Hoplolichoides Allolichas Autoloxolichas and Akantharges And the Classification of Lichid Trilobites

Hoplolichoides, Allolichas, Autoloxolichas and Akantharges,and the classification of lichid trilobites

Hoplolichoides, Allolichas, Autoloxolichas et Akantharges,et la classification des trilobites Lichidae

David J. Holloway a,*, Alan T. Thomas b

aInvertebrate Palaeontology, Museum Victoria, PO Box 666E, Melbourne, Victoria 3001, AustraliabSchool of Earth Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom

Received 9 November 2000; accepted 24 July 2001

Abstract

Hoplolichoides PHLEGER, 1936 and Autoloxolichas PHLEGER, 1936 are revised based on redescription of their type species,H. conicotuberculatus (NIESZKOWSKI, 1859) and A. sanctamathiae (SCHMIDT, 1885) respectively. Hoplolichoides is considered to bemost closely related to Hoplolichas DAMES, 1877, and both are included in a revised Homolichinae. Autoloxolichas is restricted to its typespecies, and other species previously assigned to the genus are placed in Allolichas KRUEGER, 1992, the concept of which is expanded.Autoloxolichas and Allolichas are included together with three other genera and subgenera in the Subfamily Platylichinae, previouslyconsidered to be a junior synonym of Homolichinae. The hypostomal morphology previously regarded as important in uniting homolichineand platylichine genera is now regarded as primitive for the Lichidae. Metopolichas GÜRICH, 1901, previously included tentatively in theHomolichinae on the basis of its hypostomal morphology, is reassigned tentatively to the Lichinae. The trochurine ‘Acanthopyge’ erbeniMEISCHNER, 1965, from the Givetian of Germany, is assigned to Akantharges PHLEGER, 1936, permitting clarification of the pygidialmorphology of the genus. Akantharges and Ceratarges GÜRICH, 1901 are unique amongst lichids in having a curved, transverse ridge onthe posterolateral cranidial lobe, suggesting that these genera may have been derived from a common ancestor. © 2002 Éditionsscientifiques et médicales Elsevier SAS. All rights reserved.

Résumé

Les genres Hoplolichoides PHLEGER, 1936 et Autoloxolichas PHLEGER, 1936 sont révisés sur la base d’une redescription de leursespèces types respectives: H. conicotuberculatus (NIESZKOWSKI, 1859) et A. sanctamathiae (SCHMIDT, 1885). Hoplolichoides estconsidéré comme le genre le plus proche de Hoplolichas DAMES, 1877. Les deux genres sont inclus dans les Homolichinae égalementrévisés. Autoloxolichas ne contient que son espèce-type et d’autres espèces rapportées aurapavant à Autoloxolichas sont placées dansAllolichas KRUEGER, 1992 dont la définition est ainsi étendue. Autoloxolichas et Allolichas sont inclus avec trois autres genres etsous-genres dans la sous-famille des Platylichinae que l’on considérait avant comme un synonyme des Homolichinae. La morphologie del’hypostome considérée autrefois comme importante (unissant les genres homolichines et platylichines) est à présent considérée commeprimitive pour les Lichinae. Metopolichas GÜRICH, 1901 qui avait été placé dans les Homolichinae sur la base de sa morphologiehypostomale est placé dans les Lichinae. Le trochuriné ‘Acanthopyge’ erbeni MEISCHNER, 1965 du Givétien de l’Allemagne est attribuéà Akantharges PHLEGER, 1936 permettant une classification de la morphologie pygidiale du genre. Akantharges et Ceratarges GÜRICH,

* Corresponding author.E-mail addresses: [email protected] (D.J. Holloway), [email protected] (A.T. Thomas).

Geobios 35 (2002) 111–125

www.elsevier.com/locate/geobios

© 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.PII: S 0 0 1 6 - 6 9 9 5 ( 0 2 ) 0 0 0 1 4 - 1

1901 sont uniques chez les lichidés par leur crête transversale courbe sur le lobe cranidial postéro-latéral, suggérant que ces deux genresdérivent d’un ancêtre commun. © 2002 Editions scientifiques et médicales Elsevier SAS. Tous droits réservés.

Keywords: Trilobites; Lichidae; Systematics; Ordovician; Devonian

Mots clés: Trilobites; Lichidae; Systématique; Ordovicien; Dévonien

1. Introduction

The trilobite genera Hoplolichoides, Autoloxolichas andAkantharges, all erected by Phleger (1936), were reviewedby Thomas and Holloway (1988) in their revision of theLichida. Additional information on these genera has becomeavailable subsequently, providing the opportunity to clarifytheir taxonomic concepts as well as to assess their likelyrelationships. In the light of our new data, we assignHoplolichoides to a revised Homolichinae. The SubfamilyPlatylichinae is resurrected to accommodate Allolichas andAutoloxolichas, together with other genera.

Hoplolichoides has not generally been accepted as adistinct genus, most authors (Warburg, 1939; Hupé, 1953;Tripp, 1957, 1959; Balashova, 1960) considering it to be ajunior subjective synonym of Hoplolichas DAMES, 1877.Thomas and Holloway (1988) recognised Hoplolichoidesbut expressed reservations about its utility as an indepen-dent genus, stating that the pygidial morphology wasinsufficiently known for a full comparison with othergenera. In the present paper, we redescribe cephala andpygidia of the type species, H. conicotuberculatus (NIESZ-KOWSKI, 1859), and compare it with other species con-sidered to be congeneric, showing that Hoplolichoideswarrants recognition as a separate genus.

Autoloxolichas was based on Lichas sanctamathiaeSCHMIDT, 1885, and that was the only species listed byPhleger (1937) as belonging to the genus. The genus wasbriefly diagnosed by Phleger (1936) as differing fromPlatylichas in lacking the continuation of the longitudinalfurrow behind the bullar lobe, but Öpik (1937) dismissedthis supposed difference as being due to a misunderstandingand placed sanctamathiae in Platylichas. Tripp (1957,1959) and Dean (1974) also considered Autoloxolichas to bea junior synonym of Platylichas. Thomas and Holloway(1988) recognised Autoloxolichas as a distinct genus towhich they assigned, in addition to sanctamathiae, a num-ber of species resembling ‘Lichas’ laxatus MCCOY, 1846.We now believe, based on the study of plaster replicas of thetype material of sanctamathiae, that Autoloxolichas shouldbe restricted to that species, and that the other speciesincluded in the genus by Thomas and Holloway (1988)should be placed in Allolichas KRUEGER, 1992, theconcept of which should be expanded.

Akantharges was until relatively recently known onlyfrom the type species, Lichas gourdoni BARROIS, 1886,the material of which is strongly deformed and difficult tointerpret. A well preserved cranidium of an undescribed

species of Akantharges from the Devonian of Morocco wasillustrated by Thomas and Holloway (1988, pl. 14, figs 299,200, 303), who based their concept of the genus largely onthat specimen. We have subsequently been able to examinethe material of ‘Acanthopyge’ erbeni MEISCHNER, 1965from the Givetian of Germany, and recognised that thisspecies belongs to Akantharges. The specimens of erbeniare relatively well preserved and clarify some of thecharacters of the genus, particularly pygidial characters.

2. Systematic palaeontology

Morphological terminology used here is that of Thomasand Holloway (1988). Stratigraphical nomenclature followsthe revised Ordovician series proposed by Fortey et al.(1995, 2000).

Several of the species dealt with herein were documentedby Schmidt (1885). Until recently, the specimens from thisand other parts of Schmidt’s series of trilobite monographswere not available for study. Photographs of most ofSchmidt’s specimens are now available on the World WideWeb at the site entitled ‘Catalogue of the trilobites figured inFriedrich Schmidt’s ‘Revision der ostbaltischen silurischenTrilobiten’ (1881–1907)’ by D.L. Bruton, O.A. Hoel,L.T. Beyene and A. Yu. Ivantsov (internet addresshttp://www.toyen.uio.no/palmus/schmidt/index.html). Thespecimens are also listed but not illustrated in Bruton et al.(1997).

Repositories of specimens are denoted by the followingabbreviations: CNIGR, Central Scientific-Research Geo-logical Exploration Museum named after F.N. Chernyshev,St Petersburg; GIE, Institute of Geology, Tallinn TechnicalUniversity; Gö, Geologisch-Paläontologishes Institut undMuseum, Georg-August-Universität, Göttingen; MB, Mu-seum für Naturkunde, Humboldt Universität, Berlin; RM,Naturhistoriska Riksmuseet, Stockholm.

