Two new semi-aquatic species of Diplotrema (Oligochaeta: Megascolecidae: Acanthodrilinae), with a re-description of the type species

7 Pages·1998·2.2 MB·English

by  G R Dyne

TWO NEW SEMI-AQUATIC SPECIES OF DIPLOTREMA (OLIGOCHAETA:
MEGASCOLECIDAE: ACANTHODRILINAE), WITH A RE-DESCRIPTION OF
THE TYPE SPECIES
G. R. DYNEAND B.G.M. JAMIESON
Dyne, G.R. & Jamieson, B.G.M. 1998 0629; Twonewsemi-aquaticspeciesofDiplotrema
(Oligochaeta; Megascolecidae: Acanthodrilinae), with a re-description ofthe type species.
Memoirs ofthe QueenslandMuseum 42(2): 487-493. Brisbane. ISSN 0079-8835.
Two new species ofthe genus Diplotrema sharing a suite ofmorphological characters and
a semi-aquatic mode of life are described. Together with the previously described D.
tyagarah. they are placed in a species-group the nominate species ofwhich is the generic
type-species, D. fragilis. The latter taxon, of pivotal importance in early phylogenetic
schemes owing to an erroneous determination of the condition of the male pores, is
redescribed from thesyx\\yxies.nEarthworms, Megascolecidae, Diplotrema, semi-aquatic.
G.R. Dyne, EnvironmentAustralia, PO Box 787, Canberra ACT2600, Australia: B.G.M.
Jamieson, Department ofZoology,University ofQueensland, St Lucia 4072. Australia; 4
May 1997.
The significance ofthe type-species ofDiplo- diverticulum bearing numerous sperm chambers
trema, D.fragilis Spencer, in the inferred phylo- on its innersurface(D. helonomadiverges some-
geny of the Megascolecidae proposed by what from this latter state).
Stephenson(1930)hasbeenoutlinedbyJamieson It should be noted, however, thatmostofthese
(1971) and&Dyne (1978). More recent studies unifying characteristics are symplesiomorphies:
(Jamieson Dyne, 1976; Dyne, 1984) have onlythe possession ofpharyngealtufting,genital
shown thatthe genus is farmore widespreadand setaglandsand ventral glandsrepresentprobable
speciose than previously believed, and that dis- synapomorphies.
tinctspecies-groups are recognisable. FivenewspeciesofDiplotremafrom southand
Thetwonewspeciesdescribedhereconfirmthe central Queensland were recently partly de-
concept of a species-group including the type- scribed and sketched (Blakemore, 1997). Fourof
speciesofthegenusandanumberofmorphologi- these differ from the fragilis group in lacking
callysimilarspecies inhabitingasimilarecotype. anteriornephridial tufting. A fifth,D. ambrosen-
The collection of these species at sites either sis,hasanteriortufts,but,asfortheotherspecies,
subject to periodic inundation, or pennanently the form and sculpturing ofthe penial, and geni-
below the water-table, testifies to their semi- tal, setae is notdescribed, considerably impeding
aquaticpropensities. This representsexploitation comparison, and no reference is made to ventral
of a niche largely unfilled by other Australian glands. Asthepenisetal follicles are described as
megascolecids.SomQSpenceriellaspeciesareknown ‘enormous’, it is unlikely that D. ambrosensis
from swampyhabitats, however(Dyne, 1984). belongs tothefragilis group.
SYSTEMATICS KEY TO SPECIES OF THE DIPLOTREMA
FRAGILISSPECIES-GROUP
Members of the Diplotremafragilis species-
group share the following character set: pros- 1. Dorsal pores present 2
tomium epilobous, nephropores in the vicinityof Dorsal poresabsent
cd, slender body form, S pores slightly presetal, D.proserpinensissp. nov.
