450 

NOAA Technical Report NMFS Circular 450 

The Utility of Developmental 

Osteology in Taxonomic 

and Systematic Studies 

of Teleost Larvae: 

A Review 

Jean R. Dunn 

June 1983 

U.S. DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric Administration 

National Marine Fisheries Service 
E RT" 
NOAA Technical Report NMFS Circular 450 

The Utility of Developmental 

Osteology in Taxonomic 

and Systematic Studies 

of Teleost Larvae: 

A Review 

Jean R. Dunn 

June 1983 

U.S. DEPARTMENT OF COMMERCE 

Malcolm Baldrige, Secretary 

National Oceanic and Atmospheric Administration 

John V. Byrne, Administrator 

National Marine Fisheries Service 

William G. Gordon, Assistant Administrator for Fisheries 
The National Marine Fisheries Service (NMFS) does not approve, recommencl or endorse any proprietary product or proprietary material 

mentioned in this publication. No reference shall he made to NMFS, or 

to this publication furnished by NMFS, in any advertising or sales promotion which would indicate or imply that N;\lFS approves, recommends 

or endorses any proprietary product or proprietary material mentioned 

herein, or which has as its purpose an intent to cause directly or indirectly 

the advertised product to be used or purchased because of this NMFS 

publication. 
CONTENTS 

Introduction .......................................... .... ..... ... ........... ........ ... ......... . 

Methods of preparing larval fishes for skeletal study. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 2 

Skeletal structures of tel~ost larvae as taxonomic aids and systematic characters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 

Vertebral column and associated bones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3 

Fins and their supports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6 

Caudal fin ................................................. ......................... . ....... " 6 

Dorsal and anal fins . . . ............................................. . ..................... . .... . 6 

Pectoral fins and their supports . ......................................... . .............. ... ...... . 11 

Pelvic fins and their supports ..................................................................... 12 

Other skeletal structures ........................................................................... 12 

Branchiostegal rays .................................................................. . .......... 12 

Gill rakers and pharyngobranchial apparatus . .. .......... .... ......... ...................... . ........ 12 

Oromandibular teeth ............................................................................ 12 

Predorsal bones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 

Head spines and sculpturing .................................................................. .... 13 

Scales and lateral line pores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13 

Cranial bones ............................................. ... ............... . ..... . ... .. . .. . ... 13 

Examples of the use of developmental osteology in systematic studies of teleosts .. . ... ......................... 13 

Acknowledgments .. .... ........ ...... ..... ........................................................ 15 

Literature cited .................................................................... ..... .. ... ...... 16 

Figures 

1. Skeletal structure of Sebastes sp. ..................................... . .................... . . ....... 4 

2. Structure of (A) parts of a teleost vertebral column and (B) precaudal and caudal vertebrae. . . . . . . . . . . . . . . . . . . .. 5 

3. Left lateral view of the caudal complex of a 38 mm SL Argentina silas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7 

4. Left lateral view of the caudal complex of a 68.1 mm SL Scombrolabrax heterolepis from the Atlantic Ocean . . . .. 7 

5. A. Lateral and anterior views of the serial association between pterygiophore and fin ray from an 85.0 mm SL Thunnus atlanticus. B. Lateral view of pterygiophores of the dorsal finlets from an 85.0 mm SL Thunnus atlanticus ... . 10 

6. A. Lateral view of ontogeny of left pectoral girdle from Scombrolabrax heterolepis. B. Ventral view of left and right 

basi pterygia from Scombrolabrax heterolepis ......................................................... 11 

7. Numerically constructed dendogram depicting larval morphological relationships among 12 genera of the subfamily 

Scombrinae .................................... .. ......... ..................................... 14 

Tables 

1. Characters of pelagic life history stages that aid in identification to order or suborder. . . . . . . . . . . . . . . . . . . . . . . . .. 3 

2. Characters of fins that aid in identification of larvae to order or suborder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6 

3. Larval characters presumed phylogenetically important as coded state for comparison of 12 genera of the subfamily 

Scombrinae .............................. ........ ........ .. . ................. . ........ .. . . . .... 14 

4. Comparisons of 12 genera of the subfamily Scombrinae ................................................. 14 

5. Potential characters for analysis of phyletic affinities of teleost larvae ............ .......... .. .. .. .... ...... 15 

III 
FOCU ) 
The Utility of Developmental Osteology in Taxonomic and 

Systematic Studies of Teleost Larvae: A Review 

JEAN R. DUNN I 

ABSTRACT 

Numerous examples from the literature indicate that cartilaginous and bon} ; tructure; aid in the ta \ on· 

omy of teleost larvae. The vertebral column, neural and haemal spines, ribs, predorsal bones, ba;a l ,> upport ... 

and constituent bones of the median and paired fins, and the bones of the skull ha ve all been u;ed to va r y ing 

degrees in larval fish taxonomy. The size, number, and morphology of cartilaginous or bony struct ure; and 

their sequence of ossification have been employed to elucidate identification of larvae. Such tructure .. haH 

been used as characters at every taxonomic level, although no single structure has been found to be useful at a ll 

levels. 

Various methods for preparing and studying cartilaginous or bony structures a re ava ilable (e.g., clea ring 

and staining, and radiography). The use of biological stains for detecting cartilage a nd /o r bone, hOl.eHr, ;., the 

technique most commonly used for larval fishes. 

Studies of developmental osteology have been used only recently to infer phylogenetic relation .. hip,> of 

teleosts. Morphological characters and their development have great systematic utility at all hier arc hica l lev· 

els. Osteological studies of fish larvae and rigorous documentation and analy ses of ; uch studies in the primary 

literature have the potential to notably increase our understanding of teleost phylogen}. 

INTRODUCTION 

Due to similarities in appearance, fish larvae of some groups are 

difficult to identify- using either pigment patterns or morphology. 

Examples of such difficult groups occurring in the ma rine environment include (but are not limited to) clupeids, scorpaenids, gadids, 

scombrids, cottids, and hexagrammids. Because of the problems 

encountered when attempting to identify larvae of these groups, 

detailed studies of developmental osteology are often required . 

Ossified structures may be defined as those skeletal structures 

composed of bone (e.g ., skull and trunk bones); in practice they are 

distinguished in the laboratory by their uptake 01 biological stains. 

usually Alizarin Red . Endochondral bone is preformed in cartil age, 

whereas dermal bones ossify directly from membrane (Wake 

1979). Cartilaginous structures may also be distinguished by their 

uptake of vital stains, usually Alcian or Toluidine Blue, allowing 

one to count or examine the structure of bones which may not ossify 

until late in the larval period , until well into the juvenile stage, or 

never (e.g., epurals, predorsal bones, radials of pte rygiophores, 

etc.). Meristic segments, those structures commonly de fined as 

countabl e structures normally occurring in a series (e .g. , vertebrae, 

neural and haemal spines, fin spines and rays and their supporting 

bones), are often a powerful tool for identifying teleost larvae (e. g., 

Matsumoto et a1. 1972; Richards and Potthoff 1974; Berrien 1978; 

Potthoff 1980; Fritzsche and Johnson 1980). Analysis of osteological tructures can also help place unknown fish larvae in the correct 

order, suborder, and . sometimes, family (Ahlstrom and Moser 

1976). Osteological structures are of demonstrable value in phylogenetic studies and can be of great utility in elucidating systematic 

relationships based on studie of teleost larvae (Moser and Ahlstrom 1970; Ahlstrom et a!. 1976; Kendall 1976, 1979: Potthoffet 

a!. 1980). 

Taxonomy is here taken as the study of groups of organi ms. 

their identification and variation; systematic as the tudv of the 

I orth"e, t and AIa ~a Fi,herie, Cente r. "' auonal ~I nne Fi, he rie, er\lce, 

OAA.2725 lontlake Boule, ard Ea,t . eattle. \\A 9 11 2 

relationships of organisms, their distributIOn. a~~ificatltm. and 

evolution (Bl ackwelde r 1967; see abo Slmp~on 1961 and ~la)r 

1969 for alternate defi nitions). Phylogen} (fnllov.lng la) r 1 t)ot) 

is the study of the lines of evolution of a group of organI~m~ the 

o rigin and evolution of higher taxa. 

Much of the activity of larval fish taxonomlqs lOda) IS stH:alkd 

alpha taxonomy (Mayr et a!. 1953), IdentifYing fj,h lanae to pI.' 

c ies. In the eastern subarctiC PaCific. on I} about 50"'< of the Ian ..Ie 

collected can be Identified to species (Kendall et ..II 19XO) duc 

primarily to such abundant. pccles-nch. and poorl} kno\\ n tanllli es as Scorpae nldae. Cott lda" SlIchaeldae. and AgonIdac 

Inc reased examination of osteological structurcs and their dtlL'Umentation in the forma lltterature may expand our undeNandIng nt 

the relationships ofteleosts as well as enable the pecitic Identltl a 

tion of a larger proportion of larvae. 

The utilit} of developme ntal osteology In taxOntlnllc and S) tcm 

atic tudies of te leost larvae has not pre\lousl) been rL'V IL'W d 

Therefore. in add ition to descnbIng laboratof) mL'thods oInlllonly 

used tll facilitate the stud} of larttiagInous and bony tructure and 

in revieWing perti nent structurcs of the a\lal skeleton, mcdlan and 

paired fins. and cranium. I have attemptcd to ,) nthL'SIIl' thc \allable knowledge regarding the \ alue of the,e ,tructun:s In t xonoml 

and systematic studies of fish Ian ae. In prepanng thl re\ le\\, I 

have drav. n free ly upon previousl) publl,hed papc~ on tdxonOnl\~ 

aids In larval fish studies (Serf) and Richard, I t)7. hi trom and 

Mose r 1976) as well as on unpubli. hed notes trom cia e (;on 

dueted by the late E. H. Ahbtrom~ 
Lr R\ L 

IlDY 

occur through ut 

I) an >;tr:ll:tan" datJ or 

11 n. ofth' ~ rm r pn.. ' cdure The. e pmbJem mdude the deo .. itttlon of bone . du to e ce ,,3cldu) dunng p.:cllllen fi attOn. and 

th po Iblht:- thaI \\ a hmg of pc'imen. follo\\ ing fixation and 

pnor I ) ~<1ntia.!e tainin." ma) render cJrtllage un\lamabJe . tore 

Ii? can.:h L nt:cd<:d. ixlth on cartibge and bone laIn and on melho<L of pre,el"' ing tdeo,t lan;Ie. if \\ e 3re to reI) on Ihe . pecificll:-

of cartilage .md bone. lams. 

Ono (19 '0) Je cnbed a modificatIOn of the WInkelmann and 

chmlt 195"') \11\ er impregnation lCchntque to demon~trJle 

mu de-b0ne-Larttlage relatlon,hip~ in ~mall fishe . Thl ' technique 

i cbimed to be faster than the usual dl)ubl '-~ taining techniques. 

