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BULLETIN DE L INSTITUT ROYAL DES SCIENCES NATURELLES DE BELGIQUE BULLETIN VAN HET KONINKLIJK BELGISCH INSTITUUT VOOR NATUURWETENSCHAPPEN

BIOLOGIE 75 5 20 200i BIOLOGIE 75 5 20 2005

Contributions to the odontological study of living Chondrichthyes. 2. The genus Oxynotus RAFINESQUE, 1810

by J HERMAN, M HOVESTADT-EULER & D C HOVESTADT

Abstract The tooth morphologv of three ot the four species ot the genus Ownotus is described and partly illustrated by SEM photo­graphs An interspecific diagnosis re\eals the tooth morphological differences between the species O hitiiuensis O ccntuna and O paiadoxus

Kev words: Odontology - Chondrichth\es - Squalitormes -Oxvnotidae - Ownotus - Tooth morphologv

Resumé La morphologic dentairc de trois dcs quatre especes du genre Ownotus est detrite et liguree partiellement a 1 aide dc cli­ches MEB Une diagnose interspecifique precise les dilterences morphologiques dcntaires obser\ees entre les especes O biuniensis O centiina cl O paiadoxus

Mots-cles: Odontologie - Chondrichthyes - Squahformes -Oxynotidac - Oxxnotus - Morphologic dentairc

Kur^fassung: Die Zahnmoiphologie von dici von der vicr Arten der Gattung Ownotus werden bcschricbcn und teilweise illustnert mit REM Photos Eine interspezitische Diagnose zcigt die /ahn-moiphologische Unterschicdc zwischen den Arten O biuniensis O centiuia und O paiadoxus

Schlusselworter: Odontologie - Chondrichthyes -Oxynotidac - Oxxnotus - Zahnmorphologic

Introduction

Squalitormes -

With the exception of O centiina the tooth morphology of the taxa of the genus OxMiotus is pooily known For this study tooth material was available of O hruniensis O centnna and O paradoxus Due to lacking tooth samples of O caiihbaeiis this species could not be incorporated in this study The tooth morphology of O biuniensis and O paradoxus will be described and illustrated O centnna, which was described and illustrated by HERMAN, HovESTADT-EULER & HovESTADT (1989), will be used here and more information, as well as more illustrations are pro vided An interspecific differential diagnosis reveals their tooth morphological differences For the terminology used here, see HERMAN, HOVESTADT-EULER and HOVESTADT 1989

Material

For this study , lollowing material was available Oxxnotus hiuniensis Iwo males, Oxxnotus centnna 13 males and 16 Icmalcs, Oxxnotus paiadoxus 5 males and 3 females

Oxynotus RAFINESQUE, 1810

The genus O \ A «of «5 comprises loui species O biuniensis (OGILBY, 1893) , O canbbaeiis, CERVIGON 1961, the type species O centnna (LINNAEUS, 1758) and O paiadoxus FRADE 1929

Oxynotus bruniensis (OGILBY, 1893) OGILBY J D , 1893 Centi ma bi un tens is Records of the

Austialian Museum Sidney 2(5) 62-63 Textplates 1,2, plates 1 to 3

For the first schematic illustration ol upper and lower teeth see GARRICK J A F , 1960 Studies on New Zealand Elasmobranchu XI Squaloids ol the genera Deania Ctmopteius, Oxxnotus and Dalatias in New Zealand waters Transaction of the royal Society of New, Zealand Wellington 88(3) 519-557 6 figs For a second one, with correct illustrations of outer faces of one upper tooth and one lower tooth see LAST PR & STEVENS J D 1994 Sharks and Raxs of Austialia CSIRO division of Fisheries Sidney 513p,84pl (of p 105)

This species shows a strong dignathic heterodonty and a weak monognathic heterodonty The root is always anaulacorhizid The dimensions of the lower teeth are subcentrimetrical, those of the upper teeth plurimilimetrical in size

UPPER JAW

The teeth arc compressed, having a more or less vertically elongated crown and root

