Freshwater Triclads New to the Fauna of New Zealand

Transactions and Proceedings of the Royal Society of New Zealand, Volume 78, 1950, Page 410

Freshwater Triclads New to the Fauna of New Zealand By Frances R. Nurse, Zoology Department. Canterbury University College [Read before the Cantebury Branch, December 13, 1949; recived by the Editor, May 6, 1949.] Introduction and Classification The freshwater planarians of New Zealand have so far not been described. The general anatomy and histology of the Tricladida have been well worked out by European and American workers, but in the systematics of the group there has been a good deal of confusion. The freshwater Triclads are now placed in the group Probursalia (previously Paludicola) and this group has been further subdivided into two families, the Dendrocoelidae and the Planariidae, based on the arrangement of the inner zone of muscles of the pharynx. The species described here belong to the Planariidae Kenk (1930) has revised the classification of the Probursalia and his classification seems to have been adopted generally. He has pointed out that it is unsatisfactory to use external features for generic characteristics and that most reliable classification is based on the arrangement of the reproductive system. The most satisfactory, he finds, for generic distinction, is the nature of the female reproductive system. The arrangement of groups based on the course of the oviducts was first put forward by Meixner (1928) and applied to generic classification by Kenk (1930). Hyman (1931) has arranged the North American Triclads, according to this classification. The position of the entry of the oviducts appears to be the main criterion. The genera fall into two groups: I. Oviducts open separately into the terminal portion of the bursa stalk or unite behind this to an unpaired oviduct, which enters the bursa stalk. Genera: Curtisia Graff 1916. Dugesia Girard 1850 (Euplanaria Hesse 1897). II. Oviducts unite to a single oviduct entering the genital atrium. without clasping the bursa stalk. Genera: Phagocata Leidy 1847 (Fonticola Komarék 1926). Planaria Hallez 1894, Polycelis Ehrenberg 1831, Crenobia Kenk. Following the above arrangement, the four species described in this paper would all fall into Group I, as they all have the oviducts or common oviduct entering the bursa stalk. These species are so different from each other in other respects, such as size, shape, and other features of the reproductive system, that it seems impossible to include them all in the genera which have been described in this group. If the nature of the genital atria and the place of entry of the bursa stalk are considered, there appeared to be two forms in the New Zealand species: (a) Those with a so-called divided atrium (i.e. an atrium masculinum round the penis and a common atrium). The bursa stalk

enters the common atrium which opens at the genital pore. (b) Those with one atrium (undivided) around the penis, the genital atrium. The bursa stalk opens into the atrium which then opens at the genital pore. Members of the first group (a) correspond to the diagnosis given by Kenk (1930) of the genus Euplanaria, later corrected to Dugesia by Hyman (1939). I have therefore placed the large form, with the oviducts entering separately the bursa stalk, into the genus Dugesia. It corresponds in other features, also, to descriptions by other authors of species belonging to this genus, e.g. in its large size and possession of definite auricles. Group (b) contains the smaller forms, and these appear to fall into two sub-groups. Sub-group (1) corresponds to the diagnosis for the genus Curtisia proposed by Kenk and adopted by Hyman, in which the “oviducts join to form a common duct which enters the bursa stalk.” This genus, following the descriptions of Kenk and Hyman of North American Triclads, includes the forms with a blunt anterior end, no definite auricles, but with the region of the auricles marked with an oblique white dash. The New Zealand forms corresponding to this can be placed in this genus. Sub-group (2) contains small slender forms with a truncated head and with the oviducts running separately into the base of the bursa stalk. They resemble the North American forms with truncated head, in size, shape, structure of the penis and extent of the testes. The American forms are placed in the genus Phagocata, the diagnostic character of which (oviducts unite to a common oviduct which enters the genital atrium) would exclude the New Zealand forms. A new genus must be created, viz. Spathula. Genus Spathula Diagnosis. Planariidae in which there is one atrium (undivided) around the penis, into which opens the bursa stalk; oviducts continue posteriorly beyond the genital region and a duct from each runs into the basal portion of the bursa stalk; testes numerous; head truncated. Type: S. limicola. In S. fontinalis (Pl. 48, Figs. 1, 2, and 3), the atrium is slightly divided. This is considered to be secondary, brought about by the accommodation of the unusually large penis leading to an asymmetrical arrangement of the organs. In the above arrangement, it can be seen that the shape of the anterior end of the body and the presence or absence of auricles are distinguishing features. The new material at present considered falls into three well-defined groups as regards external features: 1. Triangular anterior end, well-developed auricles, large forms. Dugesia. 2. Rounded anterior end, oblique white dashes in auricular region. Broad, short form. Curstisia. 3. Truncate anterior end, auricles not well developed. Small, slender form. Spathula.

