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Tuatara aims to stimulate and widen interest in the natural sciences in New Zealand, by publishing articles which (a), review recent advances of broad interest; or (b), give clear, illustrated, and readily understood keys to the identification of New Zealand plants and animals; or (c), relate New Zealand biological problems to a broader Pacific or Southern Hemisphere context. Authors are asked to explain any special terminology required by their topic. Address for contributions: Editor of Tuatara, c/o. Victoria University of Wellington, Box 196, Wellington, New Zealand. Enquiries about subscriptions or advertising should be sent to: Business Manager of Tuatara, c/o. Victoria University of Wellington, Box 196, Wellington, New Zealand.
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is the journal of the Biological Society, Victoria University of Wellington, New Zealand, and is published three times a year. Joint Editors:
Virginia or White-Tailed Deer were introduced to New Zealand shortly after the turn of the century. Considered excellent hunting in their native habitat of North America, they were introduced for the purposes of sport. Two liberations were successful, one on Stewart Island, the other on the western shores of Lake Wakatipu. and the deer have remained confined to these areas. Concern over the damage inflicted by these and by red deer (Cervus elaphus) led to the removal of protection in 1925.
Virginia deer are placed in the Order Artiodactyla, Family Cervidae. Simpson (1945) includes them in a sub family Odocoileinae Pocock, 1923, but this is not mentioned in Hall and Kelson (1959), who place Virginia deer, together with black-tailed deer, in the genus Dama Zimmerman, 1780. However, the International Commission on Zoological Nomenclature (China and Melville, 1959) invalidated Dama Zimmerman, declaring Odocoileus Rafinesque, 1832 the correct genus for Virginia deer.
Odocoileus virginianus was first described by Boddaert (1785). The specific name virginianus is derived from the State of Virginia (the type locality) where this deer was found early in American history. Thirty subspecies are recognised throughout the range of the species, which extends from Coiba Island, Panama (O. virginianus rothschildi) to eastern Canada (O. v. borealis) and British Columbia (O. v. ochrourus).
The Virginia deer is also called the white-tailed deer owing to the conspicuous white tail which it holds upright when fleeing from danger. In North America the name white-tailed deer appears to be the most popular common name whereas in New Zealand it is Virginia deer. Other common names used in the United States are red-deer, common deer and karjacow (Donne, 1924).
Like many deer species, Virginia deer appear, at first glance, larger than they actually are, especially when only a glimpse is caught through the trees. On closer examination they prove to be slight and somewhat smaller than red deer. Height at the shoulder is about 3ft.: females are usually smaller than males. Blair et al (1957) point out that size varies considerably. Weight ranges from 50 to 350lb, but the average for males is between 120 and 150lb while females usually weigh between 80 and 100lb.
The upper parts of the coat are brownish red to grey in summer (a brighter red than the summer coat of the red deer), and become greyer in winter. The under parts of the body are white, as are the lower surface of the tail, the chin and throat, an area around the muzzle, and a ring round the eyes. The young are spotted, white on a reddish background, the spots being lost between the ages of three and four months. In New Zealand the change from summer to winter colour usually takes place in March and April and the winter-to-summer change in August and September, but these dates may vary considerably. The tail is very conspicuous because of its length (12-18in.) and its white underside (Fig. 1).
In common with other members of the Cervidae, only male Virginia deer (bucks) carry antlers. The main beam curves forwards with times arising vertically from it, brow tines are absent, and other tines are generally unbranched. Good antlers reach a length of 23-29in. (Riney, 1955) and occasionally may have up to 16 points.
Virginia deer have well developed senses of sight and smell. Their eyesight is particularly well attuned to movement, in this respect being more acute than that of red deer, but they seldom discern stationary objects. Their hearing is acute and they become alert at any strange or sudden sound; they seem especially aware of metallic sounds. In contrast with red deer, Virginia bucks are not vocal during the rutting period. Like most other species of deer they emit few noises and even then usually only if alarmed, when they blow through their nostrils. Sometimes a fawn will give a quiet bleat. When in flight their running is interspersed with a series of graceful leaps.
Virginia deer range from northern South America through Mexico and the United States to southern Canada. There is evidence that previously they inhabited all of the United States except some of the more arid areas, but have disappeared from many parts of their former range (Blair et al., 1957).
There is a wild introduced herd in Finland and there are some feral Virginia deer in England. Apart from these and the New Zealand herds the authors do not know of any Virginia deer established outside their present native distribution.
Four Virginia deer (two males and two females) were liberated in the Takaka Valley, Nelson, in 1901. It is not known who was responsible for this liberation or where the animals were obtained. This liberation was not successful.
In 1905, Five mule deer (Odocoileus hermionus), a deer very similar in appearance to Virginia deer, were also acquired by Donne at this time. These animals reached New Zealand in good condition and were liberated at Runanga, Hawkes Bay (Donne, 1924). In 1915 these deer were reported by the Hawkes Bay Acclimatisation Society to be increasing in numbers, but since then nothing has been heard of them and the liberation appears to have failed.
The herd on Stewart Island became well established and in 1917 the Southland Acclimatisation Society reported that the herd had increased considerably. Press reports in 1919 stated that it was a ‘splendid herd’ and two licences to shoot Virginia deer were granted. At the present time the highest densities of Virginia deer on Stewart Island are found in the northern part of the island, close to the coastline.
The herd at Lake Wakatipu has remained largely confined to the Rees Valley. It is only recently that they have become established in the adjacent Dart Valley (Fig. 2).
Virginia deer inhabit forest, forest edges and bush along stream edges. They avoid very dense bush, especially if it is damp, and
As with other members of the Cervidae, the sexes remain separate during most of the year except during the rut. In New Zealand this usually starts at the beginning of May and reaches a peak by the middle of that month, i.e. about 25 days later than that normal for red deer. Just before the start of the rut the bucks travel freely. Unlike red deer stags. Virginia bucks neither ‘roar’ nor wallow during the rut. Females usually breed in their first year if they are in good condition.
