VOL. 9. PART 1. JUNE 1977* CONCHOLOGY SECTION AUCKLAND INSTITUTE & MUSEUM . POIRIERIA Vol 9 Part 1 June 1977 JALCIS ( PICTOBALCIS ) APTICULATA (Sowerby) While the shells of our small, very slender species of the genus Bale is are invariably white - sometimes porcellanous and sometimes glossy - we seem to have gained fairly recently a species which is delightfully different. This is Pictobalcis articulata ., first recorded from New South Wales, and now not infrequently collected in beach drifts from Cape Maria .to at least as far South as Whangaruru. The first examples recorded in New Zealand were collected in 1971. The subgenus was apparently erected to contain those species which sport a colour pattern, and articulata has a very pleasing one - a central band of chestnut from which narrow chevrons extend from both sides , reaching almost to the sutures, Size of Cape Maria specimen. ' while from each varix runs a vertical stripe on the base of the shell. Ground colour is porcellanous white. The largest examples I have seen came from Cape Maria van Diemen and measured just over '30mm x which is considerably larger than the type specimen from Australia. The molluscs belonging to this genus are parasitic - mostly on echinoderms, but v;e dOj in fact, know very little about the hosts of our own New Zealand. species , most of which are no more than 5 or 6 ram in length. * * * * * A NOTE ON DREDGING OFF TOLAGA BAY R, M. Lee On a recent dredging trip off Tolaga Bay, where I live, I hopefully tried a- new location about four miles offshore in 26 - 28 fathoms on mud and sand bottom. Results, however, were very poor, with only two small valves of Neilo australis , one Proxiuber and a bit of shingle to show for my trouble. So, after being almost run over by the vessel UNION MELBOURNE, I decided to try one of my old stations where previously I have had considerable success. This is about three-quarters of a mile offshore in a sand channel between hard rock and Bryozoan bottom in 15 to 18 fathoms. On my first try I missed the sand and ended up in the rocks, so up came the dredge again and a move of a few yards was made. The second time was a success and I dredged for about 200 yards before hitting rock. Now there was a fair weight in the dredge and up came one of my best hauls. 1 Aeneator compta 10 Corainella ISIS 2 Monodilepas monilifera 3 Maurea osbornei:®* cookiana About 50 Cylichna thetids 4 Poirieria zelandica 1 Herpetopoma laochei Liratilia conquista 1 Odostomia acutangula Marginella raustelina 8 Phenatoma novaezelandiae Axyraene aucklandicus and 1 P.zealandica 4 Aoteadrilla wanganuiensis 1 Gari lineolata (alive) wanganuiensis 3 Buccinulum colensoi and several Tellinella h.huttoni, T.h.sterrha, Neoguraleus amoenus, Scalporaactra scalpellum., Linucula gallinacea. Myadora boltoni (alive) and many more, naking in all 53 species that I have identified. The majority of the gastropods were dead and housing hermit crabs, while the bivalves were alive. This seems to be the rule in this area. 'The closer I can get to rough bottom, the better the results, too. - 2 - ) ) THE LAND MOLLUSCA OF MT WELLINGTON LAVA FIELDS - TODAY and YESTERDAY N.W.G. Those whose interest lies in our small native land snails will have, no doubt, often read in Suters Manual the locality record "Mt Wellington lava fields". Little thought is now given to that area, but Henry Suter spent quite a time collecting there before writing his Manual in 1913} and a fair number of species are listed by him. But what of the area today? While, no doubt, quite extensive in Suter 's time - possibly extending from Mt Wellington to Penrose and with a fair coverage of native vegetation - this rugged terrain of piled scoria blocks and pits has now been drastically reduced to fill the needs of housing and industry. Now only a small remnant remains, as far as v/e can determine, at the end of Herbert Road, Mt Wellington. Although only a few acres in extent, the vegetation is dominated by various introduced plants, with only a few natives persisting down in damper scoria pits below the general ground level. Small Titoki and Karaka and some Pigeon-wood were noted. Astelia and ferns were more prevalent - possibly this remnant has been burnt over at times as no trees of any size were seen. Seventeen species of small land snails were recorded from Mt Wellington by Suter in his Manual and these are listed below: Thalassohelix ziczag (Gould) Charopa angiculus (Reeve) Therasia celinde (Gray) Charopa buccinella (Reeve) Therasia tamora (Huttqn) Laoma marina (Hutton) Phenacohelix ponsonbyi (Suter) Laoma conella (Pfr. (type locality) Laoma erigone (Gray) Flammulina chiron (Gray) Laoma glabriusculus (Pfr.) Flammulina pilsbryi (Suter) • Laoma moellendorffi . (Suter Ptychodon tau (Pfr.) Paralaoma lateumbilicata (Suter) Paralaoma pumila (Hutton) Such an assemblage of species suggests a