A new and primitive retrobursal planarian from Australian
fresh waters (Platyhelminthes, Turbellaria, Tricladida)
by
Ian R. Ball
Institute of Taxonomie Zoology, University of Amsterdam, The Netherlands
Abstract 1913) and fixed in 70% ethanol. For anatomical
A freshwater Eviella et embedded in primitive planarian, hynesae gen. observations, selected specimens were described from characterized its sp. nov. is Australia. It is by in the usual and sectioned at paraffin way serially of and of branched lack eyes pigment, possession caudally 8 m intervals. The sections were mounted on and fused bursa fi oviducts, fully testes. Although a primary
is its function taken the modified female absent, being over by 75 X 50 mm glass slides, the first section on each canal, the female is posterior to the genital copulatory system slide in the left-hand when the being upper corner male system. Despite this maricolan feature, and other slide label is to the Frontal sections were similarities with primitive southern hemisphere freshwater right. planarians that have been classified in the Maricola, the arranged with the ribbons running horizontally;
present species is placed in the family Dugesiidae of the the sagittal and transverse sections were arranged Paludicola. Evidence from its that it sensory organs suggests with the ribbons vertical. The sections were stained belongs on the main evolutionary line from which the
majority of Australasian freshwater planarians have been with Mallory-Heidenhain stain, or with Phospho- derived. in tungstic Acid Haematoxylin, and were mounted
DPX. variations in these noted Any procedure are INTRODUCTION at the appropriate place in the text.
Among a collection of aquatic planarians from
Australia made by Professor H. B. N. Hynes, and SYSTEMATIC SECTION
Professor W. D. Williams, and described in an Family DUGESIIDAE Ball, 1974a earlier series of publications (Ball, 1974b, 1974c,
of Eviella 1977), there occurred a sample unpigmented gen. nov. and blind specimens from the gravel bed of the Unpigmented Dugesiidae, without eyes, with one River in the State of Victoria. These Howqua of anterior Female pair sensory pits. copulatory hitherto undescribed specimens, representing a to the male organs posterior copulatory organs. showed of species, a number especially primitive Oviducts enter the female genital duct (bursal
features that made their study particularly inter- from canal) separately the sides, and each has a
esting and difficult. In the a new present paper caudal branch. Vasa deferentia enter the penis
is to contain the to be erected new species from the genus bulb separately sides. Testes fused, pre- and and described, a detailed anatomical account, dominantly ventral, and throughout the body of the material is systematic discussion, given. With Cocoon unknown. length. one gonopore.
Type species: Eviella hynesae sp. nov. MATERIALS AND METHODS
Details the and locations The is named for Dr. Eveline Marcus of Säo concerning source present genus
the Paulo in of her of the specimens are given under appropriate recognition major contributions to
species heading below. The specimens were killed invertebrate zoology, and as a mark of my personal
in Steinmann's fluid (Steinmann & Bresslau, gratitude and affection.
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Eviella of 100 the hynesae sp. nov. Alimentary system: For a body length
root of the is about 45 and its — at at Type material. Department of Entomology and Inverte- pharynx tip brate Royal Museum, Toronto, Canada. 66. the is the Zoology, Ontario Thus pharynx about one fifth of
Holotype: sagittal sections on five slides (ROM C94a). Para- body length and is inserted a little less than half- slides frontal types: sagittal sections on three (ROM C94b), the of way down The histological structure sections on four slides (ROM C94c), transverse sections on body. made the is the of five slides (ROM C94d; an error was in mounting pharynx basically same as that the these sections, but the correct order has been marked on each marine and lower freshwater planarians (Kenk, slide), several entire specimens in alcohol (KOM C94). the inner been retained collection. 1930; Ball, viz., musculature Further paratypes have in my private 1974a) consists of distinct circular and longitudinal fibrous
Description. — General features (fig. 1): Maxi- zones. The anterior ramus of the intestine ends size of animals 6 To- mum preserved X 2.2 mm. small diverticula situated blindly as a group of tally devoid of pigment; without Body broad eyes. anteriorly to the brain; otherwise there are no flat with and leaf-like, at the margins but a of this A very noteworthy peculiarities system. com- rounded cross-section The head or medially. munication and the plump between the intestine repro- is with in rounded, a slight point or projection ductive system is not present. the mid-line, and without definite auricles. Just behind the anterior there are two margin deep Body wall (fig. 3): In its general structure the
ciliated one on each side. In life it is pits, probable body wall is similar to that described for other that this species is most similar to Opisthobursa Australasian planarians (Weiss, 1910; Ball, mexicana as figured by Mitchell & Kawakatsu 1974b, 1974c). Eosinophilic gland cells, discharg- 3, (1972: % 1). the ing through epidermis, are very prominent
the flattened anterior and just beneath margin are
distributed in two longitudinal zones far distant
from the lateral margins, there being one strip
such cells of on each side of the mid-line.Marginal
adhesive zones are common in aquatic planarians
but such is (Hyman, 1951) a medial position
unusual.