Family: LICHIDAE Hawle & Corda, 1847Subfamily: HOMOLICHINAE Phleger, 1936Diagnosis – S1 effaced or almost effaced, so that bullar

lobe is more or less completely fused with L1b; resultingcomposite lobe circumscribed by furrows, except in Leioli-chas which has longitudinal furrow effaced externally.Palpebral lobe narrow, of almost uniform width throughout,moderately curved in outline. Hypostome with middle bodyas wide across posterior lobe as across anterior lobe, orwider; shoulder situated level with posterior border furrow;border greatly expanded and flap-like at and behind

112 D.J. Holloway, A.T. Thomas / Geobios 35 (2002) 111–125

shoulder. Pygidium with two to three pairs of pleuralfurrows and six to eight marginal spines (spines absent inLeiolichas); anterior and posterior pleural bands flattened.

Genera included – Homolichas SCHMIDT, 1885;Conolichas DAMES, 1877; Hoplolichas DAMES, 1877;Hoplolichoides PHLEGER, 1936; Leiolichas SCHMIDT,1885; Otarozoum THOMAS & HOLLOWAY, 1988.

Remarks – S1 is effaced, or almost so, in Conolichas,Hoplolichas, Hoplolichoides and Otarozoum, the bullar lobealmost completely fusing with L1b. The resulting compositelobe is circumscribed by the longitudinal and axial furrows,and by the transverse furrow in front of L1a (Fig. 1.1–4).The longitudinal furrow is effaced externally in Leiolichasbut is present on internal moulds, though very shallowposteriorly (see Warburg, 1939, pl. 3, figs 7, 8). On someinternal moulds of Leiolichas cranidia, S1 is also present butvery weak. It meets the axial furrow just behind theintersection of the latter with the palpebral furrow, and isdirected strongly obliquely backwards towards the point atwhich the longitudinal furrow abruptly shallows (Fig. 1.5).This glabellar structure is different from that in genera suchas Platylichas, Autoloxolichas and Metalichas, which werepreviously included in the Homolichinae (Tripp, 1957,1959; Thomas and Holloway, 1988), but which we nowplace in the Platylichinae (see below). In these genera, theaxial furrow is effaced alongside L1b, and the bullar lobe iscircumscribed by the longitudinal furrow, S1, and the shortsection of axial furrow between the anterior end of thelongitudinal furrow and the outer end of S1 (Fig. 1.6–7).

Metopolichas GÜRICH, 1901 was tentatively included inthe Homolichinae by Thomas and Holloway (1988) byweighting its hypostomal morphology, despite the fact thatit resembles Lichas and some other Lichinae in glabellarstructure (longitudinal furrow not generally extending be-hind S1, with which it is united in a curve; S1 commonlyincomplete abaxially). The hypostome of Metopolichasresembles those of Homolichinae and some Platylichinae,rather than Lichinae, in being wider than long and having adeep posterior border furrow (see Thomas and Holloway,1988, pl. 11, figs 227, 231, 235). However, hypostomes ofTetralichinae (e.g. Thomas and Holloway, 1988, pl. 12, figs250, 267) and Trochurinae (e.g. Chatterton and Ludvigsen,1976, pl. 19, figs 17–20) also share these character states,which we now consider primitive for lichids as a whole andthus not useful for inferring relationships within the family.The interpretation of these character states as primitive issupported by their presence in the oldest known lichid,Metopolichas? klouceki (RUZICKA, 1926) from the lowerTremadoc of the Czech Republic (see Thomas and Hollo-way, 1988, pl. 11, fig. 236). In view of the similarities inglabellar structure between Metopolichas and some Lichi-nae we now assign the genus to that subfamily.

Notwithstanding their similarity in the primitive charac-ter states mentioned above, hypostomes of Homolichinaediffer from those of Platylichinae in that the middle body isas wide across the posterior lobe as across the anterior lobe,

or wider, instead of narrower; the border is more expandedin width at the shoulder, where it has a flap-like appearance;and the shoulder is situated somewhat farther back, oppositethe posterior border furrow rather than opposite the middlefurrow or the posterior lobe of the middle body (compareThomas and Holloway, 1988, pl. 10, fig. 196 and Fig. 3.4herein).

In comparing the thoracic and pygidial structure oflichines and Platylichas, Whittington (in press) noted that inboth the inner parts of the thoracic pleurae are wide andevenly inflated, and the pleural furrows extend almost to thepleural tips. The pygidial pleural bands in these taxa are of

Fig. 1. Cranidial morphology in Homolichinae (1-5) and Platylichinae(6-8). 1. Conolichas (after Thomas and Holloway 1988, pl. 7, fig. 141). 2.Hoplolichas (after Thomas and Holloway 1988, pl. 8, fig. 155). 3.Hoplolichoides (after Fig. 2.6). 4. Otarozoum (after Thomas and Holloway1988, pl. 8, fig. 161). 5. Leiolichas (after Thomas and Holloway 1988, pl.7, fig. 147). 6. Platylichas (after Warburg 1939, pl. 11, fig. 1c). 7.Autoloxolichas (after Fig. 3.1 and Thomas and Holloway 1988, pl. 10, fig.213). 8. Allolichas (after Thomas and Holloway 1988, pl. 10, fig. 188 andKrueger 1992, pl. 1, fig. 1b). Dashed lines indicate furrows that are veryweakly developed, or present only on internal moulds; see text for details.Non-standard abbreviations: af, axial furrow; b, bullar lobe; cl, compositelobe; lf, longitudinal furrow; of, occipital furrow.Morphologie du cranidium chez les Homolichinae et les Platylichinae. 1.Conolichas (d’après Thomas et Holloway 1988, pl. 7, fig. 141). 2.Hoplolichas (d’après Thomas et Holloway 1988, pl. 8, fig. 155). 3.Hoplolichoides (d’après Fig. 2.6). 4. Otarozoum (d’après Thomas etHolloway 1988, pl. 8, fig. 161). 5. Leiolichas (d’après Thomas et Holloway1988, pl. 7, fig. 147). 6. Platylichas (d’après Warburg 1939, pl. 11, fig. 1c).7. Autoloxolichas (d’après Fig. 3.1 et Thomas et Holloway 1988, pl. 10, fig.213). 8. Allolichas (d’après Thomas et Holloway 1988, pl. 10, fig. 188 etKrueger 1992, pl. 1, fig. 1b). Les hachures indiquent des sillons trèsfaiblement développés ou présents seulement sur les moules internes.Abbréviations non standards: af, sillon axial; b, lobe bulleux; cl, lobecomposé; lf, sillon longitudinal; of, sillon occipital.

D.J. Holloway, A.T. Thomas / Geobios 35 (2002) 111–125 113

similarly low convexity, are divided by the pleural furrow,and are extended distally into the marginal spines. This kindof thoracic and pygidial structure occurs in homolichinesalso (e.g. Otarozoum, see Thomas and Holloway, 1988, pl.8, figs 167–170) and, by comparison with other trilobites,probably represents the primitive condition for the Lichidae.The pygidial pleural bands of Hoplolichoides are moreinflated than is usual for a member of these subfamilies, andthe genus is derived in that regard.

Genus Hoplolichoides PHLEGER, 1936Type species – Lichas conico-tuberculata NIESZ-

KOWSKI, 1859, from the Kukruse Stage (C2, lower Cara-doc) of Estonia; original designation.

Other species – H. curvifrons (WARBURG, 1939); H.furcifer (SCHMIDT, 1885).

Stratigraphical and geographical range – MiddleLlanvirn–lower Caradoc; Russia (St Petersburg district),Estonia, Sweden, Norway.

Diagnosis – Homolichine having glabella with L1b in-distinctly differentiated from bullar lobe by slight backwarddeflection and/or shallowing of longitudinal furrow, andvery weak S1. Frontomedian and bullar lobes moderatelyconvex (sag., exsag.), frontal lobe slightly overhangingmedial part of anterior border in palpebral view; bullar lobewith long axis subparallel to sagittal line; minimum width ofmedian lobe less than width of bullar lobe measured acrosssame transverse line. Occipital ring strongly elevated medi-ally, with large paired spines. Cranidial tuberculation verycoarse. Pygidium transverse, approximately 160% as wideas long (sag.), with three pairs of marginal spines and smallposteromedian spine; third pair of spines very short andbroad, subtriangular or lobate, situated very close to secondpair of spines. Axis approximately 30% maximum pygidialwidth anteriorly and 50% sagittal length. Pleurae withprominent border that is transverse between second pair ofspines; first two pleural furrows and furrow defining post-axial band terminating at inner edge of border; third pleuralfurrow not defined; anterior and posterior pleural bands wellrounded (exsag.).

