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Tuatara is a medium for presenting the methods and results of biological research in a form acceptable to students at secondary schools as well as at the university. It is a tangible link between the university and its future students. Over the past fourteen years leading scientists have cooperated by contributing articles on topics in which they have special knowledge, and many students, some of them now professional biologists in New Zealand and abroad, have seen their first work published in this journal. The editor will welcome guidance from teachers in secondary schools as to topics which they would like to see covered in future issues. For example, one secondary school in a country district has sought information on the general anatomy of the opossum, which is used there as a subject for dissection; an authority in this field is now preparing an article which we hope to publish shortly. Other contributions in forthcoming issues will include an illustrated key to all New Zealand butterflies, anatomical guides to the New Zealand lugworm Abarenicola and the freshwater mussel Hyridella, and Dr.
If all organisms were pelagic their distributional patterns would more or less correlate with the physical factors of water, temperature, ocean currents, and prevailing winds.
However, the fact that many organisms lack or have poorly-developed free-swimming larvae introduces a percedure of stenozonal species or sub-species, and the presence of these to a marked degree gives rise to the necessity of subdividing regiob or sub-regions into provinces.
A past or present topographic barrier often service as a segregating influence but such barriers are not essential, for more distance is often sufficient to outrange the distributing powers of many stenozonal
A province may be defined as an area within a faunal region that exhibits a marked percentage of endemism.
Published proposals for the subdivision of the Maorian Sub-region are as follows:
All the provinces so far nominated for New Zealand apply to the intertidal zones plus the shelf. The pelagic elements have been noted, but more or less as influences only.
When faunas from the deeper waters are better known it will almost certainly be found that provinces are fewer, more extensive, and bear little or no resemblance to the inshore ones.
We may therefore have to consider the problem as three-dimensional, i.e., (1) broad oceanic areas for pelagic faunas; (2) inshore and shelf faunas; (3) deep sea faunas (probably divisible into several levels).
In 1925 (Verbeek Birthday Volume) Dr.
In 1926 (Trans. Roy. Soc.) Finlay added the proviso that the Cookian and Forsterian may not be natural as previously defined and suggested that in the event of readjustments these names apply to the southern portion respectively of each island.
In 1937 (Discovery Reports) I contributed a further province, the Aupourian, and suggested more precise boundaries for the Cookian and Forsterian. These were:
In 1940 (Trans. Roy. Soc. N.Z.) I adhered to my previous definition of the Aupourian and stressed the strong representation of the Peronian, that is the New South Wales element, in the fauna.
In 1944 Aupourian: Within the Subtropical Zone of surface water. Cookian: Mixed waters of middle region of New Zealand. Moriorian: Isolation and mixed waters. Forsterian: Isolation plus predominant Subantarctic waters. Rossian: Entirely within the Subantarctic Zone of surface waters, plus isolation.(Trans. Roy. Soc. N.Z.) Fleming defined the provinces in general terms, but did not give precise boundaries. He linked the provinces with physical factors as follows:
In 1951 (Discovery Reports, Vol. 26, p. 67) I advocated dropping the name Rossian Province and substituting a prior name of Waite, 1916, the Antipodean (i.e. Antipodes District) for the Subantarctic Islands of New Zealand, including Macquarie Island, Stewart Island and Southern Otago.
In 1949 (Report of the Sixth Science Congress, Royal Society of New Zealand, Vol. 76. part 5) Miss The Marine Algal Provinces of New Zealand, Miss Moore remarked that “It is not yet clear whether the equivalent of Powell's Aupourian Province can be recognised for the marine algae, but if so it would extend at least as far as Bay of Islands and Poor Knights, and would then include some 14 species not otherwise known on the New Zealand mainland.'
In 1952 (N.Z. Geological Survey Pal. Bulletin 18, p. 16) Mr. N. de B. Hornibrook in monographing New Zealand Tertiary and Recent Marine Ostracoda quotes me (correspondence) as follows: “I have recently gathered good evidence for extending the Aupourian to as far as East Cape, but on the West Coast it does not seem to reach below Ahipara.’
In my “Mollusca of the Southern Islands of New Zealand’, Forsterian: Snares Island, Stewart Island and Otago. Antipodean: Antipodes, Bounty, Auckland and Campbell Islands. Kerguelenian: Macquarie Island, Kerguelen, Heard Island, Marion Island, Prince Edward Island and Crozets.Cape Expedition Series, Bull. 15. pp. 6, 7, I proposed a re-orientation of the Antipodean (Rossian of Finlay) as follows:
Since this was written, Fleming (1951) published a bathymetric chart of the area which is in harmony with the above independently-reached conclusions. I note that Fell also (1953) in his Echinoderms from the Subantarctic Islands of New Zealand separates the Snares fauna from that of the other southern islands, and places it in the Forsterian.
I note also that Dell in the N.Z. Oceanographic Committee's O.R. 82 reports the finding of many species of mollusca previously recorded only from off the Snares Islands, in the Chatham Islands expedition Station 34, from 130 fathoms east of the Chathams. This is relevant to my forecast that provinces may be fewer and more extensive in the deeper waters. Before treating the New Zealand
Dr. Dell contributed an excellent paper on the molluscan fauna of this province to the Eighth Pacific Science Congress (not yet published) in which he considered the Kermadec fauna to be an outlying sub-region of the Indo-West Pacific of equal value to the Philippian for Lord Howe Island and the Montrouzierian for New Caledonia.
This province is characterised by a large percentage of Peronian organisms which have obviously reached here through the agency of the East Australian or Notonectian warm water current and subtropical or approaching subtropical conditions have enabled them to stay.
The molluscs include several species of the Cymatiidae, Agnewia tritoniformis, Xenogalea pyrum and labiatum, Tolema and Emozamia. The echinoids are represented by the fire-brick starfish Asterodiscus and the crustacea by the frog crab Lyreidus. Some of the exotic genera that have reached here by means of the Notomectian current have since developed as local sub-species.
After ignoring the relatively constant influx of Peronian and other wide-ranging species, some of the characteristic elements of the Aupourian are:
The carrier shell, Xenophora neozelancia, Tonna haurakiensis, Pteronotus eos, Gomphina maorum, Alcithoe depressa, Venericardia reinga, Haliotis virginea crispata, the large heart-urchin, Brissus gigas, and the brachiopod, Terebratella haurakiensis.
Evidence of the former cold phase in the Aupourian is exhibited by the presence of the Subantarctic bivalve molluscan genera Gaimardia, Kidderia and Costokidderia. The presence of the giant kelp, d'Urvillea, the Cookian limpet, Cellana denticulata, and a record of the Forsterian Cymatid mollusca, Fusitriton laudandum, may be related to prevailing south-west wind and the upwelling cold water on the west coast under present conditions.
It should be pointed out also that the configuration of the Northland west coast results in the prevailing south-west wind operating on-shore in the north but off-shore in the south.
