30 November 1988 Memoirs of the Museum of Victoria 49(2): 385-431 (1988) ISSN 0814-1827 https://doi.org/10.24199/j.mmv.1988.49.17 A REVIEW OF ETEONE SAVIGNY, 1820, MYSTA MALMGREN, 1865 AND HYPERETEONE BERGSTROM, 1914 (POLYCHAETA: PHYLLODOCIDAE) By Robin S. Wilson Museum of Victoria, Swanston Street, Melbourne, Victoria 3000, Australia Abstract Wilson, R.S. 1988. A review of £reone Savigny, 1820, Mysta Malmgren, 1865 and Hypereteone Bergstrom, 1914 (Polychaeta: Phyllodocidae). Memoirs of the Museum of Victoria 49: 385-431. 1914 is Eteone sensu lato is reviewed and three genera recognised: Hypereteone Bergstrom, resurrected and redefined; Mysta Malmgren, 1865 is retained unchanged and Eteone Savigny, comprises nine nominal 1820 is redefined to include all remaining species. Hypereteone now species including H. otati and H. tingara which are described as new species. An apparently baran- undescribed species of Hypereteone is also recognised and H. alba (Webster, 1879), H. (Quatrefages, 1865), toiiae (Fauvel, 1932), H. fauchaldi (Kravitz and Jones, 1979), H. fotiosa combina- H. heteropoda (Hartman, 1951) and H. iighti (Hartman, 1936a) are proposed as new platycephala tions. Mysta now includes seven nominal species and one undescribed form, and M. stricto includes 28 nomi- (Augener, 1913) is proposed as a new combination. Eteone sensu now E. tulua are described nal specie's of which four are designated nomina dubia. Eteone palari and well-described species as new species. Keys are provided to distinguish the three genera and all in a separate key. within each genus. Australian species in all three genera are distinguished taxa, Introduction Hypereteone appear to be monophyletic Eteone may be paraphyletic since it is characterised which define related Phyllodocid polychaetes with two pairs of ten- by absence of the characters ten- (the heterogeneity of structures, particularly tacular cirri on the first segment and lacking taxa placed proboscis and setae, seen within species of Eteone tacular cirri on subsequent segments were indication that this genus does not by Bergstrom (1914) in three genera: Eteone is further natural taxon). Savigny, 1820 (species with setae and neuropodia represent a proboscis lack- The classification of the Phyllodocidae proposed on the first post-tentacular segment, (setae Bergstrom (1914) placed Eteone, Hypereteone ing rows of papillae); Mysta Malmgren, 1865 by in the subfamily Eteoninae, together and neuropodia on first post-tentacular segment, and Mysta Pseudomystides (which differs from the three proboscis with two lateral rows of large papillae); with here in having three pairs of tentacu- and Hypereteone Bergstrom, 1914 (first post- genera treated arranged on two segments) and Pelagobia tentacular segment without setae or neuropodia, lar cirri placed in the family Lopadorhynchidae proboscis lacking rows of papillae). Most subse- (now 1977)). Bergstrom's subfamilial classifi- quent authors have retained Mysta as a distinct (Fauchald, Eteone cation has been rejected by most recent authors genus (Fauchald, 1977) or subgenus of Uschakov, 1974) as not phylogenetically valid, (Uschakov, 1974; Hartmann-Schroder, 1971) (e.g. the three genera treated in this paper whereas Hypereteone has been synonymised with however defined by Hartmann-Schroder clearly represent a natural group, being Eteone by all authors except an arrangement of tentacular cirri which is unique (1971). genus-group is arrived at a in the family. The term Eteone course of this study I have In the to with only employed here for the convenience of referring revised generic classification of species segment). all three genera. two pairs of tentacular cirri (on the first attempted a strictly phylogenetrc arrangement best represents the I have not I believe this both because is arrangement of genera and species, relationships within the group. Mysta natural inadequate but also Hypereteone is the material of many species is retained as defined by Bergstrom, it is not pos- anal because present knowledge is such that revised to include all species with long tapered cladistic analysis. (It is not clear all remain- sible to carry out a cirri, and Eteone sensu stricto contains Mysta and which taxa would provide appropriate outgroup(s) ing species. In this scheme, although 385 386 R. S. WILSON to establish character polarities, and as set out hypothesises a primitive phyllodocid in which all below, ontogenetic evidence appears to be uninfor- segments are similar; subsequently anterior seg- mative in this family.) The following comments, ments one by one lost their setae and the dorsal which include a summary of the views of Uschakov and ventral cirri were transformed into long ten- (1974), are pertineni to this and future studies of tacular