Remarks – Large paired occipital spines are preservedonly in the type species, the occipital ring being incompleteposteriorly in known specimens of the other two speciesassigned to the genus. We would not exclude a species fromHoplolichoides solely on the absence of these spines.

Hoplolichoides shows the greatest similarities withHoplolichas and Otarozoum. The similarities with Hoploli-chas include the presence of large occipital spines (unpairedin Hoplolichas), the weak differentiation of L1b by abackward deflection of the longitudinal furrow and a faintS1, the very coarse cranidial tuberculation, the absence ofthe third pygidial pleural furrow, and the well developedborder on the posterior part of the pygidium. Pygidia ofsome species of Hoplolichas also resemble Hoplolichoidespygidia in having a very short, broad marginal spine situatedimmediately behind the second spine, and/or an unpairedposteromedian spine (e.g. Warburg, 1939, pl. 8, fig. 5;

Neben and Krueger, 1971, pl. 35, figs 15, 17). Of thesesimilarities, we do not attribute great taxonomic importanceto the presence or absence of occipital spines, while theweak differentiation of L1b may be a primitive characterstate, compared with the condition in Conolichas andOtarozoum (in which L1b is indistinguishable), and thus notindicative of close relationship. On the basis of the pygidialsimilarities, however, we consider Hoplolichas to be mostclosely related to Hoplolichoides. Hoplolichas differs fromHoplolichoides in that the glabella is more convex (sag.,exsag.), the frontal lobe being more inflated and markedlyoverhanging the anterior border in palpebral view; theminimum width of the median lobe is greater (rather thanless) than the width of the bullar lobe measured across thesame transverse line; and the pygidium is not as transverse.In addition, pygidia of Hoplolichas species typically havemuch longer marginal spines, there is no spine situatedimmediately behind the second spine, and the posterior pairof spines are situated very close together, commonly beingfused proximally (e.g. Thomas and Holloway, 1988, pl. 8,fig. 162).

Otarozoum resembles Hoplolichoides in the moderatecranidial convexity and the proportions of the glabellarlobes, but differs in the absence of large occipital spines;L1b is not differentiated at all from the bullar lobe; thecranidial tuberculation is much finer; there is no pygidialborder; the third pygidial pleural furrow is impressed; thethird pair of pygidial marginal spines is situated very closetogether; and the pygidium has no posteromedian spine. Thepygidium of Otarozoum is very similar to that of Conoli-chas, suggesting that these genera are most closely relatedto each other.

Apart from conicotuberculatus and furcifer, Phleger(1937) also included in Hoplolichoides the species Lichas(Hoplolichas) plautini SCHMIDT, 1885, L. (H.) longispina[sic] SCHMIDT, 1885 and Lichas media [sic] POMPECKI,1890. The last two belong to Hoplolichas, as indicated bythe proportions of the glabellar lobes, the strongly over-hanging frontal lobe and the large, unpaired occipital spinein the illustrated cranidium of medius (Pompecki 1890, pl.2, fig. 25, 25a), and the three pairs of long marginal spines,the posteriormost pair situated fairly close together, in theholotype pygidium of longispinus (Schmidt 1885, pl. 2, fig.25). In plautini, Schmidt (1885, pl. 2, figs 17–24) associatedcranidia and an incomplete cephalon of Hoplolichas typewith pygidia having the morphology of Hoplolichoides. Weconsider these pygidia to belong to Hoplolichoides furcifer,a species based on cranidia from the same locality andhorizon as plautini. Schmidt chose to assign the pygidia toplautini rather than to furcifer because one of the pygidia ispreserved beneath an incomplete cephalon of plautini.However, examination of a plaster replica of this specimen(CNIGR 36/11101) revealed that the pygidium is not inenrolled position beneath the cephalon, and consequentlythere is no reason to conclude that both cephalon andpygidium belong to the same individual as believed by


Schmidt. In addition, the pygidium is so incomplete (moreso than shown by Schmidt 1885, pl. 2, fig. 17b) that it is notpossible to determine whether it belongs to Hoplolichoidesor Hoplolichas. The fragmentary pygidium later assigned tofurcifer by Schmidt (1907, pl. 2, fig. 9) resembles thepygidia previously assigned erroneously to plautini.

Hoplolichoides conicotuberculatus (NIESZKOWSKI,1859)

Fig. 2.1–191859 Lichas conico-tuberculata NIESZKOWSKI, p.

365, pl. 1, figs 7–10.1877 Lichas (Hoplolichas) conico-tuberculata NIESZ-

KOWSKI - Dames, p. 802, pl. 14, figs 2–6.1885 Lichas (Hoplolichas) conicotuberculata NIESZ-

KOWSKI - Schmidt, p. 82, pl. 3, figs 13–25.1901 Hoplolichas conicotuberculatus (NIESZKOWSKI)

- Gürich, pl. 20, fig. 14.1928 Lichas (Hoplolichas) conicotuberculatus NIESZ-

KOWSKI - Kummerow, p. 36, pl. 2, fig. 5.1936 Hoplolichoides conicotuberculatus

(NIEZSKOWSKI) - Phleger, p. 602, fig. 23.1937 Hoplolichoides conicotuberculatus (NIESZ-

KOWSKI) - Phleger, p. 1087.1939 Hoplolichas conicotuberculatus (NIESZKOWSKI)

- Warburg, p. 97, pl. 7, fig. 2.1957 Hoplolichas conicotuberculatus (NIESZKOWSKI)

- Tripp, p. 108, text-fig. 4O; p, 110, text-fig. 5C.1958 Hoplolichas conicotuberculatus (NIEZSKOWSKI)

- Tripp, p. 576.1971 Hoplolichas conicotuberculatus (NIESZKOWSKI)

- Neben and Krueger, pl. 34, figs 7–9.1988 Hoplolichas conicotuberculatus (NIESZKOWSKI)

- Thomas and Holloway, pl. 10, figs 193–197.Lectotype – Selected by Warburg (1939); cranidium

figured by Nieszkowski (1859, pl. 1, figs 7, 8), from theKukruse Stage (C2, lower Caradoc) at Erras (= Erra) orWannamois (= Vanamõisa), Estonia. The records of theInstitute of Geology, Tallinn Technical University, question-ably identify the lectotype as specimen no. Tr2099 (figuredThomas and Holloway, 1988, pl. 10, fig. 195). That appearsunlikely as the specimen does not match Nieszkowki’sillustration (e.g. the posterior borders and occipital ring,excluding the occipital spines, are shown in the illustrationbut are mostly covered by matrix in the specimen).

Material examined Five cranidia (MB T1809–T1811,T1814, T1815), two librigenae (MB T1821, T1822) andfour pygidia (MB T1812, T1813, T1819, T1820), all fromKukruse near Jõhvi, Estonia.

Diagnosis – Minimum width of median glabellar lobesituated level with intersection of axial and palpebralfurrows; L1a transverse, ovate. Pygidium with first twomarginal spines steeply inclined across their width, con-verging backwards; third spine subtriangular.