It is worthy of note in regard to the extra limital distribution of Cellana denticulata that its northern occurrences are invariably on off-shore islands or on strongly projecting land features. It suggests that point-to-point distances may be achieved within the time factor in situations where strong tidal currents operate, but that the larval free-swimming period is not sufficiently long to enable a more thorough dispersal into the embayed sections of the coastline.
A review of the evidence now suggests more positive boundaries for the Aupourian. All interests seem to be in agreement that the eastern boundary should be the East Cape. The western boundary is not so clearly indicated, due to the conflicting effects of the Notonectian warm water current, upwelling cold water and prevailing south-west winds, but a division of some elasticity is indicated as occurring between Reef Point, Ahipara and Manukau Heads.
Recent records of Zeacolpus ahiparana from Manukau Heads and Tonna haurakiensis from off Maunganui Bluff support this contention.
The Cookian as pointed out by Fleming (1944) occupies the middle region and is largely in a belt of mixed waters with both subtropical and subantarctic influences.
The northern boundaries seem reasonable in relation to those fixed for the southern boundary of the Aupourian. The southern boundaries for the Cookian can be conveniently fixed as far as the littoral is concerned by the buffer zones represented by long shingle beaches on each coast, with impoverished fauna that separate the Cookian from the Forsterian. That these boundaries do not apply so rigidly for the shelf fauna is clearly shown by occurrences of warm water genera trawled both off Timaru and off Greymouth. The species instanced are Galeodea triganceae recently described by Dr. Dell and the northern Ranella multinodosa.
The Cookian as at present constituted is complicated by the assumed comparatively recent formation of Cook Strait and the evidence of a middle Pliocene division between the islands, approximately between Wanganui and Napier.
Some of the characteristic Cookian stenozonals are Verconella ormesi, Cellana denticulata, Thoristella chathamensis cookiana and Buccinulum colensoi. which ranges from the Wellington east coast to East Cape.
The Forsterian is a well defined province including the whole of Otago and Stewart Island. I have in my report on the Cape Expedition extended the province to take in the Snares Islands, which are situated on the South Island shelf. The molluscan fauna of the Snares is clearly Forsterian rather than Antipodean (= Rossian).
It is worthy of note that Dr. Fell in his latest paper (1953). Echinoderms from the Subantarctic Islands of New Zealand, also considers the Snares fauna to be essentially Forsterian.
The most characteristic species of the Forsterian is the limpet Cellana redimiculum. The subantarctic influence is, as would be expected, more marked than in the Cookian. The genera involved are Gaimardia, Kidderia, Costokidderia, Margarella and Kerguelenella.
The occurrence in the estuarine waters of the Manukau Harbour of a mollusc simulating if not identical with the common Forsterian coast Maurea punctulata stewartiana is puzzling. Since the stations are different one explanation is that the Manukau occurrence merely represents an ecological variation of the common northern typical species.
However, another possibility occurs to me after hearing a paper by Drs. Habe, Kuroda and Miyadi at the Eighth Pacific Science Congress, entitled Some Problems on Marine Biogeographical Micro-Provinces surrounding Japan. These authors point out that in southern Japan cold water continental coastal fauna elements often survive in harbours, whereas the adjacent open coast may have a warm water fauna belonging to a different marine province.
The Manukau Maurea may therefore be a relic from a past colder climatic phase when the Forsterian elements would presumably have extended much further north.
We have such evidence in the Nukumaruan North Island occurrences of the scallop Chlamys delicatulus, which at present does not seem to occur alive north of Otago Peninsula.
A recent finding of two examples of the brachiopod Neothyris lenticularis in 80 fathoms off East Cape may represent another survival of an at present otherwise restricted Forsterian element.
The percentage of species or sub-species restricted to the Forsterian is quite considerable.
This is the name which I contend should replace Finlay's Rossian from which I exclude the Snares as already mentioned, and also Macquarie Island, which I place in the Kerguelenian.
This province lies entirely within the Subantarctic Zone of surface waters. The fauna is an impoverished one, including only the most tolerant of the mainland genera with a liberal sprinkling of the characteristic subantarctic genera: Patinigera, Pareuthria, Margarella, Kerguelenella and Plaxiphora
Endemism is high with both elements in the fauna.
In my report on the Cape Mollusca I advocate segregating Macquarie Island from the Antipodean on the evidence of the inclusion in the fauna of a number of stenozonal truly subantarctic genera that do not occur in the other New Zealand subantarctic islands, i.e. Falsilunatia, Puncturella typical, Trophon typical, Prosipho, Admete, and Lima pygmaea.
That Macquarie Island was formerly more closely linked with the New Zealand shelf is indicated by the presence of Tawera, Chlamys
delicatulus, a Maurea of the spectabile group, Plumbelenchus, and the limpets Notoacmea pileopsis sturnus, and Actinoleuca
The presence of the genus Cymatona, known elsewhere only from the East Australian Continental shelf is a surprise element in the Macquarie fauna.
The Moriorian was nominated for the Chatham Islands fauna, which has a considerable percentage of endemic sub-species and shows strong northern and southern influences in almost equal amounts, as one would expect from the situation of the group.
An estimate of the number of marine species in each of the six New Zealand faunal provinces is as follows:
Since the above was written Dr. Dell (1960, Biological Results of the Chatham Islands 1954 Expedition. Part 4, D.S.I.R. Bull. 139 (4) has evaluated the Moriorian Fauna in the light of the very considerable recent additions he has made to the fauna (see also Dell, 1956. The Archibenthal Mollusea of New Zealand, Domin. Mus. Bull. No. 18).
The result of Dr. Dell's survey emphasises the distinctive character of the Moriorian but arrives at more precise conclusions regarding the relationship of the fauna in respect to mainland provinces. He gives a total of 320 species, of which 204 occur also in the Cook Strait area, 6 are pelagic and 49 are endemic. Only 13 are confined elsewhere in the north while 38 occur in the south with 5 in the subantarctic islands.
The Moriorian remains well defined not only by the high percentage of endemic species (15.3%) but also by the number of common widespread mainland species that are not represented — i.e. Mytilus canaliculus, Mactra discors, Spisula aequilateralis, Dosinia anus, lambata and subrosea, Dosinula, Notocallista, Myadora striata, Scutus, Lunella smaragda, Struthiolaria, Baryspira, Alcithoe, Benhamina and a number of others.
Those interested in antarctic marine faunas are referred to a recently published paper (Powell, 1960, Antarctic and Subantarctic Mollusca, Rec. Auck. Inst. Mus., Vol. 5 (3-4), pp. 117-93).
The faunal characteristics of the antarctic and subantarctic areas, as well as the physical factors involved, of ocean currents, antarctic and subtropical convergences, effects of upwelling cold water, submarine ridges and deep-water basins are all discussed.
That faunal divisions based upon shallow-water faunas do not necessarily apply to the Archibenthal and deeper waters is evidenced by some previously considered anomalous distributional patterns.
