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Volume 47, 1914
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Art. XXXII.—The Fresh-water Crayfish of New Zealand.

[Read before the Canterbury Philosophical Institute, 2nd December, 1914.]

Plate IV.

In the following pages an account is given of the species and varieties of the New Zealand fresh-water crayfish, and of their distribution. This subject had previously been worked at, but had not been definitely settled, some doubt existing as to whether the crayfish found in Canterbury and Otago were to be considered as distinct species or only as varieties.

This paper contains, first, a summary of the work hitherto published on the subject; this is followed by a description of the crayfish found in the different parts of New Zealand, and an account of the distribution of the species and varieties. Some notes on the habits and mode of life of the crayfish are then given, diagnoses of the species, and a bibliography.

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Both in collecting material and in the arrangement of this paper I was given much valuable assistance by Dr. Chilton, to whom I wish now to tender my sincere thanks. I have also to thank Dr. Benham, who offered many helpful suggestions.

Historical.

The genus Paranephrops was created in 1842 by Adam White, who described as the type species Paranephrops planifrons. “Dieffenbach's Travels,” published during the following year, also contained a description of P. planifrons White, in which reference was made to supposed resemblances to Nephrops. White again, in 1847, described a specimen, collected by Mr. Percy Earl, under the name Astacus zealandicus. In this paper he made no reference to Paranephrops planifrons, which he had described five years previously. The species described as A. zealandicus is clearly that now known as Paranephrops zealandicus. This description of White's was republished in the following year in the “Annals and Magazine of Natural History.”

In 1852 J. D. Dana described a crayfish obtained from the Bay of Islands, under the name Paranephrops tenuicornis. It had, on the squame of the antenna, an inner apex not far from the end, “mostly concealed by the fringe of plumose setae, which extends along the inner margin.” This feature is figured in his Atlas; it will be referred to later in this paper. In his “Classification of the Crustacea” (1859) Dana includes Paranephrops under the Nephropinae, family Astacidae.

In 1873 Captain F. W. Hutton described a new species of Paranephrops which he named P. setosus. This species had a thorny-sided carapace, a slight median ridge on its upper surface, the hand bearing spines and numerous long hairs on its outer surface, and a broad flattened rostrum. The habitat given was “stream near Invercargill, Province of Otago; and River Avon, near Christchurch, Canterbury.” The specimen from Invercargill would probably belong to the species now known as P. zealandicus.

Miers (1874), in the list of Crustacea of the “Erebus” and “Terror” expedition, mentions P. planifrons and P. zealandicus. He thought that P. tenuicornis Dana and P. planifrons White were identical, and that the form described by White (1847) under the name of Astacus zealandicus should be referred to Paranephrops.

J. Wood-Mason (1875), in a note on Temnocephala, an external parasite found on these fresh-water crayfish, remarked that he had received from Captain Hutton a series of specimens of the fresh-water crayfish lately described by him in the “Annals and Magazine of Natural History” under the name of Paranephrops setosus. He continues, “I have since received from my friend Mr. W. Guise Brittan, of Christchurch, an abundant supply of each of two species of crayfish from the Rivers Avon and Waimakariri respectively.” The italics here are mine; the question as to there being distinct species in the Rivers Avon and Waimakariri will be discussed later. In 1876 Wood-Mason exhibited before the Royal Society of Bengal some specimens of New Zealand crayfish to which he gave the name Astacoides tridentatus, “from the presence of three spines on the inferior edge of the rostrum.” These specimens are now in the Indian Museum.

In the same year he published a note on the “Mode of Attachment of the Young of Astacoides zealandicus,” which species, he said, was the same as Paranephrops setosus Hutton; but Miers (1876) considered it to he P. zealandicus.

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In 1876 E. J. Miers published a “Catalogue of the Crustacea of New Zealand,” in which he recognizes the three species—P. planifrons, P. zealandicus, and P. setosus—quoting White's original description for P. planifrons (1842) and for P. zealandicus (1847), and that of Hutton for P. setosus (1873).

Dr. Chilton, in his first paper on the fresh-water crayfish (1883), definitely described the differences between the English crayfish (Astacus fluviatilis) and a New Zealand one (Paranephrops setosus). P. planifrons he recognized as a species quite distinct from the South Island form; but he agreed with Professor Hutton that P. zealandicus, which was described by White in 1847, and had not since then been recognized in New Zealand, was probably “nothing more than a young specimen of P. setosus Hutton.”

In 1885 Filhol recorded the three species, P. planifrons White, P. zealandicus (White), and P. setosus Hutton.

In 1889 Dr. Chilton published a second paper on the subject, entitled “The Distribution and Varieties of the Fresh-water Crayfish of New Zealand.” The investigation was undertaken with a view to settling the question raised in his first paper (1883) of the identity of the two species P. setosus Hutton and P. zealandicus (White). He remarked that the characters in which they differ varied to a large extent, owing to size and age, even in specimens taken from the same stream, and such a complete series of transitions was found that it would, he thought, be found necessary to combine the two species. The name then given to the South Island species was P. neo-zelanicus. P. planifrons, too, exhibited a wide range of variable characters, sometimes approaching the South Island form. An important point was the distribution of P. planifrons, commonly called the North Island species, but found also all over the north-western part of the South Island. Dr. Chilton's conclusion was: “It would hence appear that Cook Strait has not proved so great, or, rather, so old a barrier to these crayfish as the mountains in Nelson forming the northern continuation of the Southern Alps.”

Walter Faxon (1898) gave a detailed description of the three species from material supplied by Dr. Chilton. He considered P. tenuicornis Dana to be the same as P. planifrons White. With regard to P. zealandicus (White) and P. setosus Hutton, which Dr. Chilton (1889) had combined under the name P. neo-zelanicus, he considered that “the two species are perfectly distinct, even young, very small specimens being easily distinguishable.”