While Kenk considers external features as rather unsafe and not satisfactory characteristics for diagnosis, it has been noticed that in his re-arrangement of the genera (Kenk, 1930), followed by Hyman (1931), and again later in the arrangement of the Triclads of Michigan (Kenk, 1944), the arrangement into genera corresponds closely to the nature and shape of the anterior end. Methods The animals were killed in Steinman's fluid and fixed in Zenker's fluid. The stains used were Mallory's Triple stain, Delafield's Haematoxylin. and Heidenhain's Iron Alum Haematoxylin. Measurements were made on the live animals when they were extended and moving along smoothly. Dugesia montana new species. (Pl. 45, Figs. 1, 2 and 3 and Pl. 46, Figs. 1, 2 and 3.) External Features. Large form up to 25 mm. long and 5 mm. wide, but the most common size of mature specimens is 16 mm. long. The head is triangular with conspicuous auricles which are mobile and constantly moving. The auricles are darkly pigmented at the tips. Eyes, two, slightly anterior to the auricles in oval white patches which lie towards the mid-dorsal line. The colour ranges from pale brown to dark brown and in some cases nearly black, the colour being due to coarse mottling with dark brown pigment on a cream coloured background. The macroscopic pigment pattern varies considerably and there are two varieties which inhabit different regions, distinguished by the pigment pattern. 1. D. montana var. montana: Individuals of this variety possess stripes on either side of the pharynx and genital region, which join posteriorly forming a Y, and stripes lateral to these running nearly the length of the body (Pl. 45, Fig. 1). A few specimens were always found amongst the population, which were without striping and uniformly mottled. The underneath is pale and possesses a few flecks of pigment. Breeding takes place over the summer months. The animals begin to develop their reproductive organs in November. The order of development is similar to descriptions of other freshwater Tricladida. The ovaries and testes appear first, then the organs of the genital region and the genital ducts and finally the vitellarium. Fully mature specimens were found from December to March. The largest number of mature ones was found in late January and February. From March onwards, the reproductive organs disappear and the worms decrease in size, the majority in June and July being 10–11 mm. long. (Based on measurements of 600 specimens, collected from March to November.) 2. D. montana var. albolineata: These possess a clearly defined white line running from the anterior to the posterior end. They may be uniformly mottled (on either side of the white line), or possess stripes on either side of the pharynx and genital region in the form of blocks of pigment (Pl. 45. Fig. 2). In immature specimens the stripe only borders the pharynx. There may also be present deeper pigmentation laterally to the pharynx which, in some, forms definite stripes (Pl. 45, Fig. 3). These three types may be found in a single

