Late Ordovician trilobites from Tasmania

8/14/2019 Late Ordovician trilobites from Tasmania

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Late Ordovician trilobites from Tasmania: Styginidae, Asaphidae and

Lichidae

GREGORY D. EDGECOMBE, MAXWELL R. BANKS and DORIS M. BANKS

THIS STUDY on Ordovician (Gisbornian-Eastonian) trilobites from the Gordon Group ofTasmania follows an earlier account of the

Phacopida (Edgecombe et al. 1999). Herein wedescribe species belonging to the familiesStyginidae, Asaphidae and Lichidae. Speciestreated in this work originate from the BenjaminLimestone in the Florentine Valley and itscorrelates in the Gordon Group at Zeehan,Queenstown and Ida Bay (Fig. 1). Detailedaccounts of stratigraphy and biochronology forthese localities are presented by Banks & Burrett(1989), Laurie (1991) and Webby (1991). Positionsof units in the standard Tasmanian (OT)biostratigraphic scheme of Banks & Burrett (1980)follow Banks & Burrett (1989, fig. 6.8). The

trilobites described here occur in assemblagesOT14 to OT18 (Fig. 2), assigned to the Gisbornianand Eastonian stages (Nicoll & Webby 1996, chart2), or Caradoc (Burrellian to Streffordian) in theBritish standard (Webby 1998, fig. 4).

Grid references quoted in this paper lie withinGrid Zone 55G; the code 55G should precede allgrid references. These are quoted in the form DN50757045 Wedge 8112 Wedge 8112 being thename and number of the appropriate topographicsheet. The maps quoted are at scales of either1:100 000 (for map numbers beginning with 7 or 8)or 1:25 000 (for map numbers beginning with 3, 4,

5 or 6).

SYSTEMATIC PALAEONTOLOGYMost specimens figured in this work are housed

in the School of Earth Sciences, University of

Tasmania (prefixed UTGD). The remainder are inthe Palaeontology type collections, AustralianMuseum (AM F).

Order CORYNEXOCHIDA Kobayashi, 1935Suborder SCUTELLUINA Hup, 1953Family STYGINIDAE Vogdes, 1890Subfamily SCUTELLUINAE Richter & Richter,1955

Eokosovopeltis P ibyl & Van k, 1971

Type species.Bronteus romanovskii Weber, 1948,

from the Anderken Horizon (Caradoc), southernKazakhstan; by original designation. SeeKoroleva (1984) for revision.

Diagnosis. See Koroleva (1984, p. 81).

Discussion.EokosovopeltisP ibyl & Van k, 1971,andHeptabronteus Webby, 1974, were listed byLane & Thomas (1983) as junior synonyms ofKosovopeltis najdr, 1958, following Lane (1979)and Howells (1982). Koroleva (1984) maintainedthat Eokosovopeltis should be retained, but herrevision of the genus excluded Heptabronteus

majorWebby, 1974, from the Eastonian of NewSouth Wales. This species was interpreted by

EDGECOMBE, G.D., BANKS, M.R. & BANKS, D.M. 2004:07:23. Late Ordovician trilobitesfrom Tasmania: Styginidae, Asaphidae and Lichidae. Memoirs of the Association of Australasian

Palaeontologists 30, 59-77. ISSN0810-8889.

Late Ordovician (Gisbornian-Eastonian) trilobites from the Gordon Group of Tasmania includethe styginidEokosovopeltisgrandicurvatus sp. nov., the asaphidBasiliella choii sp. nov., and atleast two species of the lichid Amphilichas, one of which compares closely with A. encyrtosWebby, 1974, from coeval units in New South Wales. An effaced Basiliella from the GordonGroup at Zeehan may be conspecific withB. choii, which is based on silicified material from theBenjamin Limestone in the Florentine Valley. Characters of thoracic articulation are added to

criteria by which Eokosovopeltis Pribyl & Vanek, 1971, may be diagnosed. The Eastonian E.grandicurvatus is most similar to a species from the Chu-Ili terrane, Kazakhstan.

Gregory D. Edgecombe ([email protected]), Australian Museum, 6 College Street, Sydney,NSW 2010, Australia; Maxwell R. Banks and Doris M. Banks, School of Earth Sciences, Universityof Tasmania, GPO Box 252-79, Hobart, TAS 7001, Australia; received 26 February 2004.

Keywords: Trilobita, Amphilichas,Basiliella,Eokosovopeltis, Tasmania, Late Ordovician.


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Koroleva as intermediate betweenEokosovopeltisand Kosovopeltis, or was alternatively groupedby Ji (1986) with members ofLamproscutellumYin, 1980 (see discussion below). The synonymyofHeptabronteus is accepted, as its type species,H. atavus Webby, 1974, is certainly most closely

allied toE. romanovskii (Weber, 1948) and othercongeners treated by Koroleva (1984). Korolevas(1984) comparison ofEokosovopeltis andKosovopeltis does not address all criticisms ofLane (1979) in thatKosovopeltis was interpretedsolely with reference to its Ludlovian type species.Kosovopeltussvobodai certainly differs morestrikingly from Upper OrdovicianEokosovopeltisthan do stratigraphically earlier Silurian species

placed inKosovopeltis, for example, Llandoverytaxa described by Howells (1982) and Curtis &Lane (1997). However, merely recognising a singlelarge Caradoc-Lochkovian clade (Kosovopeltissensu Lane 1979; Howells 1982; Yin et al. 2000)risks dismissing phylogenetic information.Considerable variation exists within SilurianKosovopeltis [in the broad sense of Lane (1979)and more recent treatments].