Description – Glabella approximately equal in widthacross occipital ring and L1a, expanding weakly forwardsfrom front of L1a to front of palpebral lobe, thereafter

narrowing at increasing rate to front of bullar lobe; width ofglabella at front of palpebral lobe 140% width across frontallobe and approximately equal to sagittal length (excludingoccipital ring) in palpebral view (with palpebral suturehorizontal). Occipital ring increasing strongly in length(exsag.) and height adaxially to base of occipital spines;median part of ring steep and slightly concave (sag.) in frontof spines (Fig. 2.1). Occipital spines stout, diverging back-wards at about 60° proximally, gently curved backwards inlateral and dorsal profiles. Large median occipital tuberclepresent in front of spines, and a pair of slightly smallertubercles close to posterior edge of ring behind L1a. Medianpart of occipital furrow shallow, transverse medially; lateralpart deeply incised and deflected backwards behind L1a.Glabella in front of occipital ring more convex sagittallythan transversely, in palpebral view descending forwards infront of δ-δ and overhanging medial part of anterior border;longitudinal furrow deepest anteriorly, meeting occipitalfurrow posteriorly in line (exsag.) with adaxial extremity ofL1a. L1a with two prominent tubercles situated slightlyanteromedially and posterolaterally of centre; furrow infront of L1a collinear with median part of occipital furrowbut shorter (exsag.) and deeper. L1b indistinctly defined byslight backward deflection of longitudinal furrow and byfaint transverse depression separating it from bullar lobe(Fig. 2.6); L1b with large tubercle adaxially. Bullar lobewidest at midlength in palpebral view, in front of midlengthpartially subdivided adaxially (most distinctly on internalmoulds) by very narrow (tr.), shallow, transverse S2; posi-tion of S2 commonly indicated on exterior of exoskeletononly by weak abaxial deflection and shallowing of longitu-dinal furrow (Fig. 2.10). Posterior half of median lobe withfairly regular arrangement of coarse, paired tubercles inthree rows; posterior two rows separated on internal mouldby weak transverse depression (S1) in line (exsag.) withfront of L1b (Fig. 2.6).

Axial furrow deep, narrow; preglabellar furrow beco-ming more sharply impressed adaxially. Anterior borderflattened (sag., exsag.), decreasing in length adaxially, itsmargin gently concave in outline abaxially. Fixigenal fieldsteeply declined in front of and behind palpebral lobe (Fig.2.1), overhanging posterior border adaxially in palpebralview. Posterior border increasing in height and length(exsag.) abaxially, its posterior edge curving gently back-wards; posterior border furrow deep, curving slightly for-wards abaxially. Palpebral lobe narrow (tr.), tapering morestrongly posteriorly than anteriorly, posterior edge situatedopposite front of L1b in palpebral view (Fig. 2.6, 10) andslightly farther from sagittal line than anterior edge; palpe-bral furrow strongly curved, shallow at midlength (exsag.);palpebral area inflated above level of palpebral lobe (Fig.2.1). Anterior branch of facial suture initially divergingslightly in front of palpebral lobe, thereafter convergingstrongly to lateral border furrow, diverging less stronglyforwards across anterior border; width α-α almost equal tomaximum width of glabella. Posterior branch of suture


Fig. 2. Hoplolichoides conicotuberculatus (NIESZKOWSKI, 1859), Kukruse Stage (C2, lower Caradoc), Kukruse, Estonia. 1, 5-6 MB T1810, cranidium,figured Dames (1877, pl. 14, fig. 3, 3a); lateral, oblique and palpebral views, × 1.75. 2-3 MB T1809, cranidium, figured Dames (1877, pl. 14, fig. 2); planand oblique views, × 2. 4, 8, 12-13 MB T1812, pygidium, figured Dames (1877, pl. 14, fig. 5); lateral, oblique, posterodorsal and dorsal views, × 2. 7. MBT1821, librigena, collected Dames 1877; dorsal view, × 2. 9, 14. MB T1822, librigena, collected Dames; dorsal and ventral views, × 2. 10-11 MB T1814,cranidium, collected Dames 1877; palpebral and oblique views, × 1.75. 15-16 MB T1820, pygidium, collected Dames 1876; posterodorsal and dorsal views,× 2. 17. MB T1815, fragmentary cranidium, collected Dames 1876; plan view, × 2. 18-19 MB T1813, pygidium, figured Dames (1877, pl. 14, fig. 6); dorsalview, × 2; marginal spines in dorsolateral view, × 3.Hoplolichoides conicotuberculatus (NIESZKOWSKI, 1859), Kukruse Stage (C2, Caradoc inférieur), Kukruse, Estonia. 1, 5-6 MB T1810, cranidium, Dames(1877, pl. 14, fig. 3, 3a); vues latérale, oblique et palpébrale, × 1.75. 2-3 MB T1809, cranidium, Dames (1877, pl. 14, fig. 2); vues plane et oblique, × 2.4, 8,12-13 MB T1812, pygidium, Dames (1877, pl. 14, fig. 5); vues latérale, oblique, postérodorsale et dorsale, × 2. 7. MB T1821, librigena, collecté parDames 1877; vue dorsale, × 2. 9, 14. MB T1822, librigena, collecté par Dames; vues dorsale et ventrale, × 2. 10-11 MB T1814, cranidium, collecté par Dames1877; vues palpébrale et oblique, × 1.75. 15-16 MB T1820, pygidium, collecté par Dames 1876; vues postérodorsale et dorsale, × 2. 17. MB T1815, fragmentde cranidium, collecté par Dames 1876; vue plane, × 2. 18-19 MB T1813, pygidium, figuré par Dames (1877, pl. 14, fig. 6); vue dorsale, × 2; vue dorsolatéraleet épine marginale, × 3.


curving strongly backwards abaxially, converging back-wards slightly across posterior half of posterior border.

Librigena with gently convex borders merging with baseof long, broad, flattened, sickle-shaped genal spine; lateralborder expands greatly in width posteriorly, outer marginwith shallow antennal notch anteromedially. Borders sepa-rated from more convex librigenal field by shallow borderfurrows that unite in a uniform curve (Schmidt, 1885, pl. 3,fig. 13b, 19); border furrows preserved in MB T1822 butmost of field missing (Fig. 2.9). Numerous small spinespresent along adaxial edge of genal spine. Librigenaldoublure broad, its inner edge corresponding approximatelyin position with border furrows.

Pygidium with maximum width across base of firstmarginal spine and level with pygidial midlength. Axisstrongly convex (tr.), tapering gently backwards, poorlydefined posteriorly; transverse row of prominent tuberclessituated at change of slope between flattened (sag.) crest ofaxis and steeply inclined postaxial region (Fig. 2.4). Articu-lating half ring short (sag., exsag.), of uniform length overmost of axial width. First axial ring only slightly longersagittally than articulating half ring, posterior edge withweak embayment medially to accommodate poorly definedpseudo-articulating half ring on second axial ring; secondring longer sagittally than first ring, decreasing slightly inlength laterally; second ring furrow very shallow medially.First and second rings each with a transverse row of sixtubercles; third ring defined only by alignment of tubercles.Furrow alongside postaxial region collinear with axialfurrow, becoming broad, shallow and poorly defined poste-riorly at intersection with border furrow. Pleural fieldconvex (tr.), steeply downturned abaxially; posterior pleuralbands more prominent than anterior bands, extending ontoborder distally. Each posterior band bearing a row of fourprominent tubercles; second tubercle (from adaxial end)very high and spinose, situated about half way betweenaxial and border furrows; most distal tubercle situated onborder. Pleural and interpleural furrows deep on pleuralfield, shallower on border where pleural furrows are de-flected laterally to reach margin between spines. Posteriorpart of pleural field with two or three prominent tuberclesarranged in a line directed slightly more strongly backwardsthan second interpleural furrow. First marginal spine termi-nating just behind transverse line through tip of notchbetween second and third spines; second spine broader andconverging more strongly backwards than first, terminatinglevel with tip of posteromedian spine; third spine terminat-ing in front of transverse line through tips of second andposteromedian spines; posteromedian spine becomingrounded in cross section distally. Border wider betweenthird spines than in front of third spines; border furrowshallow behind postaxial region, even shallower where itcrosses posterior pleural bands on first two segments.Doublure convex.

Dorsal surface of cranidium and pygidium with densesculpture of coarse tubercles together with superimposed

and interspersed granules; tubercles on occipital spinespoint towards distal ends of spines. Coarse tubercles lessabundant on librigena than on cranidium. Most of librigenaldoublure with two sets of terrace ridges: a low, widelyspaced set running subparallel to inner margin, and anintervening, very fine, anastomosing set; librigenal marginand outer part of doublure with coarser, closely spaced,subparallel terrace ridges. Coarse terrace ridges on pygidialdoublure extend onto dorsal surface along (mainly abaxial)edges of first two spines, where they run oblique to marginand bear a row of fine granules (Fig. 2.19).

