Annals and Magazine of Natural History Series 8

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XLIII.—The of , a genus of wood- boring

Chas Chilton M.A. D.Sc. LL.D. M.B. C.M. F.L.S.

To cite this article: Chas Chilton M.A. D.Sc. LL.D. M.B. C.M. F.L.S. (1914) XLIII.—The species of Limnoria, a genus of wood-boring Isopoda , Annals and Magazine of Natural History, 13:76, 380-389, DOI: 10.1080/00222931408693499

To link to this article: http://dx.doi.org/10.1080/00222931408693499

Published online: 15 Sep 2009.

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XLIII.--The Species of Limnoris, a Genus of Wood-bor(,g lsopoda. By Cnxs. CHILTOS, M.A., D.Se., LL.D., M.B., C.M., F.L.S., Professor of Biology, Canterbury Colleg% :N.Z. [Plate XYII.] O~ July 29th, 1913, I received from the authorities of tile Auckland Harbour Board a piece of timber that was being destroyed by a marine borer, with the request that I would see if the borer was the "," Limnoria llgnorum, Rathke. An examination at once showed that the borer was certainly a species of Limnoria ; the decision as to whether it was the European species or not required some care, as in 1883" I had described from Lyttelton Barbour, New Zealand, another species, Limnorla segnls, which in general appearance was extremely like L. lignovum , though differing from it in the characters of some of the mouth- parts and living on seaweed instead of boring into wood. A detailed examination and a comparison with specimens from Plymouth, England, showed, however, that the boring into the wood in Auckland Harbour was indeed L. lignorum. This conclusion, moreover, was confirmed by the fact that, accompanying the Limnoria~ there were also some specimens of an Amphipodan borer; which, on com- parison with specimens fi'om Plymouth, England, proved to to be identical with Chelm'a te~'ebrans, Philippi, r a species associated with Limnoria liynorurn in Europe J'. I hese two species must evidently have been introduced into New Zealand, probably in some old wooden vessel, and they thus afEord an example of the accidental dispersal of marine Crustaeea by means of ships, additional to those already recorded by me (1911, p. 131). It cannot be ascertained for certain how long ago these two Crustaeea were introduced into Auckland Harbour, but Downloaded by [University of Florida] at 01:25 20 June 2016 in all probability it was many years ago. 2'hey appear to find the locality favourable, for they were extremely numerous in the samples of wood that were sent down to me, and they seem to be causing rapid destruction, both of the softer timbers, such as Kauri, and even of harder kinds, such as Totara. * The references are made by the year of publication to the list at the end of the paper. ~f It should be remembered that at Christmas Island, Indian Ocean, another species, Zimnoria andrewsl, is associated with a different species of Chdura, i. e. C. insul~e~ Caiman (see Calman, 1910~ p. 182). t~e ~mle~t ~Lim~ia. 351 To ascertain if tile Lfmnorla o~red elsewhere in New Zealand, l applied to Mr. Cyrus Williams, ~ngine~r to the Lyttelton Harbour Board, who most obligingly sent me a specimen of an ironbark pile, tile outer part of which was partially destroyed. Examination showed that this destruc- tion also bad been caused by Limnorla liynorum, though in this particular case it appeared to be unaccompanied by Chegura terebrans. Mr. Williams stated that in Lytteltou Harbour tlle animal could perhaps hardly be called a borer, as it seemed to operate only on tile surface, removing about one inch from the outside of an ironbark pile in about thirty years, though with softer timber its operations were much more rapid. Later on, in December 1913, I found the same species, Limnoria lignorum, boring into piles in Akaroa tiarbour, though here again it did not appear to be accom- panied by the Chelura. Probably it will be found that L~mnoria lignorum has bean similarly introduced into many other harbours. In a paper on the marine wood-borers of Australia, read at tile Melbourne Meeting of the Australasian Association for the Advance- ment of Science, in January 1900, Mr. Chas. Hedley (1901, p. 237) stated that neither Limno~'ia ligno~.um nor Chelura terebrans had up to that time been recorded by naturalists from Australasian seas, but in a footnot% added on the 