Sense organs (fig. 1): Although eyes are lacking,
there remain two of in this types sensory organs
the and the species, ciliated pits, sensory fossae.
The ciliated pits are broad and deep invaginations
of the body wall, one on each side (fig. 1) on the
slightly projecting lateral margins of the head.
Their tall nucleate epithelium is free of rhabdites
and clothed in long cilia. Histologically they are
identical with those described for other Austral-
asian planarians (Weiss, 1910; Ball, 1974b,
The fossae of 1974c, 1977). sensory are especial
interest because all hitherto described freshwater
planarians from Australia possess these structures.
In the present species there are two shallow sen-
fossae each side of the anterior sory on margin between the ciliated pits and the mid-line. They
are identical to those described in many species
of the genus Spathula, the most diverse in et genus Fig. 1. Eviella hynesae gen. sp. nov. External features the from Australasian region (Ball, 1977). drawn a preserved specimen.
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2. Eviella reconstruction of the viewed from the Fig. hynesae gen. et sp. nov., holotype. Sagittal copulatory apparatus right
= = = = side, bc = “bursa = male od shell copulatrix”; eg cement glands; ma atrium; right oviduct; pe penis; sg
= deferens. glands; vd right vas
Male reproductive system (figs. 2-3): The testes papilla that projects into the male atrium. In the
swol- of this species are unusual. Normal follicular testes pharyngeal region the vasa deferentia become
of and are absent, instead there is a ramified system len immediately anterior to the copulatory
with that ascend almost fused testes, packed sperm, extend apparatus they vertically before throughout the expanded part of the body, com- bending ventrad to enter the penis bulb separately
the from the there mencing just behind the ovaries. Although sides; is no common vas deferens.
in the the testes are predominantly ventral position (fig. Within bulb, vasa deferentia open into a
3) they frequently extend between and around the spacious seminal vesicle that narrows to form an intestinal branches. The boundary of the male ejaculatory duct opening at the tip of the papilla. gonads within the mesenchyme is often difficult to Together the seminal vesicle and the ejaculatory delimitand spermatogonia, spermatids, and mature duct have the form of a conical flask with slightly
walls that in section the seminal sperm seem frequently to be indiscriminantly scat- concave so sagittal tered the vesicle has in the throughout the body, sperm forming long a peculiar triangular form, as sinuous strands (fig. 3, te). recently described Opisthobursa josephinae (Be-
is All the of the male The male atrium a large cavity, opening ven- nazzi, 1976). epithelia copula-
is and all nucleate trally by a single gonoporewhich surrounded by tory organ are fairly tall, are
The walls the atrium cement glands. of are formed (fig. 3A). from bounded circular a tall nucleate epithelium by and longitudinal muscle fibres. The penis consists Female reproductive system (figs. 2-3): The
conical ovaries of a muscular hemispherical bulb and a paired are ventrally situated, medially to
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Eviella section the X section the Fig. 3. hynesae gen. et sp. nov. A, sagittal through penis, 130; B, sagittal through
C, 130. br = = ov = sm = “bursa”, X 130; sagittal section through the ovary, X brain; in intestine; ovary; sperm
= in the te = vitelline cells to the For further with 2. mass “bursa”; testis; vc adpressed ovary. interpretation compare fig.
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the brain. The with and the lateral nerve cords, just behind 3-4 m wide fixed boulders and rocks,
oviducts arise from the anterodorsal side of each some gravel. It flows fairly swiftly in the flatter
and thus ascend before of the between and it is ovary vertically curving part valley deep slopes,
ventrad and caudad towards the surrounded and overshadowed tall forest. This copulatory appa- by
ratus. Each oviduct enters separately the wall of is the type locality, and the only known locality,
the expanded female genital duct (bursal canal), for this species. The specimens were collected on
hind- 26 Professor and also dispatches a caudal branch to the January 1972 by H. B. N. Hynes.
the oviducts most vitellaria (fig. 2). Usually are
asymmetric in that the part entering the bursal Etymology. — The species is named for Mary E.
canal be much and much on who deserves some credit for the valuable may longer, higher, Hynes
one side than on the other ( fig. 2 ). collections of planarians that resulted from her,
A typical bursa copulatrix is not present. Instead and her husband's, expedition to Australia.
