~oologicalj'ournal athe Linnean Sociep (1997), 119: 473-500. With 16 figures
Generic interrelationships within the Spionidae (Annelida: Polychaeta) Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021
ELIN SIGVALDAD~TTIR
Department of ANDREW S.Y. MACKIE Department of AND FREDRIK PLEIJEL Swedish Museum of Natural Histoy, Box 50007, S-104 05 Stockholm, Sweden2 Received December 1995; acceptedfor publication September 1996 The phylogenetic relationships of spionid genera are estimated from parsimony analyses of morphological characters, with Trochochaetidae, Poecilochaetidae and Uncispionidae as outgroups. A first analysis of currently recognised genera proved inconclusive and even exclusion of six of the most polymorphic genera resulted in 13 305 equally parsimonious trees and a fully collapsed consensus tree. A second analysis using only the type species of each genus, yielded four equally parsimonious trees; reduced to two after successive weighting. The topologies of these two trees indicated division of the family into four main groups: (1) Aonidella and Xandaros; (2) Aionospio (sensu lato)-complex, Laonice, Spiophanes and Aonides; (3) a large assemblage of genera, including Po&dwa-(smlab), Scolelepis, Malacocems and Sp;O; (4) Ahemspio, Pseudatherospio and &gospiopsis. Earlier literature classifications of the group are evaluated and compared with the new results. 0 1997 The Linnean Society of London ADDITIONAL KEY WORDS:--cladistics - systematics - parsimony. CONTENTS Introduction ...... 474 Material and methods ...... 474 Ingroup taxa ...... 474 Outgroup taxa ...... 475 Characters ...... 475 ' Correspondence to E. Sigvaldadbttir, present address: Swedish Museum of Natural History, Box 50007, S-104 05 Stockholm, Sweden 'Address for correspondence: Tjtimo Marine Biological Laboratory, P1. 2781, S-452 96 Stromstad, Sweden 473 002+4082/97/040473 + 28 $25.00/0/zj960074 0 1997 The Linnean Society of London 474 E. SIGV.UDADOTTIR ETAL. Parsimony analyses ...... 486 Results and discussion ...... 487 Generic analysis ...... 487 Type species analysis ...... 487 Weighted ty-pe species analysis ...... 49 1 Historical comparisons ...... 494 Conclusion ...... 496 Acknowledgements ...... 497 Refcrences ...... 497 Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 INTRODUCTION The Spionidae Grube, 1850, is one of the major polychaete families, with well over 1000 described species distributed among some 33 currently recognized genera. New additions recgularly appear in the polychaete literature. The group has a worldwide distribution, and is commonly represented at all depths and from all kind of substrata. To date, studies in spionid taxonomy have generally been confined to descriptions of new species and genera, without phylogenetic considerations (e.g. Hartman, 1941; Pettibone, 1962; Day, 1967; Foster, 1971; Light, 1978; Blake & Kudenov, 1978; Blake, 1983). Notable exceptions are publications by Mesnil (1896), Soderstrom (1920), Hannerz (1956) and Orrhage (1964); the first mentioned, even presented a tree depicting perceived intergeneric relationships. The three later workers placed additional emphasis on different organ systems and ontogenetic stages. Not un- expectedly, the consensus between all four is low. A study of relationships within any group relies on the assumption that the analysed taxa, in this case genera, constitute monophyletic, non-overlapping groups. In our view, this assumption is certainly, but to an unknown extent, violated in the Spionidae. Although the optimal procedure would have been to reduce these assumptions and use less inclusive groupings (e.g. species or populations), the number of described spionid species precluded this approach. Instead we have chosen to follow two lines of investigation. In the first, all known intrageneric variation was included in the cladistic analysis. The second was restricted to the type species of each genus and hence avoided the inclusion of non-monophyletic terminal taxa, reduced polymorphism, and considerably facilitated character coding. The present parsimony analyses represent the first explicit phylogenetic re- constructions of spionid relationships and aims to provide a preliminary tree topology for the family. This will help identify problem areas for future work on the Spionidae, and provide some outgroup indications for ongoing revisions of the Prionospio (Sigvaldadottir, unpublished data) and Atherospio (Mackie, unpublished data) com- plexes. M.4TERML AND METHODS Inpup tuxa The status of currently recognized spionid genera is open to debate. We have included all genera recognized by Blake & Kudenov (1978) plus most of those GENERIC INTERRELATIONSHIPS WITHIN SPIONIDAE 475 subsequently described. However, several (Polydorella Augener, 19 14; Apoprionospio Foster, 1969; Spwphanella Fauchald & Hancock, 1981; Neoboccardiella Buzhinskaja, 1985) were excluded for taxonomic reasons. In agreement with Blake & Kudenov (1978), Po&dorella is here considered a synonym of Pseudopolydora Czerniavsky, 188 1, and Apoprionospio a subgroup within Prionospio Malmgren, 1867, though these have respectively been treated as valid by Tzetlin & Britayev (1985) and Maciolek (1 985). Spiophanella is of doubtful status and requires further investigation, while Neoboccardia may well prove to be a synonym of Boccardia Carazzi, 1893. Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 For practical reasons relating to computer memory and long running times, the number of genera included in the analyses were further reduced by representing the Polydora-complex as a single taxon (i.e. Polydora BOSC,1802). The constituent genera (Amph$o&dora Blake, 1983; Boccardia, Boccardiella Blake & Kudenov, 1978; Carazziella Blake & Kudenov, 1978; Polydora; Pseudopolydora; Tripolydora Woodwick, 1964) are assumed to constitute a monophyletic group on basis of the specialised setae of segment five. Conversely, two supplementary taxa (Prionospio banyulensis Laubier, 1966, and Scolelepis (Paraxolelepis) Maciolek, 1987) of questionable taxonomic position or status (see Maciolek, 1985; Sikorski, 1994) were included. Prionospio banyulensis, together with li pilha Wilson, 1990, Wers markedly from other Pnonospio species in having branchiae from setiger three, not two. Scolelepis (Scolelepis) Blainville, 1828 and Scolelepis (Parascolel~is)are likewise separated as they differ in a number of features (e.g. palp morphology). Outgroup taxa The Poecilochaetidae Hannerz, 1956, Trochochaetidae Pettibone, 1963b and Uncispionidae Green, 1982 were selected for outgroup polarity determination. All are members of the Spionida, suborder Spioniformia (sensu Fauchald, 1977), and considered closely related but separate from the Spionidae (Dales, 1962; Orrhage, 1964; Green, 1982). Characters Character information was primarily derived from literature accounts and, in a number of cases, supplemented by information from examined specimens (including some type material). Emphasis was placed on original descriptions and redescriptions based upon type material or material from ‘near’ type localities. Thus features first described from ‘out of area’ material were not used due to doubts about the presence of these features in the type specimens. This conservative approach was taken to try and minimise errors, although it is recognized that some will undoubtedly be present. These can only be eliminated by the examination of all type material. The same characters (Table 1, and numerals below) and character states were used for both generic and type species analyses. 476 E. SIG\’.ILD,.\DOTTIR ETAL TABLE.1. Characters and character states Character Character states I Prostomiurn Pointed (0);Anteriorly incised (I); Anteriorly without incision (2). 2. Occipital antenna Present (0); Absent (I). 3. Caruncle Present (0); Absent (1). 4. Nurhal organ Long (0); Short (1). 3. Palps (basal scale) Smooth (0); Papillose (I); Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 Absent (2). 6. Eyes Present (0); Absent (I). 1. Dorsal branchiae Present (0); .4bsent (I). 8. Dorsal hranchiae Setiger 1 (0); Setiger 2 (I); (introduction) Setiger 3 (2); Setigrr 4 (3); Later setiger (4). 9. Dorsal hranchiae (end) Anterior (0);Median (I); Posterior (2). 10. Dorsal branchiae (interrupted) Present (0); Ahsent (I). 11. Dorsal branchiae (fusion with Present (0);.4hsent (I). notopodial larnel1aJ 12. Body region Distinct (0);Grade (1). 13. Dorsal crests Present (0);Absent (I). 14. Cephahc cage Present (0); Absent (I). 15. Notopodial hooks Present (0); Absent (I). 16. Modified notosetae (anterior) Present (0); Absent (I). 17. Modified notosetae (postrrior) Present (0); Absent (I). 18. Xeuropodial hooded hooks Present (0);Absent (1). 19. Neuropodial hooded hook One (0); Multiple blunt (1); (nurnher of secondar). treth) hfultiple sharp (2); Absent (3). 20. Neuropodial hooded hooks Upper (0); 1,ower (I). (position of secondar) tee&) 21. Anterior modified neurosetae Set 2 (0); Set 23(I); Absrnt (2). 22. Neurosetal spines Present (0); Absent (1). 23. Sabre setae Present (0);.4bsent (1). 24 .ha1 cirri or lobes One (0);Two (I); Three (2); Four (3); Five (4); Many (5); Absent (6). 25. .ha1 plate Present (0); .4bsent (1). (1j Prostomial shape is highly variable within the Spionidae. It varies from pointed as in Sco1elepi.s kudenovi Imajima, 1992 (Fig. 1A) to rounded in Microspio gracilis Blake, 1983 (Fig. 1B); from somewhat triangular in Prionospio steenstrupi Malmgren, 1867 (Fig. 1C) to T-shaped with conspicuous horns in Malacoceros tripartitus Blake & Kudenov, 1978 (Fig. ID); and from deeply incised in Microspio ganulata Blake & Kudenov, 1978 (Fig. 1E) to anteriorly entire in Xandams acanthodes Maciolek, 1981 b (Fig. 1F). Various intermediary shapes occur, making delineation of character states difficult, therefore we coded this in terms of three states only. (2) A number of spiotiids are provided with a short occipital antenna (or nuchal papilla). It is generally situated on the prostomial caruncle (Fig. lEj, occasionally arising (e.g. in Streblospzo Webster, 1879; see Dauer, 1994) just posterior to this. In some species of Aonides Claparede, 1864, Pobdora, Spiophanes Grube, 1860, and sevcral other genera (see Table 2), the antenna may be absent. (3) We have interpreted the spioniform caruncle as a posterior extension of the prostomium, sometimes surrounded by the nuchal organs. Hannerz (1 956), in his GENERIC INTERRELATIONSHIPS WITHIN SPIONIDAE 477 Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 Figure 1. Prostomial shape variation. A, Scolekpis kudenoui (redrawn from Imajima, 1992).B, Micmspio grm’lis (redrawn from Blake, 1983). C, Konospio stemtrupi Malmgren, 1867 (redrawn from Sigvaldadbttir & Mackie, 1993). D, Mulucocems tripartitus (redrawn from Blake & Kudenov, 1978). E, Micmspio grunulata (redrawn from Blake & Kudenov, 1978). F, Xandams amnthodes (redrawn from Maciolek, 1981h). studies of spionid larval development, referred to the caruncle as a ‘nuchal crest’. It can be absent as in Xandams (Fig. lF), or short as Prionospio (Fig. lB, C) and most of other genera. Laonice Malmgren, 1867, and Spiophanes kroyeri Grube, 1860 have sometimes been reported as having long caruncle, reaching back to the median part of the body (Blake & Kudenov, 1978; Blake 1983; Sikorski et al., 1988). Instead of constituting a caruncle, we believe the long prostomial extensions in these taxa represent nuchal organs. The caruncle is coded for presence or absence. (4) The nuchal organs are paired dorsal epidermal sensory structures (see Storch & Schlotzer-Schrehardt, 1988) that, in spionids, are usually positioned postero-lateral or posterior to the prostomium. Prionospio cristata Foster, 197 1 is unusual in having nuchal organs which unite across the caruncle. Poecilochaetus Claparede, 1875, Laonice and Spiophanes kroyen have long nuchal organs, extending back along the dorsum (see also character (2) ‘Caruncle’, above). Despite some detailed studies (e.g. So- derstrom, 1920, 1930; Rullier, 195 l ; Hannerz, 1956; Orrhage, 1964))information on spionid nuchal organs in descriptive accounts is poor, and the character is liable to display high degrees of homoplasy. From our own examinations of spionids we believe all to possess nuchal organs, however these may often be small and inconspicuous. Indeed, Rullier (1 95 1) and Rouse & Fauchald (1995) considered nuchal organs to be present in almost all polychaetes. We have assumed unreported nuchal organs to be present and have coded these as ‘short’. 