^^/ Iiiveitebialc Biology 122(2): I 14-125. ? 2003 American Microscopical Society. Inc. Phylogeny of the Cocculinoidea (Mollusca, Gastropoda) Ellen E. Strong,'??' M.G. Harasewych,^ and Gerhard Haszprunar^ 'Bell Museum of Natural History, Department of Fisheries, Wiidlile and Conservation Biology, University of Minnesota. St. Paul. MN 55108, USA -Smithsonian Institution. National Museum of Natural History, Washington, fJC 2001.^-7012, USA 'Zoologische Staatssainmlung M?nchen, M?nchhausenstrasse 21, D-81247 M?nchen, Germany Abstract. The superfamily Cocculinoidea is a group of marine, deep-water, limpet-like gastro- pods. Recent speculation surrounding their affinities has concentrated on their placement within the Ga.stropoda. However, phylogenetic relationships within the Cocculinoidea, especially the monophyly of families and genera within the group, remain poorly understood. Phylogenetic analysis of 31 morphological characters for 15 cocculinoidean taxa and 2 outgroups resulted in a single most parsimonious tree, length = 70, CI =0.62, and RI=0.7I. Monophyly of the Cocculinoidea, Ct)cculinidae, and the genera Cocciilina and Coccopigya was supported; Par- acocculina and Coccocrater were found to be paraphyletic. Character optimization demon- strates that many characters often cited as diagnostic of various taxa, are often homoplastic and/or synapomorphies at different hierarchical levels. Additional key words: morphology, cladistics, deep-sea The Superfamily Cocculinoidea is a group of ma- rine, deep-water limpets that inhabit primarily bathyal to hadal depths. Following a series of studies near the turn of the century (Dall J882: Dautzenberg & Fischer 1900; Pelseneer 1900; Thiele 1903, 1908, 1909), the anatomy and systematics of these limpets remained es- sentially ignored for more than 50 years. After this long hiatus, interest in the poorly known group was vitalized by the investigations of Moskalev (1971, 1976), Hickman (1983) and Marshal! (1986), with much of our detailed anatomical knowledge resulting from the work of Haszprunar (1987, 1988a, 1998). Currently, the superfamily is subdivided into 2 fami- lies: Cocculinidae DALL 1882 {Fedikovella, Coccocra- ter, Coccopigya, Cocculinu, MacLeaniella, Paracoc- culinu, and Teuthirostria) and Bathysciadiidae DAUTZENBERG & FLSCHEK 1900 (Bathysciadium, Bath- ypelta, Xenodoiita and Bonus). The Cocculinidae con- tains the majority of taxa that have been studied mor- phologically (Dall 1882; Thiele 1903; Ha.szprunar 1987, 1988a; Strong & Hara.sewych 1999). Published comprehensive anatomical accounts of other cocculi- noidean taxa are limited to that of Thiele (1908) and a study by Pelseneer (1900) that contained many errors (Thiele 1908; Haszprunar 1987, 1998). The relative scarcity of anatomical studies of this "Author for correspondence. E-mail: stronO 16@umn.edu large and diverse superfamily has rendered phyloge- netic relationships of its component taxa somewhat difficult to deterinine. Hypotheses of phylogenetic re- lationships have relied primarily on feeding biology and accompanying modifications of the radula and al- iinentary system (Haszprunar 1988a). However, mono- phyly of the Cocculinidae has remained untested and it has been suggested that familial separation of coc- culinids and bathysciadiids may not be justified (Hasz- prunar 1987). Moreover, current generic divisions within the Cocculinidae have been regarded as provi- sional given that distinguishing genera requires knowl- edge of both internal and external anatomy (Haszpru- nar 1987)?information that is lacking for most cocculinoidean species. Thus, monophyly of the fam- ily and the genera within it have remained uncertain. The goal of the present investigation is to combine the results of previous studies with new anatomical information to generate a phylogeny for the Cocculi- noidea based on morphological data. This will allow us to re-evaluate the current nomenclatorial status of the families within the group and begin to address the status of recognized genera for which anatomical in- formation is available. In addition, the character matrix provided herein can serve as a framework lor future investigations into the biology and evolutionary his- tory of this morphologically diverse group of deep-sea gastropods. (_ I - !-- - , 1- Cocculinoidea phylogeny 115 Methods Outgroups Despite iheir divergent morphologies, non-cladistic classifications generally have agreed on an archaeo- gastropod grade of organization for limpets Vk'ithin the Cocculiniformia HASZPRUNAR 1987. a group that in- cludes the Cocculinoidea and the Lepetelloidea, anoth- er superfamily of deep-sea limpets. Pelseneer (1900) suggested an affinity between Balhysciadhim and the "Docogk)ssa," but this was founded on his erroneous anatomical account of B. co.siiihiluiii. Thiele (1908) placed the Cocculinoidea within the "Archaeogastro- poda'' based on the presence of a modified rhipidog- lossate radula. Similarly, Haszprunar (1987, 1988a) concluded that the Cocculiniformia represent a primi- tive offshoot at the archaeogastropod grade of orga- nization, second to the Docoglossa. McLean (1985) hypothesized a more derived pt)sition for the Coccu- liniformia. intermediate