14th Jun% 1901, as his paper was passing through tim press, he states that Mr. T. Whitelegge had identified L. Uynorum from timber fi'om a floating jetty at Circular Quay, and again from part of the hull of a ferry-boat plying in Sydney Harbour. In the timber, both from Auckland and from Lyttelton, I found, along with the Limnoria, numerous specimens of another Amphipod, ~' CoroThlum contractum," G. M. Thom- son (1881, p. 220). The CoroTMum, however, did not appear to be boring into the timber, but to be merely taking advantage of the decay caused by the Limnoria, and thereby Downloaded by [University of Florida] at 01:25 20 June 2016 securing a suitable dwelling-place and probably also food. D,'. Macdonald has (1875, p. 67) described a similar associa- tion in England, where Tanais vittatus was found in the holes bored by Limnoria lignorum and Chelura terebrans. In this paper I do not propose to deal with the borer from the economic aspect; some details of the damage done in Australasia by these Crustacea and by other borers is given in Mr. ttedley's paper. The examination of the specimens, however, necessitated a comparison with L. segnis, a species which does not bore into wood, but lives on seaweed, patti- 382 Dr. C. Chilton on cularly on the bmnchlng holdfasts of Maceocystls. This rendered necessary also an examination of the characters of the other species of Limnoeia that have been described during recent years, and has led to one or two results which are perhaps worthy of being placed on record. I have had for examination numerous specimens of L. lignorum and of L. segnis , and I have also been able to examine two speci- mens from the South Orkney Islands which appear to belong to L. antarctica, Proffer. These were found among tile "residues" of some Amphipodan collections made by tile 'Scotia' Expedition ill 1903, and were presumably taken free, i. e. not boring into wood. In 1904~ the Rev. T. R. R. Stebbing (1904, p. 714) enumerated four species known at that time, with the characters that appeared to distinguish them. Since then two other species have been described, making six species in all. These species are :-- I. Limnoria lignorum (Rathke), 1799. Length 5 mm. Wood-borer, abundant in Europe and on the eastern coast of :North America, also recorded from tile Pacific and from San Diego, California. 2. L. segnis, Chilton, 1883. Length 5 ram. Speeie~ living on seaweed and not boring into wood~ Lyttelton and Akaroa ]ffarbom's, New Zealand. 3. L. antarctica, Pfeffer, 1887. Length 4:'5 ram. Found in holes bored in seaweed, South Georgia; also taken at the South Orkneys. 4. L. pf~fferi, Stebbing, 1904. Length 3"5 mm. Found in rotten wood in lagoon, Minikoi, Indian Ocean. 5. L.japonica, Richardson, 1909. Length 5 mm. Taken from crevices in water-logged fragment of bambo% Japan. 6. L. and~'ewsl, Calman, 1910. Length about 2 mm. Boring in piles, Christmas Island, Indian Ocean. Downloaded by [University of Florida] at 01:25 20 June 2016 These six speeies form a very natural group, and are all very much alike in size, general appearance, and in the general form and structure of the different appendages. They seem to differ mainly in the proportions of some of the mouth-parts and of the other appendages. The chief points that have been used to differentiate them are the shape and size of the epipod o£ the maxillipeds, the character of the palp of the mandible, the relative size of the rami of the uropods and their proportion to ttte peduncle, and the presence or absence of a comb-like spine on the propod of the first gnathopod ; other distinctions lmve in certain eases the gpeeies of Limnoria. 383 been drawn from the shape of the body, the propotgions of its dit~erent segments, and the presence or absence of tubercles on the dorsal surface of the pleon. Lfmnoris l;9norum has been fully described by Harger, Sars (1897, p. 76), and others, and its characters are pretty well known. L. antarctlea was described in great detail by Pt'efFer in 1887, and in the descriptions of L. pfeff~i and L. andrewsi special notice has been taken of the characters distinguishing the species. Of L. segnis only the short original description has been published, and it will be con- venient to consider its characters here somewhat more fully attd with special reference to the points mentioned above.

