365

ON THREE NEW SPECIES OF .

By DAVID BRYCE.

(Read Jlla?'ch 26th, 1912.)

PLATE 12. THE description of three new species of Bdelloid Rotifera affords an opportunity of recommending attention to the form of the Upper Lip as one of the most valuable characters which go to make up the individuality of species of the Philodinidae. The earliest mention of this structure which I have found is by Milne (18), who early in 1886 referred to it as the" brow," and very briefly pointed out its different forms in three species then described. Later in the same year Zelinka (20) named it the Upper Lip (" Oberlippe "), and made use of it in his descriptions of two new species; and again, in 1891 (29), gave" the form of the corona and of the upper lip" as the third of eleven characters which should be ascertained as far as circumstances permit and included in the description of any species of the genus Callidina. The upper lip is not possessed by all the Bdelloida, but only by those which constitute the family of the Philodinidae. Although perhaps, strictly speaking, it is not actually a part of the corona, yet it is only visible when the wheel organ is displayed, and it is withdrawn with it within the mouth when the resumes its normal or creeping position. That being the case, it is con­ venient to look upon it as a subsidiary part of the corona, of which in many cases it has become the dominant characteristic (from the point of view of the student). When the ciliated discs on their pedicels have been pushed forth from the widely opened mouth, the upper lip comes to be visible in direct dorsal view as an unciliated surface of the head in front of the reverted rostrum, merging gradually at either side into the "collar," the wider part immediately succeeding the lateral bases of the pedicels. In a few of the tube-dwelling species-Habrotrocha longiceps, H. Leitgebii, etc.-the upper lip has been considerably enlarged so as to become long in proportion to the breadth of the head, 366 DAVID BRYCE ON THREE NEW SPECIES OF CALLIDINA. DAVID BRYCE ON THREE NEW SPECIES OF CALLIDINA. 367 a development which is probably directly. connected with the some species only very slightly marked, as, for instance, in the " domestic" habits of these species. In Plost cases, however, genus and in cit9'ina and some others, but more the upper lip is represented by a shallow area, whose anterior usually there is a quite distinct furrow or notch, and in many margin is subject to astonishing variation. It is therefore the species the lobes are separated by a relatively wide interspace, outline of this anterior margin which is referred to in descrip­ more or less flat. tions of the upper lip. While experience has shown that one To the general rule that Philodinidae with a tube-like lumen must not absolutely rely upon the constancy of this outline, it have a bilobed upper lip, perhaps the best-known exception is has also shown that variation therein is most infrequent among Callidina Eh~'enbe?'gi,whose high upper lip forms a single lobe individuals of one species, whilst there is scarcely any other detail with rounded front, C. nana sp. nov., is likewise an exception, with so wide a range of variation when one species has to be and in other respects shows some appearance of close relationship compared with another. 1;0 C. Eh9·enbe~·gi. To some extent the outline of the anterior margin appears to Another exception is found in C. decm'a sp, nov., which, unlike vai'y according to the proximity to each other of the two pedicels. C, nana, has widely separated pedicels, but the upper lip rises so If these are adnate, as in Hab9'ot9'ocha pusilla and other species slightly as to leave uncovered the nexus between their bases. with very small coronae, Or closely proximate, as in H. constricta, The third new species, C. concinna, conforms strictly to the Callidina Ehrenbergi and others, the upper lip is usually centrally rule indicated, the high upper lip being, I think, quite distinctly, prominent or high, frequently attaining to the level of the discs though not deeply, notched. surmounting the pedicels. When, however, the pedicels are Of these three species, only C. decm'a appears to be uncommon. widely separated, as in the four-toed genera, Philodina and I have found both the others on several occasions. C. concin?w others, the upper lip is usually of moderate height, seldom rising is representative of a series of "races," which agreed in the more than about halfway up the pedicels. On the other hand, characters specified, but varied somewhat in their size and other whether the pedicels are proximate or remote, several species detl1ils insufficiently important to justify their separation. have an upper lip, which is decidedly low, either showing a The figures of the new species were first drawn to a scale slightly convex outline or having a very obtuse median angle. equalling x 800, but have been reduced to the equivalent of x 530. In such cases, when the pedicels are moderately or widely The numbers after names of authors refer to the Bibliography separated, it sometimes happens that the nexus which connects appended to my paper on "A New Classification of the Bdelloid pedicels, usually base, is exposed place of the at their left in Rotifera" (Journ. Q~6ek.Micr. Cl16b,Ser. 2, Vol. XI. p. 61), being hidden. Again, when the pedicels are rather or very widely separated, the upper lip is most usually carried forward Callidina sp. novo (PI. 12, Fig. 2). between the pedicels towards the ventral side. nana