between the archaeogastropi)d and mesogastropod grades. Recent cladistic studies have only intensified the de- bate. One study based on morphological data suggests that the Cocculiniformia may be diphyletic (Ponder & Lindberg 1996, 1997), with the Cocculinoidea forming the sister group to the Neritimorpha. and the Lepetel- loidea being a basal offshoot of the Vetigastropoda. Other analyses based on molecular data suggest a basal position for a monophyletic Cocculiniformia near the Patellogastropoda (Harasewych et al. 1997; Harase- wych & McArthur 2000). Thus, at present, there is no consensus t)n the his- torical cohesiveness of cocculiniform limpets, or their placement within the Gastropoda. For this analysis, 2 outgroups were chosen to reflect alternative competing hypotheses (Haszprunar 1987, 1988a; Ponder & Lind- berg 1996, 1997) of sister group relationship?Pseii- clocacculina ?^regciria as a representative of the Lepe- telloidea. and Theodoxiis fluviatilis representing the Neritimorpha. Characters Outgroup taxa were coded from Haszprunar (1988b) for Pseudococciilina grei>anu and Strong (in press) for Theodoxiis ?uvialilis. Anatomical data for the Bath- ysciadiidae were obtained from Thiele's (1908) ac- count of 5. paci?ciiin, supplemented with unpublished data (Haszpnmar). Teulhirostria cancellata and Fedi- kovella cayincmensis were coded using unpublished data (Haszprunar). All remaining species were coded primarily from Haszprunar (1987. 1988a, 1998) and Strong & Harasewych (1999) as well as several ad- ditional sources (Thiele 190.3, 1909; Hickman 1983; Marshall 1986, 1996; McLean 1987, 1992; Dantart & Luque 1994; McLean & Harasewych 1995; Leal & Harasewych 1999). Shell. Cocculinoideans share rather uniform shell morphology, consisting of a simple, cap-shaped shell. However, the position of the apex (character 2) may be subcentral to posterior (Figs. lA.B). Development of the periostracum (character 1 ) is also somewhat uni- form, but a spinose periostracum has been used to di- agnose members of the genus Ccncopigya (Jeffreys 1883; McLean &. Harasewych 1995) and a fringed per- iostracum occurs in the Bathysciadiidae. Reticulate protoconch sculpture (character 4) has figured prominently in distinguishing cocculinoidean taxa. But both Teiithirostrici cancellata (Moskalev 1976) and Macleaniella moskalevi (Leal & Harase- wych 1999) lack reticulate protoconch sculpture, plac- ing the utility of this feature for resolving higher order relationships in question. T. caiicellula and Fedikov- ellci cayinaiieiisis are unique among cocculinoideans in possessing reticulate teleoconch sculpture (character 3) rather than the smooth to beaded or pitted radial sculp- ture common within the group. External anatomy. Oral cuticular hairs (character 6), while known to occiu" in the Neritidae (Haszprunar 1987), are thought to comprise a synapomorphy t)f the Cocculinidae and are lacking in the Bathysciadiidae. Epipodial sense organs (character 5). previously hy- pothesized to be homologous to epipodial tentacles in vetigastropods and now believed to be homologous to epipodial sensory structures (Haszprunar, unpubl. data), are present in most cocculinids, but are lacking in Coccopigya. Subpallial glands (character 7) are var- iably developed in many cocculinoidean taxa, and are absent in the outgroups. Palliai cavity. The palliai cavity of cocculinoideans contains a number of structures that are highly modi- fied and unique among gastropods (Fig. IC-E). Most possess a folded pseudoplicatid gill (character 8) that is not composed of serially arranged leaflets, as are typical ctenidia. However, there are several exceptions. Macleaniella moskalevi possesses a small pseudopli- catid gill that forms a simple, ciliated papilla (Fig. ID). The gill of Fedikovella caymanensis comprises a series of respiratory lea?ets (Fig. IE), while Teiithiroslria cancellata bears a simple ciliary tract within the palliai roof which functions in ventilating the mantle cavity. The hypt)branchial gland (characters 9, 10) may be solid or, more typically, may be contained within a small to large pouch that ventrally encloses the rec- tum?the Manteldriise condition described by Thiele ( 1903). Development of this gland has been considered a useful feature for distinguishing species (Haszprunar 1987). Strong. Harasewych, & Haszprimar B Fig. 1. Exlernal morphology of cocculinoideans; shell (A-B) and mantle caviiy (C-E) characters. A. Shell with subcentral apex (character 2|()1) {Paiacocculimi cervae: modilied after Marshall 1986). ?. Sliell with posterior apex (character 2| 1 j) (Macleaniclla moskalevi; after Leal & Harasewych 1999). C. Large, folded pseiidoplicatid gill (character 8[01) and osphra- dium with discrete sensory epithelium (character 30[ll). D. Small, papillate pseudoplicatid gill (character 8|31) and os- phradium lacking discrete epithelium. E. Respiratory leaflets (character 8L2|). Abbreviations: (os) osphradium, (pg) pseu- doplicatid gill, (rl) respiratory leaflets. ^ - . . - Reproductive sy.stem. The hermaphroditic repro- ductive system of cocculinoidean.s i.s highly variable and has provided numerous characters for generic di- agnoses. It is characterized by a