:.md .. ince mu. LIe. tain. their locatIOn and ongIn can be located . 

A number of microscopIc technique mal be used to enhance 

one" abllit) to ob. en e . trucrures in cleared and stained specimens. 

Tmnsfer of speCimens fmm pure gl} enn to solutions of about 60% 

gl)cerin In KOH increases the translucence of the pecimen (Miller 

and Van Landmgham 1969) The use of polanzing filters alo aids 

in dctccting structural details of the specimen ( 1iller and Van 

Landingham 1969). Changmg light intensity and the angle of the 

sub. tage nmror help \ lewmg unstamed cartilage (Potthoff el al. 

1980) The use of a c1m,ed-clrcull telen ion unit attached to a 

mlCr(hCOpe is \ aluable \\ hen detailed examInation of particular 

structures L deSired In cleared and ~tained IMvae. Bones may be 

dissected out of an intact spec imen (We itzman 1974). although disseLl Ion difficult) increase~ \\ Ilh decreasmg size of the specimen. 

UptaJ...e of staIn in Individual fish mal be vanable. DecalcificatIOn of bone occurs \\ ith length of time in Formalin preservative . 

taIn mal r.lpldl, leaLh from OSS ified structure in pecimens 

'" hlch ha\'e been pre\erved ove r a period of time . The examination 

of speumens shortl, after the, have bet:n put through the clearing 

Jnd ... taInIng process IS often necessary (Dunn pers. obs.). We routlnel) Jttempt to maJ...e counts of meristic structures in specimens as 

soon as they are placed In 70% glycenn The specimen-fixation 

problem in relation to uptake of AllLann Red was reviewed by Taylor (1977). He offen;d recommenda!lons on pre ervation techni4Ue\. inclUdIng the use of powdered Itmestone In\tead of sodium 

bllmte as a buffer In Formalin . 

RadiogrJph) IS a rJpld method of examining bony structures. 

The applICabIlity of "soh" X-my ... fo r mdlogmphy of lanai and 

juvenile fishes was reviev. ed by M tiler and ThcJ...er (1979). The use 

nf Agfa GC\aert RPI ( urex or O ... m)) medical film for Juvenile 

dnu adult fishes is relati\eI) inexpensl\e and results In a nega!lve 

supenor to that obtained by the u\e of mammogmph, film Excellent re,ults u\ing \ ariou, other films ha\e heen reported (M tiler and 

'!lIe k.er 1(79), A med ical/dental ftlm proccso.,nr produce, qualtty 

n g.ltl\ ,conSI tentl) and rapidly 

RaJlIlgrJphs oller Ilmltt:J benein\ in \tudying Inwmp1ctely ll\\ilieu II h lanac C.lntlage Joc, not Shll\\ in r.luiogl.1ph\. and radiIlgraph) 11M) c. u,e erronCllU\ conclusion\ a, to the pn:\ence or 

dt> Cllle of stnll(Ures \\ hi h 1ll.1) o\\il) in the late larval or juvenile 

I 'c R, dlogl.lphs may.tI 1 h" h.trd til Interpret, .IS In the dlscnlllindtloll of \en hl,le Inlll prt'l'alld,tI and .lUd.1i groups. In nOl11eld 

II he" th oa k"'drd 1 ndlng .wJ c.:nmdin' lIlgctht'r 01 hacm;!1 

pine tnd nb on Juu<ll \ rtch d I\lade dllli lilt th dtflc.:n.:nlia· 

11>n I pre <lud I and ("lUd I \crtehrac 11'11111 radiO ·ruph .Iithou'h 

nl t on cleared nd tin d [Je(.1/1l n (1\111 trolll ct ,Ii 1971» 

unt uffin pili ftn m\ ,bn.tn hlo tc 'III my nd I 

be nt.lde llh ut re urttn' t; mdlOgraph (II cleil~I;' ifill 

but tnl rJ retutloll u h ounl n rn tim be dlftl 

rnple fd t r a II 0\ orl ) d v. h n e 

n I Ie.: red nd IdIn d I wh (h r r not the I 

ftn r 
in Alizarin stain and 1 % KOH for a few hours to enable more accurate counting of fin rays and branchiostegal rays. 

Electron microscopy (scanning and transmission) may be of 

value in the study of bony parts, but apparently has not been extensively used on larval fishes (~eyer-Rochow 1972). Examples of 

the use of electron microscopy include study of the ultrastructure of 

otoliths in juvenile fishes (Dunkelberger et al. 1980), the development of fins and their structure (Yamamoto and Egami 1974; 

Geraudie 1978), and the development and organization of scales 

(Hughes 1981). 

Other methods are available for defleshing the skeleton of fishes, 

but these are not useful on small and fragile larvae. Examples 

include the use of enzyme "pre-soakers" to produce disarticulated 

(Ossian 1970) and articulated (Konnerth 1965) skeletons or dermestid beetles (Knudsen 1966) for defleshing skeletons. 

SKELETAL STRUCTURES OF TELEOST 

LARVAE AS TAXONOMIC AIDS 

AND SYSTEMATIC CHARACTERS 

Vertebral Column and Associated Bones 

The number, morphology, and sequence of ossification of the 

vertebral column and associated bones of the vertebral centra and 

their appendages, of the neural and haemal spines, and of the ribs 

and intermuscular bones are useful as taxonomic aids and are of 

systematic importance. The manner of formation of vertebral centra, arches, and ribs was described for herring by Manavala 

Ramanujam (1929), for haddock (Gadus aeglefinus = Melanogrammus aeglefinus) by Faruqi (1935), and for Lebistes reticulatus 

by Mookerjee et al. (1940). 

Vertebrae (or myomere~) are one of the h.1 IC l11erJ\lIL h.lrll h: 

used in identification of larval fishes (Tahle I) t-.l) Unlere forl11ll1 

the embryo (Fowler 1970) and are conSidered to he ncar!). If nnt 

exactly, equivalent to the number of \ertehr.le Po Ible eXC ptlon 

to this generality have been suggested h} Hempel and BI,lxtn 

(1961) and by Berry and Richard~ ([973). ~1yomen:s 111.1) he dl fl 

cult to count, particul arly thoe near the skull or near the end III thL 

caudal peduncl e. The use of polanzed light, Immef\ion of the I'LC 

imen in glycerin, or staining the larvae in alcohol-hast:d t,III1' 

(Ru sell 1976) often aid in precise myomere cnunts. Stain, .Jppar 

ently have not been developed whit:h differentiall) hO\\ 111)\l cpt 

and myomeres, although such stains appear potential I) Jca\lhlc 

When counting vertebrae, some authors (c g .. Berr) .Jlld 

Richards 1973) include the ural bones (or uro tyle) as a single unit. 

irrespective of the number of constituent clements. nthcf\ Ic g • 

Cohen and Nielsen 1978) do 110t include ural bones III their counts. 

Partial counts of vertebrae (or myomeres) arc useful v. hen apphLd 

to certain groups of fishes. Preanal, postanal, predorsaJ. and plht 

dorsal myomere counts were used by Houde et al (! 974) III their 

description of the scaled sardine, Harellgula jaquww. Predof\al 

and preanal myomeres were counted in ophichthyid eels b) Faha) 

and Obenchain (1978), whereas preanal and nephric m) omeres 

were utilized by Leiby ( 1979). The possibility of fin or vent nligr.Jtion in relation to the myomeres should not be overlooked v. hen 

usi ng such counts, because these counts may change during ontogeny (Richards et al. 1974). 

In addition to vertebral counts, the gross morphology of thc \ ertebral column or its centra may be of taxonomic importance Ob\ I 

ous examples are the ostariophysin fishes in which the antcnormosl 

four or more vertebrae are modified into the Wcbcrian apparatus 

These vertebrae are commonly included in the precaudal counh 

Table l.--Characters of pelagic life history stages that aid in identification to order or suborder (from Ahlstrom and Moser 1976). 

Character 

I,.arvae 

Predomi nant body 

shape 

Snout to anus length 

Character of gut 

Tra il ing gut 

Number of verte brae 

l.arval stage c haracters 

Larval eyes 

Pleuronectifo rme s 

Various, 

markedly 

Compressed 

Usually 

<4O%SL 

coiled 

Not trailing, 

but gu t can be 

distended 

frolll body 

25 to 65 

Round 

l.arval head spi.nation frequentlyEarly fO l'lD ing fin 

rays or spines 

(often ornate) 

TransfOMU.bon stage 

Early Juvemle stage 

(preJuvenile of 

HUbbs , 1958 ) 

various, 

useful In i dent.. 

Often: 

1 to 12 ant. 

Drays 

Sometillles: 

2 or 3 

V rays 

Marked 

(1 eye shi fts to 

right or left) 

No, 

but larval stage 

can be IUrkedl)" 

prolonged 

Myctophiformes Berycifonnes Perciformes Scorpaeniformes C lupei formes Argentinoidcl StOll' atoidcl AII&Ulll1J o,..e. 

Various, 

often elongate 

40-70%5L 

Straight, 

variously 

shaped 

Slender Varlous, Various. Elongate. 

to stubby usually stubby usually stubby slender 

ca. 30-60%.5L Various I 35-60%5L 65-95%5l. 

20-60%5L 

Coiled Various, 

usually coiled 

Coiled Straight 

Elongate. 

slender 

70-90%51. 

Strught 

Elongate, Leptocephoro1u 

slender 

30-95%5l. 40 9~"-S1. 

(usually long) 

Seldom trailing, Not trailing Not trailing Not trai ling Not tralling Not tralllng Often lra111n&. Seld<;41 tr .. ,1 i 

reverse can 

apply; gut 

gradually 

increases 

in relative 

length on larvae 

/olyctophids 

28 to 4 5, 

others 2 9 to 121 

Round to 

markedly 

narrowed; 

often choroid 

tissue under eye, 

infreq. stalked 

Varlousnone to 

markedly 

heavy 

Occasionally 

P fin rays 

Various. 

often marked. 

sometlmes 

delayed 

sometimes 

prolonged 

Usually 

23 to 33 

ca. Round 

variousnone to 

markedly 

heavy 

Often V 

&. ant. 0 

Usually 

gradual 

In soee foras Sometimes 

(ex. Nacristiella marked (ex. 

stage) Holocentrids) 

ca. 20 to 100+, ca. 2S to 65 

often 24 to 28 

Usually round, 

can be 

narrowed 

wi th choroid 

tissue 

variousnone to 

markedly 

heavy 

ca. Round 

Usuallyuseful In 

ident 

Sometimes No. 