Dr. H. Lenz (1901) recorded the occurrence of “P. setosus” from D'Urville Island, but as the specimens I have received from this locality and from Nelson and Blenheim are all distinctly P. planifrons I have concluded that his identification is incorrect. There is nothing in the description given to indicate definitely to which species it belongs.

It will be seen from the foregoing that there has been some difference of opinion as to whether P. zealandious and P. setosus are to be regarded as distinct species or not. In the latter part of the following description of the species this subject will be discussed.

General Account of the Species of Paranephrops and their Distribution.

The method adopted of working out the variations with a view to determining the distribution of the different species or varieties was that of comparative measurement for proportion. A series of measurements

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was made, and certain proportions calculated for each specimen; and, in addition, the details of the spinulation or of the shape of different parts were recorded. From the tables thus compiled could be obtained more definite evidence of the existence of different local varieties than by mere observation.

In arranging the spines on the carapace into groups I have followed the system given by Dr. Chilton (1889, p. 243), and the “group letters” used here refer to the same sets of spines as they do in Dr. Chilton's paper. I have added group K, consisting of 3 or 4 small spines situated above the branchio-cardiac groove, and group L, found only in P. setosus and P. zealandicus, placed on the posterior portion of the gastric area, level with group B.

A. General Description of Paranephrops Planifrons. (See Plate IV, fig. 1, and text fig. 1; also measurements, Table 1, p. 313.)

I. Carapace, Length ÷ Breadth (column 2).

There is a slight indication here that the crayfish grow a little stouter, comparatively, as they increase in size; but the difference is very much less than in P. setosus. There are no local variations with regard to this proportion.

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Fig. 1.—P. planifrons White. Specimen from Ross, Westland.
II. Bulging of the Sides of the Cacapace.

The sides of the carapace are, in moderate-sized individuals, practically straight, or, at most, with only a slight bulge; in the larger specimens, however, from Wanganui, New Plymouth, and Napier, there is a distinctly oval carapace, further emphasizing the fact that the animals grow comparatively stouter as they increase in length.

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III. Nature and Arrangement of the Spines on the Carapace (fig. 2).

A. Two sharp spines always present.

B. Average number 5, present in specimens 60 mm. or more in length.

c. Increase in number according to the size of the specimen, up to 5 or 6.

D. Vary in number with the size of the specimen; they are sometimes situated on a slight ridge on the carapace.

E. One or 2 (very rarely 3), on a distinct ridge.

F. Present only in large crayfish; usually 3 in number.

G. These spines vary in number from 0 to 6, in accordance with the size of the specimens. Specimens about 80 mm. long have either 3 or 4.

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Fig. 2.—Carapace of P. planifrons, showing arrangement of spines.

H. This group varies in number from 4 to 13, independently of size, sex, or locality; 7 and 9 are most commonly found.

J. The anterior portion of this region is armed with spines, merging into small rounded tubercles posteriorly.

K. Present in the larger specimens only; usually 3 or 4 in number, but 11 have been found here.

IV. Total Body Length ÷ Rostrum Length (column 4).

The usual specific proportion is 6·5. The Hawke's Bay and Napier specimens have a slightly longer rostium (average proportion, 5·96), and the Wellington and north-east Marlborough specimens have a very short rostrum (proportion, 7·1)—shorter, indeed, than in P. setosus.

V. Rostrum Length ÷ Rostrum Breadth (column 3).

There is not much definite variation correlated with definite localities, but the rostrum of crayfish from south of Wellington (inclusive) is considerably wider than that of those in the north. There are individual exceptions to this rule—e.g., D'Urville Island and Spring Creek specimens have a narrow rostrum, while the Rotorua specimens have a wide one; but generally the proportion is the same.

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VI. Carina on Rostrum.

There is a median keel extending forward from the cervical groove as far as the anterior of the post-orbital spines (group A) in all specimens of P. planifrons. This keel is continued anteriorly to about half-way along the rostrum in specimens from Richmond, Murchison, and Pelorus.

VII. Spines on Rostrum (column 5).

The most usual number of spines on the rostrum is 4 on each side, with 1 or 2 below (occasionally 0 or 4). Specimens from the Eastern Cook Strait district have often 5 spines on each side, and this shows an approach to P. zealandicus. The northern specimens (Puriri and Manukau) have only 3 on each side.

VIII. Rostrum Length in Proportion to the Length of the Peduncle of the Antenna.

The rostrum terminates level with or slightly beyond the peduncle of the antenna in all but the Western South Island group, where it reaches only to half-way along the last segment of the peduncle.

IX. Antennal Scale.

(a.) Length in Proportion to the Total Body Length (column 6).—The length of the antennal scale varies in accordance with the locality. It is shortest in the Eastern Cook Strait group (8·4 average proportion), longer in the Western South Island group (7·8), considerably longer in the ordinary North Island group (6·6), and exceptionally long in the Manukau specimens. The proportionate length of the squame in the Eastern Cook Strait group is less than in P. setosus.

(b.) Squame ÷ Peduncle (column 7).—The figures here show that the squame is shorter than the peduncle in the Western South Island and the Eastern Cook Strait groups, while in the ordinary North Island forms the squame is slightly longer.

(c.) Shape (fig. 3).—The squame is normally long and narrow, tapering from the posterior third. The variations found are that the Ross specimens were slightly broader (they were very large crayfish); those from Murchison were very distinctly short and broad, two small specimens having an almost semicircular squame. With the exception of the Spring Creek forms, the Eastern Cook Strait group showed a slightly broader squame, in which the broad appearance was somewhat accentuated by the tapering not commencing till nearly half-way along its length. The Manukau and Puriri crayfish had exceptionally long, antennal scales.