the bursal canal, recognizable from its low nucleate DISCUSSION and ciliated epithelium, overlain by circular and
is In longitudinal muscles, greatly expanded so as to recent years a number of retrobursal planarians
form At its ental end the wall have been described from freshwater habitats. a sperm receptacle. of this is modified Rhodax evelinae described freshwater sperm receptacle (fig. 3B). was as a
Here the epithelium is unciliated and comprises planarian from epigeal waters in Brasil (Marcus,
tall cells. muscula- and has been the very or papillose The outlying 1946) tentatively assigned to
from ture is greatly thickened and consists of inter- family Dugesiidae (Ball, 1974a). And caves
muscle fibres of orientation. The in Mexico there have been described mingled no one two species
whole complex is pierced by eosinophilic unicellu- of Opisthobursa, O. mexicana and O. josephinae
lar This Benazzi glands. region appears to serve as an (see & Giannini, 1973; Benazzi, 1976), attachment for that the former been described zone pyriform sperm masses having independently
in all the examined Kawakatsu These were seen specimens (fig. 3B). by Mitchell & (1972). species
These have been considered marine relicts and there- masses were not bounded by a wall or mem- as brane of kind and thus considered fore have been classified within the Maricola any are not by
to be true The their authors. spermatophores. sperm receptacle, original
which is behind, and sometimes slightly lateral to, The relationships of these forms have been dis-
the male atrium into the above the cussed Mitchell Kawakatsu opens latter just at length by & (1972:
and in this receives the who concluded that whereas Rhodax evelinae gonopore, narrow region 13)
shell and mexicana each opening of numerous glands (fig. 2). Opisthobursa appear to be
The vitellaria are diffuse follicles scattered others closest relatives, and Rhodax should be ac-
throughout the body, usually dorsally, from in corded familial status, they could not be classified
the ovaries almost the tail of the animal. in the front of to together same family because Rhodax eve-
A of vitellaria is linae ductus rather compact group darkly-staining possesses a genito-intestinalis
each the oviduct than bursal Nonethe- usually adpressed to ovary, near an exteriorly opening pore.
and these be the both marine openings, may comparable to less, they regarded as relicts, presum-
parovaria of higher planarians (Woodworth, ably derived independently from the same or dif-
those of 1891), but they are much smaller than ferent marine ancestors.
of would It that Eviella most planariids. Elucidation their status seems probable hynesae too, is a require sections of material at various stages of primitive direct descendent of marine ancestors
maturation, but such material is not available and the temptation to unite all of these species into
to is real. Nevertheless such me. a single family very a
family could be defined only on the basis of prim-
Distribution. — Australia, Victoria, Howqua River itive characters, which in a strictly phylogenetic about 50 km E.S.E. of the ski resort town of is inadmissable. It is also true to that the system say
Mansfield (grid ref. 451415). Here the river is species of Opisthobursa have been assigned to the
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the Fretter Maricola on basis of primitive features and (see & Graham, 1962, fig. 192).
additional evidence of their maricolan nature is In the mollusc, however, there is definitely a
desirable. sperm-ingesting gland associated with the receptac-
In their the of ulum seminis and the general appearance species Rho- sperm are group-orientated
and Eviella share simi- No these latter dax, Opisthobursa, many before absorption. evidence of
latter in their lack of found in slides of Eviella larities, especially the eyes phenomena has been the
and all traces of pigment. Their general habit is the hynesae. In aquatic triclads it is well known that
have of the basic the stored in the tubae of the same, they pharyngés planarian sperm are usualy
and the oviducts and shell into the and the type, glands open oviducts, immediately behind ovaries,
the canal. There the resemblances bursa receiver bursal joint stop. serves merely as a sperm at copula-
Unusual features of E. that are shared with tion and for the of In hynesae digestion excess sperm. some
evelinae are the fused and the be R. testes, caudally species a spermatophore may deposited. Sperm
branched oviducts which also are shared with a be stored in viable for weeks. may a state many
number of Australasian freshwater of the in E. stored planarians Perhaps sperm hynesae are as
the and attached the wall of the female duct genera Reynoldsonia Spathula (Ball, masses on
There with the main- 1974b, 1977). are fewer features in com- numerous glands serving to aid
mon with the species of Opisthobursa. Both the tenance of its potency or viability.
