A list of all 4404 described species and subspecies of Recent and Subrecent Mollusca recorded from the New Zealand Exclusive Economic Zone (EEZ) is given. Each entry is substantiated by a bibliographic reference for the record and its most recent nomenclatural combination. An approximate geographical range is also given for each species. Both endemic and adventive species are identified.

Keywords: New Zealand, Mollusca, molluscs, mollusc, mollusks, mollusk, checklist, taxonomy, biodiversity, fauna, bibliography.

In 1913 Henry Suter published his Manual of the New Zealand Mollusca, ushering in a century of research on New Zealand's molluscan taxonomy. As a result of this work, when the first edition of A.W.B. (Baden) Powell's The Shellfish of New Zealand appeared some 24 years later, the New Zealand checklist was vastly different from any which might have been compiled in Suter's time. Many of the species' names had changed unrecognisably, and a large number of new species had been described. Through the various editions of Powell's checklist (1937, 1946, 1957, 1962, 1976), both amateurs and professionals with interests in New Zealand's molluscs had been able to keep track of the taxonomic changes. The names used in the fifth of Powell's checklists correspond almost exactly to those appearing in his magnum opus, New Zealand Mollusca: Marine, Land and Freshwater Shells (even though this work was not published until 1979 [Willan 1981]).

Powell's manual, like Suter's before it, and as Powell himself hoped in his Preface, stimulated a renewed interest in New Zealand's molluscan fauna. One almost inevitable consequence of the taxonomic study, however, is a constant changing of the names of species even very familiar ones together with a steady flow of new species. As a result, the New Zealand checklist is now substantially different from Powell's final one. This present checklist is designed to supersede Powell's, allowing both professionals who work with (as opposed to on) molluscs (e.g., sedimentologists, marine ecologists and others who "just want the name") and amateurs alike to find and use the name that specialists now consider correct.

The taxonomy in Powell's (1979) manual has been our starting point, so all the species in our list that are mentioned there (i.e., the vast majority) have a reference to the appropriate page in the manual. All those species newly discovered in, or described from, New Zealand between 1973 and 2003 are fully referenced. Similarly, a reference is included for specific name changes and changes in generic location.

As compilers, we have had to make several editorial decisions in the course of assembling the checklist. We have been conscious of the need for objectivity and therefore scrupulous in following the latest taxonomy at the level of genus and species, even though we do not always agree with it and expect further changes with future research. We consider changes are the province of specialists in particular groups who can offer substantive arguments for the changes they recommend. A few exceptions arise because we have followed the regulations in the ICZN code regarding agreement (of gender) between genus and species. These policies mean that parts of the checklist will continue to show nomenclatural instability, but such instability can be considered as a byproduct of ongoing research.

Our checklist covers all marine and non-marine molluscs from the New Zealand Exclusive Economic Zone (EEZ). Powell (1979) followed Suter (1913) in separately listing the introduced non-marine pulmonate species in an appendix. We have included them in our list because these molluscs now form an integral part of the New Zealand fauna. Moreover, we include taxa from the Kermadec Islands, which are part of the EEZ.

In contrast, we have decided to exclude tropical Indo-Pacific species (e.g., Stomatia phymotis Helbling, Cribrarula cribraria Linnaeus, Polinices mammatus Röding, P.melanostomoides (Quoy & Gaimard), P. conicus (Lamarck), Chicoreus ramosus (Linnaeus), Rapana venosa Valenciennes, Latirus gibbulus (Gmelin), Phidiana indica (Bergh), Lopha cristagalli (Linnaeus), Chama pacifica Broderip, Nautilus macromphalus Sowerby, N. pompilius Linnaeus) and temperate Australian species (e.g., Eunaticina umbilicata (Quoy & Gaimard), Fusinus novaehollandiae (Reeve)) recorded from New Zealand on the basis of very few specimens because they probably result from the metamorphosis of chance teleplanic larvae in New Zealand waters. There is no evidence that such species have established breeding populations in this country. Neither have we included fossil species, for which admirable checklists already exist (Fleming, 1966; Beu and Maxwell, 1989).

Format of checklist

The format of our checklist follows that of Powell's, especially the latter ones (Powell, 1962, 1976). A typical entry can be used to explain the conventions we have used:

MARGINELLIDAE: MARGINELLINAE

• Mesoginella Laseron, 1957 (Marginella turbinata G.B. Sowerby II) (= Sinuginella Laseron) (Cv2. 86)

• koma B.A. Marshall, 2004 (= pygmaea of authors not G.B. Sowerby II) (P1. 220; Mr51. 14) A.E.