Whittington (1999) considered thatHeptabronteus (=Eokosovopeltis: Whittington2000) species may merit recognition in a distinctgenus. We accept Korolevas (1984) retention ofEokosovopeltis , and assign the Tasmanian E.grandicurvatus sp. nov. to it. Characters bearingon this assignment include the posteromedian

pygidial rib, which does not widen or bifurcateposteriorly (in contrast toKosovopeltis? majorand Silurian Kosovopeltis). The narrow median

rib (see Fig. 5A, D for E. grandicurvatus) may,however, be a symplesiomorphy, e.g., bycomparison to Bronteopsis Nicholson &Etheridge, 1879 (Ingham & Tripp 1991, fig. 7g).Outgroup comparison with Bronteopsis,Eobronteus Reed, 1928, andProtobronteus najdr,1960, the most relevant outgroups (Webby 1974;Koroleva 1984), is hindered by those genera not

possessing the 7+1 rib arrangement that iscommon to (and presumedly apomorphic for)Eokosovopeltis and a large clade of post-Ordovician Scutelluinae (cf. P ibyl & Van k 1971,text-fig. 1). In Eokosovopeltis, including E.grandicurvatus (Fig. 5B, F), the pygidial doublureis very long (sag.), extending to the axial terminus,totalling about two-thirds the sagittal length ofthe pygidium. This state differs from a relativelyshorter doublure inLamproscutellum and SilurianKosovopeltis, and the doublure terminates wellbehind the axis inEobronteus (Whittington 2000,fig. 4.6). The eye ridge is indistinct or at most faint(Fig. 4H) inEokosovopeltis but is more raised inK.? major(Webby 1974, pl. 29, fig. 1) and in manySilurian Kosovopeltis, including Llandoveryspecies (Ludvigsen & Tripp 1990, pl. 2, figs. 5, 6,9, pl. 3, figs. 1, 3, 10). The pygidial axis ofEokosovopeltis lacks the strong trilobation ofKosovopeltis and other post-Ordovician

Fig. 1. Map of Tasmania, showing outcrop area ofGordon Group and locations of trilobite localities inthis study.

Fig. 2. Stratigraphic units for the Gordon Group in theFlorentine Valley. Calibration of Tasmanian faunalassemblages (OT10-20) and timescale from Banks &Burrett (1980), Laurie (1991), and Nicoll & Webby(1996).


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Scutelluinae, having at most weak furrowsdefining a pair of triangular lateral lobes (Fig. 5B).

Other characters cited in Korolevas (1984)diagnosis ofEokosovopeltis are shared with E.

grandicurvatus, including the glabella not beingdelimited anteriorly from the border, axial furrowsnot reaching the anterior margin, small to median-sized palpebral lobes, and rounded fixigenalimpressions (see Fig. 4A, H for each of these).The merging of the frontal lobe of the glabella andthe anterior cranidial border is not shared with

Bronteopsis and Eobronteus, but insteadresembles Kosovopeltis (Whittington 1999, fig.2.3, 2.4) andProtobronteus (Sinclair 1949, pl. 4,figs. 9, 10).

The thorax ofEokosovopeltis grandicurvatusindicates differences in the style of articulationcompared withKosovopeltisand post-OrdovicianScutelluinae. The thoracic pleurae of

Eokosovopeltis are more abruptly truncateddistally (Fig. 5F, 6 forE. grandicurvatus; Webby1974, pl. 28, fig. 14 for E. atavus) than in

Kosovopeltis and other post-Ordovician genera.In the latter group, the distal part of the pleural ribforms a backward curving spine, with anarticulating flange confined to the region adaxialto the fulcrum (Whittington 1999). In contrast, in

E. grandicurvatus, the distal parts of successiveribs are articulated with each other and anarticulating flange is present abaxial to the fulcrum

(Fig. 6).The delimitation ofEokosovopeltis and

Kosovopeltis also requires a consideration ofLamproscutellum Yin, 1980 (typeL.guizhouensis

Yin, 1980, from the Pagoda Limestone, UpperOrdovician, Guizhou Province, China). Ji (1986) placed the type species ofLamproscutellum insynonymy with Kosovopeltis? major (Webby,1974); the original treatment ofLamproscutellum(Yin 1980) made no comparison toHeptabronteusor its senior subjective synonym,Eokosovopeltis.Jis specific synonymy is rejected, sinceK.? majorlacks the distinctive pit-like glabellar furrows ofL.

guizouensis, the latter shared withL.shaanxiensisZhou in Zhou et al., 1982, from the Jinhe Formation,Shaanxi. Lamproscutellum also has strongparadoublural furrows on the fixigenae that are

lacking inK.? major.

Eokosovopeltis grandicurvatus sp. nov. (Figs. 3,4, 5A-F, 6; Table 1)

1974Eobronteus sp.; Corbett & Banks, pl. 3, figs.20, 21.

Diagnosis. Eokosovopeltis with axial furrowrelatively strongly divergent anterior to S2.Glabellar furrows faintly impressed on external andinternal surfaces of exoskeleton, none pit-like; S1and S2 confluent with axial furrow; L2 gently

swollen as round lateral lobe. Cranidium wideracross than , with relatively broad anteriormargin and wide preocular fixigenal field.

Etymology. In reference to the large radius ofcurvature of the anterior cranidial margin.

Type material. Holotype cranidium and associatedright librigena, UTGD 81124 (Fig. 4A, B, G),Benjamin Limestone, Upper Limestone Member,on former Adamsfield Track, about 1 km west ofbridge over Florentine River, DN 50757045 Wedge8112 (see Table 1 for dimensions). Paratypes:

cranidia UTGD 81123, 81130, cranidium andpygidium (two individuals) UTGD 81127, pygidiaUTGD 81128, 81136, from type locality; pygidiaUTGD 95789, 98895, Benjamin Limestone, near base of Upper Limestone Member, near EdenCreek, Florentine Valley, DN 590793 Tiger 4427;pygidium UTGD 58017, Benjamin Limestone, closeto The Settlement, Florentine Valley, DN 542884Wedge 8112; cranidium UTGD 57920, Ida BayLimestone, Adamson Traverse, up road toNewlands Quarry, Ida Bay, DM 888873 Leprena4818; partial thorax and pygidium UTGD 25072,Ida Bay Limestone, Ida Bay, quarry on road belowgap, DM 88808725 Leprena 4818; cranidium UTGD82722, pygidium UTGD 82677 and counterpart

Fig. 3.Eokosovopeltis grandicurvatus sp. nov.