intersegmental markings restricted to the region 2. Prostatic glands long, extendingat least into seg-
of segments XVI-XX, genital seta follicles mentXXI D.fragilis Sx>Qncex
strongly developed in VII, VIII or IX, often with ProstaticglandsnotextendingbeyondXX 3
associated glands, penial setae fine and delicate 3. Gizzardrudimentary; firstdorsal pores inthevi-
with littleornoornamentation,pharyngealtufted cinityof19/20; conspicuousglandsassociated
nephridia absent, large glandular mass (here with thegenital setae D. helonoma sp. nov.
termed ‘ventral glands’) located underthenerve- Gizzardwell-developed; firstdorsal pores in the
cord in XVII-XTX, spermathecae divided into a vicinityof7/8; noconspicuousglands associ-
subspherical ampulla and short, blunt digitiform ated with thegenital setae. D. tyagarah Dyne
. . .
488 MEMOIRS OFTHE QUEENSLAND MUSEUM
Diplotrema fragilis Spencer, 1900
(Fig- 1)
DiplotremafragilisSpencer, 1900: 31-32pi.4,figs4-6.
Diplotremafragilis^ Sweet, 1900; 1 14-5 pi. 14, fig.6.
Diplotremafragilis’, Michaelsen, 1907: 142.
Plutelliis(Diplotrema)fragilis’, Michaelsen, 1916: 61.
Diplotremafragilis, 1971: 100-102.
MATERIAL. Many specimens examined, I closely
(condition poor). SYNTYPES; National Museum of
VictoriaG3L Approx. 25°37’S, 15U37’E., Gayndah,
Sept., 1891-Qld.
DESCRIPTION.Length=31mm. Width=2.0mm.
Segments =111. Form cylindrical, anterior end FIG. DiplotremafragilisSpencer, 1900. Rightsper-
blunt and rounded, slightly bulbous, pigmentless mathecaofsegmentIX. Syntype{NMVG31).
buff in alcohol. Prostomium closed, epilobous
calciferous glands or other elaborations absent;
1/2; first dorsal pore (perforate) in 9/10. Setae 8
ppleersseogfmXenVtI,IIcloprseesleynpta,irtehdo,steheofveXntVrIaIlsaentadl XcoIuX- XinVt,estrienaechcionmgmefunlclewsidwtihthinaXbrVuIp,t aexdpeafninsiitoentyin-
phlosole lacking.
modified as enlarged penial setae, those ofVIII
and IX as genital setae. Nephropores not visible. Nephridia exclusively holonephric, commenc-
Clitellum annular, weakerventrally, overXIII- ing in 11, each invested in ahigh peritoneum and
XVI, dorsal pores obscured, intersegmental fur- forming a regular, simple lobe on each side, in
each segment; ducts long and avesiculate, enter-
rows and setaeonlysporadicallyvisible. 6 pores
ing the parietes in c-lines. Pharyngeal tufting
minute orifices equatorial, in XVIII. 6 field an absent.
approximatelycircular, somewhattumidareaex-
tending longitudinally from the setal arc ofXVI nelHsolparnedsreinct:inlaXrgae,ndtXhIi;cks-ewmailnleadl vsepseircmlaetsi2cpfauinr-s
to that of XIX, and laterally, in XVIII, beyond ofcompact, iobulated, and fairly small masses in
b-Wnes, small, indistinct, transversely oval papil- XI and XII. Prostatic glands 2 pairs offlattened,
lae(theprostaticporophores)presentin XVIIand
XIX, at the sites of the modified ventral setal tXuXbIuIl,arthoerpgoasntse,ritohreseatntteorXioXrIIpaLirTheextgelnadnidnsgarteo
couples. 9 pores minute orifices in a pair of sinuous,witheach bendcontiguouswiththenext,
considerablepapillae in frontofasetae, on XIV. ducts abruptly demarcated, slender, glossy, and
Spermathecal poreson apairofelliptical,slender running almost straight medianly. Anterior pros-
papillae, in 7/8, 8/9, with centres in b. tatesapproximatelytwicethesizeoftheposterior
Accessory markings: a pair ofhomy ridges pos- pair,though the length ofthe ducts is similar; the
teriorly in XIV, median to a (evidently misiden- ducts enter a median, internal glandular mass
tified by Spencer as the 9 pores); a median extending from XVII to XIX, and corresponding
transverselyellipticalprominencein 17/18ispos- with the external manifestation of the 6 field.
