A New Genus Of Fossil Pufferfish (Tetraodontidae, Tetraodontiformes) Based On A New Species From The Oligocene Of Russia And A Referred Species From The Miocene Of Ukraine

12 Pages·1994·3.9 MB·English

by  J C Tyler

PROC. BIOL. SOC. WASH.
107(1), 1994, pp. 97-108
A NEW GENUS OF FOSSIL PUFFERFISH
(TETRAODONTIDAE: TETRAODONTIFORMES) BASED
ON A NEW SPECIES FROM THE OLIGOCENE OF
RUSSIA AND A REFERRED SPECIES FROM
THE MIOCENE OF UKRAINE
James C. Tyler and Alexandre F. Bannikov
Abstract.—A newgenus oftetraodontid pufferfish, Archaeotetraodon, is pro-
posed for two fossil species with uniquely specialized bifurcate scale spinules:
winterbottomi, a new species based on ten specimens from the Oligocene of
Russia in which nearly all ofthe spinules are bifurcate; andjamestyleri Ban-
nikov (1990), based on two complete specimens and a fragment from the
Miocene ofUkraine in which only two scales in the middle ofthe body have
bifurcate upright spinules. An especially long rayless pterygiophore extending
forward from the dorsal-fin origin inArchaeotetraodon (in winterbottomi; con-
dition unknown injamestyleri) is similar to that found in the Recent Lago-
cephalus but this feature cannot be unequivocally polarized and may not in-
dicate relationship between these two genera.
Expeditions by the Paleontological Insti- raodontids based on relatively entire spec-
tute ofthe Russian Academy ofSciences to imens shows that one ofthem, Sphoeroides
the North Caucasus have discovered a rich jamestyleriBannikov(1990), fromtheMio-
LowerOligocenemarineichthyofaunainthe ceneofUkraine, hasmostofthe scaleswith
Pshekhsky Horizon of the Lower Maikop unbranchedspinulesbutthatalimitedpatch
deposits. This was first describedby Danil- in the middle ofthe body has bifurcate spi-
chenko (1960), with further studies more nules. We transfer S. jamestyleri from
recentlyby the second listed authorand his Sphoeroides, into which it was originally
cooperating colleagues. Among newly ex- placed mostly for the convenience of not
cavated fossils of early Oligocene age are havingtocreateanewgenus,toArchaeotet-
ten specimens, four in counterpart plates, raodon on the basis ofits sharing with A.
that are unique among tetraodontids by winterbottomi specialized bifurcate scales.
having most of the upright scale spinules The two species oiArchaeotetraodon differ
that cover the entire body bifurcate from from one another not only in the coverage
the base and divergent distally. The bifur- with bifurcate scales but also in several os-
cate scale condition is shown to be a spe- teological features.
cialization because all Recent and one of
the other fossil tetraodontids as well as all Methods
membersofthediodontid sistergrouphave
undivided upright scale spinules. We de- Lengthisstandardlength(SL)unlessoth-
scribethese specimensas anewspeciesand erwise stated. Fossil materials are from the
type ofanewgenus: Archaeotetraodon win- collections of the Paleontological Institute
terbottomi. (PIN) ofthe Russian Academy ofSciences
Our re-examination ofthe scales in ma- in Moscow, the Museo Civico di StoriaNa-
terials ofall previously described fossil tet- turale di Verona (MCSNV), the Istituto di
98 PROCEEDINGSOFTHE BIOLOGICAL SOCIETY OFWASHINGTON
Geologia della Universita di Padova pleural ribs (both ofwhich are found in tri-
(IGUP), and Sammlung der Philosophie- odontids); however, because diodontids and
theologie HochschulederEichstatt(SPHE). molids have no pleural ribs and fewer than
Comparative anatomical preparations and twelve caudal-fin rays, it is more parsimo-
radiographs ofRecent species oftetraodon- nious to propose that the twelve caudal-fin
tiformsarethoselistedinTyler(1980), sup- rays and pleural ribs ofEotetraodon are re-
plemented by those oftetraodontids listed versals.
