PART III ANTARCTIC KOTIFERA BY JAMES MURRAY AMONG the various forms of freshwater life the Rotifera were most conspicuous. They were found among mosses and in the lakes and ponds. In the former situation they were relatively scarce, while in the lakes they were extremely abundant, and were often associated in such numbers as to affect the colour of the water. Some sixteen species were distinguished, representing three of the recognised orders, and five or six distinct families. The predominance of the Rotifera was entirely due to the Bdelloida, of which a dozen species were found. In the other orders there were only one or two members of each family present. Five of the Bdelloids are species previously unknown. Most of the others differ more or less from the types of their species. Only two non-Bdelloids species were recognised (Hydatina senta and Diaschiza tenuior), the others were only assigned to their genera. No Rotifera were found in the sea. I have been able to find no record ofany species of rotifersfound on the Antarctic Continent or on any of the islands which, though lying outside the Antarctic Circle, possess a polar climate. The German Expedition found Rotifers on the Gaussberg, just on the Antarctic Circle (Richters, 31) * the Swedish Expedition obtained them ; at Snow Hill Island, not far from the Circle (Richters, 32), and the Scottish Expedi- tion at the South Orkneys, a little farther north (Murray, 26).t All of these were unrecognisable. The only species doubtfully identified from this whole great area is Callidina papillosa, Thomp. (40). Richters found an egg in moss from the Gaussberg which resembled the egg of C. papillosa figured by Jansou (20). The identification of this egg can never be certain, as there are several other Bdelloids which have similar eggs, covered with blunt processes. To find definite records of Rotifera in the southern hemisphere we must go far * Figures in heavy type enclosed in brackets refer to list of books at the end of the paper. t The Rotifer vulgaris casuallyrecorded in that paper must be regarded with doubt. As all the others were dead, it had probably been accidentally introduced into the bottle. BRIT. ANTARCT. KXPED. 1907-9. VOL. I. PART 3, ISSUED APRIL 1910 F 42 JAMES MURRAY A beyond the Antarctic Region. few species have been found in Gough Island (Murray, 29), and Amsterdam Island (Richters, 31). Hilgendorf (19) has published a list ofover forty species from New Zealand, in about latitude 43 S., and these are- the nearest neighbours to the Antarctic Rotifers of which I can find any notice. BDELLOIDA Order PHILODINAD^E Family Genus Philodina Philodina gregaria, sp. n. (Plate XL, Figs. 7a7e) Specific characters. Large, corona large, narrower than trunk, wider than collar, space between discs wide, the rounded lobes springing from collar large, the interspace with two smaller convexities ; collar very prominent, but scarcely marked off from pedicels; rostrum shortand broad; antenna short; eyeslarge, pale brown; teeth 2+1/1+2;- foot offourjoints, spurs slender, acute, moderately divergent, separated by broad flat interspace; viviparous; found aggregated in great numbers, forming larger or smaller patches. Detailed description. Size variable^; smallest about $ inch long, in the feeding attitude (= 416 M) ; longest measured inch (= 800 /*) when fully extended creep- ing : a fairly large example had the following measurements, diameter ofcorona y^ inch (= 166 yu), of collar y^ (inch = 132 /*), of neck -^ inch (= 106 /*), of trunk yyT inch (= 213 ft), length of jaw ^fa inch (=* 47 M). of spur ygVs inch (=25 /*). Central setae were not detected on the discs. The very prominent collar passes insensibly into the pedicels, the junction marked only by the line of fine cilia (secondary wreath). The rostrum bears short lamellae, a brush of active cilia, and four stout straight setae, corresponding to the tactile setae ofP. brevipes (25) and some other species, but they were not seen in motion. The length of the antenna is about equal to half the diameter of the neck segment which bears it. The brain is fairly large. Each jaw bears two strong teeth and one thin one, and in addition the usual fine striae. There is a prominent hook at thebackof the ramus. The stomach is very voluminous, and of a very bright deep ruby or crimson colour, due to the presence of coloured granules and globules. The central trunk is the broadest part of the body, and varies in size with the number ofyoung carried. It is- regularly plicate, the folds shallower on the back, deeper on the sides. The reproduction is viviparous. Usually there are two or threeyoungcarried at a time. Whatever the number, they appear to be all at the samestage ofdevelopment. At any rate they are all ofthe same