Young are born in December and January after a gestation period of approximately seven months (204 days according to Asdell, 1946). In their native habitat Virginia deer usually give birth to twins; triplets are not uncommon and quintuplets have been recorded. However, twins are rarely recorded in New Zealand. (One twin foetus was recorded in the Dart Valley in 1963, and twins are occasionally seen on Stewart Island.) The frequency of multiple births appears to be a reflection of the suitability of the environment, and it has been considered that the present environment of the Virginia deer in New Zealand is not entirely suitable. This view is supported by their failure to extend their range and by the generally poor condition of Virginia deer in New Zealand. In the Dart and Rees Valleys Virginia deer fawns are dropped a little later than those of red deer, but on Stewart Island the time of birth may be spread over most of the year; the mild climate of Stewart Island when compared with that of the Dart and Rees Valleys has been given as a reason for this (Daniel, pers. comm.). Fawns require milk up to the age of three months, and stay with the mother for eight or nine months. The association is usually broken when the doe is ready to have her next fawn. The conspicuous tail of the Virginia deer is used by the doe as a guide for the fawn as they run through the forest. Bucks also raise the tail, exposing the white under side, when they run from danger.
Virginia deer are quick to learn and to profit from experience. They will circle when they run from dogs; often they will let a person, or dog, approach and pass before quietly moving away. They make and frequently use ‘runways’. Once used to man, they will tolerate his presence, and in their native habitat Virginia deer may be found in large numbers on the edges of some of the big cities (Hall and Kelson, 1959). At Paradise Station (Glenorchy, Lake Wakatipu, South Island. New Zealand) Virginia deer can be observed by tourists, grazing at the bush edges.
Virginia deer will readily take to water, especially if pressed by dogs, and have been seen to swim for more than an hour and a half in calm water (Schofield, unpublished ‘report’). Bucks have swum more than three miles during the rutting period.
The parasitology and diseases of Virginia deer have been the subject of extensive investigation in their native country (Deer Disease Symposium. 1962). The New Zealand herd is currently being studied along similar lines by one of the present authors (J.R.H.A.). Preliminary findings from the Lake Wakatipu herd show the presence of dog tapeworm (Taenia hydatigena) cysts on the liver and omentum, a nematode (Oesophagostomum venulosum) in the caecum, and six species of trichostrongylid nematodes in the fourth stomach. The deer that were examined were in remarkably poor condition. Samples of blood taken from these animals failed to show the presence of Brucella or Leptospira organisms (Daniel, pers. comm.). The louse (Damalinia parallela) commonly found on North American Virginia deer was also present.
In North America Virginia deer are host to a wide variety of parasites, including a number that are shared with other wild and domestic ungulates (Anderson, 1962).
Virginia deer were protected until 1919, when regulations were gazetted for shooting under licence. In 1925, as a result of representations made to the Government, all protection was removed. The number of Virginia deer shot either by Government hunters or by private shooters is not known. Extensive operations against both red and Virginia deer on Stewart Island reduced the numbers of the red deer, but Virginia deer, because of their more wary nature and their habit of occupying bush country, remained numerous.
Virginia deer have little commercial value. It is hoped that they may provide a tourist attraction in the Wakatipu (Glenorchy) area. Donne (1924) observes that Virginia venison is highly recommended because it is readily digested. The meat is lighter in colour than that of red deer, not as coarse, and can be very tender. Donne also quotes Theodore Roosevelt as stating that ‘Whitetail venison is most delicious eating’.
E. L. Hellaby Research Fellow.
An Earlier Account by Wardle (1963) presented an hypothesis of Pleistocene extinction of plants in the central South Island, and the likelihood of the presence of Pleistocene refugia in the extremities of the Island, among other places. The present writer, independently, had come to similar conclusions from study of distributions of species in the South Island. This paper was written in the belief that it could add considerable detail to the chain of evidence presented by Wardle and elucidate some of the problems of distribution.
Two groups of plants are disjunct For plant geographical terminology see Cain (1944). Readers are referred to A Descriptive Atlas of New Zealand for place names.
The second striking series of disjunct species consists of plants with a conspicuous gap in their known distribution in the central South Island. Wardle listed a few of these and drew on the presence of a relatively large number of endemic plants in each of Otago-Southland and Nelson-Marlborough, with correspondingly few endemics in the central South Island, as support for his hypothesis of Pleistocene extinction in the latter area. An implication of the hypothesis is that Nelson, Marlborough, Banks Peninsula, coastal Southland. Stewart Island and offshore islands were refugia where large numbers of species including some forest plants survived the glacial maxima of the Pleistocene.
In examining, the present distribution patterns of species disjunct between the northern and southern parts of the South Island, and of endemics in both these areas, the present writer came to the conclusion that a simple statement of Pleistocene extinction in the central South Island did not explain all the facts of distribution. The detailed knowledge of distribution of plants and vegetation, together with information from non-botanical fields, allows elaboration of the hypothesis as formulated by Wardle. In this article evidence is brought forward in support of a modified hypothesis.
It is proposed here to deal with species fully disjunct between Nelson-Marlborough (and/or North Island) and Otago-Southland (and/or Stewart Island); with closely related (vicarious) species, whose distributions do not meet in the central South Island; with species which are abundant to north and south of the South Island and less common between; with the patterns of distribution of species endemic to the north and south of the South Island; with some distributions which indicate that the populations of these plants have undergone recent contraction: and with some disjunct animal distributions.