regionally differenti- ated gonad that simultaneously produces both egg and sperm. A seminal groove (character 14). absent in some taxa (Maclcuiiielld nioskulevi. Coccocraler uf^as- sizii), leads from the genital aperture to a copulatory organ (character 1 1 ) formed by or associated with the right cephalic tentacle, {Bathypelta pacificum. M. mos- kalevi, Tcuthirostrici cuiicelUita. Fedikovella caymci- ncnsi.s, Coccocrulcr rudiutu, C. aiiussizii. Coccopii^ya viii?ucnsis, C. Iiispidii). the foot (Parctcovculinu ccr- vae), or the oral lappet {P. laevis. Cocviiliiui haxteri, C. cowaiii. C. nvcLta. C. ruthhuni) (Figs. 2A-D). Sem- inal receptacles vary in number (character 13) from 1-2, and are found on the left, right, or both sides of the body (Figs. 2E?G). The glandular gonoduct may be massive or have gland cells in a tubular arrange- ment around a central duct (character \5). A palliai brood pouch (character 12), a rear-facing pocket within the tnantle roof, is present in all cocculinoideans ex- cept F. cayniuiiens?s. T. cunccllaHi. B. pari?ciini. and Cacculiiui cruii'smithi. Alimentary system. Radular morphology has been important in differentiating bathysciadiids from coc- culinids. The highly modified radula diagnostic of bathysciadiid taxa is characterized by the absence of marginal teeth and a broad, plate-like, acuspate rach- idian tooth. These features were autapomorphic and not included in the analysis. The most conspicuous radular character that varies among the included coc- culinoideans is the overhanging cusp of the rachidian. which may be present or obsolete (character 16). Rad- ular cartilages (character 18) comprise a single pair, in contrast to other basal gastropods with >2 pairs of cartilages. Jaws (character 19) typically consist of a single, small, unpaired plate on the anterior buccal cavity roof, while Teutliirostha ccincellalu possesses a robust jaw. Oulgroups often possess distinct, paired jaws. Although early studies reported salivary glands as absent in Cocculinoidea (Haszprunar 1987. 1988a; Strong & Harasew^'ch 1999), it is now recognized that the salivary glands (character 20) Form simple, glan- dular pouches on the posterior roof of the buccal cav- ity (Haszprunar 1998). However. Teitthirnstriii ccmccl- lata and Fedikovella caymaiiensis possess prominent to tubular salivary glands. In conjunction with the evo- lution of pouch-like salivary glands, the sublingual -^?r\ Cocculinoidea phylogeny drs \ Fig. 2. Reproductive sj'stem morphology of cocculinoideans; copulatory organ (A?D) and rcceptaculum seminis (E-G) characters. A. Copulatory organ on right oral lappet (character llfOl) {Cocciilinu ruthhimi; modified after McLean & Harasewych 1995). B. Modified right cephalic tentacle as copulatory organ (character I 1| Ij) (Madeaniella inoskalevi). C. Copulatory organ on right cephalic tentacle (character I l[ll) (Coccopigya hispida: adapted from Marshall 1986). D. Cop- ulatory organ on foot (character I 1(2]) (Paracocciilina cervae; after Marshall 1986). E. Single, right rcceptaculum seminis (Madeaniella moskalevi; after Strong & Harasewych 1999). F. Single, left rcceptaculum seminis [Coccopigya hispida: after Haszprunar 1987). G. Paired receptaculae (Coccidina ovata: after Haszprunar 1987). Abbreviations: (btg) basitentacular gland, (co) copulatory organ, (f) foot, (ol) oral lappet, (t) cephalic tentacle. cavity ha.s become highly glandular (character 18). The conligiiration of the fore- and midgut in Cocculinoidea displays some intriguing variability (see discussion be- low). In most taxa, the posterior esophagus is deflected to the left and opens to the midgut posteriorly (char- acter 21 ), (Mucleanielki moskalevi, Paracocculiiia. Coccopigya, Coccocrater, Cocculina). However, in F. cayiuancnsis, T. cancelUita, and Bathypelta pacificiini, the esophagus is straight, opening ventrally to the mid- gut (Fig. .-^A.B). Circulatory system. The circulatory system in Cocculinoidea is characterized by a rectum ihiit does not penetrate the ventricle (character 22). The aoitic vessel (character 23), a contractile vessel connecting the pedal and cephalic hemocoels, is uniquely devel- oped in cocculinoideans: it remains unknown whether this feature occurs in bathysciatliids. A bilobed hemal gland (character 24) is cominonly associated with this vessel, but is absent in Bathypelta pacificuni. Fedikov- etla cayinanensis. and Teiithirosiria cancellata: the gland may be small or massive (character 25). Nervou.s system and sensory structures. Coccu- linoideans display unusual diversity in the configura- tion of ganglia around the circuin-esophageal nerve ring (character 26) and visceral loop (character 27): 1) Fig. 3. Alimentary system morphology of cocculinoideans. A. Alimentary system with reduced jaw. pouch-like salivary glands and csophageal bending (Mtwleaniella inoskalevi: modified after Strong & Harasewych 1999). B. Alimentary system with robust jaw, tube-like salivary glands, and straight esophagus (e.g. Teuthiroslriu caiicidlata). Abbrevi- ations: (dep) ducts of esophageal pouches, (dgd) digestive gland duct, (c) esophagus, (gs) gastric shield, (inl) intestine, (j) jaw, (sgl) salivary gland, (sto) stomach. 