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A KEY TO THE VARIOUS CLASSES OF TERRESTRIAL ARTHROPODA.

by Maureen H. Barclay

Note: This article is designed to enable students who are beginning studies of terrestrial ecology to recognize the various classes of terrestrial represented, basing their identification on external characters. For this reason it is necessarily elementary, dealing with distinctions which will be known by advanced students of Zoology. However, for their benefit, and for those others wishing to proceed further to actual specific identification, a list of references appears at the end of this article.

By definition, the arthropods are segmented, bilaterally symmetrical , with paired limbs, at least one pair of which function as jaws. They have a chitinous cuticle which is usually rigid, yet provided with joints to allow movements of body and limbs.

A Key to the Classes of Terrestrial Arthropods

1 (a) Cuticle soft and thin, without joints. Body wall soft and muscular. Three segmented head not marked off from body and remaining segments all alike . •. Class ONYCOPHORA (b) Cuticle and body form otherwise (2) 2 (a) First appendage chelicerate, not antennate ... C lass ARACHNIDA (b) First appendage antennate (3) 3 (a) Two pairs of antennae present •.. Class CRUSTACEA (b) One pair of antennae only (4) 4 (a) Three pairs of walking legs present ... Class INSECTA (b) Many pairs of walking legs ("Myriapods") (5) 5 (a) Genital opening at hind end of body ... Class CHILOPODA (b) Genital opening on third segment behind head (6) 6 (a) Antennae short ... Class DIPLOPODA (b) Antennae long and many jointed •.. Class SYMPHYLA

ONYCOPHORA

Only in this class does the first somite bear a pair of limbs. All the legs are short, not truly jointed but transversely ringed. At the distal end of each is a retractile, terminal foot with two recurved claws. The head bears three appendages; a pair of pre- antennae which are long and mobile, but irretractible, a pair of small, oral papillae, and the jaws, borne on muscular papillae within the oral cavity.

These caterpillar-like animals have an interesting protective adaptation - the ability to squirt a sticky, slime-like secretion that entangles their enemies. FIG. 1 Peripatoides. FIG. 2 A Pseudoscorpion.

FIG. A An Orb web. FIG. 5 Dolomedes.

FIG. 3 Araneus.

FIG. 7 A Phalangid.

FIG. 6 Trite.

FIG. 9 An Oribatid mite. Drawings not to scale FIG. 9 A Trombidiid mite. 11 -

Onycophora are restricted to moist environments. They generally avoid light and live in rotten logs, under loose bark, in moss, etc., where they feed on small insects and other micro-organisms. The common example, Peripatoides novaezelandiae (Fig. l) is a velvety- greygreen with fifteen pairs of legs. It may reach up to two inches in length.

ARACHNIDA

In the the anterior part of the body (prosoma) is never divided into a head and thorax. The first appendages are prehensile (chelicerae), the second prehensile or sensory (pedipalps) and the remaining four ambulatory. These animals feed on liquids extracted from their prey by way of a pharyngeal sucking pump.

Within this Class come:

Order Pseudoscorpionidea - small (2-4mm. ), scorpion-like Arachnids but with no tail. The pedipalps are large and strongly chelate (see Fig. 2). The abdomen is broadly joined at the thorax; it is wide, flat and usually comprises eleven segments. They are usually encountered in leaf litter on the forest floor and it is thought that they feed chiefly on mites and small insects.

Order Araneida () - Arachnids with the prosoma covered by a single shield, the head being marked off by a groove. The abdomen is separated by a waist. It is soft and only rarely shows any signs of external segmentation. Spinning glands are present on the abdomen. In a typical the prosoma is relatively small and depressed as compared with the rotund abdomen. It carries the chelicerae, pedipalps and four pairs of legs. Most spiders have eight eyes, distributed across the central part of the prosomal shield. This number, however, may be reduced and the number, position and relative size of the eyes serve as diagnostic characters for classification.

The. -a are many different spider families, the animals occupying a number of different types of habitat, trapping their prey in numerous different ways.

The family Argiopidae comprises the orb-weavers. These are most easily recognized by their well known web composed of slender lines radiating from a central point or hub, like the spokes of a wheel (Fig. 4). The common N. Z. is Araneus, A. crassus being often encountered (Fig. 3).