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Fig. 3.—Antennal scale of P. planifrons; X 3.

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Fig. 4.—Antennal scale of P. tenuicornis Dana (after Dana).

The opportunity is taken here to refer to Dana's (1855) drawing and description of the squame of P. tenuicornis of P. planifrons), said to have

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a tooth placed anteriorly on the inner edge. In all the crayfish I have examined I have never seen this tooth as pictured by Dana. There is, however, in some of the specimens a rather sharp turn in the sweep of the edge of the squame, which, if exaggerated, might suggest a spine or tooth. The specimen examined by Dana was obtained from Bay of Islands. I have not seen any crayfish from this locality (the most northern forms I have examined are from Manukau Harbour), and therefore cannot say whether a variety with this character actually exists, or whether the artist has exaggerated the “corner” on the inner edge of the squame.

X. Length of Carapace in Proportion to the Length of the Body.

The measurement was taken from the tip of the rostrum to the middle of the posterior edge of the carapace. The only indication of locality groups with regard to this character is that the Rotoiti and Thames specimens have a somewhat shorter carapace; but in each locality where male and female specimens were obtained the female has a shorter carapace than the male.

XI. Chelae; Propod Length ÷ Propod Breadth.

The average proportion for ♀ is 3·36, that for ♂ is 3·16, indicating that the, propod of the female is slightly broader than that of the male.

XII. Spinulation of the Chelae (fig. 5, a and b).

There is usually a single spine on the lower surface of the basis, though there may be 2 or 3 in large individuals. In small specimens the upper surface of the ischium is smooth, but in moderate-sized individuals it becomes toothed with from 3 to 5 edentations. From its lower surface 2 sharp spines project, with from 1 to 6 smaller spines or tubercles lying between them.

On the upper edge of the merus, there are 2 rows of irregularly placed spines, the outer row consisting of 2 or 3 small tubercles posteriorly, and 3 or 4 spines anteriorly. The lower surface has 2 rows of either 5, 6, or 7 spines. A sharp spine is present on each side of the anterior end of this joint, and sometimes there is a complete ring of about 7 spines here. This ring is particularly noticeable in Napier, Hawke's. Bay Wanganui, and New Plymouth specimens. and in some Boss and Nelson specimens.

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Fig. 5.—Chela of P. planifrons: a, from above; b, from below.

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The inner margin of the carpus has 3 or 4 large sharp spines; its upper surface is provided with 2 irregular rows of blunt spines; on some small specimens 5 or 6 blunt spines are found on the outer surface of the carpus; in larger specimens these spines are sharp; there are usually 4 spines on the lower surface.

The inner margin of the propod is armed with 2 rows of large sharp spines, which are continued on to the corresponding margin of the dactyl. The upper surface of the propod has 2 median parallel rows of spines, and smaller irregularly arranged tubercles on the outer region; the outer margin has 2 parallel rows of short close-set spines. The spinulation of the lower surface is very similar to that of the upper surface, except that there is a tendency for the outer small tubercles to run in either 2 or 3 irregular rows.

There is always a large spine situated centrally on the posterior margin of the dactyl, and also one in a corresponding position on the lower surface.

Both the carapace and chelae are singularly free from hairs; when present, they occur on the anterior side of the base of the tubercles, and are not observed at a casual glance.

Distribution of P. Planifrons.

P. planifrons can be divided into four rather ill-distinguished groups, the tendency throughout being towards more slender crayfish as we go farther north.

The first group, which may be regarded as the normal, extends over the central part of the North Island—the district bounded by Masterton, Wanganui, New Plymouth, Whangarata, Rotorua, and Napier. The foregoing description will, in general, apply to this group.

The second, or Northern group, found north of Whangarata, is characterized by a greater slenderness of form, both in the body and in the chelae.

The East Cook Strait group, which includes specimens from Wellington (city), Marlborough, and Pelorus Valley, is marked by an approach in the proportion of certain parts to P. setosus—that is, the crayfish have a short, broad rostrum with 5 spines on either side, and a shorter and broader squame. It is to be noted, however, that the Spring Creek and D'Urville Island specimens have the characteristic long narrow squame and rostrum of the normal North Island form.

The last group, the Western South Island group, differs only slightly from the normal group, having a slightly shorter squame, tapering from half-way, and a shorter, though not comparatively broader, rostrum. In some specimens of this group there is a median rostral carina.*

Although the last two groups show an approach in certain proportions to P. setosus, there is no doubt whatever that they are P. planifrons, the arrangement of the spines on the carapace and chelae, and the shape of the carapace and chelae, being distinctly that typical of P. planifrons.

[Footnote] * When this was written. I had examined specimens of P. planifrons only from as far south as Ross, but had heard that crayfish, presumably P. planifrons, were to be found in the Wanganui River, about twenty-five miles farther south. Recently, however, I received a specimen, unmistakably P. planifrons, from Cromarty, near Preservation Inlet. So we now have P. planifrons extending all along the west coast of the South Island, evidently separated from P. zealandicus by the main watershed of the Island. At Clifden, to the east, distant fifty miles direct from Cromarty, the crayfish are the most perfectly definite forms of P. zealandicus.

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The following table shows the average proportions of the parts measured in each of the above groups. Only those proportions which show differences between the groups are given.

[The section below cannot be correctly rendered as it contains complex formatting. See the image of the page for a more accurate rendering.]