1 or ClOre but P fln C:U\ 

1 st 0 sp. and be qUl te l&r&e 

V sp. &. rays 

Usually 

gradu.l 

SOIIeti.cs 

(In V1I.r 

f_lliesl 

Gradual 

Pelailc 

Juvenile sUge 

(ex. soae 

scorpaenlds 

3 

sometlmes {_rlu~dly 

urkedly traLlu .. g on 

so.e cor'ir.dl 

ca. 40 to 60 ca. 40 to 85 c. 30 to 100. HI to 400 

ca Round 

No 

Marked 

D. It. , \ 

ftns .a .... e. 

ancho\') 

snout (onu 

Round or 

narrowed, 

sometlmes 

st.alked 

Sone 

Round to 

aanr.:edly 

narf'("cd 

~ 

(sulkl."d n 

ccallHI!\a Y 

P n 

Id'thjocOC~'" 

.... u .... e'd 

photophore 

_t 

.. pro led 

• Olt 

)Q to 

Round r 

.aderate y 

\.Ir .... d 

t. '" 

..... 

1 

adl( .,..", 

'.1' ou • eic iah l 

dl!"ep-bod I red 

Ua.u i ",. 

.a 40 .. 

....... 

.. 
(Hubbs et al. 1974; Williams and Bond 1980). The sometimesdiagnostic surface features of centra have been used by archeologists and paleontologists for taxonomic identification (Casteel 

1976). However, like other structures, centra undergo ontogenetic 

changes in shape even after ossification has occurred (Clothier 

1946, 1950; Bond and Uyeno 1981). 

The length of individual centra may vary according to stage of 

development (Kramer 1960); in Scomber japonicus, centra near the 

middle of the vertebral column initially outgrew those more anterior or posterior. In some fishes sexual dimorphism occurs in the 

structure of vertebral elements, such as in the relative size of the 

haemal canal of the first caudal vertebra in Labrus mixtus (Ford 

1937). Other variations in structure, such as the size and shape of 

the first haemal spine and the modifications of neural and haemal 

spines, were included by Clothier (1950) in his key to adult fishes 

and noted by Matsumoto (1963) and Potthoff (1974) for the first 

haemal spine in Thunnus alalunga. 

The separation of vertebral counts into precaudal (abdominal) 

and caudal components (Fig. 1) has useful application in the taxonomy of a number of groups of larvae, even at the species level (Potthoff 1974; Sumida et al. 1979). As commonly defined , the caudal 

centra lack pleural ribs and possess medial haemal spines (Hubbs 

and Lagler 1949; Berry and Richards 1973). In various taxa , the 

haemal spine of the first caudal vertebra is anterior to, or articulates 

with, the first anal pterygiophore (Fig. 1, 2A). In some species of 

nomeid fishes, from one to five caudal vertebrae bear both a haemal 

arch and a pair of pleural ribs (Ahlstrom et al. 1976). These authors 

defined caudal vertebrae in nomeids as those possessing a haemal 

spine regardless of the presence of ribs. They noted that precise 

determination of precaudal and caudal vertebrae could easily be 

made in cleared and stained specimens by following the sequence 

of ossification of samples because the haemal spines ossify earlier 

than the ribs. 

Vertebral counts are of great value in separating larvae which are 

superficially similar but phylogenetically remote, such as clupeids 

and pholids (Russell 1976); vertebral counts also aid in identification of closely related taxa such as species of clupeids (Houde et al. 

1974). The intraspecific variation in vertebral counts must be 

known when using this character to separate closely related taxa 

(Berry and Richards 1973). Unfortunately, few lists of vertebral 

counts and their intraspecific variation are available in the IiteraPredorsal bone Dorsal fin spines 

Supraoccipital 

Epipleural ribs 

ture . Vertebral counts for about 553 species of fishes occurring in 

the eastern Pacific Ocean were listed by Clothier (1950) and Clothier and Baxter (19696

). Hotta (1961) listed vertebral counts for 266 

species in 106 families of fishes in Japanese waters, while Takahashi (1962) listed such counts for 256 species in 100 families. 

Meristic characters (including precaudal and caudal vertebral 

counts) for 642 species of marine fishes of the northwest Atlantic 

Ocean were listed by Miller and Jorgenson (1973), and means (and 

range of means) of vertebral counts of3, 137 fish species belonging 

to 118 families were presented by Lindsey (1975). Lists also exist 

for certain specific groups such as North Pacific blennioids 

(Makushok 1958) and cottids (Howe and Richardson 19787

). 

The shape and structure of projecting processes of the vertebrae, 

termed "apophyses" (Wake 1979), can be of taxonomic significance. Neurapophyses are dorsal projections from the centrum 

which join to form the neural arch; haemapophyses are ventrolateral projections from the centrum which join to form the haemal 

arch (Fig. 2A). Parapophyses are bony projections on each side of 

the precaudal centra to which pleural ribs are attached; zygapophyses are projections of the centra which , in some fishes, may interlock with each other and give rigidity to the vertebral column (Fig. 

2B). These may be separated into neural and haemal pre- and postzygapophyses (Clothier 1950). The size and shape of the apophyses 

were used as a taxonomic character by Clothier (1950) and Clothier 

and Baxter (footnote 6) in their keys to adult California fishes based 

on the vertebral column. Potthoff (1974) described the ontogeny of 

apophyses in tunas (Thunnus) and used the position of the first 

haemal postzygapophyses as one of several characters to separate 

three species of Thunnus. Bond and Uyeno (1981) used the remarkable changes in parapophysis shape which occur during growth in 

Scombrolabrax heterolepis as one character justifying placement of 

this monotypic species in a separate suborder and family. 

The number, size, and shape of neural and haemal spines may be 

useful taxonomic characters in larval fishes as they have been 

6CIOlhier, C. R., and 1. L. Baxter. 1969. Vertebral characters of some Californian 

fishes with notes on other Eastern Pacific species. Unpubl. manuscr., 264 p. Calif. 

Dep. Fish Game , Sacramento. 

7Howe, K. M., and S. L. Ri chardson. 1978. Taxonomic review and meristic variation in marine sculpins (Osteichthyes: Cottidae) of the Northeast Pacific Ocean. 

Unpubl. manusc r., 142 p. School of Oceanography, Oregon State Univ., Corvallis, 

OR 97331. 

Neural spines Dorsal fin rays 

Dorsal fin pterygiophores 

Haem.1 spines 

Anal fin pterygiophores 

~ Abdominal vertebrae ---'---------Caudal vertebrae _______ --' 

Figure I.-Skeletal structure of Sebastes sp. 

4 
A 

p"apo ys s / 

First haemal arch 

B 

Precaudal 

I ntermuscu larbone 

Neural 

zygapophyses 

shown to be for adult fishes by Clothier (1950) and Clothier and 

Baxter (footnote 6) from which the following has been extracted. In 

adults, the most anterior neural spines may differ in shape , length. 

and width from the more posterior spines. The neural and haemal 

spines may be modified into plates (as in Gymnothorax lI1ordax), or 

the first few anterior neural spines may be fused into a bony plate 

(e.g ., Verrunculus polylepis). The terminal three or so neural or 

haemal spines may be truncated distally and laterally broadened, 

whereas those anteriorly situated may be more spinous. In the cottid 

[cel inus quadriseriarus, the last three neural and haemal spines are 

enlarged into wide plates. In bothid and pleuronectid flatfishe , the 

first haemal spine is distinctively strong and heavy, and its structure 

varie interspecifically. Whether or not the centra adjacent to the 

ural centrum (or centra) bears a neural spine is a taxonomic character of value at the ordinal I vel (Ahlstrom and Moser 1976). as 

shown in Table 2 . If reduced or lacking, thi IS often termed the 

"rudimentary neural arch" (Greenwood and Rosen 1971) and. 

when enlarged or variou Iy shaped and aok) losed to other bone. is 

called the "supraneurallamina" b) these authors. 

The first haemal spine and first haemal arch may occur on the 

"-

Haemal spine 

Fi!(ure 2.- \. Structure of par" uf 

a teleo,t Hrltbral column (aft" 

Clothier 1951)); B. "'tructurt of pHcaudal and caudal Hrtthrae faftt r 

Bond 1979). 

same vertebra in some fishes (e.g., £Il~nlllil lIIordlLl. 5\/lod/l 

lucioceps, Merluccius produulIs), aCLOrdlng to CI(lthH!r (I q~OJ 

but more commonl) the first haemal spme occurs po tenor 10 the 

first haemal arch (Fig. 2A). The po. Itlon of the,e 1\\0 (/1 ratl r, 

was used in a ke) to adult fishe, ba,ed on ~eJctal element b) 

Clothier (1950) and Clothier and B,nter (lootnotc 6) Accordmg t 

Clothier (1950). the first haemal ,pine ma) be indeterminate \\ hen 

it is onl) a minute process, \\ ith sub,equent pme b L(>flUng gradu 

all) longer (Sarda, ThuIlI/US, '\('olhuIlIllO). or bee u c the ha mal 

process fuse proximall) onl) J.nd remalm, blfurcatc dl tall) 

(Albula I'lIlpes) In some atherinids (4lhcf1IlOl'f tlhcnI {11/ and 

Leureslhes). the position of the fiN haemal spmc t ob ured b) the 

"haemal funnel" (Clothier (950). In ath nmd thl tru,,(U 

beginS 6 to 10 \crtebrae in lront \.11 the first hemal pm .md I 

e scntiall) a double an.h. the 10\\ amo t part of \ hi h d n t fu 

until the fiN haemal pine form (ther \ anatJon 10 tru ture 

neural and haemal . pme. are do.:um nted b) rord th r 

(1950). and Clothier and Ba ter (footn te 61 

The po. teriormo. t one or mor~ ha rna pin rna) 

nou. or ank) losed to the t:entra FI,mge rna) be p nt 
Table 2.--Characters of fins tho.lt Id In iucnLlflf.:ullQIl of I H'VIt~ l onJr.r- 01 lubfJrtir.r (fro. Ahlalro. ntJ M Ic t 1 1 ). 

ch" ... acte'" 

Typ. 0' fH\ elc .... nt. 

Poctoral "''',Y'' Sequ.nc. of 1"0"'" 

tl0n 

v.ntral (tn. 

S.que"". of (O~ 

POultOn on bud.)' 

fo .... ub 

00 ..... 1 hn{.) 

Ana' ( .. o , A t .... tnal roy 

blrurcattAdlpo,. ". Ca"d.l fi. 'YP' 

Prlnclp.ll C AY' 

jIlAxl.'" no hypuMl1a 

(UM ludt"'a partlypurel) 

111 •• 1_ 1'10 e:pural. 

'0 un.i cent .... 

(ae. te.t 

!-Ieun ... on vertebra 

.dJ "01.1,...1 

Ipu2 of M",nod, ... 

plC'uf"O""o;-tl 

(0,.. •• 

R>loY, 

l.al(' 

$I ... tl.". ".'-1)' 

Thora, tt 

to JUI"I.r 

• . ~!I. " .. 

