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THE NEW ZEALAND ONYCHOPHORA

By. J. C. Watt

INTRODUCTION

The Phylum Onychophora includes animals popularly known as Peripatus. These are of extraordinary interest in that they occupy a position between the phyla Annelida and Arthropoda. They are elongated, caterpillar-like animals with from 14-42 pairs of clawed legs, and with a poorly defined head bearing a pair of antennae, a pair of jaws, and a pair of oral papillae, the two latter structures being obviously modified legs. The skin is soft and velvety, and bears numerous small papillae with small spines. There is no external trace of segmentation apart from the segmental appendages, and the limbs are not jointed.

DISTRIBUTION AND SYSTEMATICS

The Onychophora have a discontinuous southern distribution, occurring in South Africa, Australasia, New Guinea, Indonesia, Malaya, Tibet, New Zealand, South and Central America. This type of distribution indicates that the group is probably of considerable antiquity. Fossil Onychophora are known from Cambrian marine rocks, and there is a fossil from Precambrian rocks that may have been an extremely primitive member of the group (Wenzel, 1950).

There are about 70 species, now grouped into 11 genera, although all known forms were previously included in a single genus Peripatus (refer Sedgwick, 1888; Bouvier, 1900). The New Zealand genera are Peripatoides Bouvier aid Ooperipatus Dendy, species of both also occurring in Australia. Peripatoides novaezealandiae (Hutton, 1876) is the common "Peripatus" of the North Island and is found near Auckland. A species of Ooperipatus occurs on Rangitoto Island.

KEY TO THE NEW ZEALAND ONYCHOPHORA

The description given in the Introduction will suffice to

-96-distinguish the Onychophora from all other New Zealand terrestrial animals. They resemble caterpillars super­ficially, but these never have more than three pairs of clawed legs, always have a clearly defined head, segmentation is generally fairly obvious externally, and there are other differences - more or less obvious to the naked eye.

1. Oviparous species, female with a muscular ovipositor between the posterior pair of legs^eggs large with a hard sculptured chorion, with 14 pairs of clawed legs (N. B. oral papillae are not legs) « colour brown with dorso-laterally on each side a row of green spots opposite each leg, and dark brown longitudinal and transverse markings somewhat variable (colour pattern differs from this in Rangitoto Island specimen).

- - - Ooperipatus viridimaculatus Dendy (1902) (Vicinity of Lakes Whakatipu and Te Anau; Nelson? Rangitoto Island?)

Viviparous species, female lacking a muscular ovipositor, egg (not laid) with soft transparent chorion, with 15 or 16 pairs of clawed legs, colour bluish green or bluish grey, generally with numerous small cream-coloured spots Peripatoides -2

2. With 15 pairs of clawed legs

- Peripatoides novaezealandiae (Hutton, 1876) (North Island and northern South Island. )

With 16 pairs of clawed legs P. suteri (Dendy, 1894)

(Vicinity of Mount Egmont; Epsom. )

Ooperipatus viridimaculatus Dendy (1902)

Material examined: Pearl Flat, Matukituki Valley, near Lake Whakatipu, under logs near stream, A. J. Sinclair. 2 ^ specimens in coll. R. W. Taylor L Length 24 m. m., greatest width 5 m. m. (after preservation).

Rangitoto Island, E. Allen, 31. 7. 32. 1 ̂ specimen in coll. Auckland Museum. This specimen has the typical muscular ovipositor and 14 pairs of clawed walking legs. Although apparently mature it is much smaller than the South Island specimens (9 m. m. long and 1. 7 m. m. wide after preservation. It differs also in coloration, the dorsal surface being a much darker brown, the green spots

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J. C. Watt Collection: Waipoua Forest (1) Kohukohunui, Hunua Ranges, ca 1500 ft (1) moana (2); Mount Hikurangi, 3, 500 ft (2)

Clevedon (2); Lake Waikare-Wellington(2).

R. W. Taylor Collection: Cascades, Waitakere Ranges (12); National Park, ca 3, 500 ft (2); Eketahuna (ca 20);

Auckland Museum Collection: Kaeo (1); Paihia (1); Hen Island (1); Titirangi (8); Auckland Domain (1); Moumoukai Valley, Hunua Ranges (3); Waiuku (1); Huia (1); Tryphena, Great Barrier Island (2); Waikauri (1); Awamarino (1); Katikati (1); Kakapi (1); Parikanapa, Gisborne, 1800 ft (1); Mount Burnett, Collingwood, 2, 000 ft (1).

The specimens vary considerably with regard to colour, and size of apparently mature specimens. The latter may well be largely dependent on nutrition. All have 15 pairs, of legs and all appear to be referable to a single species if that is regarded as highly variable.

Distribution: North Island and northern South Island.

being entirely absent, and the dark brown markings differ in pattern and are not clearly defined. The coloration of the undersurface also differs from that of the South Island specimens. As it is an unique specimen and fresh material should be readily available from the same locality, the structure of the mandibles and other parts requiring dissection have not been investigated. Nelson - Havelock Rd,, X moss, 11. 12. 57., J. G. Pendergrast. 1 specimen, which is similar to the Rangitoto Island form in size and coloration.