For instance it is shown in the case of Pontiothauma, a genus of Turrids known from Bay of Bengal, off Java and Enderby Land, Antarctica, in deep water, that they follow the northward flowing antarctic cold heavy water along the bed of the deep ocean basins and the same applies regarding the arctic-antarctic continuity of another Turrid genus, Aforia, which goes deep over the tropical zone and is otherwise assisted in its temperature requirements by upwelling along its west American distributional route.
During a recent (May, 1961) dredging expedition (Govt. Research Trawler “Ikatere’) along the shelf of the Northland east coast several molluscs were obtained at 150-240 fathoms that were previously known only from the Archibenthal of eastern Otago. i.e. Parvamussium maoria Dell. 1956.
Echinoderms appear to be particularly suitable as material for the study of patterns of distribution, owing to their relatively sedentary habits, their aversion to fresh or even brackish water, the brevity or complete absence of a pelagic larval life, and their usually short bathymetric range.
This article deals mainly with patterns of distribution of the shelf fauna, that is, species known to depths of 100 fathoms. The archibenthal and abyssal faunas will also be considered.
Marine Provinces have been defined by Finlay (1925) and Powell (1937) on the basis of Mollusca, and have also been applied to the shelf echinoderms (Fell, 1949, and later references). In this paper an attempt is made to find correlations between the very restricted distribution of some species and physical environmental factors. It would be useful indeed if we could say that some one marine province is bounded to the north by an ocean current and to the south by another current or trench, but with the present state of our knowledge no really definite statements such as this can be made.
The boundaries of the provinces as suggested by the known echinoderms of New Zealand may be at variance with the boundaries indicated by other animal groups, e.g. Mollusca, but this is possibly due to many factors, among them differences in powers of locomotion, mode of reproduction, and others. Probably the most important factor is our lack of a more complete knowledge of the patterns of distribution of the animals concerned.
Of the New Zealand shelf echinoderms, approximately 59% have a scattered distribution pattern, and show no clear provincial pattern. The remaining 41% appear to conform rather well to the provincial system, and may be separated into groups, each group being restricted to a province and typical of that province.
The Kermadec Islands are often excluded from the New Zealand region as they are truly subtropical in position and in the general affinities of their fauna. At first sight the echinoderm fauna of these islands seems to show a generalised Indo-Pacific facies; of the 13 recorded species 6 (46%) are Australian-Indo-Pacific, 5 (39%) are restricted to the Kermadecs, and only 2 (15%) are shared with
Closer analysis of the echinoderm fauna, however, leads to a different conclusion. One of the restricted species, Patiriella oliveri, is very closely related to Patiriella regularis of the New Zealand mainland, and the two almost certainly share a common ancestry. Another starfish restricted to the Kermadecs, Astrostole rodolphi, is very closely related to Astrostole scabra of the New Zealand mainland.
Of the two species shared with New Zealand, Ophidiaster kermadecensis ranges the Bay of Plenty and the Kermadecs and is unknown elsewhere in the world. The other is Evechinus chloroticus ranging the entire New Zealand mainland and, apart from the Kermadecs, unknown elsewhere in the world; Evechinus is known fossil in New Zealand, at least from the Pliocene (Nukumaruan). Of the Australian-Indo-Pacific species, Astropecten polyacanthus is also shared with the Aupourian Province of New Zealand.
There is, therefore, good echinoderm evidence for including these islands in the New Zealand region, possibly as a sub-region of the Aupourian Province, but more collecting is obviously required.
The Aupourian Province was established for Mollusca to cover Three Kings Islands and all that part of the North Auckland Peninsula above Ahipara on the west and Whangaroa on the east coast (Powell, 1937). It was known then that the province was distinguished by the presence of a number of subtropical molluscs. Powell (1955) subsequently extended the south-eastern boundary of the province to East Cape, and Fell (1952) had found this to be consistent with the echinoderm evidence. So far as the echinoderms are concerned, the south-western boundary of the Aupourian Province cannot fall north of Cape Egmont (Fig. 1), as otherwise certain species with a distinct Australian-Indo-Pacific facies would present an anomalous distribution.
Some typical Aupourian echinoderms are Asterodiscus truncatus (Powell, 1937); Astropecten polyacanthus (known from as far south as New Plymouth to the west and East Cape to the east); Centro-stephanus rodgersii (from south of Whangaroa); Holopneustes inflatus (from Great Barrier Island); Clypeaster australasiae (off Parengarenga and East Cape) (Fell, 1949b). All of these species are also present in the Australian echinoderm fauna and are typical subtropical forms. Another species, Brissus gigas, from the Bay of Islands (Fell, 1947), is very closely related to a widespread Indo-Pacific species Brissus latecarinatus. At the present time, fifteen species may be named as typical of this province.
If the subtropical forms can only move as far south as Cape Egmont to the west and East Cape to the east, there must be some
Deacon (1937) suggested that the northern limit of the subtropical convergence to the west of the North Island lies at about 42° S. and 170° W. and strikes towards the coast in the neighbourhood of Cape Egmont. Garner (1959) noted a pronounced drop in the level of the mean surface temperature between the areas off Capes Egmont and Farewell, and thus tended to agree in part with Deacon's premise. We know that most of the subtropical species tend to be stenothermal, and thus Cape Egmont might form a southern boundary for the Aupourian echinoderms of the west coast. The cooler waters of the Westland Current (Fig. 1) flow past Cape Egmont at varying times throughout the year, but the northern limit of the current is variable (Brodie, 1960). The current, however, may play some part in the regulation of distribution on this coast.
To the east the situation is not the same. The northern limit of the subtropical convergence strikes not towards East Cape, but towards Castle Point, some 300 miles further south (Fig. 1) (Deacon, 1937; Garner, 1959). Therefore there should be nothing preventing Aupourian forms from dispersing at least as far south as Castle Point if we use this northern limit of the subtropical convergence as an eastern boundary. But there are two factors which may act to prevent dispersal past East Cape for many echinoderm species:
The Canterbury Current, a colder water current, moves northwards near the coast towards East Cape (Fig. 1). Garner (1959) noted a significant drop in water temperature off East Cape at latitude 37.5° S. (Fig. 1), indicating a localised coastal upwelling of colder water.
Taken together, these physical factors might form an excellent barrier. The shelf echinoderms between East Cape and Hawke Bay are unfortunately not very well known, but those of Hawke Bay have been intensively studied in recent years, and no “strays from the north’ have been encountered as yet among the thousands of specimens taken from that region.
Probably the most important feature of the Cookian Province is the fact that it is an area of mixed waters, the site of the subtropical convergence (Fleming. 1944), and thus it is to be expected that its echinoderm fauna is of mixed composition. This was demonstrated by Fell (1949a). The Cookian Province seems to present a broad section of the New Zealand echinoderm fauna as a whole.
For the echinoderms the northern boundaries of the Cookian Province appear to lie at East Cape and Cape Egmont. The southern
Carpophyllum, Macrocystis). The west wind drift (Fig. 1) has a direct effect on the coastal current patterns in this area (Knox. 1960) and the occurrence of Magellanic elements in the Cookian Province is not so very surprising.