118 A Strong, Hiirasewych, & Has/.prunar c Fig. 4. Nervous system morphology of cocciilinoide;ins. A. Central nerve ring (with subesophageal. supraesophageal and osphnidiai ganglia on left, visceral ganglion on right, and unlused supiaesophageal and visceral ganglia) and weakly dyslenoid (e.g. Mtich'tiniclla moskalcvi: modilicil alter Strong & Hara.sewych 1999). B. Central nerve ring and hypoalhroid on left and right (e.g. Coci(>pif>ya hispida: after Has/.prunar 1987). C. Shifted nerve ring (with subesophageal and osphradial ganglia near midline, and supra-esophagcal ganglion fused with visceral ganglion on right) weakly dyslenoid (e.g. Cocculiiia ovala: after Has/.prunar 1987). Abbreviations: (bg) buecal ganglion, (eg) cerebral ganglion, (osg) osphradial ganglion, (pdg) pedal ganglion, (pig) pleural ganglion, (sbg) subesophageal ganglion, (spg) supraesophageal ganglion, (vg) vi.sceral ganglion. hypoathroid on the left and right, with un-fused supra- esophageal and visceral ganglia (Fig. 4A) (Batliypcltci pacificuni, Coccopigya. Paracocculina. Coccocraier), 2) weakly dystenoid with un-fii.sed visceral and supra- esophageal ganglia (Fig. 4B) {Macleauiella moskalevi, Teuthirosirici cancelluta. Fedikovclla caymanensis), and, 3) weakly dystenoid. with fused visceral and sii- pra-esophageal ganglia (Fig. 4C) iCocculuKi). In ad- dition, the sub-esophageal. supra-esophageal and os- phradial ganglia may be located lel'l of the midline (C?ccocrater, Coccopiaya, Paracocculina. M. mos- kalevi, T. canccllata, F. cayinanensis, B. pacijicum). or may be displaced to the right (CoccuHna). However, the shift in position of these ganglia to the right and the Fusion of the sub-esophageal and visceral ganglia have an identical distribution among the taxa studied in this analysis, occurring only in Cocculina. Thus, these characters are not likely to be independent and are subsumed within a single character (character 27). Sensory structures include osphradia, statocysts, and modified eyes. Most cocculinoideans possess a distinct osphradium in the palliai roof (character 28); however, Macleaniella iiio.skalevi lacks a di.screte osphradial ep- ithelium and the osphradium is lacking entirely in Bathypellci pacificuni. Cocculinoideans are unusual among basal gastropods because they possess stato- cysts bearing a single statolith (character 29) (Ponder &. Lindberg 1997). The only exception is M. moskal- evi, which is polymorphic for this feature. Eyes may be ab.sent, present or modi lied into the mucus-.secreting basitentacular gland with a narrow to broad duct (char- acters 30, 31). Phylogenetic analysis The data matrix comprises 31 characters for 15 coc- culinoidean taxa and 2 outgroups, Tlieotlo.xus?uviatilis and Pseudococculina fiiegaria. Balhypelta pacificum is the single bathysciadiid for which comprehensive comparative anatomy is known and was included in the analysis to assess monophyly of the family Coc- culinidae. The data matrix is listed in Table 1; char- acter descriptions are listed in the appendix. The poly- morphic character relating to the condition of the statocysts in Macleaniella ino.skalevi is indicated with "'?'"' in the data matrix and was analyzed as both "()" and "1": choice of coding had no effect on the result. Unknown information is indicated with "7": inappli- cables are indicated with "-?'. Morphological characters were coded using reduc- tive coding (Wilkinson 199,5; Strong & Lipscomb 2000) and edited with DADA 1.97 (Nixon 1995). The matrix was analyzed using NONA 1.6 (Goloboff 1993). which suppresses persistent arbitrary resolu- tions (Nixon & Carpenter 1996). Tree .searches were accomplished using the hetn-istic search option "hold 100; hold/25; mult-''20." All characters were analyzed as unordered. Character optimizations were examined in CLADOS (Nixon 1995) under ACCTRAN. Bremer support was calculated with TreeRot (Sorenson 1999) Cocculinoidea phylogeny - ? ? - . ^^^ Table 1. Data matrix for 15 cocculinoidcan taxa and 2 outgroups. Inapplicable characters are indicated with "-"; missing characters are indicated with "?"", Polymorphic character is indicated with '?*'". Taxa i Characters 2 3 Theodoxiis ?iivialilis Psc'?idococciiliii?i gregaria Bathypelta pacificum Coccocrater agassiz.ii Coccocraler radiata Coccopigya hisiJida Coccopigya viminensis Cocciilinu haxteri Cocculiiui ci/wani CiKculina craigsnnlhi C/KciiUiui ovala Cocciilina rathhiini Fedikovella cayinaiieiisis Macleai?ella iiioskalevi P?irac?>cciiliiia cervae Faracocciilina laevi.s Teutliiroslria cancellala ? - - ? C 0 14 0; 1 0 0 ?' '^ 0 0 0 ? 1 000'! .. 2 ] ? : 0 21110 01011 01211 ooc ? ?. 000 . 0 1.3_ _. 01001 010:11 C 0 01 1 C 20 ?. 0 0 " 0 00' -' 0 ?'. ? " - 10 0 ? ? 10 010 1 i 0:1 11010 10010 10011 I o ? ? ^ 10010 1^20- 2100- l:loi 1 ? I 0 1 ! 030- 3 0 312 ?] C - ! 2 ^ 02] 0 000 1 2' U i 1 _ "_. u 11110 01111 01111 "? O'lO 0.010 ^0210 11200 21 110 0'! : 1 : 0.10 000 ? C2 02 0 '1 "?000 01000 01000 . -000 11000 11000 11000 01000 01 000 01000 01101 01000 11000 ?I -'.0 0 0 0 .?.'? ' - 0 0 0 0 - 0000- 01?0 - 1111? 11110 11111 11110 11110 1111 0 inc- lino 11110 01 lo- in ? .- 11111 1 - ? VI o : o - 10100 - lO?lO - 10000 - 10101 1 : ?? ? 