Table Of ContentRecordsoftheWesternAustralianMuseum22:17-22(2003).
A new genus and species of trigoniuline milliped from Western Australia
(Spirobolida: Pachybolidae: Trigoniulinae)
RichardL.Hoffman
VirginiaMuseumofNaturalHistory
Martinsville,Virginia24112,USA
Abstract-A new genus and species, Austrostrophus stictopygus, is described
fromnorthern Western Australia. The presence ofpunctate paraprocts, very
rare in spiroboloid diplopods, is shared with Ainigmabolus chisholmi of New
SouthWales,butapparentlyonlyasahomoplasiccondition.
INTRODUCTION austro (from Latin australis, in allusion to the
Whether considered a subfamily of the country of origin) + -strophus, a combining form
Pachybolidae or a discrete family, trigoniuline employedinmanygenericnamesinthissubfamily.
millipeds comprise a conspicuous element in the
fauna of southeastern Asia and Indonesia, whence
some 21 genera are currently recognized (Jeekel, Austrostrophusstictopygussp.nov.
2001). The group is, however, only marginally Figures1-10
represented in Australia, chiefly by Zygostrophus Material examined
and Ainigmabolus on the eastern edge of the Male holotype (WAM T46241), from Western
continent, and the recently described Speleostrophus Australia: BurrupPeninsula, Rocky HillatHearson
(Hoffman, 1994) from an island on the west coast. Cove (20°37'06"S, 116°47'05"E),R. Tealeleg. 22May
The recent discovery of a highly disjunct new 2002. Two immature females (WAM T46956) from
trigoniuline from Western Australia suggests that the same locality, 30 September 2002, R. Teale and
undercollecting along the western and northern M.Maier,leg.
periphery of the continent may account for this
apparentpovertyofAustralianspiroboloids.
Diagnosis
Withthecharactersofthegenus.
FamilyPachybolidaeCook
Holotype
mm
SubfamilyTrigoniulinaeAttems Adult male, length approximately 52
(broken), maximum diameter4.2 mm. 51 segments
Austrostrophusgennov + telson. Colour of recently preserved specimen:
prozona grayish, mesozona piceous to black,
Typespecies
metazona orange-brown. Mesozonal black pattern
Austrostrophusstictopygussp.nov. narrowed ventrad and absent above leg bases;
antennae, legs, sterna and pleural region similar in
Diagnosis colourtometazona.
A trigoniuline genus characterized by the Head without modifications, sides of genae
enlarged, distally excavate, gonopod coxae, into slightly convex but convergent ventrad;
whichtheelongated,slendertelopoditesarebasally interantennal and interocellarial widths 1.2 mm,
recurved. Submarginal belt of paraprocts ocellaria subrounded, maximum length 0.5 mm,
conspicuously set with large coarse punctures. about 36 ocelli in rows (4-5-7-6-6-5-3). 7+7 labral
Posterior edge of metazona with specialized fringe setae, 2+2 clypeal setae, those of each side widely
composedofsmalldenticulateprojections. separated. Antennae short, 2nd and 6th articles
longest, similar in size and shape, 3rd-5th shorter
Distribution and slightlymore triangular in outline; outerdistal
WesternAustralia. ends of 5th and 6th articles with rounded, slightly
convex sensory area, depigmented and appearing
Etymology semimembranous; 7th article very short, with four
Amasculineneologismcomposedoftheelements terminal sensory cones. Mentum of
18 R.L.Hoffman
Figure1 Posterior end ofbody, showing abbreviated form of the epiproct and coarsely punctate condition ofthe
paraprocts(SEMx32).
Figure2 Posterioredgeofmetazonumshowingthepalaeatefringe(SEMx200).
gnathochilarium with low but distinct median pattern of longitudinal striations; prozona with
ridge, prebasilar sclerite very thin. Mandibular several concentric striations below level of
baseswithoutlobesorothermodification. ozopores, curved posteriad at their ventral ends.
Lateral ends of collum subtriangular as usual in Pores prominent, located in mesozona below level
this family;pleuralregionof2ndsegmentproduced of lateral suture. Pleurotergal suture line visible;
ventrad and visible beneath end of collum as a sterna subquadrate, smooth (Figure 4). Metazona
digitiform lobe. Surface of collum and all body slightly elevated above level of mesozona, and
segments superficially smooth and polished: with caudallydecurvedslightly,becomingmuchthinner
magnification (60X) surface texture is a uniform and edged with a fringe composed of small
isodiameteric mesh, on which is superimposed a separate,denticulateunits(paleae)(Figures2,3).
Anewgenusandspeciesoftrigoniulinemilliped 19
3
5
Figures3-5 3.Twoindividualpaleae,greatlyenlarged(freehand,about2000x).4.Sternalregionofmidbodysegment,
legs removed to show coxal sockets and partial closure of posterior sockets. 5. Bases of leg pairs 2-6,
showingformofprocessesof3rdand4lhcoxae,posterioraspect.