178 E. SIGVALDAD~TTIRET 4. Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 B Figure 2. Spionidae palps. A, palp of RhYnch0J;pio gluku (Ehlers, 1897) lateral view (redrawn from Imajima, 1991a). B, smooth sheath of Scohhpis variegafa (redrawn from Imajima, 1992). C, papillate sheath of Scolelepis texunu Foster, 1971 (redrawn from Imajia, 1992). (5) AU spionids have paired palps; in most the palps are simple, each provided with a ciliated groove (Fig. 2A); a few species lack the groove (Dauer, 1983, 1987). Palp ciliation patterns are of potential use in characterizing genera (Dauer, 1987), however information is currently limited to small number of species (Dauer, 1994). Some spionid palps additionally possess a basal sheath (or scale) on the palps. When present, this may be smooth, as in Scolelepis variegata Imajima, 1992 (Fig. ZB), or papillose, as in ScolelepzS (Parascolelepis) texana Foster, 197 1 (Fig. 2C). (6) Eyes are subdermal and highly variable in number and development, both within and between genera (Fig. 3A-C). The character is coded as present or absent. Observations can be complicated due to the fact that, in some specimens, eyespot pigments may fade and disappear after long periods of preservation in alcohol. (7) We employ the term ‘dorsal branchiae’ for the usual spionid branchiae that arise dorsally from the base of the notopodia (Fig. 4A, B), and occur in all genera except Spiophanes. It does not include the accessory branchiae that arise from the posterior part of the notopodium in most species of &pi0 Hartman, 1951 (except D. branchychuta Blake, 1983), some species of Scolelef~is(e.g. S. pettiboneae Maciolek, 1987), or the similarly positioned branchiae in the Poecilochaetidae (see Mackie, 1990). Some species of Lindaspio Blake & Maciolek, 1992, are unusual in additionally possessing ventral branchiae. These different kinds of branchiae are considered as non-homologous and constitute autapomorphies at the analysed level. (8) Most spionid genera have branchiae commencing on either setiger one or two. The only exceptions are Aurospzo Maciolek, 1981a, Athospio (Mackie & Duff, 1986), Xandams, some members of the Pobdora-complex (Amphipohdora, Cararriella, Pobdora and Pseudopo&dora), female specimens of Qgospio Claparkde, 1863, and Prionospio banyulensis and P pilkena. GENERIC INTERRELATIONSHIPS WITHIN SPIONIDAE 479 Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 Figure 3. Prostomial eyes. A, Scolelepir l&lutu with three pairs of eyes (redrawn from Imajima, 1992). B, Pnonospio banyulensis Laubier, 1966, with two pair of eyes (redrawn from Sigvaldadottir, 1992). C, Puruprionospio coom with one pair of eyes (redrawn from Wilson, 1990). “A B Figure 4. Spionidae branchiae. A, short branchiae of Scohhfiispettiboneae dorsal view (redrawn from Maciolek, 1987). B, long cirriform branchiae of Aionospio delta Hartman, 1965 lateral view (redrawn from Maciolek, 1985). (9) In contrast to the commencement of the branchiae, which appears constant, there is often considerable intrageneric variation in their actual number, especially for taxa with many branchiae, were also size-related differences may constitute a problem. The character is coded according to three states: ‘anterior’ when the branchiae do not occur beyond about setiger 15, ‘median’ when they are present to around setiger 20-50 but absent from the posterior setigers, and ‘posterior’when they occur on almost all posterior segments. 480 E. SIGVALDADOTI'IR ElAL Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 Figure 5. Branchial fusion with notopodiai lamellae. A, basal fusion in hfararelleriajonesi, (redrawn from Maciolek, 1984). B. almost complete fusion in Scolelepis carunculata (redrawn from Blake & Kudenov, 1978). (10) Male Bgospio, Qgospi0psi.sBlake, 1983, and some members of the Pobdora-complex (Boccardia and Boccardiella) have an interrupted branchial distribution; branchiae being absent from several anterior setigers following their introduction. (1 1) Spionid branchiae are either free from, or fused with (Fig. 5A, B), the notopodial lamellae. No distinction has been made between completely or partly fused, or concerning which region of the body the fusion occurs. (12) Most spionids do not have well-defined body regions (Fig. 6A), the parapodia generally changing gradually along the body. The parapodia of Sjiophanes kroyeri, however, differ such that anterior, median and posterior regions can readily be discerned. The Trochochaetidae (see Pettibone, 1976; Mackie, 199O), Poe- cilochaetidae (see Read, 1986; Imajima, 1989; Mackie, 1990) and Uncispionidae (Fig. 6B) have distinct body regions. (13) Dorsal crests are considered present when the postsetal notopodial lamellae connect completely over the dorsum, forming ridges or crests. Crests may be restricted to a single setiger (e.g. in Prionospiofallav Soderstrom, 1920), or occur on a number of setigers as evident in I? cirnzi-ra WirCn, 1883 (Fig. 74. They can be high and conspicuous, low and comparatively inconspicous, or a combination of both (Fig. 7B). Due to high degrees of intrageneric variation and inconsistent literature descriptions we have coded this feature simply as absent or present. (14) A cephalic cage, formed by the long capillary setae of the anteriormost setal bundles, is present in trochochaetids, poecilochaetids and uncinispionids. It is never well-developed in spionids. Some species of Marenzelleria Mesnil, 1896 do have some slightly longer anterior notosetae (Maciolek, 1984), but they are relatively few among the many notosetae present and are not considered homologous to the outgroup state. (15) Spionid hooded notopodial hooks typically terminate in a large main tooth, usually supplemented by at least one smaller secondary tooth. Some species (e.g. Lindarpio dzbranchia Blake & Maciolek, 1992) have unidentate notopodial hooks. Under light microscopy the distal regions of the hooks are seen to be surrounded by a transparent hood; sometimes a small secondary inner hood can also be discerned (Fig. IOC). GENERIC INTERRELATIONSHIPS WITHIN SPIONIDAE 48 1 Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 Figure 6. A, Prionospiofallax Soderstrom, 1920, lateral view. B, Uncispzo harhnanae, lateral view (redrawn from Green 1982). (16) Modified anterior notosetae are present in the Pobdora-complex (Fig. 8) and Lindmpio. Micmspio paradoxa Blake, 1983, unique in the genus with its modified notosetae on setigers four and five, was therefore scored as polymorphic in the generic analysis. (1 7) A large range of different modified posterior notosetae is present in a several taxa under consideration: e.g. the short aciculae-like setae of Pobdora tentuculata Blake 482 E. SIGVALDADOTTIR ETAL. Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 Figure 7. Dorsal crests. A, Pnonospw cirnyiro WirCn, 1883, showing low crests on setiger 11-13 (redrawn from Foster, 1971). B, Prionospzo cnikzta, with high crests on setigers 7 and 9, and low one on setiger 8 (redrawn from Foster, 1971). Fispre 8. h4odified notosetae of setiger 5 on PoQdora comuta Bosc, 1802 (redrawn from Blake & Maciolek, 1987). & Kudenov, 1978 (Fig. 9A), the enlarged curved setae (Fig. 9B) of Spiophanes bombyx (Claparede, 1870), and the slender spines of Poecilochaetus spinulosus Mackie, 1990 (Fig. 9C). For the Trochochaetidae (Fig. 9D) there is the added autapomorphic feature of complete retractability (Weitbrecht, 1984). The modified notosetae are coded simply as present or absent. GENERIC INTERRELATIONSHIPS WITHIN SPIONIDAE 483 Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 Figure 9. Modified notosetae (posterior). A, acicula-like seta of Po$dora tmtanrlata (redrawn from Blake & Kudenov, 1978). B, enlarged curved setae of Spiophanes bombyx Claparhde, 1870 (redrawn from Imajima, 1991b). C, slender spines of Poecilochaetus spinulosus (redrawn from Mac!&, 1990). D, notosetae from posterior abdominal region of Tmchochueta carica (redrawn from Pettibone, 1976). (18) The neuropodial hooded hooks are generally similar in structure to those of the notopodia (see above), though, within individual species (e.g. Lindaspio dibranchia), they may be furnished with more secondary teeth. Neuropodial hooks are present in uncispionids and almost all spionids. Scolecolepides 3eemani Mitchell & Edwards, 1988 is unique in lacking both notopodial and neuropodial hooks. (19) Genera possessing neuropodial hooks with single secondary tooth include those of the Polydora-complex (except Tripolydora), Australospio Blake & Kudenov, 1978, Sygospio, Xandaros, Athemspio, Pseudathmspio Lovell, 1994, SygospiopszS and the outgroup Uncispionidae (Fig. 10A,B). It occurs in a polymorphic condition in 12 other taxa; mainly with multiple blunt teeth (Fig. 10D). Multiple sharp teeth (Fig. 1OC) are predominant in the Prionospio-complex (Aurospio, Laubieriellus Maciolek, 1981 b, Orthoprionospio Blake & Kudenov, 1978, Prionospio, Paraprionospio Caullery, 19 14 and Streblospio), Scolelepis (Parascolelepis) and Lindaspio. (20) Atherospio, Pseudathemspio and @gospiopsh are the only spionid genera with a secondary tooth situated under the main fang (Fig. 1OA). (21) Anterior modified neurosetae covers the moditied hook-like setae of setiger 1 in Spiophanes (Fig. 1lA), the curved spines of setiger 2 and 3 or setiger 2 to 4 in the Poecilochaetidae (Fig. 11B), and those of setiger 2 and 3 in the Trochochaetidae (Fig. 11C). (22) Short neurosetal spines (simple, aristate, geniculate), are present in the Tro- chochaetidae (Fig. 12A), Poecilochaetidae (Fig. 12B), Lindaspio (Fig. 12C), Athmspio (Fig. 12D), Australospio (Fig. 12E), Xandaros (Fig. 12F) and Pseudathemspio (Fig. 12G). E. SIGVALDADOTTIR ET AL. Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 B~ C Figure 10. .kangement of secondai?; treth of hooded hooks. A, Ah@ distichs (redrawn fiom Mackie and Duff, 1986). B, Po$dora comula (redrawn from Blake & Maciolek, 1987). C, phonospio SQ&Q (redrawn from Mackie & Hartley. 1990). D, Aonidellu dayi Maciolek Blake, 1983 in Lrjpezjamar, 1989 (redrawn from Maciolek Blake, 1983). Fi-gu1-e 11. Modified neurosetar (anterior). A, crook-like setae of setiger one in Spiophanej kryeri (redrawn from Imajima, 199lbi. B, cunvd neuropodial spine from setiger 2 from Poecilochaetus spinulosus (redrawn from Mackie, 19901. C, neurosetae from setiger 2 of Tmchochueta diwrapoda (Hoagland, 1920) (redrawn from Pettibone, 1976). (23) A small number of special heavily recurved setae are situated in the ventralmost position of the neurosetal bundle in many spionids. They are often sheathed and punctate in appearance (Fig. 12H). (24) The anal appendages (cirri or lobes) vary in their form and number (Fig. 13A--EJ,making state delineation difficult. Information is furthermore often lacking since many spionid descriptions are based on specimens lacking their posterior ends. Nevertheless, we believe scoring the anal appendages is potentionally of value as a phylogenetic character and included it to explore this possibility. The character is polymorphic in the Pobdora-complex. (23)The pygidia of Scolelepis (Fig. 13G) and DzspZo possess a small, ventrally situated, oval cushion-like anal plate. We consider this to be different from the more funnel- like structures that occur in the Pohdora-complex. I B D E F Figure 12. Short neurosetal spines. A, Tichochaetu diverupoda (Hoagland, 1920), aristate neurosetae from median setiger (redrawn from Mackie, 1990). B, Poecilochuetm hyshicosus, aristate seta (redrawn from Mackie, 1990). C, Linduipio dibranchiata, unworn and worn modified spines (redrawn1 from Blake & Maciolek, 1992). D, Athaospio distichs, aristate spine from setiger 5 (redrawn from Mackie & Duff, 1986). E, Australospio t@a, neurosetae from setiger 7 (redrawn from Blake & Kudenov, 1978). F, Xunuizis acanthodes, recurved and straight neuropodial spines from setiger 10 and 14 (redrawn from Maciolek, 1981b). G, Pseuduthem5piofuuchaldi, fringed seta from setiger 5 (redrawn from Lovell, 1994). H, sabre seta of Orthoprionospw cirnznia (redrawn from Blake & Kudenov, 1978). Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 October 08 on guest by https://academic.oup.com/zoolinnean/article/119/4/473/2633681 from Downloaded 486 E. SIGVALDADOTTIRET AL A )-5J C Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 D Figure 13. Pygidid structures of Spionidae. A, Streblospw benedicti Webster, 1879 (redrawn from Foster, 1971). B, Aionospw bmyuhis Laubier, 1966 (redrawn from Sigvaldadottir, 1992). C, Xandams acmthodes (redrawn from Maciolek, 1981b). D, odz$mm~osp;O cin$mnin (redrawn from Blake & Kudenov, 1978). E, PoeEilochnetus hilobatur (redrawn from Imajima, i 989). F, Ahspio dirticha (redrawn from Macke & Duff, 1986). G, Scoleleplsfoliosa (Audouin and Milne Edwards, 1833) (redrawn from Maciolek, 1987). Parsimony anabses Due to extensive running time and computer memory insufficiency, the six most polymorphic genera (Microspi0 Mesnil, 1896, Prionospio, Scolelepis (Scolelepis), Spiophanes, fjgospio and Pobdora) were excluded from the generic analysis. The first completed analysis therefore included 25 taxa with 25 characters and 64 character states (Table 2). The type species analyses included 31 taxa with 25 characters and 63 character states (Table 3). Character matrices for the generic and type species analysis are provided in Tables 2 and 3, respectively. Both unknown and non-applicable character states were scored as questionmarks. Data matrices were edited in MacClade, version 3.01 (Maddison & Maddison, 1992), analysed with PAUP, version 3.1.1 (Swofford, 1993), and resulting trees and character state transformations examined in MacClade. All searches were carried out on a Macintosh Quadra 700 provided with math coprocessor, with the following PAUP settings: heuristic search algorithm, TBR branch swapping, random addition sequence (25 repetitions for the generic and 100 for the type species analysis), collapse zero length branches, save all minimal trees, character optimisation by ACCTRAN (accelerated transformation), and multistate taxa counted as un- certainties. All multistate characters were unordered and all characters initially of equal weight. We applied successive weighting (Farris, 1969; Carpenter, 1988) in order to reduce the impact of characters exhibiting low congruence with other characters on the primary trees, and thereby increase the signal/noice ratio in the analysis. The successive weights are based on maximum values of retention indices. GENERIC INTERRELATIONSHIPS WITHIN SPIONIDAE 48 7 Branch support (Bremer, 1988, 1994) was calculated in order to assess stability of individual branches in near-most-parsimonious trees. Both successive weight and branch support search settings were similar as described above for the type species analysis. RESULTS AND DISCUSSION Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 Generic analysis The generic analysis yielded 13 305 equally parsimonious trees with 68 steps, a consistency index (excluding uninformative characters) of 0.48, and a retention index of 0.67. This number of trees and the completely collapsed consensus tree (not shown) do not facilitate any insight into higher interrelationshipswithin the Spionidae. These results highlight several problems in polychaete phylogeny. First, it is difficult to extract comparable and consistent information from a literature which abounds with incomplete, ambiguous and erroneous descriptions. Second, as hy- pothesized in the introduction, the assumption that the terminal spionid taxa are monophyletic and non-overlapping may be incorrect. New taxa are often still introduced based on differences rather than derived similarities, thus yielding non- monophyletic assemblages. Inclusion of such groups in the analysis increases the level of polymorphism present, and this decreases the possibility of obtaining unambiguous results. Consequently, any future comprehensive phylogenetic estimates of the group will have to be based on re-examined specimens, instead of interpreting descriptions obtained from the literature, probably reducing a priori assumptions of monophyly by correcting misunderstandings and errors in earlier descriptions. In the following section, we are considering only the results of the type species analyses. 3pe species anaLysis The analysis yielded four equally parsimonious trees (Fig. 14A-D) with 89 steps, a consistency index (excluding uninformative characters) of 0.43 and a retention index of 0.65. There is some variation between the four primary cladograms, however two main patterns (each comprising two trees) are in evidence (Fig. 14A & C and B & D). Within each pattern the topologies differ only in the relationships between Australospio-Marenzelleria, Spio Fabricius, 1785 and Dispio. In two trees (Fig. 14C, D) Spio and &pi0 form a polytomy with the Australospw-Maren~elleria clade, whereas in the other two (Fig. 14A, B) Spio is sister to Australospio-Maren~eeIleria, and Dispw likewise to Australospio-Spio. The differences between the main patterns themselves are primarily due to changes in the relationships of four species: Laonice cirrata (Sars, 1850), Spiophanes kmyeri, Aonides oxycephala Sars, 1862, and Uncispio hartmanae Green, 1982. In pattern 1 (Fig. 14A, C), Laonice-Spiophanes is the sister group to AurospioStreblospio (the Prionospw-complex), with Aonides the sister to these both together, and Uncispio sister to all Spionidae smu lato. In pattern 2 (Fig. 14B, D), Uncispio is sister to Aonidella- E. SIGV.XDAD~TTIR ETAL. Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 5 z 0 c 0 - 3 0 3 0 0 0 0 c 0 0 0 0 0 0 - 0 -0 m. c 0000 M 4 --000~000~00000C0000000000 NZOO Bi ZZ~--*Ncc---cc-oc*N-c---c-- 0Zcm --003c00~000c00000c00c00004 0-00 ------He - -- ~$!-$!00$!0~~--00c0cc0c-c-c0c444 4444 4 44 -0--00003000000-3000000000 000-- -00-4 GENERIC INTERRELATIONSHIPS WITHIN SPIONIDAE 489 Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 mecilochaetus swrpens Trochochaeta m~lCis4tosa UnCiSpiO hutmanre Aonides owephala Aurospi o dibranchia ta OrthOpfirmoSpiO cirrifonnia Paraprionorpio pirulata 'I PriOnOSpiO lMnyUlsnSiS PZfMOSpiO SteEMtNpi Laubi eri el 1us grasslei Streblospio bnedicti monice iirrata L Laonice cirrata mi ophanes kroyeri 1 soionhanes kroveri AwItralOspio trifida AWt>alOSpio tiifid. SCOleCOl~pid~Smi SCOleCOlepideS banhami mlacoceros vulgaris llalacoceros vulgaris Mranaelleria wireni Poecilocheetus sewam Marsnnrelleria wireni mi0 filicornis Trochochaets mltisetosa DiSpiO uncinata DisRio uncinata UnCiSpiO hartmnae sgio filicornis Wicrospio msscmikowianus Aonidella cirrobranchiata nicrospio mscmikowianus moapio eleguu Xandaros acanthodes Imospio deguu Scolelepis fS.1 swamta Aonides oxycephala scotelepis 1s.) swauuta SCOhIepiS fP.1 cridrntata Atherospio disticha Scolelepis 1P.I tridentaca Linddspio dibranchiaca Pseudatherospio feuchaldi Lindaspio dibranchiata Polydora cornuta PVpOSpiORSiS dUbh Polydora cornuta RhynchOSDio alutaea AurOSpiO dibranchiata RhpChOSpiO QlUtaea A&eros~o dhichs OrthopriMospio cirrifonnia €!