in Tyler et al. (1992). Althoughitwasinconsistentwithhispre-
In many derived groups of tetraodonti- sumed phylogeny of tetraodontid genera,
forms, including tetraodontids, there is a Tyler (1980) continued the practice ofrec-
bony element in the upper midline of the ognizing Canthigaster as subfamilially dis-
bodyjust in front ofthe soft dorsal fin that tinct from other tetraodontids even though
isthoughttorepresentabasalpterygiophore thegenus Carinotetraodonwas shown to be
that no longer bears dorsal-fin spines. This anatomicallyintermediatebetween Canthi-
was called a supraneural in Tyler (1980), gasterandothertetraodontidsinmanyways,
but is here referred to as a rayless pteryg- including several specialized features (e.g.,
iophore, following the recommendation of skin ridge-lifting behavior, highly arched
Mabee (1988:836), who demonstrated that vertebral column, large haemal spines on
true supraneurals (predorsals) are not ho- abdominalvertebrae). ThisledTyler(1980)
mologous with such pterygiophores. to the conclusion that Carinotetraodon and
For tetraodontoid phylogeny we follow Canthigasterhadaclosecommonancestry.
the cladistic analysis of Winterbottom Therefore, we agree with Winterbottom
(1974) and the evolutionary systematics of (1974:99) that Canthigastercannot reason-
Tyler(1980), which, respectively ontheba- ably be recognized as subfamilially distinct
sis ofspecialized myological and osteolog- from (and sister group to) a polyphyletic
ical features, are in agreementthat: diodon- subfamily for all other tetraodontids, in-
tids are the sister group of tetraodontids; cluding Carinotetraodon. With the phylog-
molidsarethe sistergroupofthetetraodon- enyoftetraodontidgenerasopoorlyknown,
tid + diodontid clade; triodontids are the we compare any unusual features of Ar-
sistergroupofthetetraodontid + diodontid chaeotetraodonwithcomparableconditions
+ molid clade; and the Eocene eoplectids in all other tetraodontid genera, including
are the morphologically primitive sister thespecialized Canthigaster + Carinotetra-
group of all of these other tetraodontoids. odoncladetowhichwedouhXArchaeotetra-
Among other tetraodontiforms, the balis- odon is closely related.
toid + ostracioid clade is the first outgroup
and the triacanthoid clade the second out-
Family Tetraodontidae (sensu Tyler, 1980)
group.
Archaeotetraodon, new genus
Thereisnocladisticanalysisavailablefor
thegeneraoftetraodontids,andTyler(1980) Type species.—Archaeotetraodon winter-
simply placed the Recent genera into three bottomi, new species, by present designa-
groups ofrelative degrees ofmorphological tion; other species, Sphoeroidesjamestyleri
specialization in what can be considered an Bannikov (1990), by referral herein.
unresolved trichotomy. The Eocene Eotet- Diagnosis.—Y^'i^Qrs from all other tetra-
raodonwas presumed in thatworkto bethe odontids by the presence of bifurcate up-
morphologically primitive sister group of right spinules on either most of the scale
these threegroupsofRecentgenerabecause plates over the entire body (in winterbot-
of its retention of such plesiomorphic fea- tomi) or on many ofthose ofthe middle of
turesastwelveprincipal caudal-finraysand the body (injamestyleri).
VOLUME NUMBER
107, 1 99
Description.—Withtheexceptionofafew forthe tetraodontid + diodontid clade and
species in which scales have been second- thatthedeeplybifurcatespinulesintheOli-
arily lost (several species of both Sphoe- gocene A. winterbottomi and Miocene S.
roides and Takifugu and single species of jamestyleri are a specialization. Therefore,
both Lagocephalus and Tetraodon; Tyler the bifurcate spinule condition is a syna-
1980:297-298) all Recent tetraodontids pomorphy of A. winterbottomi and S.
have specialized scales in which the basal jamestyleri. The latterwas originally placed
plate, which has two or more processes ra- in Sphoeroides because it is thought to be a
diating out into the skin, bears an upright morphologically relatively primitive genus
spinule that protrudes through the skin as (Tyler 1980) defined by a combination of
aprickle. Thespinuleisofvaryingstoutness what seem to be mostly plesiomorphic fea-
andlength,butmostoftenisshortandslen- tures, and no features that are known to be
der (in contrast to the larger and stouter specialized. It was simply convenient to
projecting spines in diodontids), giving a place S. jamestyleri in that poorly defined
shagreen-like quality to the skin (see illus- genus pending acquisition of better pre-
trations of scales in Recent species of nu- servedmaterialsshowingmoreinternalfea-
merous tetraodontid genera in Tyler 1980: tures which might clarify its relationships,
291-297). but such materials are not yet available.
