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148 presented herein. First, we give an annotated catalogue of the ZMB type material with notes on the type specimens, including their original status and references (i.e. author and bibliographic source), type localities, the nature of the extant type material and current systematic placement and taxonomic status of the taxa. Second, we aim to place these taxa within the framework of the current systematic knowledge on the phylogeny of aplacophoran molluscs by reviewing the development of this knowledge, including an outline of the results of recent cladistic analyses. This annotated catalogue of aplacophoran types continues earlier compilations of molluscan material in the ZMB (see bibliography of R. Kilias (1929–1999) in Glaubrecht 2001). It adds to those catalogues of other less species-rich groups, such as Polyplacophora (Kilias 1995a), Scaphopoda (Kilias 1995b), but also Cephalopoda (Glaubrecht & Salcedo-Vargas 2000; Köhler & Glaubrecht 2004), whereas the extremely rare Monoplacophora are not represented in the ZMB. Brief review of the history of classification in aplacophoran molluscs Seit ich angefangen, mich mit der Anatomie von Mollusken zu beschäftigen, ist es mein Bestreben gewesen, über die Verwandtschaftsbeziehungen des ganzen Stammes wie einzelner Gruppen ins Klare zu kommen. Johannes Thiele, 1894: 222 Representatives of the two major aplacophoran molluscs were first published from Scandinavian waters in 1845 and 1875, respectively, and subsequently recognized increasingly often in dredged material from oceanographic expeditions. For the first time, Heinrich Simroth (1893a) not only discussed the then available morphological data on aplacophorans but added tentatively a first “Versuch eines Systems” in listing the known genera according to their geographical occurrence, i.e. as nordic and mediterranean forms. This not being a systematization in the strict sense, it was an early approach more to compile rather than to classify the described taxa; for his extended systematization see Simroth (1893b: 226–233). Thiele (1902c) is often cited with the conclusion from his first account on the systematic placement of the Solenogastres in connection with the phylogeny of the Mollusca that aplacophoran species are not molluscs (e.g. Scheltema 1996: 57). Indeed, # 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Glaubrecht, M. et al., Aplacophoran Mollusca in the Natural History Museum Berlin in his final statement Thiele (1902c: 455) proposed explicitly (and printed in bold) that “Solenogastres are a group of worms closely related to annelids and gordiids, connecting those – by the relationship of the uterus and the pericard as well as the inital stages of a radula organisation – to the molluscs, among which the chitons are particularly closely related to them through the preservation of the lateral cords [of the nervous system]”; [translated from the German original – M.G.]. In his phylogenetic tree, printed as text-figure in Thiele (1902c: 438) and following contemporay perception of phylogenetics, he depicted this hypothesis by placing Solenogastres among the Vermes, as a late offshoot from a branch eventually leading to the Mollusca. However, Thiele’s reservations as to the placement of Solenogastres within molluscs go back to his earliest accounts published in 1891 and 1892, when he suggested that “Wurmmollusken” (i.e. worm-shaped molluscs) are the Amphineura of H. von Ihering with the two constituent orders Solenogastres or Aplacophora and the Polyplacophora (Thiele 1892). He viewed Solenogastres as more primitive and the amphineurans in an intermediate and transitional position – as socalled “Ûbergangsformen” (Thiele 1892) – between annelids and molluscs (see also Thiele 1891: 521). Later, Thiele (1895: 867) concluded from his ongoing dissections of aplacophorans that “Solenogastres are no molluscs because they lack the typical molluscan characters” [translated from the German original]. In addition, Thiele (1895: 869) suggested to transfer Solenogastres to the “worms” (i.e. Annelida), thus, also breaking up the Amphineura. He continued to stress this view for the rest of his life, as is evident, for example, from his accounts on Solenogastres in Thiele (1925: 13), where he perceived them – according to then prevailing thinking – as “phylogenetische Ausgangsform”, i.e. not only as hypothetical but still extant evolutionary ancestor to the Mollusca (his “Elternform”, see Thiele 1891: 480), with close affinity now to turbellarian worms. Thiele’s position is also evident from the introductory statement in his last contribution on Solenogastres (Thiele 1933: 144). He was followed in his view, for example, by Nierstrasz (1909–1910) and Odhner (1921) but not Heath (1911), while e.g. Hans Hoffmann (1929) expressed an opposed opinion in his critical evaluation of the “Amphineura” discussion; for an historical review see e.g. Hoffmann (1929, 1937) and in particular Salvini-Plawen (1967, 1972).