The family Lycosidae (wolf spiders) contains hunting spiders which chase their prey. These velvety animals run through the undergrowth or lurk under stones, especially in damp situations. Many dig tunnels. They all carry their large egg sac attached to the spinnerets by a bundle of threads and the young, when hatched, climb on to the female's back and are carried around by her. FIG 11. An Harpacticoid.

FIG. lO, 1Oa Mesocypris.

PIG. 12 An Isopod, P^siiis scaber. FIG. 13 An Amphipod.

FIG. M A Geophilid Centipede. FIG. 15 A Scolopendrid Centipede.

FIG. 16 A Millipede. FIG 17 A Symphylan Drawings not to scale. - 13 -

Great maternal devotion is found amongst the family Pisauridae - the nursery-web weavers (e. g., Dolcmedes minor (Fig. 5) ). The female carries the egg sac about with her until the young are ready to emerge, when she then fastens it to leaves at the tip of some shrub or other plant and builds a nursery around it by fastening the leaves together with a network of threads.

Included within the family Dipluridae is the large Hexathele, a genus which builds a web tube under stones, in banks or in the bark of trees. Porrhothele is another genus with similar web-building habits while Migas builds a typical trap-door nest in the same type of habitat.

The agile "jumping" spiders belong to the family Salticidae. They are the only spiders with the ability to leap, the propulsion being provided by the hind legs. They are medium or small spiders with a short body and stout legs, and are often brightly coloured. They may be found almost everywhere - on bushes, rocks, etc., especially in places warmed by the sun. Trite (Fig. 6) is a relatively large local example.

Order Opiliones or Phalangida (Harvestmen). These can usually be recog• nized by their very long and slender legs (Fig, 7). The carapace is indistinctly, if at all, segmented. The abdomen is not constricted off from the cephalothorax and is short and broad, and the legs are long and slender, only the coxae being stout. Although stilt-like in appearance harvestmen do not raise the body much above the ground when they walk, but carry it low down, with the middle part of the legs high in the air. When disturbed they stand on six legs and move the second pair about in the air.

These animals are more characteristic of open fields than dense bush.

Order Acarina (Mites and Ticks). This order is characterised by an unsegmented abdomen which is not constricted at the base, but broadly joined to the cephalothorax, with little or no indication of a division between these two regions. The body often presents a sac-like appear nee. Normally there are six pairs of appendages - the chelicerae, pediparps and four pairs of legs. The chelicerae may be chelate or needle-like, in the latter condition being adapted for piercing. The pedipalps vary greatly in size, form and function and may be used for tactile purposes, predation (when they are armed with spines, hooks or claws), or clinging, when they take on a chelate form. As a rule, they average l-2mm. in length.

Free-living, terrestrial mites occur in practically all situations where vegetation is found, being located amongst the decaying debris and in association with mosses and lichen. In the moss and leaf litter of the bush they may often form 70-80% or more of the total animal population. Many feed on decaying plant remains, others scavenge for decaying animal remains, while many are predatory, feeding on other small arthropods, particularly Collembola, the eggs and larvae of small insects and small Oligochaetes. - 14 -

The dark, heavily sclerotised Oribatei are commonly encountered, these usually being found in large numbers in moss, humus and soft vegetation. The type figured belongs to a family which can fold the legs and head into the main body capsule for protection.

Within the Trombidiformes, the subfamily Trombidiinae of the family Trombidiidae contains some large, bright red mites. These animals are covered with velvety, plush-like hairs. The legs are adapted for crawling or running, and the palpi are raptorial (Fig. 9).

CRUSTACEA

The crustacean cuticle is usually stout, and often strengthened by calcification. The head bears five pairs of appendages: two pairs of antennae, mandibles, maxillules and maxillae. Many of them have developed a carapace - a dorsal fold of cuticle arising from the hinder border of the head and extending over the trunk. Its size varies greatly. In the Ostracoda it encloses the whole body and has become truly bivalve, while in the Isopoda and Amphipoda it has disappeared. The post-antennal crustacean limbs have typically a biramous structure owing to the frequent presence of a lateral branch on the second segment from the base of the limb.

These are essentially aquatic animals, but a few members live in damp places on land. Crustaceans encountered in terrestrial habitats are:

Subclass Ostracoda: These have the body enclosed entirely in a bivalve shell which is closed by an adductor muscle. There are no more than two recognizable thoracic limbs. The subclass is predominantly aquatic but New Zealand is rather unusual in that it possesses a terrestrial species, Mesocypris audax (Figs. 10, 10a) which is found in damp moss and litter on the forest floor, usually at fairly high altitudes.