population. The underside is pale, with a few flecks of pigment, as in variety montana. Specimens examined in the streams on Banks Peninsula were observed to be mature from November to the end of February, the first cocoons being found in late November and early December. The cocoons are large (2·5 mm. in diameter), unstalked and contain up to 21 embryos. These are unpigmented when they hatch, except for the eyes, which are well marked. Reproductive Organs. The reproductive organs are similar in the two varieties. The testes are numerous, extending from just behind the genital pore. They are mainly dorsal, but some large follicles extend to the ventral side between the gut caeca. The vasa deferentia are ventral and run one into each side of the anterior end of the vesicnla seminalis (Pl. 46, Fig. 1). The vesicula seminalis varies in size according to the stage of maturity. In animals with fully mature sperms it may occupy a large portion of the penis bulb. The vesicula narrows and continues as a slightly convoluted ejaculatory duct which opens on the dorsal side near the tip of the cone-shaped penis. There is a dorsal groove from this opening to the tip. The atrium is divided into a male atrium round the penis and a common atrium which extends from this to open at the genital pore posterior to the tip of the penis. The bursa stalk is narrow dorso-ventrally but wide laterally and enters the common atrium just posterior to the penis tip. The roof of the atrium in this region sometimes possesses a downward projection, the presence or absence of which seems to depend on the amount of muscular contraction during fixation. The ovaries are similar in arrangement to other freshwater Triclads. The oviducts are ventral and turn towards the dorsal side when nearly level with the posterior end of the bursa stalk. They run one into each side of it just before it enters the common atrium. The vitellarium consists of yolk follicles lying between the gut caeca, with vitelline ducts entering the oviducts. Gland cells are situated in the tissue round the genital region and are of two kinds. In the tissue around the bursa stalk are gland cells which produce a fine granular secretion which stains purple with Mallory's triple stain. There are fine ducts from the cells and these open into the basal portion of the bursa stalk. Glands with coarser granules than above lie in the tissue round the common atrium. These stain red to orange with Mallory's triple stain, and fine ducts lead from them into the common atrium. The granules observed in the atrium were more orange in colour than those in the glands. Muscles are well developed round the bursa stalk, but decrease in extent round the bursa copulatrix. Occurrence. D. montana var. montana. Specimens of this variety have been collected from streams in the mountains and foothills of the Southern Alps from 1,200 to 4,000 ft., in Canterbury, Westland, and Southland. The specimens are found under stones in small, stony, mountain streams, fairly fast flowing, mainly on hillsides of beech forest, but sometimes mixed forest. They have not been found in streams in the open at the lower levels, but at 4,000 ft., above the forest-line, they have been found in streams in the open. They have also been found in stony streams running through Schoenus bog. in nil cases there is very little vegetation growing in the streams.

The temperature was measured in the stream throughout the year at Cass, which is 1,800 ft., and was as follows: January 15°C., February 11°C., March 11°C., April 8·5°C., June 5·5°C., August 5·5°C., October 9°C., December 9°C. It was possible to measure only the summer temperatures in other localities, and in the mountainous regions of Southland (Eglinton Valley) at a height of 1,740 ft. the temperature in February was 7·5°C., while lower down the valley at a height of 1,625 ft. it was 11°C. D. montana var. albolineata. This variety is found under stones in small spring streams on hillsides. The streams are usually surrounded by shrubs and trees, and are of a stable type consisting of a series of pools, a soft bottom and large stones, which show no signs of disturbance by flood. They are also found in the headwaters of the larger stony streams into which the smaller streams drain, but they are not so abundant there. Specimens were collected from streams on the hillsides near Patarau, Takaka, hills at the back of Nelson, Marlborough (vicinity of Queen Charlotte Sound), just south of Kaikoura, Banks Peninsula, and Kapiti Island. The temperature in January in these regions ranged from 9°C. to 15°C. They were also collected from Stewart Island and Southland in the area round the Aparima River and Mossburn. Here the temperature in February ranged from 15°C. to 17·5°C. It was 17°C. at Stewart Island. It was not possible to get the winter temperature in these regions. In all of these cases the hills are much lower than those where var. montana is found, are closer to the sea, and the conditions are much warmer. Curtisia stagnalis new species (Pl. 45, Fig. 4 and 4a, Pl. 47, Figs. 1, 2 and 3). External Features. Broad, short form, size up to 12 mm. long and 2 mm. wide. The colour is reddish brown, uniformly finely mottled with very slightly denser mottling on either side of the pharynx. The underside is also pigmented but paler than the upper. The anterior end is rounded, auricles are not present, but there are oblique, pear-shaped white patches in this region which represent the auricular sense organs. There are two eyes, similar in arrangement to D. montana, but the white patches surrounding them are more rounded. Mature specimens and cocoons were found all the year round. The cocoons are stalked and are laid a fortnight after copulation (1–5 cocoons). They take 42 days to hatch at room temperature (10–15°C.). Reproductive Organs. The testes are few in number, from 1–2 on each side, ventrally placed, nearer the mid-line than the ovaries and anterior to the pharynx. The vasa deferentia join posteriorly to form a common duct which enters the penis bulb. There is no enlargement to form a vesicula seminalis. The common duct continues as the ductus ejaculatorius, which opens symmetrically at the tip of the penis. The penis is narrow and finger-like, with weak musculature, but the bulb is highly muscular and projecting slightly into the atrium. There are elongated epithelial cells on the projecting penis bulb. The atrium is undivided. The genital pore opens at the posterior end of the atrium just below the penis tip.