Discussion – Schmidt (1885) recorded conicotubercula-tus in Estonia from the Kukruse Stage (C2) at Kuckers(= Kukruse), Erras (= Erra), Wannamois near Tolks (= Van-amõisa near Kohala), and Kawast (Kavastu near Rakvere),and from the uppermost part of the underlying Echino-sphaerites Limestone (Uhaku Stage, C1c) at Reval(= Tallinn). From the last locality he illustrated an incom-plete cephalon with several attached thoracic segments(Schmidt 1885, pl. 3, fig. 13a–c), the cephalon beingdepicted with a single median occipital spine rather thanpaired spines. However, the photograph of this specimen(Palaeontological Institute, Moscow, no. 4248/121) pro-vided by Bruton et al. in their internet catalogue ofSchmidt’s trilobites (see above), shows that the appearanceof a single occipital spine is apparently caused by breakage,and that paired spines were probably originally present.Warburg (1939) considered that this specimen may belongto her species Hoplolichoides curvifrons, based on speci-mens from an erratic of early Caradoc age from Sweden, butthe specimen seems to agree in most features with otherspecimens of conicotuberculatus from Estonia. OutsideEstonia, conicotuberculatus has been recorded from Swe-den (island of Björkön, Uppland), southern Norway, andfrom glacial erratics in northern Germany (Kummerow,1928; Warburg, 1939; Neben and Krueger, 1971).

The oldest species of the genus is Hoplolichoides furcifer(SCHMIDT, 1885), from the Aseri-Uhaku Stages (C1,middle Llanvirn-lowermost Caradoc) of Estonia and Russia(St Petersburg district). It differs from conicotuberculatus inhaving a broader bullar lobe; the minimum width of themedian lobe is situated farther back, behind a transverse linethrough the intersection of the axial and palpebral furrows;the longitudinal furrow is more strongly curved and isshallower posteriorly behind S1; and L1a is subtriangularrather than ovate. In the pygidium of furcifer, incorrectlyassigned to Hoplolichas plautini by Schmidt (1885) (seeabove), the first two marginal spines are broader than inconicotuberculatus, are less inclined across their width, anddo not converge backwards. Hoplolichoides curvifrons(WARBURG, 1939) is most readily distinguishable fromconicotuberculatus by the third pair of pygidial spines thatare rounded and lobate rather than subtriangular.

Subfamily PLATYLICHINAE Phleger, 1936Diagnosis – Axial furrow effaced adjacent to L1b, which

merges abaxially with fixigenal field. Bullar lobe circum


scribed, bounded posterolaterally by S1; in some genera,bullar lobe expanded backwards to reach or almost reachL1a, displacing adaxial part of L1b; longitudinal furrowinvariably extends to occipital furrow or L1a. Hypostomewith middle body narrower across posterior lobe than acrossanterior lobe; shoulder situated opposite middle furrow orposterior lobe of middle body. Pygidium with 2–3 pairs ofpleural furrows and three pairs of flattened marginal spines;anterior and posterior bands usually flattened.

Genera and subgenera included – Platylichas (Platyli-chas) GÜRICH, 1901; P. (Rontrippia) THOMAS & HOL-LOWAY, 1988; Allolichas KRUEGER, 1992; Autoloxoli-chas PHLEGER, 1936; Metalichas REED, 1902.

Remarks – Thomas and Holloway (1988, fig. 362, p.249) recognized the close affinities between Platylichas andAutoloxolichas, a pair of genera to which Allolichas is alsorelated. It is appropriate to use the Subfamily Platylichinaeto reflect this grouping, to which we also assign the poorlyknown Metalichas (see Thomas and Holloway, 1988). Thissubfamily was recognised by Hupé (1953) and Balashova(1960), but Tripp (1957, 1959) and Thomas and Holloway(1988) implicitly placed it in synonymy with the Homoli-chinae by including Platylichas in the latter subfamily.Members of the Platylichinae differ from the Homolichinaein having the axial furrow effaced adjacent to L1b, whichconsequently is fused with the fixigenal field instead of withthe bullar lobe to form a composite lobe. The stronglyoblique furrow bounding the bullar lobe posterolaterally inthe Platylichinae is not the axial furrow but S1, which meetsthe longitudinal furrow posteriorly and joins the axialfurrow anteriorly near the front of the palpebral lobe (Fig.1.6–8). The homology of the glabellar lobes and furrows isfairly easily determined in Platylichas and Metalichas,which have the bullar lobe relatively widely separated fromL1a. In Allolichas and Autoloxolichas, however, the bullarlobe has expanded backwards to reach or almost reach L1a,thus assuming more of the appearance of the compositelateral lobe of the Homolichinae. In some specimens ofAllolichas and Autoloxolichas the axial furrow is weaklydiscernible adjacent to L1b, running almost parallel with thesagittal axis, showing that the enlarged bullar lobe in thesegenera has displaced L1b, which is very small and subtri-angular in outline. Given the similarities in gross glabellarmorphology shared by Platylichas and the lichakephalidLichakephalus, the Platylichinae appear less derived in theirglabellar structure than the Homolichinae.

Thomas and Holloway (1988) regarded the hypostomalcharacters as important in characterizing their concept of aunited Homolichinae + Platylichinae, but those shared simi-larities are now regarded as primitive for lichids as a whole(see remarks on Homolichinae). Not all platylichine hypos-tomes retain the primitive condition of being longer thanwide, some being more elongated (e.g. Allolichas, seebelow; some species of Platylichas, see Thomas and Hol-loway, 1988, pp. 184, 213, pl. 9, fig. 173).

Genus Allolichas KRUEGER, 1992

Type species – Allolichas longispinus KRUEGER, 1992,p. 271, from glacial erratics of the Backsteinkalk (upperKukruse Stage, C2�, lower Caradoc) of north-eastern Ger-many; original designation.

Other species – A. crescenticus (REED, 1935) (= Lichas(Platylichas) vicinus REED, 1935; see Morris 1988, p.179); A. glenos (WHITTINGTON, 1962); A. halli (FOER-STE, 1888); A. laxatus (MCCOY, 1846); A. micus (ANTSY-GIN, 1973); A. noctua (PRICE, 1980); A. nodulosus (MC-COY, 1851); A. thraivensis (REED, 1935); A.? gracile(KUMMEROW, 1928); A.? inconsuetus (RAYMOND,1925); A.? miseneri (FOERSTE, 1920).

Stratigraphical and geographical range – Arenig,Urals; Caradoc-Ashgill, North America (Indiana,Ohio, ?New York), Ireland, England, Scotland, Wales, Nor-way, Sweden, northern Germany (erratics), Estonia, ArcticRussia (Vaigach Island and Pai-Khoi).

Diagnosis – Platylichine with gently convex (sag., tr.)cranidium, glabella not overhanging anteriorly; anteriorborder flattened, commonly expanding weakly adaxially,comprising about 10% sagittal cranidial length. Longitudi-nal furrow meeting inner end of S1 posteriorly in acuteangle at adaxial extremity of L1a. Long axis of bullar lobealmost parallel to sagittal line; minimum width of medianlobe situated level with midlength (exsag.) of bullar lobe,less than width of bullar lobe measured across sametransverse line. Hypostome approximately as wide acrossshoulders as long (sag.), with subcircular middle body.Pygidium with axis comprising half sagittal length or more;three or four axial rings, last ring furrow commonlyincomplete medially; postaxial band narrow. Pleurae withthree pairs of pleural furrows and three pairs of long andslender marginal spines, first two pleural furrows runningdistally onto bases of marginal spines; gently convex borderpresent posteriorly, bounded by distinct border furrowjoining furrow alongside postaxial band with last pleuraland interpleural furrows.

Remarks – Krueger (1992) included in Allolichas onlythe type species, A. longispinus, the long median occipitalspine of which he considered to be the most importantdiagnostic character of the genus. In other characters, suchas the intersection of the longitudinal furrow and S1 in anacute angle at the adaxial extremity of L1a, the narrownessof the median lobe between the bullar lobes, the weaklyadaxially expanding anterior border, the long (sag.) pygidialaxis and narrow postaxial band, the long and slenderpygidial marginal spines, and the gently convex border onthe posterior part of the pygidium, longispinus resemblesspecies such as ‘Lichas’ laxatus MCCOY, 1846 (see Dean,1963, p. 235, pl. 43, figs 1–2, 5, 8–12), ‘Trochurus’nodulosus MCCOY, 1851 (see Thomas and Holloway,1988, pl. 9, figs 185, 188–192), and ‘Platylichas’ noctuaPRICE, 1980. Such species, which were included in Au-toloxolichas by Thomas and Holloway (1988), lack the longoccipital spine of longispinus, though a small median spineor tubercle may be present (e.g. Warburg, 1939, pl. 12, fig.