species of Rhodax and of Opisthobursa differ from The recognition that the "bursa" of this animal,
of dorsal E. hynesae in their possession a divertic- receiving the separate oviducts, is really a greatly
of the bursal canal that the oviducts duct raises ulum receives expanded female genital an interesting
and and of Do the shell glands, in the presence a sperm- question. the expanded diverticula of
in the the intestine bursal canal of evelinae and of the expellant pore bursa, opening to R. Opisthobursa
the in the in R. evelinae and to ventral surface species represent the original female genital canal
The is Opisthobursa species. latter condition paral- from which the terminal primary bursal sac has
leled in marine lost? the a planarian, Oregoniplana opistho- been The loss of primary bursa is com-
pora, from Pacific North America (Holmquist & mon in marine planarians (Ax, 1956) but often
Karling, 1972). In this species the female genital it is later, in evolutionary terms, replaced by a
duct from the atrium and to in the runs posteriad opens secondary bursa, or bursae, as Uteriporidae
the exterior without and for forming a bursal sac. Bdellouridae example (see Holmquist &
Apart from the fully fused testes, the most sin- Karling, 1972; Ball, 1975). It is not impossible
gular feature of the new species relates to the that the "bursae" of both R. evelinae and the
there is what such female genital duct. At first glance Opisthobursa species are secondary acquisi-
and it is that seems to be a large bursa copulatrix posterior to tions, already apparent the histolog-
the That it bursa ical the O. mexicana penis. functions as a copulatrix structure of bursa of is not
is evidenced by the fact that usually it is packed quite like that of other aquatic planarians, and
But it be is in with sperm. by its structure cannot a the peculiar bursal pore not present specimens
primary bursa; the epithelium is low and ciliated not fully matured (Mitchell & Kawakatsu, 1972: and in It clothed strong muscle fibres. seems that 10).
the bursa has been lost and its function The similarities with maricolan forms primary many not-
has been taken over by the greatly expanded bursal withstanding I decline to classify Eviella hynesae
canal (female genital canal). Such is the case also with the marine planarians. It is undoubtedly an
and in Procerodes variabilis and Meixnerides armatus, old primitive form, but its paludicolan nature
two marine from the southern hemi- is evidenced the structure of the anterior planarians by sensory
the fossae and ciliated These sphere (Böhmig, 1902; Westblad, 1952). organs, sensory pits.
The attachment for the of unknown in the peculiar zone sperm are a type quite Maricola and
is without in the all Australasian fresh- masses (fig. 3B) parallel aquatic yet very common in nearly
similar condition planarians but appears to the water planarians (Ball, 1977). Eviella hynesae
found in a mollusc tuber- to the main line that prosobranch cularisCerithiopsis clearly belongs evolutionary
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to 1977. A of the genus has diversified give the majority of the Austral- , monograph Spathula (Platyhel- minthes, Turbellaria, Tricladida). Aust. J. Zool., Suppl. asian forms and therefore it must be classified with Ser., 47: 1-43. them in the It is unfortunate that the Dugesiidae. BENAZZI, M., 1976. Opisthobursa josephinae, a new troglo-
is because I attached bitic Mexico. Accad. naz. new species blind have great planarian from Chiapas, Atti
Lincei, Rendiconti, CI. Sc. fiz. mat. nat., (8) 59: 533- character importance to eye structure as a defining 536, pis. I-II. of the 1974b, but the Dugesiidae (Ball, 1974c), BENAZZI, M. & E. GIANNINI, 1973. A remarkable cave pla-
Sub- secondary evidence is sufficient to warrant its in- narian: Opisthobursa mexicana Benazzi, 1972. In: terranean fauna of Mexico, part II. Further results of clusion in this family. the Italian zoological mission to Mexico, sponsored by
the National Academy of Lincei. Accad. naz. Lincei, ACKNOWLEDGEMENTS Problemi attuali di Scienza e di Cultura (Sez. Missioni
It thank Professor ed — I), 47-54, pis. is a pleasure to H. B. N. Hynes (Waterloo, Esplorazioni Quaderno 171: I-IV.
Canada) for entrusting these valuable specimens to me. BÖHMIG, L., 1902. Turbellarien: Rhabdocoeliden und Tricla-
I also thank Professor C. H. Fernando (Waterloo, Canada) diden. Ergebn. Hamburg. Magalh. Sammelreise, 3: 1-30. and W. D. Williams (Adelaide, Australia) for attempting on FRETTER, V. & A. GRAHAM, 1962. British prosobranch mol-
behalf further material from the luscs: my to recover Howqua i-xvi, 1-755 (Ray Society, London).
material the G. River. The opportunity to study comparative in HOLMQUIST, C. & T. KARLING, 1972. Two new species
United States National Museum was obtained through the of interstitial marine triclads from the North American
trends kindness of Dr. Roman Kenk, and Dr. Eveline Marcus made Pacific Coast, with comments on evolutionary her slides of Brasilian material available to me. For all this and systematics in Tricladida (Turbellaria). Zoologica help I am grateful. The drawings are the work of Maria Scr., 1: 175-184.
Tran Thi Vinh-Hao whose labours I acknowledge with HYMAN, L. H., 1951. The invertebrates, 2. Platyhelminthes gratitude. The entire study was supported by operating grant and Rhynchocoela: i-vii, 1-550 (McGraw-Hill, New
A0016 of the National Research Council of Canada. York) .
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Received: 12 July 1977
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