The bursa stalk is a narrow canal dorsal to the penis and expands anteriorly to form the bursa copulatrix which is narrow laterally and wide dorso-ventrally. The bursa stalk enters the dorsal side of the genital atrium. The ovaries have the usual Triclad arrangement. The oviducts are ventral and behind the genital pore they turn dorsally, join to form a wide common oviduct which runs forward and enters the bursa stalk. The vitellarium is scattered in follicles lying between the gut diverticula, both dorsally and ventrally, and extending from just behind the eyes to the posterior end. Gland cells are plentiful in the tissue round the genital region, and as in D. montana they are of two kinds, fine granular with ducts leading into the basal portion of the bursa stalk, and coarser granular with ducts leading into the genital atrium. Occurrence. Curtisia stagnalis has a wide range of habitats. It lives under stones and on the stems of various water plants such as Elodea, water cress, rushes, etc. It is found in ponds (which have a muddy bottom), lakes (both stony and muddy), and rivers of the stable type on the plains. None of these three habitats is subject to rapid changes in the water level and the substratum on which they live is not eroded by floods. It is more abundant in the ponds and lakes than in the streams. Specimens have been collected from pools alongside the Aparima River, Southland, and from Lakes Lyndon, Pearson, Grasmere, Sarah, Raupo, etc., in the Canterbury district; also from streams and ponds in the vicinity of Christchurch. Specimens were also collected from ponds and streams near Blenheim. The temperature ranges from 4°C.–22·5°C. Spathula fontinalis new species (Pl. 45, Figs. 5 and 5a; Pl. 48, Figs. 1, 2, 3 and 4). External Features. Small, slender form, up to 10 mm. long and 1·5 mm. wide. It is brown in colour, mottled, with denser mottling forming a mid-dorsal stripe and stripes on either side of the pharynx which join posteriorly to form a Y. The anterior end is truncated and mobile, forming slight folds along it as the animal moves. There are two eyes, similar in arrangement to the species described above. It is slightly paler in front than the rest of the body. There are very small white patches at the corners of the truncated anterior end, each with a sensory pit leading into a vesicle lined with long cilia. The under-side is pale. Mature specimens were found from September to March. The cocoons are unstalked. Reproductive Organs. The testes are numerous and mainly dorsal, some follicles nearly reaching the ventral side between the gut caeca. They extend posteriorly behind the genital apparatus. There is a vesicula seminalis in the penis bulb, into each side of which run the vasa deferentia. The ductus ejaculatorius is slightly convoluted. The penis has a characteristic shape, somewhat similar to that described by Ullyott (1932) for Planaria vitta. The penis itself is larger than that of P. vitta and lies to the right of the mid-line. The genital pore is only slightly posterior to the penis. The bursa stalk is a narrow canal terminating anteriorly into a bulb-like bursa copulatrix which is separated from the pharynx by