apparent size, and after the jaws are developed they appear to be alike in all. It is very different with the genus Rotifer, in which. ANTARCTIC ROTIFERA 43 the young areobviously ofverydifferentages, one being fully developed while another shows no detail at all. The yolk mass contains eight nuclei. The spurs vary greatly in size,generally most closely resembling thoseofP. acuti- cornis (25). The interspace is relatively broader. Occasionally they are very long and apparently two-jointed. The last foot-joint is long. The ventral toes are very and the dorsal ones very small. large, The vibratile tags are short, and broadly spindle-shaped. Three pairs have been seen. Habitat. In lakes and ponds at Cape Royds, Cape Barne, and at the Stranded Moraines on the west side of McMurdo Sound. It was absent from the very saline Green Lake, but was in nearly all the other waters examined. It was much the most abundant species in the district. Its abundance in Coast Lake and in the lake at the Stranded Moraines was remarkable. In winter it was got by digging out ice from the lakes. As soon as these were thawed the rotifers were containing plants found active in great plenty. In summer blood-red patches began to form on the stones at the margin of Coast Lake. These attained to a diameter of an inch. Similar patches were on the plants, but these were more difficult to detect owing to the orano-e-red colour ofthe plants. In the lake at the Stranded Moraines, Priestley reports that the patches reached to six or eight inches in diameter, and were of appreciable thickness. These patches were formed solely ofP. gregaria, which were fixed side by side, as close as they could stand. To obtain them a handful of weed was taken and washed in a bucket ofwater, being vigorously shaken in order to detach all the adherent microscopic organisms. The sedimentthus obtained was strainedthrough acoarse silk net, in order to remove the larger particles, and thefine sediment was thenbottled and allowed to settle. At first it was ofa dull green colour, from the preponderance of blue-green Algae. After an hour or two a red film, like blood, appeared onthe surface of the mud. The rotifers have crept out of the mud. After a time they leave the mud and creep up the sides of the bottle intothe clear waterabove eventually they reach the surface ofthewater ; and there form a ring of red round the bottle. They may then be collected in thousands with a brush and put into clean water. This process may be continued with one lot for days, an hour or two being sufficient time for new hosts ofthe endless procession to reach the surface. Habits. P. gregaria is ordinarily rather a restless animal. It is ready enough to feed, and remains fixed in one spot for a long time, but it swings about continually so that it is not easy to get a good portrait. Though normally anchoring itself, in company with its myriad neighbours, it occasionally casts off" and goes swimming. In Coast Lake it was got in the tow-net, and a few might be seen if a bottle ofthe lake water was held up to the light. According to Priestley it was much more plentiful in the water of the lake at the Stranded Moraines. It was particularly amenable to treatment with mild narcotics. When a very 44 JAMES MURRAY dilute solution of Eucaine was added to the water, it at once changed both habits and appearance. It ceased its restless swaying about and went on feeding so steadily that it could easily be photographed. The circular muscles were slightly contracted, thus deepening the constrictions between the principal divisions of the body. The foot was inclined to be further retracted than in the normal condition. Otherwise there was little change in form, and the corona was quite unaltered. The effect of the narcotic was much less than on P. laticeps. When that species is treated with Eucaine it partially retracts the foot, expands the usually narrow central trunk, and reduces the width of the corona, in fact it so completely alters its proportions that it is not recognisable for the same species, and might be mistakenforsome speciesofthe central group (P. citrina, P. brevipes, &c.) unless particular attention were paid to the spurs. Affinities. P. gregaria belongs to the central group of the genus, possessing eyes and tapering spurs of moderate size. There is nothing distinctive in the general form. The viviparous reproduction distinguishes it from all the species ofthatgroup. The red colour is differently distributed from that ofP. roseola, in which the red is diffused. In this species it is limited to the stomach. The slender spurs, with broad interspace, are like those of P. laticeps and P. acuticornis. The short antenna separates it from both. It is of larger size than any of the other species in the central group, except perhaps P. citrina. The large size, red stomach, viviparous reproduction, and slender spurs set far apart, will distinguish it from all known species of Philodina. The absence of a groove between the prominent collar and the pedicels is also a good character. Natural history. As the dominant species in the lakes of Cape Royds the natural history of P. gregaria received a good deal of attention, and many experi- ments were made to elucidate it. These will not be detailed here, but a short summaryof the facts willbe given.