Additions to the Rotatoria of New Zealand. Part V.
108 Knowles Street, Christchurch, N.1.
[Read before the Canterbury Branch, June 4, 1952; received by the Editor, June 10,1952.]
The author lists seventeen species of the Rotatoria not previously found in New Zealand, including six marine species, and one new cyclomorphic form of Brachionus calyciflorus. It is suggested that many of the animals which have been given specific rank in the genus Synchaeta may be merely varieties of a few species.
This paper contains a list of seventeen species of the Rotatoria not previously recorded in New Zealand, and includes one new cyclomorphic form, and six marine species. The fresh water forms were nearly all taken from acid water swamps in the mountainous region of the South Island, and the marine forms were collected from the coastal waters of Banks Peninsula.
Four of the marine species are of the genus Synchaeta, which has not been revised since Rousselet's monograph of 1902. The identification of marine forms of the Synchaetidae has proved difficult owing to distinct variations from the type specimens being common, and the presence of what may be intermediate forms. Mr. P. J. Parr found the same complication in 1948 when studying the marine Synchaetidae in Otago waters. Some of these difficulties may be due to the material being preserved, but this will not account for all the differences which have been found. In 1908 Wesenberg-Lund in his “Plankton Investigation of the Danish Lakes “claimed that nearly all the fresh water species of the genus Synchaeta were merely varieties of a very few species. Although Rousselet (1909) and other subsequent workers did not agree with Wesenberg-Lund's conclusions, no serious attempt has apparently been made to prove them incorrect. His theory would explain many of the variations which have been described. Further, since there is little morphological difference between the marine and fresh water forms, his theory, if correct, could be applied to the whole genus. In any case, a complete revision of the genus Synchaeta is necessary before many of the outstanding taxonomic problems can be solved, or varieties assigned to their correct species.
To save space, synonyms have been reduced to a minimum, and in most cases short titles given to the literature cited. This particularly applies to the older references, and full titles and synonomies are given in Harring's “Synopsis of the Rotatoria” Bulletin 81 of the Smithsonian Institute, which is available in all University Colleges throughout the Dominion.
Brachionus calyciflorus Pallas, 1766.
Elench. Zooph, 1766, p. 93.
New Reduced Form. Although cyclomorphic forms are of little taxonomic value they are of interest to limnologists, and others studying the problem of cyclomorphisis. B. calyciflorus is, probably more than any other rotifer, subject
to cyclomorphic changes, as the synonomy of the species shows. This new form would appear to be the most extreme variation in the cycle.
The body, which is shown in outline in Text Fig. 1, is saccate and generally asplanchnid in appearance. The greatest diameter of the animal is at approximately two-thirds of its length, and a transverse section at any point of the body is a circle. The animal has the usual four anterior spines which, however, are small; there are no posterior spines, and the foot sheath is reduced to two small lobes. The adductor and retractor muscles for the head and foot are approximately twice the length of those in the normal animal with posterior spines. The foot and interior organs are normal for the genus. The animal swims in a manner suggestive of the Asplanchnidae, and seldom uses its foot.
The animal was observed for three successive years in Victoria Lake, Christ-church, when it was common at temperatures between 10° and 14° C. and pH ranges of 7.5–8. No intermediates were observed, but at 20° C. the normal form with long anterior and posterior spines appeared. Two parthenogenetic generations of the reduced form were bred in the laboratory, the progeny in each case being identical. The sexual stage was not observed.
Average length of animals, 300 microns; greatest width, 270 microns; anterior spines, 20 microns.
Cephalodella gibba (Ehrenberg).
1832 Furcularia gibba, Ehrenberg. Abh. Akad. Wiss., Berlin, 1832, p. 130. Russell, 1945, p. 105.
Locality. Weedy creek entering Lake Ellesmere, the waters of which are brackish. Temperature 14° C. Not common. Specimens differed from those found in fresh water, and were generally smaller in size. The body was shorter and arched dorsally, with straight toes having the distal ends reduced to sharp points. The ganglion was also smaller. Length of body, 150 microns; dorso-ventral depth, 84 microns; toes, 52 microns.
Cephalodella mucronta Myers, 1924.
Rotifer Fauna Wis. Pt. 2, p. 510.
Locality. Swamps near Lake Sumner, Canterbury Acid water. The only difference from the type description was that the sinus between the dorsal spine and the ventral point of lorica was triangular and not rounded. Length of specimens, 250 microns; toes, 100 microns. Not common.