8a; Thomas and Holloway, 1988, pl. 9, figs 188–190).However, we do not consider the presence of cranidialspines to be especially important taxonomically in Lichida(Thomas and Holloway, 1988). We therefore expand theconcept of Allolichas to include all the species that wepreviously assigned to Autoloxolichas, except for the typespecies of the latter. See the discussion of Autoloxolichas forcomparison of that genus with Allolichas.

The hypostome of Allolichas is distinctive in its ratherelongated outline and subcircular middle body (see Whit-tington, 1962, pl. 7, figs 9, 10; Dean, 1963, pl. 43, fig. 12;Price, 1980, pl. 113, fig. 2; Krueger, 1992, pl. 1, fig. 3).

Genus Autoloxolichas PHLEGER, 1936Type species –Lichas St. Mathiae SCHMIDT, 1885, p.

115, from the Jõhvi (D1) and Keila (D2) stages (middle–up-per Caradoc) of Estonia; original designation.

Other species – None known.Diagnosis – Platylichine with gently convex (sag., ex-

sag., tr.) cranidium; anterior border short (less than halfsagittal length of occipital ring), upper surface slopingforward at almost same angle as front of glabella, anteriorsurface vertical. Bullar lobe ovate in outline, circumscribedby axial and longitudinal furrows and S1, separated fromL1a posteriorly by very short (exsag.), slightly depressedregion; long axis of bullar lobe oriented at about 30° tosagittal line Minimum width of median lobe situated wellbehind midlength (exsag.) of bullar lobe, less than width ofbullar lobe measured across same transverse line.Cranidium with sculpture of dense granules grading intoterrace ridges on front of glabella.

Remarks – Öpik (1937) considered that the pygidiaassigned to sanctamathiae by Schmidt are not conspecificwith the cranidia. Sculptural differences (granules gradinganteriorly into undulating ridges on the cranidia; zigzagscaly ridges on the pygidium) lend some support to thisview. Because of the uncertainty in the assignment of thepygidia, the generic diagnosis is based on cranidial charac-ters alone.

Autoloxolichas is here restricted to the type species, theother species included in the genus by Thomas and Hollo-way (1988) being placed in Allolichas. Allolichas is verysimilar to Autoloxolichas in the development of thecranidial lobes and furrows but differs in having thelongitudinal furrow extending farther posteriorly, reachingthe adaxial extremity of L1a instead of uniting with theinner end of S1 a short distance in front of L1a; the bullarlobe is acute posteriorly rather than rounded, and is lessobliquely oriented, its long axis lying approximately parallelto the sagittal line; the minimum width of the median lobeis situated farther forwards, level with the midlength (ex-sag.) of the bullar lobe; and the anterior border is horizontalrather than sloping forwards, and commonly lengthensslightly medially. Pygidia of Allolichas are not similar tothose assigned to Autoloxolichas sanctamathiae by Schmidt(1885).

Autoloxolichas sanctamathiae (SCHMIDT, 1885)

Fig. 3.1–101885 Lichas St. Mathiae SCHMIDT, p. 115, pl. 5, figs

11–16.1936 Autoloxolichas st.-mathiae (SCHMIDT) - Phleger,

fig. 78.1937 Platylichas st. mathiae FR. SCHMIDT - Öpik, p.

57, pl. 22, fig. 2, text-fig. 15.1957 Platylichas sanctaemathiasae (SCHMIDT) - Tripp,

p. 116.1958 Platylichas sanctaemathiasae (SCHMIDT, 1885) -

Tripp, p. 576.1988 Autoloxolichas sanctamathiae (SCHMIDT, 1885) -

Thomas and Holloway, p. 206, pl. 10, figs 212, 213.in press Autoloxolichas sanctamathiae (SCHMIDT,

1885) - Whittington, fig. 4.1–4.5.Type material – Lectotype designated herein, cranidium

CNIGR 92/11101, figured Schmidt (1885, pl. 5, fig. 13),Fig. 3.6 herein; from the Keila (D2) stage (middle–upperCaradoc) of Kegel (= Keila), Estonia. This designation ismade in order to clarify the application of the species name,as the pygidia associated with the cranidia by Schmidt(1885) may not be conspecific. Paralectotypes includecranidia CNIGR 90/11101 (figured Schmidt, 1885, pl. 5, fig.11; Fig. 3.5 herein) and CNIGR 91/11101 (Schmidt, 1885,pl. 5, fig. 12; Fig. 3.8 herein); hypostome CNIGR 93/11101(Schmidt, 1885, pl. 5, fig. 14; Fig. 3.4 herein); and pygidiaCNIGR 94/11101 (Schmidt, 1885, pl. 5, fig. 15a, b; Fig. 3.9herein) and CNIGR 95/11101 (Schmidt 1885, pl. 5, fig. 16;Fig. 3.7, 10 herein). Additional syntypes mentioned bySchmidt (1885) but not figured by him have not been traced.

Other material – Cranidia GIE Tr2254 (figured Öpik1937, pl. 22, fig. 2; Thomas and Holloway, 1988, pl. 10, fig.212), GIE Tr19546 (figured Thomas and Holloway, 1988,pl. 10, fig. 213), and RM Ar54838a–b (Fig. 3.1–3).

Description – Cranidium approximately twice as wide atposterior margin as long (sag.); glabella widest across bullarlobes (level with intersection of axial and palpebral furrows)and occipital ring, slightly narrower across frontal lobe andL1a, narrowest across L1b (level with posterior end ofbullar lobe; see below). Occipital ring with small, weakmedian swelling close to posterior margin. L1a, bullar andfrontomedian lobes with slight independent convexity. L1alenticular, almost as wide (tr.) as median part of occipitalfurrow. L1b generally not defined abaxially, but in somespecimens (e.g. Thomas and Holloway, 1988, pl. 10, fig.213, left side) axial furrow faintly visible in front of L1a,running almost parallel to sagittal line from a point levelwith 33% distance between abaxial and adaxial extremitiesof L1a, meeting outer end of S1 just behind intersection ofaxial and palpebral furrows. S1 directed posteromedially atabout 40° to sagittal line, not clearly differentiated in depthor course from axial furrow immediately in front of S1,shallowing posteriorly towards junction with longitudinalfurrow. Bullar lobe ovoid, more pointed posteriorly thananteriorly. Longitudinal furrow meeting axial furrow atabout 25% glabellar length (sag.), directed slightly forwards


before curving backwards in a broad arc to join S1;narrowest part of median lobe situated at about 60%glabellar length (sag.) from anterior. Palpebral lobe situatedless than its own length from posterior cranidial margin,sloping abaxially almost at same angle as fixigena, lyingfarther from sagittal line posteriorly than anteriorly, poste-rior edge opposite posterior edge of bullar lobe; palpebralfurrow much more weakly curved than palpebral margin,meeting axial furrow level with cranidial midlength (sag.).Posterior branch of facial suture sigmoidal, divergingstrongly backwards; anterior branch running parallel to

axial and preglabellar furrows. Posterior border weaklyconvex (exsag.), expanding strongly abaxially; posteriorborder furrow directed obliquely forwards abaxially. Ante-rior border of uniform length (sag., exsag.). approximately50% sagittal length of occipital ring; anterior border furrowmuch weaker on external surface than on internal mould.Cranidium with sculpture of dense granules of two sizes, onlarger specimens merging into undulating transverse ridgeson frontal lobe of glabella.

