Contributions to the study of the comparative morphology of theeth and other relevant ichtyodorulites in living supraspecific taxa of Chondrichthyan fishes. Part C: Superorder Holocephali 1: Order Chimaeriformes - Suborder Chimaeroidei - Family Callorhync

31 Pages·2001·6.6 MB·English

by  Herman, J

,,
BULLETIN DE L'INSTITUT ROYAL DES SCIENCES NATURELLES DE BELGIQUE, BIOLOGIE, 71: 5-35, 200I
BULLETIN VAN HET KONINKLIJK BELGISCH INSTITUUT VOOR NATUURWETENSCHAPPEN, BIOLOGIE, 71: 5-35, 2001
Contributions to the study of the comparative morphology of teeth and other
relevant ichthyodorulites in living supraspecific taxa of Chondrichthyan fishes.
Editor: M. STEHMANN
Part C: Superorder 1: Order Chimaeriformes Suborder
Holo_~ephali
Chimaeroidei- Family Callorhynchidae- Subfamily Callorhynchinae- Genus:
Callorhinchus, Family Chimaeridae - Genera : Chi1naera and Hydrolagus,
Family Rhinochimaeridae Genera: Harriotta, Neoharriotta, and
Rhinoch i mae ra.
by J. HERMAN, M. HOVESTADT-EULER & D.C. HOVESTADT.
Abstract Part C: Holocephali 1: Order: Chimaeriformes -
Suborder: Chimaeroidei
Part C of this series describes and illustqtes with SEM or
macrophotos the morphology of the tooth plates, the spines of the
first dorsal fin and frontal tenacula of extant holocephalan genera. A General introduction
differential diagnosis and systematic conclusions are summarized
in the results. Part C of this series comprises the Holocephali. Like the
Selachii and Batomorphii, the taxa of this superorder also
Key words: Holocephali - Chimaeriformes - Chimaeroidei -
Callorhynchidae-Chimaeridae-Rhinochimaeridae-Odontology. possess a cartilaginous endoskeleton. However,
holocephalan teeth are not regularly shed like Selachii and
Batomorphii but form slowly and permanently growing,
Resume fused, massive tooth plates in upper and lower jaws.
The Holocephali are subdivided into the three orders
Dans Ia partie C de cette serie, Ia morphologie des plaques den Cochliodontifmmes, Menaspiformes and Chimaerifmmes
taires, ainsi que celle de l'epine de Ia nageoire dorsale et de l'appa (STAHL 1999). The first two orders are only represented by
reil frontal tenaculaire des six genres recents d'Holocephales sont extinct taxa. The order Chimaeriformes comprises the subor
decrites et figurees (macrophotos ou cliches MEB). Diagnose dif ders Echinochimaeroidei, Squalorajoidei, Myriacanthoidei,
ferentielle et conclusions systematiques sont presentees dans les Chimaeropsoidei and Chimaeroidei. The latter only are rep
conclusions.
resented by both extinct and extant taxa, the others only by
Mots-des: Holocephali - Chimaeriformes - Chimaeroidei - extinct taxa. The Chimaeroidei comprise the families
Callorhynchidae-Chimaeridae-Rhinochimaeridae- Odontologie. Rhinochimaeridae, Chimaeridae and Callorhynchidae. The
latter are subdivided after STAHL ( 1999) into the sub
families Callorhynchinae and Edaphodontinae.
Kurzfassung Edaphodontinae comprise extinct taxa only and, like all other
extinct taxa, are not included in this study.
Teil C dieser Serie beschreibt und illustriert durch REM oder If available, the dorsal fin spines and the frontal tenacula (a
macrophotos die Morphologie der Zahnplatten, die Stacheln der feature only) are described and illustrated as well.
erste dorsaler Flosse und Stirnklasper von holocephaler rezente The authors will not draw any nomenclatorially valid conclu
Gattungen. Eine Differentialdiagnose und systematische Schluss sions.
folgerung fassen die Ergebnisse zusammen.
The full bibliographical reference for each species will be
Schiisselwiirter: Holocephali - Chimaeriformes - Chimaeroidei - given in the descriptive section and not be repeated under
Callorhynchidae- Chimaeridae- Rhinochimaeridae- Odontologie. literature references.
I I
6 J. HERMAN, M. HOVESTADT-EULER & D.C. HOVESTADT
Terminology MESIAL SECTION
This is the part of the lingual face forming the symphysial
The following tenninology is used in this issue for describing connection with the opposite vomerine or mandibular tooth
the tooth plates: plate, respectively.
Vomerine tooth plate =Upper anterior tooth plate. DISTAL SECTION
Palatal tooth plate =Upper posterior tooth plate.
This is the part interiocking of the two vomerine and the
Mandibular tooth plate= Lower tooth plate.
palatal tooth plates, respectively. (See textfigure I below)
Tritor rods =Thin inner columns of hypem1ine-
ralized tissue.
Family: Callorhynchidae GARMAN, 1901
Tritor pads =Rounded or oval external tips of
internal tritor rods on the occlusal
Subfamily: Callorhynchinae STAHL, 1999
surface, longitudinally abraded
tritor rods on the lingual surface,
INTRODUCTION
or hypermineralized tissue of the
The Callorynchinae comprise seven genera, of which only
central ridge of mandibular tooth
Callorhinchus is represented by living species.
plates.