Reconstruction in dorsal view.


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Fig. 4. A-J,Eokosovopeltisgrandicurvatus sp. nov. All specimens testiferous except E, latex cast from partlyexfoliated mould. A, B, G, dorsal view of holotype cranidium and external view of right librigena, lateral and

anterior views of cranidium, UTGD 81124, Benjamin Limestone, Upper Limestone Member, on former AdamsfieldTrack, Florentine Valley, x2.5; C, F, H, lateral, anterior and dorsal views of cranidium, (continued opposite)


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82679, Gordon Group, carbonaceous siltstoneexposed in trench on east side of Austral Creek,on western side of Smelters Hill, south of formerSmelters Quarry, Zeehan, CP 628580 Oceana 3635.The type material represents assemblage OT17(Eastonian Ea2). Samples from near the base ofthe Upper Member of the Benjamin Limestone areassigned to assemblage OT16 (Eastonian Ea1).Specimens from Smelters Quarry, Zeehan, co-occur with Pliomerina trisulcata and Erratencrinurus trippi in a fauna that representsassemblage OT15.

Description. Cranidial length (sag.) 65-70%maximum width across ; width across 1.1 timesthat across palpebral lobes; width across posteriormargin slightly greater than across palpebrallobes; midlength of palpebral lobe at about 75%length of cranidium; cranidium gently convex (sag.)except for anterior, terraced part, which curvessteeply down. Axial furrow subparallel betweenS0 and S2, narrow, moderately deep, divergentbackwards against L0, abruptly deflected outwardanterior to S2, effacing at paradoublural ridge farbehind anterior cranidial margin; frontal glabellar

lobe entirely merged with anterior cranidial borderalong the anterior glabellar margin, with no traceof preglabellar furrow. Glabella weakly arched (tr.).Glabellar furrows and muscle impressions on smallcranidium UTGD 57920 (Fig. 4D) serve aslandmarks for interpreting lobes on largerspecimens in which furrows are more effaced: S1shallow, confluent with axial furrow, directed

posteromedially; S2 shallow, confluent with axial

furrow at point where axial furrow abruptlydiverges, bifurcating into a weakly postero-medially oriented branch and a shorter, anteriorlydirected branch; S3 usually undefined on external

surface, where distinct represented by a narrow(tr.), slightly anteromedially oriented impression,effaced well inward of axial furrow (Fig. 4D); L2developed as large, gently swollen, circular bulgeadjacent to axial furrow. L0 gently convex (sag.,tr.), short (sag., exsag.), gently lengthened nearits distal corners; weak median node at midlengthof L0 on smallest cephalon (Fig. 4I). S0 moderatelydeep, longest medially where anterior margin isbowed forwards, abruptly effacing near axialfurrow. Preoccipital muscle impression large,transversely ovate, set against S0, slightly inwardof axial furrow. Fixigenal impression against L1

large, elliptical,defined by narrow, sharply incisedfurrow, with surface sculpture of longitudinallyaligned, elongate pits. Interocular fixigena ratherflat (exsag., tr.) except for gentle inflation onfixigenal impression. Palpebral lobe short (exsag.),narrow, crescentic, strongly curved, surfacecovered with horizontally oriented terrace lines;

palpebral furrow faint. Eye ridge at most faint,running anteromedially to axial furrow;

paradoublural ridge anterior to and parallel to eyeridge. Posterior border furrow narrow (exsag.),sharply impressed, slightly sinuous, extending tofacial suture; posterior border very narrow

(exsag.), lacking bulge over fulcral socket. Terraceridges strongly developed on anterior 20-25% ofcranidium in dorsal view, running parallel toanterior margin; terrace ridges on L0 convexforwards; small cranidium UTGD 81127 withconcentrically arranged, anteriorly convex terraceridges on posterior part of glabella, indistinct inlarger specimens. Small, shallow pits pervasiveon glabella.

Librigenal field encircling eye slightlydepressed, narrow (tr.) depressed ring widening

posteriorly, apparently defining paradoubluralline. Posterior part of field faintly convex (tr.);

anterior part gently concave; lateral border furrowlacking. Visual surface convex, evenly decreasingin height posteriorly. Terrace ridges orientedanterolaterally across posterior half of field, wavy,abruptly curved back near margin, lacking onanterior half of field; terrace ridges on field spacedfarther apart than those on and adjacent to lateralmargin; marginal terrace ridges extend onto dorsalside of librigena anteriorly, confined to margin

UTGD 81130, locality as for Fig. 4A, x2.5 (C, F), x4.5 (H); D, dorsal view of cranidium, UTGD 57920, Ida BayLimestone, Adamson Traverse, Ida Bay, x4; E, dorsal view of partly exfoliated cranidium, UTGD 82722, GordonGroup, carbonaceous siltstone on east side of Austral Creek, western side of Smelters Hill, Zeehan, x2; I, dorsalview of cranidium, UTGD 81127, locality as for Fig. 4A, x4; J, dorsal view of pygidium, UTGD 81128, localityas for Fig. 4A, x3.

Table 1. Dimensions forEokosvopeltis grandicurvatus.All in mm; asterisk indicates inferred width frommeasurements on one side of fragmentary specimen.

81124 81127 81130

L cranidium 15.9 4.6 14.7

W - 24.2 6.9 21.6*

W - 22.0* 5.6* 18.7

W L0 10 2.5 9.4

81127 81136 95072 98895

L pygidium 14.6 15 18.7 15.4

W pygidium 21.0* 22.4 30.3 23.4*

L axis 3.5 4.4 - 4.8

W axis 7.0* 8.1 10 8.7

L doublure - 8.6 11.5 -


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Fig. 5. A-F,Eokosovopeltisgrandicurvatus sp. nov. A, dorsal view of pygidium, UTGD 81127, locality as forFig. 4A, x2.5; B, dorsal view of partly exfoliated pygidium, UTGD 81136, locality as for Fig. 4A, x2.5; C, D,lateral and dorsal views of pygidium, UTGD 98895, Benjamin Limestone, near base of Upper LimestoneMember, near Eden Creek, Florentine Valley, x2.5; E, F, lateral and dorsal views of partial thorax and pygidium,UTGD 25072, Ida Bay Limestone, Ida Bay, x2. G, H,Kosovopeltis? major(Webby, 1974), Malongulli Formation,Copper Mine Creek, WNW of Mandurama, New South Wales; latex casts from external moulds. G, ventral viewof hypostome and rostral plate, AM F.125431, x2.6; H, external view of right librigena, AM F.125432, x2.5.