6 J HERMAN M HOVESTADT-EULER & D C HOVESTADT

lextplate 1 • Oxynotus hrunieiisis (OGILBY, 1893). Male 560mm 11, caught off Wollongon Ncw-South Wales Australia Outer view of two upper left anterior teeth and the whole lower Icit toothset

lextpldte 2 . Oxywtus hriimensis (OGILBY, 1893). Male 'ifiOinm 11 ol the same lower left loothstt

cauaht oil Wollongon New South Wales Australia Diaaraph

Contributions to the odontological study of living Chondrichthyes / 2 7

The crown is twice as high as the crown base width and as high as the root The symphyscal tooth has a symmetrical triangular crown The lateral teeth maintain symmetrical less high and narrower toward the commissure Both mesial and distal cutting edges are smooth The outer face is strongly convex and a broad apron extends nearly to the root base The apron is arched at the base and slightly overhangs the root A true outer or inner ornamenta­tion IS absent The root is elongated and has a moie or less rectangular ap­pearance The basal edges of the loot are slightly rounded A foramen is present at each side of the apron The inner face is flat showing sometimes a median apeiture near the crown-loot junction A shallow less developed medio-basal sulcus is present

LOWER JAW

I he teeth are strongly compressed and interlocked The crown base width is appiox 30% less than its height, and also 30% the lOot height The crown is high and symmetri cally triangulai in the symphyscal teeth but becomes incieas-ingly asymmetrical and less high in lateial and commissural teeth The crown possesses a lelatnely well developed lounded blade at each basal edge, continued upward as a poorly developed seriation which disappears totally toward the apex The mesial blade is absent at lateial teeth and those toward the commissuie Both cutting edges are more or less straight The outer face ol the crown is convex and a veiy broad apron extends nearly to the root base The apron is not overhanging the root but forms one part with it From the crown-ioot junc­tion downward the apron continues its width and moie oi less narrows to hall its size neai its lowest pait A shallow aperture is present at each side of the apion The basal edges of the root are slightly rounded A weak outer mesial depres sion IS also due to interlocking On the inner face ot the ciown there is a well developed uvula without basal costules or depression A laige median aperture is piesent at each side of the uvula and one large median aperluic below the uvula Ashoit broad medio ba sal sulcus is present Two to four foramina surround the sul cus, and several scattered foiamina are on the outer basal edge of the root A weak innei distal depression is due to in terlocking oi the lower teeth

Oxynotus centnna (LINNAEUS, 1758) LINNAEUS, 1758 Squalus centnna Systema Naturae

Ed 10(1) 233 Plates 4 to 6

This species shows a strong dignathic heterodonty and a weak monognathic heterodonty The root is always anaulacorhizid The dimensions of the lower teeth are subcentiimetncal, those of the upper teeth plurimilimctrical in size

UPPER JAW

The teeth are compressed having a more or less vertically elongated crown and root The height of the crown is twice as high as the ciown base width but half the lOOt height The symphyscal tooth has a symmetrical triangular crown The lateral teeth show a crown, becoming increasingly asymmetrical, less high and broader based toward the commissure Both mesial and distal cutting edges are smooth

The outer face is strongly convex and a bioad apron extends nearly to the root base The apron is not o\erhanging the lOOt but forms one part with it A true outei or inner ornamenta­tion IS absent The root IS elongated and has a more or less rcctangulai ap­pearance From the ciown root junction downwaid the root is narrowing and the basal edges aie slightly rounded Two or three foramina aie piesent at each side of the apron The in ner face is flat showing a median aperture near the crown loot lunction sometimes a poorly developed median \eitical gioove is present which is moie distinct on the lateial and posterior teeth A deep medio-basal sulcus is always piesent

LOWER JAW

The teeth are strongly compressed and interlocked The ciown base width is equal to its height but half the root height The crown is high and symmetrically tiiangular in the sym physial teeth but becomes increasingly asymmetrical and less high in lateral and commissural teeth The crown pos­sesses a relatively small bluntly rounded blade at each basal edge, continued upward as strong serration which becomes 1 educed in upper crown half and finally disappcais totally toward the apex The mesial blade diminishes in size on tooth positions toward the commissuie Both cutting edges are strongly sigmoid The outer face ot the crown is convex and a bioad apion ex­tends nearly to the loot base The apion is not oveihanging the 1 oot but forms one part with it From the crown root junc tion downward the apron is narrowing to half its size A large aperture is present at each side of the apron Near the junction oi the apron and root some vertical protuberances are present The basal edges of the root are slightly rounded A weak outer mesial depression is also due to interlocking On the inner face of the crown there is a rectangular uvula at the symphyscal tooth that becomes more oblique and less developed in teeth toward the commissure The uvula presents a basal depression A large median aperture is present at each side of the uvula and one large, median aper­ture below the basal depression A short broad, medio-basal sulcus IS present Two to four foramina surround the sulcus, and several scattered foramina are on the outer basal edge of the root A weak inner distal depression is due to interlocking of the lower teeth