, fl_ 

t nn, o •• 

'0 

'0 

. "" ho.ot. ....... 

", no b, ,..". <or no 

tolA I ... ",_"a 

. , 

.. ·' ..... 1 

lItjctc'f'hj 10". ... 

".y' 

Varl0,n 

)(Ien ..... 1 

ta,.,y to la t .. 

At>.I,. ~ 

Vanou" 

.. ~ I, . , 

, ". , ( .. o •• 

'Wllly pr ••• nt 

ereel 

" 

. , 

., , . _ .. ., I.' 

fl.,.)' "o"e' 

."Ine. " r-,.. 

Not I.t. 

...... 

r h 11. 110 

'enll '0,.... 

Ipl"'" , "'1' 

'0' .. 

tenor three or four neuml and haeTllal 'pine, (,I '0111<' II hc (c g . 

argentinoids) and have been termed "preural 1I.lng<' .. b} (lI"\~cnwood and Rosen (1971). The~e "nclOge .. \\er Uscu hj thc ~ 

authors as a character to infer ph) logcnctic rel..ltlOn\hlp In cpar.lt 

ing adult argentinoid fi~hes fmm alcp<l~'ephaltd II hc\ 

Recent studies on the ontogen) of neur .. t1 anJ h'H~lI1al pine, 

include Kramer (1960), Potthoff (11)74. 11)75, It)HO) HouJe unu 

Potthoff (1976). Potthoff et al (1980). anu PnlthotT .tnU Kelle) 

(1982). 

The sequence and direction of oS'lllcallon llf Inul\ IJual \ ertchral 

centra and neural and haemal spines afe kmm n to diller umong certain taxa (Moser and Ahbtrom 1970). but uch difkrence\ ha\ e not 

yet been analyzed. Such an analysIs might offer cllnsiuerahk 

insight into phylogenetic affinJtles. 

Ribs (pleural. epipleural. and epineural-Fig. I. 28). as \\e11 us 

intermuscular bones. are seldom-used chamcte~ of potential ta \(lnomic and systematic value. but thelf use is pood, uOlumented in 

the literature. Emellanov (1935) describcd the origin and morphology of ribs in a number of fish species. Intermuscular bones (Fig 

2B) were used as a diagnostic character by Amaoka (1969) in diStinguishing adult bothid and paralichthYld flatfishes. and the pre -

ence or absence of intermuscular bones was uscd b) Hensley 

(1977) in his generic analysis of bothids. The ontogeny of pleural 

and epipJeural ribs in the Pacific mackerel (PnelllnarophoTll'> 

diego = Scomber japonicus) wa decribed by Kramer (1960). In 

the sea bream, Archosargus rhomboidalis. by Houde and Potthoff 

(1976), and in Scombrolabrax hererolepis by Potthoff et al. (1980) 

Fins and Their Supports 

The number, structure, position, and sequence of development of 

the fins are useful in identification of larvae at all taxonomic levels. 

Ahlstrom and Moser (1976) indicated that caudal and pelvic fins 

6 

r' 

~.,.,.... 

"" , M .. .. ,, ·"1' ..,. ... hh ,. .. 

are of rnmc u c tn Id nuri aU n to ordtnal and ubordtna) level , 

"hcre.J th lime 01 ~ rmaU n of pc lor.J) ftn I considered an Ordinal ch.Jra I r Jabl 2) I urth r. thc caudal fin od 11 uppontn 

bones are u ful tn Id OUf) 109 lar.:t I filOlIl}, w hll the median 

tns are m t h Ipful al gen nc and pc lfi le\e1 of Idenu I 

Caudal fin. rh raj 'f th caudal In are thc Irst t 10 If) In 

0]0 t II he • a notabl c ccplIon betng thc tctraodontld in w hi h 

Ihe caUdal lIn ra} arc th~ 13 t to lc\ I p (Be IT) nd RIchard 

1<)7'\) The meOwn raj' ofth uual fin, "hI h n rmall) 3rt1CUbte \\ tth th h) pu al bone, u uall} began If} Ing first, nu 

ue\ elopment u uall~ rroc~cd dorsall~ and \ nlrall~ 

Generall). rmn(,lp.t1 caudal my (Fig .,4) m adult fi h ha\t: 

been defint:d a, thc numN:rofbranLhed raJ plu the adp ent dor-

'<II and \t:ntml unnran('hcu ra) (Hubb anu La..'ler 1949). HowClt:r. thi, ddinnlon doc n tllppl) tn all fi he be(,3U c omc (~.2 • 

Clinid<le. fO<.Hnllte ~) IXI\\C , nn branched rJ) nr the br<lnchmg 

de\clops I,tte (e g . Ju\enilt: anu adult cD((ld • Ho\\e ) and I. often 

of limned use in lanai ta onom). The number of ra), articulating 

\\ Ilh the h) pural bone~. ho\\c\·cr. i phen a u,t:fulta\onllmic character. In ~llme gadid, the number of rJ) e)O the uperior h) pural is a 

generic lharacter (Matarese et al. 19 I). \\ hill' the number of rJ) 

on the second h) pural mal be a ta\onomie charaeter at the ,peLitic 

or generic Icvel (Dunn pel'S ob~.). 

Secondaf) (procurrent) caudal raJ arc generally located ante nor 

of the principal caudal rays. and normall} do not artIculate \\ ith 

h) pural bones. The e \ af) in number among ph) logenetl group 

and usuall) arc the last m) ~ of the caudalwmple\ 10 0 sif). In some 

taxa they may be of taxonomic utility. Among the COUld (footnote 

8). the counts for dorsal and ventral secondaf) raJ are dIstinctive 

HK. M. Howe . COllege of Fi,hene,. Un". \\a,h . Seattle. WA 98195. pe(\ "ommun. December 1980. 
I I PUF 

, .0 rnrn 
for some fishes, e.g., 6- 8 dorsal, 6-8 ventral in Hemilepidotus; 11 

dorsal, 7 ventral in Chitonotus; and 10- 12 dorsal, 9- 10 ventral in 

Scorpaenichthys. The related agonids and cyclopterids appear to 

possess few secondary caudal rays, but the ventral count is often 1 

or 2 less than the dorsal count (footnote 8). In the scorpaenids (and 

hexagranunids) , the dorsal and ventral secondary caudal counts are 

usually equal (foot~ote 8). The distribution and variation of secondary rays have not been investigated in most taxa. 

The homocercal caudal fin is generally considered a conservative 

structure , and the distribution of upper and lower principal caudal 

rays is usually consistent within broad phylogenetic groups 

(Gosline 1960; Berry and Richards 1973 ; Ahlstrom and Moser 

1976). The count of 10 (upper) and 9 (lower) principal caudal rays 

occurs in almost all clupeiform and salmoniform fishes, as well as 

in most berycoids. Perciforms have 9 + 8 principal caudal rays and 

scorpaeniforms vary but have 17 or fewer principal rays, whereas 

pleuronectifo rms have highly variable counts ranging from 10 to 

23 principal caudal rays. Exceptions occur, however. In the cottid 

genus Ascelichthys, the count of principal caudal rays is 6 + 7 

(Matarese\ and a greater number of lower than upper principal 

caudal rays may occur in other cottid genera (footnote 8) as it also 

occurs in ceratiods (footnote 3) and in some catfishes (Lundberg 

and Baskin 1969). The distribution of principal caudal rays on 

hypural bones may vary among genera, as in some cottids (footnote 

8), or among species, as in the Hexagrammidae (Kendall 1<) . 

Detailed examination of the distribution of principal caudal rays in 

various groups of teleosts may result in useful taxonomic characters. 

Departures from the normal homocercal caudal fin ofteleosts are 

taxonomically helpful both in hypural structure and the distribution 

of the associated rays. The isocercal (gadoid) caudal fin is unique 

among teleosts in that the hypural bones support relatively few 

branched rays, some of which may occur dorsad of the hypurals 

(Ahlstrom and Counts 1955). Leptocercal caudal fins in eels are 

markedly reduced , as are those in some blennies. Molids possess a 

unique "pseudocaudal," termed a " clavus " characterized by failure of the notochord to fl ex, a lack of hypural bones, and possession of bones posterior to the last centrum which do not articulate 

directly with fin ray bases (Leis 1977). Much descriptive caudal-fin 

morphology remains to be completed, although the works on adult 

fishes provide a good basis (Hollister 1936; Gosline 1961 ; Monod 

1968; Patterson 1968; Rosen and Patterson 1969; Nybelin 1963 , 

1971; Rosen 1973). 

Hypural bones lie ventrad to the ural centrum or centra (or urostyle if fused) and support principal caudal rays in most teleosts 

(Figs. 3, 4). Counts of hypural bones are made from ventral to dorsal, but are usually expressed as superior plus inferior (e.g., 2 + 2, 

4 + 3, etc.). The anteriormost hypural bone in some fishes is called 

the "parhypural" by some authors (Monod 1968; Rosen and Patterson 1969; Potthoff 1975, 1980) but not others (Moser and Ahlstrom 

1970; Ahlstrom et al. 1976; Richardson et al. 1980; Markle 1980). 

As defined by Nybelin (1963), the parhypural differs from the following hypural bones in that it contains a haemal canal and more 

close ly resembles a typical haemal spine than do the followi ng 

hypural bones (see also Monod 1968). In some phylogenetically 

diverse groups of fishes, the parhypural possesses a lateral flange 

usually terminating in a point posteriorly (Fig. 4)-the parhypurapophy i of Nursall ( 1963). 

"A C l\!ataresc. No rthwest anti Alas ka Fish. Cent. , Na tl. Mar. Fish. Serv., 

NOAA, Seattle, \VA 98112, per;. commu n. December 1980. 

In", \ \ Kentlall, Jr, NOlthwest and Alas ka Fb h. Ce nt., Natl. Mar. Fish. Serv., 

OA \, cattle, WA 98 1 12, per.;. commun . ovember 1980. 

8 

The number of hypural bones is generally consistent among 

related phylogenetic groups, and variation from the norm is a useful 

systematic character. A high number of hypural bones is often taken 

as a primitive character (i.e., seven in Elops and salmonids); reduction is advanced (i.e., four in pleuronectids) as shown in Table 2. 

The hypural bones may be variously fused , ultimately into a single 

plate in adults of some species, e.g., Coryphaena (Potthoff 1980). 

When fusion of hypural bones occurs, it may be observed in ontogeny in some fishes (e.g., Thunnus atlanticus, Potthoff 1975 ; Coryphaena , Potthoff 1980) but not in others (e.g., Ophichthus 

gomesi, Leiby 1979; Microgadus proximus, Matarese et al. 1981). 

This reduction of constituent elements by fusion during ontogeny 

may be useful in analyzi ng relationships at the generic level (Moser 

and Ahlstrom 1970). 