Terminal segment (Figure 1) not produced withmoderateholdingability).Tarsalclawssimilar
dorsomedially; most ofparaprocts visible in dorsal in size and shape to those of other legs. Coxae of
aspect, their posterior edge set offby a moderately legs 3 and 4 produced into conspicuous, flattened
deep, broad groove beset with numerous large lobes, those of 4th coxa turned laterad apically
coarse punctures, disk ofparaprocts impunctate or (Figure5).
nearly so. Hypoproct transversely narrow, Anterior gonopods distinctive in the globosely
unmodified. enlarged coxae, deeply excavate on mesal side,
Posterior coxal cavities partially closed by small accommodating basal half of telopodites, anterior
median projection of sterna (Figure 4). Legs surface of coxae not produced into slender apices
relatively long, tarsi visible in dorsal aspect when (Figure6). Sternummodified"Y"shape,prolonged
extended; length ratio ofpodomeres in descending slightly behind coxae, sternal apodeme reflexed
order: 2-3-6-4-5-1. Podomeres essentially glabrous, caudad and not visible in anterior aspect; posterior
basal four with a single small seta at distal end extension of sternum separated as a discrete
ventrally,postfemurwith a distinctly larger setain elongate sclerite, narrowed at each end, and in
that position, tarsi typically with three large setae contactwithbasalendoftelopodite(Figure8,PXS).
(nearly length of tarsalclaw) in a ventrodistal row, Telopodite differing from typical trigoniuline
and a single large supra-apical seta. Anterior legs structure inbeing attached to anelevated posterior
without pads, although ventral surface of apical rim of the coxa, then abruptly recurved into cavity
podomeres appears depigmented and less of the latter, distal half reflexed ventrad behind
sclerotized than dorsal surface (perhaps endowed mediansternalprojectionasaslenderstalk,apically
20 R.L.Hoffman
Figures6-8 6. Left sideofanterior gonopods, anterior aspect. S, sternum, C, coxa, T, telopodite. 7. Lateral aspectof
gonopods (posterior pair concealed) with prostatic gland (stippled, at left) and retractor muscles of
telopodite indicated by broken lines inside coxa. 8. Posterior view of left anterior gonopod, showing
prolongation ofcoxa (C),withbase (TB) and distal shaft (TD) oftelopodite. PXS, posteriorextensionof
sternum;SA,reflexedsternalapodeme.
capitate just beyond apex of sternal projection discharges, and (2) a small, short, digitiform
(Figures7,9). projection.Distal2/3rdsofgonopod(telopodite)set
Posterior gonopod (Figure 10) generally off at nearly a right angle by a deep flexible
conforming to basic trigoniuline pattern: median articulation(A). Prostaticgroovecourses onmedial
sternal element (S) present, mergingeach side into side to a clear membranous subapical lappet; form
acoalescedcoxostemalregioncontaining(1)asmall oftelopodite and itsvarious lobes andprocessesas
chamber into which the prostatic duct (PD) showninFigure10.
Anewgenusandspeciesoftrigoniulinemilliped 21
Etymology
From the Greek stiktos (punctured) + pygos
(rump), in allusion to the coarsely punctate
paraprocts.
COMMENTS
Punctateparaprocts
Myinitialimpression,confirmedbyapreliminary
literature survey and survey of material at hand,
wasthatthischaracterwasnotknownfortheentire
order Spirobolida. Only through serendipity did I
notice the remark by Verhoeff (1937: 149) that in
Ainigmabolus chisholmi the “Analklappen neben dem
innenrande mit mehreren, unregelmassigen
Eindriicken." This species, a trigoniuline from New
South Wales, shows virtually no similarities in
Figure9 Obliqueposteromedianaspectofgonopodsto gonopod structure with A. stictopygus, and
showtheprominentflexureofthetelopodites apparently the paraproct modification must be
into the distal coxal cavity unique to this considered a "geographic homoplasy" peculiar to
genus.
Australia rather than any kind of synapomorphy
forthetwotaxa.