Thatthenewspeciesoftetraodontidfrom However, we can state that all of the few
the Oligocene, A. winterbottomi, has an ex- known internal features of similarity be-
tensive covering ofbifurcate scale spinules tween S. jamestyleri and the species of
led us to re-examine the scales in the two Sphoeroides are plesiomorphic (e.g., mod-
previously described species offossil tetra- erateinterorbitalandethmoidwidths;mod-
odontids based on relatively entire speci- erate and mostly laterally directed exten-
mens, the Eocene Eotetraodon pygmaeus sions of the lateral ethmoids, sphenotics,
(Zigno 1887) and the Miocene Sphoeroides and pterotics) and that there are no known
jamestyleri Bannikov (1990). The holotype specialized features ofsimilarity that unite
and four other previously unreported spec- 5.jamestyleriwith Sphoeroides. Because S.
imens of£. pygmaeusare coveredwith un- jamestyleridoes share the uniquely derived
branched spinules like those of all Recent feature of bifurcate scale spinules with A.
tetraodontids. The holotype ofSphoeroides winterbottomi, we remoYejamestyleri from
jamestyleri does not have the scales pre- Sphoeroides and place it in Archaeotetra-
served, but the paratypic entire specimen odon along with winterbottomi.
has a complete covering ofscales, most of We note that in molids the basal plates
whichhaveunbranchedspinules. However, ofthe scales are rounded to rectilinear and
some scales in the middle ofthe body (it is bear a central emargination or low spinule,
impossible to distinguish whether this is and in at least smaller specimens ofMala
dorsal, ventral, or lateral) are just as dis- someofthesespinulesarebrancheddistally
tinctly bifurcate distally as those inA. win- (see illustration in Tyler 1980:369). In all
terbottomi, although the spinules are pro- other tetraodontoids with upright spinules
portionally shorter in S. jamestyleri. on the basal plate, the spinules are un-
Because all species, both fossil and Re- branched (a single spinule in eoplectids, the
cent,ofthediodontidsistergrouphavescale sistergroup ofall othertetraodontoids, and
plates with unbranched upright spinules or several spinules in the poorly known zig-
spines like those of all Recent and one of noichthyids, thataremostcloselyrelatedto
the fossil species of tetraodontids (except the tetraodontid -I- diodontid clade). In tri-
more massive), we propose that spinules odontids the scales bear a low spiny ridge
with undivided upright shafts are primitive and there are no upright spinules. There-
100 PROCEEDINGSOFTHE BIOLOGICALSOCIETYOFWASHINGTON
fore, on the basis ofthe phylogeny oftetra- to it and articulates there with an anterior
odontoid families proposed by both Win- process on the distal end ofthe first basal
terbottom(1974)andTyler(1980), itismost pterygiophore ofthe dorsal fin. We see no
parsimonious to presume that the distally evidence ofsuch an anteriorprocess on the
branched spinules in some molids and the first basal pterygiophore in Archaeotetra-
deeply bifurcate branched spinules in Ar- odon, but that pterygiophore is notwell ex-
chaeotetraodon are independent acquisi- posed in our material. Although we cannot
tions. be absolutely sure ofit, we have no reason
Etymology.—From the Greek: archaios, to believe that the rayless pterygiophore in
old or ancient, and tetraodon, for the four Archaeotetraodon does not extend as a sin-
toothplatescharacteristicofthefamilyTet- gle slender bone for the full length of the
raodontidae; masculine. distance from itsanteriorendto the dorsal-
fin origin. Nevertheless, it is possible that
some small portion ofour measurement of
Similarities oiArchaeotetraodon to
the rayless pterygiophore posteriorly inAr-
Other Tetraodontids
chaeotetraodon mayinclude part ofthe dis-
Rayless pterygiophore. —Archaeotetra- tal head ofthe first basal pterygiophore of
odonwinterbottomihasanexceptionallylong the dorsal fin. Even with that caveat, we
rayless pterygiophore, averaging 18% SLas believe that the average measurement of
measured from the anterior end ofthe el- 18% SL is a fair estimate ofthe length of
ementto the anteriorend ofthe base ofthe the rayless pterygiophore in Archaeotetra-
soft dorsal fin in the three specimens in odon. No other tetraodontid has a rayless
whichthisregion ispreserved. We presume pterygiophoreas longasthatinArchaeotet-
that this long slender element is a single raodon, but a few genera contain species
piece ofbone from its posterior end at the with rayless pterygiophores almost as long.