The centra supporting the hypural bones in teleosts are generally 

believed to undergo reduction in numbers by fusion during the 

course of evolution. Again , a high number is usually considered a 

primitive character (e.g. , three in salmonids, occasionally four in 

clupeoids); a single centrum is considered advanced (e.g., Perciformes, pleuronectids) as indicated in Table 2. These are termed 

" ural centra" (Nybelin 1963) or the "urostyle" when they are fu sed 

into one (Gosline 1971). The fusio n of ural centra can often be 

observed in ontogenetic series of cleared and stained ·Iarvae. For 

example, in myctophids, the two ural centra usually fu se into a single centrum before the early juvenile stage, although the two free 

centra may persist in some species well into the juvenile stage 

before fusing (Moser and Ahlstrom 1970). 

Nybelin (1963) and Monod (1968) suggested that the urostyle 

consists of a fusion of a number of ural centra and preural centrum 

one. Hence, in certain groups of fishes some investigators consider 

the ultimate preural centrum as number two and the urostyle to be a 

fusion of preural centrum one and of the ural centra (Rosen and Patterson 1969; Houde and Potthoff 1976; Potthoff 1975 , 1980) as 

shown in Figure 4. Other investigators (Moser and Ahlstrom 1970; 

Ahlstrom and Moser 1976; Sumida et al. 1979; Markle 1980) consider the ultimate preural centrum as number one (Fig. 3). 

Epurals, which support epaxial fi n rays, are small median bones 

dorsal to the ultimate vertebra and posterior to the posteriormost 

complete neural spine or specialized neural arch (Patterson 1968). 

Considered to be neural spines detached from their neural arches 

(Gosline 1960; Nybelin 1963; Patterson 1968), they are of taxonomic and phylogenetic significance in some groups of fishes and 

are generally constant in number within species. There are usually 

one to three epurals, but they may be reduced in number or size during ontogeny (Richardson et al. 1980), fusion can occur (Potthoff 

1980), they may not ossify until well into the juvenile stage as in 

some bathylagids (Dunn 1983), or they may be lacking. 

Uroneurals, paired bones generally occurring dorsolaterally to 

the ultimate vertebra, are often the first bones to ossify in the caudal 

complex. According to Patterson (1968) they are modified ural 

neural arches. They frequently fuse to the terminal centrum, and 

the anterior uroneural may expand during ontogeny. The presence 

of three pairs of uroneurals is considered a primitive character, 

whereas reduction in numbers or even loss (Pleuronectidae) is considered an advanced character. The ontogeny of uroneurals in 

Hiodon , Elops, and Salmo was described by Cavender (1970), in 

Archosargus by Houde and Potthoff (1976), and in Coryphaena by 

Potthoff (1980). 

The presence of urodermals or stegurals is considered a primitive 

character. Urodermals (Nybelin 1963) are medial bones posterior to 

the urostyle (Greenwood and Rosen 1971) and are thought to be 
modified scales (Patterson 1968). Stegurals may be defined as the 

incorporation of the first ural neural arch and usually the first preural neural arch into the first uroneural . The definition of stegural 

differs among authors (Monod 1968; Greenwood and Rosen 1971), 

and questions remain as to the hQmology of "stegurals" among different groups of fishes (Rosen and Patterson 1969). In some fishes 

(e.g., some gadoids, cynoglossids), medial bones occur dorsally 

and/or ventrally anterior to the last neural and haemal spines. These 

are termed "dorsal (or ventral) accessory bones " (Marshall and 

Cohen 1964; Rosen and Patterson 1969) or "X" and "Y" bones 

(Monod 1968), and may be taxonomically significant at the generic 

or subfamily level. 

Other characteristics of the caudal fin may be of taxonomic or 

phylogenetic significance. The procurrent spur of the caudal fin of 

some perciform fishes was described by Johnson (1975) who discussed its phylogenetic implications (Fig. 4). Nursall (1963) 

defined the hypurapophysis as "a lateral process of the anterior 

hypural bone associated with the terminal vertebra (of Gosline 

1960), serving as the anterolateral portion of the proximal attachment of the hypochordal longitudinal muscle." This process was 

noted by Ford (1937) to occur in 24 families; Nursall found this 

process present in 11 additional families. Whether or not the anteriormost hypural (parhypural of some authors) is free proximally is 

considered of phylogenetic significance by some workers (Rosen 

and Patterson 1969). 

The structure of the adult caudal fin in both recent and fossil 

fishes has been widely used to indicate phyletic relationships 

(Greenwood et al. 1966; Patterson 1968; Rosen and Patterson 

1969; Gosline 1971; Greenwood and Rosen 1971 ; Rosen 1973). 

Relatively few authors have analyzed caudal fin ontogeny, and even 

fewer have attempted to interpret the phylogenetic significance of 

the development of this fin. 

Several recent papers on the development of the caudal fin in 

teleost larvae indicate the structure differs from that commonly 

accepted for adult specimens. Contrary to accepted interpretation 

of adult caudal structure, no evidence was observed during ontogeny of a two-part fusion of the ventral hypurd.! plate in Thunnus 

atlanticus (Potthoff 1975). Matarese et al. (1981) noted the absence 

of uroneurals in the caudal fin development of Microgadus proximus, the presence of which was considered by Rosen and Patterson 

(1969) as a characteristic of the Gadiformes. lsopsetta isolepis also 

lacked uroneurals according to Richardson et al. (1980), a structure 

considered by some authors to be characteristic of Pleuronectiformes (Rosen and Patterson 1969; Amaoka 1969). The two pairs 

of uroneurals in Coryphaena fused during ontogeny into a single 

pair (Potthoff 1980). Based on examination of adult caudal fin morphology, the absence (i.e., fusion or loss) of the posterior pair of 

uroneurals could be considered an evolutionary advance (Fraser 

1972). 

The reported absence ofuroneurals in Microgadus and lsopsetta 

does not necessarily imply that fusion or absorption of these structures into the ural centrum (or centra) did not occur during evolutionary history. Similarly, the reported absence of ontogenetic 

fusion (as in the ventral hypural plate of T. atlanticus) does not 

refute the hypothesis that this plate is derived from the fusion of two 

elements. Absence of such structures in adult fishes is still an evolutionary advance, even if it occurs by ontogenetic fusion or deletion. 

Dorsal and anal fins.- The number of dorsal and anal fins, and 

whether the fins are composed of rays only or of spines and ray , 

are useful taxonomic characters and can be indicators of phyletic 

9 

position (Table 2). The number of splOes 10 dor-al or anal flO I 

often constant in many familie or genera, but the number of ra) 

may vary inter- or intraspeclfically. In fishes po, es 109 fin \\ Ith 

both spines and rays, care should be taken 10 di nmlO:llin 

between the two. Separation of the two types based on the adult 

complement does not always apply to larvae. pines and It ra) 

may be fimbriated at the termlflUS 10 larvae , but the e are repl,Ked 

later in spine by blunt or pOlOted tip according to BerT) and 

Richards (1973). Segmentation of soft rays does not nClur until 

after the ray has formed. In certain fishes (e go, Marone I(mlli" ). 

some soft rays may become spines during or after the Ian al ,tage 

(Mansueti 1958). In Sebastes, the po tenormost dor-al 'PIO and 

the third anal spine first form as soft rays and then transform to 

spines, beginning at the base and continulflg distally (Moser et al 

1977; Richardson and Laroche 1979); these were termed "pre 

spines" by Richardson and Laroche (1979) . In many fishes thl: ter 

minal soft ray of the dorsal and anal fins consist of an antenor and 

posterior part but is associated with a single pteryglOphore (Table 2) 

and should be counted as one ray (Berry and Richards 1971) 

Transient ossified structures occurring in dorsal and anal flOS of 

certain groups may aid in identification. Larvae of some epinepheline serranids possess extremely elongate dorsal SplOCS v.hlch 

become reduced during ontogeny (Kendall 1979). Such dlstinctl\.e 

elongate dorsal spines also are characteristic of a number of other 

groups including holocentrids, acanthurids, and balistids DlstlOC 

tive elongate dorsal rays occur in bothids, lophlids, and bregma 

cerotids, and elongate anal rays are present in some lophiids. 

When using the structure, shape, and positIOn of dorsal and anal 

fins as taxonomic characters, one should keep in mind that in some 

fishes (e.g., c1upeids) these fins may migrate antcriorly or poste 

riorIy during ontogeny (Houde et al. 1974). Additlonally, dor-al 

and anal fins may form in the fin fold and attach to the body b) 

"streamers," as in argentinoids (Ahlstrom 1969; Moser [1981 n. 

In some phylogenetically distant groups of fishes, the dor-al and 

anal fins may form early (e.g., Engraulus, some stromatllds. 

Syacium), whereas in other groups these fins may not OSSify until 

transformation to the juvenile tage (e.g., Leuroglossus IChtlllJri, 

Dunn 1983). Dorsal fins may form before or after the anal fin or 

they may form simultaneously. In species v.ith more than one dorsal or anal fin, the sequence of ossification of the vanous fins rna) 

differ among taxa . The second dorsal fin forms (simultaneousl) 

with the anal) before the first dorsal fin in Scomber japOI1ICIlI. Frochurus symmetricus, Scombrolabrax heterolepl!>, and Anholllr 'III 

rhomboidalis (Kramer 1960; Ahlstrom and Ball 1954; Houde and 

Potthoff 1976; Potthoff et aI. 1980). In Merlucciu~ proJUUII the 

first dorsal fin forms before the second dorsal fin and the anal 110 

(Ahlstrom and Counts 1955), as It does in most gempyhds and .tIl 

scombrids, except Scomber and Rastrel/iger (Potthoff I; . fat umoto 1959, 1962, 1967; Voss 1954). In MlcrogatilH pro Willi • thl: 

first anal fin is the first to form (after larval pectoml fin ) lollov.l:d 

by the second anal fin. Nearly ~imultaneously, the thmJ. e( nd. 

and first dorsal fins develop (Matarese et al 1981). In :J related 

gadid, Theragra chalcograrmna, anal fin one and t\HI and du al 

fin three form together, followed b, the ewnd and then th first 

dorsal fin (Dunn. pers. ob ) The sequence of 0 IticatJon of plO 

and/or rays of the dorsal and anal fin vane among dlff rt'llt 

groups of fishe . Ossification rna) begin 10 the center of th flO and 

progress anteriorad andlor po. tenorad (e.g., Seha It rant n 

Richard on and Laroche 1979: COf}phaena, Potlh ff 19 0) r II 

liT. Ponhoff. Southeast F"h Cent 'ham I Labornt ry atl \u F h rv 

OAA. Miami, FL 331-19, pen; mmun Januaf) 19 :! 
Figure 5.-A. Lateral and anterior 

views of the serial association 

between pterygiophore and lin ray 

from an 85.0 mm SL ThullIlUs 

at/anticus. 1) Fifth spiny ray of the 

lirst dorsal lin and its serial pterygiophore, lateral view on left and 

anterior view on right; 2) Eleventh 

ray of the second dorsal lin and its 

serial pterygiophore, lateral view 

on left and anterior view on right; 

3) Third finlet and parts of its 

serial pterygiophore, lateral view 

on left and anterior view on right. 