Body Length ÷ Squame Length. Body Length ÷ Rostrum Length. Rostrum Length ÷ Rostrum Breadth. Rostrum Spines.
Normal group 6.6 6.23 2.30 4-4/1.5
Northern group 6.0 5.60 2.40 3-3/1
East Cook Strait group 8.4 6.50 1.82 5-5/1
West South Island group 7.8 7.10 2.08 4-4/1

B. General Description of Paranephrops Setosus. (See Plate IV. fig. 2, and text fig. 6; also measurements, Table 2, p. 314.

Paranephrops setosus is found in the rivers of Canterbury as far south as Winchester. Specimens were examined from Omihi, Rangiora, Wairaakariri River, Styx River, Avon River, Heathcote River, Leeston, Peel Forest, and Winchester.

I. Carapace.

P. setosus is distinguished by a distinctly oval carapace, narrowing towards the anterior end. Specimens from Winchester and Peel Forest, however, have a less oval carapace. By comparing column 1 with column 2 in Table 2 it will be seen that the animals become comparatively stouter as they increase in length.

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Fig. 6.—P. setosus. Specimen from River Avon.

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II. Nature of the Spines of the Carapace.

The carapace of P. setosus is covered with, sharp, forwardly directed spines, which can be arranged in the same reference groups as in P. planifrons. The arrangement of the spines is exactly, the same in P. zealandicus as in P. setosus, but in P. zealandicus rounded tubercles take the place of the sharp spines. The following account of the arrangement of the spines will be equally applicable to the two species.

III. Arrangement of the Spines on the Carapace, P. setosus and P. zealandicus.

A. Constantly 2 in number.

B. Increasing in number according to the size of the specimen. In moderate-sized individuals the number is from 6 to 8.

C. Usually 4 or 5, appearing first in specimens of 50 mm. length.

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Fig. 7.—Carapace of P. setosus, showing arrangement of spines.

D. There are generally from 10 to 12 spines here; they are first developed in specimens 50 mm. long.

E. A ridge on the carapace in this region bears 1 or 2 spines; occasionally a third is developed.

E. Five or 6 is the greatest number found here; they appear only in the large specimens.

G. This group is constant in specimens of 50 mm. or more in length. The spines, which are very distinct, are usually 3 or 4 in number.

H. Five or 6 spines appear here in specimens 40 mm. long; the usual number in ordinary-sized individuals is 8.

J. These are quite distinct and fairly numerous just behind the cervical groove, but become fewer and less distinct posteriorly.

K. These spines are not often present, and do not appear in specimens under 90 mm. long. When present, there are only 4 or 5 developed.

L. This is a large group, varying considerably in number. The usual number for moderate-sized specimens is 10–12.

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IV. Rostrum (columns 3, 4, and 5).

The rostrum is shorter in proportion to the body length than in P. planifrons, and it is also shorter in proportion to its own width. Specimens from Rangiora and Peel Forest have a rostrum still shorter than is usual for the species. There is also a distinct median keel on the anterior portion of the upper surface of the rostrum; it is not so distinct in the Peel Forest specimens. There are usually 4 sharp distinct spines on each side of the rostrum, and 1 or 2 below.

V. Antennal Scale (columns 6 and 7; fig. 8).

The antennal scale is fairly long and narrow, though not so long as in P. planifrons; it is nearly as long as the peduncle of the antenna; it tapers from the posterior third.

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Fig. 8.—Antennal scale of P. setosus; X3.

VI. Chelae (fig. 9).

The upper surface of the ischium is slightly serrated in moderate-sized individuals, but large specimens have distinct, forwardly directed teeth; on the lower surface are 2 sharp spines, with 1 or 2 small tubercles between them in large specimens.

On the posterior portion of the upper margin of the merus is a single row of spines leading forward on the anterior part to 2 rows; there are 2 irregular rows on the lower margin, and on each side of the anterior margin is a single forwardly directed spine.

The inner surface of the carpus has usually 3 large spines; the upper surface has 2 irregular rows of small spines, separated by a shallow groove; there are small tubercles on the outer surface, and 3 or 4 large sharp spines on the lower surface.

On the inner margin of the propod there is a row of sharp spines, continued, with smaller spines, along the corresponding edge of the dactyl. Above this row there is, on the dactyl, another row of smaller spines, commencing usually with 1 spine on the anterior portion of the propod. The outer edge of the propod has 2 rows of close-set, short spines. On the posterior

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part of the upper surface there are long spines arranged irregularly; these merge anteriorly into 2 rows. Two median rows are present on the lower surface of the propod.

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Fig. 9.—Chela of P. setosus: a, from above; b, from below.

There are abundant tufts of hair on the propod, but they do not hide the spines.

C. General Description of Paranephrops Zealandicus. (See Plate IV, fig. 3, and text fig. 10; also measurements, Table 3, p. 314.)

Specimens of P. zealandicus were obtained from Tinwald, Waimate, Glenavy, Gamaru, Waitati, Dunedin, Wyndham, Clifden, and Stewart Island.

The carapace is nearly cylindrical in shape, and does not bulge, as in P. setosus. This does not mean that P. zealandicus is more slender than

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P. setosus, for the shape of the latter is due to the narrowing of the anterior part of the carapace. In fact, the measurements indicate that P. zealandicus has a very slightly wider carapace than P. setosus. As mentioned above, rounded tubercles replace the spines on the sides of the carapace of P. setosus.

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Fig. 10.—Pa. zealandicus (White). Specimen from Waimate.

The rostrum (columns 3, 4, and 5) is considerably shorter and broader in P. zealandicus than in P. setosus; there is no median keel on its anterior portion; and there are 5 blunt tubercles on either side, and none or 1 on the under-surface.

The antennal scale (columns 6 and 7; fig. 11) also is shorter and broader in P. zealandicus than, in P. setosus; the broad appearance is enhanced by the fact that it tapers abruptly from half-way.