sibly a normal feature of the species. Segment Twopenial setafolliclesentertheglandularmass
VIII glandular, and appreciably widened. in the vicinity ofthe prostatic ducts, each with
Septa: 5/6 slightly, 6/7 and 7/8 moderately several setae;thesetaeslender,narrowlypointed,
strongly, and 8/9 and 9/10 very strongly thick- basally often expanded, gently curved orslightly
ened, the succeeding three septa slightly thick- sinuous, with the ectal 1/4 curved through as
ened, remainder thin. Pharyngeal glands muchasarightangle,theectalendsimple,orwith
well-developed, forming several tiers of flat- a crumpled appearance; minute notching present
tened, shortly palmate lobes in HI, anteriorly. ontheshaft,mostlyalmostinappreciable. Length
Dorsal bloodvesselsingle,continuoustothepos- mature seta = 1.4mm (mean of2), midshaft di-
teriorportion ofthepharynx, flattenedandadher- ameter = 40]im. Ovaries moderately stout, long,
enttothe intestine in XIV posteriorly; last hearts linguiform lobes ofseveral large, irregularly ar-
in XIII, those of X-XIII large, and increasing ranged oocytes; funnels moderate-sized, simple,
slightly in size posteriad, supra-oesophageal ves- also in XIII. Spermathecae 2 subequal pairs, in
sel present, but its limits not detemiinable be- VIIIand IX,eachwith amedianlydirectedovoid,
cause of maceration. Gizzard large, glossy, but or spherical ampulla and a lateral, equisized or
thin-walled, in V. Oesophagus narrow, VI-XIV, somewhat longer, iridescent concavo-convex
TWONEW SPECIES OFDIPLOTREMA 489
diverticulum. The ampulla and diverticulum in the incorporation of Plutellus {Diplotrema)
share a short narrow duct; length right sper- into a phylogenetic scheme (Michaelsen, 1916,
matheca of IX (base of ampulla to pore) = 1921), endorsed and expanded by Stephenson
0.64mm. A battery of genital setae present in (1930) where it occupied an intermediate posi-
segments VIII and IX, located behind each sper- tion, separating 'Acanthodrilus' from the truly
mathecal duct; the setae gently curving, with a megascolecin Plutellus. Stephenson adopted the
broadpoint, omam.ented withthe deep, elongate, term ‘accessory prostates’ for the organs illus-
crescenticnotchingcharacteristicofsuchsetae in trated by Sweet, while continuing to accept
acanthodriles, from very near the tip to slightly Spencer’s original diagnosis forthe genus.
less than halfway down the shaft, length mature After the true status of D. fragilis became
seta=9.98mm,midshaftdiameter=40pm (mean known, the New Caledonian forms remained
of2). within the Plutellus congeries until accommo-
REMARKS. There can be no doubt that the re- dated within the newly erected genus Eudiplo-
examinedspecimen is conspecificwiththe mate- trema. The uniqueness ofthe S system in these
frriaaglildiess,crtihbeetdypbeyoSfpeannceerw(g1e9n0u0s). aTshDeisppleoctirmeemna s(pJeacmiieessohnas&thBuesnnbetete,n 1s9a7ti9s)f.acTthoreilayutrheocrosgnhiasveed
presumablycontributedtothedescription. Points attemptedunsuccessfullytocollectfreshmaterial
ofagreementinSpencer'saccountwhichconfirm of D. fragilis, although a further quite distinct
the identity ofthe re-examined specimen are: the undeGsDcribed Diplotrema species was recovered
epilobous prostomium,the large oval midventral by from the banks of the Burnett River at
glandular patch in XVI-XIX, and the swollen, Gayndah, southeastern Queensland (SEQ).
glandular appearance ofsegment VIII. With re-
specttothe position ofthe 6 and prostatic pores, Diplotrema helonoma sp. nov.