Limnoria segnis , Ohilton. Limnoria s~nis, Chilton, 1883, p. 76, pl. iL fig. 1; Stobbing, 1904, p. 714. General Description and Comparison wit)i otI~er 8peeies.~ The general appearance is. in close agreement with L. lig- no'rum, though the body is usually slightly broader and more convex and looks rather more compacls. The whole surface is thickly covered with short setup, with some longer ones, especially on tire margins of tile segments. The body is generally of a dull white or cream colour, and does not show the grey markings usually present on L. li#norum. As in that species and in L. pfefferi the head is almost globular and is narrower titan the rest of the body ; the first segment of the permon is longer than any of the succeeding, but I have noL noticed on it the conspicuous dorsal V-shaped grooving described by Stebbing for L. pfefferi; the s~de- plates agree generally with those of L. lignorura, and the same is true of the pleon and the terminal segment. The fifth segment of the phon is much longer than any of tile four preceding, especially in file median line, and in Downloaded by [University of Florida] at 01:25 20 June 2016 dorsal view it shows the shape as drawn by Pfeffer for L. antarctica ; it bears a faint median ridge. On the last segment~ near its anterior margin, there is a slight median elevation or tubercle, from which extend posteriorly two faint parallel ridges. These markings are visible only in speci- mens ttmt have been dried, and even then, owing to the short sett~ covering the general surface of the body and the extraneous matter entangled in them, they are not always very distinct, especially in smaller specimens; they are, l!owever, interesting as showing some approach t'o the tubercles and ridges dese, ibed by ]Kiss Richardson in 384 Dr. C. Chillon on L.japonlea. In side view the small tubercle on the last segment presents pretty well tile appearance shown by Pfeffer in his side view of L. antaretiva. The upper antennae have the second joint subequal with the first and slightlylonger than the third, the flagellum is represented by two or three small joints bearing long olfactory setup. I have not seen anything corresponding to the small nodule described by Oalmau (1910, p. 18~) as perhaps representing a vestige of the inner flagellum. The second antenme do not differ appreciably from those of L. lignorum. In the mouth-parts, the mandibles (PI. XVII. fig. 1) differ distinctly fram those of the other species in having the pulp quite small and composed of two subequal slender joints, tile terminal one of which bears two or three small set~o at tile extremity. The body of the mandible appears to be very similar to that of L. lignorum, and ends in a fine sharp cutting-edge, which shows no division into separate teeth ; on the outer portion between the cutting-edge and the pulp is a strong subacnte projection as in L. llynorum, and on the inner side there is tile usual row of setm, though apparently no trace of the molar tubercle. Tile cutting-edge of the mandible in L. lignorum is usually shown as entire and not divided into teeth ; m one specimen, however, that I examined there are faint indications of its division into three teeth ~,fig. 6). In this specimen, too, the inner surface below the cutting-edge was covered with small, closely-set, imbricating teeth forming an efficient rasping organ ; probably the same structure is common to other specimens, but it is rather difficult of observation, and I failed to detect it in some specimens examined, though it is quite distinct in the one figured. Tile first and second maxilla~ are essentially the same as those of L. lignorum, except that the first maxilla appears to be slightly shorter and stouter. Downloaded by [University of Florida] at 01:25 20 June 2016 In the maxillipeds (fig. 2) tile epipod reaches beyond the end of the second joint and is rounded at the end, slightly narrowed towards the base, and its greatest breadth is about one-fourth the length ; the whole margin of it is fringed with small finely plumose sette. In other respects the maxilliped is hardly distinguishable from that of L. llgnorum. The first pair of legs (figs. 3 and 4) resembles that of L. ligaorum, and the accessory spine on tile inner side of the dactyl is bidentate as in that species, its smaller ~ooth being of minute size : in L. aadrewsi, Caiman, the accessory spine is tridentate ; from tile distal end of the propod ghere springs Downloaded by [University of Florida] at 01:25 20 June 2016