* Its extraordinary abundance must indicate that it is possessed ofgreat powers ofresistance to all the adverse influences which would be supposed to attend upon it in such a rigorous climate, or else that it is ofremark- able fecundity. It appears to triumph in both ways. It is perhaps inaccurate to call it "gregarious." Itis found in large " flocks," but it is doubtful if they ever " flocked" together. Thegreat crowds in which theyoccur appear to arise from the rapidity with which they reproduce themselves. Several young, probably sometimes as many as six or eight, are produced at a time, and they seem to stay and fix themselves where they are born. Thus the patches increase till they reach inches in diameter, and as there is not foothold for all, they stand on one another's heads (so to speak) till a layer of measurable thickness is produced. They withstood all the tests applied toAdineta grandis except the heating, which was not tried on them. They are normally frozen in the ice of the lakes for the greater part of the year, and revive at any time that the ice is thawed. When dried and exposed to the lowest air temperatures for a long time, they were not killed, nor *The detailedaccount of the observations and experiments will be found in a paper on "Life under Polar Conditions," in a later number of this series of Reports. ANTARCTIC ROTIFERA 45 did they die when alternately thawed and refrozen at weekly intervals for several months. Theylived for a month insea-water and in a much more saline solution, and became active again immediately on being transferred to fresh water. They were dried while inthe Antarctic by exposing to the air till allthe ice passedoff by ablation, ' and were then conveyed by a long voyagethrough the tropics to England, where they revived within an hour of being moistened and could be seen alive in London a year after they were collected. In England they were subjected to a temperature of 78 Cent, for many hours, by Mr. J. H. Priestley, of Bristol, and survived. Philodina antarctica, sp. n. (Plate X., Figs. 5a-5c) Specific characters. Large, elongate : corona of moderate breadth, wider than the prominent collar, discs with central papilla?, each bearing several fine setae ; antenna long : teeth 2/2 : foot four-jointed, long, slender ; spurs with broad triangular basal portion, and narrow apical portion of about equal length (Fig. 5b) ; last joint of foot short, dorsal toes nearly as large as the ventral ones : pale brown eyes. Detailed description. The size is variable. The shortest measured was 380 /* in length, in the feeding attitude, and with the foot well drawn in. The longest measured 714 n, fully extended, creeping. In a large example the diameter of the corona was 96 n, of the collar 73 M, of the neck 60p., of the trunk 106 n : the length ofthe spur was 30 /x. The stomach is of a deep ruby-red colour, the anterior part of the body of a faint brown, and the foot clear and hyaline. The longitudinal folds of the trunk are deep at the sides and shallow on the back. The discs are separated by a space equal to half the diameter ofa disc. Into this come the low rounded lobes terminat- ing the collar. They are slightly separated, and the part between is convex. The collar appears two-lobed in dorsal view, and is distinctlymarked offfrom the pedicels. The rostrum is short and broad. The length of the antenna is equal to the diameter of the neck segment bearing it. The reproduction is unknown. Neither eggs nor embryos were ever seen. The yolk mass has the eight nuclei usual in the order. The vibratile tags were not detected. It was an extremely difficult animal to study, on account ofits restless disposition. It went wriggling and twisting and creeping about, often stopping to feed for a moment, but never still. There were no narcotics available when it was first found in considerable numbers, and it afterwards proved to be a rare species, and very uncertain in its occurrence. For this reason no photographs were obtained, and no specimens could be preserved. Habitat. Among plants in the ice of several lakes at Cape Royds and Cape Barne. It was never got except by thawing the ice of the lakes. Most ofthe lakes in which it lived did