Hypostome with sagittal length 80% width across shoul-ders, latter situated just behind midlength (sag.). Middle

Fig. 3. Autoloxolichas sanctamathiae (SCHMIDT, 1885), Keila Stage (D2, middle-upper Caradoc), Estonia. 1-3. RM Ar54838a, exfoliated cranidium,collected V. Jaanusson 1941; dorsal, oblique and lateral views, × 2.25; Pääsküla. 4 CNIGR 93/11101, mostly exfoliated hypostome, figured Schmidt (1885,pl. 5, fig. 14); ventral view, × 2; St Mathias (= Madise). 5. CNIGR 90/11101, partly exfoliated cranidium, figured Schmidt (1885, pl. 5, fig. 11); dorsal view,× 1.75; Madise. 6. CNIGR 92/11101, cranidium, lectotype, figured Schmidt (1885, pl. 5, fig. 13a, b); dorsal view, × 3; Keila. 7, 10. CNIGR 95/11101,exfoliated pygidium, figured Schmidt (1885, pl. 5, fig. 16); posterior and dorsal views, × 1.75; Haljal (= Haljala) or Friedrichshof (= Saue). 8. CNIGR91/11101, cranidium, figured Schmidt (1885, pl. 5, fig. 12); dorsal view, × 4; Spitham (= Põõsaspea). 9. CNIGR 94/11101, partly exfoliated pygidium, figuredSchmidt (1885, pl. 5, fig. 15a, b); dorsal view, × 3.5; Madise. All photographs except Fig. 6 are of plaster replicas.Autoloxolichas sanctamathiae (SCHMIDT, 1885), Keila Stage (D2, Caradoc moyen-supérieur), Estonia. 1-3. RM Ar54838a, cranidium esfolié, collecté parV. Jaanusson 1941; vues dorsale, oblique et latérale, × 2.25; Pääsküla. 4 CNIGR 93/11101, hypostome presque entièrement exfolié, figuré par Schmidt (1885,pl. 5, fig. 14); vue ventrale, × 2; St Mathias (= Madise). 5. CNIGR 90/11101, cranidium partiellement exfolié, figuré par Schmidt (1885, pl. 5, fig. 11); vuedorsale, × 1.75; Madise. 6. CNIGR 92/11101, cranidium, lectotype, figuré par Schmidt (1885, pl. 5, fig. 13a, b); vue dorsale, × 3; Keila. 7, 10. CNIGR95/11101, pygidium exfolié, figuré par Schmidt (1885, pl. 5, fig. 16); vues postérieure et dorsale, x 1.75; Haljal (= Haljala) ou Friedrichshof (= Saue). 8.CNIGR 91/11101, cranidium, figuré par Schmidt (1885, pl. 5, fig. 12); vue dorsale, × 4; Spitham (= Põõsaspea). 9. CNIGR 94/11101 pygidium partiellementexfolié, figuré par Schmidt (1885, pl. 5, fig. 15a, b); vue dorsale, × 3.5; Madise.


body gently convex transversely and weakly convex sagit-tally; anterior lobe comprising about 75% sagittal length ofmiddle body, subelliptical in outline, widest at midlength(sag.); middle furrow situated opposite shoulder, deep,transverse, abruptly dying out about half way betweenlateral border furrow and sagittal line; posterior lobe 70%maximum width of anterior lobe, with elongated maculaeextending posteromedially from middle furrow. Lateralborder convex (tr.) behind shoulder, outer edge with slightembayment opposite posterior border furrow; lateral borderfurrow shallower and broader opposite posterior lobe ofmiddle body than opposite anterior lobe, even shallowerbehind intersection with posterior border furrow, where it isdeflected outwards slightly before curving inwards anddying out. Posterior border slightly convex (sag., exsag.),highest anteriorly, posterior margin with broad, roundedmedian embayment; posterior border furrow deep. Adheringfragment of exoskeleton with terrace ridges on anteriorwing and around margin of shoulder, and with weak pits onborder opposite shoulder; internal mould with weakwrinkles on outer part of lateral border posteriorly, replacedby shallow dimples (swellings on interior of exoskeleton)adaxially on lateral and posterior borders.

Pygidium (specimens possibly incorrectly assigned tothis species) with maximum width situated well in front ofmidlength (sag.) and level with posterior end of axis. Axisconical, approximately 40% maximum pygidial width ante-riorly, poorly defined posteriorly; in transverse profile, axisstrongly convex with maximum curvature along sagittalline, in lateral profile gradually decreasing in height poste-riorly over most of its length but subsiding more abruptlybehind transverse line through adaxial ends of secondinterpleural furrows. First axial ring with slight relief,longest (sag., exsag.) distally and midway between axialfurrow and sagittal line, defined by continuous ring furrow;second ring much weaker, ring furrow dying out medially;very faint trace of third ring furrow present abaxially onlarger pygidium. Pleurae weakly convex (tr.), sloping gentlyabaxially; lateral margin curving strongly adaxially fromregion of maximum pygidial width to tip of first marginalspine. First spine very short, broad, separated from secondspine by narrow incision; shape of second and third (ifpresent) spines unknown. First two pleural furrows notrunning onto marginal spines distally but meeting outer endof succeeding interpleural furrow at pygidial margin be-tween spines; first pleural furrow more strongly curved thansecond; third pleural furrow not impressed. First interpleuralfurrow weakly concave backwards, almost straight; secondconvex backward. Postaxial band funnel-shaped, narrowingbackwards more strongly in front of transverse line throughdistal ends of first pleural and interpleural furrows thanbehind this line. Doublure very wide, extending forwards insagittal line to posterior end of axis, having shallow radialfurrows abaxially beneath pleural furrows. Dorsal surface ofpygidium with scaly sculpture, on pleurae having appea-rance of discontinuous, serrated terrace ridges aligned more

or les stransversely; doublure with widely spaced, continu-ous terrace ridges concentric with margins.

Remarks – The smallest cranidium, CNIGR 91/11101(Fig. 3.8), differs from the larger ones in lacking any traceof transverse ridges on the front of the glabella, all pre-served areas of exoskeleton (which include part, but not theanteriormost part, of the frontal lobe) having a densesculpture of granules of two sizes. On the large cranidiumRM Ar54838a-b the exoskeleton adheres to the externalmould so that the exterior surface is not visible, but theinternal mould shows traces of the undulating, transverseridges on the frontal lobe (Fig. 3.1–3) The illustration of thelargest cranidium, CNIGR 90/11101, given by Schmidt(1885, pl. 5, fig. 11) shows transverse ridges on the fragmentof exoskeleton adhering to the frontal lobe, but no trace ofsculpture now remains on the specimen itself, the surface ofthe exoskeletal fragment having been obliterated by scra-ping. This specimen is also less complete on the left sidethan shown in Schmidt’s illustration, most of the fixigena,the anterior border, and the lateral part of the occipital ringbeing missing. These differences may be due to restorationin the illustration or to later damage to the specimen.

Subfamily TROCHURINAE Phleger, 1936

Genus Akantharges PHLEGER, 1936

Type species – Lichas Gourdoni BARROIS, 1886, p.126, from the Eifelian of the central Pyrenees, France;original designation.

Other species – A. erbeni (MEISCHNER, 1965); A. sp.of Thomas and Holloway (1988).

Stratigraphical and geographical range – Middle De-vonian (Eifelian–Givetian); France (Pyrenees), Germany(Rheinisches Schiefergebirge), Morocco.

Diagnosis – Trochurine with strongly convex (sag., ex-sag.) glabella not overhanging anterior border; longitudinalfurrow very shallow anteriorly and behind S1; L1 depressedmedially; L1a not defined. Palpebral lobe small, situatedlow on cheek rather far from glabella; anterior and posteriorsections of facial suture collinear. Posterolateral cranidiallobe bearing long (exsag.) ridge curving forwards andbackwards abaxially, and bounded posteriorly by distinctfurrow; ridge may interrupt posterior border furrow distally.Subgenal notch may be well developed; genal spine longand blade-like. Pygidium with three pairs of long, slendermarginal spines that are rounded in cross-section. Axiscomprising 66% sagittal length of pygidium or more, withone or two prominent axial rings and at least eight addi-tional, poorly defined rings; postaxial ridge indistinct orabsent. Anterior pleural bands slightly inflated on segments1–3, on third segment running subparallel with sagittal axisanteriorly and converging posteriorly; pleural and interpleu-ral furrows shallow; border absent.

Remarks – A distinctive feature of Akantharges is therounded (exsag.) ridge curving forwards and backwards


abaxially across the posterolateral cranidial lobe. This ridge,which bears a number of large tubercles, is boundedposteriorly by a rather sharp furrow originating near theouter end of the occipital furrow and curving forwardsinitially and then backwards abaxially towards the posteriorborder furrow. The ridge and furrow are well developed inthe type species, A. gourdoni, and in the unnamed speciesfrom Morocco (see Thomas and Holloway, 1988, pl. 14, figs300, 303, 305), but they are weaker in A. erbeni (see Basse,1998, pl. 15, fig. 26a–b; Fig. 4.6, 8, 10–11 herein). A similarridge and furrow are present also in Ceratarges, as noted byThomas and Holloway (1988), but are not known in otherlichids. In Ceratarges the ridge carries the eye (situated atthe end of a long stalk) and, lateral to the base of the eyestalk, the posterior branch of the facial suture, but inAkantharges the eye and the posterior branch of the facialsuture have migrated laterally so that they are no longersituated on the ridge.