00 - 10:01 1 10101 1 01101 1 01101 1 01100 - 01101 1 oil 01 o 00"00 - 0 0 *i o 10101 1 : o 1 o I 1 OIJLOO - using a heuristic search option with 10 random addi- tion sequences and tree-bisection-reconnection. The cladogram was drawn using WINCLADA (Nixon 1999). Results A single rnost parsimonious tree was obtained with a length of 70, CI =0.62, and RI = 0.71 (Fig. 5). The analysis supports monophyly of the Cocculinoidea and the Cocculinidae. Fedikovella caymanensis and Teit- ihirostria cancelUitu are sister groups, forming the most basal cocculinid offshoot; MucleanielUi rnoskal- evi is the sister group to all remaining cocculinids. Arnong the genera represented by more than a single exernplar, monophyly of Coccopii^yci and Cocculina is supported, but Coccocraler and Paracocculina are paraphyletic. Breiner support for all nodes is low, with values of <3 (see Fig. 5). The node supporting monophyly of the Cocculinoidea is supported by a Bremer value of 3; the node supporting monophyly of the Cocculinidae is supported by a Bremer value of 1. The Cocculinoidea is highly distinct compared to outgroup taxa and is united by numerous synapomor- phies, including: a teleoconch with smooth radial ribs (3|0|). reticulate protoconch sculpture (4| 11), the pres- ence of a subpallial gland (7| 11), a pseudoplicatid gill (8|0|), a single, right receptaculum seminis (13|2)), a gonoduct with massive glands (15|0J), a single pair of radular cartilages (17|1|), a single, small jaw (19|0|), a rectum that does not penetrate the pericardium (22| I I), and the presence of the aortic vessel (23[l |). Optiniizalion of the aortic vessel is ambiguous at this node due to missing data for Bathypelta pacificum. Monophyly of the Cocculinidae is weakly supported by 2 characters: the presence of oral cuticular hairs (6| 11), and a circum-esophageal nerve ring that is weakly dystenoid (26|0|). The latter only optimizes to this node under ACCTRAN. The presence of cpipodial tentacles (5| 11) also oplirnizes to this node under DEL- TRAN, but optimization is ambiguous due to variation arnong the outgroups. New data for Teutliirostria cancellata and Fedikov- ella caymanensis confirm the distinctiveness and co- hesiveness of these unusual genera. They are united unambiguously by: a reticulate teleoconch sculpture (3|3|), a non-glandular sublingual cavity (I8|IJ), and prominent to tube-like salivary glands (2()|I|). Con- dition of the gill (character 8) is dependent upon op- timization rrielhod. reflecting Ihe aulapornorphic char- acter states in both taxa. The node uniting Macleaniella ninskalevi and all re- maining cocculinids, excluding Teutliirostria cancel- lata and Fedikovella caymanensis, is supported by 4 synapomorphies: the presence of a palliai brood pouch (12| 11), a deflected posterior esophagus (21[11), a he- mal gland (24| 11), and a basitentacular gland (30LI |). Optimization of the condition of the hemal gland and basitentacular gland at this node demonstrates a problematic phenomenon associated with reductive ct)ding. noted by Strong & Lipscomb (2000), namely, the decoupling of presence/absence characters and 120 Strong, Harasewych, & Haszprunar K ! 2 5 U>2X ^^Theodoxusfluviatilis ^ ^?..'?'\ ' . WPseudococculina gregaria ?Bathypelta pacificum Fedikovella caymanensis "> ^ "" "^ ? ^ ^. -' ' i' 4 7 s 1 ;i 1 ^? -{j-[]-|-{H"^'S'?''/^"'05?r?a cancellata HA 1 .4 7 S 13 13 17 l'>22 23 iimmii o 1 I () 2 ? 1 0 1 1 J I ? ?) ! () 0 1 (> 3 K I S 20 H H44 o 0 3 1 1 4 I4."?l W\Macleaniella moskalevi o o I I \Paracocculina cervae I 2 2 ! 24 3() HW 1111 H il.. 'n "n ? {H}^<^'"?<^occw//?? laevis riHrT ' (> 0 I Coccopigya hispida H4 W W;' 3- M Vi S' a a "\^^-Coccopigya viminensis o o -Coccocrater radiata 14 r[]-Coccocr?7f?r agassizii Cocculina ovata 3 1 -|}Cocci///?fl rathbuni 12 24 3() -|-|-|-Coccw/z?a craigsmithi W Cocculina baxteri YYCocculina cowani n o o o t????* s a Fig. 5. Single most parsimonious ?ee. lcngth = 7(). CI = 0.62. RI = ().71. Characters are optimi/ed using ACCTRAN. Blacl< liash-marks indicate forv/ard changes: grey hash-marks indicate forward homoplasies. Values in hold at nodes indicate Bremer support. Cocculinoidea phylogeny 121 their modiiiers. For example, the weak development of the hemal gland (character 25|0|) and the broad size of the basitentacular gland duct (character 31|1|) should optimize at this node as well; observations of absence and presence do not exist in isolation. How- ever, because of missing values at the base of the tree reflecting absence of these features, development of the hemal gland and size of the basitentacular gland duct are optimized as symplesiomorphies. As noted by Strong & Lipscomb (2000), this should have no mis- leading influence on tree construction, but is problem- atic from the point of view of character interpretation. Discussion Character analysis The utility of features that have figured in the supra- generic classification of Cocculinoidea was assessed in light of these results, namely, protoconch sculpture, radular and salivary gland morphology, and presence/ absence of oral cuticular hairs, pseudoplicatid gill, and brood pouch (Haszprunar 1987). Features routinely cited as diagnostic of genera were evaluated as well, including development of the periostracum. teleoconch