however, Spencer’s account is erroneous, a de- (Figs 2, 3)
parturefromhis usual accuracy,possiblybecause ETYMOLOGY. Latin, helonoma, a dweller in the
ofthe small size ofthe species. No credence can marshes.
now beplacedonhisobservation ofonly asingle MATERIAL. (Holotype and 4 paratypes examined in
pairofprostateswithporesbehindthe 6 poreson detail) HOLOTYPE: ANICGD.95.144.1. BanBan
XVIII; the re-examined specimen has two pairs Springs (25°4rS,15l°49’E), SEQ, in black swampy
ofprostatic pores, on XVII and XIX, with the <S soilatandbelowthewatertable.Coll. G. DyneandA.
pores quite separate, on XVIII, as demonstrated Psopsetlcei,m9enJsunea1n9d74: fNruamgemreonutss;clitePllAatResA,TiYmmPaEtuSr;e
by Jamieson (1971). The presence of an addi-
tional pair ofprostatic glands was first noted by AFNUIRCTGHD.E9R5.M1A4T4.E1R,IcAolLl:ectAioNnICdGatDa.9a5s-f1o4r4.h1o.loStyapmee.
Sweet(1900) inherre-examinationofD.fragilis, locality, at side of spring. Coll. B. Jamieson and E.
though she termed these prostates ‘accessory Bradbury.21 May 1971;Numerousspecimens(mostly
glands’. All ofthe type-specimens, despite their aclitellate), notdesignated astype material.
poorconditionwhichprecludes illustration ofthe DESCRIPTION. Length > 24mm, 13mm. Width
1
genital field, are clearly referable to a single spe- (midclitellar) = 2.8mm. Segments ?, 182 (H -
cies. posterioramputee, PI). Pigmentless buffin alco-
Accepting Spencer’s original description, hol, clitellum with apinkish tinge, particularly in
Michaelsen (1910) placed D. fragilis within a freshly preserved material. Prostomium epilo-
monotypic section of the Acanthodrilinae, the bous 1/3, closed. First dorsal pore 19/20 (H, PI),
Diplotremacea. A subsequent examination of dorsal pores generally indistinct. Setae regularly
New Caledonian species (Michaelsen, 1913) disposed in 8 rows, uniform in size with the
genuinely havingthe S and prostatic ducts sepa- exception ofthe ventral setae ofXVII and XIX,
rate on XVlll (as erroneously described by which are enlarged as penial setae, and those of
Spencer, 1900, for Diplotrema fragilis), con- VIII and IX, modified as genital setae; ventral
vinced Michaelsenthatsuch an arrangementwas setal couples ofXVlll present. Nephropores vis-
closertotheplutelloid(andhence,Megascolecin) ible as minute depressions immediately anterior
grade of organisation than to the acanthodrilin to c in each segment, by a distance slightly ex-
system. Accordingly, the latter species and D. ceedingcd.
fragilis were referred to a separate subgenus Clitellum annular, obscuring the intersegmen-
within Plutellus. The seeminglytransitional con- tal furrows, though the setae remain prominent;
dition ofthe 6 terminalia in this group resulted clitellum developed over 1/3 XII-XVl (more so
490 MEMOIRS OFTHEQUEENSLAND MUSEUM
areolae in contracted specimens) is also glandu-
lar,occasionally(P4),withpore-likeimpressions.
Septa: 5/6 thickened, 6/7-9/10 moderately mus-
cularised, remainder thin. Dorsal blood vessel
single,continuousontothepharynx; lastheartsin
XIII, the commissurals in X-XIII large, and
female latero-oesophageal;thesupra-oesophagealvessel
pore is traceable from VI to XIV, attaining maximal
size in VI-IX, where its increased importance
apparentlycorresponds to adecline in the size of
the dorsal vessel. The remaining commissurals
decrease in size anteriad, and are dorso-ventral
prostatIc only. Gizzardsmall,softandreadilycompressed,
pore though with a slight muscular sheen, in V; oe-
malepore sophagusmoderatelywide, vascular, in VI-XVII,
calciferous glands or conspicuous outpouchings
prostatic
pore absent. Intestinal origin in XVII, dilating gradu-
ally posteriad, typhlosole lacking.