f

0 r- ~~ z 0

.~ ~ the Speo[es of Limnorla. 385 a large spine wlth a sing|e row. of comb-like teeth, similar to

the one described b Y Calman m. L " andrewsi • I find~ how- ever, that this comb-like spine is present also m L. lignorum and in L. antarctica. Tile metal and carpal joints and tile base of the propod bear small blunt tubercles~ similar to those in L. l[gnorum, though less prominent. Tile remaining legs appear to be similar to those of L. liffnorum, and as in that species the accessory spine on the inner side of the dactyl is simple. The metal and carpal joints of the anterior legs are provided with blunt spines or tubercles as in the first pair. Calman states that in .L. andrewsi none of the distal segments are provided with tubercles or blunt spines ; the development of these tubercles in the specimens of L. segais and of L. lignorum that I have examined seems to be subject to some varlation~ as they are sometimes more prominent than others, and they appear to be best marked in the larger specimens ; Oalman~s specimens of L. andrewsi were only about 2 ram. in length, and their small size may account for the absence of these tubere!es. The tubercles are present in L. antarctica and apparently also in L. pfe]eri ; indeed, all the permopoda of the last species, as described by Stebbing~ seem closely similar to those of L. h~qnorum and L. segnis. In all the species all the legs ar~ provided with prominent pectinate spines, similar and similarly arranged to those in L. lignorum ; these doubtless serve some useful purpose in connection with the life of the animal, though it is not easy to see what their precise function is. Tile pleopoda do not appear to differ from those of L. lignorum ; the last pair has the margins of both plates free from set~e. The uropoda (fig. 5) have the inner ramus slightly shorter than the stout peduncle and ending in a tuft of long set~e ; the outer ramus is small, curves downwards~ and has the extremity unguifbrm; the peduncle is produced between the rami into a subacute projection. The peduncle bears on the lower side, near its outer margin, a longitudinal Downloaded by [University of Florida] at 01:25 20 June 2016 row of long plumose set,e, as in L. lignorum and L. pfefferi, but has the outer margin almost smooth instead of being tuberculated as in L. lignorum; in some specimens of that species that I have examined, however, these tubereulations are by no means distinct. In his table giving the distinctions between the species, Stebbing describes L. llgnorum as having the outer ramus of tlle uropods ~t unguiform," and thus distinguished from the o~her species in his list (L. seqnis, L. antarctica, and L. pfefferi), in which it is not unguimrm. Whether the outer ramus in L. seqnis should be called " unguiform" or not is largely g matter of definition, but if, Ann. & Mag. N. Hist. Ser. 8. Vol. xiii. 27 386 Dr. C. Chilton oa seems to me to be quite as unguiform as in most of the specimens of L. lignorum that I have examined. A comparison of the uropoda of tile species at my disposal shows that tile structure is essentially the same throughout and that the resemblances are very close, closer than might be anticipated from a comparison of the figures given by different authors. In all three the peduncle bears on the under surface, at some little distance from the outer margin, a longitudinal row of long, finely plumose hairs ; otimr hairs of more unequal length fringe the actual margin. The end of the peduncle is produced on the underside into a small subacute triangular process between the bases of the rami. The inner ramus is much the longer and bears at the extremity, which is usually truncate, a tuft of long sette, about as long as the remus itself; other seta~ may be present on the outer margin, but the inner margin seems in all cases almost free from seta~. The inner ramus is short ; it curves outwards and ends in a nail, at the base of which, on the concave side, is a tuft of about three seta~ which reach beyond the end of the nail. In L. l~:qnorum the outer margin of the peduncle usually bears a number of small tubercles or small blunt spines. I have, however, failed to find these in some of the Auckland specimens, in which the outer margin is slightly roughened only; in these specimens the uropod is hardly distinguishable from that of L. scynis (compare figs. 5 and 7). In the specimens from South Georgia, which, I have no doubt, must be referred to L. antarctica, Pfeffer, the outer margin of the peduncle (fig. 8) shows slight evidence of tuberculation ; both rami are short, ~hough not quite so short as is shown in Plotter's figure, taken from South Georgia specimens, and in one specimen, a small one, it has a nail at the end quite similar to that in L. lignorum, though smaller. In L. pfefferi the figure given by Stebbing shows that the peduncle is the same as that in L. lignorum or L. segnls, and Downloaded by [University of Florida] at 01:25 20 June 2016 it is probable that the whole uropod of L. l?fefferi is practi- cally the same as in these two species. The uropoda of L. andrewsi, as drawn by Caiman, have a short peduncle and look rather different from those of the other species, but his figure is too small to show the details referred to above.