sculpture, presence/absence of epipodial sense organs and subpallial glands, position of the copulatory organ, arrangement of the reproductive glands, and condition of the nerves (Marshall 1986: Haszprunar 1987; Mc- Lean & Harasewych 1995; Leal & Hara.sewych 1999; Strong & Harasewych 1999). The presence of oral cuticular hairs is a feature com- monly cited as diagnostic of cocculinid taxa. In the present analysis, this feature is uniform and confirmed as a synapomorphy of the family. However, other fea- tures are not so straightforward. For example, reticu- late protoconch sculpture has been used to characterize cocculinids and bathysciadiids (e.g., Haszprunar 1998). The fact that Macleaniellu iiiosktilevi (Leal & Harasewych 1999) and Teiithirostria cancelluta (Mos- kalev 1976) among others lack this characteristic sculpture casts doubt upon the utility of this feature in the higher order taxonomy and phylogeny of the group. Cladistic analysis indicates that reticulate pro- toconch sculpture (4|1J) indeed unites the Cocculino- idea. Consequently, although the feature is homoplas- tic within the group, it docs represent a synapomorphy of the superfamily. Condition of the gill is yet another character with uncertain status in light of new anatomical investiga- tions. Until recently, the presence of a pseudoplicatid gill was thought to comprise a synapomorphy of the Cocculinoidea (Haszprunar 1988). However, Fedikov- ellu caymanensis and Teiithirostria cancelluta are now confirmed to possess unique gill morphologies; F. cay- manensis possesses respiratory leaflets and T. cancel- lata bears only a ciliary tract (Haszprunar, unpubl. data). Despite the unique conditions in these taxa, the analysis reveals that, similar to protoconch sculpture, the pseudoplicatid gill indeed represents a cocculint)i- dean synapomorphy but is variable and not diagnostic of cocculinioidean taxa. Reproductive characters are most often used in ge- neric classification of cocculinoidcans. However, the unique palliai brood pouch has been used at higher hierarchical levels to distinguish the Cocculinidae from the Bathysciadiidae. In addition to bathyscia- diids, new data has confirmed that Teiilhirostria can- cellala and Fedikovella caymanensis lack the brood pouch (Haszprunar, unpubl. data), further distinguish- ing these taxa. This character supports the basal place- ment of the Bathysciadiidae, F. caymanensis and 7'. caiicellata. and unites all remaining cocculinids. Thus, a palliai brood pouch does not unite the family but is a synapomorphy of a more exclusive cladc than pre- viously thought. Among alimentary characters, absence of marginal teeth, producing the characteristic "bathysciadiid" radula, is autapomorphic for Batliypelta pacijicum and, therefore, not included in this analysis. However, such characters are likely to be important in the future for testing monophyly of the Bathysciadiidae. The pres- ence of prominent to tube-like salivary glands is unique to Teuthirostria cancellala and Fedikovella caymanensis, also highlighting the distinctiveness of these taxa. Optimization of simple, pouch-like salivary glands is ambiguous and interpreted as plesiomorphic within the Cocculinoidea because of the presence of pouch-like glands in Pseiidococciilina t^ref^aria and the absence of glands in Theodoxiis fluvial His. For this character, determination of its status as a synapomor- phy or symplesiomorphy awaits resolution of the sister group relationship to the Cocculinoidea. Condition of the nervous system is often given high systematic value, not only within the Cocculinoidea, but within the Gastropoda in general, due to its con- servatism. Historically, classifications have relied on such presumably conservative characters, at times to the exclusion of all other information, reflecting the assumption that such characters are reliable in delin- eating monophyletic groups. This analysis provides an interesting case study that highlights the pitfalls of such approaches. Although the shift of the nervous system to the right, with the concomitant fusion of the supra-esophageal and visceral ganglia, unites Coccu- lina, the evolution of a dystenoid nerve ring primarily denotes grades rather than clades. Under ACCTRAN, the hypoathroid condition is interpreted as plesio- morphic within the group with 2 independent deriva- t2i Strong, Harasewj'ch, & Has/.prunar tions of the dystenoid condition, once in the grade in- cluding Tciithirastria cancellaid. Fedikovellu cayniciiic/isi.s, and Mciclcanirlla nioskalcvi, and once in the Cocciiliiui clade, supporting monophyly of the lat- ter, with a reversal le? the hypoathroid condition in the grade including Paracocciilina. Coccopifiyu. and Coc- cocnitcr. Fn this instance, conditions of the nervous system are homoplaslic and do not identify exclusively monophylctic taxa. In general, features commonly cited as useful for suprageneric classification of cocculinoideans have demonstrated a consistent utility in supporting large clades. Yet. the refinement of character distributions for the pivotal taxa Fedikovella cuyinaiicnsis and Tcu- thirosiria canccllulci. as well as the basal placement of these taxa with the Balhysciadiidae, have an important