S ; spiny ray; 0 ; distal radial; 

p ; proximal radial; R ; ray; 

M ; middle radial (from Potthoff 

1975). B. Lateral view of pterygiophores of the dorsallinlets from 

an 85.0 mm SL Thullnus at/anticus. 

Left to right: PRI4 ; Proximal 

radial serial with the 14th ray of the 

second dorsal fin; NS22 ; neural 

spine of the 22nd centr um ; 

PFl ; proximal radial serial with 

the lirst lin let; ORIS ; distal radial 

serial with the last (15th) ray of the 

second dorsal lin, partly hidden by 

the base of the ray; R15 ; last ray 

(15th) of the second dorsal fin; 

MFl ; middle radial serial with the 

first finlet; Fl ; first finlet; 

XF8 ; fourth radial or stay of the 

last (8th) finlet (from Potthoff 

1975). 

A 

B 

1-----4 

IOmm 

1 

NS22 

may be initiated at the anterior (Merluccius productus, Ahlstrom 

and Counts 1955; Citharichthys, Ahlstrom and Moser 1975) or 

posterior (ldiacanthusfasciola, Beebe 1934) portions of the fins. In 

those species possessing spines in the dorsal and anal fins, development may begin at or near the origin of the fins (Berry and Richards 

1973) as it does for gempylids and scombrids (footnote 11). 

The ontogeny of dorsal and anal finlets in the carangid, Elagatus 

bipinnulata, was discussed by Berry (1969), in scombrids, Thunnus atlanticus, by Potthoff (1974), and in Scomber japonicus by 

Kramer (1960). 

The supporting structures of the dorsal and anal fins, called 

"pterygiophores" (Eaton 1945) or, by some authors, " interneurals" (e.g., Kramer 1960), are generally composed of three parts: 

Proximal, middle, and distal radials (also called pterygiophores; 

Wake 1979; Fink and Weitzman 1982) as shown in Figure 5. The 

presence of three components is considered a primitive character 

(e.g., salmonids, Norden 1961; bathylagids, Borodulina 1969); the 

middle and proximal radials, however, may be fused into a single 

structure (e.g., Scomber japonicus, Kramer 1960; Coryphaena, 

Potthoff 1980)-considered an advanced character. In some cases 

the three components may be fused into a single structure (e.g. , 

fl14 

10 

15 

._ .. _._ .. _p --_ ... _--

2 

>-----< a .SCmm 

MF2 

1 

PF3 : 

NS26 

- --- M --

r-1 

3 

I--------t 

O.SOmm 

F4 F5 F6 F7 

MF5 MF6 MF7 

FB 

XFB 

TUapia macrocephala, Eaton 1945 ; Blenniidae and Labridae, 

Lindsey 1955); a fourth radial , called a "stay, " may be present 

(Fig. 5), as in the last finlet of Thunnus (Potthoff 1975). The number of pterygiophores is usually smaller than the number of fin rays 

or spines, in that the anteriormost or posteriormost pterygiophore 

may support one or more fin elements (Fig. 1). In S. japonicus, the 

pterygiophores are continuous between the first and second dorsal 

fins, but some do not support fin spines (Kramer 1960); such interneurals are also found between fins in some gadids (Dunn pers. 

obs.). Some pterygiophores (usually the first or last) may be bifurcate or variously expanded (e.g., tetraodontids, Tyler 1980); and 

fusion of adjacent pterygiophores may also occur (e.g. , T atlanticus, Potthoff 1975). The anteriormost dorsal and anal pterygiophores represent a fusion of two in many Perciformes (Potthoff 

1975; Fritzsche and Johnson 1980). 

The number of pterygiophores in the first interneural space differed between two species of Coryphaena , according to Potthoff 

(1980). Pterygiophore ontogeny has been described for S. japonicus (Kramer 1960), Thunnus atlanticus (Potthoff 1975), Archosargus rhomboidalis (Houde and Potthoff] 976), Morone spp. 

(Fritzsche and Johnson 1980), Scombrolabrax heterolepis (Pot-
A 0~CI 

1 I------l 2 

2.0mm 0.5mm 

B 

CP 

IDW 

EVW 

EDW 

VW 

AX 

PX 

1 ~ 2 ~ 

1.0mm o 10mm 

thoffet al. 1980), and CoryphaellCl (Potthoff 1980). The ontogeny 

of dorsa l and anal finlet~ 10 the carangid Elagufls blplIIllulalCl \\ a~ 

di cu sed by Berry (1969); in the scombnd , 77ll11l1l1/S ulllIllIiclO, 

by Potthoff (197.f); and in Scolllherjapoll/cus b) Kramer (1960). rn 

addition to its u e a a taxonomic character, pter} glOphore morphology may be an important tool 10 ph) loge netic studies (Potthoff 

1975; Potthoffet a1. 1980) 

Pectoral fin and their upport .-Generall) pectora! fin form 

later in the larval stage than median fins (Table 2) and. therefore. 

are somewhat less \ aluable a a taxonomic aid 10 the Identlficatlon 

of larval fihe . Inome myctophld larvae. pectoral fins ma) be 

large. con plCUOU appendage \\hlch become reduced in .Ize durmgontogen) (Moser and hlstrom 1970. loser [19 l)l Pectoral 

buds are the first fins to form 10 mo t IJn ac. but dey elopment of 

rJ) usuall) lag behmd those of other fms (Table. I 2). Ho\\c\ er. 

10 the m )hd RlIlI::'lIl1ill the pectoral fin. are thc t rst to dc\ clop raJ 

(LCI, 1977). Earl) dey eloping pcctoral fin. are al. 0 found in m~ 

dlll.\(t'.1 It\.10 er et al 19 7) and 10 loph Id. 1(lotnLtc 3) In me 

anguilhform .. Ian al pt.'Ctor.l1 tins are b\.:kmg, \\ herea 10 7i.1 to 

\(Olllll. idiacOII(hlls, and om malaeo teld the Ian I PC't ral re 

3 I 

0.25 mm 

~ 1\ 

Ct 

P 

3 ~ 

o 10mm 

II 
Coryphaena; Potthoff et al. 1980 for Scombrolabrax; and Potthoff 

and Kelley 1982 for Xiphias gladius). 

The reduction or total atrophy during ontogeny of the cartilaginous posterior process of the coracoid apparently occurs in most 

fishes (Swinnerton 1906; Starks 1930; Potthoff 1980), but such a 

process is lacking)n developing Theragra chalcogramma (Dunn, 

pers. obs.). The number of supporting elements of the pectoral fin 

(radials) may be a generic character in some fishes. As an example, 

they range from two to five in various genera of lophiiform fishes 

(Pietsch 1981). 

Pelvic fins and their supports.- Counts of pelvic fin spines 

and/or rays are taxonomically useful in many fishes (Table 2). In 

most perciform families, pelvic fin counts are stabilized at one 

spine and five rays (I, 5) according to Regan (1913). In pleuronectids and bothids the pelvic fin counts are stabilized at 6 rays (in each 

fin) , whereas in soleids the count is 5- 5 and in cynoglossids the 

count is 0-4 (footnote 3). In myctophids the pelvic fin ray count is 

usually 8, but in some genera the count is reduced to 7 (Gonichthys) 

or 6 (Notolychnus) (Moser and Ahlstrom 1970). Pelvic fins are 

absent in a number of fishes (e.g., trichiurids, stromateids, stichaeids, Ammodytes, and some lophiids); others have only a single 

spine and no rays as seen in some balistids (Nelson 1976). In some 

fishes (e.g., clupeoids) the pelvic fins may undergo migration during ontogeny (Russell 1976). 

Elongate pelvic rays are found in gadids, macrourids, and trachipterids, and in some serranids and ceratioids; whereas elongate pelvic spines are present in some serranids, lutjanids, trichiurids, and 

others (footnote 3). Pelvic fins often ossify in an inward direction 

(Scombrolabrax, Potthoff et al . 1980); in some fishes the ossification of all pelvic fin rays occurs nearly simultaneously. 

The pelvic bone or basipterygium (Fig. 6B) has also been used as 

a systematic character in adult fishes (Collette and Chao 1975; 

Tyler 1962, 1980), but has rarely been investigated in larval fishes. 

Sewertzoff (1934) discussed the pelvic bone among various groups 

offishes, while Gosline (1961) discussed the structure of the pelvic 

bone in adult " lower" fishes. 

In many teleosts, radials are present between the pelvic rays and 

the pelvic girdle (Gosline 1961), but they may be lost in various 

diverse groups (Gosline 1961 ; Potthoff 1980). Additionally the pelvic bones may be fused (e.g., some tunas, Collette and Chao 1975), 

they may be highly modified (some balistoids, Tyler 1962, 1980), 

or lost (e.g., Mola, Tyler 1980). 

The ontogeny and structure of pelvic bones were described by 

Potthoff (1980) for Coryphaena and Potthoff et al. (1980) for 

Scombrolabrax, while Fritzsche and Johnson (1980) briefly 

described the ontogeny of the basipterygia in Morone. 

Other Skeletal Structures 

Teleosts possess a great number of other skeletal structures, particularly of the head and axial skeleton, which may be of taxonomic 

and systematic use when applied to fish larvae. 

Branchiostegal rays.-Branchiostegal rays often form their 

adult complement relatively early in the larval period, and their 

position and number are of value in separating some groups of 

fishes, particularly in taxa considered advanced (McAllister 1968). 

Numbers ofbranchiostegal rays may vary in some groups, whereas 

in other groups they may be relatively constant. For example, number of branchiostegal rays varies from 7 to 19 in engraulids, 5 to 24 

in stomiatoids, and 17 to 51 in ophichthid eels. They are relatively 

12 

constant in other groups, including argentinoids (Nansenia 3 to 4, 

Bathylagidae 2), percoids (usually 6 to 7; Bond 1979), Lampridiformes (5 to 7), Pleuronectiformes (6 to 8), Batrachoidiformes (6), 

etc. (McAll ister 1968). In giganturids and Saccopharyngiformes, 

branchiostegal rays are wanting in adults (McAllister 1968; see 

also Orton 1963). 

Gill rakers and pharyngobranchial apparatus.-Because gill 

rakers usually form relatively late in the larval period and the adult 

complements are often not reached until well into the juvenile 

stage, this characteristic is sometimes of little taxonomic value. 

The presence of rudimentary gill rakers in some fishes and the difficulty of distinguishing them from adjacent normal gill rakers have 

led to inconsistency in the literature (Moser and Ahlstrom 1970). 