Chelae.—The spinulation of the chelae differs in certain points from that in P. setosus. On the upper surface of the carpus small rounded tubercles are found instead of spines; the upper surface of the propod is provided with a few tubercles, completely bidden by dense tufts of hair; these tubercles are arranged irregularly posteriorly, merging to one median row anteriorly. In other respects the arrangement of the tubercles is similar to that of the spines on the chelae of P. setosus (cf. fig. 9).

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Fig. 11—Antennal scale of P. zealandicus; x 3.

Distribution of P. setosus and P. zealandicus.

P. setosus is found only on the eastern side of the South Island, from Omihi in the north, to Winchester in the south. I have not obtained them from among the mountains, but only from the lower parts near the coast, and then not from the rapid shingle-bed rivers themselves, but from creeks or pools leading into them. The results of observations by tourist parties and the mountain guides, to whom application was made, as to their occurrence high above the sea-level or in the cold rapid mountain torrents are entirely negative. It is to be noted that, although the Winchester specimens

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are distinctly P. setosus, north of this—at Peel Forest and Tinwald—are found crayfish which it is difficult to place definitely in either species. They have some of the characters of P. setosus and some of P. zealandicus. They have been assigned to the species of which, they have the most characters. The Peel Forest specimens are, therefore, named P. setosus, and the Tinwald specimens P. zealandicus. South of Winchester the crayfish found are all distinctly P. zealandicus, which extends right to the south of the Island and to Stewart Island, and has been traced in the south-west as far as Clifden. Here, also, there is no definite record of their occurring far up the rivers, although a gentleman writing from Gore, in Central Otago, states that they used to be common in the district, and a correspondent from Lawrence reports that they are found there.

In the historical portion of this paper mention was made of the occurrence recorded by J. Wood-Mason (1875) of “two species of crayfish from the rivers Avon and Waimakariri respectively.” Through the kindness of Mr. S. Kemp, of the Indian Museum, Calcutta, the specimens which formed the subject of Wood-Mason's paper were obtained for examination. They were entered in the Indian Museum Register as follows:—

“900. Astacoides setosus, Hutton. R. Waimakariri, N.Z., a few miles within influence of tide. W. Guyse Brittan.”

“901. Astacoides tridentatus, Wood-Mason. Types. R. Avon, N.Z. Several miles above tidal influence. W. Guyse Brittan.”

Of these, No. 901 belong to Paranephrops setosus Hutton, of which Astacoides tridentatus Wood-Mason is a synonym, and no doubt really came from the River Avon. But No. 900 really belong to P. zealandicus White, and probably came not from the River Waimakariri, but from the Bluff, the locality label having been interchanged with other specimens, “No. 890/7,” which are labelled as coming from “The Bluff, S. Is. N. Zealand, A. V. Hugel”; these, however, are undoubtedly specimens of P. setosus Hutton, and doubtless came from the Waimakariri.

Bionomics.
(A.) Mode of Life.

It has been seen that crayfish are to be found in most parts of New Zealand, but their number and size vary in the different districts, seemingly in accordance with the type of stream or pool in which they are found. Soft, muddy river-beds seem to be their favourite homes, while they are often found in-holes in a sunken log or burrowing among the roots of trees growing on the river-banks. An example of their restriction to this type of locality is seen in their occurrence in the Waimakariri River. This stream divides into two branches about twenty miles above its mouth; of these, the south branch is the typical rapid shingle-bed river, while the north branch flows comparatively slowly between soft banks. Crayfish have been obtained from the north branch, but I have never heard of their having been found in the south branch.

Two other localities where they are said to occur in great numbers, and to grow to a large size, are the plains of Southland and the holes and pools in the basins lying among the hills of South Canterbury. They are also plentiful, in the streams draining the low-lying somewhat swampy, land around Christchurch. In parts of Southland the water-races are said to be “simply swarming with crayfish,” which sometimes do an immense amount of damage by burrowing into the banks.

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Since this paper was read before the' Canterbury Philosophical Institute Mr. A. Dudley Dobson has informed me that some years ago, when water-races were first constructed from the Murray River in Australia, the crayfish did so much damage to them that the races had to be lined with concrete.

Amongst the hills around Waimate are many deep pools, known as the “Crayfish Holes,” from which the crayfish can be taken in any quantity. Faxon (1898, p. 681), quoting from a letter received from Dr. Chilton with regard to specimens obtained near Dunedin, observed that the specimens taken from small streams were of very small size, though sexually mature, and had few spines, while those taken from a reservoir formed by damming up one of the small streams attained a length of 158 mm. and were heavily tuberculated. This is also the case with the specimens I have used, and it seems that fairly deep, slow-moving waters provide the best conditions for their growth.

A similar example of the connection between the size of an animal and the volume of water in which it lives appears in Semper's volume on “Animal Life” (1899, pp. 160–61) in the International Scientific Series, which contains an account of two series of experiments connected with the growth of a gastropod mollusc—Limnaea stagnalis—-living in different volumes of water, but otherwise in equally favourable conditions for growth. The results were that “the smaller the volume of water which fell to the share of each animal, the shorter its shell remained.”

The abundance of crayfish in special localities suggests that it would be possible to breed the animals for use as articles of food, for they are said to be excellent eating; but it would be necessary, before this could be done successfully, to ascertain the number of years they require to grow to a full size, as well as to obtain more definite information with regard to their breeding and life-history. The frequent floods to which so many of our rivers are subject are the cause of the destruction of large numbers of crayfish, which may be washed out of the small streams into the deep rapid rivers. A correspondent from Southland has stated that he has seen hundreds washed up on the lower beaches of the large rivers after a flood. It is also evident that, in common with other members of our native fresh-water fauna, the crayfish are being destroyed by eels and the introduced fishes. Trout have been caught with partly digested crayfish in their stomachs, and it is probable that the restriction of crayfish to such places as cannot be inhabited by these fish is only a matter of time.