influence on character interpretation. Characters pre- viously thought diagnostic of superfamily membership are revealed to be synapomorphies of more exclusive clades than previously thought (e.g.. palliai brood pouch). Other features are now confirmed to be ho- moplastic (e.g., nervous system). However, the anal- ysis illustrates that many such characters, although variable, remain important synapomorphies in higher order systematics of the group (e.g., reticulate proto- conch sculpture, condition of the gill). For genera, this analysis indicates that shell char- acters are of rather limited utility, yet provide impor- tant synapomorphies at lower hierarchical levels. With rare exception, cocculinoideans possess smooth, radial ribs and a simple periostracum. Elaboration of the per- ioslracum has occurred independently in Biilhypellci pacipciim and Coccopi?^yci, but the presence of a dis- tinctive, hirsute periostracum supports monophyly of the latter The periostracal spine bases may be asso- ciated with distinct pits along the radial ribs, which are uniquely derived in Coccopigyu. Reticulate teleoconch sculpture supports monophyly of Tcullnrostria cun- cellata and Feilikovcllci cayinanetisis. Features of external anatomy and structures within the palliai cavity have been emphasized in generic classifications because they are readily accessible and visible with standard I ght and scanning electron mi- croscopy. In contrast to their standard use. such fea- tures are homoplastic ;uid/or do not consistently pro- vide unambiguous synapomorphies for genera as currently conceived. For example, loss of epipodial sense organs has occurred independently in bathyscia- diids and Corcopi^^yu. but supports monophyly of the latter. Loss of the subpallial gland has occurred within Teulhirostr'ui cancelhiln, Cocciilina, and Coccocratcr, uniting the latter genera in a large clade. The presence of a hypobranchial gland pocket (Manteldr?se condi- tion) unites a large clade including Coccocraicr, Coc- ('>pii>yu, Pciracocciilina, and Cocvuliiia. Thus, with rare exception these features unite large clades. Even when they indeed represent synapomorphies of genera, they are commonly homoplastic at higher taxonomic levels and cannot be used in isolation to diagnose monophyletic groups. Similarly, the condition of the copulatory organ is capable of resolving several monophyletic groups but is not always diagnostic of current genera. The use of a modified or unmodified right cephalic tentacle as a copulatory organ is supported as plesiomorphic within the Cocculinioidea and is found in many taxa includ- ing Balhypclta paci?cum, Teulliiro.stria cancellaid. Fe- dikovella cayinanensis. Macleaniella inoskcdevi, Coc- cocrater, and Coccopi,^ya. Paracocciilina laevis is now confirmed to possess a verge on the right oral lappet (Has/.pnmar. unpubl. data), which has evolved independently in Cocciilina. A pedally innervated cop- ulatory organ is unique to P. ccrvae. Detailed copu- latory organ structure, although often autapomorphic and thus not included here, may become informative in the future with the inclusion of more taxa. Conditions of the receptaculum seminis appear use- ful for recognizing monophyletic groups, but also are rarely indicative of generic level taxa. For example, a single, right receptaculum seminis is a synapomorphy of the Cocculinoidea, shared by Ba/liypella paciftcuin, Fedikovella caynuiiiensis. Macleaniella mo.skalevi, and Coccocratcr radiola. A single, left receptaculum is present in TenUnro.siriii cancellaia and has evolved in- dependently in the clade uniting Parucocculina and Coccopii^ya. The presence of paired receptaciilae has evt)lved once and suppt)rts a grade, not a clade, in- eluding Coccocratcr ai^assizH. Cocciilina ovala, and C. rathhuni. Similarly, a massive glandular gonoduct is a synapomorphy of the Cocculinioidea; tubular glands unite a clade including Cocciilina cr(ii?>sniilhi. C. cowuni. and C. baxleri. Thus, in contrast to their standard use. these features denote grades or supra- generic clades and cannot be used in isolation to re- liably indicate phylogenetic affinity. Non-tor.sional asymmetries Non-torsional rearrangements of organs or organ systems seem to be a common theme in the history of the Mollusca (Lindberg & Ponder 1996). Although poorly studied among gastropods, the be.st-documented example is the rift limpet Neonipliaht.s fretlerae. in which asymmetries are apparent in the digestive sys- tem, nerves and pericardium (Fretter et al. 1981). Lindberg & Ponder (1996) first discussed the phylo- genetic significance of such rearrangements, empha- sizing higher taxt)nomic levels, but also drew attention C?cculinoidea phylogeny 123 l? digestive system asymmetries apparent between le- pelelloideans and coccnlinoideans as described by Has/prunar (1988a). Despite the fact tiiat this and oth- er cited examples involve taxa that have assumed a limpet-like morphology, Lindberg & Ponder (1996) stressed that such rearrangements arc unlikely to be restricted to limpets, nor necessary for the adoption of a limpet-like habit. Indeed, Strong (in press) has dem- onstrated that such asymmetries are capable of provid- ing important phylogenetic