Additionally, gill rakers are lacking in some fishes (Giganturoidea) 

and extremely reduced in others (e.g., Psettodes). In some groups, 

however, counts of gill rakers on the epibranchials or ceratobranchials or the length of particular gill rakers may be of value in discriminating among allied species (Potthoff 1974; Richardson and 

Laroche 1979). Gill arch structure among adult fishes has been the 

subject of extensive reviews by Nelson (1967, 1969, 1970), Greenwood and Rosen (1971), and other workers ir. a search for phylogenetic affinities. 

Pharyngobranchial teeth are often one of the first elements to 

ossify in teleost larvae (Moser 1972). The sequence of calcification 

of branchial elements was described for myctophids by Moser and 

Ahlstrom (1970) and for Sebastes macdonaldi by Moser (1972). 

Potthoff et al. (1980) described the ontogeny of gill arches in Scombrolabrax. 

Oromandibular teeth.- Teeth on the maxillary, premaxillary, 

vomer, palatine, dentary, and glossohyal bones are often used as 

taxonomic characters in adult fishes. In general, the adult and juvenile complement of teeth differs markedly from those in larval 

fishes in number, size, and shape (e.g., Ahlstrom and Counts 

1958), although in some species teeth added during metamorphosis 

may be retained in the adults (Moser and Ahlstrom 1970). 

Tooth ontogeny in teleosts is poorly known and is a subject ripe 

for further study. Teeth in many larvae initially emerge in a single 

series, but as more teeth are added they tend to emerge between 

existent teeth and often form multiple rows. Teeth apparently are 

added slowly during transformation in some species (Scomber 

japonicus, Kramer 1960) and more rapidly in others (lsopsetta isolepis, Richardson et al. 1980). Leptocephalus larvae of some fishes 

(e.g., Elopiformes, Anguilliformes, and Notacanthiformes ) possess fang-like teeth in the upper and lower jaws; they are apparently 

not homologous with teeth in adult eels and are shed or resorbed 

during metamorphosis (Smith 1979). In larvae of Scopelosaurus, 

teeth on the maxillary are apparently shed or resorbed, as they are 

not present in adults (Berry 1964). In the bathylagid Leuroglossus 

schmidti teeth on the glossohyal disappear during transformation; 

hence the common name "smoothtongue" (Dunn 1983). 

It is generally believed (Scott and Symons 1964; Jollie 1973; 

Fink 1981) that teeth of teleosts are continuously replaced, but 

questions apparently remain as to such replacement (Hildebrand 

1974). The tooth-replacement mechanism may also differ among 

kinds of fishes (Lawson and ManJy 1973; Holmbakken and Fosse 

1973; see also Edmund 1960). 

Fink (1981) described four major tooth-attachment modes in 

actinopterygian fishes and concluded that paedomorphic tooth 

development can be associated with major phylogenetic groups' of 

teleost fishes. Suga et al. (1981) analyzed the fluoride concentra-
tion in teeth of tetradontiform fishes and compared the levels 

observed with the phylogenetic tree proposed for the order by Tyler 

(1980). The authors concluded that the fluoride concentration in 

the enameloid is closely related to the propo ed phylogeny. 

Predorsal bones.- Predorsal bones are usually slender splinter 

bones which precede the pterygiophores supporting the spines or 

rays of the first dorsal fin (Fig. I). Thought to be derived from 

pterygiophores (Smith and Bailey 1961), they insert in interneural 

spaces, and their number and arrangement are in some groups of 

fishes a taxonomic aid as well as a character relating to phylogeny. 

Smith and Bailey (1961) investigated the relationships of predorsal 

bones, dorsal fin spines, and dorsal fin pterygiophores in adult 

fishes in the families of the superfamily Percoidea and illustrated 

some hypothetical evolutionary trends in dorsal fin supports. Predorsal bones and spine-bearing pterygiophores in adult serranoid 

fishes were examined by Kendall (1976) who found phylogenetic 

relationships. Counts of predorsal bones and their relationship to 

spine- or ray-bearing pte rygiophores were used by Ahlstrom et al. 

(1976) as a diagnostic aid in separating stromateoid larvae. The 

position and shape of predorsal bones differed between larvae of 

Morone saxarilis and M. americana (Fritzsche and Johnson 1980). 

Predorsal bones may often ossify either in late larvae or well into 

the juvenile stage but may form early in cartilage. Use of a 

cartilage-bone tain will enable detection of predorsal bones when 

formed, as shown by Fritzsche and Johnson (1980). Discriminating 

predorsal bones by radiography is sometimes difficult, but Kendall 

(1976) successfully used radiographs in his study of adult serranids. 

Head spines and sculpturing.-Spines located on the head of 

teleost larvae may be an important diagnostic character (Table 1). 

Ridges, crests, or variou sculpturing of head bones may occur in 

some larvae and be useful in specific, generic, or familial identification. Some head spines are transient , whereas others (particularly 

opercular spines) may persist into the juvenile or adult stage . These 

spines, crests, or ridges may vary intra pecificall~' in size, shape, or 

sculpturing. 

Spines, crests, or ridges are often associated with the opercle 

bones, supraoccipital, pterotic, or other head bones; they may be 

located on the nuchal, snout, or supraoccular regions and are found 

in a number of diverse groups of fishes such as melamphids, scorpaenids, erranids, istiophorids, carangids, and pleuronectids. 

A number of authors have used head spination as a diagnostic 

character. Examples for scorpaenid larvae are Mo er et al. (1977), 

Richardson and Laroche (1979), and Laroche and Richardson 

(1980); for serranid larvae Kendall (1979); for carangid larvae 

Aboussouan (1975); and for cottid larvae Richardson and Washington (1980). 

Scales and lateral line pores.- Scales rarely develop until the 

juvenile stage and hence are of small value in identification of larvae. A number of exceptions occur including some serranids (Kendall 1979), chiasmodontids (footnote II) , Xiphias gladius 

(Potthoff and Kelley 1982), holocentrids, and branchiostegids 

(Okiyama 1964) in which scales form during the larval period . The 

count of lateral line pores or of diagonal scale rows in juveniles, 

however, may be an important tool in identification of juveniles and 

adults which can be traced back to the larvae (e.g., Laroche and 

Richardson 1980). 

Cranial bones.- Osteology of the teleost skull has long been 

13 

used in taxonomic and phylogenetic studIes of adult ft~hes A, 

demonstrated most recently by Fritzsche and Johnson (1980), the 

ontogeny of cranial bones can proVIde dIagnostic dIfference, at the 

species level. 

The structure and shape of cramal bones (particularly the supraoccipital, epiotic, prootic, alisphenoid. and parasphenoid) v.ere 

used by Clothier (1950) as a taxonomic character In his key to 

southern California adult fi he . The lack of an orbitosphenoid and 

the presence of antorbitals in adult Leuroglossus schmic/ri were 

noted by Borodulina (1969), who used these trenchant characters 

for removing Leuroglossus from the synonomy of Burhylagus. Paxton (1972) separated myctophids into two subfamilies based on 

photophore arrangement and adult osteology (includIng jaw length 

and unsculptured circumorbitals with an extensive orbital shelf). 

These two ubfamilies corre ponded closely to the classIfication 

independently proposed by Moser and Ahlstrom (1970) based on 

larval morphology, particularly eye hape . Recently Fritzsche and 

Johnson (1980) compared the early 0 sification of two species of 

Morone and noted osteological differences between them. Including the shape of the ethmoid cartilage. 

A number of workers have described the ontogeny of cramal 

bones in teleosts; some examples include Weisel (1967) for Catosrom us and Poecilia, Moser and Ahlstrom (1970) for myctophlds, 

Aprieto (1974) for carangids, and Mook (1977) for Archosurgus. 

Study of the development of cranial bones In teleost larvae 

appears to offer a valuable avenue of pursuit, and Its increased use 

could assist in differentiating closely related taxa. 

EXAMPLES OF THE USE OF 

DEVELOPMENTAL OSTEOLOGY IN 

SYSTEMATIC STUDIES OF TELEOSTS 

Ahlstrom and Moser (1976) pointed out that a combinatIOn of 

morphological and meristic characters i not only of value in IdentIfying larval fishes to order, suborder, and often to family, but that 

such characters can be used to infer phylogenetic affinities. As 

shown in Tables I and 2, morphological and meristtc characters can 

be used to assign unknown larvae to order or suborder. The characteristics of fin position, development, and structure are particularly 

useful in taxonomy and systematics. 

Although ' number of authors have used characteristics of larval 

fishes as a means of analyzing phylogenetic affinities above the 

species level (e.g., for ceratioids, Bertleson 1951; for myctophlds, 

Moser and Ahlstrom 1970, 1972, 1974; for serramds, Kendall 

1979; for coryphaenids, Potthoff 1980; and for Scombrolabracidae, Potthoff et al. 1980), few workers have attempted to analyze 

phylogenetic affinities in a rigorou , quantitative manner. Even 

fewer have used developmental osteology in such analyses. A fev. 

examples of such attempts follow. 

Employing an approach previously ued on adult fishes by Ebeling and Weed (1973), Okiyama and Ueyanagl (1978) analyzed 12 

of the 14 genera of the subfamily Scombnnae (Scombridae) according to a sequence of primitive to advanced character state . A 

"character" may be defined as any attribute of an organism, and a 

"character state" a the qualitative and quantItative description of 

the character in question (Sneath and Sokal 1973). Oki) ama and 

Ueyanagi (1978) a signed coded values to 13 characters (Table 3) 

including head spination, ize and shape of premaxillary teeth, 

pre ence or absence of a cartilaginou pad on lower jav., and myOmere counts. By summing the character- tate code \alue (Table 4), 

they arrived at an index of primitivene s v.hich allowed them to 

con truct a dendrogram depictIng morphological relationship 
Table 3.-Larval characters (c hiefl) adnnced postlanal or earl) jmenile 

stages) presumed ph) logeneticall) important as coded stat es for comparison of 

12 genera of the subfamily Scombrinae (fr om Oki)ama and Ue)anagi 1978). 