The Chatham Islands comprise the Moriorian Province in Finlay's (1925) scheme. These islands lie within the subantarctic mixed water zone and sit astride the subtropical convergence (Knox, 1960). For many other plant and animal groups the distinctiveness of this province lies in the mixed nature of its fauna, which usually contains northern and southern mainland forms, together with elements from the Antipodean Province and a number of forms with restricted distribution patterns.
The echinoderm fauna, Asteroidea, Ophiuroidea, Echinoidea (Fell, 1960) and Holothuroidea (Pawson, 1961) of the Chatham Islands is a mixed fauna in deeper waters, but the shelf fauna shows some remarkable features. The recent (1954) expedition to the Chathams greatly augmented our knowledge of the echinoderm fauna of that island group, and at the present time 56 species are known, 24 of which have been taken from depths less than 100 fathoms. Of these 24 shelf species. 8 (33%) are recorded from the Chathams, the Chatham Rise, and the New Zealand mainland shelf (especially in the Cook Strait region). Two species (8%), Henricia lukinsii and Calvasterias suteri, are also known in the Antipodean fauna, and clearly show a west-wind-drift distribution pattern. One species (4%) is circum-polar. The remaining 13 species (55%) are recorded from off the New Zealand coast, and are particularly well known in the Cook Strait area, but have not as yet been taken from the Chatham Rise. At the present time no shelf echinoderms appear to be restricted to the Chathams. In other words no species may be stated as being ‘typical’ of a Moriorian Province. On the basis of this evidence, then, there appear to be no grounds for giving to the Chathams the status of a marine province when the echinoderm fauna is considered. It must be indicated here that the echinoderm fauna of the Chatham Islands is still imperfectly known, but the facts as
The Forsterian Province is subject to the direct influence of the cold subantarctic waters of the west-wind-drift at certain times of the year and at others to the warmer mixed waters of the Southland Current. This province has some subantarctic affinities in its echinoderm fauna, and appears to form a transitional zone between the subantarctic cold temperate and the cold temperate mixed waters.
Echinoderms suggest that the Forsterian Province includes the southern portion of the South Island from Fiordland in the west and Dunedin in the east. Stewart Island and the Snares Islands. Fell (1953) gave reasons for regarding the Snares as part of the Forsterian Province, and Powell (1955, 1961) has confirmed this conclusion on the basis of Molluse. Of the four genera of echinoderms known to have species in the Snares, two are represented on the New Zealand mainland by identical species (Asterodon dilatatus and Stichaster australis) while the other two (Allostichaster insignis and Calvasterias suteri) occur both in the Antipodean Province and on the New Zealand mainland shelf. All Snares echinoderms which are shared with the other outlying islands are also shared with the New Zealand mainland. Thus, for the echinoderms the northern boundary of the Antipodean Province would fall south of the Snares (Fell, 1953). Support for this view is given by Knox (1961, personal communication), who reports Evechinus chloroticus from the Snares. It is interesting to note that the Snares lie on the shallow water plateau which extends southwards beyond Stewart Island. The 100-fathom line (Fig. 1) might suffice as the southern houndary for the Forsterian Province.
In general, the echinoderm fauna of the Forsterian Province resembles the Cookian fauna. Over 60 shelf echinoderms are known from this province. Of these, 6 (10%) are at this time regarded as typical Forsterian species. Subantarctic elements in the province include Trachythyone amokurae and Ocnus brevidentis.
The echinoderms of Fiordland include some forms which have distinct Australian-Indo-Pacific affinities. The presence of these forms in this part of the New Zealand region may be due to the influence of the East Australian Current, but as yet we have insufficient data. There are also northern New Zealand shallow-water species present in Fiordland, separated by a gap of about
Peronella binemoae and Amphiura alba. Another species. Amphiura hinemoae was formerly regarded as having a similar distribution pattern, but it was recently found to be an inhabitant of the abyssal zone, and thus, being a eurythermal species, its pattern of distribution is readily explained. It is possible that Amphiura alba and Peronella hinemoae may also be eurythermal species.
The Antipodean Province (formerly termed Rossian) is taken to comprise the Auckland Islands. Campbell Islands, Bounty Islands and Antipodes Islands. Macquarie Island does not stand on the New Zealand submarine plateau, and its shallow-water echinoderm tauna is strikingly different from that of the Antipodean Province island. The only New Zealand echinoderm in its fauna is Pseudechinus novae-zealandiae, which has a pelagic larva. Its presence in Macquarie Island is thus readily explained. Macquarie Island is therefore to be regarded as a member of the Kerguelenian (i.e. Subantarctic) Province.
The islands Auckland. Campbell, Bounty and Antipodes lie in a direct line with the west-wind-drift (Fig. 1), and it is to be expected that a certain percentage of their echinoderm fauna comprises circum-polar species. However, Mortensen (1925) clearly demonstrated that the bulk of the echinoderm fauna of the Auckland and Campbell Islands is of New Zealand derivation, not subantarctic, and Fell (1953) gave similar data for the Antipodes and Bounty Islands. An analysis of the known echinoderms of the Antipodean Province serves to demonstrate these relationships. Of the 27 known shelf species. 6 (22%) are restricted; 18 (66%) are common to the Antipodean Province and the New Zealand mainland, but are endemic to the New Zealand region as a whole; 2 (possibly 3) are circum-polar (8%), and 1 (4%) is cosmopolitan. There are no Australian-Indo-Pacific elements in the fauna as we know it today.
On the basis of the Asteroidea, Ophiuroidea and Echinoidea, Fell (1953) inferred that the echinoderm fauna of the Antipodean Province islands may have been derived from two sources, namely:
The greater part of the fauna has been derived from an assemblage of species which has been the common heritage of all parts of the New Zealand submarine plateau. This conclusion is based on the number of species which are common to the mainland and the islands of the Antipodean Province.
A small percentage of the fauna has possibly been derived from some originally southern species which have achieved a circumpolar distribution on account of their epiplanktonic habit (on brown seaweed), influenced by the west-wind-drift. In this way they could spread to other southern areas, such as Patagonia, Macquarie Island and Kerguelen Island, and subsequently
Amphiura magellanica, Calvasterias spp. and Pseudechinus spp. Similar conclusions may be drawn from the Holothuroidea (Pawson, 1961). It is interesting to note that the holothurian species Stereoderma leoninoides and Ocnus brevidentis, like the other echinoderms cited above, are known to inhabit the holdfasts of seaweeds in the eulittoral zone. The seaweed would form an excellent raft for dispersal, and the west-wind-drift the dispersal mechanism. Mortensen (1925) recorded two living specimens of Stereoderma leoninoides on a piece of floating Lessonia, one mile to the east of the Auckland Islands. This second source of contributions to the Antipodean Province fauna is of no great significance when the fauna as a whole is considered.