From the foregoing account it will be seen that there is a very great resemblance between all the species, both in general appearance and also in more minute characters of the various appendages; they constitute a well-marked genus, which occupies an isolated position under the Sph~romid~a. tl~e 8pedes of Limnorla. 887 ~otwltlmtanding these many points of resemblance, there a~, however, some minute characters by which most of the sp~eiescan be distinguished. The most important of these seem to me to be the characters of the mandibles and the maxillipeds. Tile exact relationsllips of the species seem rather difficult to disentangle, but the species may readily be distinguished in the following way :--

,4rt~ficlal Key to the Species. J Palp of mand~le two-jointed ...... L. segnis. 1. ~Palp of mandible three-jointed. 2. Epipod of maxilliped shorter than second o-J joint ...... ~,li#narura. "" ~F,,pipod of maxillipod longer than second t joint. 3. t Body with prominent tubercles on pleon .... L.japonica. • I Body without prominent tubercles on pleon. 4. (Peduncle of uropoda shorter than inner ramus. L. andrewd. 4.~Pedunele of uropoda longer than inner t. ramus. 5. I Both rami of uropods very short ...... 7",. antarctica. 5. Inner ranfi of uropods not very short ...... L. pfe~eri. The order in which the species are given in this artifi- cial key does not correspond with their true relationships ; the following tree represents my idea of their probable origin --the position of L. japonica is, however, uncertain, as no definite iiiformation as to its mouth-parts is available :--

*egnia. L. ~taretiea. L. pfefferi. L. andr~si. L. lignom~n. L.japonica. Downloaded by [University of Florida] at 01:25 20 June 2016