Metazonalfringe
In many orders of Diplopoda the posterior edge
of the metazona is provided with a thin,
transparent, sclerotized membrane ("limbus"),
variable both in width and ornamentation of its
edge.Thedefinitivetreatmentoflimbusoccurrence
throughout helminthomorph Diplopoda (Schmidt,
1962), recorded that in the three "trigoniuline"
families (Pachybolidae, Trigoniulidae,
Spiromimidae) "ein eigenlicher Limbus ist auch hier
nicht vorhanden" - at least in species of the six
genera examined. In one, Trigoniulus ceramicus, the
edge of the metazona itself is irregularly indented
and darkly pigmented, but the typical limbus
structure of a clear membrane with modified edge
is in no way approximated. The condition in
Austrostrophus is perhaps an elaboration of this
simpleform.Themarginofthemetazonaisnotably
thinner than the sclerite otherwise, but is opaque
and pigmented, no clearmembrane is present, and
the scale-like individual units (for which the term
paleae is suggested, singular palea) of the fringe
originate separately from the edge itself. Perhaps
thisexpressioncouldbedistinguishedby thename
"paleate". In those taxa in which a true limbus is
well-developed, e.g., Odontopygidae, the hyaline
membraneitselfcan usuallybe removed intactas a
continuous clear strip. In a general way, the true
limbusseemstobebestdevelopedintaxainwhich
other character systems are clearly derived, and
Figure10 Posterior gonopod, lateral aspect, sternal
apodeme concealed by the protractor and therefore indicative of an evolutionarily advanced
retractormuscles. PD, prostaticductwithits statusforsuchgroups.
sclerotized internal tube. S, sternum; A,
flexible articulation between coxal and Gonopods
telopoditalregions. Although it seems generally appreciated that the
22 R.L. Hoffman
sperm transfer process in most helminthomorph Relationships
diplopods is facilitated by a what is regarded as a As there remain a number of Papuasian
prostatic secretion (with ?enzymatic, ?nutritive, trigoniuline generaofwhichthe gonopodstructure
?bufferingfunction)theglandsthemselveshavenot is unknown or only poorly known, I am unable to
received a thorough comparative study. In this time to suggest any candidate sister-group for
Polydesmida, they lie in the coelom of segment 7 Austrostrophus. The singular form of the anterior
(oftenadjacentsegmentsaswell)and theirsecretion gonopodsisnotapproachedinanygenusknownto
is conducted through the gonocoxae to a prostatic me,northepresenceofamodifiedmetazonaledge.
groove originating at the base of the telopodite. In Curiously, the posterior gonopods offer no
Spirostreptida, the glands are generally located on corresponding pecularities, and in fact these
the posterior side of and in close proximity to the appendages tend tobe conservatively quite similar
gonocoxalfolds.Theyhavebeenscarcelynoticedin throughthesubfamily.
Spirobolida,buttheirsclerotized ductsenteringthe
bases of posterior gonopods are frequently
illustrated. Because of the excellent state of ACKNOWLEDGEMENTS
preservation of the holotype ofA. stictopygus I was I am very much indebted to my colleague Mark
able to determine that the glands are located in the Harvey (WAM), who on realizing that a
8th segment well behind the bases of the gonopods trigoniuline from Western Australia would be of
agonndoceoaxcah(iFsignueraer7l)y. Aaslloanrggeducats ctohnenepcrtescteoditnhge patatretnitciuolna.rIianmtermeustc,hbirnoduegbhttedtthoeDrs.peHcairmveenyftoormthye
coxosternal region, the central sclerotized tube the opportunity to examine and describe this
surrounded by a thick layer of what appears to be curious, disjunct spiroboloid, and to Patrick
additionalglandulartissue(Figure10). Brannon, VMNH technician, for the SEM
The function of the small internal chamber photography.
(Spermagrube of Verhoeff, 1937, Figure 13) remains
unknown; it appears too small to be an effective
reservoir. Some trigoniuline genera are credited REFERENCES
wiFtihgtuhreepr8essehnocwesoftthweousnuichqucehafmobremrsa.tion of the JeekeSlp,irCo.boAl.idWa.o(f20t0h1e).OAriebnitballiogarnadphiAcusctartaallioagnuereogfiotnhse
anterior gonocoxa in this genus. The posterior (Diplopoda).MyriapodMemoranda4:5-103.
surface is greatly elongated distal instead ofbeing Hoffman, R. L. (1994). Studies on spiroboloid millipeds.
short and basically transverse with the telopodite XVIII. Speleostrophus nesiotes, the first known
hinged along an exposed seam and apparently troglobiticspiroboloid milliped, from Barrow Island,
capable of very limited movement. In Western Australia (Diplopoda: Pachybolidae:
Anstrostrophus, the base of die telopodite is only Trigoniulinae).Myriapodologica3:19-24.
narrowly joined to the edge of the coxa, and Schmidt, D. (1962). Uber die taxionomische Wertigkeit
apparentlycapable ofbeingextended and retracted von Strukturen des Metazonit-Hinterrandes bei
(Figure 7 shows retractor muscles only, I did not Diplopoden.Senckenbergianabiologia43:65-80.
wishtolocate theextensorsbyfurtherdissection of Verhoeff, K. W. (1937). Ueber einige neue Diplopoden
thesinglespecimen). aus Australien. Records ofthe Australian Museum 20:
133-149.
Manuscriptreceived11November2002;accepted11 December
2002