dorsal-fin origin to its anterior end at the The rayless pterygiophore is especially
level ofthe vertical through the centrum of long and slender in the six species of La-
the sixthto seventh abdominalvertebrabe- gocephalusexamined, moresoinsomespe-
cause we cannot see any interruptions or ciesthan in others. Forexample, inL. iner-
articulations in it, although ourview ofthe mis (Temminck & Schlegel), L. laevigatus
bone is somewhat obscured by the layer of (Linnaeus), L. lunaris (Bloch & Schneider),
spiny scales in the overlying skin. In the and L. spadiceus (Richardson) the rayless
holotype of^. jamestyleri the region ante- pterygiophore length averages 8-9% SL (in
rior to the dorsal fin is poorly preserved, 2 to 12 specimens of each species exam-
while in the paratypic entire specimen the ined), whileitaverages 12% SLinL. sclera-
skeletonis muchdisarticulatedanditis not tus (Gmelin) (in 4 specimens) and 15% SL
possible to recognize a rayless pterygio- in L. lagocephalus (Linnaeus) (in 2 speci-
phore among the mixture ofbones. Thus, mens), the latter being the longest rayless
the condition of the rayless pterygiophore pterygiophoreofwhichweareawareamong
inA.jamestyleriis unknown and in the fol- Recent tetraodontids. In all ofthese species
lowing discussion of the rayless pterygio- ofLagocephalus the distal end of the first
phore the statements about Archaeotetra- dorsal-fin basal pterygiophore has a prom-
odon are based on the conditions in A. inent anterior process to which the rayless
winterbottomi. pterygiophore articulates. The rayless pte-
In some Recent tetraodontids with rela- rygiophore of Lagocephalus, even though
tively long rayless pterygiophores, this ele- shorter than in Archaeotetraodon, extends
ment does not reach posteriorly to the dor- at least as far forward as in Archaeotetra-
sal-finoriginbut,rather,terminatesanterior odon. and, in L. lagocephalus, extendseven
VOLUME 107, NUMBER 1 101
further forward, to the level ofthe vertical Inthemolidsistergroupofthetetraodontid
through the region ofarticulation between + diodontidcladetheraylesspterygiophore
thecentraofthe fourthand fifth abdominal iseitherpresentasashortdeeppiece(Mola),
vertebrae. Thetwo species ofLagocephalus absent or fused with the first basal pteryg-
with the longest rayless pterygiophores, L. iophore ofthe soft dorsal fin (Masturus), or
scleratus and L. lagocephalus, are stream- perhaps consolidated into a long complex
lined in form and have an offshore pelagic structure that connects the first basal pte-
habitat; there may be a correlation in tetra- rygiophore of the soft dorsal fin with the
odontidsbetweenalongand slenderrayless supraoccipitalcrest(Ranzania). Intriodon-
pterygiophore and a strong swimming, pe- tids a rudimentary spiny dorsal fin, when
lagic mode oflife. present, oftwo or three spines is borne on
The rayless pterygiophore is relatively twobasalpterygiophoresthatareconnected
long in the nine species ofCanthigasterex- tothebasalpterygiophoresofthesoftdorsal
amined,averagingbetween9%and 13%SL. finbytwoshortraylesselements. Thesetwo
The rayless pterygiophore of Canthigaster shortelementspresumedlyarederivedfrom
differs from the slender rod as found inAr- basal pterygiophoresthatno longersupport
chaeotetraodon and Lagocephalus in being spines at the rear ofthe rudimentary spiny
heavier, deeper, concave ventrally, and dorsal fin. In those populations (Indian