This example shows that the species known as Mesoginella koma belongs in the genus Mesoginella, a member of the subfamily Marginellinae in the family Marginellidae. The species was named by B. Marshall in 2004 in the genus Mesoginella; if it had been erected in another genus the author’s name and date would be in parentheses. It has previously been known under the name Mesoginella pygmaea in several works, but it is not the species described by G.B. Sowerby II. The species is described in Powell's (1979) manual on page 220 (coded as P1. 220 in our checklist) and Mr51 on page 14 (coded as Mr51. 14), where the latest taxonomic placement is justified. Laseron erected the genus Mesoginella in 1957 and the type species of this genus is Marginella turbinata, described by G.B. Sowerby II. Current scientific opinion (given in reference Cv2. 86) holds that Laseron’s genus Sinuginella is a junior synonym of Mesoginella.

Bibliographic codes

The bibliographic codes (such as P1. 220) are the abbreviations for the references in the Bibliography, which can be accessed by clicking on the code. They will appear in the frame at the bottom right of the screen.

Geographic codes

The geographical range of each marine taxon is indicated by the codes K. A., C., F., M., and An. These symbols denote Powell's New Zealand zoogeographical provinces, with the addition of K. for the Kermadec Islands, and are defined in the table below. Although the concept of zoogeographical provinces has severe limitations (especially when applied to deep water species), these symbols do give some approximation of the geographical range of a species. An E denotes an endemic species and an I an adventive (introduced) form. Species inhabiting freshwater habitats are indicated by the abbreviation FW, and landsnails by L; their ranges are denoted by N for the North Island and S for the South Island, and other islands by standard abbreviations. Mesoginella koma is thus found around the north-eastern coast of the North, Island and is endemic to the New Zealand EEZ.

Number of species

The number of described species and subspecies on the New Zealand list is currently 5,486, distributed among the classes as follows.

These numbers are clearly an underestimate of the number of biological species present. We estimate nearly 1700 species have been collected yet await formal description (and, of course, an unknowable number have yet to be discovered) (Spencer et al. 2009).

Acknowledgments

This work would have been impossible without the assistance of many people. Dennis P. Gordon inspired us to update a previous list (Spencer and Willan 1996). C.C. Lu and Steve O'Shea assisted with the complexities of cephalopod taxonomy. Staff at the Science Library, University of Otago were particularly helpful in tracking down obscure references and obtaining inter-library loans, and Fiona Stuart carried out much of the latest web-page revisions. Of course, as authors, we remain solely responsible for the errors and omissions which (in spite of every effort) will have crept into this work. We would be most grateful if these mistakes could be pointed out to us, so that corrections can be incorporated in a updated versions of this page, which we hope to revise annually. Financial support was generously provided by the Division of Sciences, University of Otago.

References Cited in Introduction

Beu, A.G.; Maxwell, P.A. 1990: Cenozoic Mollusca of New Zealand. New Zealand Geological Survey Palaeontological Bulletin 58. 518 pp.

Fleming, C.A. 1966: Marwick's Illustrations of New Zealand Shells with a Checklist of New Zealand Cenozoic Mollusca. New Zealand Department of Scientific and Industrial Research, Bulletin 173. 456 pp.

Powell, A.W.B. 1937: The Shellfish of New Zealand. 1st ed. Unity Press, Auckland. 100 pp.

Powell, A.W.B. 1946: The Shellfish of New Zealand. 2nd ed. Whitcombe and Tombs, Auckland. 106 pp.

Powell, A.W.B. 1957: Shells of New Zealand. 3rd ed. Whitcombe and Tombs, Auckland. 202 pp.

Powell, A.W.B. 1962: Shells of New Zealand. 4th ed. Whitcombe and Tombs, Auckland. 203 pp.

Powell, A.W.B. 1976: Shells of New Zealand. 5th ed. Whitcoulls, Auckland. 154 pp.

Powell, A.W.B. 1979: The New Zealand Mollusca: Marine Land and Freshwater Shells. Collins, Auckland. 500 pp.

Spencer, H.G.; Marshall, B.A.; Maxwell, P.A.; Grant-Mackie, J.A.; Stilwell, J.D.; Willan, R.C.; Campbell, H.J.; Crampton, J.S. 2009. Phylum Mollusca – Chitons, clams, tusk shells, snails, squids and kin. In press in: D.P. Gordon (ed.) The New Zealand Inventory of Biodiversity. Volume 1. Kingdom Animalia: Radiata, Lophotrochozoa and Deuterostomia. Canterbury University Press, Christchurch.

Spencer, H.G.; Willan, R.C. 1996. The Marine Fauna of New Zealand: Index to the Fauna 3: Mollusca. New Zealand Oceanographic Institute Memoir 105.  NIWA, Wellington.125 pp.

Suter, H. 1913. Manual of the New Zealand Mollusca. Government Printer, Wellington. 1120 pp.

Willan, R.C. 1981: Bibliography of publications of New Zealand Mollusca (1973-1980). Miscellaneous Publication New Zealand Oceanographic Institute 94. 50 pp.

Last modified: May 2017