Subclass Copepoda: Crustaceans without compound eyes or carapace. They have typically six pairs of thoracic limbs and none on the abdomen. Here again, this is a predominantly aquatic group, but Harpacticoid members (Fig. 11) often appear in extractions from damp leaf litter. Terrestrial cyclopoids are very rare but nevertheless may be occasionally found.

Subclass Malacostraca: These have compound eyes which are often stalked, and usually a carapace covering the thorax. There is a thorax of eight somites and an abdomen of six or seven, six bearing appendages.

Two suborders within the order Pericarida are represented in the New Zealand bush, both of which are fairly familiar:

Suborder Isopoda ("slaters"): No carapace is present on these animals. The eyes are sessile and the body is depressed dorsoventrally. The thoracic limbs are uniramous, the first - 15 -

pair being modifed as maxillipeds and the rest usually alike (Fig. 12).

Suborder Amphipoda ("hoppers"): The carapace is absent in this group also, and the animals possess sessile eyes. The body is generally compressed laterally. The thoracic limbs are uniramous, the first pair modified as maxillipeds, the remainder, unlike those of the Isopods, of more than one form. The second and third legs are usually prehensile.

All terrestrial Amphipods belong to the family Talitridae.

These latter two suborders are commonly found on the forest floor, amongst litter, under bark and stones.

INSECTA

The Insecta being such a large class, comprising many orders almost all of which are represented in the bush, it would be impractical to list these together with their characters, in this article. Any Entomology text can provide this information. Suffice to say that the class Insecta contributes a countless number of animals, from many orders, to the terrestrial fauna.

CHILOPODA (Centipedes)

These are elongate animals, with the body divided into a variable number of somites, each of which is provided with a pair of limbs used for locomotion. The head bears a pair of multi-segmented antennae and three pairs of mouthparts. Behind the head, the first segment of the body is termed the basilar segment and its appendages are poison claws with which the prey is captured and killed. The number of legs varies from 15 pairs to over 100, but they are always odd in number. The genital opening is situated at the end of the body.

There are several orders of Chilopoda. The Geophilomorpha includes the long, burrowing, worm-like centipedes, with the forepart of each somite marked off from the hinder part by a distinct joint. The legs vary in number from 31 to 177 pairs and the antennae are always composed of 14 segments (Fig. 14).

The Scolopendromorpha differ in never having more than 23 pairs of legs, while the antennal segments vary in number from 17 to 30. Our large Cormocephalus rubriaeps (Fig. 15) is a handsome creature with its dark brown body up to six inches long, and pale blue-green legs. It is usually encountered under stones and leaves and in decaying wood.

The Lithobiomorpha are distinguished from those above by having a body of 15 leg-bearing segments and the antennal segments number 17 - 16 -

to 50. Body segments without spiracles have reduced terga (dorsal plates), producing an uneven segmentation of the body.

Centipedes, in general, inhabit damp, dark, obscure places under stones, fallen leaves, logs, bark and in crevices in the soil. They are primarily carnivorous in feeding habit.

DIPLOPODA (Millipedes)

These are unusual in that most of the body segments are provided with two pairs of limbs. The genital aperture is situated close behind the head. Most have a hard, horny integument. Millipedes are vegetarian and feed on a wide range of plant substances.

Within the order Oniscomorpha are those small millipedes belonging to the family Sphaerotheridae whose body is short, broad, convex above and flat below and which are capable of rolling up into a ball. They have 11 to 13 tergal plates.

Another order represented in New Zealand is the Ascospermophora which have 26 to 32 segments and the tergites are provided with three pairs of symmetrically placed bristles.

The largest millipede order is the Opisthospermophora, the members of which (Fig. 16), have a large and variable number of cylindrical tergal plates. Members of the family Cambalidae are very common in our endemic forests.

SYMPHYLA

The presence of long, many jointed antennae and four pairs of peculiarly modified jaws characterises these animals. There are 12 pairs of walking legs, the basal segments of legs 3 to 12 being provided with a protrusible sac, thought to have a respiratory function. These small, pallid arthropods resemble centipedes in appearance (Fig. 17) and in activity. As in the last two classes, they live in damp places under stones, dead leaves, etc. They appear to be vegetarians with a preference for decaying material. If disturbed, they are generally capable of rapid movement and quickly retreat into the soil.