curved ventrally at its anterior end, follow- Ocean)ofTriodon macropterus(Lesson)(the
ing the contour ofthe arched back. only Recent representative of the family)
InmostspeciesofSphoeroidestherayless that usually entirely lack the spiny dorsal
pterygiophore is short, averaging about 4- fin,allfouroftheelementsinthisseriesthat
5% SL, but the element is somewhat longer extends anteriorly from the soft dorsal-fin
in such species as S. spengleri (Bloch) and origin therefore are rayless pterygiophores,
S. marmoratus(Lowe), averaging 6-7% SL. the first ofwhich is elongate and the more
In 5'. formosus (Gunther) (sometimes rec- posterior three pieces short. In eoplectids a
ognizedinthe monotypic Guentheridia)the well-developed spiny dorsal fin is present
rayless pterygiophore is far longer, heavier, and its basal pterygiophores connect with
and deeper than in the other species of those ofthe soft dorsal fin without the in-
Sphoeroides, averaging 12% SL (in 5 spec- terventionofraylesspterygiophores. Among
imens) but without the slender form found the outgroup tetraodontiforms, the six dor-
in Lagocephalus and Archaeotetraodon. sal-fin spines in triacanthoids are borne on
Otherthan the species mentioned above, four or five basal pterygiophores and there
weknowofno othertetraodontidswith no- are no rayless pterygiophores between the
tablylongraylesspterygiophores,i.e.,of10% basal pterygiophores ofthe spiny and soft
SL or greater length. The condition ofthe dorsal fins. In balistids the three dorsal-fin
rayless pterygiophore in a variety oftetra- spines are borne on two basal pterygio-
odontids can be assessed from the illustra- phores that form a complex carina sup-
tions of representative species in Tyler portedbyaraylesspterygialstrutthatbraces
(1980:figs. 195, 203, 226-244),includingits the carina against the first basal pterygio-
absence in a few species. phore of the soft dorsal fin, with the strut
The similarity in the length ofthe long, apparentlybeingderivedfromthethirdbas-
slender rayless pterygiophore between Ar- al pterygiophore ofthe spiny dorsal fin of
chaeotetraodon and some species ofLago- triacanthoids.Inmonacanthidstherearetwo
cephalus is difficult to interpret because of dorsal-fin spines, andthelessrobustcarina,
the unknown phylogeny within tetraodon- which is formed from a single basal pteryg-
tids and because diodontids, their sister iophore, is not supported posteriorly by a
group, do nothave a rayless pterygiophore. pterygial strut. In ostracioids the spiny dor-
102 PROCEEDINGS OFTHE BIOLOGICALSOCIETY OFWASHINGTON
sal fin is absent and a long and deep (ara- rygiophore of those Triodon macropterus
canids) or short (ostraciids) rayless pteryg- lacking dorsal-fin spines as it could be one
iophoreispresentanteriortothebaseofthe ofthe three short and heavy more posterior
soft dorsal fin. Thus, when the spiny dorsal raylesselements. We havenowayofknow-
fin is absent in tetraodontiforms such as os- ing at present whether the rayless pteryg-
tracioids, raylesspterygiophoresarepresent iophoreintheancestraltetraodontoidwith-
and apparently represent basal pterygio- out a spiny dorsal fin was long or short.
phores ofthe absent spiny dorsal fin, while Therefore, similarityinthelongraylesspte-
thereductioninnumberofdorsal-fin spines rygiophore oiArchaeotetraodon and Lago-
and their supporting basal pterygiophores cephalus may be plesiomorphic and notin-
from posteriorly in the series in balistids in dicative ofrelationship.