The species fully disjunct between the northern South Island (and/or North Island) and southern South Island (and/or Stewart Island) in a few cases extend to the Auckland or Campbell Islands. The gap in distribution varies in width and is obvious from distribution maps (Figs. 1, 2, 3 and 4). The extremes in separation are those for populations of Juncus procerus (Edgar, 1964), 1650 miles, from Auckland to Southland) and for Drosera pygmaea, from the Volcanic Plateau to Bluff Hill (more than 600 miles). In the South Island proper there are patterns held in common by numbers of species. Many of the species are confined to the Gouland Downs-Tasman Mountains-Mt Arthur-Paparoa Range areas in the north and to Stewart Island-Fiordland-Longwood Range-Blue Mountains-Maungatua in the south. The ranges of other species are further to the south in Nelson-Marlborough and to the north in Otago-Southland with limits in various places, a few extending as far as Canterbury-Westland. One species (Pimelea aridula)‡ is centred on Central Otago and central Marlborough, and lives on dry, rocky hillsides. It extends also to Hawkes Bay. The other full disjuncts include Mitrasacme novae-zelandiae*, Petriella thomsoni*, Hemiphues suffocata*, Pseudalepyrum pallidum*, Tetrachondra hamiltonii*, Gentiana saxosa†. Drosera pygmaea*, Drapetes laxus†, Senecio reinoldii‡, Celmisia petriei‡, C. traversii†, Ourisia macrocarpa var. macrocarpa† (found only once in northwest Nelson). O. modesta* (a rare plant). Parahebe catarractae‡, Myosotis tenericaulis‡,
Pimelea gnidea‡, Elytranthe colensoi**, Melicytus macrophyllus‡ (found in one locality near Dunedin), Juncus procerus‡, Nothofagus fusca‡, N. solandri var. cliffortioides‡ (hereafter called N. s. cliffortioides), Lyperanthus antarcticus*, Rubus australis‡, Hebe salicornioides‡, Atriplex novae-zelandiae‡, Lepidium tenuicaule‡. Those species marked * are confined to boggy habitats. The implication that bogs are also limited to the same areas is generally true for the cushion bog type which is the habitat for most of these plants. Extensive cushion bogs in the South Island are found only north of about the Taramakau-Waimakariri Rivers and south of about the Haast Pass. Extensive raised sphagnum bogs are also limited in much the same way although a few occur in central Westland where conditions for their formation are very favourable. An hypothesis to account for the bog disjunction will also account for disjunction of the individual plants. The other strictly habitat limited plant (marked **) is an Elytranthe, usually parasitic on Nothofagus menziesii which itself has wide gaps in distribution but is found in a few places in the central South Island. The other species (marked ‡ and †) are not apparently habitat limited at present and there seems to be no disability which prevents their potential migration into the central South Island. Species marked ° are normally alpine and those
There is a group of several pairs of morphologically similar species in which one of the pair is distributed in Otago-Southland and the other in Nelson-Marlborough or North Island. There is, thus, a gap in the central South Island in which the pairs of species do not meet. These pairs seem to be closely related or vicarious species. It may be speculated that they have experienced evolutionary divergence comparatively recently (probably following separation earlier than the disjunct species were separated). They are enumerated below.
The distribution patterns of a further group of species show that they are generally abundant in the north or south of the
Nothofagus menziesii occurs in the north west and south west and south of the South Island but is found in at least three scattered localities — near Burkes Pass, at Lake Heron and in the Karangarua Gorge, between the main areas of occurrence. The Armstrong herbarium of the Canterbury Museum contains two specimens of each of Nothofagus menziesii and N. fusca labelled as having been collected in the Upper Rangitata and Upper Ashburton Rivers in 1869 but these distributions require verification. Adenochilus gracilis nearly always accompanies Nothofagus fusca. There is one known occurrence of this orchid in the Whitcombe River, a tributary of the Hokitika River. Festuca matthewsii is an important component of alpine and subalpine grasslands in Marlborough (Wraight, 1963) and about and south of the Waitaki River (Connor, 1961), but although occasionally present is very inconspicuous in grasslands between. Geum leiospermum, Liparophyllum gunnii, Schizaea fistulosa var. australis and Oreostylidium subulatum have similar patterns of distribution, the
There are sufficient endemic vascular plant species in the South Island confined within the areas north of a line from about Greymouth to Motunau and the south of a line from about Bruce Bay to the Waitaki River mouth to enable the northern and southern floras to be regarded as distinct from the rest of the South Island flora (see Wardle, 1963a; approximately 110 endemic species in Nelson-Marlborough and 90 in Otago-Southland excluding the Foveaux Strait species). The central South Island proper, however, is characterised by relative poverty in endemic species, with only about 14 such species being confined approximately within the boundaries described above, four of them on Banks Peninsula. Some of these central South Island endemics are plants of rupestral habitats and others favour periglacial habitats up to about 9000 feet in the high Central Alps (Myosotis explanata, Ranunculus godleyanus, R. grahamii). Rupestral, scree and high altitude species of somewhat wider distribution will be discussed later. Individual distribution patterns of the endemics which have been grouped here into Nelson-Marlborough and Otago-Southland floras resolve the endemics into minor groups centred on focal areas within both northern and southern South Island. Thus there is a group centred on northwest Nelson and a smaller group in eastern Nelson, and Marlborough including the Kaikoura ranges. Similarly in the south a group centres on Fiordland and another on Central Otago. These may be designated ‘western’ and ‘eastern’ facies respectively, but individual species transgress any boundaries which may be drawn. The fully disjunct species and vicarious pairs of species have similar distributions. It is not intended to enumerate the distributions of these endemic species in detail. The generalised patterns of distribution will be described with the aid of a map (Fig. 7). From Fig. 7 it is seen that northern patterns may be grouped into at least nine ‘types’. These are designated only for convenience in description. Individual distribution patterns show great complexity, with each species tending to behave independently. Each ‘type’ is named here according to the absolute southern limit of the species within it and is characterised by the presence of at least three species.
Since this article was written further field work reveals that another group of southern species has its northern limit in the Haast Pass-Lake Ohau region. The species include Dracophyllum menziesii, Coprosma astonii, Ranunculus buchananii.
In all the patterns so far described the species involved are relatively abundant and continuously distributed within their area. Later in this account there are also recorded a few cases of species from northern and southern New Zealand which show considerable disjunction between continuous populations and other known localised occurrences. This is probably to be related to contraction of areas.