cirri. Finally, in some forms one or more the relationships of these genera. All authors agree anterior segments became fused and some tentacu- that the degree of fusion and the number of lar cirri were lost. Thus the position of the Eteone appendages o( anterior segments are of critical genus-group could be primitive (having only the importance in arriving at a natural classification first segment modified, as suggested by I schakov) of genera. Bergstrom proposed that the evolution- or advanced (having been derived by fusion of ary trend in the family was towards fusion of anterior segments and loss of tentacular cirri from anterior segments and loss of aciculae, setae and forms with several anterior segments modified, as tentacular cirri. The inference was that an addi- proposed b> Bergstrom). The question can Only be tional anterior segment (carrying an additional pair resolved if the two pairs of tentacular cirri of the of tentacular cirri) was present in the primitive form Eteone genus-group can be identified with homolo- and that the Eteone genus-group represents an gous cirri in other genera, possibly through histo- advanced condition, having lost the first segment logical study of the nervous system. and first pair of tentacular cirri, setae and acicu- Questions relating to phyllodocid phytogeny and lae from the second segment, and dorsal cirri from the identity of poorly described species are unlikely the third segment (of the primitive form). Beig- to be full) resolved if only type material is studied. strom's views were based in part on anatomical ( arefully collected, narcotised and preserved speci- study of the anterior nervous system: this appears mens with probosces fully everted are required to to be a valid method of establishing homologies. adequately describe taxonomically important struc- however I have found it impossible to observe any tures, especially in small specimens. This will be detail of the nervous system in my dissections particularly important if histological techniques are As set out fully by Wiley (1981), morphological utilised to aid study of the anterior nervous svstem. change during ontogeny can be interpreted as pass Materials and methods ing through a series of plesiomorphic (primitive) character states prior to reaching the terminal Morphological descriptions in this review gener- derived condition. Thus Uschakov ( 1974) has noted ally recognise the importance of characters that metatrochophore larvae ot the Eteone genus- described by earlier workers. Two exceptions are group already possess a single anteiioi segment with the form of the anal cirri, which I consider to be two pairs of tentacular cirri and inferred that this of generic significance although description of anal was the primitive condition. However, Nolle (1938) cirri is omitted from many earlier descriptions; and has published figures of larvae of several phyl- the head of the setal shaft at the articulation of the lodocid genera which invariably show that the blade, which provides characters which assist in dis- arrangement o\ tentacular cirri found in adults is tinguishing species. Where possible I have examined already present in metatrochophores. Similarly, setae from the same specimen under both light Cazaux (1985) has described and figured the larval microscope and scanning electron microscope stages of Mysttt picta from the Bay of Arachon (in (SEM). The setae are too small to resolve fine detail the Bay of Biscay), showing that two pairs of ten- of the small teeth on the shaft (at the point of artic- tacular cirri appear at the metatrochophore II stage ulation with the blade) with light microscopy, (s setigers) and that earlier larval stages lack ten- however the setae are partly transparent under the tacular cirri entirely. Cazaux also provided a table light microscope and the useful specific character comparing larval development in PhyUodoce, Eula- of the relative size of the large teeth (equal or une- lia and Eteone: in each genus the adult condition qual in si/e) is best observed in this way. SEM appears at the metatrochophore II stage and no examination is essential if the fine structure is to primitive arrangements of tentacular cirri are recog- be seen, but can wrongly indicate that only one nisable. Ontogenetic evidence, though arguably not large tooth is present unless coupled with light sufficient in itself to establish character polarities microscopy. SEM preparations for this paper are (since neoteny cannot be excluded), nevertheless mostly from type material, thus only one or two does not contribute to the debate as to which parapodia could be removed for examination. arrangement of tentacular cirri is the most Individual parapodia were subjected to ultrasonic primitive. cleaning for