comparison to triacanthoids is accompa- Our surmise is that the great length and,
niedbytheapparentconversionofthethird especially, the slender form of the rayless
basal pterygiophoreoftriacanthoidsintothe pterygiophoreisaderivedfeature,butsince
rayless pterygial strut ofbalistids. we do not know of any unequivocally de-
Most germane, however, is the situation rived features shared by Archaeotetraodon
in triodontids, the sister group ofall other and Lagocephalus, it may be that the pu-
Recent families oftetraodontoids, in which tatively derived condition ofthe long, slen-
the distinction between basal pterygio- der rayless pterygiophore is independently
phores and rayless pterygiophores depends acquired by these two genera. From what
simply on whether the rudimentary dorsal- little is known ofits osteology, Archaeotet-
fin spines are present or not. Therefore, we raodondiffersfromLagocephalusin having
propose that the presence ofa rayless pte- relativelyevenlytaperedneuralandhaemal
rygiophore, representing a rudimentary spines on the vertebrae of the caudal pe-
support ofthe now absent spiny dorsal fin, duncleanteriortothepenultimatevertebra,
is primitive forthe tetraodontid + diodon- whereas in Lagocephalus these are expand-
tid + molid clade oftetraodontoids. How- ed anteroposteriorly, a derived condition
ever, it is equally parsimonious to hypoth- (absentinothertetraodontidsandinalloth-
esize that: 1) a rayless pterygiophore was er tetraodontoids).
present in the ancestor ofthe tetraodontid Elongate head spines.—In at least one
+ diodontid clade and that the rayless pte- specimen of Archaeotetraodon winterbot-
rygiophore was independently lost by all tomithe spinules on the top ofthe head are
diodontids and by some tetraodontids; or longerthanelsewhereandmanyoftheseare
2) a rayless pterygiophore was lost in the not bifurcate. In only one other species of
ancestor of the tetraodontid + diodontid tetraodontid are the spinules on the head
clade and the rayless pterygiophore ac- much longer than those on the body, this
quired by most tetraodontids as a reversal being one ofthe several species ofAmbly-
to the ancestral tetraodontoid condition. rhynchotes, A. piosae. In A. piosaethe body
Moreover, even given that a rayless pteryg- is made exceptionally prickly by spinules
iophore is primitive for the tetraodontid + that are longer than in other tetraodontids,
diodontid + molid clade, it is not known and the spinules on the top and side ofthe
whether that element was long or short or front ofthe head are especially elongate, up
slender or stout. Presuming that the rayless to 8% SL. These spinulesare proportionally
pterygiophore of the ancestral tetraodon- far longer than those that are slightly elon-
toid without a spiny dorsal fin was one of gate on the top ofthe head in A. winterbot-
the four dorsal pterygial elements as found tomi. In both cases among tetraodontids in
in triodontids, it could as logically be the which speciose genera have a few species in
long, stout, anteriormost first rayless pte- which spiny scalesare lost, these speciesare
VOLUME 107, NUMBER 1 103
not considered to be closely related within basis ofpieces ofjawbones ofMiocene and
their respective genera {Sphoewides and younger age but these cannot be usefully
Takifugu) and the loss of spines has been compared with the fossil species based on
considered to be independent (Tyler 1980: more complete specimens.
297). With so much homoplasy in even the We can only call attention to the unique
presence or absence ofspines within tetra- bifurcate scalesthatdistinguishArchaeotet-
odontid genera, we place no phylogenetic raodon from all other genera oftetraodon-
significance on the fact that both one spec- tids and note that while the elongate and
imen of A. winterbottomi and one of the slenderrayless pterygiophoreas foundinA.
severalspeciesofAmblyrhynchoteshavethe winterbottomiand some Lagocephalusmay
spinules longer on the head than elsewhere, beaspecializationforapelagicmodeoflife,
especially when the spinules in A. winter- it seems likelyto havebeenan independent
bottomi are otherwise so different (shorter acquisition in the fewpelagic species ofLa-
and bifurcate) than those in A. piosae, and gocephalus and in A. winterbottomi, which
when there are no other derived features of has been found in a predominantly pelagic
similarity between Archaeotetraodon and fossil ichthyofaunal assemblage.