•genital
marking Holonephric: nephrostomes conspicuous on
long necks in ab\ avesiculate ducts open in line
withc-setae,enteringtheparietesslightlyanterior
FIG. 2. Diplotrema helonoma sp. nov. Male genital to the setal arc; nephridial bodies are enveloped
field. Holotype (ANICGD.95.144.1). ilnikethiunniptseriintoenaecuhm,saepgpmeeanrti.ngAnatserrieogrultaurftwianfgeri-s
dorsally, where it extends to beyond 1/2 XVII). absent.
S pores 2 orifices at the midpoints ofa pair of Holandric: 2 pairs of brightly iridescent sper-
narrow, ill-defined (shallow) seminal grooves matic funnels arepresentin X andXI,and2 pairs
linking the prostatic porophores ofa side; the 6 oflarge, acinous seminal vesicles in IX and XII,
pores are located barely presetally on XVIIL in thelatterpairconspicuouslythe larger, andoccu-
be,closertob. Dependentonthestateofmuscular pying virtually the entire ventral portion ofthat
contraction during fixation, the d field (defined segment. Prostatic glands 2 pairs ofcoiled, tubu-
laterally by the seminal grooves, anteriorly by a larorganswhich encroach on posteriorsegments
rhomboidal tumescence, and posteriorly by an- toagreaterorlesserdegree,penetratingthesepta.
othermarking), may beeithergenerally concave, The anterior pair is always the largerofthe two.
which sharpens the reliefofthe porophores, and Theprostaticducts areshort,straightandslightly
theridgejoiningthe d pores,oroffairlyunifonn muscular. The entire prostatic region is covered
ventrallywithaglandularmass thatappearstobe
scounmteoudr.duTrhiengfocnonpuelratcioonnd,itwiohnenistphreesguemniatballyoarsi-- an internal manifestation of the S field, and
which may be responsible for secretions neces-
fices would need to be raised for adpression to a saryforsuccessfulcopulation.Theprostaticducts
partner. The porophores are coincident with the and penisetal follicles pass through this mass
penial seta openings; the setae may be protruded
priortodischargingto the exterior. Penisetal fol-
in preserved specimens (H, P4), or withdrawn licles (consistingofconjoined aand b setal com-
(PI, P3); in the former case, each porophore ponents) are equipped with little copulatory
wouldappeartohaveonlyasinglesetaprotruding musculature; the setae are moderately long and
at any one time. $ pores a pair ofpre-setal slits, gently arcing, the ectal 1/8 ornamented with ir-
roughly aligned with ab, on XIV. Spermathecal regularly spaced, rounded, deep scallops ofvari-
pores2pairsin7/8and8/9,eachwithaprominent able diameter with somewhatjagged overhangs;
presetal lip, and with posteriorly adjacent tumes- these become more scattered and shallower en-
cences associated with the genial seta follicles. tally. Length ofmature setae = 1.9mm, midshaft
Accessory markings: a large, unpaired median diameter= 36.2pm (mean of3).
rhomboidal (or elliptical) swelling in 16/17 (de- Ovaries, consisting offlabellifonn clusters of
veloped to a greateror less extent in all clitellate oocytes, and medium-sized ovarian funnels, pre-
specimens examined); a similar marking in sent in XIII; no ovisacs demonstrable. Sper-
19/20; the d field (divisible into 4 depressed mathecae 2 subequal pairs in VIII and IX,
TWONEW SPECIES OFDIPLOTREMA 491
ences in the position ofthe seminal vesicles and
the dorsal pores and the conspicuous develop-
ment ofgenital setaglands in D. helonoma.
Diplotrema proserpinensis sp. nov.
(Figs 4, 5)
ETYMOLOGY. Named forthe type locality.