Generally, the terminology used by PATTERSON (1992) is
used. However, extant chimaeroids have additional features Genus: Callorhinchus LACEPEDE, 1798
that are added below:
The distal margin is introduced as a fourth margin, which is This genus is represented by four extinct species (STAHL,
often lost due to abrasion; lingual and labial margins join in a 1999) and the three extant species (DIDIER, 1995) C.
distal angle in such cases. Symphysial border is replaced by capensis, C. milii and the type species C. callorhynchus. Spe
mesial margin. Palatal tooth plates have no symphysial mar cies of this genus possess an additional patch of dermal
gin, and mesial margin applies to all types of tooth plates. denticles opposite those of the frontal tenaculum, directly at
Further, is 'mesial' commonly used as the opposite of tached to the skull integument. These denticles are equal to
'distal'. those of the frontal tenaculum and are not additionally de
For the lingual face, two additional terms are introduced scribed but well illustrated on plates I, 3 and 5. This phenom
here: enon seems to be unique for the extant Holocephali; in the
legend of the plates the proposed appelation is tenacular
complex.
Lacking material of the type species, C. capensis and C. milii
Vomerine tooth plate Palatal tooth plate are used for descriptions and illustrations.
(occluso-lingual view) (occluso-lingual view)
Material
Distal section
Lingual
,.,---
The following 4 specimen of 2 species were examined:
Callorhinchus milii
ANSP 177821 · Tooth plates, no data
o
IRSNB R.3455 78 em t.l.
IRSNB R.348jaws, no data
Callorhinchus capensis
Coli. Pierre Coupatez o skull, claspers and dorsal fin
Tritor pads
Callorhinchus m.ilii BORY & SAINT VINCENT, 1823
(Plates l and 2)
Callorhinchus milii BORY & SAINT VINCENT 1823 -
Dictionnaire classique d' Histoire naturelle. Rey et Gravier.
Paris. vol.3, 62, pl.S.
Central fold Chimaera monstrosa HETERODONTY
Lingual
The dentition is dignathic heterodont. Having a single speci
Text figure I -Description of the odontological, spine of the first men available only, neither sexual nor ontogenetic
dorsal fin and tenaculum characters heterodonty could be examined.
I I
Contributions to the study of the comparative morphology of teeth and other relevant ichthyodorulites 7
VOMERINE TOOTH PLATE FRONTAL TENACULUM DENTICLES
The more or less lozenge-shaped plate is about three times as The frontal tenaculum bears approximately a hundred dermal
high as broad. The labial surface is undulated and bent lin denticles on its bulbous distal part, which are set in fourteen
gually from the labial margin towards the lingual margin. more or less regular longitudinal rows. The size of the
The lingual surface possesses an additional mesial and distal denticles diminishes toward the tenaculum's sides. Each der
section. The narrow mesial section is smooth and flat for mal denticle consists of a flat, semi/oval, radiated basal plate
linking with the opposite vomerine plate. The uppermost part and a hook-like cusp in the center on top. The cusp lacks cut
of the broader, concave main section is always abraded, pre ting edges and is smooth. The basal surface each denticle of
senting a single internal 111esial tritor rod along the mesial the semi-oval shaped flange is funnel shaped with a central
margin. The narrow, smooth distal section is sl.ightly con aperture.
cave, forming an interlock with the palatal tooth plate.
Family: Chimaeridae BONAPARTE, 1831
PALATAL TOOTH PLATE
INTRODUCTION
The plate is of more or less trapezoid shape. The distal mar
gin is narrow and about one-third the length of the mesial The Chimaeridae comprises three genera, with Chimaera
one. The mesial margin is slightly arched, both labial and lin represented by extinct as well as extant species, and
gual margins are more or less straight, and the labial one has Hydrolagus represented by extant species only.
a flattened tip. The labial surface presents a large, deep de
pression in which the jaw part fits. A relatively narrow Genus: Chimaera LINNAEUS, 1758
enameloid-like band is present along the upper mesial, labial
and distal margins. This genus is represented by nine extinct species (STAHL,
The lingual surface is slightly undulated and presents a large, 1999) and the six extant species (DIDIER, 1995) C. cubana,
broad and semi-circular tritor pad that is bifurcated toward C. owstoni, C. jordani, C. phantasma, C. pseudomonstrosa
the labial margin. and the type species C. nwnstrosa.
MANDIBULAR TOOTH PLATE
Material
These more or less lozenge-shaped plates have a distal mar
gin that is less than half as long as the mesial one. The mesial The following 13 specimen of the type species were exam
margin is straight and its surface is concave. Tbe distal mar ined:
gin is also straight, but the labial one is arched. The lingual
margin is slightly undulated. The labial surface presents a Chim.aera monstrosa
large, deep depression in which the jaw part fits. A relatively Coll.Herman 9 55 em tl.
narrow enameloid-like band is present along the upper me Coll.Herman 9 58 em tl.
sial, labial and distal margins. The lingual surface presents a Coli.Herman 0 56 em tl.
mesial section forming the connection with the opposite Coll.Herman 0 61 em tl.
mandibular plate. The surface is largely undulated due to the Coll.Hovestadt 0 SO em TL
presence of a relatively broad central ridge. The part at the Coll.Hovestadt 0 44 em TL
labial margin, along the cutting edge of the lingual surface is Coll.Hovestadt 9 95 em TL
lost due to abrasion, with only a large, semi-circular central Coll.Hovestadt 9 75 em TL
tritor pad remaining. Coll.Hovestadt 9 45 qn TL
Coll.Hovestadt 9 45 em TL
Coll.Hovestadt 9 40 em TL
Coli.Hovestadt 9 40 em TL
Callorhinchus capensis DUMERIL, 1865 Coll.Hovestadt 9 10.5 em TL
(Plates 3 to 5)
Callorhinchus capensis DUMERIL, 1865. Histoire naturelle Chimaera monstrosa LINNAEUS, 1758
des poissons ou Ichthyologie generale. Edwards, George, (Plates 6 to 8)
Paris. Vol l, 695, pl. 13, figs 5, Sa.