reasonably heavily wooded area. The following species are existing at the present time in this small area of much modified ground cover, and usually under scoria blocks or where a small amount of leaf litter has gathered between them. Most of these records are those of J. Goulstone, supplemented by the results of a field trip by the Conchology Section in September 1976. -3 - Liarea egea (Gray) 2 . Subfectola caputspinulae Cytora cytora (Gray) (Reeve) 4 Laoraa leimonias (Gray) 2 Thalassohelix zelandiae 9 Laoma (Phrixgnathus) erigone Suteria ide (Gray) 3 (Gray) 3 Phenacohelix given! Cumber Laoma (Phrixgnathus) moellendorf 25 fi (Suter) 2 Phenacohelix pilula (Reeve) 1 Laoma (Phrixgnathus) sublucidus Therasiella celinde (Gray) 1 (Suter) 4 Char 0 pa coma (Gray) 2 Laoma (Phrixgnathus) transitans (Suter) Mocella eta (Pfr.) 2 Paralaoma lateumbilicata(Suter 1 Ptychodon pseudoleioda ) (Suter) 2 Delos coresia (Gray) 1 Ptychodon tau (Pfr.) 1 Tornatellinops novoseelandica (Pfr.) 2 THE BRACHIOPQDS OF STEWART ISLAND R. C. ’A'illan I make no apologies for giving this title to an account of the molluscs I collected at Stewart Island because it v/as only through a brachiopod survey funded by National Geographic Magazine that I was able to visit Stewart Island in February 1977. So 1*11 give the brachiopods their due by mentioning them in the title and then net xiiscuss them further here because theirs is a separate story. I had as company on the Paterson Island Expedition an assorted bunch of Australian and New Zealand marine biologists and oceanographers - as good company and entertainment as one could hope to find anywhere. Our floating home for eight days was R.V. ACHERON and on board the accommodation was five star standard, so excellent that one of the party quoted "Acheron Hotel** when asked where he had made his airline reservations. ACHERON is skippered by Captain Alex Black, a name no doubt familiar to shell collectors from his ALERT days and honoured in such molluscan combinations as Alertalex black! , Maurea black! , Laoma black! and Cominella alertae . The entire survey was done at Paterson Inlet, that very large harbour that is sliced out of the north eastern side of Stewart Island and serves as the focus of life for all Stewart Islanders. We came to know the inlet with its bush-fringed bays and islands very well during this expedition because the programme called for a survey of as many different sites as - 4 - possible. And survey we did, by dredging and diving we worked 38 stations extending from tho eastern side of Native Island and Anglem Point at the entrance back to North Arm and South West Arm located near to the hilly, forest-covered centre of Stewart Island. Besides accommodation, ACHERON'S next attribute is its dredge - the most efficient I have seen in use. In combination with the Captain’s knowledge, a tow of only one and a half minute's bottom time always came up full of material, so full in fact that it was sometimes necessary to literally shovel part of the haul overboard to enable us to find the sorting . table so that we could wash and search through- the rest. , Stations worked on muddy bottoms such as at the entrance to South West Bay (= Big Glory Cove) and in Glory Cove itself were probably the most rev/arding in molluscan terms. Diving was difficult in these areas because of the clouds of sediment stirred up as we worked, the lack of current to remove this sediment and also because most of the molluscs were buried anyway. Where there is limited mud brachiopods dominate, in muddier areas both brachiopods and Chlamys gemmulata suteri occur commonly together, but a touch more silt tilts the balance to the Chlamys ’ favour and in the upper reaches even Chlamys does not occur. Other molluscs living in these muddy habitats were Cominella nassoides nassoides , Buccinulum pertinax pertinax , Glaphyrina sp. , Monodilepas monilifera monilifera , Euthrenopsis otagoensis , Uberella vitrea , Pleurobranchaea maculata , Diplodonta rakiura , Maorikellia rotunda , Cuspidaria trailli , Tellinella huttoni , Thyasira resupina m ozelanica , Anthochiton canaliculata and Craspedochiton rubiginosus . Areas in v/hich silt is removed by currents to leave a sandier bottom were found to be best sampled by diving. Some such areas are the channel off the eastern tip of Ulva Island, northern side of Ulva Island and northern side of Native Island. Here there is a less spectacular assemblage dominated by Tawera spissa and Pec ten novae - zelandiae rakiura , with other less numerous molluscs being Nemocardium o ulchellum , Gari lineolata , Notocorbula zelandica , Thracia vitrea , Atrina pec tinata zelandica and Alcithoe swainsoni . Dead bivalve shells with large drill holes were conspicuous everywhere; at first I accused Tanea zelandica of this predation, but I later observed the real culprit in action - Xyrne ne ambiguus .