(B.) Food.

Some specimens were-kept for a time in large glass battery-jars, into which was thrown a certain amount of river-weed, mainly for the aeration of the water. The crayfish were never actually seen eating any of this, but at evening it was noted that the bottom, of the jar was quite clean, while in the morning there would be seen lying around chopped-up pieces of the plant. Small worms or pieces of meat placed in the jar were invariably left untouched, though crayfish are often caught by using meat as bait. An examination of the contents of the stomach of several individuals showed the presence of the roots and stems of plants, pieces of such fresh-water algae as Spirogyra and Vaucheria, together with broken fragments of the different kinds of small animals generally found amongst the river-weed. A fairly large piece of the flesh of some animal was found in the stomach of one individual.

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(C.) Colour.

The colour is usually a mottling of green and grey, which harmonizes well with the beds of streams; some, however, are of a yellowish or a light-brown colour. Those taken from the ponds of the New Plymouth Public Gardens are almost black in colour, and this is no doubt correlated with the colour of the mud on the bottom of the ponds, which Mr. W. W. Smith, the curator, tells me is quite black. Some specimens from the Wanganui River were also very dark.

It is an interesting fact that now and then a crayfish is met with that is of a bright-red colour, similar to that of a boiled lobster.

Dr. Marion Newbigin (1898, pp. 117, 129), in her book “Colour in Nature,” divides the colours of Crustacea into two series, the first series containing the red lipochromes and a yellow pigment, while the second series contains soluble blue pigments. She further shows that there is reason to believe that “when mixed with the yellow pigment, or with the red lipochrome, this blue pigment gives rise respectively to green and brown colours” (p. 129).

A possible explanation, then, of the occurrence of red crayfish might be that the pigment representing the soluble blue series is absent in these forms. That the blue pigment is the less stable is seen in its disappearance when crayfish are boiled or placed in alcohol. In connection with this, Dr. Newbigin states that in the living animal “the blue or cyanic series occur … in solution, while the reds occur in fixed anatomical elements—the chromatophores.”

(D.) Eggs.

The fresh-water crayfish become sexually mature a considerable time before they attain to their full size. Several ovigerous females were obtained which were only 52.5 mm. in length; but these were from the Khandallah Stream, Wellington, from which no specimens greater than 77 mm. were taken. Many of the ovigerous females, however, taken from other districts were not equal in size to the largest specimens from their district. As is to be expected, the number of eggs carried increases in proportion to the size of the crayfish. The accompanying table shows the number of eggs carried on some different-sized females:—

Length of Animal. Mm. Number of Eggs.
52.5 23
57.0 26
66.0 56
71.0 60
76.0 72
90.0 120
96.0 160

(E.) Difference noted between Males, Ordinary Females, and Ovigerous Females.

With regard to the relative width of the abdomen in males and females, I found that when trying to pick out the males from the females by looking at them from above I was as often wrong as right. Ovigerous females, however, could usually be detected. Below are given the average proportion

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(“total length ÷ breadth of abdomen”) for five ovigerous females, six females without eggs, and ten males all collected around Wellington:—

Males 4.95
Females without eggs 5.03
Ovigerous females 4.58

It can be seen, then, that the females usually have an abdomen no broader than that of the males, but that when they are bearing eggs their abdomen is slightly broader. This is due not to any actual increase in size of the abdomen, but to its being slightly flattened, the pleura projecting outwards to a slight extent.

(F.) Relative Abundance of Males and Females.

The males and females seem to be present in fairly equal numbers. Of those I have examined, fifty-eight are males and forty-three females; but large collections from the different localities will be necessary before any significance can be attached to these numbers. In comparing the relative sizes of the males and females it was noticed that in specimens from the different localities the male was more frequently the larger. It is to be noted, farther, that the largest specimens obtained were three males from Dunedin. Further information, however, is required on this point also.

Diagnoses of the Species of Paranephrops.
Genus Paranephrops White.

Paranephrops White, Gray's Zoolog. Miscell., No. 2, p. 79, 1842. Type: Paranephrops planifrons White.

Paranephrops planifrons White.

Paranephrops planifrons White, Gray's Zoolog. Miscell., No. 2, p. 79, 1842. P. tenuicornis Dana, Crust., Classif. and Geograp. Distrib., p. 1433, 1853. P. planifrons Filhol, Institut de France, iii, 2nd part, No. 1, p. 429, 1885; Chilton, Trans. N.Z. Inst., vol. 21, pp. 242–49, pl. x, figs. 1–3, 1889; Faxon, Proc. U.S. Nat. Mus., vol. 20, p. 678, 1898 (with references); Chilton, Trans. N.Z. Inst., vol. 32, p. 14, 1900. P. setosus Lenz, Zool. Jahrb., vol. 14, p. 441, 1901.

Carapace nearly cylindrical, of the same width throughout whole length of the branchiostegites, smooth, or with small tubercles or spines on the sides. Rostrum elongate, triangular, somewhat depressed, margins raised and usually with 4 teeth on each side, under-surface keeled and usually with 2 teeth. Basal scale of antenna long and narrow, tapering from posterior third, with further abrupt narrowing near the end, Teaching as far as or beyond extremities of rostrum and penduncle of antenna. Median keel on the carapace extending from the cervical groove to the level of the anterior of the post-orbital spines. Chelae long and narrow, propod more than three times as long as broad, whole appendage densely spined, with spines arranged in rows on the propod, inner margin of propod armed with 2 rows of spines, hairs few or absent. Pleura of abdominal segments rather pointed at the infero-posterior angle, anterior edge longer and more convex than the posterior, and fringed with setae, posterior edge sinuous and scarcely curving forward.