Chimaera monstrosa LINNAEUS, 1758. Sy tema Natura.
The dorsal fin spine possesses a sharp mesial ridge, which is ed. X, tome I, 824 pp. Nantes & Pisces: 230 -338.
serrated more or less regularly over three-quarters of its
length. The tips of the seiTation is upturned and become HETERODONTY
shorter toward spine's tip. The dentition is dignathic heterodont. Neither sexual nor on
The distal face is a relatively shallow, broad central grove. togenetic heterodonty was found.
The lateral margins bears minute tubercles, with their tips
downturned, along spine's the upper half. The lateral sur VOMERINE TOOTH PLATE
faces are convex in cross-section. The interior of the spine is The more or less rectangular plate is about twice as high as
hollow. broad and a little twisted around its vertical axis. The labial
''
8 J. HERMAN, M. HOVESTADT-EULER & D.C. HOVESTADT
surface is bent from the labial margin towards the lingual The distal face is a relatively shallow central furrow. Its lat
margin. Vertical striae, oriented almost parallel, are present, eral margins bear tubercles, with their tips downtumed, along
formed by the tips of the internal tritor rods at this surface. the spine's upper half. The lateral surfaces are convex in
The lingual surface is subdivided into mesial and distal sub cross-section. The interior part of the spine is hollow.
sections. The nmTow mesial section is smooth and flat to link
with the opposite vomerine plate. The relatively broad main FRONTAL TENACULUM DERMAL DENTfCLES
section bears well-developed, horizontal ridges, of which the The frontal tenaculum bears approximately 70 dermal
mesial and distal edges of which are bent labially, so that denticles on its bulbous distal part, arranged in a patch of ten
each ridge is of trapezoid shape. The surface between these more or less regular longitudinal rows. The size of the
ridges slopes from the top of each ridge to the base of the denticles diminishes toward tenaculum's sides. Each denticle
previous one. Along the labial the cutting edge of the main consists of a more or less flat, semi-oval, radiated basal plate
section the surface is strongly abraded, leaving five to six with a hook-like cusp on top. The basal face of each dermal
tritor rods visible that lay against the labial surface. The nar denticle is funnel shaped with a central aperture.
row, smooth distal section is slightly concave and interlocks Most of the elongated, curved cusps have a central and two
with the palatal tooth plate. lateral cutting edges and smooth surfaces.
PALATAL TOOTH PLATE
Gsnus: Hydrolagus GILL, 1862
The plate appears more or less trapezoid or triangular, de
pending on the presence or absence of a distal margin. This
This genus comprises 17 extant species (DIDIER, 1995): H.
margin is often indistinct due to abbrasion, with a distal angle
affinis, H. africanum, H. alberti, H. barbouri, H. colliei, H.
remaining only. The mesial margin is arched, ~md the labial
deani, H. eidolon, H. lemures, H. macrophtalm.us, H. media,
and lingual margins are slightly sigmoid and joining in a
H. mirabilis, H. novaezealandiae, H. ogilbyi, H.
distal angle. The labial surface is bent lingually from the la
purpurescens, H. waiti, the type species H. mitsukuri and the
bial margin toward lingual margin.
lately decribed H. pallidus. Lacking material of the type spe
The slightly undulated lingual surface bears up to six short
cies the latter species was selected for description and illus
tritor pads along the labial margin and up to five more larger
tration.
elongated mesio-lingual ones. The latter are lined up almost
parallel from the mesial margin toward the distal angle.
Tritor pads are absent closer to the distal angle. If the lingual Material
surface is less abraded, the tritor rods are visibie through the
thin enameloid-like surface layer, in which case elongated, 20 specimen of 5 species were examined:
mesio-lingually directed tritor pads are absent.
Hydro lag us affinl s
Coli. Hovestadt 0 80+ em tl.
MANDIBULAR TOOTH PLATE
The distal margin of this more or less trapezoid plate is less Hydrolagus mirabilis
than half the length of the mesial one. The mesial margin is Coli. Herman 0 68 em tl.
arched, the distal and labial ones more or less straight. The Coli. Herman 0 75 em tl.
mesial and labial margins join in a rounded angle. The lin Coli. Hem1an 0 74 em tl.
gual margin is slightly undulated. The labial surface is Coli. Herman 0 72 em tl.
slightly convex and bent mesio-distally, with the mesial part Coli. Hem1an 0 70 em tl.
bent stronger than the distal one. Vertical striae, in almost Coli. Heiman 0 69 c;n tl.
parallel arrangement, result from the tips of the internal tritor Coli. Heiman 0 68 em tl.
rods that lay against this surface. The mesial section of the Coli. Hem1an 2 65 em tl.
lingual surface presents is narrow, smooth and Oat, to form Coli. Heiman 2 68 em tl.
the link with the opposite mandibular plate. The remaining Coli. Herman 2 70 em tl.
surface is undulated due to the presence of a relatively broad Coli. Heiman 2 72cm tl.
central ridge. Along the labial cutting edge the lingual sur Coli. Herman 2 75 em tl.
face is strongly abraded, leaving six distal and a mesial tritor Coli. Hovestadt 2 74cm tl.
rod visible, that lay against the labial surface, and the tritor Coli. Hovestadt <j! 72 em tl.
pad that supports the central ridge.