The relationships of many genus-group taxa within theTrochurinae are unclear. This is particularly so for theDevonian forms, which are commonly both distinctive andimperfectly known. Based on glabellar and pygidial fea-tures, and on the supposed absence from both of a subgenalnotch, Thomas and Holloway (1988, p. 252, fig. 365)tentatively suggested that Akantharges might have beenderived from Richterarges. It is now known that a subgenalnotch may be present in Akantharges. Thomas and Hollo-way also suggested a possible derivation of Ceratarges, andother genera with deep subgenal notches and mediallyshortened L1, from Acanthopyge (Lobopyge).

Adrain (1994) adopted a restricted definition of therelated Richterarges, assigning some species formerly ac-commodated there to his Borealarges. He (p. 1084) reco-gnised a Richterarges/Borealarges/Terranovia clade withinthe Trochurinae but, in discussion, identified no particularpoints of similarity suggesting a close relationship betweenCeratarges and this clade. The common possession of thecurved ridge and furrow on the posterolateral cranidial lobemay indicate that Akantharges and Ceratarges are closelyrelated, and were derived from a common ancestor.

The pygidium of A. gourdoni is not well known due todeformation of the specimens, and consequently Thomasand Holloway (1988) did not include pygidial characters intheir generic diagnosis. Pygidial characters in the reviseddiagnosis given above are based mainly on the somewhatbetter preserved specimens of A. erbeni. In overall propor-tions, and in the three pairs of long, slender marginal spinesthat are rounded in cross section, the pygidium ofAkantharges resembles that of Acanthopyge (Acanthopyge),but the latter is distinguished mainly by the presence of adistinct postaxial band bordered laterally by furrows. If theabove suggestion of a common ancestry for Akanthargesand Ceratarges is correct, then A. (Acanthopyge) is lessclosely related to Akantharges.

Akantharges erbeni (MEISCHNER, 1965)

Fig. 4.1–14

1965 Acanthopyge erbeni MEISCHNER, p. 124, pl. 1,figs 1–7, text–figs 1–6.

1998 Akantharges? cf. erbeni (MEISCHNER, 1965) -Basse, pl. 15, fig. 26a–b.

?1998 Akantharges? gr. erbeni (MEISCHNER, 1965) -Basse, p. 78, pl. 11, fig. 8.

Holotype - Internal and external moulds of cranidium Gö548–1; figured Meischner (1965, pl. 1, fig. 1a–c), Fig.4.1–2, 5 herein; from Givetian phyllites near Gellershausen,Kellerwald, Germany.

Diagnosis – L1 shorter (sag.) than occipital ring; medianand bullar lobes without paired arrangement of coarsetubercles; curved ridge on posterolateral cranidial loberelatively weak, not interrupting posterior border furrowdistally; subgenal notch well developed.

Remarks – Meischner (1965) gave an exhaustive de-scription of A. erbeni, as well as providing reconstructionsof the cephalon and pygidium. The specimens have all beenflattened tectonically to some extent, and some have alsobeen sheared, affecting the convexity of the exoskeleton tovarying degrees. From examination of a range of specimensit is apparent that Meischner’s (1965, fig. 2e) depiction ofthe bullar and posterolateral cranidial lobes as subconical,posterolaterally curving projections represents an artefact ofdeformation rather than the original appearance of theselobes. These lobes were probably originally evenly rounded(exsag.).

Comparison with A. gourdoni is hindered by the strongdeformation of the material of that species, but obviousdifferences from A. erbeni include: L1 is longer (sagittallength greater than that of the occipital ring); the curvedridge on the posterolateral cranidial lobe is more distinctand interrupts the posterior border furrow distally; thesubgenal notch is much shallower; and the pygidial axis islonger (about 85% of the sagittal length of the pygidium).The well preserved cranidium of Akantharges sp. fromMorocco (Thomas and Holloway, 1988, pl. 14, figs299–300, 303) differs from A. erbeni in that L1 is longer(sag.); the curved ridge on the posterolateral cranidial lobeis more distinct and interrupts the posterior border furrowdistally; the subgenal notch is non-existent; there are promi-nent paired tubercles on the median glabellar and bullarlobes; and there are three very coarse tubercles in a row onthe curved ridge on the posterolateral cranidial lobe.

The cranidium from Usseln, Germany, figured by Basse(1998, pl. 15, fig. 26a–b) as Akantharges? cf. erbeni agreeswith the types in all observable characters and is undoub-tedly conspecific, but worthwhile comparisons cannot bemade with the incomplete pygidium figured by Basse (1998,pl. 11, fig. 8) as Akantharges? gr. erbeni.


Fig. 4. Akantharges erbeni (MEISCHNER, 1965), Givetian phyllites near Gellershausen, Kellerwald, Germany. 1-2, 5. Gö548-1 cranidium, holotype, figuredMeischner (1965, pl. 1, fig. 1a–c); latex cast of external mould, dorsal view, and internal mould, dorsal and oblique views, × 3.25. 3, 11. Gö548-69 cranidium;latex cast of external mould and internal mould, dorsal views × 3.25. 4. Gö548-7 librigena; latex cast of external mould, ventral view, × 3.5. 6. Gö548-137cranidium; latex cast of external mould, dorsal view, × 3.25. 7. Gö548-237 hypostome; latex cast of external mould, ventral view, × 4.5. 8. Gö548-76cranidium; latex cast of external mould, × 3. 9. Gö548-134 cranidium; latex cast of external mould, dorsal view, × 3. 10. Gö548-24 cranidium; latex castof external mould, dorsal view, × 3.25. 12. Gö548-12 pygidium, figured Meischner (1965, pl. 1, fig. 6; left and right reversed in photograph); natural mould,dorsal view, × 2. 13. Gö548-74, pygidium; latex cast of external mould, dorsal view, × 1.75. 14. Gö548-278 pygidium; latex cast of natural mould, ventralview, × 2.Akantharges erbeni (MEISCHNER 1965), phyllites du Givétien près de Gellershausen, Kellerwald, Germany. 1-2, 5. Gö548-1 cranidium, holotype, figurépar Meischner(1965, pl. 1, fig. 1a–c); moulage en latex d’un moule externe, vue dorsale et moule interne, vues dorsale et oblique, × 3.25. 3, 11. Gö548-69cranidium; moulage en latex d’un moule externe et d’un moule interne, vue dorsale, × 3.25. 4. Gö548-7 librigena; moulage en latex d’un moule externe, vuedorsale, × 3.5. 6. Gö548-137 cranidium; moulage en latex d’un moule externe, vue ventrale, × 3.25. 7. Gö548-237 hypostome; moulage en latex d’un mouleexterne, vue ventrale, × 4.5. 8. Gö548-76 cranidium; moulage en latex d’un moule externe, × 3. 9. Gö548-134 cranidium; moulage en latex d’un mouleexterne, vue dorsale, × 3. 10. Gö548-24 cranidium; moulage en latex d’un moule externe, vue dorsale, × 3.25. 12. Gö548-12 pygidium, figuré parMeischner(1965, pl. 1, fig. 6; photographies gauche et droite inversées); moule naturel, vue dorsale, × 2. 13. Gö548-74 pygidium; moulage en latex d’unmoule externe, vue dorsale, × 1.75. 14. Gö548-278 pygidium; moulage en latex d’un moule naturel, vue ventrale, × 2.


. Biblio non appelée

Tripp, 1958

Acknowledgements

We are grateful to H. Jahnke (Georg-August-Universität,Göttingen) and E. Pietrzeniuk (Museum für Naturkunde derHumboldt Universität, Berlin) for granting access to collec-tions and arranging the loan of material; J. Bergström(Naturhistoriska Riksmuseet, Stockholm) and I.M.Kolobova (formerly of VSEGEI, St Petersburg) for provid-ing latex moulds of specimens; and D.L. Bruton (Paleon-tologisk Museum, Oslo) for providing the image of thelectotype of Autoloxolichas sanctamathiae in Fig. 3.6. DJHgratefully acknowledges a grant from the Deutscher Aka-demischer Austauschdienst, enabling him to travel to Ger-many in 1993, and thanks Hans-Hartmut and Ingrid Kruegerfor their kind hospitality in Berlin. We thank E.N.K.Clarkson and R. Feist for their constructive reviews of themanuscript.

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Hoplolichoides Allolichas Autoloxolichas and Akantharges And the Classification of Lichid Trilobites

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