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posteriorly; fine pits most obvious betweensubmarginal terrace ridges but also scattered overfield. Genal angle unknown.

Number of thoracic segments unknown (partsof eight in UTGD 25072: Fig. 5F). Axis about 36%width of thorax in last three segments; axial furrownarrow, shallow. Axial ring gently arched (tr.).Pleurae gently turned down at fulcrum; posterioredge of rib with a short (exsag.) articulating flangeextending from fulcrum to near distal edge of rib;

fulcral process or socket not visible on dorsalexoskeletal surface. Pleurae abruptly truncated,with angular posterior tip. Terrace ridgesconcentric, convex forward on axis; terrace ridgeson pleurae gently undulating, subparallel,converging backwards adaxially. Doublureextending inwards to fulcrum; terrace ridges ondoublure aligned exsagittally, convex adaxially.

Pygidium semicircular, length (sag., includingarticulating half ring) about 65% of maximumwidth; anterior margin transverse to fulcrum, thengently directed backwards; anterolateral cornersharply rounded. Axial furrow narrow, shallow.

Axis (measured across maximum width ofarticulating half ring) nearly 40% maximum widthof pygidium. Articulating half ring 8-10% lengthof pygidium sagittally, narrowing (exsag.) distally,anterior margin transverse across most of itswidth; articulating furrow narrow, shallow, convexbackwards. At most one ring furrow weaklydefined; some specimens entirely lacking ringfurrows; at most weak trace of pair ofanteromedially directed furrows on axis, definingtriangular lateral lobes (Fig. 5B); longitudinal profileof axis nearly flat or faintly convex (sag.); axialterminus rounded, defined by weakly impressedfurrow. Postaxial region 70-75% of pygidial length,gently convex (sag.). Pleural field with seven

paired ribs that gently widen distally and medianunpaired rib; median rib approximately parallel-sided, of similar width distally as adjacent pairedribs. Interrib furrows all narrow, of equal, moderatedepth; first interrib furrow effacing near lateralmargin, successive furrows terminating

progressively farther from margin to delimit anarrow border. Sculpture of gently undulatingterrace ridges running subtransversely acrossentire pleural field, scalloped, convex anteriorly

across each rib, gently recurved forwards nearlateral margin; concentric, anteriorly convexterrace ridges on axis. Inner margin of doublureextending to axial terminus; dorsal surface ofdoublure with weak impression of ribs across mostof its width; doublure bearing more than 20concentric, slightly undulating terrace ridges thatrun approximately parallel to pygidial margin.

Discussion. Apparently most similar isEokosovopeltis weberi Koroleva, 1984, describedfrom cranidia from the Caradoc strata in the Chu-Ili Mountains (Chu-Ili terrane), Kazakhstan. This

species shares the marked anterior expansion ofthe glabella seen in E. grandicurvatus, andlikewise has S1 confluent with the axial furrow(Koroleva 1984, pl. 8, figs. 8, 9). Specific distinctionis made based on the wider (tr.) preocular fixigenaand inflated L2 lateral lobes inE. grandicurvatus,and the restriction of strong terrace ridges to theanterior part of the cranidium, versus coveringthe entire cranidium inE. weberi.

In comparison with Eokosovopeltis atavus(Webby, 1974), from the Eastonian of New SouthWales, and the similarE. romanovskii (Weber,1948) from Kazakhstan,E. grandicurvatus has awider, less anteriorly convex anterior margin, anda wider (tr.) preocular fixigenal field; S2 is confluent

Fig. 6.Eokosovopeltisgrandicurvatus sp. nov. Dorsal views of partial thorax and pygidium, UTGD 25072, IdaBay Limestone, Ida Bay, x4.3, x3.8.


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with the axial furrow rather than isolated, and S1is weakly impressed rather than slot- or pit-like.

Eokosovopeltis grandicurvatus isdistinguished from the other Eastonian styginid

in New South Wales, Kosovopeltis? major(Webby, 1974), by stronger divergence of thecephalic axial furrow anteriorly, the fixigenalimpression being more strongly delimited by afurrow, the eye ridge being weaker, the

posteromedian rib on the pygidium neitherexpanding nor bifurcating, and less markedsegmentation of the pygidial axis (four pairs of

pits are distinct inK.? major). New collections ofK.? majorinclude librigenae with the genal anglemore complete than in previously figured material,showing a short genal spine (Fig. 5H), and ahypostome articulated to the rostral plate (Fig.

5G).The Tasmanian species differs fromKosovopeltis sp. of Yin et al., 2000, from the PagodaFormation (Caradoc), Guizhou Province, China, inhaving the cephalic axial furrows effaced fartherback, a more mushroom-shaped glabella, S1 more

posteriorly directed, a weaker occipital node, andhaving a relatively shorter pygidial axis with moreindistinct segmentation. The Chinese species hasfive weakly defined axial rings, and appears to bemore closely related to K.? major than toEokosovopeltis.

Order ASAPHIDA Salter, 1864Superfamily ASAPHOIDEA Burmeister, 1843Family ASAPHIDAE Burmeister, 1843

Basiliella Kobayashi, 1934

Type species.Asaphus barrandi Hall, 1851, fromthe Black River Group (Caradoc: Mohawkian),near Plattsville, Wisconsin, U.S.A.; by originaldesignation.

Diagnosis. See Lee & Choi (1992, p. 173).