Other Records (Dendy, 1902): Clinton Valley, head of Lake Te Anau (Types).

? Te Aroha - 5 specimens recorded by Fletcher (1900) with 14 pairs of legs but without green spots.

Peripatoides novaezealandiae (Hutton, 1876)

Material examined: (No. of Specimens in brackets following locality).

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Peripatoides suteri (Dendy, 1894)

Material examined: Mount Egmont, ca 4, 000 ft, 1 specimen, in pool on track between North Egmont and Bells Falls, in coll. J. D. Fawcett. Mount Egmont, January, 1939, L. M. C. (1); Epsom, 19. 7. 32, M. Buckland (2 specimens) (Auckland Museum Ck)ll J.

Other records: (Dendy, 1894) Stratford, 3 specimens.

ECOLOGY

This account is based on the records of Hutton (1876, 1877, 1878, Dendy (1902), and on notes by the writer and other collectors mention­ed above.

All species are cryptozoic, inhabiting moist sheltered places. They are perhaps most commonly found in rotten logs, or clinging to the underside of rotten logs, but also occur under stones, in damp rock crevices, in leaf litter, in moss, and under matted subalpine vegetation. They are undoubtedly mainly nocturnal, although Hutton states that P. novaezealandiae will feed during the daytime if hungry.

During the winter, P. novaezealandiae is much less active than during the warmer months of the year in the vicinity of Auckland. In the colder parts of New Zealand they apparently hibernate (Hutton, 1877).

P. novaezealandiae feeds on small terrestrial animals, probably mainly arthropods inhabiting rotten wood. A viscous secretion of slime produced in slime glands is shot out from the oral papillae and used to entangle prey. Hutton observed a specimen capture a housefly in this way, it "then went up and sucked its (the fly's) juices, rejecting the whole of the integument". Thus the slime is apparently used for offensive rather than defensive purposes.

Moisture appears to be the chief factor limiting the distri­bution of the New Zealand Onychophora. The soft cuticle affords no protection against prolonged desiccation, precluding their existence in habitats subject to even occasional pronounced drying. Hence they are absent from such regions as the Canterbury Plains. They will apparently survive in pasture land only when it is

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fairly moist and there is plenty of cover in the form of lota or stones.

It will be clear from the above account that knowledge of the ecology of the New Zealand Onychophora is limited to general observations of the biology, mainly of P. novaezealandiae. The other species no doubt resemble the latter ecologically in general features, but will probably be found to differ in details.

a n a t o m y '

The anatomy of Onychophora is relatively constant in its major features. P. novaezealandiae differs from most Onychophora, including Ooperipatus, and the Australian species of Peripatoides. in the absence of crural glands in the male. A brief account of the anatomy of 0. viridimaculatus is given by Dendy (1902), while certain features of the anatomy of P, novaezealandiae are covered by Sedgwick (1888) and Sheldon 1888, b). According to Dendy (1894) the anatomy of P. suteri is very similar to that of P. novaezealandiae. For further details of onychophoran anatomy refer Cuenot (1949.

., EMBRYOLOGY. ̂ J'

The development of P. novaezealandiae is described in considerable detail by Sheldon (1888, a), while Dendy (1902) gives a relatively brief account of the development of 0. viridimaculatus.

In P. novaezealandiae the egg is large and heavily-yolked, and cleavage is superficial. Development takes place within the uterus of the mother, but there is no placenta formed as in some other Onychophora. Specimens of P. novae­zealandiae examined by Sedgwick (1886) led him to conclude that eggs pass into the uterus from the ovaries in November and December, and that young are born in July, thus undergoing a gestation period of eight or nine months. This conclusion, as he points out, was not supported by observations of Hutton (1878).

In both Australian and New Zealand species of Ooperipatus the eggs are heavily yolked with a thick sculptured chorion, and when laid show no sign of a developing embryo. An egg of O. oviparus from Victoria took seventeen months after

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oviposition to hatch. It is not known for certain where or at what time of the year Q. viridimaculatus lays its eggs. Dendy (1902) found that oviposition took place in autumn on rotten wood in captivity.

PHYLOGENY

Dendy (1902) regards oviparity in the Australasian species as more primitive than viviparity, even if the oviparous species originally evolved from viviparous species. Thus he regards Peripatoides as a genus derived from an oviparous type, i, e. a primitive form of Ooperipatus, in Cretaceous or pre-Cretaceous times. The latter qualification is necessary, in order to explain the occurrence of Peripatoides and Ooperipatus on both sides of the Tasman Sea.

This theory requires critical re-examination, as the present writer can see no reason why, on the evidence stated by Dendy, a viviparous form should not have given rise to Ooperipatus in or before Cretaceous times. Evolution is not irreversible, but to regard Ooperipatus as more primitive either means that it is a direct descendant from an oviparous ancestor of all living Onychophora, or that evolution has reversed its direction three times in the derivation of peripatoides from an Ooperipatus whose ancestor was viviparous.

