A new and primitive retrobursal from Australian

fresh waters (Platyhelminthes, , 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. that have been classified in the , the arranged with the ribbons running horizontally;

present species is placed in the family 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 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. 150 I. R. BALL - A NEW RETROBURSAL PLANARIAN

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 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 , 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. 47 - BIJDRAGEN TOT DE DIERKUNDE, (2) 1977 151

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 152 I. R. BALL - A NEW RETROBURSAL PLANARIAN

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. BIJDRAGEN TOT DE DIERKUNDE, 47 (2) - 1977 153

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 . 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 154 I. R. BALL - A NEW RETROBURSAL PLANARIAN

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. 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 47 - BIJDRAGEN TOT DE DIERKUNDE, (2) 1977 155

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