SOME USEFUL REFERENCES

GENERAL

CLOUDSLEY-THOMPSON, J. L. 1955. Arthropods and Terrestrial Life. Science News, 36: 95-108

______1958. Spiders, Scorpions, Centipedes and Mites. Pergamon Press. - 17 -

PENDERGRAST, J. G. and COWLEY, D. R. 19b5. The Hidden Arthropods of the Bush. N. Z. Sci. Congress Handbook.

STOUT, J. D. 1963, The Terrestrial Plankton. Tuatara, ll(2): 57-65.

ONYCOPHORA

DENDY, A, 189A. Note on a New Variety of Peripatus novaezealandiae (Hutton). Trans. N. Z. Inst., 27: 190-91.

1902. On the Oviparous Species of Onycophora. Q. J. M. S., 45: 368-415.

FLETCHER, J. J. 1900. Note on a N. Z. Peripatus. Proc. Linn.Soc .N . S. W. 75: 116.

WATT, J. C 1960. The N. Z, Onycophora. Tane, 8: 95-103.

WENZEL, R. 1950. Peripatus - Living Fossil and Missing Link. Tuatara, 3(3) '. 98-99,

ARACHNIDA

CAMBRIDGE, O. P. 1873. On the Spiders of N. Z. Trans, N. Z, Inst, 6: 187-207.

CHAMBERLAIN, G. 1946. Revision of the Araneae of N. Z. Rec. Auck. Inst Mus. 3(2): 85-97.

C0MST0CK, J. H. 1912. The Spider Book. Doubleday, Page & Co.

DUMBLETON, L. J. 1962. Acarology in N. Z. N. Z. Ent., 3(1): 3-9.

FORSTER, R. R. 1955. Spiders of the Family Archaeidae from and New Zealand. Trans. ProcRoy. SocN. Z, - 83: 391-403.

______1962-63. A Key to the N. Z. Harvestmen. Tuatara, 10(3):

129-138. Ibid. 11(1): 28-41.

GOYEN, P. 1886. On the N. Z. Araneae. Trans. N. Z. Inst., 24: 253-257.

HUGHES, T. E. 1959. Mites, or the Acari. Univ. of London Press. LAMB, K. P. 1952. A Preliminary List of N. Z. Acarina. Trans. Roy, Soc. N. Z., 79: 370-375.

MYERS, J. G. 1927. Ethological Notes on some N. Z. Spiders. N. Z. Journ. Sci. Tech. 9: 129-136.

RAMSAY, G. W. 1962. N. Z. Oribatei. N. Z. Ent. 3(l): 24-25.

TODD, V. 1945. Systematic and Biological Account of the N. Z. Mygalomorphae. Trans. Roy. Soc. N. Z. 74(4): 375-407. - 18 -

CRUSTACEA

CHAPMAN, M. A. 1961. The Terrestrial Ostracod of N. Z,, Mesocypris audaxt sp. nov, Crustaceane, 2(4): 255-261.

HARDING, J. P. 1958. Bryocamptus stouti and Goniocyclops sylvestris, two new species of Copepod Crustacean from Fores in N. Z. Ann. Mag. Nat. Hist. 13(1). 309-314.

HURLEY, D. E. 1950. N. Z. Terrestrial Isopoda. Tuatara 3(3): 115-127.

______1958. A Key to the Families of N. Z. Amphipods.

Tuatara 7(2): 71-83.

INSECTA

General

IMMS, A. D. 1957. A General Textbook of Entomology. London (9th Ed. )

______1961. Outlines of Entomology. Methuen & Co. Ltd. (5th Ed. )

ROSS, H. H. 1961. A Textbook of Entomology. John Wiley & Son. TILLYARD, R. J. 1926. The Insects of Australia and New Zealand. Sydney. 560pp.

Techniques

PETERSEN, A. 1964. Entomological Techniques. Edwards Brothers Inc.

WOODWARD, T. E. 1951. Collection and Preservation of Insects. Tuatara 4(1): 13-21.

N. B. The following book gives a complete list of the numerous works on N. Z. insects up to the year 1952, so that only major papers or books, published during this period are mentioned below.

