomorphic state is absence of notoaciculae (notochaetae were not scored), whereas in the present study, the notoaciculae in median segments constitute a plesiomorphy, but the presence of notopodial capillaries is an apomorphy for N. foliosum , N. americanum , N. imajimai and N. imbricatum . Uni- and biramous parapodia exhibit large degrees of homoplasy in the polychaete trees, and the phyllodocids are no exception.

Our analysis accordingly indicates two well-supported groups. One is Notophyllum , and the other is a subgroup of Notophyllum which includes N. foliosum , N. americanum , N. imajimai and N. imbricatum . Nevertheless, we see at present no obvious need for introducing a new name for this latter group, and currently leave both this and other subparts of Notophyllum unnamed.