not melt in either of the two summers we spent in the district. Affinities. Belongingalso to thecentralgroupofspecies, thereislittle in itsgeneral proportions and characters to distinguish it from several other species. It is more 46 JAMES MURRAY elongate than most ofthem, and in that respect comes nearest to P. erythrophthalma Ehr. (15). The characteristic spurs, consisting of a narrow blunt apical portion springing abruptly from a broad conical base, will separate it from that and all other known species when well developed. Sometimes the narrow part is considerably reduced. No other member of the genus has such spurs, but very similar spurs, differing only in being sharper pointed, are possessed by Callidina hexodonta, Ber- gendal (3), formerly regarded (from the possession of cervical eyes) as belonging to the genus Philodina. The slender foot, which can be elongated much more than the drawing (Fig. 5a) shows, the lack of interspace between the spurs, and the deep red stomach are also good characters. Philodina alata, sp. n. (Plate X., Figs. 4o-4/) Specific characters. Size moderate : corona broad, diameter about equal to that ofthe trunk (exclusive of the processes) in ordinary extension ; collar inconspicuous, the lobes going to the upper lip not reaching beyond the line of the bridge joining the pedicels : interspace between discs equal to diameter of disc ; central setae on discs : teeth 2/2 : trunk plicate, bearing two large rounded lateral processes (one on each side) a little way in front of the widest part of the central segments : rump short, with a rounded boss in the middle of the preanal segment : foot short, four- jointed, spurs diverging, tapering, conical, rather blunt. Eyes brown. General description. Length 300 /t, in the feeding attitude. The stomach is of the same deep red as in P. gregaria, the colour being seated in small granules and globules. The rostrum is short and rather narrow. The length of the antenna is about equal to the diameter of the neck. On the fairly large brain are seated the pale brown eyes. The jaws are rather small, and bear two teeth each. The trunk is regularly plicate, the dorsal folds being wider and shallower than the lateral ones. The trunk is sometimes decidedly viscous, and has extraneous matter adhering to it, but this is not always so. It is sometimes quite clear. The lateral processes are not thickenings, like most of the trunk processes of Bdelloids. They are large, hollow, approximately conical protuberances, with skin no thicker than that of the trunk, unless at the extreme apex, where it is a little thicker. They are controlled by special muscles, by which the apex may be more or less pulled in and inverted, making the form truncate, as shown in Fig. 4a. Some- times, when creeping or feeding, the processes are so far inverted that they are scarcely visible in dorsal view, but this is not always the case, as shown in Fig. 4c, where they are fully extended when the animal is creeping. In complete con- traction of the animal they have their greatest projection, and are then more directed forward than at any other times. No suggestion as to the function of these curious processes has been offered. In other Bdelloids having warts on the body they are supposed to have a defensive ANTARCTIC ROTIFERA 47 function. It can hardly be so with P. alata, as the processes are, from their form, more vulnerable than the trunk wall would be. The boss on the preanal segment is of another nature. It is a thickening, and may have a protective function. The vibratile tags are short and somewhat broadly spindle-shaped (Fig. 4e). Habitat. Among weeds from the Narrows between the two portions of Blue Lake, pretty numerous, March 27, 1908. Afterwards found in several lakes at Cape A Royds and Cape Barne, always scarce and uncertain. few could usually be got when wanted from the Narrows of Blue Lake. It was living, among scraps ofweed, at a depth of 11 feet in Blue Lake. Habits. A quiet animal and slow in its movements. When feeding, which it rarely did, it could be easily studied. Under the influence of a narcotic (Eucaine) it behaved in a very unsatisfactory manner. It kept the corona expanded and continued feeding, but contorted itself till it was not recognisable except by the side processes. No good photographs of it could be obtained, but under pressure some were made which showed the internal structure and the characteristic processes. Affinities. P. alata, like the other two Antarctic members of the genus, belongs to the central group of species. The lateral processes, which are unique in the order, serve to distinguish it from all other Philodince and Bdelloids. The boss on the preanal is an uncommon character. Without these processes it would be very difficult to