The term ‘Subantarctic Islands’ has been used by New Zealand writers to include the islands of the Antipodean Province, as well as Macquarie Island, Heard, Kerguelen, and many others. But whereas there is obviously a very close echinoderm faunal relationship between New Zealand and the Antipodean Province islands, the echinoderm faunas of the other islands mentioned are of a very different character, comprising mainly circum-polar species, together with some Antarctic genera. The echinoderm fauna of Auckland, Campbell, Antipodes and Bounty Islands is almost entirely New Zealand in character and is extremely dissimilar to that of the other islands under discussion. The two groups of islands are sharply distinguishable, the former belonging to the New Zealand faunal region, the latter belonging to the subantarctic proper. Therefore, so far as the echinoderms are concerned, it is most misleading to use the term ‘Subantarctic Islands of New Zealand’ to cover Auckland, Campbell, Antipodes and Bounty Islands.
A total of ninety-nine archibenthal and abyssal echinoderm species are known from the New Zealand region. Fell (1958) regards the archibenthal fauna as a mingling of local and cosmopolitan elements, shelf forms occasionally descending the continental slopes either by accident or design (e.g. Astropecten primigenius, Pentagonaster pulchellus, Heterothyone alba, Amphyicyclus thomsoni), and abyssal forms occasionally reaching the shelf. The relatively steep marine profiles facilitate the mingling of deep-water and shallow-water echinoderms, and a number of individual species tend to have a wide bathymetric range. For example, Paracaudina chilensis is common in Cook Strait in depths ranging between forty fathoms and 600 fathoms. This species is probably abyssal, and is also known from off Patagonia, Japan, Australia, California and Florida, probably achieving its distribution by spreading across abyssal bottom water.
The 69 known archibenthal species comprise 45 endemic forms (66%); 16 (22%) Australian-Indo-Pacific forms: 7 (10%)
Araeosoma thetidis, Paramaretia multituberculata, Zoroaster macracantha, Cosmasterias dyscrita and Amphicyclus thomsoni are known from New Zealand and the deeper waters off Australia. More sampling is needed in some critical areas before it can be decided whether the archibenthal echinoderms fit any horizontal distribution pattern. The same is true for the abyssal echinoderms
In conclusion it may be stated that we are continually reminded of our incomplete knowledge of the New Zealand echinoderm fauna. There are many discoveries to be made, and with these discoveries the apparent distribution patterns which have emerged over recent years will no doubt be modified. Nevertheless, it seems unlikely that there will be any drastic change in our present conception of the fauna.
Acknowledgement: I would like to thank Professor Fell of this Department for his instructive criticism throughout the preparation of this paper, and Professor Richardson for his many useful suggestions.
Of certain categories of red seaweeds R. M. Laing wrote in 1939: ‘Our ignorance of distribution is such that in most cases we are quite unable to give the exact range of any particular species.’ Though this is still all too true an attempt was made in 1947 to delimit marine algal provinces and a map showing suggested boundaries was published (Moore, 1949). Only a brief text accompanied the map and little of the evidence on which it was based was presented for possible alternative interpretation. Since 1947 there has been much activity in all fields related to New Zealand marine biology, including spectacular advances in physical oceanography which should ultimately contribute towards the understanding of patterns of distribution. Nevertheless there remain many miles of coastline, for example from Cape Runaway to Cape Palliser, where
To supplement and confirm published records the following collections have been examined: Auckland Institute and Museum herbarium, including that of L. M. Cranwell; Dominion Museum, including Travers specimens from Chatham Islands and many contributed by
From these varied sources some 200 species of apparently restricted distribution were listed, with deliberate bias towards plants of the more exposed habitats with which I personally am more familiar. Some promising examples had to be ignored because of uncertainty about taxonomic status. Not only are many small plants still very inadequately known but many large red weeds cannot be surely placed as to family, let alone to genus or species. The extremely carefully prepared and quite widely distributed sets of V. W. Lindauer's specimens provide an indispensable standard of reference even though, as he predicted, examination of these specimens by overseas specialists is showing that certain of his determinations require revision. It is still likely that, in spite of the comprehensive lists published for the Dunedin District by Naylor (1954a) and for
Distribution records of some thirty species are indicated on maps (Figs. 1 and 2) prepared by Trans. Roy. Soc. N.Z. 77(5), 1949, p. 188.
Euptilota mooreana) and this may well be confirmed when the rich red growths of such places as Mitimiti, north of Hokianga, and Paturau River mouth. N.W. Nelson, are fully analysed.
The bull kelps of the genus Durvillea are not shown on a map but are worth mentioning. These very large plants are not easily overlooked but just because of their size they have often escaped critical examination. As late as 1954 D. caepestipes was recognised on Chatham Islands where it is abundant, though not otherwise known in the New Zealand region (Naylor, 1954b). D. willana was described
D. antarctica, which has spongy fronds and simple stipe. It is still an open question whether D. willana grows on any of the subantarctic islands, where it would be expected since it is widespread round the South Island and occurs in Stewart Island; it is not known from Cook Strait but flourishes on the east coast at least for some miles north of Castlepoint. D. antarctica is a ‘wide’, growing on the roughest coasts from Campbell Island to the Three Kings and perhaps on the Kermadecs: on the east coast north of Hawkes Bay the few places suitable for this vigorous species are rather inaccessible but it definitely grows at Mahia Peninsula, off Anaura Bay, at Cape Runaway, on the northern tip of Great Barrier Island and on the Poor Knights. Considering only the species chosen for listing, at least ten from Kermadec Province, including several belonging to semi-tropical genera, do not reach New Zealand proper; forty or more come only from what is shown as Auckland Province; some twenty northern ones drop out about or north of Cook Strait while nearly thirty southern species do not extend beyond the line marked as the northern boundary of the Central Province. At least a dozen species are not known north of the Forsterian Province and there one otherwise very common weed (Carpophyllum maschalocarpum) is apparently lacking. The Rossian Province has a longish list of endemic species (several of the larger plants needing critical re-examination) and at least seven very common mainland plants have not been recorded — Carpophyllum maschalocarpum, Ecklonia radiata, Euzoniella incisa, Glossophora kunthii. Hormosira banksii, Splachnidium rugosum and Zonaria angustata. Chatham Province has a mixture of northern and southern plants, and has at least two large and well-authenticated brown weeds not known in New Zealand itself; no records have been published for many genera that one would expect to be plentiful, though some of them are represented in herbaria, and a check-list is urgently needed. There is certainly much in the Chathams that is common also in the Cook Strait area as with molluscs (Dell. 1960) and echinoderms (Fell, 1960).
Of some twenty genera reputedly endemic to New Zealand none are recorded from the Kermadec Province. About one-third are widely distributed round the coast, some extending to the Chatham and/or the Rossian Province. Four are definitely southern — the brown Marginariella with two large and well-known species, and three reds, each with one delicate sublittoral species quite fully represented in collections (Laingia, Marionella, Dasyptilon). The monotypic red Rhizopogonia is scarcely known beyond the shores of Cook Strait where it is locally abundant. The other endemic genera are represented by small, obscure or rare plants, including Perisporochnus from Three Kings.