Hydrolagus pallidus
Coli. Hovestadt ? 100+ em tl.
The dorsal fin spine possesses three sharp, distinct, mesial
Coli. Hovestadt 0 100+ em tl.
ridges, of which at spine's base the central one is approxi
Coli. Hovestadt <j! 130+ em tl.
mately three times higher than the lateral ones. The distance
at spine's base between the central ridge and each lateral
Hydrolagus novaezealandiae
ridge almost equals the height of the central ridge but nar
ANSP 177870 No data
rows as the spine tapers toward its apex. The height of the
central ridge diminishes toward the apex, and the three ridges Hydrolagus sp.
join to become one ridge close to the apex.
ANSP 177869 No data
I I
Contributions to the study of the comparative morphology of teeth and other relevant ichthyodorulites 9
Hydrolagus pallidus HARDY & STEHMANN, 1990 The dorsal fin spine possesses three sharp, distinct, mesial
(Plates 9 and 10 ) ridges, of which at spine's base the central one is approxi
mately three times higher than the lateral ones. The distance
Hydrolagus pallidus HARDY & STEHMANN, 1990. A new at spine's base between the central ridge and each lateral
deep-water ghost shark, Hydrolagus pallidus ridge almost equals the height of the central rid~e but nar
n.sp.(Holocephali, Chimaeridae), from the Eastern North At rows as the spine tapers toward its apex. The height of the
lantic, and redescription of Hydrolagus affinis (BRITO central ridge diminishes toward the apex, and the three ridges
CAPELLO, 1867). Archiv fur Fisch Wissenschaft 40 (3): join to become one ridge close to the apex. Small tubercles
229-248. with upward pointed tips are found on the lower section of
the central ridge.
The distal face is a relatively shallow central furrow. Its lat
HETERODONTY
eral margins bear tubercles, with their tips downturned, along
The dentition is dignathic heterodont. Neither sexual nor on
the spine's upper half. The lateral surfaces are convex in
togenetic heterodonty was found.
cross-section. The interior part of the spine is hollow.
VOMERINE TOOTH PLATE
FRONTAL TENACULUM DERMAL DENTICLES
The more or less rectangular plate is about twice as high as
The frontal tena_<?)Jium bears approximately 70 dermal
broad and a little twisted around its vertical axis. The labial
denticles on its bulbous distal part, arranged in a patch of ten
surface is bent from the labial margin toward the lingual mar
more or less regular longitudinal rows. The size of the
gin. Vertical striae, oriented almost parallel, are present
denticles diminishes toward tenaculum's sides. Each denticle
fmmed by five to six internal tritor rods that lay against this
consists of a more or less flat, semi-oval, radiated basal plate
surface. The lingual surface is subdivided into mesial and
with a hook-like cusp on top. The basal face of each dermal
distal subsections. The narrow mesial section is smooth and
denticle is funnel shaped with a central aperture.
flat, fmming the link with the opposite vomerine plate. The
Some of the elongated, curved cusps have a central and two
relatively broad main section bears poorly developed hori
lateral cutting edges and smooth surfaces.
zontal ridges. A large part at the labial side, along the cutting
edge of the surface of the main section is strongly abraded,
Family: Rhinochimaeridae BONAPARTE, 1831
leaving five or six tritor rods visible that lay against the labial
surface. The narrow, smooth distal section is slightly concave
INTRODUCTION
and interlocks with the palatal tooth plate.
The Rhinochimaeridae comprise six extinct and the three ex
tant genera Harriotta, Neoharriotta and Rhinochimaera.
PALATAL TOOTH PLATE
This plate is more or less trapezoid. The mesial margin is
Genus: Harriotta GOODE & BEAN, 1895
slightly arched, the lingual margin slightly sigmoid and the
distal one straight and about half the length of the mesial one.
This genus is represented by one extinct species (STAHL,
The labial margin is structured by large indentations between
1999) and the two extant species (DIDIER, 1995) H.
tritor rods, probably caused by abrasion. The labial surface is
haeckeli and the type species H. raleighana. Dorsal fin spine
bent from the labial margin toward the lingual margin. The
and frontal tenaculum were lacking for description and illus
slightly undulated lingual surface bears up to six small tritor
tration.
pads along the labial margin. Larger elohgated mesio-lingual
pads are absent.
MATERIAL
The following 4 specimen of 1 species were examined:
MANDIBULAR TOOTH PLATE
The distal margin of the more or less trapezoid plate is about
Harriotta raleighana
half the length of the mesial one. The mesial margin is
Coli. Hovestadt d' 98 em tl.
slightly arched, the distal and lingual ones are more or less
Coli. Hovestadt <jl 71 em tl.
straight. The labial margin is structured by broad indenta
ANSP 177811 no data
tions between the tritor rods, probably caused by abrasions. o
Coli. Mailhot 75 em tl.