Char. 

index 

2 

3 

4 

5 

6 

7 

8 

9 

10 

II 

12 

13 

Character 

Supraoccipital 

spine 

Head 

Viscera 

and vent 

Snout 

Premaxillary 

teeth 

Jaw 

Preopercular 

spine 

Spiny supraorbital crest 

Pterottc spine 

Cartilaginous 

pad on lower 

Jaw 

Dorsal body 

pigmentatton 

Post yent 

p'gmentatton 

Myotome counts 

absent 

small; 

< '13 ofSL 

compact; wide 

space from 

anal fin 

rounded 

minute 

equal size 

absent 

absent 

absent 

absent 

heavier 

present, 

extensive 

low; 30-31 

Coded state 

pointed 

large 

equal or 

unequal size 

present or 

absent 

present or 

absent 

absent or a 

few dots 

middle; 38-4 1 

3 

present 

large; 

> 11:3 of SL 

elongated; vent 

just in front 

of anal fin 

elongated 

large; some 

fang-like 

unequal; distinct 

upper jaw 

projection 

present 

present 

present 

present 

lighter 

absent 

Ihigh; 40-65 

I Exceptional 10" vertebral count of Scomberomorus sinensis is responsible for 

this undearly discreted coded state. 

among the 12 genera studied (Fig. 7). Groups "A," "B," "C," an

" D " of Figure 7 correspond well to generic affinities previousl

postulated by Richards (1973) on the bases of myomere counts an

pigment patterns, as well as to affinities postulated by Collette an

Chao (1975) based on characters of adult fishes. 

Using larval as well as adult characters, Johnson (1974) analyze

generic relationships of Scopelarchidae. He analyzed primitive an

advanced states of six larval characters in addition to 15 adult cha

acters, including several osteological characters: 1) extent of per

toneal pigment; 2) presence or absence of accessory pigment spots

3) gradual or abrupt metamorphosis; 4) position of pelvic fin bud 

in relation to the dorsal fin; 5) precocious or nonprecocious appea

ance of the pectoral fin; and 6) head length relative to standar

length . He also determined the length of the basihyal, and whethe 

Table 4.-Comparisons of 12 genera of the subfamily Scombrinae. For the 

characters and their coded state, see Table 3 (from Okiyama and Ueyana

1978). 

Coded character states by character number Tot

Genus 2 3 4 5 6 7 8 9 10 I I 12 13 sco

Scomber 

Rastrelliger I 

Gralllmatorcynus I 3 

Scolllberolllorus 3 3 

Acalllhocybiulll 

Sarda 3 

GYlIlnosarda 

Allothunnus 

Aluis 3 

Euthynnus 3 

KatsuH'onus 

Thunnlls 

3 

3 

2 I 

1 32 

332 

3 2 

3 3 

2 2 

2 2 

2 2 

2 2 

2 2 

I 

I 3 

2 3 

3 3 

2 3 

3 3 

3 

3 

3 

3 

3 

I 

2 2 

I 3 

3 3 

3 3 

3 

3 

I 

2 

3 

I 

3 

I 

3 

3 

3 

3 

3 

3 

3 

3 

I 

3 

3 

I 

2 

I 

3 

3 

3 

2 

2 

2 

2 

2 

2 

13 

13 

18 

28 

32 

29 

34 

24 

24 

24 

24 

25 

Figure 7.-Numerically constructed dendogram depicting lar-

,al morphological relationships 

among 12 genera of the subfamily 

Scombrinae (from Okiyama and 

Ueyanagi 1978). Groups A-D represent related genera, based on 

data in Table 3 as coded in Table 4. 

Group A is considered the most 

primitive group; Group D the most 

derived. 

Class intervals of numbers of coincident character states 

between pairs of genera 

2 4 5 9 10 13 

13 Scomber,' Rastrelliger Group ii

15 

Grammatorcynus 

Group B 

'" '" Q) 

c 20 Q) 

> 

~ 

.§ 

a. 

'+-

0 

x 25 Q) 

"0 

C 

Allothunnus; Auxis,' 

Euthynnus,' Katsuwon 

- Thunnus 

us ( 

~ Group 

Scomberomorus 

30 Sarda 

Group 

Acanthocybium 

35 Gymnosarda 

14 
or not teeth were present. John on used these characters and character states to infer relation hips among species and to group scopelarchid species into genera. 

Certain larval characters were used by Zahuranec (1980) in his 

cladistic analysis of myctophlds of the genus Nallllobrachium. In 

addition to using a number of adult characters, he analyzed ontogenetic characters to establ ish criteria of polarity of characters (i .e., 

from primitive to derived). Larval characters used by Zahuranec 

were: 1) Pectoral fin size and shape; 2) direction of orientation of 

pectoral fins; 3) pectoral ray thickness; 4) pectoral ray fuion to the 

edge of the cleithrum during ontogeny; 5) larval snout shape; 

6) presence or absence of a swim bladder in larvae; and 7) presence 

of a fat-filled or gas-filled swim bladder. The adult and larval characters were used to construct a Wagner tree (Kluge and Farri 1969; 

Farris 1970) to hypothesize phylogenetic relationships of pecies in 

Nanllobrachium. 

Washington (1981) used 11 larval characters in a Wagner tree 

analysis (Farris 1970; Farris et al. 1970) of larvae of three cottid 

genera, Artedius. Clinocottus, and Oligoco((us. She used the following characters: I) Number of preopercular pines; 2) size of 

preopercular spines; 3) presence or absence of basal spines on preopercular spines; 4) number of auxiliary spines on inner helf of 

preopercle; 5) presence or absence of bubble of skin at nape; 

6) presence, absence, and size of gut diverticula; 7) number and 

modification of parietal spi nes; 8) presence or absence of melanophores on nape; 9) snout pointed or round; 10) presence or absence 

of trailing gut and, if present, the configuration and length of the 

trailing gut; and II) number of pelvic fin ray. 

Based on these characters, Wa hington (1981) erected a cladogram inferring systematic relationships of the three genera and 13 

species. She concluded that two sister groups exist within the genera examined: I) Those with multiple preopercular spines, and 

2) those sharing two derived characters-basal preopt;rcular pines 

and pointed snouts. 

The investigation of phylogenetic relationships following the cladi tic approach of Hennig (1966) has stimulated an inten e debate 

in systematics ( ee, for example, the last 10 or more years of the 

journal Systematic Zoology). This conceptual approach has been 

little u ed with larval fishes, yet larval fishes possess a rich suite of 

characters and character states. In many groups of fishes, the larval 

stages exist in habitats di tinctly different from adults (e.g., planktonic larval pleuronectids vs. demersal adult pleuronectids). 

Hennig ( 1966) propo ed that ontogeny should be u ed as a criterion for analyzing phylogenetic relationships and establIshmg the 

polarity (direction) of character states from primitive to derived. 

Eldredge and Cracraft (1980), in their pre entation of cladistic 

methods, restated Hennig's idea concerning ontogen} and stated 

that it is urprising that little attention has been directed toward 

using ontogenetic data in systematics. 

Listed in Table 5 are a number of characters of potential value in 

analyzing phylogenetic affinities among teleo~t larvae. A number 

of other characters might also lend themselves to stud) and anal}-

is, the most notable of which are bones of the neurocranIum (see 

Fra er 191'2 for examples of character state of adult apogonIds) A 

combination of o teo logical and other charaLter states \\ould be 

ueful in any such analysis. 

Analyse of character states ' uch as \\ ere done b) 01,,1) ama and 

Ueyanagi t 197 ) can be of \ alue in eumatmg ph) logenetH: affinIties at genenc Jnu higher level. depending upon the particular 

SUIlC of characters chosen and how thc) are Jnal) zed ~1ore rigorou quantltatl\e approache. to ph) logcnetll anal) ,I. (klugc and 

Farris 1969: mlth and Koehn 1971. Ma", and Rabb 1972: Baird 

Table 5.-Pntenlial,harallcr, fur anal • olllll\llli 

'Ole; character u,uall) "I' ,alue (+, and OI11('llIn< uf, 

hierarch.callc-el. 

Morpholog.cal 

P'gmcnl pallern 

Predominant b"dy hare 

Snoul·anu, lenglh 

Charactcri"t1c\ 01 gut 

Pel"c fin p'hll.on 

Lanai e)e shape 

Tr..ln,formatlon'tage: 

PreJu'cnlle ,Iage prc,cnt 

O'leologlCal 

~umnL'r of \ertchrac 

Number of bmnlhll"tcgal, 

Do"a".n(s': Number 

T) pc of elemenl, 

Formula 

Sequence of format um 

Anal fln(,' !\umber 

T) pe of clement, 

Formula 

Sequence of formatIOn 

La,t dnrsal and anal ra} 

b.furcate 

Peltoral rln m}, . 

Sequence of forma linn 

Formula 

PelVlL f.n m) " 

Sequence of formatlllO 

Formula 

Caudal fin T) p~ 

Pnnllpal laudal ra), 

MH.mum number h)pural , 

Ma\ll11um numberepumls 

Number or ural centra 

eu ml 'p.ne on vertebl'lle 

adJa.:enllo ural> 

Fin 'plOe, or m), elongale 

Head ~plnc~ prc ... cnt In Ian ac 

Predor,al bone, pre,ent 

Oromandll'ular teeth 

O.J ~ 

<;ubordcr 

+ 

.. + 

+ 

.. 

+ 

+ 

.. 

+ 

+ 

... 

.. 

t 

+ 

+ 

+ + 

and Eckardt 191'2: Estabrook ct al 1977; 

1980) such as uscd b} \\'a,hmgllln (19 

attempted exclusi\ cl) \\ nh Ian al fishcs, 

traugh \97 , Pre c.h 

I) ha c rarcl} been 

InLfcased usc of uc\c!opmcntal ostcolog} 

unueNanuing of fishcs Jnu thcir rClJ1IOnship 

hould mlrea c ( ur 

ACK. 0\\ LEDGi\tE :TS 

manu 'ript 

tru~ tI\ eI) fC\ IC\\ cd th m nu 

Flgurc, I and 3 D ugla B 

penultimate draft of thc p per. 

hhng<:r allurat"'}. rapldl}. 

draft ofthl manu lnpt 

IIh 
Kevin M. Howe, College of Fisheries, University of Washington 

(U W), shared his knowledge of fishes with the author and brought 

numerous references to his attention. Howe gave unduly of his time 

and knowledge in the preparation of this review and constructively 

criticized the manuscript. 

Leanne L. Stahl, (formerly of the Department of Oceanography, 

UW), Kathryn 1. Garrison , Fisheries Research Institute, UW, 

Sally L. Richardson , Gulf Coast Research Laboratory, Ocean 

Springs, Miss., and Michael P. Fahay, National Marine Fisheries 

Service CNMFS), Sandy Hook, N.1. , each reviewed various drafts 

of the manuscript and made numerous helpful suggestions. 

Betsy B. Washington CU W) kindly made available to me a draft 

of her M.S. thesis, and read and commented on portions of the 

manuscript. Theodore W Pietsch CU W) read portions of the typescript and Daniel M. Cohen CNWAFC) read the whole of it. 

Thomas Potthoff, Southeast Fisheries Center, NMFS, Miami, Fla., 

generously provided me with a copy of his unpublished manuscript 

on the development of Xiphias gladius. 

One referee (Thomas Potthoff) made numerous helpful comments on a draft of the manuscript which enabled me to eliminate 

errors and to expand the scope of certain portions of it. Any remaining errors in fact or interpretation remain the sole responsibility of 

the author. 

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