information in the Caeno- gastropoda, cutting across patterns of shell shape. The intriguing revelation of the present analysis is that configuration of the alimentary system provides impt)rtant synapomorphic information within the Coc- culinoidea. A change in the disposition of the alimen- tary system apparently has been produced through a non-torsional rotation of the organ system along a lon- gitudinal axis. The manifestations of this process are evident in the morphology of the posterior esophagus (straight vs. deflected) and position of the esophageal aperture (ventral vs. posterior) (Fig. 3). Here, esoph- ageal deflection (character 21), and the inferred rota- tion of the midgut, bringing the esophageal aperture from a ventral position into a posterior position, forms a synapomorphy uniting all coccnlinoideans to the ex- clusion of TcLithirostria cunccUuta. Fedikovclla cay- inanenxi.s, and Balhypeltu pacificum. These latter taxa display the plesiomorphic condition?a straight esoph- agus opening ventrally to the midgut. Thus, the present analysis confirms the utility oi'such characters at lower taxonomic levels. Conclusions Thorough morjihological investigation of cocculi- noidean taxa is still in its infancy (Has/prunar 1987, 1988a, unpubl. data: Strong & Harasewych 1999). New character combinations are revealed with each study, even among features thought to be conservative at higher taxonomic levels within the Gastropoda, such as the nervous system. Thus, despite its size, the group is extraordinarily morphologically diverse. Moreover. the 15 species for which such information is available represent 8 of 10 nominal genera, and only 23% of the ?60 cocculinoidean species presently known (Haszprunar 1998). The Bathysciadiidae, in particular, remain poorly known. Given this important caveat, adequacy of the current generic classification must be questioned in light of the results of this cladistic analysis. In particular, the genera Paracocculina and Coccocrater were found to be paraphyletic. However, given the low Bremer sup- port for these nodes, restructuring the classification is premature and may be overturned with additional an- atomical investigations. On the other hand, new mor- phological data for Fedikovella cciynuineiisis and Teu- thirostrici cancellutd reveal the anatomical distinctiveness of these taxa: cladistic analysis sup- ports a sister group relationship between them and a basal placement within the Cocculinidae. In addition, monophyly o? the Cocculinidae is confirmed. Al- though the node separating Cocculinidae and Bathys- ciadiidae is supported by only 2 characters and has a Bremer value of 1, many features were rendered au- tapomorphic by the inclusion of only a single bath- ysciadiid representative and were not included in the analysis (e.g., unique features of aUmentary system). Thus, this study cannot address the justification for familial separation of these groups. Character analysis demonstrates that features iden- tified as "diagnostic" of cocculinoidean taxa, are use- ful in delineating monophyletic groups within the con- text of a phylogenetic analysis, but are often homoplastic or are synapomorphies at different hier- archical levels than previously thought. Consequently, this analysis emphasizes the fact that it is not reliance on a few essential diagnostic features,/J?T .vc, that pro- vides the key to identifying groups, but the unique combinations of plesiomorphies and apomorphies shared by those taxa as revealed through phylogenetic analysis. 'I Acknowledgments. We gratefully acknowledge the com- ments of two reviewers. This is Smithsonian Marine Station at Fort Pierce Contribution 544. Appendix i Characters used in phylogenetic analysis. 1. Periostracum, (0) Smooth, (I) Fringed, (2) Spi- n?se. 2. Apex position, (0) Subcentral, (1) PosteriiH'. 3. Teleoconch sculpture, (0) Smooth radial ribs, (1) Pitted radial ribs. (2) Beaded radial ribs, (3) Re- ticulate, (4) Concentric. 4. Protoconch sculpture, (0) Smooth, (1) Reticulate. .5. Epipodial sense organs, (0) Absent, (1) Present. 6. Oral cuticular hairs, (0) Absent, (I) Present. 7. Subpallial gland, (0) Absent, (1) Present. 8. Gill condition, (0) Pseudoplicatid, (1) Respiratory and ventilatory leaflets, (2) Solely respiratory leaf- lets, (3) Ciliary tract. 9. Hypobranchial gland pocket, (0) Absent, (1) Pres- ent. 10. Hypobranchial gland pocket, (0) Small, (I) Large. 11. Copulatory organ, (0) Oral lappet, ( 1 ) Right ce- phalic tentacle, (2) Foot, (3) Cephalic lappet. 12. Palliai brood pouch, (0) Absent, (1) Present. )? 124 Strong. Harasewych. & Haszpiunar 13. Receptaculum seminis, {()) Paired, (I) Single left, (2) Single right, (3) Palliai oviduct. 14. Seminal groove. (0) Absent, (I) Present. 15. Gonoduct. (0) Massive. (I) Tubular. (2) Not glan- dular. I 16. Rachidian, (0) Cusped, (I) Acuspate. 17. Radular cartilages. (0) 7. (1) 1 pair, (2) 2 pairs. 18. Sublingual Cavity. (()) Glandular, (I) Non-glan- dular. 19. Jau's, (0) Single small, (1) Single robust, (2) Paired. 20. .Salivary Glands, (0) Simple pouches, (I) Promi- nent to tube-like. 21. Esophageal deflection. (0) Straight, (I) Deflected. 22. 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