The lingual margin is slightly undulated. The labial surface is
slightly convex and bent mesio-distally, with the mesial part
stronger bent than the distal one. Vertical striae in almost par Harriotta raleighana GOODE & BEAN, 1895
allel mnngement result from the internal tritor rods that lay (Plates 12, 13 and 20)
against this surface. The mesial section of the lingual surface
is narrow, smooth and flat to form the link with the opposite Harriotta raleighana GOODE & BEAN, 1895. Scientific re
mandibular plate. The remaining lingual surface is undulated sults of explorations by the U.S.fish commission steamer
due to the presence of a relatively broad central ridge. The 'Albatros'. No.30. On Hariotta, a new type of chimaeroid
labial margin along the cutting edge of the lingual surface is fish from the deeper waters of the northwestern Atlantic. Pro
strongly abraded leaving six distal and one larger mesial ceedings of the United States National Museum 17 (1014):
tritor rod visible that lay against the labial surface. 471-473.
I'
10 J. HERMAN, M. HOYESTADT-EULER & D.C. HOYESTADT
HETERODONTY present at each side of the ridge up to half the spine's lenght.
The dentition is dignathic heterodont. Neither sexual nor on The distal face is slightly concave or almost flat, with a low
togenetic heterodonty were found. central ridge at the lower half of the spine. Its lateral margins
bear minute tubercles, with their tips downturned, along the
VOMERINE TOOTH PLATE spine's upper two-third part. The lateral smfaces are convex
in cross-section. The interior part of the spine is hollow.
The plate is mesially enlarged. The mesial edge of the labial
margin forms a very sharp angle (about 20°) with the mesial
FRONTAL TENACULUM DERMAL DENTICLES
margin, forming a hook-shaped cutting edge with the arched
mesial margin. The labial cutting edge abruptly bends hori Te frontal tenaculum is three as long as broad and bears ap
zontally and finally forms a rounded junction with the distal proximately dermal denticles on its bulbous distal part,
margin, which is slightly arched. The lingual margin is arrranged in a patch of eight more or less regular longitudinal
straight. rows. The size of the denticles diminishes toward tenacu
The plate is a little twisted around its vertical axis. The labial lum's sides. Each denticle consists of a hook-like cusp on
surface is bent from the labial margin towards the lingual top. The basal face of each dermal denticle is funnel shaped
one. Vertical striae, oriented almost parallel, are present with a central aperture.
formed by five to six internal tritor rods that lay against this Cutting edges on the elongated arched cusp are present at
surface. The lingual surface is subdivided into mesial and each side an<;t,surfaces are smooth.
distal subsections. The narrow mesial section is smooth and
flat, forming the link with the opposite vomerine plate. The
relatively broad main section is convex and smooth. With the Genus: Neoharriotta BIGELOW & SCHROEDER, 1950
exception of the mesial part, a large part at the labial side,
along the cutting edge of the surface of the main section is This genus comprises the three extant species (DIDIER,
strongly abraded, leaving up to ten tritor rods visible that lay 1995), N. carri and N. pumila and the type species N.
against the labial surface. The narrow, smooth distal section pinnata. Lacking material of the type species, N. pumila is
is slightly concave and interlocks with the palatal tooth plate. used for descriptjon and illustration. Dorsal fin spine and
frontal tenaculum were lacking for description and illustra
PALATAL TOOTH PLATE tion.
This plate is more or less trapezoid. The mesial margin is
MATERIAL
slightly arched, the lingual margin slightly ·sigmoid and the
distal one straight and about one-quarter the length of the The following I specimen of I species were examined:
mesial margin. The labial surface is bent lingually from the
labial margin towards lingual one. Neoharriotta pwnila
o
The slightly undulated lingual surface bears up to seven dis ANSP 172538 (Paratype) 21 em tl., isolated tooth
tinct tritor pads along the labial margin. Several tritor pads plates only.
are merged in the mesio-mid section several, forming a large
convex surface.
Neoharriotta pumila DIDIER & STEHMANN, 1996
MANDIBULAR TOOTH PLATE (Plate 14)
The more or less trapezoid plate has a distal margin that is
Neoharriotta pumila DIDIER & STEHMANN 1996.
about one-fifth of the length of the· mesial one. The mesial
Neoharriotta pwnila, a new species of Longnose Chimaera
margin is slightly arched, the distal and lingual ones are more
or less strajght. from the Northwestern Indian Ocean (Pisces, Holocephali,
Rhinochimaeridae). Copeia 1996 (4): 955-965.
The labial margin is structured by a few rounded indentations
between the tritor rods, probably caused by abrasions. The
HETERODONTY
lingual margin is slightly undulated. The labial surface is
slightly convex and bent mesio-distally, with the mesial part The dentition is dignathic heterodont. Sexual or ontogenetic
stronger bent than the distal one. Vertical striae in almost par heterodonty could not be examined with only a single speci
allel arrangement result from the internal tritor rods that lay men available.
against this surface. The mesial section of the lingual surface
is narrow, smooth and flat to form the link with the opposite VOMERINE TOOTH PLATE
mandibular plate. The remaining lingual surface is undulated The plate is more or less quadrangular. The plate is a little
due to the presence of a relatively broad central ridge, which twisted around its vertical axis. The labial surface is bent
is supported by a large tritor pad. The labial margin along the from the labial margin toward the lingual margin.
