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Historical Introduction
To A. S. Thomson, surgeon to the 58th Regiment, belongs the distinction of having written the first account of the New Zealand native frog (Thomson, 1853, 66). In October, 1852, gold was found in the hills surrounding Coromandel Harbour During the following month, Thomson visited the area and watched prospectors washing the soil of a mountain stream. During their excavations they displaced a number of boulders, under one of which they found a frog. Amid general excitement the unfortunate animal was placed by the men in a tightly-corked bottle, in which it soon died. It was then given to Thomson, who took it with him to a conference at which Lieutenant-Governor Wynyard was negotiating for gold-digging rights with the chiefs of local Maori tribes. The appearance of the frog greatly surprised the Maoris who, according to Thomson, had no word for it in their vocabulary. They regarded it with very great awe as being possibly the spirit or god of the gold. Later, three more frogs were found in another stream. One of these was lost and the Maoris insisted on the release of the other two in case supernatural vengeance should descend on the collectors.
Although Thomson described the frog he did not name it. From his description it was clearly a specimen of what is now known as Leiopelma hochstetteri.
The name Leiopelma was provided by Fitzinger (1861), who described two male frogs, both of the same species. These were collected from the Coromandel peninsula by the Austrian naturalist, Hochstetter, who had visited New Zealand during the course of his voyage in the frigate “Novara”. Fitzinger apparently had not read Thomson's paper: at least he made no comment on it. He regarded Leiopelma hochstetteri as being more closely related to Telmatobius peruvianus Wiegman—classed by Noble (1931, 499) as a bufonid—than to any other anuran then known. He placed the genus among the true “water frogs”. A translation of Fitzinger's Latin diagnosis of the genus and species is given below. The rest of his detailed description has been summarised by a later author (Steindachner, 1869).
Character of Genus. Transverse processes of the sternum dilated. Parotoid glands absent. The soles of the feet devoid of hard pads and the joints of the fingers devoid of swellings. Fingers free, toes half-webbed. Males devoid of vocal sacs. Tongue free behind and a perfect oval.
L. hochstetteri: Ashy-black, spotted below with white; the thighs speckled with white ventrally; dorsal surface of the thighs, tibiae and feet faintly banded with black; a white spot on each side of the palms of the hands and also beneath the inside digit of the foot.
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It seems curious that Fitzinger should have mentioned a dilation of the sacral diapophyses. Compared with those of most anurans these structures in Leiopelma show only a slight distal flattening and dilation.
Fitzinger's account makes it quite clear that the two frogs were found in water and that the only known locality was “the neighbourhood of the Coromandel Harbour on the East side of the Hauraki Gulf.” The frogs were collected for Hochstetter by the Maoris who, surprisingly enough, appeared to have overcome their initial fear. They were employed in panning for gold in “small creeks which spring from the Cape Colville Mountains and flow to the sea.”
Fitzinger mentioned that one specimen of Leiopelma was in the British Museum at the time of publication of his paper in 1861. This specimen could either have been one of Hochstetter's two or, more likely, Thomson's original frog, which reached James Thomson, Esq., Glendoman, in 1853. The amphibian catalogue at the British Museum, however, states that a specimen of Leiopelma was first acquired in 1865, and that it was presented by “Sir A. Smith”. Through the courtesy of the Natural History Museum authorities E. M. Stephenson was permitted to examine this specimen in 1948, and was interested to find that the spelling of the name on the label was Liopelma. This spelling has been attributed to Günther (Turbott, 1942, 247) who, in 1868, published a short list of anurans added to the collection of the British Museum after 1858. Whatever the history of this particular specimen, Fitzinger's published name for the genus clearly predated that of Günther and the original spelling should be retained (Turbott, 1942, 247).
In 1867, Hochstetter's own book on New Zealand appeared. A short paragraph in this emphasises the uniqueness of this frog, its rarity, and the fact that it was known to frequent only creeks and swamps of the Cape Colville Range. He accepted Fitzinger's classification.