a gut caecum, unlike D. montana, where it is adjacent to the pharynx. The bursa stalk lies to the left of the penis and turns slightly to the right where it joins the genital atrium. There is a well-developed sphincter muscle round the bursa stalk. The ovaries have the usual Triclad arrangement. The oviducts run the whole length of the body, from the ovary to behind the genital region and receive the vitelline ducts throughout. A small duct runs from each into the sides of the base of the bursa stalk. The yolk follicles are extensive. Gland cells are present in the tissue round the genital organs, with ducts running into the bursa stalk. Occurrence. Found abundantly in small streams from springs which have a soft bottom, few stones and a good growth of water cress, etc. They are also found in the larger streams into which the small ones drain, but are not so abundant there. Specimens have been collected from streams on the Canterbury Plains extending into the foothills as far as Avoca, and also from the Cheviot region. In all cases the streams were in fairly flat country, sometimes through swampy areas. Spathula limicola new species (Pl. 45, Figs. 6 and 6a; Pl. 49, Figs. 1, 2, 3 and 4). External Features. Small, slender form up to 8 mm. long and 1 mm. wide. The colour is dark brown, almost black, but slightly paler at the anterior end. The under-side is dark. The anterior end is truncated and similar in shape to S. fontinalis. Reproductive Organs. The testes are numerous, extending from just behind the ovaries nearly to the posterior end. The follicles are mainly ventral, but some large ones reach nearly to the dorsal side between the gut caeca. The penis bulb is fairly large and muscular and the penis papilla is similar in shape to that of S. fontinalis. The vasa deferentia turn dorsally in the region of the penis bulb, unite to form a narrow vesicula seminalis which runs antero-ventrally and then turns posteriorly to continue as the ductus ejaculatorius in the penis papilla. The bursa stalk is median in position and opens into the dorsal side of the genital atrium, the atrium being undivided. Anteriorly the bursa stalk continues into a large symmetrical bursa copulatrix having a posterior bulge on the left side. The corresponding space on the right side is occupied by a testis follicle. The bursa copulatrix is adjacent to the pharynx. The genital pore opens slightly forward of the penis tip. The yolk follicles (vitellarium) lie to the sides, outside the region of the testes. The oviducts continue posteriorly beyond the genital region, and a duct runs from each of them into each side of the bursa stalk as in S. fontinalis. Gland cells are situated in the tissue round about the genital region, with fine ducts leading into the base of the bursa stalk. The bursa stalk is surrounded by muscles as in D. montana. Occurrence. Found in small, stable streams in hilly country, which run across flat, slightly swampy ground. The streams have a muddy bottom, a few stones, but no aquatic plants such as water cress, etc. The temperature ranges from 2°C. to 24·5°C. Specimens have been

Fig. 1—Dugesia montana var. montana. Fig. 2—D. montana var. albolineata. Fig. 3—D. montana var. albolineata. Fig. 4 and 4a—Curtisia stagnalis. Fig. 5 and 5a—Spathula fontinalis. Fig. 6 and 6a—S. limicola.

Fig. 1—Longitudinal sagittal section through the genital region of D. montana. Fig. 2—T.S. through genital region of D. montana showing the dorsal groove in the penis. Fig. 3—T.S. through genital region posterior to Fig. 2, showing the entry of the oviducts.

Fig. 1—Longitudinal sagittal section through the genital region of C. stagnalis. Fig. 2—T.S. of genital region of C. stagnalis showing penis bulb, penis, and genital atrium. Fig. 3—T.S. of genital region of C. stagnalis showing the junction of the common oviduct with the bursa stalk.

Fig. 1—Longitudinal sagittal section through the genital region of S. fontinalis. Fig. 2—T.S. S. fontinalis through the region of the bursa stalk and genital atrium. Fig. 3—T.S. S. fontinalis showing the entry of the left oviduct. Fig. 4—T.S. S. fontinalis showing the entry of the right oviduct.