It is always imporLant to connect the characters by which species of a genus are related to one another with their 27* 388 On the ~pec~es of Limnorla. geographical distribution, and, in the case of Lemnor~a, it seems possible to find some connection begween the species and their distribution. Thus L. se.qnis, which has probably been long separaged, geographically, from the other species, is distinctly marked off fi'om them by its very small two- jointed mandible. L. llgnorum, which is found in the north, also far removed from most of the other species, shows dis- tinct differentiation from them in the small size of the epipod of the maxillipeds; of L.japonica we have unfortunately no information as to the mouth-parts, but from the description it appears that it is closely related to L. lignorum, differing only in the possession of tubercles on the pleon~ and it may be anticipated that its mandible will be found to be three- jointed and the epipods of tile maxillipeds to be short; it comes fi'om Japan, not so very far from ttle Pacific Coast of Americ% from which L. lignorum has been recorded. The remaining three species seem more closely connected with one another, both in structure and in distribution; there is little essential difference in their mouth-parts, and it is difficult to say whefller they can continue to be considered as distinct species when forms from intermediate localities have been found. .L. antarctica appears to be fairly well marked off from tile other two by the small size of both rami of the nropoda, and .L. andrewsi may be distinguished fi'om L. pfefferi by the shortness of the peduncle of the uropoda ; though these characters are proportional only. and may perhaps be found to vary with the age of the spemmen. All the species, except L. segnis and L. antarctic% appear to be wood-borers, and it seems likely therefore that tile wood-boring habit is characteristic of the whole genus and that some of the characters of the animal, such as the small size of the body and the shortness of the antennte and tile per~eopoda, are associated with the wood-boring habit. The wide distribution of the various forms and their small amount of difference may therefore be accounted for by their dis- Downloaded by [University of Florida] at 01:25 20 June 2016 persal by means of floating logs into which they were boring ; if this is so, then the two species wlfich are not now wood- borers must have lost the wood-boring habit through being cast on some shore where wood for boring was not available, and having had to adapt themselves to another mode of life. It is possible that this occurred on the Antarctic Continent~ and that L. segnis has reached ~qew Zealand by way of the Antarctic Continent, and in doing so has had the mandibular palp more reduced than it is in L. antarctica (the species to which it is probably most nearly allied) and in the species living in the Indian Ocean. On D,'. D. O. Elliot's' Revieua of the Primates.' 389 .~e~6rence8° C~LMA~, W.T.--1910. 'On Two new Species of Wood-borlng Crustacea from Christmas Island.' _&an. & Mug. Nat. Hist. ser. 8. eel. v. pp. 181-186, pl. v. CHILTON,C.--1883. ' Further Additions to our Knowledge of the New Zealand Crustacea.' Trans. N.Z. Inst. eel. xv. pp. 69-86~ pls. i.-iii. CHILTON', C.--1911. ' Note on the Dispersal of Marine Crustacea by means of Ships.' Trans. N.Z. Inst. eel. xliii, pp. 131-133. HEDLEY, C.-- 1901. ' The Marine Wood-borers of Australasia and their Work.' Rep. Australasian Association for the Advancement of Scienc% eel. viii.pp. 237-255. MAC])ONALD, J.D.--1875. 'On the External Anatomy of Tanais vit2atus~ occurring with JLim~ora and Chelura in excavated Pier- wood.' Trans. Linn. See., Zool. ser. 2, eel. i. pp. 67-71, ~)1. xv. PFEI~FER, G.--1887. ' Die Krebse yon Siid-Georgien.'l. Tell. Jahrb. d. wiss. Anstalten zu Hamburg, eel. iv. pp. 1-100, pls. i.-vii. RmHARDSON, HAttRIET.--1909. ' L~opods collected in the North-west Pacific by the U.S. Bureau of Fisheries' Steamer "Albatross" in 1906.' Prec. U.S. Museum, eel. xxxvii, pp. 75-1'29, with text- figures. SARS, G.O.--1897. ' An Account of the Crustacea of Norway/eel. ii. Isopoda, parts iii. & iv. STEBBX~G, T. R.R.--1904:. t Marine .--XII. Isopoda.' Fauna and Geography of the Maldive and Laccadive Archi- pelagoes, eel. ii. part 3. THOMSOn, G.M.--1881. ' Recent Additions to, and Notes on. New Zealand Crustacea.' Trans. N.Z. Inst. eel. xiii. pp. 204-221~ pls. vii. & viii. EXPLANATION OF PLATE XVII. l~ig. 1. Zimnoria segn~ : mandible. × 100. Fig. 2. ,, ,, maxilliped. X 100. F/g. 3. , , first leg. X 80. ~'g. 4. ,, , extremity of first leg~ more highly magnified. • ~g. 5. ,, , uropod. × 100. _Fig. 6. Z~rnnarla llgnorum : extremity of mandlbl% innc~ side. X about 275. Fig. 7. ,, ,, (specimen from Auckland Harbo~r) ; UrOl)od. x 100. ~i#. 8. Limnoria antarctica : uropod. X 100. Downloaded by [University of Florida] at 01:25 20 June 2016

XLIV.--Some Remarks on Dr. D. G. Elliot's ' Review of the Primates.' By HgRBEttT C. ROaINSON, C,M.Z.S., and C. Boron KLoss, F.Z.S.

TH~ American Museum of Natural History has recently published, in three bulky and handsomely got-up quarto volumes, 'A Review of the Primates'a, by the veteran Monographs of the American Museum oi Natural History, Mono- graph Series, Volumes I.-llI. ' A Review of the Primates/ by Daniel Gh'aud Elliot. Now York, U.S.A., June 1913.