Concerning extra-New Zealand relationships it will only be noted that among the species that do not extend north of the latitude of East Cape (37° 40' S.) the following are often quoted as illustrating south circum-polar distribution: Adenocystis utricularis, Ballia scoparia, Chaetomorpha darwinii, Chaetangium fastigiatum, Desmarestia firma, Halopteris funicularis, Macrocystis pyrifera, Phycodrys quercifolia, Schizoseris davisii, Scytothamnus fasciculatus. Other circum-polar species such as Ballia callitricha and Durvillea antarctica are not so restricted in New Zealand.
It is not proposed to discuss possible reasons for the distributions outlined. The object is rather to present these records in the hope that they will be checked and amplified by future collectors for comparison with occurrences of animals of various groups that live amongst these algae. Correlation with some physical factors may follow later.
Erratum: In Tuatara. Vol. 8, No. 3, pp. 97, 98, Hyla caerulea should be so spelled, not Hyla coerulea.
The swift flying, brightly marked yellow and black wasp Vespula germanica is becoming common over most of the North Island, and there is a scattered occurrence in the Nelson Province. The wasps are notable for their singleness of purpose and persistence in their work, and especially this is the case when in the late summer and autumn they are attracted into houses in search of sweet foods.
An effective trap can be made for these searching wasps by placing a short funnel in the neck of a large bottle. A suitable brew of jam or rotten fruit put in the bottle will attract the wasps to the trap.
Although the wasps are hard to distract from the job in hand they are quite tenacious if aroused, and will devote themselves completely to removing the cause of their annoyance. Movement around the entrance to a nest burrow quickly brings a circling defence of watchful wasps, whose numbers grow as the danger approaches. It may often be the case, however, that the defenders will not actually land on a person until the nest burrow is interfered with. The sting, which is quite painful, can be inflicted repeatedly by workers and queens, but not by drones, and the effect of the sting varies with the person, as it does with a honey-bee sting. Occasionally worker wasps have been seen caught in spider webs, from which they have nearly always been strong enough to escape. Several times wasps have been seen held in a web on to which the resident spider was hurrying to inspect the catch. Each time however, the spider, after approaching a short distance, turned and scuttled away, apparently not eager to tackle such formidable prey.
Once a blowfly with one wing, and a worker were seen tangled in conflict for about two minutes on a pavement. The fly managed to break away, and the wasp, left several inches distant, busily cleaned its head and antennae. After a few seconds the wasp turned and grasped the fly again. This time the pair spun around and around on the ground with the wasp on top. Eventually the fly escaped again and spun about three feet away. After a pause, the wasp moved quickly to a small brown piece of curled leaf about one foot away, and attacked that for a period. Upon finding that it had lost track of the fly, all the wasp's interest apparently vanished, and it flew to a nearby Clematis vine. Presumably the fly eventually died.
The spread of Vespula germanica in the North Island has been both rapid and unhindered to the present time, while the distribution in the South Island will undoubtedly widen. The origin of the spread is Hamilton in the Waikato, where in 1945 a number of nests were discovered. It is thought that some queens in hibernation arrived from Europe late in 1944 with aeroplane parts. Prior to this time, in 1922. some German wasps were identified in the Wairarapa, but apparently did not become established. Since 1945 the wasps have increased their range by natural means, but large distances have been covered mainly by rail and road transport carrying hibernating queens. Now, in 1961, Vespula germanica is numerous, and in having some affect on apiaries and orchards will grow in importance as its distribution widens. In an address to the 1960 Ecological Society conference, Dr. R. A. Cumber reported that in the north of the North Island Vespula germanica has depleted numbers of another previously common introduced wasp, Polistes humilis, possibly by competition for Lepidoptera larvae and flies on which both species feed. With regard to possible control of the German wasp, Thomas (1960) mentions an ichneumon wasp Sphecophaga burra as the most likely parasite.
Vespula germanica is easily identified at rest or in flight, since the body markings of bright yellow and black are so striking. The yellow colour of the body markings can be contrasted with the old-gold colour found in honey-bees. The queen, worker and drone are shown in Figures 1, 2 and 3 respectively, drawn to scale so that the body sizes can be compared. To help identify any wasps caught, especially specimens such as queen-sized drones, the following features can be used:
The antennae of drones have 13 long segments so that they are about one and a half times the length of the antennae of workers and queens, which are composed of 12 short segments. The abdomen of the queen is about the same length as that of a drone, but much broader, while the thorax and head are considerably larger. The worker abdomen is shorter than the drone abdomen, but the thorax and head are about the same size.
Apart from any wasps that may be discovered in a nest, wasps are most likely to be seen in the following ways:
Hibernating queens can be found in winter in many sheltered positions, such as under wood in a stack, or old sacks, in disused buildings or beneath loose bark. These queens are easily collected.
In spring the new queens emerge from their hibernacula and are often seen cruising backwards and forwards along banks searching for nest sites. They will frequently settle near, or hover over, cracks and burrows in the ground for a short time before moving on.
Workers will be seen on occasions, mainly in summer and autumn, engaged in collecting food (mainly insects) or wood fibre from lamp-posts, or coming and going from a nest burrow entrance.
Also in mid-summer and autumn drones and workers will come into the house in search of jams, fruit, meat and cakes, in fact a wide range of scented foods and liquids, and will be found in fruit either fallen or on the tree. The wasps will enter the fruit through a skin blemish, often caused by another insect, and will hollow it out completely leaving only the skin. In the middle of Wellington city in May, drones have been attracted by meat pies. In February in the Kaweka Range. Hawkes Bay, a worker was seen to drop on to a leg of meat, snatch a blowfly, and fly swiftly away. Blowflies are near in size to a worker, but the wasps will tackle insects much bigger than themselves.
In middle and late autumn drones can sometimes be seen weaving around the tops of bushes and trees prior to mating. In Wellington in May, drones have been seen flying in this apparently aimless manner round a Cupressus macrocarpa hedge for several hours on end.
Early in spring a mated queen comes out of hibernation and searches for a nest site, in a bank, hollow tree, or some other sheltered place. Sites which are exposed or which later prove unsuitable are often abandoned. The nest built by the queen comprises only several worker cells, and is a few centimetres in diameter.
The queen begins laying almost immediately, and larvae hatch after about three days. The cells are enlarged by the queen to keep pace with the growing larvae. The larvae moult three times and then pupate, the cocoon closing the end of the cell. The time taken for full development of a worker from a larva is not known accurately, but is between four and six weeks.
The fully formed workers chew open that part of their cocoon which closes the lower end of their cells, and emerge, ready to work after a period. Newly hatched wasps are not as bright in colour as older wasps, and have a superficial grey appearance owing to the retention of a thin covering formed round the pupa in the cocoon. Later this covering comes away revealing the distinctive yellow and black body markings of the adult insect. When the first workers have emerged, the queen devotes herself to egg-laying, while the workers enlarge the nest by adding new combs to the original comb built by the queen.