any ofthe species oiAmblyrhynchotes. Ar-
chaeotetraodon differs from Amblyrhyn-
Archaeotetraodon winterbottomi,
chotes not only by its short bifurcate scales new species
but most notably also by having 18 versus Figs. 1-4
19 or 20 vertebrae (in the three species of
Amblyrhynchotesexamined)andalong(18% Diagnosis.—Archaeotetraodonwinterbot-
SL) versus short rayless pterygiophore (5- tomi differs from the only other species of
6%SLinthreespeciesofAmblyrhynchotes). the genus, A. jamestyleri, by having: a ver-
tebral formula of 8+10 (versus 7+11 in
jamestyleri); almost complete covering of
Generic Relationships
bifurcatescalespinules(versusbifurcateonly
Onthebasisofitsfewknownosteological on middle ofbody); haemal spine ofpen-
andexternalfeatureswearenotabletoplace ultimate vertebra with a moderately long
Archaeotetraodonintooneofthethreemor- posteroventral process under the parhypu-
phologicalgroupsrecognizedbyTyler(1980) ral region (versus no prolongation); supra-
for Recent genera of tetraodontids. Like- cleithrum relatively long and narrow (ver-
wise, we do not find any special similarity sus shorter and thicker).
between the two species of Archaeotetra- Description.—'Body moderately elongate
odon and other fossil species oftetraodon- (Figs. 1-2). Vertebrae 18 in four specimens
tids. The Eocene Eotetraodon pygmaeus inwhich total numbercanbecounted, with
(Zigno) has neither bifurcate scales nor a eight abdominal and ten caudal in only
long rayless pterygiophore. The Pliocene specimen (holotype) in which proximal end
Sphoeroideshyperostosus(Tyleretal. 1992) offirst anal-fin basal pterygiophore can be
isbasedonskullsandanteriorvertebraebut seeninassociationwithahaemalspine;ver-
the scales and portions of the body that tebral column relatively straight, only gent-
might include a rayless pterygiophore are lyarchedinabdominalregion. Caudal skel-
unknown; it differs from Archaeotetraodon eton relatively distinct in holotype, and
bythe extensive hyperostosis ofmany skull havingnormaltetraodontidpatternofalong
bones at sizes as small as that ofthe larger parhypural, a lower hypural plate fused to
specimens of either of the two species of last centrum, an upper free hypural plate
Archaeotetraodon. Several other species of and an epural (exact shape unclear) above
fossiltetraodontidshavebeennamedonthe last centrum. Penultimate vertebra (PUj)
104 PROCEEDINGSOFTHE BIOLOGICALSOCIETY OF WASHINGTON
mm
Fig. 1. Photograph ofholotype ofArchaeotetraodon winterbottomi, PIN 3363/111, 90.0 SL, Lower
Oligocene(Maikopian)ofNorth Caucasus, southwest Russia.
with broad neural and haemal spines, the pterygiophores in dorsal fin seven and in
latter prolonged posteriorly under a little analfinsixinsinglespecimeninwhichthese
morethanhalfoflengthofparhypural; more can be counted. Caudal-fin rays 1 1 in four
anteriorcaudalvertebraewithmoreslender specimens, bestpreservedin holotype, with
neural and haemal spines, except haemal uppermost ray and two lowermost rays un-
spines offirst three caudal vertebrae short, branchedandothereightraysbranched,four
where proximal ends ofanal-fin basal pte- above middle ofhypural plate and four be-
rygiophores are supported. First three ab- low (typical tetraodontid condition). Cau-
dominal vertebrae apparently with bifid dal-fin length 23.3-27.3% SL (25.8% aver-
neural spines and fourth abdominal verte- age)inthreespecimens. Pectoralfinnotwell
bra with neural spine bifid anteriorly but enough preserved to describe.
undividedposteriorly,whereitisprolonged Asingleuprightspinulearisingfromeach
posteriorly overbase ofneural spineoffifth basal scale plate, spinules mostly short and
vertebra. divergently bifurcate from base (Fig. 3),
Dorsal-finraysnineintwospecimensand length ofupright spinulesalongtop ofmid-
nine or perhaps ten in one specimen. Anal- dle ofbody in nine specimens 0.7-1.6% SL
fin rays eight in only specimen in which all (1.3% average); these prickly scales present
rays are preserved, at least basally. Basal continuously over most ofhead and body.
example of scale covering
Fig. 2. Reconstruction oiAnhaeoletraodon winterbottomi. based on the holotype, dataas in Fig. 1.