cutting edge of the lingual surface, is strongly abraded, leav Vertical striae, oriented almost parallel, are present formed
ing five distal and three larger mesial tritor rod visible that by the internal tritor rods that lay against this surface. The
lay against the labial surface. lingual surface is subdivided into mesial and distal subsec
tions. The narrow mesial section is smooth and flat, fanning
The dorsal fin spine possesses one sharp mesial ridge that the link with the opposite vomerine plate. The relatively
diminishes in height toward the apex. Minute knobs are broad main section is convex and smooth. A large part at the
''
Contributions to the study of the comparative morphology of teeth and other relevant ichthyodorulites II
labial side, along the cutting edge of the surface of the main Coli. Hovestadt 120 ern tl.
section is strongly abraded, leaving nine tritor rods visible Coli. Hovestadt 150 ern tl.
that lay against the labial surface and additionally five mesial Coli. Hovestadt 150 em tl.
ones. The narrow, smooth distal section is slightly concave
and interlocks with the palatal tooth plate. Rhinochimaera pacifica
ANSP 177812 No data
PALATAL TOOTH PLATE
This plate is more or less trapezoid. Its mesial, lingual and
distal margins are straight and the distal one is one third of Rhinochimaera atlantica HOLT & BYRNE, 1909
the length of the mesial margin only. The labial margin is (Plates 15 to 19)
straight with a flattened tip. The labial surface is bent from
the labial margin towards lingual one. Rhinochimaera atlamica HOLT & BYRNE, 1909. Prelimi
The slightly undulated lingual surface bears up to ten, small, nary note on some fishes from the Irish Atlantic slope. An
distally located tritor rods, a large one merged with the tritor nals and Magazine of Natural History, series 8, 3: 279-280.
pad of the central ridge and three smaller tritor pads that are
mesially, all located along the labial margin. HETERODONTY
The dentition is dignathic heterodont. Neither sexual nor on
MANDIBULAR TOOTH PLATE
togenetic heterodonty"\vas found.
The distal margin of this lozenge-shaped plate is about half
the length of the mesial one. The mesial and distal margins VOMERINE TOOTH PLATE
are straight, the lingual one is arched. The labial margin is
This plate has an arched mesial margin. The mesial edge of
structured by rounded indentations between the tritor rods, the labial margin makes a sharp angle (about 60°) with the
probably caused by abrasions. The lingual margin is undu mesial margin. The labial cutting edge gradually slopes to
lated, due to a well-developed central ridge. The labial sur wards the distal angle. The lingual margin is straight.
face is slightly convex and bent mesio-distally, with the me
The labial surface is bent from the labial margin towards the
sial part stronger bent than the distal one. Vertical striae in
lingual margin. Neither tritor rods nor tritor pads are present.
almost parallel arrangement result from the internal tritor The lingual surface is subdivided into mesial and distal sub
rods that lay against this surface. The mesial section of the sections. The narrow mesial section is smooth and flat, form
lingual surface is narrow, smooth and flat to form the link ing the link with the opposite vomerine plate. The relatively
with the opposite mandibular plate. The remaining lingual
broad main section is convex and smooth. A large part at the
surface is strongly undulated due to the presence of a rela
labial side, along the cutting edge of the surface of the main
tively broad central ridge. The labial margin along the cutting
section is strongly abraded, leaving nine tritor rods visible
edge of the lingual surface is strongly abraded, leaving nine
that lay against the labial surface and additionally five mesial
small mesial, one large central and four smaller tritor rod vis
ones. The narrow, smooth distal section is slightly concave
ible that lay against the labial surface. The central tritor rod is
and interlocks with the palatal tooth plate.
merged the large tritor pad that supports the central ridge.
PALATAL TOOTH PLATE
The plate is triangular. The mesial margin is slightly arched
Genus: Rhinochimaera GARMAN 190 I and joins the lingual margin in a rounded angle. The slightly
arched lingual margin joins the labial one in a sharp angle of
This genus comprises the three extant species (DIDIER, about 20_. The lingual and mesial mm·gins join in an angle of
1995) R. atlantica, R. africana and the type species R. about 30_. The labial surface is bent from the labial margin
pacifica. Lacking sufficient material of the type species, R. towards lingual margin. The concave lingual surface is
atlantica was used for description and illustration. smooth and bent from the labial margin toward lingual mar
gin. Tritor rods and tritor pads are absent.
MATERIAL
The following 14 specimen of 2 species were examined: MANDIBULAR TOOTH PLATE
The plate is triangular. The mesial margin is straight and
Rhinochimaera atlantica joins the lingual margin in a rounded angle. The lingual mar
Coli. Herman <j> 120 em tl. gin joins the labial one in a sharp angle of about 30_. The
Coil. Hennan <j> 125 em tl. lingual and mesial margins join in an angle of about 30_. The
Coil. Herman <j> 135 em tl. labial surface is bent from the labial margin toward lingual
Coil. Herman <j> 139 em tl. margin. The concave lingual surface is smooth and bent from
Coli. Herman 0 100 ern tl the labial margin toward lingual margin. Tritor rods and tritor
Coil. Hovestadt 0 I 00 ern tl. pads are absent.
Coli. Hovestadt 0 100 em tl.
Coil. Hovestadt 0 100 em tl. The dorsal fin spine possesses one sharp mesial ridge that
Coli. Hovestadt 0 I 00 ern tl. diminishes in height toward the apex.
CoiL. Hovestadt <j> 120 ern tl. The distal face is a relatively shallow, broad central fun·ow.