The general situation as expressed in Fig. 7 is that from several centres (which are probably centres of dispersal), species distributions radiate outwards. Common limits are reached by groups of species, but patterns tend to be different for each individual species. This is to be expected in view of the likely differences in tolerance ranges between different species. The patterns tend to be eccentric about the centres of dispersal. There are tendencies for species to be restricted towards west or east and this is reflected in the presence of ‘western’ and ‘eastern’ facies. but some of the species extend into both western and eastern areas. It seems clear that species have migrated outward
A further situation complicates the position with respect to the hypothesis of Pleistocene extinction in the central South Island. Outside the main areas of distribution of numbers of species there are found distant, isolated occurrences. The ‘partial’ disjuncts described previously are of this type, but many others also exist which are not dicentric. Again, in these monocentric patterns the tendency is for a distribution to tail-off into the central South Island. The gaps between populations seem too great to have been bridged by long distance dispersal. In most cases, too, the apparent lines of dispersal lie athwart prevailing wind gradients or likely pathways such as river valleys and mountain ranges. Contractions of area are believed to be the explanation for these distributions. Species which appear to have contracted northward are: Celmisia allanii, continuous to the Hurunui River, one occurrence in the Godley River: Hebe cheesemanii, continuous to Hurunui River, occurrences at Mt Peel, South Canterbury, Kirkliston Range and Mt Alta, Otago; Ranunuculus insignis (‘monroi’ type), continuous to Waimakariri River; occurrences at Mt Hutt, Mt Peel and Four Peaks; Leucogenes leontopodium, local but not uncommon on North Island and Wairau Mountains, isolated populations at Hurunui River and Mt Peel; Hoheria sexstylosa, common to about 40 deg. 30 min. south latitude, occurrences on Banks Peninsula (possibly now extinct) and near Gore; Pittosporum patulum, local but not uncommon north-west Nelson to middle Clarence Valley, occurrences near Lake Ohau. Species which appear to have contracted toward the south are Euphrasia dyeri, not uncommon in bogs in Stewart Island, Fiordland, Southland and South Otago, occurrences at Mt Kyeburn and Mt Somers; Coprosma intertexta, common in Southland-Otago, occurrences at Cass, Waiau River, Rahu Saddle, north-west Nelson; Olearia moschata, common along the main divide to about Mt Cook, less common in Rangitata and Rakaia Rivers, rare at Arthurs Pass, represented by hybrids with O.
avicenniaefolia (= O. haastii) in the Waiau River and probably by hybrids with O. nummularifolia at Boulder Lake in north-west Nelson. It may be noted here that the dicentric Nothofagus fusca which also has outlying populations in the central South Island, is sometimes represented there by hybrids with N. s. cliffortioides where no pure individuals of the former species are now found. Wind-blown pollen could account for this in some cases.
It seems probable that these monocentric and some or all of the ‘partially disjunct’ dicentrically distributed species have undergone contraction later than the separation of the species regarded as full disjuncts. Some of the latter may also have had their areas contracted.
Some animal distribution patterns fit into the general patterns of plant distributions outlined above. Powell (1957) described the following marine animals with disjunctions in their distributions between North Island and South Island: the mollusc Amphidesma ventricosum (toheroa) and at least one other mollusc and a species of brachiopod. Fleming (1950) described a molluscan fauna from the coast of Fiordland containing three genera and 16 species otherwise known only from North Auckland or North Island. Mr P. Johns (pers. comm.) states that although there are no species known by him to be disjunct between Nelson-Marlborough and Otago-Southland, certain groups of species of the terrestrial animals, ground beetles, millipedes and cockroaches are closely related in the two areas, separated by a gap in the central South Island. They are probably equivalent to the pairs of vicarious plant species. Similarly, the distributions of individual species extending into Canterbury from north and south are parallel in many cases to plant distributions. Lee (1956, 1959) recorded that one genus of earthworms in New Zealand was represented only in Fiordland and Auckland Province, and three species of Taranaki-Wanganui are most closely related to species of the south-western South Island and subantarctic islands. Comparatively unspecialised faunas consisting of widespread species are present in the eastern South Island. Westland is likewise unspecialised with respect to earthworms but there are some endemic species and the area had been colonised from both north and south. Banks Peninsula is also an area with a small number of endemic earthworms. The Wellington-Nelson area is regarded as a centre of dispersal for these animals.
Distributions of many plants and some animal groups suggest that there is a real floristic-faunistic gap in the central South
A brief consideration will now be made of the role of glaciation and post-glacial climatic changes in bringing about discontinuous distributions. A more detailed account of these changes, together with interpretations of the available pollen analyses will be published elsewhere. References for the statements made below are included in Burrows (1964 M.S.).
The last major glaciation, known as the Otira Glaciation (Gage 1961), was preceded by an interglacial in which there is evidence for mild climates and vegetation similar to the present in the South Island. This probably is the time when most of the plant species now disjunct were distributed throughout the Island. The onset of the first stadial of the Otira Glaciation brought about their disjunction. The vicarious pairs of species may have evolved after disjunction brought about by one of the earlier Pleistocene glaciations. Even at the height of each stadial some vegetation would have survived throughout the South Island. This would have included scrub and tall and short tussock grassland composed of unspecialised species now widely distributed. Specialised species of scree, rock and ‘periglacial’ sites would also have been present in the many suitable habitats. Many other species including forest trees would have been limited by cold to refugia in extremities of the island. During the interstadials before the last (Blackwater 2 and Poulter) ice advances of the Otira Glaciation (Gage and Suggate 1958) forest species including B.P — before 1950 A.DNothofagus s. cliffortioides and N. menziesii expanded into the central South Island (as they probably did during each interstadial, to be pushed back as the next ice advance began). This vegetation was probably not completely dislodged from the centre of the Island by the subsequent ice advances. It was, however, likely to have been severely limited. Soon after the retreat of Poulter ice about 15,000 years B.P.Phyllocladus alpinus, Dacrydium biforme) and the larger
Podocarpus hallii, with scrub and grassland existed east of the main divide in the centre of the island proper. In central Westland the vegetation was much as it is at present, although podocarp stands on the young surfaces were probably denser. It is likely that the alpine species with present restricted distribution began to recolonise the central South Island from the northern and southern refugia contemporaneously with the lowland species. Many other more widespread alpine species would have been drawn from the flora of grassland vegetation which occupied the lowlands during glacial maxima. They would have occupied various open habitats during the reforestation of deglaciated areas. In the light of this early reforestation, the failure by some species to complete the colonisation of the central South Island is puzzling. Nothofagus species for example have had ample time to enter this part of the island, since some of them had reached Lake Hawea from the southern refugium somewhat later than 15,000 years B.P. (McKellar 1960) but earlier than about 8000 B.P. Beech species had also reached the upper Waiau-uha River from the north by about 14,100 B.P. (Dr R. P. Suggate pers. comm.). They probably had also colonised the easternmost ranges of Canterbury as far south as the Waimakariri River early in the post-Poulter period.