PROBLEMS REQUIRING SOLUTION There is much further research yet needed on the New

Zealand Onychophora before our knowledge of then can be said to be adequate. Most zoologists with whom the writer has discussed the New Zealand. Onychophora were not aware that this country possesses an oviparous species.

The following are some of the problems still requiring solution, several of which could well be investigated by Field Club members and other interested amateurs.

1. In neotropical Onychophora, the numbers of pairs of legs varies within species. Is P, suteri purely a variety of P. novaezealandiae, or does it represent a full species? All specimens of Onychophora seen, especially on Mount Egmont and near Auckland, should

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be examined, and the number of legs counted. This does not mean that it is necessarily desirable to preserve every specimen found in each locality, as two or three will be sufficient if all are obviously P. novaezealandiae, and the remainder may be liberated. Specimens may be preserved in 70% alcohol with a little glycerine to prevent undue hardening. They should be anaesthetised first with ethyl acetate or some similar volatile liquid, but preferably not chloroform which causes hardening and may cause discolour­ation. If necessary they may be placed direct in 70% alcohol without undergoing irreparable harm. Field examination of all specimens seen, and collection of a few from each locality will assist mapping the distribution of the species in detail. A special watch should be kept for Ooperipatus, particularly in the North Island, as study of further North Island specimens is necessary to determine the systematic status of the latter.

2. No detailed comparative study of the anatomy of the New Zealand Onychophora has been undertaken. Such a study may aid in clarification of the systematic status of the various populations of both Peripatoides and Ooperipatus. and the genera themselves.

3. Contributions to knowledge of the ecology of the New Zealand Onychophora may be made by careful observation of the animals in their own habitat, and by keeping specimens in captivity. They will live quite happily in rotten wood, provided it is kept moist and they are supplied with food. In particular a special search should be made for Ooperipatus on Rangitoto Island, as nothing is known of the ecology of these animals from this locality.

4. When are the eggs of Peripatoides normally released from the ovary; when, and under what conditions does fertilisa­tion take place; and what is the normal. gestation period?

5. In Ooperipatus, when and under what conditions does fertilisation take place; when and where are the eggs laid in nature?

6. Various physiological aspects of Peripatopsis capensis and other foreign species have been studied (e. g. Manton, 1953; Bursell and Ewer, 1950), but no research of this

-loa-kind has been done on the New Zealand Onychophora. As P. novaezealandiae is easy to keep in captivity it would probably lend it self to this type of investigation.

ACKNOWLEDGEMENTS

I wish to thank Dr G. Archey, Director, Auckland Institute and Museum, for the opportunity to examine the Onychophora in the Museum, Mr. RlW. Taylor for the loan of a very interesting collection, Mr. E. N. Milligan for gift of a specimen form Waipoua Forest Mr J. D. Fawcett for loan of a specimen of P. suteri, Dr J. G. Pendergrast for loan of a specimen of Ooperipatus, and Mr. D. A. Challis for information concerning keeping Peripatoides in captivity.

REFERENCES Bouvier, M. E. L., 1900: Quelques Observations sur les ^

Onychophores (Peripatus) de la Collection du Musee Britanique, Q. J. M. S. 43: 367-373'

Bursell, E. and D. W. Ewer, 1950: On the Reactions to Humidity of Peripatopisis moseleyi (Wood-Mason). J. Expt. Boil. 26: 335-353.

Cuenot, L., 1949: Less Onchophores, Traite de Zoologie 6: 3-37, Masson et Cie., Paris.

Dendy, A., 1894: Note on a New Variety of Peripatus novaezealandiae Hutton, Trans. N. Z. Inst. 27: 190-91.

1902: On the Oviparous Species of Onychophora, Q. J. M. S. 45: 363-415.

Fletcher, J J. 1900: Note on a New Zealand Peripatus, Proc. Linn. Soc. N. S. W. 25: 116.

Hutton, F. W. 1876: On Peripatus novaezealandiae, Ann. Mag. Nat. Hist. (4) 18: 361-69.

1877: On Peripatus novaezealandiae, Ann, Mag. Nat. Hist, (4) 20: 81-83.

1878: On Peripatus novaezealandiae, Ann, Mag., Nat. Hist. (5) 1: 204-6

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1890: The Maturation of the Ovum in the Cape and New Zealand Species of Peripatus, Q. J. M. S. (not seen by present

., author)..,,, • ̂ ,̂., ̂

Wenzel, R. L., 1 9 5 0 : Peripatus, "Living Fossil" and "Missing Link' Tuatara 3: 98-99.

Manton S. M., 1953: Locomotory Habits and the Evolution of the larger Arthropodan Groups, Symp. Soc. Exp. Biol. 7: 339-376

Sedgwick, A., 1888: A Monograph on the Species and Distribution of the Genus Peripatus Guilding, Q. J. M. S. 28: 456-463.

Sheldon, L., 1888, a: On the Development of Peripatus novae­zealandiae. Q. J. M. S. 28: 202-237.

1888, b: Notes on the Anatomy of Peripatus capensis and P. novaezealandiae, Q. J. M. S. 28: 495-99.