VOLUME NUMBER
107, 1 105
Fig. 3. A. Photograph ofscales along dorsal surface ofparatype ofArchaeotetraodon winterbottomi, PIN
mm mm
3363/115, ca. 40 SL, longestuprightbifurcate spinules0.5 (1.3% SL), ageandlocalityas in Fig. 1. B.
Drawingofselectedscales alongsamedorsal surface as in A.
106 PROCEEDINGSOFTHE BIOLOGICALSOCIETY OF WASHINGTON
gentlycurved, with alow medial flange. In-
terorbitalwidth moderate, leastwidth about
4.0-4.5% SL in two entire specimens in
which it is possible to recognize the lateral
edges ofthe upper orbitin neurocrania pre-
served in dorsoventral view. No other fea-
tures ofskeleton clearly enough exposed or
preserved to warrant description.
—
Etymology. winterbottomi, honoringour
friend and colleague Richard Winterbot-
tom. Royal Ontario Museum, in recogni-
tion ofthe excellenceofhisimportant stud-
Fig. 4. Drawing ofinner surface ofpremaxilla of ies on the phylogeny of tetraodontiforms
holotype ofArchaeotetraodon winterbottomi, data as andofhisgreathelpto usin ourown efforts
in Fig. \. with the plectognath fishes.
Type materials.—YioloXypt: PIN 3363/
In one specimen (PIN 3363/120) a small 1 1 1 (head to left) and Ilia, counterpart
mm
group ofabout ten spinules on top ofhead plates. River Pshekha, 90.0 SL. Para-
slightly longer than those on body (1.4% types: PIN 3363/1 12 (head to right), single
mm
versus 0.9% SL) and mostly unbranched, plate. RiverBelaya, 53.9 SL; PIN 3363/
with all other spinules on head and body 1 13 (headtoleft), singleplate, RiverBelaya,
mm
bifurcate; we presume that having a few 36.5 SL; PIN 3363/1 14 (head to left)
slightlyelongate and non-bifurcate spinules and 1 14a, counterpart plates. RiverBelaya,
mm
on top ofhead is normal for at least some 27.8 SL; PIN 3363/115 (dorsoventral
specimensofthisspecies(perhapsasexually impression), single plate. River Belaya, ca.
mm
dimorphic feature). 40 SL; PIN 3363/116 (head to left),
Rayless pterygiophore long and slender, single plate. River Kuban, most of head
apparently a single piece, its posterior end missing, length of vertebral column 32.6
at origin of soft-dorsal fin and its anterior mm; PIN 3363/117 (head to left), single
end at level ofvertical through centrum of plate. River Pshekha, fragment ofmost of
sixth or seventh abdominal vertebra; its vertebral column, whose length is ca. 33
length 16.0-20.6% SL (18.1% average) in mm; PIN 3363/1 18 and 1 18a(dorsoventral
three specimens. impression), counterpart plates. River Be-
mm
Innersurface ofpremaxilla visible in two laya, 24.7 SL; PIN 3363/1 19 (head to
specimens, both ofwhich have three tritu- left)and 1 19a,counterpartplates. RiverBe-
mm
ration teeth, aboutthree times as mediolat- laya, 52.1 SL; PIN 3363/120 (head to
mm
erally wide as anteroposteriorly deep; me- right), single plate, River Belaya, 64.2
dial edge of premaxilla with articular SL. Except forthe two specimens preserved
processes increasing in size posteriorly in entirely as dorsoventral impressions, all of
series (Fig. 4), interdigitating with similar the above are preserved as lateral impres-
processesonapposedpremaxilla. Innersur- sions of the body in which, however, the
face ofdentary visible in one specimen and neocranium is often in dorsoventral view.
no trituration teeth present; medial edge of Type locality. —HoXoXyi^Q from River
dentary with articular processes like those Pshekha (at Gorny Luch). Paratypes from
ofpremaxilla. Rivers Pshekha, Belaya (upstream from the
Preopercle broad and strongly curved, settlement ofAbadzekhskaya), and Kuban
with ridges in middle region. Postcleithrum (near the town of Cherkessk), all ofwhich
long and slender. Supracleithrum long and sites are within, respectively, 32 and 150