The year 1869 brought the publication of “Reise der Fregatte Novara. Zoologischer Theil.” by Steindachner. Leiopelma was not included amongst the many amphibian illustrations but was, however, reclassified by Steindachner and placed in the family Bombinatoridae. Steindachner also altered and improved Fitzinger's generic description and summarised the account of the specific characters. Hutton (1879) translated Steindachner's description In the account of the specific characters one reads “external nostrils rather nearer to the eye than to end of muzzle”. Compare this, however, with Fitzinger's original “Die Nasenlocher liegen genau in der Mitte zwischen den Augen und dem Schnauzenende”.
In 1870, A. W. Aitken published a brief account of his finding of a frog in a range creek running through the Thames gold-field, near Puriri, at a height of at least 500 feet above sea-level. He did not describe the animal, but from its location it was presumably L. hochstetteri Fitzinger. Aitken's original specimen was sent to the Auckland Branch of the New Zealand Institute, but is apparently not in the Auckland Museum (Turbott, 1942, 251).
The first discovery by a European of frogs on the hills, out of water, was made by S. Percy Smith, in 1862, but his findings were not recorded until 1921. The frogs were found under moss-covered stones on the crest of the main Coromandel Divide, and were described as being green and golden-brown in colour and about an inch long. As will be seen later, they belong to a subsequently described species, L. archeyi Turbott.
In 1889, George Graham was shown native frogs on “the ridges of the Moehau ranges” by a Maori. Graham did not publish his observations until 1924, and then only as a note in a paper by John White on the Patu-paiarehe. According to Graham's Maori guide, the frogs of Moehau were incorporated in local legend as the sentries of the mysterious Patu-paiarehe.
In 1898, McClaren published an account of the geology of Mt. Moehau. He mentioned Leiopelma and spoke of “. its singular mode of progression, its colour, and finally its many attitudes, so grotesquely human.…”
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In 1919, McCulloch recorded the finding of a new species, Leiopelma hamiltoni McCulloch, on Stephens Island, in Cook Strait. The animal was clearly terrestrial, had only a faint trace of a web, and was patterned in green and brown. McCulloch placed the genus in the family Discoglossidae.
The first published account of the development of any species of Leiopelma was written by Archey (1922). He visited the Tokatea ridge, a few miles north-east of the Coromandel township, during the breeding season (October-December) and collected eggs and frogs from under logs on the ridge, well away from surface water. Back in Auckland he watched the direct, intracapsular development of the embryos under a binocular microscope, and managed to keep a few specimens alive until they hatched. He also carried out a significant experiment (N. G. Stephenson, 1951 b, 20) by releasing one embryo from its capsule and allowing it to develop for some days in water. His valuable account dealt with external features only.
Turbott (1942) was the first to recognise that the terrestrial frogs from Tokatea, which had been collected by Archey and which apparently resembled those recorded by Smith (1921) and Graham (1924), belonged to a third species of Leiopelma which he named Leiopelma archeyi. He published a diagnosis of this species and a key separating the three species of Leiopelma. He also summarised what was known of the distribution of the frog.
Observations up to the time of publication of Turbott's paper had indicated that L. hochstetteri Fitzinger was dependent on the presence of surface water and was typically found only in streams, while L. archeyi Turbott was confined to adjacent ridges and hill tops. In other words, a material barrier was thought to exist between the two species at least in the breeding season when conditions are possibly fairly dry.
Field observations by Stephenson and Thomas (1945) showed that the idea of a material barrier required qualification. During December, 1944, they found a specimen of L. archeyi and a specimen of L. hochstetteri, both females, under the same stone on the Tokatea ridge, well away from surface water. This close mingling of the two species was observed on other occasions also by the same authors, and it is now known that L. hochstetteri can be found at appreciable distances from streams. L. archeyi, on the other hand, has been found actually in stream water (Turbott, 1949). Vivarium specimens of L. archeyi, if provided with a pool of water, will often choose to sit in it (authors' observation). The existence of a material barrier of any geographical kind does not therefore hold, although the two species presumably have some type of mating barrier. They appear to be true sympatric species (Mayr, 1942) on the Coromandel Peninsula. In other regions, e.g., Huia, Warkworth and Karekare, L. hochstetteri occurs alone (Fig. 1, p. 871).
Stephenson and Thomas (1945) also showed that the maximum body length proposed in Turbott's key (1942) was inadequate for L. archeyi Turbott, and that the majority of specimens found by them at Tokatea exceeded this. L. archeyi may reach a size of 41 mm, and 39 mm to 40 mm is not uncommon. An alternative key is published in another section of this paper.