MATERIAL. HOLOTYPE: QMG5449. Myrtle
Creek, between Cannonvale and Proserpine,
(20°23’S,148°36’E), CEQ;frequentin mudinthebot-
tom ofand in the bank ofastagnant backwater. Coll.
B.G.M. Jamieson, 15 Jul 1966. PARATYPES 1-3:
QMG2887,2892.2893,collectiondataasforholotype.
OTHER MATERIAL; QMLGH2888, collection data
as for holotype.
DESCRIPTION. Length - 103, 82mm. Width =
1.5mm. Segments ^225, 175 (H, PI). Form cy-
lindrical, anterior end slightly bulbous over sev-
eral segments, pale in alcohol. Prostomium
FIG. 3.Diplotremahelonomasp.nov.Leftspermathe- pro-epilobous, dorsal pores absent. Setae closely
cal ofsegment IX. Paratype I. pairedthroughout, ventral setal couples ofXVIII
present, those ofXVIl and XIX modified as en-
discharging anteriorly in their segments; each larged penial setae, often protmding through the
consisting of a bipartite ampulla: a clavate or prostatic pores; those ofVIII replaced by genital
irregularsaccifonn portion, connectedbyabroad setae, situated on strongly protuberant papillae.
necktoasubsphericalcomponent.Asmall,hemi- Nephropores not externally recognisable.
spherical ‘diverticulum’ is sessile on the latter, Clitellum not developed. S pores seen slightly
opposite to the point ofattachmentofthe clavate
presetally, lateral of ^-lines, in shallow seminal
section of the ampulla; a medium-sized duct is grooves that link the porophores ofa side; pro-
sharedbytheampullaanddiverticulum;thelatter static pores 2 pairs, on medianly inclined dome-
is brightly iridescent, containing numerous intra- shaped papillae at the ab loci ofXVII and XIX.
moufrIaXls=pe1.r7mmcmham(bbeasres.oLfeanmgptuhlrliaghttosppoerrem).atChoenc-a Tarheeavceinrtcruamlsbcoridbyedsubryfatcheeisfoduerprperosssteadtiwcitphaipinltlhaee
spicuous genital setafollicles areassociatedwith and extending as far as intersegment 16/17 and
thespermathecae;thesearesurroundedbypromi- 19/20, its margins raised on each side as a longi-
nent, discrete, whitish glands, ofwhich there is tudinal ridge along which the seminal grooves
one per follicle in IX, and two in VIII. These run. $ pores minute, presetal in a or lines of
glands are prostate-like, both inoverall morphol- XIV. Spermathecal pores 2 pairs, in 7/8 and 8/9,
ogy and histologically, with a definite central
seen as elliptical areas, in /)-lines.
lumen leading to small ducts discharging at the
Accessory markings: large, glandular pad, ap-
point ofemergence ofthe genital seta from the
proximately circular in outline occupies most of
body wall; their function is unknown. The setae XX between the a setae, and encroaches some-
are fairly straight, ornamented overtheectal por- what into XIX. This marking is developed only
tionoftheshaft(includingthesomewhatswollen in the holotype to any significant degree, very
apicalregion)withconspicuous longitudinalflut- faintly in PI andnotseen inanyotherspecimens
ing; this appearance is due to the alignment of examined. ,
long roughlyparallel scallopswith fairly smooth
eddigaemse.teLren=g3t5h.o1fpmmat(umreeasnetoaf=3)1..34mm;midshaft tSDeeorpritsoaar:ltonboalnnoedodsetxvrceoslnsugedlliynsgminu9gs/lce1u,0laslarosimtseehweda,hratbtsuttinhtihXcoIksleeln;eadno.-f
REMARKS. Diplotrema helonoma is the geo- all the commissurals in VII-Xlll, only those in
graphically closest species to D. fragilis. The XII and XIII are large and heart-like. Further
similarities in overall morphology shared by the vascular details not determinable owing to the
two taxa leaves little doubt as to their phyloge- small size ofthe species and pronounced bleach-
netic propinquity. Points of divergence include ing. Gizzard large, in V; oesophagus narrow,
the muchreduced gizzard in D. helonoma, differ- moniliform, in VI-XIX, lacking pouching or
492 MEMOIRS OFTHE QUEENSLAND MUSEUM
mature seta = 0.75mm, midshaft diameter =
27.3pm(meanof2).
