The Classification and Reproductive Organs of New Zealand Land Planarians.
Geoplana moseleyi Hutton, Artioposthia exulans (Dendy) and A. Artioposthia subquadrangulata (Dendy).
By Marion L. Fyfe, M.Sc.,
Department of Zoology, University of Otago.
[Read before Otago Branch, May 7, 1946; received by the Editor, May 14, 1946; issued separately, September, 1946.]
Geoplana moseleyi Hutton.
1895. Geoplana graffii Dendy. Trans. N.Z. Inst., vol 27, p. 180.
1896. Geoplana, graffii var. somersii Dendy, Trans. N.Z. Inst., vol. 28, pp. 212–213.
1901. Geoplana graffii var. clintonis Dendy, Trans. N.Z. Inst., vol. 33, p. 228.
Geoplana graffii var. dorsomarmorata Dendy. Ibid.
In a previous paper (1944) the writer suggested that Geoplana graffii Dendy and G. moseleyi Hutton (1880) were possibly the same, but that no definite statement could be made until the internal structure of G. moseleyi had been examined. Since then the writer has received from Dendy's collection in the British Museum a specimen labelled G. moseleyi and originally identified and named as such by Dendy. On examination in serial section it proved to be anatomically identical with G. graffii. Since G. moseleyi is the earlier name, G. graffii. now becomes a synonym of G. moseleyi.
The writer has also examined in serial sections the varieties of G. graffii, clintonis, somersii and dorsomarmorata which were loaned from the British Museum, and has been able to confirm the previous tentative inclusion of these (1944) in G. moseleyi previously G. graffii. These are therefore now synonyms of G. moseleyi.
Artioposthia exulans (Dendy). Fig. 1.
1901. Geoplana exulans Dendy, Trans. N.Z. Inst., vol. 33, pp. 233–234.
Material. Three preserved specimens from Dendy's collection in the British Museum. Longitudinal sagittal sections were cut in series and stained variously.
Localities. According to Dendy, the planarian is common in the Chatham Islands and is widely distributed in and under rotten logs in various parts of New Zealand.
Type. Dendy did not designate a type specimen, but based his species on a series of syntypes. This is not altogether satisfactory, as in some cases the specimens have been found to be immature, while in others the internal anatomy has shown that two distinct species have been included in one series of syntypes. I therefore designate a lectotype from the series of syntypes based upon the internal anatomy, and select for that a series of sections which show the internal anatomy characteristic of the species. The lectotype consists of eight slides deposited in the British Museum (Natural History), London.
External Characters. Dendy described this planarian as being long and narrow, reaching a length of 45 mm. when fully extended. An average preserved specimen measured 26 mm. with the genital pore 9 mm. and the mouth 13 mm. from the posterior end. The eyes are numerous and arranged round the anterior end, extending to about halfway along the sides.
As only preserved material was available to the writer, Dendy's description of the dorsal and ventral surfaces is given. “The ground-colour of the dorsal surface in life is dirty-white. There is a broad, well-defined median longitudinal band of dark chocolate-brown occupying about one-fifth of the total width of the dorsal surface. On each side of this median band are a number of irregular, more or less discontinuous and anastomosing, narrow, wavy, longitudinal stripes of the same dark chocolate-brown colour. This fine longitudinal striation extends to the margin of the dorsal surface on either side. In addition to the dark stripes, numerous minute specks of the same colour occur, chiefly in the ground-colour on each side of the mid-dorsal band.
“The ground-colour of the ventral surface in life is dirty-white, with two broad longitudinal bands of chocolate (paler than that of the dorsal surface) dividing the ground-colour into three narrow stripes, one median and one submarginal on each side. A few minute specks of chocolate-brown occur sparsely scattered in these bands of ground-colour. Anterior extremity in life pinkish.”
Reproductive Organs. The genital pore (g.p.) leads into a small common genital atrium into which opens the male atrium into anteriorly and the female atrium (f.at.) posteriorly, the two being separated by a large muscular flap. There are two male adenodactyli (aden.), but none in the female atrium. Each adenodactylus is a compact muscular organ enclosing a glandular reservoir (re.) with a narrow winding duct (d.) leading to the atrium. The reservoir here has a characteristic crescentic shape and is quite distinct from the duct. The duct is surrounded by a wide band of circular muscles so that its contraction is independent of the general muscular action of the adenodactylus.
The testes are scattered between the gut branches for almost the whole length of the worm. The two vasa deferentia swell to form very large twisted false seminal vesicles (v.s.f.) which narrow suddenly to form a very small muscular seminal duct (d.s.) opening into the male atrium between the two adenodactyli. As is often found in those forms having adenodactyli there is no penis and it is probable that the very muscular male adenodactyli by pressing on the seminal duct opening between them control the flow of spermatozoa into the atrium. Large prostate glands (pr.) surround the false seminal vesicles and open into the seminal duct.
The paired ovaries lie halfway between the mouth and the anterior end, the oviducts (od.) passing back to join and form the glandular canal (g.c). This opens dorsally into a wide irregular glandular extension of the female atrium and could be regarded as a bursa copulatrix (b.c.) in which fertilization takes place, and where
the shell is secreted round the yolk and eggs before they are forced out of the genital pore.