%Atherospio diaticha PswUdatherospiO fauchaldi Paraprionospio pinnata 0 Psaudathmoapio fauchaldi D mospiopsis dubia PZfMOSpiO banYU1EIlSfS PyQOSpioWiS dubia PriMOSpiO StMllStNRi Laubieriell ua grasslei StreblOSpiO benedicti AUStZdlOSPiO trifida Scolecolepides banhami Wlacoceros vulgaris mecilochnetus serm Wrenzelleria wireni hochOchaet6 multisetoaa DiSpiO vncinata Uncispio hartmnnae Spio filicornis Aonidella Cirrobranchiata Nicrospio mescmikowianus Xandaros acanthodes Pygospio elegans AtherOSpio disticha Scolelepis fS.1 sauam¶ta Pxeuddtherospio fauchaldi scolslepis fP.1 tridentata mosnionsis dubia Lindaspio dibranchiata A&Vil&piO trifida Polydora cornuta Scolecolepides be- RhpChOSpiO UlUtaea llalacoceros vulgaris Laonice cirrata llarenzelleria wireni SpiOphPneS kroyeri spio filicornis Dispio vncinata Wicrospio mescznikowianus m pypospio elwan8 SCOlelepiS IS. I swmmta SCdd~pis1P.I tridentata Scolelepis fP.1 tridentata LindaSpiO dibranchista Lindaspio dibranchiata Polydora comuta Polydora cornuta Rhpchospio glutaea Rhpchospio ulutsea Aonides 0-ephala r!5Aonides oxycephala - Aurospio dibranchiata Aurospio dibranchiata OrthopriMospiO cirri formia Orthoprionospio cirrifonnia Paraprionospio pi-ta Paraprionospio pi- ta Prionospio bnnyUlensis PriMOspiO banyulensis c Prionospio steenstrupi Prionospio SteenStNpi II Laubieri el 1us grass1 ei Laubieriellus grasslei streblospio benedicti 1 Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 October 08 on guest by https://academic.oup.com/zoolinnean/article/119/4/473/2633681 from Downloaded GENERIC INTERRELATIONSHIPS WITHIN SPIONIDAE 49 1 Xandaros and together these now form a sister group to Atherospio-prSospiopsis, Aonides is sister to Uncispio-Rhynchospio, while Laonice is sister to UncispioStreblospio, with Spiophanes then sister to Uncispio-Laonice. The consensus tree derived from the four trees is only partially collapsed (Fig. 14E), highlighting the variable relationships of Uncispio, Aonides, Laonice, Spiophanes, Spio and fipio, as well as the stability of the Aonidella-Xandams, Atherospio-Ogospiopsis, Aurospio-Streblospio, Australospio-Marenzelleria, Scolelepis (Scoleltpis)-Scolelepis(Parmcolelepis) and Pobdora-Lindaspio clades. Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 It is interesting that two of the primary trees (Fig. 14B, D), as well as the consensus tree (Fig. 14E), did not support a monophyletic Spionidae as currently delineated, but also included Uncispio and Uncispionidae within the group. The position of the uncispionids clearly merits further evaluation. Weighted gpe species anaGysis Successive weighting yielded two trees, both of which were also among the four initial ones (Fig. 14A, C). The two trees differ only in the relationships of Spio and &pi0 within the AustralospioSpio clade (see above). Since this difference does not affect the four main clades in the trees, we have arbitrarily selected the first tree for further discussion (Figs 14A, 15). Four main groups emerge from the cladogram (Fig. 15): Clade 1: Aonidella and Xandaros. Clade 2: the Prionospio-complex, Aonides, Laonice and Spiophes. Clade 3: Australospio, Scolecolepides, Malacocms, Marenzelhia, Spio, O;rpio, Microspio, FJgospio, Scolelepis (Scolelepis),Scolelepis (Parascolel$is), Lindaspio, Pobdora and Rhynchospio. Clade 4: Athtrospio, Pseudathospio and FJgospiopszS. Clade 1. In her description of the genus Aonidella, Maciolek Blake (1983) considered it most closely related to Aonides. Our cladogram (Fig. 15) does not support this and instead indicates a sister relationship with Xandams. However, the evidence is weak as the single character absence of occipital antenna (2) exhibits a high degree of homoplasy. Clade 2. The Prionospio-complex is the major group within this clade. Prionospio has been variously subdivided into a number of genera or subgenera (Foster, 1971; Blake & Kudenov, 1978; Maciolek, 1985)) and some other genera (e.g. Streblospio; Orthoprionospio; Aurospio; Laubieriellus) have been considered closely related. The main diagnostic characters of Prionospio are branchiae from setiger two, branchiae limited to anterior setigers, and three anal cirri. Laubieriellus differs from Prionospio in lacking notopodial hooded hooks (Maciolek, 1981 b). Aurospio was separated from Prionospio on the basis of branchiae from setiger three, form of branchiae, and their fusion with the notopodial lamellae (Maciolek, 1981 a). PartgriOnospw has branchiae from setiger one, platelike pinnules on the branchiae, and a-prominent ridge across setiger one. Orthoprionospio also has branchiae from setiger one, but differs in having cirriform branchiae and no ridge across dorsum of setiger one (Blake & Kudenov, 1978). NP r Poecilochaetus serpens zg m - Uncispio hartmanae b ul N Aonidella cirrobranchiata Xandaros acanthodes 0 A- Aonides oxycephala Aurospio dibranchiata Orthoprionospio cirriformia Paraprionospio pinnat a xz Prionospio banyulensis NP! Prionospio steenstrupi Laubieriellus grasslei Streblospio benedicti Laonice cirrata Spiophanes kroyeri Australospi 0 trifida Scolecolepides benhami 0 Malacoceros vulgaris Marenzelleria wireni Spio filicornis Dispio uncinata Microspio mescznikowianus Pygospio elegans Scolelepis (S.) squamata Scolelepis (P.) tridentata _I Lindaspio dibranchiata &A Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 I Rhynchospio qlutaea mm M- M- dtherospio disticha I -23...