Ovaries, each with several strings oflarge oo-
cytes,andfunnels,presentinXI11,ovisacsabsent.
Spermathecae two pairs, in VIII and IX, the pos-
terior pair almost twice as large as the anterior.
Each with a large, somewhat irregular ampulla,
and a stout duct, at the ectal end of which, me-
dially,isasingle, large,ovoiddiverticulumwhich
maybealmostas largeastheampulla.Lengthleft
spermatheca ofIX = 0.66mm. Large genital seta
follicles present in VIII, apparently associated
with a glandular manifestation; the setae fairly
straight, the ectal 1/3 ornamentedwith aseries of
longitudinal scallops, giving a serrated appear-
ance. Length mature seta= 0.75mm (mean of3),
midshaftdiameter=27.3pm.
REMARKS. The absence ofdorsal pores in this
species may be connected with its semi-aquatic
mode ofexistence, since this loss is also seen in
the primarily limnic families Aliuroididae, Bi-
wadrilidae, Almidae, Lutodrilidae, Spargano-
philidae and the marine littoral megascolecid
Pontodrilus (see Jamieson, 1988). It is presum-
ably a response to the superfluity of coelomic
fluid lubrication in aquatic habitats. D. corni-
gravei, which also lacks dorsal pores, is notnec-
essarily related to members of the D. fragilis
FItaGl.f4i.elDdi.pHlooltorteympaep(roQsMeGr5pi4n4e9n)s.issp. nov. Malegeni- sinpetchieesf-gorromuepr. sTpheecideiss,aprpeecaorradnecde'offrdoomrssalwapomrpeys
ground’ (Jackson, 1931), has probably occurred
calciferous glands. Intestine commences in XIX
convergently.
or XX, a well-developed oesophageal valve pre- Whereasthe gutcontents ofD. helonoma con-
sent at 18/19 or 19/20; typhlosole absent. sist almost entirely ofsoft, partially digested or-
NephridiapresentatleastasfarforwardasVIII, ganic matter, the upper alimentary tract of D.
stomate, their avesiculate ducts entering the pa- proserpinensis was found to contain, inter alia,
rietes in a single series on each side, in c-lines; numerous irregular quartz grains (especially in
phar>'ngeal tufting absent.
Holandric: 2 pairs ofvery large, iridescent sper-
X
matic funnels, and sperm masses, free in and XI;
seminal vesicles lobed, in XI and XII, those ofXII
fillingthesegmentlongitudinally,thoseofIXsmaller.
Prostaticglandsslendertubes,thoseofXVllslightly
tortuous,andextendingintoXIXorXX;thoseofXIX
muchsmaller,tortuous,extendingintoXX;eachwith
a slender duct. Penisetal tbilicles well-developed,
each extending into its next posteriorsegment, four
ormoresetaetoabundle.Tliesetaecurvedgently,or
throughasmuchasasemicircle,ornamentedoverthe
distal sixth by a series ofwidely-separated, minute,
distallydirectedteeth,someorallofwhicharemem-
bersoftransversecirclets; thedistal extremityofthe
setae are 'laterally’ widened, and tenuinally form a FIG. 5. Diplotremaproserpinensis sp. nov. Left sper-
bulb with or without a small, apical point. Length mathecaofsegmentIX. Holotype (QMG5449).
TWONEW SPECIES OFDIPLOTREMA 493
the gizzard). A dietary divergence maytherefore JAMIESON, B.G.M. & DYNE, G.R. 1976. The acan-
account for the differential development of the thodriline earthworm genus Microscolex(Diplo-
gizzard in the two species. trema) in the Northern Territory of Australia
AustralianJournalofZoology24: 445-76.
LITERATURE CITED MICHAELSEN, W. 1907. Oligochaeten von Austral-
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