Mitt. Mus. Nat.kd. Berl., Zool. Reihe 81 (2005) 2 / http://museum-zool.wiley-vch.de 149 It was only consequent from this, albeit erroneous, hypothesis that Thiele (1929) did not include aplacophorans in his Handbuch der Systematischen Weichtierkunde, which started accordingly with the Loricata Schumacher, 1817 (¼ Polyplacophora Gray, 1821) interpreted by him as most primitive and true representatives of the phylum Mollusca. In the second volume of his Handbuch, Thiele (1935: 1074) for the last time outlined the phylogeny of the Mollusca, stating that the Solenogastres cannot be viewed as derived from shelled animals due to, for example, their peculiar hautmuskelschlauch (p. 1073) and because of other characteristic anatomical features, thus repeating that they are to be perceived as “Vermes” and excluded from the Mollusca (p. 1074). Two conclusions can be drawn from this. First, evidendently, Thiele and his contemporaries struggled with quite similar problems of molluscan classification as we still do over a century of zoological systematics later, viz. monophyly vs. paraphyly of the aplacophorans, their relationship to Polyplacophora within the Amphineura and/or Aculifera concept and the ancestry of the Mollusca within the metazoans, in particular their relationship with Annelida. And second, Thiele’s erroneous assumption of Solenogastres being “Vermes” resulted in the deposition of aplacophoran material of the ZMB, and hence the late re-discovery of it, in the “Vermes” department that initiating this annotated type catalogue. The first half century of research on aplacophoran classification was dominated by the practice to consider all “worm-like” molluscs as Solenogastres, thus including also those taxa later to be distinguished as Caudofoveata; see e.g. treatments by Simroth (1893b), Thiele (e.g. 1902c, 1913c), Nierstrasz (1908) and Heath (1911). Thiele (1913c) distinguished four taxa among this paraphyletic group, the Chaetodermatidae, Neomeniidae, Proneomeniidae, and Lepidomeniidae. Later, Thiele (1932) suggested to separate five families within the aplacophorans (all considered by him to represent Solenogastres), viz. Neomediidae, Proneomeniidae, Gymnomeniidae, Lepidomediidae and Crystallophrissontidae. The latter, however, represents Chaetodermomorpha according to current knowledge which were subsequently separated by Boettger (1956); see e.g. Fischer-Piette & Franc (1960) and Salvini-Plawen (1967). Following Thiele’s era, Sigurd Hoffman (1949) not only contributed essentially new information on the then widely neglected aplacophoran groups but also discussed at length phylogenetic pathways and higher classification based on comparative investigations. Others, such as in Germany Hans Hoffmann (1929, 1951) stated not to separate aplacophorans from the Mollusca and proposed to view the Solenogastres as most “primitive” group within this phylum. It was then Boettger (1956) and later in particular Salvini- Plawen (1967, and subsequent publications) who took up, after almost half a century of neglectance of this important molluscan group, again the controversies as to the monophyly and phylogeny of “Aplacophora”. In the absence of cladistic analyses, most authors long followed the general assignment of all “worm shaped” molluscs as two clades Solenogastres or Neomeniomorpha (or Ventroplicida Boettger, 1956 which is a later naming) and Caudofoveata or Chaetodermomorpha within a monohylum Aplacophora. In contrast to these classifications of “Aplacophora” or “Aculifera”, Salvini-Plawen (e.g. 1972, 1985, 1991) has, early and repeatedly, argued that aplacophorans are paraphyletic or diphyletic, respectively (see below). Furthermore, despite revision (Salvini-Plawen 1978) the systematic relationships remained partly unresolved within Solenogastres, and the status of some families was poorly understood, as was recently shown, for example within the Cavibelonia by Salvini-Plawen (2004). Earlier suggestions to separate three families most likely did not reflect natural phylogenetic lineages (Salvini-Plawen 1967). According to the systematization suggested by Salvini-Plawen (1978; see also phylogram in Salvini-Plawen & Steiner 1996: 31), four orders are to be distinguished within the Solenogastres, viz. Pholidoskepia, Neomeniamorpha (both as Aplotegmentaria) and Sterrofustia plus Cavibelonia (these two as Pachytegmentaria). Thus, the Cavibelonia, in which 11 genusgroup or families are now distinguished, replaced the Proneomeniidae s.l. and most of Neomeniidae s.l. in former systems. For discussion and references see Salvini-Plawen (1978, 2003, 2004). This systematization is followed herein; see section C for a classification of the ZMB type material. Phylogenetic analyses For several decades now two hypotheses have been discussed as to the classification reflecting phylogenetic relationships of the two aplacophoran taxa, Solenogastres (or neomenioids) and # 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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