Remarks. A. exulans differs from the other members of this genus in having only two adenodactyli, both of which are in the male atrium, one on each side of the opening of the seminal duct. The pattern of the markings on the dorsal surface is unusual and characteristic of this species, although the colour may vary from light terracotta-red to grass green.
From the description of the external characters and the arrangement of the reproductive organs it is very probable that A. civis Cardale (1941) is A. exulans, but unfortunately Cardale gives no dimensions of the worm, and as his material is not available no definite statement can be made.
Artioposthia subquadrangulata (Dendy). Fig. 2.
1895. Geoplana subquadrangulata Dendy, Trans. N.Z. Inst., vol. 27, pp. 187–188.
Material. Selected specimens from Dendy's collection in the British Museum. Specimens 447 and 483 in the Department of Zoology, University of Otago.
Localities. Many specimens were collected by Dendy near Christchurch and at Ashburton, where the planarian was very common; one of his specimens came from Dunedin and one from Bluff. Specimen 477 was collected by the writer at Woodhaugh, Dunedin, and 483 at Long Beach, near Dunedin.
Type. Dendy left a great many syntypes from which typical worms were selected for cutting in serial section. From these I have selected the series showing the most characteristic internal anatomy. This series (19 slides) I designate as lectotype, and it will be deposited in the British Museum (Nat. Hist.).
External Characters. The average length of the worm when crawling is 22 mm. The dorsal surface is cream to warm brown with dark brown speckles which are intensified to form three dark brown stripes, one very narrow median stripe and two much broader lateral bands. The ventral surface is pale brown with fine tan speckles, but is not so dark as the dorsal surface. Dendy makes a great feature of the shape of this worm, which he says is quadrangular in section when at rest, though he states that when crawling the worm is long and narrow, the cross-section then being oval. The writer has not noticed anything unusual in the shape of the worm, and there can be no real significance in the shape when it varies according to the amount of movement of the animal.
The eyes are small and are arranged in a horseshoe round the anterior tip. The mouth is about two-thirds of the length from the anterior end and the genital pore is much nearer the mouth than the posterior end.
Reproductive Organs. The genital pore leads into a common atrium separated into male and female parts by one very large adenodactylus (aden.) which lies opposite the genital pore, through which it can project nearly as far as the posterior end of the worm. In the male atrium (m.at.) there is one adenodactylus and in the female atrium (f.at.) there are two, making altogether four adenodactyli,
all of which are attachead to the dorsal wall of the atrium. The adenodactyli are as usual very muscular and extensible, so that it is probable that in the living worm any of the four can extend beyond the genital pore, but in all the worms sectioned (6) one special adenodactylus (the second from the anterior end) was enlarged and projected into or through the genital pore. Inside the adenodactylus the glandular reservoir (re.) is not sharply marked off from the duct (d) as in exulans, the two parts having approximately the same diameter. Surrounding the reservoir is a wide band of gland cells, the secretion of which fills the reservoir. The duct is lined with gland cells separated by a layer of connective tissue from a broad band of circular muscles running round the duct. At the free end the outer muscular layer of the adenodactylus turns in to form a conspicuous cup-shaped sucker (s.) into which the duct opens.
The paired ovaries lie in the usual ventral anterior position about one-third of the distance from the anterior end to the mouth. The oviducts (od.) pass back and join to form a single glandular canal (g.c.) which opens into the female atrium near the ventral surface.
The numerous testes lie between the branches of the gut, the majority in a ventral position, although the ripe testes may extend to the dorsal surface. The vas deferens of each side enlarges to form a false seminal vesicle (v.s.f.) which turns towards the dorsal surface where the vesicles join to form a short narrow seminal duct (d s.) leading to a true seminal vesicle (v.s.) surrounded by its own basket-work of muscles. This vesicle is in two parts, a proximal glandular vesicle (v.g.) lined with gland cells and surrounded by a glandular region, and a larger distal vesicle lined with long goblet cells and with no glandular region round it. The glandular vesicle is usually filled with secretion which stains differently from the secretion of the adenodactylus. A short ejaculatory duct (d.ej.) opens into the male atrium.
The whole genital complex is very muscular and may be dissected out as a complete cylindrical muscular body.
Remarks. Externally this species is similar to A. howesii in size and in stripings, but it is much darker on account of the dark mottling of the ground surface which is pale yellow and unspeckled in howesii. The genital pore is much nearer the mouth than the posterior end in subquadrangudata while in howesii it is about halfway between the mouth and the posterior end. Internally subquadrangulata has four adenodactyli while howesii has three.
Hutton, F. W., 1880. Additions to the List of New Zealand Worms, Trans. N.Z. Inst., vol. 12, p. 277.
Fig. 1.—Diagrammatic longitudinal sagittal section of A. exulans.
Fig. 2. Diagrammatic longitudinal sagittal section of A. subquadrangulata. aden., adenodactylus, b.c., buisa copulatrix: d., duct of adenodactylus; d.ej., ejaculatory duct; d.s., seminal duct; f.at., female at [ unclear: ] ium: g.c. glandular canal; g.p., genital pore; m., mouth; m.at, male atrium, od., oviduct; pr., prostate gland; ie., reservoir of adenodactylus; s., sucker; v.g., glandular vesicle; v.s., true seminal vesicle; v.s.t., false seminal vesicle.