8 J. HERMAN. M. HOVESTADT-EULER & D.C. HOVESTADT

width, but hall the root height. The symphyscal tooth has a symmetrical triangular crown with slightly arched cutting edges The lateral teeth maintain symmetrical, less high, and narrower toward the commissure. Both mesial and distal cut­ting edges arc smooth. The outer face is strongly convex and a broad apron extends nearly to the root base. The apron is arched at the base and slightly overhangs the root. A true outer or inner ornamenta­tion is absent. The root is elongated and has a more or less rectangular ap­pearance with a slight constriction half way its height. The root is slightly narrowing at he base and the basal edges arc slightly rounded. Foramina are absent at each side of the apron. The inner face is flat showing a median aperture near the crown-root junction, becoming less developed in lateral teeth and disappears near the commissural positions. A deep medio-basal sulcus is always present.

LOWER JAW

The teeth arc strongly compressed and interlocked. The crown base width is equal to its height, but half the root height. The crown is high and symmetrically triangular in the symphyscal teeth but becomes increasingly asymmetrical and less high in lateral and commissural teeth. The crown possesses a relatively well developed rounded blade at each basal edge, continued upward as a poorly developed serra­tion, which disappears totally toward the apex. The mesial blade is absent at lateral teeth and those toward the commis­sure. Both cutting edges are slightly sigmoid. The outer face of the crown is convex and a broad apron ex­tends nearly to the root base. The apron is not overhanging the root but forms one part with it. From the crown-root junc­tion downward, the apron continues its width and more or less narrows to half its size near its lowest part. A shallow

Textplate 4 : Oxynotus paradoxus FRADE, 1929. Female 920mm t 1., caught oil north-west Ireland, 540m depth, Ireland Diagraph ot whole lower Icit tooihsct and of the symphyscal tooth (inner side) Magnil'ication xl4.

Oxynotus paradoxus FRADE, 1929

Bok'tini de Sociedadc Forliigiic.sa de Ciencias nuturais. Lisboa. 10(22): 26.1-267, fig. 1. Tcxtplatcs 3. 4 . plates 7 to 10.

This species shows a strong dignathic hctcrodonty and a weak nionognathic hctcrodonty. The root is always anaulacorhi/.id. The dimensions of the lower teeth are subcentrimetrical, those of the upper teeth plurimilimetrical in size.

UPPER JAW

The teeth are compressed, having a more or less vertically elongated crown and root. The height of the crown is twice as hich as the crown base

Textplate 3 : Oxynotus paradoxus FRADE, 1929. Female 920mm t.l., caught off north-west Ireland, 540m depth. Ireland. Outer view of the upper dentition. Magnification x6.

Contributions to the odontological study ot living Chondrichthyes / 2

aperture is present at each side of the apron The basal edges of the root are slightly rounded A weak outer mesial depres­sion IS also due to interlocking On the inner face of the crown there is a uvula presenting coarse basal costulcs A large median aperture is piesent at each side of the u\ula and one large, median aperture below the uvula A short broad mcdio-basal sulcus is present Two to four foramina surround the sulcus and several scattered foramina are on the outer basal edge of the i oot A weak inner distal depression is due to inteilocking of the lower teeth

Interspecific differential diagnosis

UPPER JAW

The teeth of O centnna s uppei jaw become oblique toward the commissure with the outer apron not overhanging the root Those of O pmadoxus and O biuinensis maintain straight and the outer apion o\ei hangs the root The cutting edges of the crown of O pmadoxus are slightly arched which aie straight in O centnna and O biuniensis The

height of the crown is twice as high as the crown base width, but half the root height in O bruniensis, O centnna and O paradoxus

LOWER JAW

The teeth of O centnna\ lower jaw possess strongly sig moid cutting edges that are less sigmoid in O paradoxus and more or less straight in O bruniensis The distal blade is small and poorly developed in O centnna, but well devel­oped in O bruniensis and O paradoxus in opposite to the mesial and distal serration that is poorly developed in O biunieinis and O paradoxus but well de\elopcd in O centnna