The explanation of this apparent anomaly is thought to be two subsequent events. The first of these was a renewed ice advance, less extreme than the Poulter advance. By analogy with events in the northern hemisphere and in South America (Flint 1961, Auer 1956, 1958) this short-period stadial, known in New Zealand as the Birch Hill advance, occurred about 10,000-11,000 B.P. The moraines left by it are most evident in the central South Island, and there were probably only cirque glaciers in Nelson and Fiordland. Soon after the Birch Hill ice advance there began a period of cool (upland) to warm (lowland) moist climate known as the ‘climatic optimum’. This effectively prevented further beech advance at the time. Cranwell and von Post (1936) and others have demonstrated how podocarp-broadleaved forest during this time largely superseded beech forest. Beech was, however, present at all times and must have been restricted to higher altitudes and various somewhat extreme habitats. At the fronts with mixed forest in central Westland, the Taramakau and Paringa Rivers, beech species remain limited to the present day by efficient competition chiefly from broadleaved trees such as Quintinia acutifolia and Weinmannia racemosa. The high rainfall occurring in central Westland is an important controlling factor. In headwaters of Canterbury rivers from Mt Cook to the Wilberforce tributary of the Rakaia the upland podocarp forest was maintained in the same way and beech immigration is probably of recent origin. The beech forest front with mixed forest in these valleys is approximately at the position of moraines of presumed Birch Hill
N. menziesii forest, which dominates in Fiordland, supplanted mixed forest (Harris, 1963), probably because of its presence in many places during the ‘climatic optimum’ and because of the local features of cool climate and extremely wet soils to which it is well suited. A renewed glacial advance, probably about 6,500 B.P., may have had some bearing on the subsequent vegetational changes. By analogy with these known situations, other species including some alpine plants could have been restricted by climatic factors.
Some of the discontinuities in populations of ‘partial disjuncts’ and monocentric species which have undergone contraction may have been brought about by the same causes. It is difficult to conceive of any phenomenon so profound that it could cause extinction in the central South Island on the scale described in the opening part of this article later than the last main series of glacial advances of the Pleistocene. The Birch Hill and later advances do not seem to have been intense enough to cause primary disjunction. It seems probable however that post-Poulter climatic changes have inhibited plant migrations from refugia and have also in more recent times brought about contractions in areas. It is probable that subsequent to the period of moist climate with mild temperatures between about 9,000 B.P. and 5,000 B.P. (for dating see Deevy and Flint, 1957) climates began to become at first warmer and then increasingly cooler and drier. Some specific data on distributions of certain plant species support this theory of climatic deterioration probably since about 2,500 B.P. A peat sample from the Grey River valley dated at about 8,300 B.P. (Bowen, ex Grant Taylor and Rafter, 1962) contained Metrosideros robusta pollen (a little south of its present range) and a small amount of Agathis australis (Dr Alseuosmia pollen in a sample from Southland. This sample is presumably from a time equivalent to the above date — during the ‘climatic optimum’. Agathis is not now found south of the Waikato, and Alseuosmia not south of Nelson so that major contractions of area are evident. Some time after about 5,000 B.P. beech pollens begin to supplant podocarp pollens in the peat columns, apparently in a warm, dry period (Cranwell and von Post 1936, Harris 1963). This process was accelerated after about 2,500 B.P. (Deevey and Flint 1957, Harris 1963). Since this time there must have been a decline in temperature and also in rainfall. Changing climate may well be the most important cause of the contractions of many species. Dry, even arid climates seem to be involved in the limitation of species such as Nothofagus menziesii.
Scattered discontinuous distributions of various other widespread species throughout the South Island may have resulted from the same causes of contraction as the examples described above. One cause of many such discontinuities in the eastern South Island, however, undoubtedly is fire during the Maori era (see e.g. Molloy et al. 1963). Subfossil remains demonstrate that forest has been extensively fragmented by fire within the last thousand years. Species dependent on a forest environment are limited by this (see Burrows 1961). Fire is not the only likely cause of discontinuity, nor even the primary one since the evidence for climatic deterioration in the last few thousand years is quite clear. Climatic fluctuations seem to have continued up to the present (Holloway 1954, Wardle 1963b).
Brief consideration of the Auckland-Nelson disjunction (Wardle 1963a) may now be made. During the early Otira Glaciation the southern and central North Island apparently were subjected to severer climatic conditions than was north-west Nelson. The latter area was at the western side of an extensive plain exposed by low sea levels (Fleming 1962). General extinction of forest occurred in the southern half of the North Island although scrub and grassland were present at lower altitudes. During the Poulter stadial beech forest was probably extensive. The question as to whether the tender kauri associate species survived the whole Otira Glaciation in north-west Nelson is still an open one. The influences of Birch Hill cooling have not yet been recognised in this area nor in the North Island. The ‘climatic optimum’ climates would have enabled expansion southward of the kauri associates (and probably kauri itself) so that disjunction of these species may be subsequent to it. Vulcanism in the central North Island (see e.g. Taylor 1953) is almost certainly an important contributor to limitation of many species north of the 38th parallel. Widespread ash showers have probably been as efficient in causing extinction in the centre of the North Island as glaciation in the centre of the South Island, but their invocation as a cause of complete extinction in the whole southern North Island poses various problems. Why did some of the species concerned not survive in the western North Island or near Wellington?