- Pseudatherospi o faucha 1 di yz' - Pygospiopsis dubia b 1 GENERIC INTERRELATIONSHIPS WITHIN SPIONIDAE 493 Streblospio has branchiae from setiger one, only one pair cirriform branchiae, and a prominent hood or collar across dorsum of setiger two. The synapomorphies multiple sharp secondary teeth on the ventral hooded hooks (19) and two anal cirri (24), the latter character further modified within the group, support the close relationships between this group of genera (Fig. 15). Streblospio is the most plesiomorphic genus within the Prionospio-complex. Laubieriellus shares the lack of occipital antenna (2) and presence of three anal cirri (24) with the rest of the group. Prionospio shares the presence of notopodial hooks (15) with the Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 Aurospio-Prionospio banyuhnnsis clade. Prionospio baydensis has been questionably referred (Maciolek, 1985) to Aurospio, but cannot be referred to either genus. Rather it is sister to the Aurospio- Paraprionospio-Orthoprionospio clade. The position of ? banyulensis will be dealt with in the future (Sigvaldadottir, unpublished data). Paraprionospio and Orthoprionospio form a sistergroup, having dorsal branchiae from setiger one (8), and reduction of number of anal cirri from three to one (24). Aurospio constitute the sister to these two taxa as evidenced by absence of dorsal crests (13). The Laonice-Spiophanes group is supported by long nuchal organs (4) and branchiae reaching to the median part of the body (9), the latter character becoming non- applicable in Spiophanes with the loss of branchiae (7). The two taxa constitute the sister group to the Prionospio-complex, as evidenced by the presence of dorsal crests (13). Aonides, in turn, forms the sister group to the Prionospio-complex plus Luonice- Spiophanes, based on presence of sabre setae (23). Clade 3 is supported by absence of occipital antennae (2) and branchiae reaching to the posterior end (9), both characters, however, exhibit homoplasy (Fig. 15). Rhynchospio Hartman, 1936 is the most plesiomorphic genus, forming a sister group to all the other genera. This genus has been considered closely related to Malacoceros Quatre- fages, 1843, being treated either as a valid genus (Hartman, 1959; Day, 1967; Fauchald, 1977; Imajima, 1991 a) or as a subgenus within Malacoceros (Foster, 197 1; Pettibone, 1963a). Rhynchospio and Malacoceros are well separated in the cladogram, Malacoceros and Marenzelleria forming a sister group to Scolecolepides and Australospio, the latter united by the presence of neuropodial spines (22).Spio is sister to the Australospio-Marenselleria clade and Microspio, often regarded as being close to Spio (e.g. Hannerz, 1956; Blake & Kudenov 1978; Maciolek, 1990) is sister to Australospio-Dispio. Blake & Maciolek (1992) regarded Scolecolepides and Lindmpio as related genera and Blake & Kudenov (1978) considered Australospio closely related to Scolelepis, Aonides and Dispio. Instead, in our cladogram, Lindmpio and Pohdora appear as sister taxa, based on presence of modified notosetae (16). Blake (1979) had earlier put forward the hypothesis that the Pobdora-complex had perhaps evolved from a Microspio-type ancestor. The contrast between the relationships in clade 3 and most of those proposed in the literature is marked. The only uncontradicted relationship is that between the two ScoleZepzS subgenera (Hannerz, 1956; Orrhage, 1964; Maciolek, 1987). The clade constitutes a somewhat morphologically heterogenous assemblage, and the group lacks strong support in our analysis, being based solely on three homoplasious characters. The topology within the clade is weak, and therefore changes are to be expected in future analyses. 494 E. SIGVMDADO'ITIR ETAL. Tmis 4. Taxon names used by earlier authors and their current status Current name Mesnil ( 1896) Sodentrom (1 920) Hannerz (1 956) Orrhage (1 964) Scolelepu (Scolelepu) Jmne, Nm,,vmnzdes Nmne, Nm'nides, Nm'ne, Nmnides, (except .vmldes (except Nmnides Nm'nzdes tridentata) hidentata) Scolekpu (Pararcolelepu) - - hinides tridmtata Nm'nides hidmtata Malacocms scolelepu Scolecoleps, Colobranchus scol.lep;l scolelepir haze Spwnides Loonzce Laonice Laonice Tmchochae - Dlsorninae (in part) Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 Trochochaetidae - - Disomidae Duomidm Clade 4. The group Athmspio-Pseudathmspio-Qgospiopsis is supported by three syn- apomorphies: secondary tooth below main fang on hooded hooks (20); bilobed prostomium (1); and fusion of branchiae with notopodial lamellae (1 1). The first synapomorphy is nonhomoplastic, whereas the two other states also appear in other parts of the cladogram (Fig. 15). The close relationship between Atherospio and @gospiopsZr was anticipated by Mackie & Duff (1986). Lovell (1994) later introduced Pseudatherospio and considered the three genera to be more closely related to each other than to any other spionids. This is supported by our tree topology. Further, dtherospio and Pseudathspio constitute sister taxa, as evidenced by presence of short neurosetal spines (22). Branchiae from setiger 1 (8) are reduced in Atherospio, and only appear as a synapomorphy under the ACCTRAN optimization used. The monophyly of the Atherospio-Qgospwpsis clade is well-corroborated, and subfamily status would seem justifiable for the group. However, consideration of the unstabilities in other parts of the tree and their possible effects on this clade, as well as the preliminary nature of this study, cautions us against naming it at present. The matter will be considered in more detail following the description of additional taxa (Mackie, unpublished data). As with the generic analysis, the type species analysis suffers from an insufficient number of characters to obtain stability in the phylogenetic reconstruction, and too many of the terminal taxa rely on available descriptions from the literature. Calculation of branch support (Bremer, 1988, 1994) from the unweighted data set provided the discouraging result of a fully collapsed consensus tree already at one additional step, denoting that no clades are unequivocally supported in trees one single step longer than the most parsimonious ones. Nevertheless, one advantage over the generic analysis is the avoidance of problems due to para- or polyphyletic terminal taxa. This increases the resolution of the analysis but, of course, only includes a selection of all known spionids. .Hktorical compalzrons In order to compare our results with the earlier views of Mesnil(l896), Soderstrom (1920), Hannerz (1956), and Orrhage (1964), we have transformed their classifications into