As spring passes into summer, workers are continually produced, until in late summer and early autumn drones appear in considerable numbers, eventually outnumbering the workers. At this stage the
Thomas (1960) offers the explanation that drones come from eggs laid only by workers, even when there is a queen present. Also in some nests large drones are produced in queen cells in late autumn. These drones have not been seen to mate, and Thomas suggests that they are raised from unfertilised eggs laid by the queen after exhaustion of sperm in the spermathecae.
When new queens have matured in late autumn, mating commences. The drones leave the nest and congregate round nearby bushes and trees until the queens emerge, following which mating occurs.
After mating, and a brief return to the nest, the queens seek a place in which to hibernate for the winter, while the drones remain in the nest. As winter approaches workers and drones search widely for food, eventually turning on each other as well as remaining larvae and pupae until the nest is left empty.
In places where frosts are uncommon a nest with its functional queen may remain active instead of being deserted by the colony. Sections of the nest may be closed off by papery partitions, while the combs in use may carry worker, drone, or queen broods, the last being the most common. The following spring the colony picks up again to repeat the previous year's activities, and may possibly remain active for a further season if conditions are suitable. Hibernating queens emerge in spring and search for nest sites to commence new colonies.
Briefly summarised the life history is as follows:
A mated queen emerges from hibernation in spring. The queen finds a nest site and establishes a small nest. The first workers produced take over nest maintenance while the queen settles down to lay eggs. In late summer and autumn drones and new queens are produced. Drones and new queens mate, following which the queens hibernate. Activity in the old nest decreases as winter approaches, and eventually ceases. Occasionally nests may remain active over winter if conditions are suitable, and may be active through a second summer.
The nest is commonly situated in an earthy bank (see Fig. 4) and is usually a foot or two below the surface, though a nest may grow to be close to the surface, In one nest investigated the nest wall was only a quarter of an inch from the surface of the bank which was not very stable, and workers were seen dabbing bits of soil with their jaws on to the outer side of the thin portion of the bank. The ‘dabbed’ portion covered some four square inches, and was quite noticeable. Presumably the original burrow was short, and the nest quickly grew out towards the surface.
Nests may be above ground, however, in suitable sites in trees or buildings but this is less often the case. A nest may range in size from a few cells occupying one or two cubic inches, to a structure several feet in diameter.
As shown in the figure, the nest partly hangs from grass rootlets immeshed in the wall, and partly rests on the stone and pebble foundation. Nests near the ground surface may have so many rootlets caught into the walls that removal of the nest intact is extremely difficult. Usually one entrance leads to the nest and the burrow may curve vertically or horizontally before the chamber is reached. The burrow may not open directly opposite the entrance to the nest itself.
The shape of the nest is usually ovoidal or sub-spherical but the shape is eventually governed by the nature of obstructions in the bank. Workers carry out tiny pebbles and fine soil particles in their jaws and drop them away from the entrance. There is a space which varies in width, around the nest, but it is usually about a quarter of an inch wide. Rocks in the bank may project into the nest wall, while pebbles that are too big to carry out are sometimes simply incorporated in the nest wall. Beneath the nest small stones form a foundation which is probably unintentional, the stones being cleared of their surrounding soil in the course of growth of the nest. The clear space enables workers to move round the nest, removing earth to allow for further enlargement, and together with the foundation probably helps to move draining water past the nest.
The nest wall is composed of greyish scale-like papery material. It is closely but loosely layered and the scales continue haphazardly from one layer to the next. Together the layers form a wall varying from a quarter of an inch to one inch thick in small nests, while one large nest has been recorded from the Raglan district (Thomas) with walls one foot thick in places. This nest was situated in a tree. The papery material is brittle and is formed from chewed wood fragments. Workers will often be seen busily moving over lamp-posts and scaly barked trees collecting tiny pieces of wood with mandibles and forelegs. Once a lamp-post is established as a good source it is visited again and again. Although the scales are brittle, collectively they are resilient but are only slightly waterproof. The scales are
Many layers or combs comprise the nest within its wall. These combs are held apart and supported by little struts which leave space enough for the wasps to move about the cells. The struts are made from rechewed nest wall paper, as are the cell walls. Growth of a nest is commonly downwards, new layers being added below the existing ones. The number of combs present in a nest will depend on how old the nest is, and the time of year will determine whether predominantly workers, drones or queens are being produced. Drone cells may be found from late February till May or June, while queens appear in April and May. There are two types of cell, the smaller ones giving workers and drones the larger giving queens and sometimes drones. These large drones are not numerous, and may not mate. An individual cell may be used several times in a season.
The cells of each comb open downwards, i.e. the bottom of each cell is on the upper side of a comb. The cells are built down as the larvae elongate, and the mouths of the cells are closed by tough silken cocoons spun by the larvae themselves. These silken cell floors are almost white in colour and are readily distinguishable from the grey walls of the cells.
Methods of destroying nests are varied, but if the nest is required for examination, quick-acting poisons are needed so that it is not damaged. One method involves the use of chloropicrin, and is simple to carry out. but care is needed since the poison is dangerous to man. This poison is available on signature from the New Zealand Fruit Growers' Federation. It is contained in small glass phials, the tops being snipped off before insertion, neck downwards, in the entrance of the burrow. The liquid poison gives off fumes which penetrate very well indeed, accounting for all the wasps except the inevitable stragglers which, nevertheless, soon die. A sod of earth, or a sack can be placed over the hole afterwards. The operation should be done after dark with the minimum of noise and disturbance, since in summer (when most nests are located), there will often be wasps resting in the tunnel leading to the nest. After treatment the nest can be left overnight and later carefully dug out.
Preservation of a nest for examination is easy. Simply put it in a box with a loose fitting lid, and keep it in a dry place. The wasps and their larvae will dry out and shrink but otherwise the nest will
Acknowledgement: The writer wishes to thank Miss
The genus Coprosma has its greatest concentration of species in New Zealand, where there are about forty of the ninety known species. The remainder are scattered through the Pacific, and fall within a line including Tasmania. Eastern Australia, Borneo, Hawaii, Juan Fernandez Islands and New Zealand's subantarctic islands. The genus was first collected by Banks and Solander in New Zealand on Cook's first voyage, but as their descriptions of seven species were never published the name valid to science originates from the Forsters, father and son, who came as botanists on Cook's second voyage. They found two species, one of which forced itself to their notice by its unpleasant smell, strongly reminiscent of carbon disulphide. As a result of this disagreeable first impression they stigmatised the whole genus with the name Coprosma meaning ‘smell of dung’, and applied the specific name foetidissima, ‘extremely vile smelling’, to the offending plant. Possibly this was uncharitable considering that only two species of the genus have a noticeably obnoxious smell, the New Zealand endemics C. foetidissima and C. crenulata. On the other hand, a friend of mine who used to live on Stewart Island remembers that she was taught to avoid mikimikis (Coprosma spp.) completely when collecting firewood, because even the seemingly inoffensive kinds were transformed into ‘stinkwoods’ by heat. The odour of
C. foetidissima has been shown by Sutherland to be caused by traces of methyl mercaptan, and it would be interesting to know whether similar compounds occur in other Coprosma species, or in the related genus Nertera of which N. depressa at least smells like C. foetidissima.