Discussion. Zhou & Fortey (1986) discussed thedifficulty in distinguishing Basiliella andParabasilicus Kobayashi, 1934. They regardedParabasilicus as an effaced Basiliella, andemployed the two taxa as subgenera ofBasilicusSalter, 1849. Lee & Choi (1992) revised the typespecies ofParabasilicus,P. typicalis Kobayashi,1934, from the Jigunsan Formation (Llanvirn) ofKorea, and endorsed the idea that Parabasilicusis an effacedBasiliella. Lee & Choi (1992) placed

Parabasilicus in synonymy with Basiliella, andprovided a new diagnosis for the genus, which isfollowed herein. A new species from Tasmania,described below, represents another effacedBasiliella. The elimination of the genal spines isthe most significant deviation from othercongeners.

Basiliella choii sp. nov. (Figs. 7-9)

Etymology. For Professor Duck Keun Choi, inrecognition of his work on this genus and otherOrdovician trilobites.

Diagnosis. Basiliella with anterior section of facialsuture diverging forwards at about 50 degrees. S0and S1 weakly impressed on dorsal exoskeletalsurface; S3 effaced. Blunt genal angle lackingspine. Pygidial ring furrows and all but first pleural

Fig. 7.Basiliellachoii sp. nov. Reconstruction in dorsalview.

Fig. 8.Basiliellachoii sp. nov. Silicified specimens, all from upper part of Lower Member of Benjamin Limestone,Settlement Road, Florentine Valley. A-C, dorsal, anterior and lateral views of cranidium, UTGD 128657, x8; D,dorsal view of anterior part of cranidium, UTGD 128658, x4; E, dorsal view of posterior part of cranidium,UTGD 128659, x4; F, dorsolateral view of thoracic segment, UTGD 128675, x3; (continued opposite)


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G, dorsal view of posterior part of small cranidium, UTGD 128676, x6.7; H, dorsal view of anterior part ofcranidium, UTGD 128660, x4; I, N, external and internal views of librigena, UTGD 128661, x4.4, x3.8; J, externalview of holotype cranidium, UTGD128656, x4; K, external view of librigena, UTGD 128662, x5; L, externalview of librigena, UTGD 128663, x4; M, external view of librigena, UTGD 128664, x6; O, internal view oflibrigena, UTGD 128665, x3.2.


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Fig. 9.Basiliellachoii sp. nov. Silicified specimens, all from upper part of Lower Member of Benjamin Limestone,Settlement Road, Florentine Valley. A, ventral view of hypostome, UTGD 128666, x4.3; B, ventral view ofhypostome, UTGD 128667, x5.3; C, D, dorsal and ventral views of hypostome, UTGD 128668, x3.6; E, I,dorsal and ventral views of pygidium, UTGD 128669, x4; F, H, lateral and dorsal views of pygidium, UTGD

128670, x4.5; G, dorsal view of pygidium, UTGD 128671, x4.5; J, dorsal view of pygidium, UTGD 128672, x4;K, L, ventral and dorsal views of pygidium, UTGD 128673, x3.8.


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furrow shallow; interpleural furrows effaced.Exoskeleton densely pitted, relatively large pits

pervasive on glabella and librigenal field.

Type material. Holotype silicified cranidium UTGD128656 (Fig. 8J), from the upper part of the LowerMember of the Benjamin Limestone (Strophomenacf. oklahomensis Assemblage of Laurie 1991),Settlement Road section SR 17 (Laurie 1991, fig.7), DN 55808674 Gordonvale 4428, FlorentineValley. Paratypes UTGD 128657-128673, 128675,128676, from type locality. The type stratumrepresents assemblage OT14 (Gisbornian).

Description. Glabellar length (excluding L0) 11.4mm in holotype; largest fragmentary librigenaeindicate glabellar length 140% larger than holotype.

Cranidium slightly shorter (sag.) than its maximumwidth across posterior border; width across fromabout 75% width across palpebral lobes (Fig. 8A)to nearly equal (Fig. 8D); midlength of palpebrallobe at about 65% length (sag.) of cranidium. Axialfurrow shallow against frontal glabellar lobe, faintagainst interocular fixigena, effaced in postocularregion, including against L0. Glabella elongatesubrectangular, with rounded anterior margin,length about 75% of cranidial length, gentlyconvex (sag., tr.); width across frontal lobe about65% length of glabella (excluding L0). S0 weak onexternal surface, gently convex backwards, lacking

abaxial deepening (e.g., pits); small median glabellarnode immediately in front of L0, weakly raised ondorsal surface, more prominent on ventral surface;S1 shallow, broad, directed posteromedially,usually faint on dorsal surface, more distinct onventral surface, effaced well in advance of S0;some small specimens with S1 moderately deepalong its anterior half (Fig. 8G). Baccula notdistinct from L1. S3 indistinct. L0 slightly morethan 10% length (sag.) of cranidium, evenly longacross its width, with gentle, even arching (tr.).Preglabellar field absent; anterior cranidial borderfurrow confluent with preglabellar furrow across

anterior margin of glabella; anterior border furrowsimilarly shallow abaxially. Glabella and anteriorcranidial border densely pitted. Anterior sectionof facial suture diverging at about 50 degreesbetween and , weakly concave outward in

posterior part, straight in anterior part;anterolateral cranidial margin straight, convergingto a blunt median angulation; anterior borderweakly arched (tr.), gently and evenly wideningmedially, nearly flat across most of its width;anterior part of median angulation flexeddownward. Palpebral lobe narrow, crescentic,nearly 30% length of cranidium, sloping upwardsabaxially, raised about as high as glabella; palpebralfurrow faint. Posterior section of facial suture

strongly divergent backwards, slightly convexanteriorly, turned sharply backwards immediatelybefore reaching posterior margin. Posterior borderfurrow lacking on cranidium. Small articulating

boss on posterior margin of fixigena, just abaxialto outer edge of occipital doublure.Eye socle narrow (tr.), base defined by

distinctly impressed furrow. Inner half of librigenalfield gently convex (tr.), densely pitted, outer halfsteeply turned down to border furrow, with slightlymore subdued pitting. Lateral border furrow ofeven, moderate width and depth along most oflength, abruptly shallowing posteriorly, effacedalong posterior part of librigenal field; posteriorborder furrow undefined. Lateral border slightlywider than lateral border furrow in dorsal view,with shelf-like inner half and steeply declined outer

half. Genal angle blunt. Doublure flat to lateralborder, then abruptly flexed dorsally, extendinginwards to more than twice width of lateral border,bearing many evenly spaced terrace lines; severalspecimens with small circular opening, apparently

panderian opening, just inside inner margin ofdoublure slightly anterior to genal angle (Fig. 8N).