I I
12 J. HERMAN, M. HOYESTADT-EULER & D.C. HOVESTADT
Its lateral margins bear minute tubercles, with their tips DORSAL FIN SPINES
downturned, along the spine's lower half. The lateral sur-· Although such material of Neoharriotta was lacking, signifi
faces are convex in cross-section. The interior part of the cant intergeneric differences were noted in the other genera.
spine is hollow. Generally, the dorsal fin spine has a central ridge at the me
sial face and convex lateral faces. Callorhinchus, Harriotta
FRONTAL TENACULUM DERMAL DENTICLES and Rhinochimaera share a mesial central ridge and convex
The frontal tenaculum bears approximately 80 dermal lateral faces. They can be distinguished by the distal spine
denticles on its bulbous distal part, arranged in a patch of ten face. Callorhinchus possesses tubercles with downturned
more or less regular longitudinal rows. The size of the tips at both lateral margins of spine's the upper third part,
denticles diminishes toward tenaculum's sides. Each denticle Harriotta possesses tubercles with downturned tips at both
consists of a more or less flat, semi-oval, radiated basal plate lateral margins of spine's the upper two-third part, and
with a hook-like cusp on top. The basal face of each dermal Rhinochimaera possesses hardly perceptible tubercles at the
denticle is funnel shaped with a central aperture. lateral margins of the lower spine part. The mesial spine face
Cutting edges on elongated arched cusps are absent and sur of both Chimaera and Hydrolagus possesses three sharp, dis
faces are smooth. tinct, mesial ridges, of which at spine's base the central one is
approximately three times higher than the lateral ones. The
distance at spine's base between the central ridge and each
Differential diagnosis
l.~.teral ridge almost equals the height of the central ridge but
narrows as the spine tapers toward its apex. The height of the
TOOTH PLATES
central ridge diminishes toward the apex, and the three ridges
Although some extinct species have a different configura
join to become one ridge close to the apex. The central ridge
tion, the six extant chimaeroid genera all possess a pair of
of Chimaera is smooth, whilst in Hydrolagus it has tubercles
vomerine and palatal plates in the upper jaw and a pair of
with upturned tips at spine's lower part. The upper distal
mandibular plates in the lower jaw.
spine face of both possesses tubercles with downturned tips
The most significant morphologically distinctive features of
on the lateral margins of the spine.
the genera are summarized in table I.
The tooth plate morphology of Rhinochimaera differs
FRONTAL TENACULUM DERMAL DENTICLES
strongly from the remaining five genera by the extraordinary
The frontal tenacula of Callorhinchus, Rhinochimaera,
shape of vomerine, palatal and mandibular tooth plates. The
Harriotta, Chimaera and Hydrolagus are similar. They con
palatal and mandibular plates have one sharp, more or less
sist of a cartilaginous appendix at the skull's fore head which
straight labial margin, without any indentation between tritor
bears an oval- to circular-shaped patch of dermal denticles at
rods and tritor rods, and tritor pads are absent on vomerine,
the tip. The denticles are more or less an·anged in semi-paral
palatal and mandibular plates.
lel rows. The numbers of rows, as well as the number of
Callorhinchus is distinguished from Chimaera, Hydrolagus,
denticles within a row vary in each genus. Each denticle con
Harriotta and Neoharriotta by a vomerine plate with a single
sists of a more or less flat, semi-oval, radiated basal plate
mesial tritor rod only, a palatal plate with a single bifurcated
with a hook-like cusp on top. The basal face of each dermal
tritor pad and a mandibular plate with a single semi-circular
denticle is funnel shaped with a central aperture. The elon
tritor pad. Further, the palatal and mandibular plates have a
gated, curved cusps of the dermal denticles of Chimaera and
unique deep depression on the labial surface.
some of Hydrolagus have a central and two lateral cutting
There are no significantly morphological differences be
edges and smooth surfaces. Those of Harriotta only possess
tween Chimaera and Hydrolagus. However, both can be dis
lateral cutting eoges. Examined specimens of male of
tinguished from Harriotta and Neoharriotta by a vomerine
Callorhinchus present an opposite additionnal patch of
plate with a low number of tritor rods (five) and a lingual
denticles fixed on the skull, fanning a tenacular complex.
surface with well-developed horizontal ridges; further by a
Material of Neoharriotta was not available, but illustrated
palatal plate with six distal and five mesial tritor pads and a
male specimens in the scientific literature are only in posses
mandibular plate with six distal and a single mesial tritor rod.
sion of a common frontal tenaculum.
Both Harriotta and Neoharriotta lack horizontal ridges on
the lingual surface of the vomerine plate. However,
Harriotta has a vomerine plate with up to ten tritor rods with Conclusions
the most mesial one forming a hook-like extension, whilst
that of Neoharriotta has nine distal anci five mesial tritor rods Concerning the tooth plate morphology, Rhinochimaera dif
and lacks a hook-like extension. Their palatal plates differ, in fers severely from all other chimaeroid taxa. Among the re
that Harriotta has seven small plus a large mesio-mid tritor maining taxa, Callorhinchus shares some general characters
pad, whereas Neoharriotta shows up to ten small distal, a like having tritor rods and tritor pads but has unique charac
central and three smaller mesial tritor rods. Further, teristic features separating it from the other taxa (see differ
Harriotta and Neoharriotta can be distinguished by their ential diagnosis). Harriotta share more characters with the
mandibular plates, on which Harriotta has five distal and remaining taxa than Callorhinchus but has an unique shaped
three larger tritor rods, whereas Neoharriotta has up to ten vomerine plate. Neoharriotta, Chimaera and Hydrolagus
small distal, a large central and four smaller mesial tritor share many characteristic features, and the latter two cannot
rods. be separeted by tooth plate morphology.