The detailed information presented above supports the general hypothesis of Wardle (1963a) that the Pleistocene glaciation caused extinctions of plants (and animals) in the central South Island and contractions into refugia. In the north, the refugia are likely to have been the coastline and hills of north-west Nelson to the Paparoa range, the coastline of Marlborough and, by virtue of a few plants endemic there, Banks Peninsula. In the south, refugia
As a result of this detailed knowledge of distribution some doubt is cast on the validity of the botanical district concept as framed by Cockayne (1928). On the basis of numbers of endemic species three main floristic areas may be discerned in the South Island (Fig. 8). Each of these contains at least 80 endemic angiosperms. They are: 1. Nelson-Marlborough. 2. Otago-Southland-Stewart Island, 3. An area which overlaps with both of these and runs the length of the island along the mountain chains from Nelson to Southland. There is a concentration of endemics in this latter area mainly east of the main divide and many of
Grateful acknowledgment is made for permission to consult specimens from those responsible for the herbaria of the Canterbury Museum and the Botany Division, D.S.I.R. I have also to thank Mr Pimelea aridula. Several of my colleagues have offered useful criticisms of the script and I express my thanks to them. I am especially grateful to Dr
In Tuatara 12 (3): 155-6, 1964, Trichosurus vulpecula. At first glance this situation may seem inconsequential because no ambiguity is possible if the scientific name is also given. But ‘vernacular’ names of birds and mammals usually have a greater stability than scientific names, and are used by zoologists to a considerable extent. I have placed ‘vernacular’ in quotes because the word implies that a common name is coined by some mead-drinking peasant in the murky past, and arises entirely uncontaminated by scientific research. This might have been true a century ago, but people now identify an animal by referring to books on the subject, most of which are written by zoologists. Zoologists have thus become the originators and arbiters of both scientific and common names. This is inevitable because many birds and mammals have either no true vernacular name or share a name with several other species.
A glance through the scientific papers published on Trichosurus in the last ten years shows that most zoologists (and all Australian zoologists) have used ‘possum’. The reason for this preference is obvious: to use ‘opossum’ for Trichosurus confuses it with Didelphis, and these two genera are as far apart taxonomically as are mice and elephants. ‘Possum’ is common usage in Australia. Mr Kean did not indicate which name he favoured for use in New Zealand but I suggest we conform to international usage. This would standardise the common name and remove the anomaly of two distinct animals sharing one name. In addition, I will be relieved of the embarrassing responsibility of explaining to overseas visitors that we do not have Didelphis in New Zealand (this has happened three times so far) despite what they may have read on the occurrence of the ‘opossum’ in this country.
These views are my own and are not necessarily those of my department.
In this and a following article the New Zealand species of two liverwort genera of importance in elementary teaching are described. The present article considers Lunularia cruciata, and it is suggested that as this species is much more common than the standard textbook example Marchantia, greater use could be made of it in teaching.
In the second article the three species of Marchantia occurring in New Zealand will be described and details given of their occurrence and reproductive cycles.
The Liverwort Genus Lunularia has only one species, L. cruciata (L.) Dum. (Stephani, 1900). It belongs to the Marchantiales and, although showing an intriguing resemblance to Marchantia in its type of gemma, it is in many respects less specialised and is sometimes placed in a family of its own (Hassel de Menendez, 1962).
Although Lunularia was first described from Europe by Micheli in 1729, it is now known to be widely distributed (Frye and Clark, 1937). In many countries it is adventive, for it occurs in greenhouses and in the shaded parts of gardens. Watson (1959) remarks that it is perhaps not a true native of Britain, as it is rare away from habitations. Smith (1955) considers that it was introduced from Europe to U.S.A. with nursery stock and states that, although widely spread in greenhouses throughout the country, only in areas with a mild climate such as California has it become established outdoors.
Lunularia as described in the literature is morphologically uniform throughout its range except in South America. Here, along with forms differing in no respect from those in Europe, there occurs in Chile, Peru and Argentina a type in which the walls of the dorsal epidermal cells are greatly thickened and the ventral surface of the thallus is coloured dark purple. Although this type has been described as a separate species (Herzog, 1938), Hassel de Menendez by maintaining plants in cultivation has shown that the distinctive features become less pronounced. Also at the margin of its range she found plants of intermediate character (Hassel de Menendez, 1962). She considers there is justification for recognition of a form only and names it forma thaxteri (Evans and Herzog) Hassel de Menendez. Writers frequently remark on the fact that sporophytes are very rare. They have been found once at Cape Town (Saxton, 1930), at San Diego, California (Frye and Clark, 1937), at a few places in southwest England
In New Zealand A further finding of both well-developed and mature sporophytes was made at Rangitoto Island in mid-February 1965, and of sporophytes with dehisced capsules by G. A. M. Scott at Dunedin in early February, 1965.Lunularia is abundant at the present time. However, Hooker (1867) makes no mention of its occurrence and, as it seems unlikely that a plant so well-known in Europe would have been overlooked by early collectors, it may be assumed that it has been introduced to this country. It occurs as a troublesome weed of greenhouses and shaded gardens but is also well established as a wild plant amongst native shrub vegetation, in some cases in isolated areas at a distance of up to 20 miles from the nearest farm homestead. Most flourishing colonies were found to form archegonia or antheridia. Sporophytes, however, are not often seen,thaxteri.