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Size.—From 49 mm. to 125mm.

Hab.—Streams in North Island, and northern and western part of South Island, D'Urville, and Kapiti Islands.

Paranephrops zealandicus (White).

Astacus zealandicus White, Proc. Zool. Soc., London, pt. 15, p. 123, 1847. Paranephrops zealandicus Filhol, Institut de France, iii, 2nd part. No. 1, p. 429, 1885. P. neo-zelanicus Chilton (in part), Trans. N.Z. Inst., vol. 21, p. 249, 1889. P. zealandicus Faxon, Proc. U.S. Nat. Mus., vol. 20, p. 680, 1898 (with references); Chilton, Trans. N.Z. Inst., vol. 32, p. 15, 1900.

Cephalothorax cylindrical; carapace nearly smooth in small specimens, but in larger forms with rounded tubercles on the branchiostegite, along the cervical groove, and on the gastric area; a median carina runs over the gastric area, ceasing abreast of the anterior of the post-orbital spines; rostrum one-eighth as long as the body, and more than half as broad as long, slightly depressed, the edge thickened, with usually 5 small denticulations on each side; under-surface either unarmed or with 2 small spines. No median keel on the upper surface of the rostrum. Basal scale of antenna short and broad, tapering from half-way and projecting not quite as far as the peduncle. Chelae shorter and broader than in P. planifrons; propod two and a half times as long as broad, hand provided with spines on outer and inner margins, with rounded tubercles on the upper and lower surfaces, hidden by dense tufts of fine silky hair, arranged in longitudinal rows; inner margin of propod has only one row of spines.

Size.—54mm. to 130 mm.

Hab.—Streams in South Canterbury, Otago, and Stewart Island.

Paranephrops setosus Hutton.

Paranephrops setosus Hutton, Ann. Mag. Nat. Hist., 4th ser., xii, p. 402; 1873. Astacoides tridentatus Wood-Mason, Proc. Asiatic Soc. Bengal, 1876, p. 4. A. zealandicus Wood-Mason, Ann. Mag. Nat. Hist., 4th ser., xviii, p. 306, 1876; Filhol, Institut de France, iii, 2nd part, No. 1, p. 429, 1885. Paranephrops neo-zelanicus Chilton (in part), Trans. N.Z. Inst., vol. 21, pp. 246–49, pl. x, figs, la, 2a, 1889. P. setosus Faxon, Proc. U.S. Nat. Mus., vol. 20, p. 681, 1898 (with references); Chilton, Trans. N.Z. Inst., vol. 32, p. 16, 1900.

Carapace oval, bulging behind the cervical groove, armed with distinct, forwardly directed, sharp spines along the cervical groove, and on the branchiostegite and gastric area. A median carina runs over the gastric area, and is continued less distinctly over the rostrum. Rostrum one-sixth of the total length of the body and twice as long as broad, depressed, edges raised and armed with, usually 4 sharp, forwardly directed spines on each side, lower surface with a downwardly projecting median keel, armed with 1 or 2 spines. Basal scale of antenna longer than in P. zealandicus, tapering from the posterior third, projecting as far as or beyond peduncle. Chelae of the same proportions as in P. zealandicus, but with hairs less dense, and armed with prominent spines projecting above the hairs, but otherwise with the same arrangement as P. zealandicus.

Size.—35 mm. to 103 mm.

Hab.—Streams in North and Central Canterbury.

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Table 1.—Average Measurements of Specimens of Paranephrops planifrons from each Locality.
Column No. 1. 2. 3. 4. 5. Antennal Scale.
Specimen. Average Length. Carapace Lenght ÷ Breadth. Rostrum Length ÷ Breadth. Rostrum Length in Body Lenght. Rostrum Spines. 6. Length in Body Length. 7. Squame ÷ Peduncle.
Mm.
Ross 125 1.90 1.80 7.70 4-4/0 8.8 0.85
Greymouth 90 2.19 2.29 6.08 4-4/2 7.5 0.98
Murchison 50.4 2.44 1.74 6.90 4.5-4.5/0 9.7 0.73
Aorere River 64 2.19 2.08 6.60 4.5-4.5/1 7.3 0.98
Wakefield 62 1.94 2.15 6.60 4-4/1.5 7.1 0.89
Brightwater 71 2.11 2.35 6.10 4-4/1.5 7.0 0.91
Richmond 99 2.24 2.12 6.80 4-4/1 7.7 1.30
D'Urville Island 62 2.08 2.70 6.01 5-4.5/2.6 5.4 1.30
Pelorus River 65.5 2.48 1.79 7.50 5-5/0 9.3 0.80
Kenepuru 49.5 2.26 1.66 8.30 5-3/0 9.7 0.77
Spring Creek 89 2.21 2.80 8.50 4-4/2 6.5 1.08
Ocean Bay 83.7 2.11 2.10 7.30 4.5-4.5/3 8.2 0.90
Wellington 58.7 2.13 1.95 6.90 5.5-4/1 8.4 0.93
Kapiti Island 76 1.94 2.30 6.60 4-4/1 8.0 1.00
Masterton 49.2 2.21 2.37 5.70 4-4/2 6.8 1.07
Wanganui 88.6 2.19 2.60 6.40 4-4/2 7.0 1.14
New Plymouth 82.6 2.08 2.32 6.30 4-4/1 7.1 1.00
Hawke's Bay 87 2.02 2.44 5.90 3.5-3.5/2 6.1 1.02
Napier 125 1.91 2.22 6.02 4-4/2 5.1 1.00
Rotorua 66.2 2.02 1.95 6.62 4-3.5/1 7.7 1.02
Rotoiti 92.7 1.98 2.25 6.30 4-4/1.5 7.1 0.96
Puriri 65.2 2.26 2.00 6.52 3-3/1 6.7 1.00
Manukau 77.5 2.16 2.67 5.10 3-3/1 5.8 1.12
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Table 2.—Average Measurements of Specimens of P. setosus.
Column No. 1. 2. 3. 4. 5. Antennal Scale.
Specimen. Average Length. Carapace length ÷ Breadth. Rostrum Length ÷ Breadth. Rostrum Length in Body Length. Rostrum Spines. 6. Length in Body Length. 7. Squame ÷ Peduncle.
Mm.
Rangiora 86.5 2.03 1.90 7.0 4.5-4/1 8.3 0.98
Waimakariri River 79.7 2.03 2.16 6.2 5.5-5.5/1.5 7.3 1.03
Styx River 35 2.25 2.03 5.9 4-4/2 6.3 1.20
Avon River 109.1 1.72 2.07 6.7 4-4/2 7.6 0.98
Peel Forest 78 2.02 1.92 7.0 4.4-4.5/1 8.6 0.91
Winchester 103 1.95 2.00 6.0 5-4/1 7.0 0.99