These several forms are complicated by another line of varia­ Specific Cha~'acters.-Coronarather narrower thilll collar; tion, which seems to have deeper significance than the variations pedicels distinct, closely proximate; upper lip rising nearly as of height, and which possibly has no real connection with them. high as discs, narrow, undivided, rounded. Rami with two Whether the upper lip be high or low, it is, with few exceptions, teeth each. Foot short, of three segments; spurs short acute more or less obviously bilobed if the species belong to that section cones, with little or no interspace. Egg with moderately of the Philodinidae in which the lumen of the stomach is tube· numerous short blunt spines. like. If, on the contrary, the species be a pellet-making form, A small and somewhat slender form not uncommon in ground with the usual more bag-like lumen, then the upper lip is, and I mosses, and occasionally met with in Sphagnum. When creeping think without known exception, simple and undivided by the about it has much the appearance of a small Habrotrocha, the faintest furrow or notch. When it is bilobed, the lobes are in head and rostrum being a little more elongate than is usual in 368 DAVID BRYCE ON THREE NEW SPECIES OF CALLIDINA. DAVID BRYCE ON THREE NEW SPECIES OF CALLIDINA. 369

the genus Callidina. When feeding, the resemblance to the interspace. Egg oval, smooth, slightly produced, or with low pellet-making genus is again pronounced, the narrow corona prominence at one or both poles. and the high upper lip being quite of the Habrotrocha type. In the genus Callidina as now restricted, species with a narrow The" interference" effects of the flashing cilia and the position or small corona are few in number. In the course of examining immediately below the upper lip of the inner edges of the barely wall and ground mosses from various localities, I have found separated pedicels made it extremely difficult to define wit.h several series of examples which agreed approximately in the reasonable certainty the true outline of the upper lip, but I above characters. My sketches of these show them as failed on repeated examinations to distinguish any trace of a somewhat dissimilar in their feeding position, but the differences notch on the anterior margin. .After feeding with carmine I seem to arise only from small variations in the relative distance found that the stomach had a very delicate tube-like lumen, of the pedicels, in the position and separation of the spurs, and .within which I could discern particles of pigment circling in the in the size of the rotifer. I cannot find that any of these typical manner. slightly differing forms have been hitherto described, and I have The species seems related to Callidina Eh1'enbergi Janson, which therefore selected the largest, which I have met with on several has the same combination of two-toothed rami, high, undivided occasions, to be the type for a new species. upper lip and spinous eggs; but J anson's species is considerably It is of moderate size, intermediate between C. habita and larger, the corona is proportionately wider, the upper lip is more C. nana, both in length and stoutness. With the exception of broadly rounded in front and the eggs are covered with numerous the head and neck, which are rather less stout than is usual in spines almost crowded together. the genus, the general structure is quite typical. The dorsal In C. nanCbthe egg is of the customary slightly flattened oval antenna is moderately short, about one-third of the neck width. form, but is sparsely covered with blunt spines varying in length I could not definitely see more than three foot joints, but in some from 3 to 6 I-'- according to position, those near the poles being cases I thought there were probably four. It is rather active in longest, those near