Hypostomal middle body subquadrate, gentlyconvex (tr.), gently widening posteriorly to amaximum width about 85% of its length; anteriormargin of middle body biconvex. Lateral borderfurrow shallow; middle furrow distinctly deeper,especially in front of maculae. Maculae strong,

crescentic. Middle body and borders with fine,undulating, subtransverse terrace ridges; terraceridges on posterior projections of border deflectedforward near lateral margin. Posterior fork deep,its inner margins gently convex, medial margingently concave; projections triangular, with blunttips. Doublure wide over projections, forming amedially concave and dorsally subangular ridgealong each projection; small posterior wing

projecting subdorsally from inner margin ofdoublure on projection; outer part of doublurewith several terrace ridges running parallel to lateralmargin. Lateral and posterolateral border with

narrow (tr.), raised marginal ridge.Thorax known only from fragments of

disarticulated segments. Axial furrow narrow,nearly effaced. Axis weakly arched (tr.). Pleuralfurrow deep, straight, running parallel to edge ofarticulating facet along inner two-thirds of pleura;anterior pleural band forming a steep crest. Pleuraltip with weakly oblique ventrolateral edge,rounded anterior corner, blunt posterior corner.Inner margin of doublure at fulcrum, with tapering

posterior part of inner margin extending furtheradaxially.

Pygidial length about 70% of width in mostcomplete large specimen (Fig. 9H); largerfragmentary specimens apparently relatively


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Fig. 10.Basiliella cf.B. choii sp. nov. A-D, limestone in shale below Smelters Quarry, Zeehan; E-I, SmeltersQuarry. All internal moulds except H, I, partly testiferous. A-C, dorsal, anterior and lateral views of cranidium,

UTGD 82669, x2; D, dorsal view of cranidium, UTGD 24626, x2.6; E, external view of librigena, UTGD 24558,x2.3; F, ventral view of hypostome, UTGD 24605, x2; G, ventral view of hypostome, UTGD 96551, x3; H, I,dorsal and lateral views of pygidium, UTGD 24121, x2.5.


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wider. Axial furrow shallow against first ring,moderately deep against rest of axis, including

posteromedially, more strongly convergingagainst anterior six rings than posteriorly. Axis

slightly more than 30% of pygidial width anteriorly,gently arched (tr.) anteriorly, increasingly archedand elevated well above pleurae posteriorly; axisfaintly convex in longitudinal profile, terminatingin advance of border furrow; up to 10 axial ringsdefined by shallow ring furrows, each about one-third width of axis; ring furrows obscure acrosssagittal third of axis in dorsal view, definedventrally (Fig. 9I); ring furrows effaced in posteriorthird of axis. Inner part of pleural field gentlyconvex (tr.), then steeply curving down to borderfurrow; postaxial field steeply sloping to borderfurrow. First pleural furrow narrow, deep, straight,

abruptly effacing at border furrow; severaladditional pleural furrows faintly impressed;interpleural furrows effaced except for weak traceof first one; posterior third to half of pleural fieldunfurrowed. Anterolateral corner of pygidium(articulating facet) rounded. Border furrow broad,shallow; border evenly wide, about one-eighthlength of pygidium in postaxial region, flattened,moderately sloping downward to margin. Doublurewider than border, with shallow, rounded

posteromedian embayment; numerous terracelines along entire width of border, more dense inits inner half.

Discussion. The nearly complete effacement ofthe glabellar furrows in most specimens (includingS1, which is usually pronounced in Basiliella)and lack of a genal spine distinguishB. choii fromall congeners. Relevant species comparisons arewithBasiliella emodi (Salter in Salter & Blanford,1865) from the Central Himalaya, India (see Morris& Fortey 1985, pl. 3, figs. 1, 3), andB. satunensisKobayashi & Hamada, 1964, from Thailand, bothof which likewise have largely effaced pygidialfurrows, and have been identified as closely relatedto each other (Fortey & Cocks 2003, p. 275). In

addition to the suppression of S1 and the bluntgenal angle, further distinction fromB. satunensiscan be made based on the pitted rather than striateexoskeletal sculpture (compare fig. 8H, L withKobayashi & Hamada 1964, pl. 9, figs. 2, 8). FromB. emodi, the new species differs in having a moreelongate pygidium (Morris & Fortey 1985, pl. 3,fig. 1).Basiliella typicalis (Kobayashi, 1934) fromKorea has a similar course of the anterior sectionof the facial suture, and shares a relatively strongconvergence of the pygidial axial furrow againstthe first few axial rings, as well as a deeply forkedhypostomal margin (Lee & Choi 1992, fig. 4). Itdiffers from the new species in having transcurrentS3, deeper S1, and median nodes on the pygidial

axial rings.

Basiliella cf. B. choii sp. nov. (Fig. 10A-I)

Occurrence. Siltstone in Gordon Group, SmeltersQuarry, Zeehan, grid reference CP 623582 Pieman7914 (cranidium UTGD 24656, librigena UTGD24558, hypostomes UTGD 24605, 96551, pygidiumUTGD 24121); limestone in shale below SmeltersQuarry (cranidia UTGD 24626, 82669, 82746).Smelters Quarry specimens are assigned toassemblage OT15.