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Table 3.—Average Measurements of Specimens of P. zealandicus.
Column No. 1. 2. 3. 4. 5. Antennal Scale.
Specimen. Average Length. Carapace length ÷ Breadth. Rostrum Length ÷ Breadth. Rostrum Length in Body Length. Rostrum Spines. 6. Length in Body Length. 7. Squame ÷ Peduncle.
Mm.
Tinwald 138 1.82 1.70 7.5 5-5/2 8.6 0.85
Waimate 100 1.89 1.68 7.6 3.6-3.8/1 8.8 0.85
Glenavy 100.7 1.94 1.71 8.1 4.5-4/0 8.4 0.87
Oamaru 59.7 2.00 1.54 7.0 5-5/2 7.8 1.00
Waitati 54.5 2.14 1.79 7.6 5-5/0 8.1 0.96
Dunedin 120 1.99 1.85 7.7 5-4/0 9.2 0.83
Clifden 130 1.94 1.84 7.4 5-4/2 8.7 0.90
Wyndham 97.6 1.98 1.62 7.6 5-5/1.2 13 0.78
Picture icon

Fig 1—Paranephrops planifrons
Fig 2—Paranephrops setosus
Fig 3.—Paranephrops zealandicus.

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Bibliography.

Chilton, C. 1883. “On. some Points of Difference between the English Crayfish. (Astacus fluviatilis) and a New Zealand one (Paranephrops setosus).” Trans., N.Z. Inst., vol. 15, pp. 150–65, pl. 19–21.

— 1889. “The Distribution and Varieties of the Fresh-water Crayfish of New Zealand.” Trans. N.Z. Inst., vol. 21, pp. 237–52, pl. 10.

— 1900. “Note on the Fresh-water Crayfishes of New Zealand.” Trans. N.Z. Inst., vol. 32, pp. 13–17.

Dana, J. D. 1852. U.S. Explor. Exped., xiii, Crust., pt. 1, p. 527.

— 1853. U.S. Explor. Exped., Crust., Classification and Geographical Distribution, p. 1433.

— 1855. U.S. Explor. Exped., Atlas, pl. 33, fig. 4.

Faxon, W. 1898. “Observations on the Astacidae in the United States National Museum and in the Museum, of Comparative Zoology, with Descriptions of New Species.” Proc. U.S. National Museum, vol. 20, pp. 643–94, pl. 62–70.

Filhol. 1885. “Mission de l'île Campbell: Passage de ‘Venus’ sur le Soleil,” 9th Dec., 1874. Institut de France, iii, 2nd part, No. 1, p. 429.

Hutton, F. W. 1873. “Description of a New Species of Fresh-water Crayfish from New Zealand.” Ann. Mag. Nat. Hist., 4th ser., vol. 12, p. 402.

Lenz, H. 1901. “Ergebnisse einer Reise nach dem Pacific (Schauinsland, 1896–97), Crustaceen.” Zoolog. Jahrb., vol. 14, 1901, p. 441.

Miers, E. J. 1874. Zool. “Erebus” and “Terror,” Crust., p. 4, pl. 3, fig. 1, and pl. 2, fig. 2.

— 1876. “Catalogue of the Stalk- and Sessile-eyed Crustacea of New Zealand,” pp. 72–74.

Newbigin, Marion I. 1898. “Colour in Nature,” pp. 117–29.

Semper, K. 1899. “The Natural Conditions of Existence as they affect Animal Life,” 5th ed. The International Scientific Series, vol. 31, pp. 160–61.

White. 1842. Gray's Zoolog. Miscellany, No. 2, p. 79.

— 1843. “Appendix on the Fauna of New Zealand, in Dieffenbach's Travels in New Zealand,” ii, p. 267.

— 1847. Proc. Zool. Soc., London, pt. 15, p. 123.

— 1847. “List Crustacea, British Museum.”

— 1848. “Descriptions of New or Little-known Crustacea in the Collection at the British Museum.” Ann. Mag. Nat. Hist., 2nd ser., vol. 1, p. 225.

Wood-Mason, J. 1875. “Note on the Geographical Distribution of the Temnocephala chilensis of Blanchard.” Ann. Mag. Nat. Hist., 4th ser., vol. 15, p. 336.

— 1876. Proc. Asiatic Soc. Bengal, p. 4.

Explanation of Plate IV.

Fig. 1. Paranephrops planifrons White. Lake Rotoiti, Auckland.

Fig. 2. Paranephrops setosus Hutton. River Avon, Christchurch.

Fig. 3. Paranephrops zealandicus (White). Dunedin.