the centre the shortest. Including the spines its movements when disturbed. the egg sketched measured about 70 I-'- long by 41 p wide. Maximum lengt.h, about 330 ft; in feeding position figured, The animal is generally colourless, or nearly so, the skin more about 285 ft; corona, width 411-'-; collar, 38 ft; neck, 32 I-'-; or less finely stippled. It is restless when first put into a small spurs, 8 p. cell, but after a few days' isolation feeds quietly, and endures Habitat, in ground or wall mosses. confinement rather well. Maximum length, about 220 1-'-;corona, 20 ft wide; collar, 241-'-; Callidina decora sp. novo (PI. 12, Fig. 3). spurs, about 5 ft long. Originally observed in Sphagnum from Epping Forest, later Specific Characte1's.-Of medium size and stoutness. Corona in various ground mosses, intm' alia in Thuidi~wntanubr·iscinum, ample. Upper lip undivided, rising in a low curve, showing high collected for me in St. Leonard's Forest by Mr. A. W. nexus between divergent pedicels, widely separated. Rami with Sheppard. two to three teeth. Spurs short cones with moderate inter­ space. Callidina concinna sp. novo (PI. 12, Fig. 1). Several examples of this moderately large form were obtained from moss growing on rocky outcrops near the top of Ben Specific Chamcte1's,-Corona moderately narrow, scarcely ex­ Vrachie, in Perthshire, in 1907. When creeping about they did ceeding collar, pedicels distinct, approximate or little separated. not show any salient peculiarities, but in the feeding position Upper lip high with median notch. Rami two-toothed. Foot of the unusual form of the upper lip attracted attention. When three joints; spurs short cones, divergent, with small or no feeding, the animals assumed a semi-squatting, rather trim and Journ. Q.M.C. Ser. 2,vol.XI,Pl.l~ 370 DAVID BRYCE ON THREE NEW SPECIES OF CALLIDINA. , " ,distinctive pose, in which the ample width of the corona became accentuated. The widely separated pedicels are distinctly divergent, although of moderate height. The trochal discs converge slightly to the median line, and have also a moderate dorsal inclination. The secondary wreath does not pass round the pedicels at their bases as is usual, but about one-third of their height up, a peculiarity which I think occurs also in Mniobia magna (Plate) and M. 8ca1'latina (Ehr.). The nexus between the pedicels is exposed, and so high as to be nearly level with the inner margin of the trochal discs. Oentrally it is decorated with two minute fleshy ligules. The upper lip rises in ,a very moderate curve nearly to the level of the nexus, and shows no trace of notch. As is not unusual, the post-oral segment is withdrawn within the following one when the animal is feeding, the dorsal antenna only being left visible. The rami appeared to ~1' be, of normal form with the dental formula 2+ A rather wide stomach lumen could be easily defined. The lumbar plicae persisted in the feeding position. The foot structure was not ,satisfactorily determined. My impression was that the toes were absent or modified to a sucker-like disc, in which case the species would properly belong to the genus Mniobia, and this relation­ ship receives some support from the position of the secondary wreath. Pending further examination, it seems hest to leave the 2. species in the genus Oallidina. 3. Maximum length not rec9rded; in feeding position, as figured, about 185 fL; corona, about 63 fL; collar, about 45 fL; spurs, about 5 fL; interspace, 6 fL. Habitat, as stated above.

DESCRIPTION OF PLATE 12. Fig. l. Callidina concinna sp. nov.; a, egg. " 2. Callidina nana sp. noy.; a, egg. " 3. Callidina decQ1'asp. noy.

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D, B,,'Y c e del. ad nat,. A.H. Sea-TIe Ji~h Jov,m, Qi"kett loficro.copical Cl"b, Se1'. 2, Vot. XI., No, 70, Ap,·ilI912. C alii dine." s·pp. noVB!l.