Coprosma belongs to the family Rubiaceae, which includes such useful plants as Coffea and Cinchona, yielding coffee and quinine respectively; and Rubia, the madder, a source of red dye. Other New Zealand genera are Nertera and Galium. Nertera is close to Coprosma from which it is distinguished by its herbaceous habit and bisexual flowers. It grows in mats which would be hardly noticeable except that in season they bear a mass of shining orange-red fruits. A form with the popular name of ‘bead plant’ is sometimes cultivated in rockeries. Galium is a square-stemmed herb with small dry fruits consisting of two nut-like halves. An introduced Galium is well known for its ability to stick to clothes and skin by means of a covering of minute hooked hairs.
Coprosmas are all woody, but range in habit from creeping mat plants through different forms of shrub to small trees, and occur in all kinds of vegetation from the sea coast to the mountains. They have opposite pairs of leaves, interpetiolar stipules and pits or domatia can be found in all but the very small-leaved species. The stipules of Coprosma are not exactly equivalent to the paired lateral structures of the same name found at the base of the petiole in some alternate-leaved plants. In peas and beans, for instance, these are leaf-like, and could be thought of as similar in form and origin to the normal leaflets borne further out along the main axis of the leaf; but a Coprosma stipule bridges the gap between the bases of opposite leaves, and the two stipules and two leaf bases together encircle the node. In simple cases the stipules are more or less triangular, and may be either prominent or minute. They appear at every node on the plant including the cotyledonary node, in the form characteristic of the species. This interpetiolar type of stipule is probably best interpreted according to the theory of Sinnott and Bailey as a fusion of two formerly independent lateral stipules, since its venation is derived from the leaf traces on either side.
It is interesting to note that in Galium, the interpetiolar stipules are prominently expanded and leaf-like, with one or several occurring between the bases of each leaf pair, so that together the leaves and stipules form a whorl of similar organs at the node. So alike are the members of the whorl that the only reliable distinction between them is the presence of buds in the axils of the true leaves.
The stipules in Coprosma are associated with a complex collar surrounding the stem above the node and enclosing the two axillary buds. Fig. 1 illustrates the stipule collar of C. robusta cut away to show the nature of its parts. The two triangular stipules are joined to each other by a band of thinner tissue across the leaf axils and above the leaf abscission zones. This thinner tissue is the stipule
Figure 2: Coprosma robusta Raoul
C. robusta has both sheath and cup contributing to the stipule collar but in other species either one or the other may be developed. A deep stipule cup is often indicated by a band of green tissue persisting at the node when bark has been developed above and below. Any kind of stipule collar will at first constrict the axillary buds but later their growth hastens its rupture and loss.
Stipules probably always bear denticles at their upper free margin. These are stumpy or pointed outgrowths (literally ‘little teeth') which appear on close observation to be covered with a shining translucent jelly. Microscopic sections reveal the jelly to consist of elongated glandular cells packed into a dense palisade over a core of soft tissue. When the tips of the glandular cells break, their mucilaginous contents are released as a shining coating easily seen if young growing leaves are prised apart. In time this mucilage dries into a horny film and disappears. After the release of their contents the glandular cells shrivel while the internal tissue darkens and withers, reaching this stage at about the time the leaves of the same node are mature. Thus denticles, like the stipules which bear them, reach their fullest development at an early stage and their secretion probably protects the tender growing leaf tissues from desiccation. In C. serrulata and C. foetidissima the denticles are slim and could be regarded as multicellular hairs with a specialised glandular function. C. lucida and C. repens have similar but fatter, shorter denticles lacking the basal non-glandular portion of the slim ones. However, in C. robusta, C. tenuifolia, C. arborea and C. macrocarpa, the glandular region is the stipule apex itself, and although this is also usually referred to as a denticle, it is not quite the same structure as the hairlike denticles described above. C. australis stipules exhibit a particularly interesting intermediate condition, where the stipule apex is glandular as in C. robusta, but the glandular surface extends downwards and laterally to cover two rows of marginal projections which seem to correspond with the hairlike denticles of other species. The first pair of stipules on an axillary shoot is very compressed during development, and frequently the stipule nearest to the axis has a twinned apex. This is particularly noticeable in species with a simple glandular apex. e.g. C. robusta, C. macrocarpa and C. tenuifolia which have therefore been reported as having 1-2 stipular denticles. Twinned apices also occur in a similar position on axillary shoots of C. lucida and C. repens.
A Coprosma twig has a series of stipules from tip to base which vary in appearance from young to senescent. In some species the
Figure 4: Coprosma lucida J. R. et G. Forst.
The leaf pits or domatia in Coprosma are shared by its relative Coffea. They occur on the underside of the leaf in the acute angle made by the midrib at its junction with major secondary veins. Their sizes and shapes include variations from wide-mouthed shallow depressions to enlarged cavities entered by a tiny pinhole. They usually produce a raised blister on the upper surface of the blade. Domatia associated with secondary veins have been reported by Shirley and Lambert as occurring very occasionally in C. repens, and have also been observed by the writer on larger shade leaves not only in C. repens but also in C. australis and C. foetidissima.
The function of domatia is still a matter for speculation. Those who hold that they are shelters for small insects would call them domatia, meaning ‘dwellings’, and point out that other genera of Rubiaceae provide domatia for ants, Myrmecodia in a corky basal tuber, and Duroia in hollow stems or leaf swellings. Certainly small insects are often found in the pits, but they could have come upon this convenient shelter by accident. Others suggest that the occurrence of bacterial nodules in the leaves of Psychotria may give a clue to the nature of Coprosma pits. The bacteria of the nodules are beneficial because they fix atmospheric nitrogen, and are carried by the host from one generation to another by means of the seed, whence they invade the apical bud of the new plant and live in a gummy secretion inside the stipular sheath, infecting each new leaf as it develops. This recalls the secretions from Coprosma denticles and led Stevenson to investigate their bacterial content. She reported that the glandular cells as well as the secretion are full of bacteria and taking this together with other evidence that C. robusta at least is able to assimilate nitrogen from the air, concluded that the bacteria might be the agents responsible. However, the demonstration is not yet absolutely conclusive, and the relationship of the bacteria with the pits is not clear. The whole question is probably best left open for further investigation.
The leaf of C. serrulata has a remarkable colourless border which contains near its inner edge a small vein running parallel to the margin, and whose free edge projects in regular crenulations. Apart from a few references to thickened margins in other species, Coprosma leaves in general seem to be regarded as having unspecialised margins. Detailed investigations of leaf margins show that there exists a variety of conditions, from borders very like those of C. serrulata to an absence of any specialised structure. Oliver mentioned that the leaf margin of C. crenulata approaches