'' BULLETIN DE L'INSTITUT ROYAL DES SCIENCES NATURELLES DE BELGIQUE, BIOLOGIE, 75: 5-20, 2005 BULLETIN VAN HET KONI NKLIJK BELGISCH INSTITUUT VOOR NATUURWETENSCHAPPEN, BIOLOGIE, 75: 5-20, 2005 Contributions to the odontological study of living ChondrichthY,es. 2. The genus Oxynotus RAFINESQUE, 1810 by J. HERMAN, M. HOVESTADT-EULER & D.C. HOVESTADT Abstract: The tooth morphology of three of the four species of the Material genu s Oxynotus is described and partl y illustrated by SEM photo­ graphs. An interspecifi c diagno sis reveals the tooth morphol ogical For thi s stu dy , fo ll owing material was avai lable : Oxynotus differences between th e species 0. bmniensis, 0. centrina and 0. bruniensis : two males, Oxynotus centrina: 13 males and 16 paradoxus. females , Oxynotus paradoxus: 5 males and 3 females . Key words: Odontology - Chondrichthyes - Squaliformes - Oxynotidae - Oxynotus - Tooth morphology. Oxynotus RAFINESQUE, 1810 Resume: La morphologie dentaire de trois des quatre especes du genre 0.\)'nollts est decrite et fi guree partiellement a !'aide de cl i­ The genus Oxynotus compri ses four species : 0 .bruniensis ches MEB . Une diagnose interspec ifiq ue precise les differences morphologiques dentaires observees entre les especes 0. (OGILB Y, 1893), 0. caribbaeus, CERY IGON , 196 1, the type bruniensis, 0. centrina et 0 . parado.xus. species 0. centrina (LINNAEUS , 175 8) and 0 . paradoxus FR ADE, 1929. Mots-des: Odontologie - Chondrichth yes - Squali formes - Oxynotidae- O.~J · n olt.ls- Morphologie dent aire . Oxynotus bruniensis (OGILBY, 1893) Kurzfassung: Di e Zahnmorphologie vo n drei vo n der vier Arten OGILBY J.D ., 1893 : Centrina bruniensis. Records of th e der Gattung Oxynotus werden besc hrieben und teilweise illustri ert Australian Museum. Sidney. 2(5) :62-63. mit REM Photos. Eine interspezifisc he Di agno se zeigt die zahn ­ Textplates I ,2, plates I to 3 morphologische Unterschi ede zwischen den Arten 0 . bruniensis, '~ 0. cemrina und 0. paradoxus. For the first schematic illustrati on uf upper and lower teeth Schliisselworter: Odontologie- Chondri chthyes - Squali formes­ see GARRICK J.A.F. , . 1960 : Studies on New Zealand Oxynotidae - Oxynotus- Zahnmorphologie. Elasmobranchii . XI. Squaloids of the genera Deania, Etn wpterus, Oxynotus and Dalatias in New Zealand waters. Tran saction of th e royal Society of New Zealand. Wellington. Introduction 88(3): 51 9-557,6 figs. For a second one, with correct illustrations of outer faces of With the excepti on of 0 . centrina, the tooth morphol ogy of one upper tooth and one lower tooth see LAST P.R. & the taxa of the genu s Oxynotus is poorl y kn ow n. For thi s STEVENS J.D. , 1994 : Sharks and Rays ofAustralia. CSIRO study tooth materi al was avai lab le of 0 . bruniensis, 0. division of Fisheries. Sidney. 513p., 84pl. (cf. p. 105). centrina and 0 . paradoxus. Due to lacking tooth samples of 0 . caribbaeus thi s species could not be incorporated in this This species shows a strong dignathic heterodonty and a study. The tooth morph ology of 0 . bruniensis and 0. weak monognathi c heterodonty. The root is always paradoxus will be described and illustrated. 0 . centrina, anau lacorhi zid . which was described and illustrated by HER1vlAN, The dimensions of the lower teeth are subcentrimetrical, HOYESTADT-EULER & HOYESTADT ( 1989), wi ll be used here those of the upper teeth plurimilimetri cal in size. and more information, as well as more illustrati ons are pro­ vided. An interspecific di ffe renti al di agnos is reveals their UPPER JAW tooth morphological differences. For the terminology used here, see HER MAN, HOYESTADT-EULER and HOVESTADT The teeth are compressed, havin g a more or less verticall y 1989. elongated crow n and root. ,, 6 J. HERMAN, M. HOVESTADT-EULER & D.C. HOVESTADT Textplate 1 : Oxynotus bnmiensis (OGILBY, 1893). Male 560mm t.l., caught off Wollongon, New-South-Wales, Australia. Outer view of two upper left anterior teeth and the whole lower left toothset Textplate 2 : Oxynotus bruniensis (OGILBY, 1893). Male 560mm t.l. , caught off Woll ongon, New-South-Wales, Australi a. Diagraph of the same lower left toothset. I I Contributi ons to the odontological study of li vin g Chondrichthyes I ? 