Dicranophorus dolerus Harring & Myers, 1924.
Rotifer Fauna Wis Pt. 4, p. 707.
Locality. Bealey, Canterbury. In swampy creek. Not common. Temperature, 17° C., pH. 7. Length, 320 microns; toes, 80 microns. The trophi were of normal type except that the unci were straighter than usual.
Keratella crassa Ahlstrom, 1943.
1943 Bull. Amer. Mus. Nat. Hist., vol. lxxx, Art. xii, pp. 433–4.
Locality. Marine, Lyttelton Harbour, Canterbury. Not common. Total length, 160 microns; length of body, 90 microns; W/LO. 71. Anterior spines: med., 24 microns; inter., 13 microns; lat, 15 microns. Posterior spine, 46 microns.
Dorsal plate areolations heavy and no pustulation on either plate. Ahlstrom says that this is a transcursion species being found in acid and alkaline waters, but apparently this is the first time it has been found in a marine habitat.
Lecane hornemanni (Ehrenberg).
1834. Euchlanis hornemanni Ehrenberg. Abh. Akad. Wiss. Berlin, 1834, p. 206. Harring & Myers, Rotifer Fauna Wis. Pt. 3, p. 377.
Locality. Swampy pools near Starvation Gully, West Coast Road, Canterbury. Temperature, 13° C. pH. 5.5. Fairly common. Total length, 130 microns; width of dorsal plate, 96 microns; of ventral plate, 65 microns; toes, 30 microns.
Lindia truncata (Jennings).
1894. Notommata truncata Jennings. Bull. Mich. Fish. Com., p. 16.
Locality. Creek at Bealey, Canterbury. Temperature 17° C. pH. 8. Fairly common. Total length, 190 microns; toes, 10 microns. The specimens differed from the type in the trophi. The fulcrum was shorter in all specimens, with the unci shorter and more robust.
Microcodon clavus, Ehrenberg (1838).
Die Infus., vol. I, p. 118.
Locality. Swampy pools in Lake Sumner District, Canterbury. Normal specimens were found, the only difference from the type description being that the foot was shorter and the claw longer. The ganglion was very large and apparently of a purple colour, but Mr. Kurt Wulfert, of Bad Lauchstadt, has, in a private communication, stated that he has found that it is the epipharynx which is purple, and that the posterior part of the mastax is a bright yellow. Length of body, 127 microns; foot, 20 microns; toe, 37 microns. Diameter of ganglion, 32 microns. Length of rami, 32 microns; of fulcrum, 23 microns. Taken in acid water, but temperature and pH. unknown. Rare.
Monostyla furcata Murray. 1913.
1913. J. R. M. S., p. 355.
Locality. Swampy pools near Starvation Gully, West Coast Road, Canterbury. Temperature, 13° C. pH. 5.5. Fairly common. Also found in swamps in Lake Sumner District, temperature and pH. unknown. Fairly common. Length: total, 94 microns; dorsal plate, 69 microns; ventral plate, 71 microns; toe and claw, 23 microns. Width of dorsal plate, 67 microns; ventral plate, 58 microns.
Monostyla perplexa Ahlstrom. 1938.
1938. Jour. Elisha Mitchell Sci Soc., Vol. 54, No. I, p. 101.
Locality. Acid water swamps near Lake Katrine, Canterbury. Fairly common. Total length, 156 microns; toe and claw, 46 microns. The basal spicules on the claw are rudimentary.
Monostyla tethis Harring and Myers. 1926.
Rotifer Fauna Wis. Pt. 3, pp. 405-6, Pl. XLIII; Figs. 3, 4.
Locality. Swamps near Starvation Gully, West Coast Road, Canterbury. Temperature, 13° C. pH. 5.5. Not common. Typical specimens. Length of
dorsal plate, 69 microns; ventral plate, 76 microns; foot, 23 microns. Width. dorsal margin, 57 microns; ventral margin, 69 microns.
Squatinella mutica (Ehrenberg).
1832. Stephanops muticus Ehrenberg. Abh. Akad. Wiss. Berlin, 1832, p. 138.
Locality. Seepage pools in bed of Waihi River, South Canterbury. Approximate temperature, 18° C. pH. 8.6. Rare. Length: body, 96 microns; foot, 27 microns; claws, 13 microns.