Discussion. The type material forBasiliella choiiis from the Lower Member of the BenjaminLimestone (assemblage OT14). Slightly youngermaterial (OT15) from Smelters Quarry at Zeehan

may be conspecific, though comparison iscomplicated by the different styles of preservation(the former silicified, the latter moulds in siltstone).Internal moulds show the typically basiliellineorientation of S1 and prominent preoccipitaltubercle (Fig. 10A), and have a low, narrow (tr.)longitudinal median crest along the length of thefrontal glabellar lobe (Fig. 10A, B, D); this featureis indistinct on the ventral surface of the frontallobe in most silicified specimens. A similar crest isobserved on the internal mould inPseudobasilicusfortis Webby, 1973 (Webby 1973, pl. 53, fig. 12),andP. plantaensis Astini et al., 1986 (Astini et al.

1986, pl. 1, fig. 3). S3 is represented on the internalmould by a narrow (tr.), shallow, transverse furrow,confined to the abaxial part of the glabella oppositethe anterior edge of the palpebral lobe (Fig. 10A,B). A librigena from Zeehan (Fig. 10E) has a fieldthat is slightly wider than the largest specimensfrom the type locality, and has a relatively shallowlateral border furrow. No consistent differencesare observed between hypostomes. The anteriorwings are broken in all silicified specimens, butthe mould material shows them to be narrow (tr.),about 80% of the maximum width across the lateralborder (Fig. 10G), and separated from the lateral

border by a strong antennal notch.

Order LICHIDA Moore, 1959Family LICHIDAE Hawle & Corda, 1847Subfamily TETRALICHINAE Phleger, 1936

AmphilichasRaymond, 1905

Type species. Platymetopus lineatus Angelin,1854, from the Boda Limestone (Ashgill), Dalarna,Sweden; by monotypy.

Diagnosis. See Thomas & Holloway (1988, p. 216-217).


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Fig. 11. A-E, H-I,Amphilichas cf. A. encyrtos Webby, 1974. A-C, dorsal, lateral and posterior views of cranidium,UTGD 98257a, internal mould from Benjamin Limestone, Lower Limestone Member, near Settlement Road,

Florentine Valley, x3; D, E, anterior and dorsal views of cranidium, counterpart UTGD 98257b, latex cast fromexternal mould, x4; H, I, dorsal views of pygidium, UTGD 98256, latex cast from external mould (UTGD98256b), internal mould (UTGD 98256a), locality as for Fig. 11A-E, x4. ( continued opposite)


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Amphilichas cf. A. encyrtos Webby, 1974 (Figs.11A-E, H-I, 12G-I)

cf. 1974Amphilichas encyrtos ; Webby, pl. 32, figs.

11-12, pl. 34, figs. 10-21.1974Amphilichas (Tetralichas); Corbett & Banks,pl. 3, figs. 13, 14.

Occurrence . Benjamin Limestone, LowerLimestone Member, near Settlement Road,Florentine Valley, DN 568863 Wedge 8112(counterpart moulds of cranidium UTGD 98257a,b; counterpart moulds of pygidium UTGD 98256a,b); Lords Siltstone, Locality 11 of Corbett & Banks(1974, fig. 4), on former track between WestfieldRoad and Cashions Creek Road, Florentine Valley,DN 567847 Gordonvale 4428 (counterpart moulds

of cranidium UTGD 81271, 81272); shale in GordonGroup, Queenstown, small ridge close to SportsGround, east of former railway line east of QueenRiver about 200 m upstream from bridge overQueen River on Penghana Road, CD 807408Gormanston 3834 (cranidia UTGD 25606, 54344);siltstone in Gordon Group, Winduss Road, 1.5 kmnorth of Gunns Plains, DQ 199312 Forth 8115(cranidium AM F12250, hypostome AM F12251,

pygidium AM F106372). Samples from the LordsSiltstone, the shale at Queenstown, and siltstonenear Gunns Plains are from assemblage OT15.

Discussion. Amphilichas encyrtos Webby, 1974,was based on cranidia and hypostomes from theQuondong Limestone, Bowen Park Group, incentral west New South Wales. Some Tasmaniancranidia are very similar to that of A. encyrtos,

particularly samples from assemblage OT15 in theFlorentine Valley (Figs. 12H, I) and Queenstown(Fig. 12G). These share a tubercle where thelongitudinal furrow intersects S0, and cephalictuberculation of the same size and density. In NewSouth Wales (Webby 1974, pl. 32, fig. 11) andTasmanian (Fig. 12I) specimens, the medianglabellar lobe has four larger tubercles: a pair

anterior to midlength, and two unpaired tubercleson the posterior half of the lobe. The palpebrallobe of the holotype bears coarse granules, smallerthan the tubercles on the lobe in the Tasmanianspecimens (Fig. 12I). In the Tasmanian material,the median glabellar lobe is slightly narrower thanthe composite lateral lobe at the level of the eye(Fig. 12G, H, I), versus equally wide in the NewSouth Wales material. Given the paucity ofavailable specimens from Tasmania as well as New

South Wales, the issue of possible conspecificityis unsettled.

An Amphilichas cranidium from the LowerLimestone Member of the Benjamin Limestone

near Settlement Road in the Florentine Valley (Fig.11A-E) resemblesAmphilichas cf. A. encyrtos inthe proportions of its glabellar lobes, presence ofa tubercle at the intersection of the longitudinalfurrow and S0, and the four larger tubercles onthe median glabellar lobe described above. Itdiffers from typical A. encyrtos and the LordsSiltstone and Queenstown samples in havingfewer, but relatively coarser tubercles on theglabella and L0; coarse tubercles are especiallyconcentrated on the posterior part of the medianand lateral glabellar lobes (Fig. 11E). Thelongitudinal glabellar profile is more convex (Fig.

11B) than in the holotype ofA. encyrtos (Webby1974, pl. 32, fig. 12), particularly along the posteriorpart of the median glabellar lobe. The SettlementRoad material is likely specifically distinct fromA.encyrtos based on these differences, but the smallsample size and limited data on variation incranidial characters forA. encyrtos in its type areamake a formal separation dubious.