In November, 1946, N. G. Stephenson collected several egg clusters of L. archeyi from under stumps or logs on the sphagnum bog near the summit of Mt. Moehau, on the eastern aspect. He watched them develop under laboratory conditions, killing and fixing specimens at regular intervals, from intracapsular embryos to post-hatching stages, when the tail is reduced and adult proportions attained. Stephenson was able to make comparisons of the development of Leiopelma archeyi with that of Ascaphus truei and with amphibians having direct development (N. G. Stephenson, 1951b). He was also able to suggest an approximate time length for the entire developmental period. At that time, nothing was known of the life history of L. hochstetteri and L. hamiltoni.
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In 1947, the authors were given permission by the Hon. Minister of Internal Affairs, Wellington, to collect a certain number of frogs for study in London. For this purpose specimens of both L. archeyi and L. hochstetteri were taken from Tokatea, Coromandel, and transported by ship, without any casualties, to England. The frogs were kept in damp moss inside large jars, and were housed in an anteroom to a main refrigerating chamber. En route they were fed on house-flies, and arrived in London in excellent condition. Most of them were eventually killed and used for anatomical study, but a few were kept alive in the Zoology Department, University College, London. They were eventually left in the care of the Curator of Reptiles and Amphibia at Regent's Park Zoo.
In captivity, the frogs showed no inclination to breed, and after a time several attempts were made to induce ovulation, and possibly amplexus, artificially. These attempts to induce ovulation were successful and, as described in a later section, four batches of eggs were laid. This is the first record of Leiopelma eggs laid in captivity. Unfortunately all were infertile. Amplexus was not observed, nor has this been recorded so far in the field.
A detailed study of the adult cranial characters of L. archeyi and L. hochstetteri (Elsie M. Stephenson, 1951) showed conclusively that at least eight constant, specific differences exist in these characters alone.
In 1949, the question whether L. hochstetteri had direct development or whether it possessed an aquatic tadpole stage, was solved by Mr. S. Gittos, of Warkworth (Turbott, 1949). Mr. Gittos found egg capsules containing embryos in “wet mud of a seepage or spring” on his property on the slopes beneath the peak known as the “Dome”, a locality in which he had been observing the frogs over a period of some years. In November, 1949, Mr. E. G. Turbott, of the Auckland War Memorial Museum, accompanied Mr. Gittos to another forest-covered seepage, and found frogs and eggs in wet clay. Some were in tunnels made by dragonfly nymphs (Turbott, 1949, 375). The development of L. hochstetteri has since been described by N. G. Stephenson (1955) to whom these eggs were given by Mr. Turbott. Stephenson was able to show that eggs separated from the same cluster would undergo their intracapsular development equally well when immersed in water, as when placed in damp terrestrial situations.
Since McCulloch's publication in 1919, little had been heard of L. hamiltoni McCulloch on Stephens Island, Cook Strait. Occasional specimens were found up to 1942 (Dawbin, 1950, 830), but from that time until 1950 even repeated searches for the frogs failed to locate them. It was concluded that the disappearance of the bush and the subsequent drying out due to strong winds and sunlight had caused the extinction of this species. The frogs had always been confined to a boulder bank at the top of the island, a region which by 1950 had lost its forest cover. Early that year, however, Mr. W. H. Dawbin, of Victoria University College, and Mr. R. Dawbin, found one frog. In May of the same year, five more were found, which were photographed and released. A few more specimens have been found by Mr. W. H. Dawbin on occasions since then. At the present time, no direct observations of developmental stages of L. hamiltoni have been made. Since no surface water occurs on the boulder bank, an intracapsular mode of development undoubtedly proceeds under sufficiently damp terrestrial conditions—probably deep under the boulders.
By permission of the Hon. Minister for Internal Affairs, and through the kindness of Mr. W. H. Dawbin, E. M. Stephenson was given a specimen of L. hamiltoni in 1951, and later (1955) published an account of the cranial characters. L. hamiltoni resembles L. archeyi in many external characters, particularly in colouring, absence of a web, and presence of parotoid glands. It also resembles L. archeyi in five out of the eight cranial characters mentioned above as distinguishing L. archeyi and L. hochstetteri.