The thallus of Lunularia is normally green to yellowish-green in colour, but with age it turns brown, either at the edges or all over. Up to 4 cm, or rarely to 7 cm long, and up to 1 cm, or rarely to 1.8 cm wide, it grows flat on the ground or over existing thalli, often forming extensive colonies as it spreads.
Branching occurs by bifurcation of the apex and, when the latter ceases activity, regenerative growth occurs from adventitious shoots. Above, the thallus often appears somewhat glossy and under a lens can be seen to be marked out into polygonal areas each with a
u in diameter which grow vertically downwards, and narrower, tuberculate ones, 7-24 u in diameter, which near the thallus lie horizontally in bundles and distribute the available water evenly over the lower surface.
On the upper surface of some thalli are groups of disc-shaped gemmae lying in a cupule on the mid-line and protected on the posterior side by a crescent-shaped ridge with a crenate, or in old thalli an almost entire margin (Fig. 1). Each gemma has 2 opposite, lateral growing-points (Fig. 5) and is at first attached by a short stalk, but when mature it becomes detached, floats away in water and under favourable conditions grows into a new plant (Fig. 6). The crescentic cupules containing the gemmae are distinctive of the genus and are responsible for its name.
In structure the thallus shows considerable organisation. In the central portion it is 0.5-1.0 mm in depth and gradually becomes thinner towards the margin. The dorsal epidermis consists of colourless or almost colourless cells; sometimes the walls are thin but often those of centrally placed cells have triangular thickenings known as trigones at the angles and in plants from the open all the walls may be evenly thickened, this being particularly noticeable when the thallus is fresh (Fig. 4). Below the epidermis is the photosynthetic tissue consisting of a single layer of air-chambers separated by green, uniseriate partitions and occupied by numerous, erect, green filaments 3-5 cells high. The air-pores leading into the chambers are elevated above the surface of the thallus (Fig. 2) and are simple in structure, not barrel-shaped as in Marchantia. The compact, ventral tissue is 18-35 cells deep in the midrib region but gradually becomes thinner towards the wings; it is a storage region composed mainly of colourless cells with pitted walls, but scattered cells contain brown oil bodies, and septate fungal hyphae similar to those reported from Lunularia in South Africa (Auret, 1930) may be present in a zone of the midrib region. Fungal infection is sporadic and plays an insignificant role in the life of the plant as has been noted in other countries (Ridler, 1923; Auret, 1930; Nicolas, 1924, 1932). In plants growing in
Marchantia-type initial cells situated at the base of the apical cavity. Although in vertical sections of the vegetative thallus a single wedge-shaped initial cell is apparent, in horizontal sections two similar rectangular cells are usually recognisable, as recorded also for Marchantia planiloba (Burgeff, 1943).
In regard to sexual reproduction Lunularia is dioecious. The antheridial receptacle is a slightly elevated, flat disc 3-4 mm in diameter surrounded by a circular, membranous, cupule-like sheath with a crenate edge (Fig. 1). Originally terminal on one branch of a dichotomy and alternating as to the side of occurrence on the plant, it soon becomes left behind by the onward growth of the thallus and appears to be situated in a lateral position. The antheridia (Fig. 9) are individually sunken in flask-shaped cavities opening to the surface by a simple pore at the end of a canal. In old receptacles the cells adjoining the cavity and the canal tend to turn reddish-purple. Young receptacles were forming in sheltered situations from May until the end of September, at which time most male thalli undergo regenerative growth and produce cupules. Development of the antheridium (Figs. 7 and 8) was found to follow the pattern shown by other members of the Marchantiales, as indeed Saxton (1930) implies, although other interpretations have been given (Chalaud, 1931). The sperm cells are exuded from the mature ovate antheridium in an opaque mucilaginous mass and lie on top of the disc until wetted, when the spermatozoids become free-swimming. Such masses of sperm cells are readily found on plants in the greenhouse and out-of-doors near Palmerston North from mid-July until September. Under conditions of water deficit, however, the antheridia are halted at various stages in development and remain in situ for many months.
The archegoniophore also develops in a terminal position on one branch of a dichotomy but sometimes owing to continued growth of the vegetative branch it becomes left behind in an apparently lateral position. It alternates as to the side of occurrence on the thallus and makes its appearance from May until September with different populations varying as to the starting time. The archegoniophore lies centrally on the floor of a shallow, circular cupule with a crenate rim. For a long time it remains as a
Marchantia species are not present. Development of the archegonium occurs as in other members of the Marchantiales and the mature archegonium is typical of this group (Fig. 10).
Fertilisation takes place readily when spermatozoids are transferred in water by means of a pipette, and on occasions so abundantly that some developing embryos are suppressed. It occurs less readily by natural means both in the greenhouse and out-of-doors near Palmerston North.