Synchaeta baltica Ehrenberg, 1832.
Abh. Akad. Wiss. Berlin, 1832, p. 135. Rousselet, J. R. M. S., 1902, p. 399.
Locality. Marine. Menzies Bay, Canterbury, and Lyttelton Harbour. Length, 350–530 microns. Common. Specimens examined had an elongated conical body different from the shape shown by Rousselet. The trophi showed differences in the unci which were U-shaped (as shown in Text Fig. 2) with 5–6 lancet-shaped teeth in addition to the stronger tooth. A number of variations were also found, but since the material was preserved these may have been due to the action of the formalin which causes considerable changes in the form of most members of this genus. Specimens from Lyttelton Harbour were in general more bell-shaped than those from Menzies Bay. An attempt will be made later in the year to collect live specimens of the Synchaetidae when the presence of what may be intermediates can be verified.
Synchaeta cecilia Rousselet, 1902.
1902. J. R. M. S., 1902, pp. 406–8.
Locality. Marine. Lyttelton Harbour, Canterbury. (Collected in September.) Not common. Overall length 100–123 microns. A few specimens of similar size were also found in the Menzies Bay material. The teeth on the unci were broader than usual and interlocked when the trophi were closed. In a few cases the usual cleft eyespot was separated into two distinct spots, but this may have been due to the action of the preservative.
Synchaeta fennica Rousselet, 1909.
1909. J. R. M. S., 1909, p. 170.
Locality. Marine. Lyttelton Harbour. (Collected in September.) Not common. Overall length, 220–250 microns. This is a distinctive species even in preserved collections. Rousselet (1909) separates bicornis from fennica on account of the additional frontal spots of the former, and the position and angle of the appendages. The last two characteristics would appear to be of little value, and specimens were examined, undoubtedly fennica, in which the position and angle of the appendages would fit either species. In two cases pigmented granules were found in the anterior median area, not sufficient, however, to be called eyespots. If, however, these were the rudiments of frontal eyespots there would appear to be no real difference between fennica and bicornis.
Synchaeta monopus Plate, 1890.
Weber die Rotatorienfauna des bottnischen Meerbussens. Zeit. Wiss. Zool. Leipzig, Vol. 49, pp. 1–42. Rousselet, J. R. M. S., 1902, pp. 404–6.
Locality. Marine. Menzies Bay, Canterbury. Rare. Overall length 200–220 microns. Width over auricles, 100–112 microns. In addition to normal specimens three were found having short blade shaped toes, and two double frontal eyespots, one on each side of the median line, otherwise they were similar to normal specimens. These may be a new variety of monopus, but until live specimens can be secured it would be unsafe to describe them as such.
[In addition to the above a number of specimens were examined which, owing to their contracted condition, could not be assigned to any species. This must always be the difficulty with preserved material, which is unsuitable for the identification of the Synchaetidae.]
Taprocampa annulosa Gosse. 1851.
Ann. Mag. Nat. Hist. Ser. 2, Vol. 8, p. 199.
Locality. Pools near Starvation Gully, West Coast Road, Canterbury. Temperature 13° C. pH. 5·5. Not common. Total length, 175 microns. Annulations strongly marked.
Trichocerca marina (Daday).
1890. Diurella marina Daday. Ert. Kor., Vol. 19, No. 17, p. 16.
Locality. Marine. Menzies Bay, Canterbury. Not common. Total length, 240 microns. Collected in September.
This paper would not have been possible without the assistance of those who, often at considerable trouble, have made collections for me. These include Mr. H.
Talbot, of Springfield; Mr. W. Dukes, of Christchurch; and Dr. R. Pilgrim, of Canterbury University College. To all of these I tender my thanks.
I am also indebted to Mr. Kurt. Wulfert, of Bad Lauchstadt, Germany, for illustrations and references of some of the cyclomorphic forms of Branchionus calyciflorus, and to Messrs. A. L. Galliford, and C. Rudlin, of England, for valuable information of the Synchaetidae.
Rousselet, C. F., 1902. “The Genus Synchaeta.” J. R. M. S., 1902, pp. 269–80.
— 1909. “Synchaeta fennica.” J. R. M. S., 1909, pp. 170–3
Wesenberg-Lund, C., 1908. “Report of the Plankton Investigation of the Danish Lakes.”