Fig. 1—Longitudinal sagittal section through the genital region of S. limicola. Fig. 2—T.S. S. limicola showing the entry of the vasa deferentia. Fig. 3—T.S. S. limicola slightly posterior to Fig. 2. Fig. 4—T.S. S. limicola showing the entry of the oviducts. Figures in Plates 45–49 from camera lucida drawings.

collected from the Cass region and the Lindis Pass. Summary 1. One new genus and five new species of Planariidae have been described. 2. Some problems of the classification have been briefly discussed. 3. The habitat of each species has been described. The writer is indebted to the University Grants Committee for the grant which enabled the collecting of material for this work. List of References Goldsmith, 1942. Sexuality in Dugesia tigrina Syn. Planaria maculata. Nature, Lond., 150, 351. Hyman, Libbie H., 1925. The Reproductive System and Other Characters of Planaria dorotocephala. Trans. Am. Micr. Soc., vol. 44, pp. 51–89. — 1931. Studies on the Morphology, Taxonomy, and Distribution of North American Triclad Turbellaria. III, On Polycelis coronata (Girard). IV, Recent European Revisions of the Triclads and Their Application to American Forms. Trans. Am. Micr. Soc., vol. 50, pp. 121–135 and 316–333. — 1937. Studies on the Morphology, Taxonomy and Distribution of North American Trielad Turbellaria. VII, The Two Species Confused Under the Name Phagocata gracilis, the Validity of the Generic Name Phagocata Leidy, 1847. and the Priority over Fonticola Komarck, 1926. Trans. Am. Micr. Soc., vol. 56, pp. 288–310. — 1939. Studies on the Morphology, Taxonomy, and Distribution of North American Triclad Turbellaria. IX. The Priority of Dugesia Girard, 1850, over Euplanaria Hesse, 1817, with Notes on American Species of Dugesia. N. Additional Species of Cave Planarians. Trans. Am. Micr. Soc., vol. 58, pp. 264–275 and 276–284. — 1945. Studies on the Morphology, Taxonomy, and Distribution of North American Triclad Turbellaria, XI. New Chiefly Cavernicolous Planarians. Am. Mid. Nat., vol. 34, pp. 425–484. Kenk, Roman, 1930. a and b. Beitrage zum system des Probursalier (Tricladida paludicola), Zool. Anz., vol. 89, pp. 145–162 and 289–302. — 1941. A Freshwater Triclad from Puerto-Rica, Dugesia antillana. Occasional Papers of Mus. Zool. Univ. Michigan, no. 346. — 1944. The Freshwater Triclads of Michigan. Misc. Publ. Zool. Univ. Michigan, no. 60. Marcus, Ernesto, 1946. Sobre Turbellaria Brasileiros. Zoologia, no. 11, pp. 5–254. Meixner, J., 1928. Der genitalapparat der Tricladen. Zeitsch f. Morph. f. Oekol. d. Tiere 11, 570. Ullyott, P., and Beauchamp, R. S. A., 1931. Mechanism for the Prevention of Self-fertilisation in Some Species of Freshwater Triclads. Q.J.M.S., vol. 74, pt. III, pp. 477–490. Ullyott, P., 1932. Notes on Planaria vitta. Q.J.M.S., vol. 75, pt. III, pp. 483–494. Wilhelmi, J., 1909. “Tricladen.” Fauna and Flora des Golfes von Neapel, etc., Bd. 32. Woodworth, W. W., 1891. Contributions to the Morphology of Turbellaria. Bull. Mus. Comp. Zool., vol. 21, p. 1. Graff, L. von, 1912–17. Turbellaria. Broun's Klassen and Ordnungen des Tierreichs, 4. Akteisburg, Te. Abbreviations for Plates 45–49 b.c., bursa copulatrix; b.s., bursa stalk; c.a., common atrium; d.ej., ductus ejaculatorius; d.g., dorsal groove; g., gland cells; g.atr., genital atrium; g.c., gut caccum; g.p., genital pore; m., month; m.a., male atrinm; musc., muscles round bursa stalk; ovd., oviduct; p., penis; p.b., penis bulb; ph., pharynx; v.d., vas deferens; v.s., vesicula seminalis; y.fol., yolk follicle.