7 The crown is twice as hi gh as the crown base width and as UPPER JAW hi gh as the root. The symphyseal tooth has a symmetri cal tri angul ar crown. The lateral teeth maintain symmetri cal, The teeth are compressed, havin g a more or less verticall y less hi gh, and narrower toward the commissure. Both mesial elongated crown and root. and distal cutting edges are smooth. The height of the crown is twice as high as the crown base The outer face is strongly convex and a broad apron extends width , but half the root height. The symphyseal tooth has a nearl y to the root base. The apron is arched at the base and symmetri cal tri angul ar crown. The lateral teeth show a slightly overhangs the root. A true outer or inner ornamenta­ crown, becoming increasingly asym m~ tri ca l , less hi gh, and tion is absent. broader based toward the commissure. Both mesial and di stal The root is elongated and has a more or less rectangular ap­ cutting edges are smooth . pearance. The basal edges of the root are sli ghtl y rounded. A The outer face is strongly convex and a broad apron extends fo ramen is present at each side of the apron. The inner face is nearl y to the root base. The apron is not overhangin g the root flat, showin g sometimes a median aperture near the crown­ but forms one part with it. A true outer or inner orn amenta­ rootjuncti on. A shallow less developed media-basal sulcus is ti on is absent. present. The root is elongated and has a more or less rectangul ar ap­ pearance. From the crown-root juncti on downward , the root is narrowin g and the basal edges are sli ghtly rounded. Two or LOWER JAW three foramina are present at each side of the apron. The in­ The teeth are strongly compressed and interlocked. The ner face is flat, showing a median aperture near the crown­ crown base width is approx. 30% less th an its height , and root junction; sometimes a poorly developed median vertical also 30% the root height. The crown is hi gh and symmetri ­ groove is present, which is more distinct on the lateral and call y tri angul ar in the symphyseal teeth but becomes increas­ posterior teeth . A deep media -basal sulcus is always present. ingly asymmetri cal and less hi gh in lateral and commissural teeth . The crown possesses a relatively well developed LOWER JAW rounded blade at each basal edge, continued upward as a poorfy developed serrati on, which disappears totall y toward The teeth are strongly compressed and interlocked. The the apex. The mesial blade is absent at lateral teeth and those crown base width is equal to its height, but half the root toward the commissure. Both cuttin g edcres are more or less height. straight. ~ "' The crown is high and symmetricall y tri angul ar in the sym­ The outer face of the crown is convex and a very broad apron physial teeth but becomes increasingly asymmetrical and extends nearly to the root base. The apron is not overhangi ng less hi gh in lateral and commissural teeth. The crown pos­ the root but forms one part with it. From the crown-root junc­ sesses a relatively small , bluntly ro unded blade at each basal ti on downward, the apron continues its width and more or edge, continued upward as strong serrati on, which becomes less narrows to half its size ne(\r its lowest part. A shall ow reduced in upper crown half and fi nall y disappears totall y aperture is present at each side of the apron. The basal edges toward the apex. The mesial bl ade diminishes in size on tooth of the root are sli ghtl y rounded. A weak outer mesial depres­ positi ons toward the commissure. Both cutting edges are sion is also due to in terlocki ng. strongly sigmoid . On the inner face of the crown there is a well developed The outer face of the crown is convex and a broad apron ex­ tends nearly to the root base. The apron is not overhancr in cr uvula without basal costul es or depression. A large median "' "' aperture is present at each side of the uvul a and one larcre the root but fonm one part with it. From the crown-root junc- median aperture below the uvul a. A short, broad, m e d io-ba~ tion downward, the apron is narrowin g to half its size. A large sal sul cus is present. Two to four foramina surround the sul­ aperture is present at each side of the apron. Near the junction cus, and several scattered foramina are on the outer basal o f the apron and root, some vertical protuberances are edge of the root. A weak inner di stal depression is due to in­ present. The basal edges of the root are sli ghtly rounded. A terlocki ng of the lower teeth. weak outer mesial depression is also due to interl ockin g. On the inner face of the crown there is a rectangular uvula at the symphyseal tooth that becomes more oblique and less Oxynotus centrina (LINNAEUS, 1758) developed in teeth toward the commissure. The uvul a LlNNAEUS, 175 8 : Squalus centrina. Systema Naturae. presents a basal depression. A large medi an aperture is Ed.