The pygidium is unknown forA. encyrtos in itstype area, but is available for the Settlement Road(Fig. 11H, I) and Gunns Plains samples. It has thesecond axial ring defined by a shallow transversefurrow across most of the width of the axis, effaced

abaxially and weakly distinct medially. Thepostaxial piece is narrow, bounded by furrowsnearly as deep as those against the axis, remainingsharply impressed to their point of convergenceat the posteromedial margin of the pygidium. Thefirst pleural furrow is deep and gently concaveforwards; the second pleural furrow is entirelyeffaced. The first two pleurae have pointedterminae, the third a rounded lappet. The axis and

pleurae have a rather uniform sculpture of mixedfine and moderate sized tubercles.

Compared to specimens just described, anAmphilichas pygidium (Fig. 11G) from the

Benjamin Limestone near Dawson Settlement inthe Florentine Valley (DN 542883 Gordonvale4428) has a more deeply impressed second pleuralfurrow; the second ring furrow is more deeplyincised as a pair of slightly posteromediallydirected grooves but wholly effaced sagittally;coarser tubercles are present (including a pair onthe second axial ring); and the postaxial piece iswider and bounded by shallower furrows. In theabsence of associated sclerites its specific

F, Amphilichas sp. Ventral view of partial hypostome, UTGD 81125, Benjamin Limestone, Upper LimestoneMember, on former Adamsfield Track, Florentine Valley, x3. G, Amphilichas aff. A. encyrtos Webby, 1974.Dorsal view of pygidium, UTGD 59025, latex cast from external mould, Benjamin Limestone, near DawsonSettlement, Florentine Valley, x2.5.


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Fig. 12. A-F, Amphilichas sp. nov. A. Smelters Quarry, Zeehan. All partly exfoliated. A-C, dorsal, lateral andposterior views of cranidium, UTGD 82734, x3.7; D, dorsal view of cranidium, UTGD 24638, x3; E, dorsal view

of cranidium, UTGD 24682, x3; F, dorsal view of cranidium, UTGD 82736a, x3.7. G-I, Amphilichas cf. A.encyrtos Webby, 1974. G, cranidium UTGD 54344, latex cast from external mould, (continued opposite)


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assignment is unknown, but the characters listedabove suggest that it is distinct fromAmphilichascf. A. encyrtos.

Amphilichas sp. nov. A (Fig. 12A-F)Occurrence. Siltstone in Gordon Group, SmeltersQuarry, Zeehan, grid reference CP 623582 Pieman7914 (cranidia UTGD 24570, 24638, 24682, 82703,82719 and counterpart 82734, 82736, hypostomeUTGD 82733); limestone in shale below SmeltersQuarry, Zeehan (cranidium UTGD 82709);Queenstown, small ridge close to Sports Ground,east of former railway railway line east of QueenRiver about 200 m upstream from bridge overQueen River on Penghana Road (cranidia UTGD54346, counterpart 54384, UTGD 54366). Samples

from Smelters Quarry and Queenstown representassemblage OT15.

Discussion. Collections from Zeehan andQueenstown include anAmphilichas species thatis readily distinguished from Amphilichas cf. A.encyrtos by having a much constricted medianglabellar lobe. The width across the narrowestextent of the median lobe is about half themaximum width of the composite lateral glabellarlobe; as few as three tubercles span the medianlobe at its narrowest point (Fig. 12A, D). Becausethe cranidia are fragmentary and partly exfoliated,

with pygidia and librigenae being unknown, wehave retained this species in open nomenclature.Compared to other species with complete

longitudinal glabellar furrows and a narrow medianlobe, such as A. tibetanus (Salter in Salter &Blanford, 1865) (Morris & Fortey 1985, pl. 6, fig.1),A. karakanensis Weber, 1948 (Weber 1948, p.9, figs. 9-12), andA. ardmillanensis (Reed, 1914)(Tripp 1980, pl. 4, fig. 21), distinctive for theTasmanian species are a few greatly enlargedtubercles across the posterior part of the occipitalring (Fig. 12A-C), several coarse tubercles amidstmany smaller tubercles on the glabella, a moderate

divergence of the longitudinal furrows betweenthe narrowest part of the median lobe and S0, anda wide (tr.) composite lateral lobe. Other charactersof possible diagnostic value are: longitudinalfurrows strongly deflected outwards anteriorly,with the median lobe slightly overhanging theanterior cranidial border sagittally; palpebral lobenarrow (tr.) and unornamented (Fig. 12D); a

pronounced fulcral bulge on the posterior marginof the posterior cranidial border (Fig. 12B andUTGD 54384). Some specimens show a

suppression of tuberculation on the anterior partof the median glabellar lobe, with small pits presentinstead (Fig. 12E), or pits between the tubercles,as well as obsolecence of tubercles on the anterior

and anterolateral parts of the composite lateralglabellar lobes (Fig. 12E).

Amphilichas sp. (Fig. 11F)

Occurrence . Benjamin Limestone, UpperLimestone Member, on former Adamsfield Track,about 1 km west of bridge over Florentine River,grid reference DN 50757045 Wedge 8112(hypostome UTGD 81125), assemblage OT17.

Discussion. A fragmentary tetralichinidhypostome from the Upper Limestone Member

on the former Adamsfield Track (Fig. 11F) is theonly lichid sclerite retrieved from that locality. Itssimilarity to the hypostome ofAmphilicas encyrtos(Webby 1974, pl. 34, figs. 10-17) allows for a genericassignment. In light of its stratigraphic separationfrom confidently assigned material ofAmphilichascf. A. encyrtos and Amphilichas sp. nov. A, thehypostome cannot be referred to one of thosespecies with confidence.

ACKNOWLEDGEMENTSWe thank Yong Yi Zhen (Australian Museum)

for photography, Alan Lam for trilobite

reconstructions, Kathi Stait (formerly Universityof Tasmania) for facilitating loans, and SteveWestrop (University of Oklahoma) and ananonymous referee for helpful reviews.

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