The general development of the sporophytes has been described by Saxton (1930). However, from the abundant material available it is possible to add some supplementary notes regarding the early stages. The fertilised egg remains dormant for a period of 4 to 6 weeks though recognisable by its slight increase in size and its denser cytoplasm. Meanwhile both the enclosing calyptra and the archegoniophore are enlarging and accumulating much lipid and protein material. Then suddenly the embryo commences active growth while both the calyptra and the archegoniophore continue their enlargement. The first division in the embryo is transverse (Fig. 11), and this is followed by another transverse division in the upper cell so giving a file of 3 cells (Fig. 12), which by further development produce the foot, the seta and the capsule respectively (Fig. 16). In the foot region a vertical division is followed by further growth and by divisions in various planes until there is produced a massive structure which penetrates through the base of the archegonium into the tissue of the archegoniophore. The seta initial cell divides first by two intersecting vertical walls and then a few times in other planes but active growth and division in this region occurs only when the sporophyte is almost mature. In the capsule region the course of development, as pointed out by Saxton (1930), is of an unusual type. Two intersecting vertical walls give 4 cells each of which now divides transversely (Figs. 13 and 14). The formation of periclinal walls cuts off jacket cells from central cells (Fig. 15). Most of the capsule wall is derived from the jacket cells but the extra layers of the cap region are derived from the upper tier of the central cells. The lower tier of central cells cuts off
When the sporophytes are nearly mature, the stalk of the archegoniophore elongates in just a fortnight to a height of up to 22 mm, so lifting the disc well above the ring of scales (Figs. 3 and 21). At this stage the whole archegoniophore is conspicuous by its general appearance of whiteness, although on close inspection the green foot of the sporophytes is visible within its tissue. The stalk has no rhizoid-furrow and no photosynthetic tissue. It is 1.0 mm in diameter and is more or less shaggy with scattered,
The mature-sporophyte consists of a small green foot, a colourless seta (stalk), and a dark-brown capsule which contains spores together with elaters. It develops within a calyptra and until almost mature is enclosed by the thin involucre. Then on a dry day the involucre unfolds distally to become bilabiate and the seta, which recently has been dividing actively, elongates rapidly to a length of 3 mm, so pushing the capsule beyond the opening (Fig. 3). In several instances there were 2 sporophytes within the one involucre, as was noted also in material from southern England (Saxton, 1930). The capsule is oval in shape and 1 mm long; its wall lacks annular thickenings and is made up of one layer of brown-walled cells except at the top where there is a minute cap 2-3 cells deep of a darker-brown colour (Fig. 17). The ripe capsule opens lengthwise to the base into 4 valves which sometimes begin to divide again lengthwise, but the tiny cap is shed intact. The spores are tetrahedral with a faint tri-radiate marking on the otherwise smooth wall; in colour they are a pale greenish-yellow and in size rather variable with a diameter ranging from 9 to 16 u. The elaters are bispiral, of width up to 10 u and of length 300-430 u, tapering at the ends to a long point. Once the spores are shed the fragile archegoniophore soon collapses.
In order to investigate the germination of the spores these were scattered either on inverted flower-pots filled with sphagnum moss and watered from below with Knop's solution, or in petri dishes on Knop's solution in agar surface-wetted with distilled water. Germination occurs in 10 to 20 days, this being longer than the time given by Chalaud (1932) perhaps due to the fact that the spores dissected from the capsules were not quite mature.
When the spores are well spaced out and the dishes are kept in the light, the course of germination was found to be as follows. The spore enlarges to twice its original diameter and opens in the region of the tri-radiate marking. A colourless rhizoid emerges and is cut off by a wall. The green cell grows rapidly and breaks out of the fragmenting spore coat, dividing first by a more or less vertical wall (Fig. 18), and then each resulting cell dividing both transversely and vertically in a plane at right angles to that of the first division, so giving an octant stage. The sporeling is now approximately spherical in shape but soon becomes irregular when an apical cell arises in one or other of the octants and begins to divide actively (Fig. 20). The apical cell has four faces in contact with neighbouring cells (Fig.
Lunularia as found in New Zealand corresponds with plants described from other countries. Transplant experiments indicate that in New Zealand the form with thin walls in the dorsal epidermis is a shade form developing under glass in greenhouses and in continuous shade outdoors. The form with trigones on the epidermal cells develops under better lighting, either in the open or in hardening-off frames. The form with much-thickened walls is found less commonly, for its requirements of comparatively high light-intensity together with coolness and high humidity are rarely
Fig. 21: Female plant with ripe capsules. Photograph by J. P. Skipworth.
Whereas some colonies near Palmerston North produce sporophytes freely, not all do so. Several reasons can be given to account for their absence. Firstly, some colonies consist of sexually immature or juvenile plants with a thin thallus and scanty food-reserves, for in many instances Lunularia behaves as an opportunist spreading rapidly by vegetative means on disturbed soil, on rock or on brickwork before the arrival of other species. Gemmalings are in this juvenile state for over a year, for even under favourable conditions those formed in autumn and winter do not become sexually mature until the winter or spring of the following year. When plants are damaged by dryness of the air or by extremes of temperature or are disturbed by management practices, re-establishment may occur from gemmae previously lodged amongst the rhizoids or in folds of the thallus, or from adventitious juvenile shoots developing on any still living remnants of the original thallus. Under natural conditions near Palmerston North these latter develop abundantly in late spring and to some extent in autumn. Continued repetition of the regeneration process may produce a colony in which the juvenile state is perpetually maintained.
Secondly, the development of antheridia and archegonia is not always synchronised. Female thalli in late autumn, even when green and fleshy and bearing sporophytes, do not continue apical growth but regenerate from approximately 3 strongly-growing adventitious thalli which, after producing cupules, being to produce archegoniophores at various times from May until September. Even when plants are grown alongside one another in the greenhouse, different populations vary as to when they start to form archegoniophores; and in the open the growth in almost all populations is liable to be checked at any time by unfavourable weather. Male plants behave differently as, even when dried out, they often grow again from the resistant apex once the rains commence in late autumn. New antheridiophores arise and old ones revive and continue development but as with the female plants growth may be halted at any time by unfavourable weather. Where, however, the male plants die off in autumn and regenerative growth occurs, the new thalli at first resemble gemmalings and grow very slowly; only in the greenhouse were they sufficiently advanced to form antheridiophores late in the season. In the open they develop so slowly as compared with female plants that the population under these conditions appears to consist solely of female plants. Populations entirely or predominantly of female plants have been noted also in other
Provided sexually mature male and female plants are growing intermixed, fertilisation was found to occur quite readily. However, the sporophyte takes several months to mature and, since its delicate coverings are inadequate for protection from drying winds, few survive to maturity. In an unheated propagating pit in the greenhouse the sporophytes developed satisfactorily.
Recent experimental work with the Israeli strain of Lunularia has demonstrated a response to photoperiod (Nachmony-Bascomb and Schwabe, 1963; Schwabe and Nachmony-Bascomb, 1963; Wilson and Schwabe, 1964). However, any interpretation of the behaviour of the New Zealand plants in the light of these findings is complicated by the fact that winter temperatures in New Zealand are much lower than any used in the experimental work.