I I
Contributions to the study of the comparative morphology of teeth and other relevant ichthyodorulites 13
Species Vomerine plate Palatal plate Madibular plate
Cal/orhinc!ms -A single mesial tritor rod -One large bifurcated -One large semi-
-Main lingual surface tritor pad circular tritor pad
smooth -Deep depression at the -Deep depression at the
labial surface labial surface
Chimaera -Five or six tritor rods -Six distal and five -Six distal and one :·
-Main lingual surface with larger mesial tritor pads larger mesial tritor rod
well developed horizontal -Short or lacking distal -Lingual central ridge
ridges margin supported by a large
tritor pad
Harriotta -Up to ten tritor rods with the -Seven distal and one -Five distal and three
mesial one .w.ith a hook-like large mesio-mid tritor larger mesial tritor rod
extension pad -Lingual central ridge
-Main lingual surface -Short distal margin supported by a large
smooth tritor pad
Hydrolagus -Five or six tritor rods -Six distal and five -Six distal and one
-Main lingual surface with larger mesial tritor pads larger mesial tritor rod
well developed horizontal -Short distal margin -Lingual central ridge
ridges supported by a large
tritor pad
Neoharriotta -Nine labial and five mesial -Up to ten small distal, -Up to ten small distal,
tritor rods one large central and one large central and
-Main lingual surface three smaller tritor rods four smaller tritor rods
smooth -Lingual central ridge -Lingual central ridge
supported by a large supported by a large
tritor pad tritor pad
-Labial surface smooth -Labial surface smooth
Rhinochimaera -Tritor rods absent -Tritor rods absent -Tritor rods absent
-Main lingual surface -Main lingual surface -Main lingual surface
smooth smooth smooth
-Central ridge absent -Central ridge absent
-Sharp, straight cutting -Sharp, straight cutting
edge edge
Table I
Concerning the type of character differences, the following also whould like to thank Captain P. GUEGUEN for allowing
hypothetical phylogenetic intenelationships can be given and helping us to collect specimens and S. MAILLIOT (Uni
(see textfigure 2): Chimaera and Hydrolagus cannot be dis versity Claude Bernard, Lyon, France) for the gift of a
tinguished and could be considered congeneric. Harriotta specimen.
Rhinochimaera is clearly different from all other taxa. The
remaining taxa Harriotta, Chimaera!Hydrolagus and
Neoharriotta may form a subgroup in which Harriotta Bibliography
clearly distinguishes.
DIDIER, D.A. 1995. Phylogenetic Systematics of Extant
Dorsal fin spine morphology indicates a closer relationship Chimaeroid Fishes (Holocephali, Chimaeroidei). Novitates, Ameri
can Museum of Natural HistOJ)', 3119: l-86.
of Harriotta, Rhinochimaera and Callorhinchus and a sepa
ration of these genera from Chimaera and Hydrolagus. PATTERSON, C. 1992. Interpretation of the tooth plates of
Neoharriotta cannot be interpreted due to lacking material. chimaeroid fishes. Zoological lou mal of the Linnean Society, l 06
(I): 33-61.
Frontal clasper morphology presents too little character vari STAHL, B.J. 1999. Chondrichthyes III Holocephali. In: Handbook
ation for distinguishing externally between the genera. of Paleoichthyology Yol.4. Gustav Springer Verlag, Stuttgart: 164
pp.
Acknowledgments
Additional references
The authors thank Dr. G. LENGLET and his assistant Mr. G.
COULON, Institut Royal des Sciences Naturelles de Belgique, BIGELOW, H.B. & SCHROEDER, W.C. 1953. Fishes of the West
Brussels for giving access to specimens at his disposal, Dr. ern North Atlantic, Memoir Sears Foundcaionfor marine research,
DIDIER-SAGIT and Mr. M. SABAJ, National Academy of l. part 2: 515 -562.
Natural Science, Philadelphia for the loan of specimens and DEAN, B. 1904. Notes on the long-snouted chimaeroid of Japan,
Dr. M.-H. DUBUIT, College de France, Laboratoire de Rhinochimaera (Harriotta) pacifica. Journal of the College of
Biologie Marine, Concarneau for providing specimens. We Science of the Imperial University ofTokyo 19.4: 20 pp.
Triter rods and tritor pads absent
Rhinochimaera -!'>
!-
;:r:
:tT:0l
3:::
_z)>
Chimaeridae
Vomerine· plate with a single mesial tritor rod
3:::
Vomerine, palatal and Palatal and mandibular plate with one semi-cicular tritor pad and no tritor rods ;:r:
0
Callorhinchus I
mandibular tooth plates present til
(/)
):!
.0... ,
Vomerine plate with an extended rr,
c
hook-shaped mesial tritor rod r
tTl
Harriotta 1::0
Ro
Triter rods or Palatal plate with a singel tritor pad 0
0
tritor pads present ;:r:
0
<
Vomerine, palatal and
tTl
(/)
madibular plates with ):!
Neoharriotta I~
Vomerine plate with several tritor rods
more than 13 tritor rods
Palatal and mandibular plate with several Vomerine plate with a non-
tritor rods or tritor pads hook-shaped mesial tritor rod
Palatal plate with
Vomerine, palatal and
several tritor pads
madibular plates with
Chimaera/Hydrolagus
less than 13 triter rods
Text figure 2