MILLER, D. 1956. Bibliography of N. Z. Entomology, 1775-1952. Bull. N. Z. D. S. I. R. 120. 492pp.

Particular Insects

CUMBER, R. A. 1959. Distributional and Biological Notes on Sixteen North Island Species of Formicidae. N. Z. Ent., 2(4): 10-14,

EDWARDS, F. W, 1923. A Preliminary Revision of the Craneflies of New Zealand. Trans. Proc. N. Z. Inst. 54: 265-352.

EVANS, J. W. 1963. Zoogeography of N. Z. Leafhoppers and Froghoppers. Trans. Roy. Soc. N. Z. (Zoology), 3(9): 85-91. 19 -

HARRISON, R. A. 1959. Acalyptrate Diptera of New Zealand. Bull. N. Z. Dept. Scl. Industr. Res. 128: 1-382.

HINCKS, W. D. 1949. Some Earwigs (Dermaptera) from N. Z. Proc. Roy. Ent. Soc. Lond. (B), 18: 201-206.

HUDSON, G. U. 1904. N. Z. Neuroptera. London.

______1928. The Butterflies and Moths of New Zealand. Ferguson and Osborne Pub.

______1934. N. Z. Beetles and their Larvae. Ferguson and Osborne Publcn.

MYERS, J. G. 1926. Biological Notes on N. Z. Heteroptera. Trans. Proc. N. Z. Inst., 56: 449-511.

______1929. The , Phylogeny and Distribution of N. Z. Cicadas. Trans. Ent. Soc. Lond., 77: 29-60.

PARROTT, A. W. 1951. N. Z. Ichneumonidae, Part I. Trans. Roy. Soc. N. Z. 79(2): 286-293.

1952. N. Z. Ichneumonidae, Part II. Ibid. 80(2): 155-170.

1954. N. Z. Ichneumonidae, Part III. Ibid. 81(4): 627-645

SALMON, J. T. 1941. The Collembolan Fauna of N. Z. Trans. Roy. Soc. N. Z. 70: 282-431.

1942. Supplement to Collembola of N. Z., Ibid., 71(4): 254- 259.

______1943. New records of Collembola from N. Z. and a Description

of New Species. Ibid., 73: 1-12.

1950. A Revision of N. Z. Wetas. Rec. Dom. Mus., 1: 124-126.

______1955. Stick Insects. Tuatara 5(3): 77-81.

6: 19-23. 1956. A Key to the Tree and Ground Wetas of N. Z. Tuatara,

Diplopoda

DAWSON, E. W. 1958. Exotic Millipedes (Diplopoda) in N. Z. N. Z. Ent. 2(3): l-5.

HOLLOWAY, B. A. 1956. Revision of the N. Z. Pill Millipedes (Oniscomorpha: Sphaerotheridae). Trans. Roy. Soc. N. Z., 84: 431-446, 20

JOHNS, P. M. 1962. Introduction to the Endemic and Introduced Millipedes of N. Z. N. Z. Ent. 3(1). 38-46.

______1964. The Sphaerotrichopidae (Diplopoda) of N. Z. 1. Introduction, Revision of Some Known Species and Description of New Species. Rec. Cant. Mus. 8(l): l-48.

Chilopoda

ARCHEY, G. E. 1916. The Lithobiomorpha of N. Z. Trans. N. Z. Inst, 49: 303-318.

______1917. The occurrence in N. Z. of Crasterostigmus ta&manianuB Pocock (Chilopoda) Trans. N. Z. Inst., 49: 319-320.

______1921. Notes on N. Z. Chilopoda. Trans. N. Z. Inst., 53: 181-195.

REQUEST FOR RESEARCH MATERIAL

Miss M. H. Barclay of the Zoology Department requires Harpacticoid and Cyclopoid copepods with the aim of producing a list of all N. Z. freshwater species.

Cyclopid copepods are fairly common in most standing bodies of water, both in the littoral and open waters. Their small size necessitates the use of a net of fine mesh for their capture. Harpacticoids are not as common and their minute, worm-like forms are more generally encountered crawling over the bottom mud than swimming freely in the water.

Specimens of these animals collected from anywhere in N. Z. would be gratefully accepted. They should be preserved in 60% alcohol and forwarded, together with a note as to locality and date collected.