cladograms. To avoid nomenclatural confusion the generic names they used have been updated to conform with current usage (Table 4). hlesnil (1896) examined the relationships between the genera and summarised GENERIC INTERRELATIONSHIPS WITHIN SPIONIDAE 495 Prionospio Aonides Aonides Group 1 Prionospio Clade 1 Laonice Laonice spio nalacoceros ni craspio 1 - Maarenaell eri 2 a Pygospi 0 Group spi 0 Polydora 1 nicrospio Clade 2 Scolel epis 1S.I -J Group 3 Pygospio I Malacoceros - - Scolelepis fs. ‘LMarenzelleria A B Polydora Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 Malacoceros Aonides AOni des Nerininae Prionospio Clade 1 Scolelepis 1s.) Laonice Prlonospio Spiophanes taoni ce Laonicinae nala coceros Spi ophanes spio spzo Microspio Clade 2 Mi craspi 0 Pygospi 0 spioninae Pygospf 0 Scolelepi s 1s. C Polydora D Polydora Aonides Aonides Prionospi o Clade 1 Laoni ce Laoni ce Group 1 Spiophanes Scolelepi s (s.) Scolelepis (P.) Ma1 a coceros Group 2 Inlcrospio Pygospio Clade 2 Microspio scolelepis (s.I GrOUp 3 Pygospio scolelepis 1P.I Polydora Polydora E F Prionospio IPrionospio Laonice Laonicinae 1 I Laonf ce Clade 1 Spiophanes I 1 spi ophanes 1 Malacoceros 1 spi 0 Pygospio Glade 2 scolelepis 1s.) scolelepis (P.) Polydora H Figure 16. A comparison between the present analysis and earlier classifications. Genera now referred to other families are excluded from the trees. A, Mesnil’s classification (Boccurdiuis included in Po4doru for ease of comparison), B, our classification with Mesnil’s taxa. C, Soderstrom’s taxa. D, our classification with Soderstrom’s taxa. E, Hannerz’s classification. F, our classification with Hannerz’s taxa. G, Orrhage’s classification. H, our classification with Orrhage’s taxa. these in an actual tree (redrawn as a conventional cladogram in Fig. 16A). He divided the spionids into four groups based on certain external morphological features; primarily those relating to the prostomium, branchiae, parapodial postsetal 496 E. SIGYALDADOTTIRETAL. lamellae, hooded hooks and anal cirri. Our corresponding tree topology, using the same taxa and a similar methodology (Fig. 16B), also included the Laonice- Aonzdes-Przonospw and itlalacoceros-i~ar~~elleriagroups, but otherwise had little in common. Soderstrom ( 1920) additionally incorporated reproductive and anatomical char- acters in his classification (translated into a cladogram in Fig. 16C). He divided the family into two (unnamed) groups. The first was subdivided into three subfamilies: Nerininae, Laonicinae and Disominae. The last mentioned ( = Disomidae Mesnil, 1897) included &ornu ( = Trochochaeta) and Poecitochaetus which, at the present time, Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 are respectively assicgned to the Trochochaetidae and the Poecilochaetidae. The second group consisted of the subfamily Spioninae. There was little consensus with Mesnil(l896) and both workers were highly critical of the other’s work (Soderstrom, 1920; Mesnil, 1925). The only agreement between Soderstrom’s tree and ours (Fig. 1 6D) was the Prionospio-Laonice-S’iophanes grouping. Hannerz (1956) studied the larval development of spionids, trochochaetids and poecilochaetids, and produced his classification using evidence from egg type, development (pelagic or protected) and larval morphology. He did not accept Soderstrom’s separation of the Nerininae and Laonicinae (Fig. 16E), distinguishing iblalacocems as a separate group, though the Spioninae was retained. Concordance with our tree (Fig. 16F) was again poor. Orrhage (1 964), using morphological and anatomical features of adult spionids, trochochaetids and poecilochaetids, followed Soderstrom and Hannerz in recognizing the Spioninae, with Spio as the most primitive member (Fig. 16G). Soderstrom’s Laonicinae (Fig. 16C) was also accepted but, in agreement with Hannerz (Fig. 16E), Mahcoceros was once more separated from the other genera. Thus, with the exception of considering ScolelepzS to belong to a separate subfamily (an action proposed earlier by Mesnil, see Fig. 16A), Orrhage’s classification resembles that of Hannerz. However, the relationships between the four recognized subfamilies was unstated (Fig. 16G). Our classification (Fig. 16H) differed most significantly in the relative positions of Pobdora and i2lulacoceros. Conclusion Although, as above, it is possible to transform earlier classifications into cladograms, it should be kept in mind that these studies were not carried out within a cladistic framework. The lack of consensus between tree topologies we refer to the subjective treatment of relatively few selected characters, which differed considerably between studies. Our own analysis presents the first explicit testable hypothesis of the interrelationships within the Spionidae and, as such, represents a major development from previous studies. Nevertheless, we acknowledge the shortcomings in the use of literature descriptions restricted to certain ‘traditional’ morphological features that are often inadequately reported. There is a clear need for more detailed and comprehensive information concerning spionid polychaetes. It is our hope that the present study will stimulate the acquisition of such data and form a basis for future studies on spionid phylogeny. GENERIC INTERRELATIONSHIPS WITHIN SPIONIDAE 497 ACKNOWLEDGEMENTS Thanks to Sven Bostrom for working facilities at the Zoo-tax section of the Swedish Museum of Natural History (ES), and Andrew Sikorski for Russian-English translations. Financial support was obtained from Hierta-Retzius fund (ES), the Swedish Natural Science Research Council (contract no. 9555-316, FP), and the Swedish Institute and Marathon Oil U.K., Ltd. (ASYM). Downloaded from https://academic.oup.com/zoolinnean/article/119/4/473/2633681 by guest on 08 October 2021 REFERENCES Augener H. 1914. Polychaeta 11. Sedentaria. Fauna Sud~es~-Aus~al~s5: 1-170, 1 pl. AudouinJV, Milne-Edwards H. 1833. Classification des anntlides et description de celles qui habitent les c6tes de la France. Annales des Sciences Naturelles, Park 30: 41 1425. Blainville D. de 1828. Vers a sang rouge. Dictionnaire des Sciences Naturelles, Par& 57: 368-501. Blake JA. 1979. 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