characterise. Philodina, sp. (Plate X., Fig. 6) Description. Size moderate. Corona narrow, about equalling the prominent collar, and less than the trunk. Upper lip with two rounded lobes meeting in the middle line. Two pale or colourless eyes. Teeth 2/2. Foot short (number of joints ?) ; spurs broad short cones slightly diverging and with no interspace. This species, which is undoubtedly distinct from all the other Antarctic species, was only once seen, and is insufficiently studied. The form of the upper lip and spurs are like those of P. plena (4). There is little to separate it from that species except the possession of eyes. It is doubtful if the presence or absence of eyes constitute characters of even specific value, as several species are variable in this respect (P. rugosa, P. macrostyla, &c.). It had not the red stomach of nearly all the Antarctic Bdelloids, but that might merely indicate youth. Habitat. Among weed from the Narrows of Blue Lake. Genus Callidina Note. The genus Callidina contains a host of species, many of them not at all closely related, and offeringmaterial for many genera. C. constricta and C. angularis 48 JAMES MURRAY in our list should le in a different genus from C. habita. As the whole order requires revision by a competent authority,* the old names are retained here. Callidina constricta, Duj. (14) (Plate XII., Figs. 13a, 136) Dujardin's meagre description would fit equally well a considerable number of those CallidincB which mould the food into pellets, and which are distinguished from one another by characters requiring more careful examination than the Bdelloids usually receive. The commonest of those species which have numerous teeth on the jaws, the corona somewhat less in diameter than the widest part of the head, the discs close together, and the spurs short divergent cones, may be taken as the type of C. constricta. To establish C. constricta, Duj., and C. elegans, Ehr. (15), and to distinguish them from the numerous related species, it would be necessary that both should be re- described by a competent authority. Janson (20) brieflydescribes them, but scarcely with the detail necessary to firmly establish them, neglecting, for example, the form of the upper lip, a character of the utmost importance in all Philodinadse. Janson gives C. constrictaas having fewer teeth than C. elegans (8/8 instead of 10 or 11) and a shorterjaw. There is nothing so difficult as to make certain of the number of teeth in thosepellet-making Callidince which have many teeth. They can be clearly enough seen, but the anterior ones are usually thickest, and the others diminish successively till they cannot be distinguished from the fine striae which are found on the rami of all Bdelloids. Very commonly there are four strong teeth, the fourth (counting from the anterior end) much thinnerthan the first; then there is an abrupt transition to finer teeth which are still thicker than the striae, but merge gradually into them. The Cape Royds Callidina, which I identify as C. constricta (see Plate XII., Fig. 13), is a small animal, about ^-Q inch in length (250 /u). It is not much enlarged in the central trunk, which is faintly plicate and not obviously stippled. The small discs are touching, and the whole diameter of the corona is distinctly less than the widest part of the head. The jaws are long and narrow, and each bears four distinct teeth, diminishing in thickness backwards, succeeded by finer teeth which continue to diminish in thickness to the posterior end of the jaw. The rump is clearly marked offfrom the central trunk, but its two segments are only seen as the animal extends itself in creeping. The foot is short, of three joints, and the spurs are very short, quickly tapering, and widely divergent. Habits. It is a quiet sedate animal, moving steadily and readily feeding. It often swims free, rotating on its long axis. Habitat. In most of the lakes at Cape Royds. Common, but not abundant. It is one ofthe two Bdelloids found in Green Lake. s- In company with C. constricta two different forms of egg have been * Mr. D. Bryce is at present engaged on such a revision. ANTARCTIC ROTIFERA 49 found, which may belongto this species or to C. angularis (Plate XII., Figs. 12c-12c). Each of these eggs was found with the jaws of the contained young so well grown that the numerous teeth could be seen. As there are only the two species known at Cape Royds which have many teeth, it is practically certain that these eggs belongto them, but astheywere never found inthe bodiesoftherotifers it cannot be determined to which each belongs. Callidina angularis, sp. n. (Plate XII., Figs. 12a I2d) Specific characters. Small, yellow, much widest in central trunk strongly ; nodose from the lateral projection ofcertain