The crown base width is equal to its height, and half the lOot height in O centnna and O paradoxus but 30% less wide than the crown height and root height in O bntniensis The apron is gradually narrowing downward to half its size in O centnna, but continues its width downward in O biuniensis and O paiadoxus The uvula possesses a basal depression in O biuniensis coarse basal costules in O paradoxus, and is smooth in O bruniensis

Character detail Species

Upper jav. teeth toward commissuie oblique

Upper jaw teeth apron overhangs the root

Upper jaw teeth cutting edges shape arched

Upper jaw teeth crown height twice the crown base width but half the loot height

Upper teeth apron gradually narrows downwards

Lower jaw teeth cutting edges shape sigmoid

Lower jaw teeth cutting edges shape straight

Lower jaw teeth distal blade well developed

Lower jaw teeth serration well developed

Lower jaw teeth crown base width equals height and half the root height

Lower jaw teeth crown base width 307^ less than height and "ÏOVr of loot height

Lower jaw teeth apron gradually narrows downwards

Lower jaw teeth uvula with basal depression

Lower jaw teeth uvula with coarse basal costules

Lower jaw teeth uvula smooth

Oxynotuf bruniensis

No

Yes

No

Yes

No

No

Yes

Yes

No

No

Yes

No

No

No

Yes

Oxynotus centnna

Yes

No

No

Yes

Yes

Yes

No

No

Yes

Yes

No

Yes

Yes

No

No

Oxynotus paradoxus

No

Yes

Yes

Yes

No

Yes

No

Yes

No

Yes

No

No

No

Yes

No

Table 1

10 J HERMAN M HOVESTADT-EULFR & D C HOVESTADT

Conclusions

Although gcncially the ihicc species shaie many tooth moi-

phological chaiacte is , some signilicant diflcienccs appeal in

botii uppci and lowci j a w (sec table 1 above)

O centuna shares uppci and lowci teeth dimensions and

lowei teeth sigmoid shape ol the cutting edges with O

paiadoxus but none ol the characters with O hntmensis

O paiadoxHs shares an overhanging apron ol the upper teeth

and a well developed distal blade with O hinniLUSis

O hiuntensn is unique by straight cutting edges and a c i o w n

base width ^ 0 % less than its height and 30% ol root height in

the lower teeth

O centiina is unique bv possessing lateral and commissuia!

teeth becoming oblique with a giadual l ) narrowing apion in

the uppei teeth and an apion giadually narrowing down-

waids a u \ u l a with a basal depicssion and a well developed

serration on the cutting edges in the lowei teeth

O paradoxus is unique by arch-shaped cutting edges in the

upper j aw teeth and a u \ u l a with coarse basal costules in the

lowei teeth

The thiec species share the crown height that equals loot but

IS hall the root height in the uppei teeth

Acknowledements

Authors like to thank Di G Lenglet Institut royal des

Sciences Natuiel les de Belgique and Dr M McGrouthei ,

Australian Museum Ichthyology Section for giving access

to specimens at their disposal The SEM photographs were

taken by J Cillis (Institut royal dcs Sciences naturelles de

Belgique)

Bibl iography

BlGlLOW H B & SCHROlDLR W C 1948 Fishes of the Western North Atlantic Part 1 Mtmoiis Seauh Foundation foi Manni Re seaich New Haven 576p

CADFNAT J &. BLACHL J 1981 Rcquins de Mediterrancc ct

d Atlantiquc (plus parliculierement de la Cote Occidentale d'Atrique) Editions de I Office de la Reclieiche Scientifiqiie ct Technique Outie Mei Collection Faunc Tit)puale Pans 22 1 4 1 -149

CASIER E , 1961 Transformation des systemes dc fixation et de vascularisation dentaires dans 1 evolution des selaciens du Sous-Ordrc des Squalilormes Meinoiies de I Institut loxal des Sciences natuielles dc Ihli;u/iic Bruxelles 2 " ^ Serie 6') 61p

CERVIGON F 1961 Una nucva especic dc 0\\/ï()/;« de las costas de Venezuela Ncnedadcs Cientifica Contiihuctones ocasionales del Musco dc Histoiia Natuial La Salle Seiie zooloi;ica Caracas 27 1-10 4 1igs

CoMPAGNOLJV 1984 FAG species catalogue Vol 4 Sharks of the world An annotated and illustrated catalogue ol shark species known to date Part I Hcxanchiformes to Lamniformes FAAO Fishenes Synopsis Roma (125) Vol 4 Part I 24 129

FRADI F 1929 Une nouvelle espece ou une aberration indniduellc de 1 Oxxnotus centuna (L ) Boletiin de Sociedade Poilu^uesa dc Cuncias natuiais Lisboa 10(22) 263-267 fig 1

GARRICK J A F 1960 Studies on New Zealand Elasmohranchii XI Squdloids of the genera Deania ttinoplcius Oxxnotiis and üalalias in New Zealand waters Tiansaction oj the loxal Soc letx of Ncu Zealand Wellington 88(3) 519-557, 6lig

H I R M A N J H0VESTAI5T-EUI ER M & HOVESTADT D 1989 Con­

tributions to the stud\ of the comparative morphology of teeth and other rclc\ant ichthyodorulitcs in li\mg supraspecific taxa of Chondrichtyan lishcs Part A Selachu N° 3 Order Squalilormes Families Echinorhinidae Oxynotidae and Squalidae Bulletin de I Institut icnal des Sciences natuielles de Belgique Bioloi^ie Bruxelles 59 101-157

HERMAN J Hovi STADT-EULER M & HOVLSTADT D , 2003 Con

trihutions to the study of the comparative morphology of teeth and other relc\ant ichthvdorulites in li\mg supraspecific taxa of Chondrichthyan fishes Part A Selachu Addendum to 1 Order Hcxanchiformes 2 Order Carcharhiniformes 3 Order Squall-formes Tooth \asculan/ation and phvlogenetic interpretation Bul­letin de I Institut loxal des Sciences ncUuielle'i de Belgique Biologie Bruxelles 73 5 26

LAST PR & STEVENS J D 1994 ShaiksandRaxsofAustialia

CSIRO division of Fisheries Hobart 513p,84pl

LINNAEUS K , 1758 Sysiema Naturae Ed 10 1 233

O G I L B Y J D 1893 Description of a new shark from the Tasmanian coast RLcoidsofiheAustialianMuMuin Sidney 2(5) 62-63

H E R M A N , J

IRSNB, Service G e o l o g i q u e d c Belgique Rue Jennci 13, B - 1000 Brussels Belgium

E mail J heiman (j*skynet be

H O V E S T A D T E U L E R M & HOVESTADT, D C

Merwedelaan 6

N L - 4 5 3 5 E T Terncu/cn The Netherlands

E-mail dmho \c s t@/ee l andne t nl

Contributions to the odontological study of living Chondnchthyes / 2 11

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Plate 2 : Oxynotus hrunieiisi\ (OCILBY, 1893). Male SóOmm t 1 , caught off Wollongon New-South-Wales Auslralia Outer and uiner \iews ol two upper anterior teeth

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Plate 3 : Oxynotus hruniensis (OGILBY, 1893). Male " óOmm 11 , taught oil Wollongon New-South Wales, Australia Inner and outer views ol the thiee first lower teeth

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Pldte 4 : Oxynotus centrina (LiNNALUS, 1758). Female 460mm t I Magnitieation x 9

caughl Cap-dcs-Biches, Om depth Dakar, Senegal Diagraph ol the whole lower toothset (inner \iew)

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Plate 5 : Oxynotus centriiia (hlNNWV^, IISH). Female 460mm 11 caught Cap des Biches 30m depth, Dakar Senegal Outei and inner views ol uppei paiasymphyseal lateral and commissural teeth Magnilication x SO

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Plate 6 : Oxynottis centnna (LlNNAEUS, 1758) Female 460mm t 1 commissural lower teeth Magnification x20

caught Cap des-Biches 30m depth Dakar, Senegal Outer and iner views ol symphyseal, third and

Contributions to the odontological study of living Chondrichthyes / 2 17

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Plate 8 : Oxynotus paradoxus FRADE, 1929. Female 920nini 1.1.. eaiighl oft' nortli-wesl Ireland. 54()ni deplh. Ireland. Outer view of ilie whole lower toothset.

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Plate 9 : Oxynotm paradoxus FRADt, 1929. Female 92()mm t I , caught oil north-west Ireland, ')4()in depth, Ireland Outer view ol the lowei light teeth (without the symphyseal)

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P\dte U) -.Oxyiiolus paradoxus FRADK, 1929. Female 920mni t I taught olf north-west Ireland 540111 depth Ireland Inner view ol the lower right teeth (without the s>niph>seal)