segments, from the neck to the preanal : trunk strongly plicate, and stippled (except head, neck, andfoot). The headis widest at the cheeks, and the corona is distinctly smaller, and about equalindiameter to the neck. Rump narrower than the fourth central segment, its two segments distinct. Foot short, of three segments. Spurs small, divergent, acuminate and acute. Food moulded into pellets. Jaws narrow, teeth many. General description. Length when feeding about ^^ inch, rather greater when creeping. The diameter of the corona is about -^ inch (50 ju), and of the widest part of the trunk about ^<y inch (100 M The rostrum is short and broad ). and the antenna short. There are from eight to ten teeth in each jaw, and they diminish rapidly in thickness towards the posterior end of the jaw. The anterior edges of the three segments succeeding the neck are strongly produced outward, giving a nodose appearance to the anterior trunk. The mid-trunk is also laterally produced into an angle. The fourth central and preanal segments are also produced at their posterior edges. The trunk has few broad clearly marked folds. The preanal has two folds near the middle line. The three toes are short and obscure. The upper lip is a somewhat triangular area. The central portion forms a pointed arch, or may be rounded or slightly cleft. The collar is very inconspicuous. The voluminous stomach is red or brown or pale yellow. The pellets are very obscure. Habitat. In most of the lakes at Cape Royds. Reproduction. The absence of living young makes it practically certain that the species is oviparous. Associated with it were eggs (already referred to under C. constricta) which could only belong to one ofthese species. Affinities. C. angularisis undoubtedly derived from C. constricta. There are so many points in common that they were for long considered tobe identical. The out- line of a Bdelloid rotifer can vary so much during the different movements thatit was considered inadvisable to put much importance on the angular outline of this species. It was only when the peculiar form was found to be alwaysassociated with a stippled skin that it came to be regarded as distinct from G. constricta. Eggs. As to the eggs of this species, see remarks under C. constricta. BRIT. ANTARCT. EXPED. 1907-9. VOL. I. G 50 JAMES MURRAY Callidina habita, Bryce (4) Variety (Plate XL, Figs. 8a-8e) Description. Large, stout, hyaline or yellowish, much widest in central trunk, which is plicate with broad folds. Length when feeding, up to 570 M, diameter of trunk 125 M and upwards, of corona 95 /u- The corona is much wider than the collar, and that is much wider than the neck. The discs are large and bear central setae. They are separated by a space equal to half the diameter of the disc. The collar is prominent and appears two-lobed in dorsal view. It is continued on to the upper lip as two large rounded lobes which meet in the middle line. The rostrum is stout, and the lamellae appear to be quite separated. The antenna is equal to one-third the diameter of the neck. The jaws are large and have a thickened border, sometimes coloured brown. The teeth are two in each jaw, witha thinner one. The voluminous stomach is of a deep crimson colour, and the walls are filled with larger and smaller globules. The yolk-mass contains eight nuclei. The two segments of the rump are obscurely distinguishable. The foot is four-jointed, but there is often difficulty in making out more than three. The spurs are stout, almost cylindrical, quickly tapering to the acute points, divergent. The first foot-joint has a thickening forming a more or less distinct boss. The egg is elliptical and is produced at each pole into a rounded prominence (Fig. 8d). This variety, which is typical in every other respect, differs conspicuously in" the form of the spurs. Those of the type are broad and very acuminate, the lower edge making an ogee curve. The highly coloured stomach is an important feature, but it cannot be considered of much value. specific Another variety. Rather smaller, the two lobes of the upper lip less distinct, separated only by a small notch. Spurs in form like the type, but smaller, and the curvature of the lower edge less marked. The foot-boss more distinct. Otherwise like the type (Plate XL, Fig. 86). Both forms were fairly common in most of the lakes at Cape Royds. They did not occur in Green Lake. In Blue Lake at a depth offifteen feet. Fam ADINETAD^E ily 'Genus Adineta The genus Adineta, the only one yet described in the family, is a small one. It contains at present some eight recognised species. It is better represented in the Antarctic Region than any of the other genera of Bdelloids. Five species were recognised, of which one (A. grandis) is new to science.