TRANSACTIONS E AMERICATH F O N FISHERIES SOCIETY

Volume 122 January 1993 Number 1

Transactions of the American Fisheries Society 122:1-33. 1993 Copyrigh© thy tb e American Fisheries Society 1993

Phytogen Pacifie th f yo c Trout Salmond san s (Oncorhynchus) and Genera of the Family Salmonidae . STEARLEYF . R '. SMITANR . DG H Museum of Paleontology and Museum of Zoology University of Michigan. Ann Arbor. Michigan 48109. USA

Abstract.— Seven genera—Brachymystax. Acantholingua. Salmothymus, Hucho. Salvelinus. Sal- mo, and Oncorhynchus—make up the living Salmoninae. Relationships of 33 extant and 4 fossil salmonid specie subspecied san s were studie basie th f 11 so n d9o characters analyze parsimony db y algorithms. Twelve equally parsimonious trees each requirin step3 g25 s were calculated. Mono- phyly of recognized genera is consistent with all 12 estimates. The earliest branch of the family Salmonidae is the subfamily Coregoninae. Its sister group is the clade including the Thymallinae and Salmoninae. Within the Salmoninae, Eosalmo, from the Eocene of British Columbia, is the sister group of all living genera, as previously shown by Mark Wilson. The living Asian species Brachymystax lenok is the sister species of all other living Salmoninae, as documented by Carroll Norden. Three species of archaic trouts from the Mediterranean area—Acantholingua ohridana. Salmothymus obtusirostris, and Salmothymus (Platysalmo) platycephalus—branch off after Brachymystax but before diversification of all other salmonines. Platysalmo platycephalus Behnke sistee isth r species of Salmothymus obtusirostris places i d Salmothymus.n di an clade Th e beyond the archaic trouts includes four genera in two clades: (1) Hucho plus Salvelinus and (2) Salmo plus Oncorhynchus. Atlantie Th c trout salmond san monophyleti a e sar c group, e Salmo.th d an Pacific trouts and salmons are a monophyletic group, Oncorhynchus. The terms "trout" and "salmon" refer roughl lifo yt e history modesphylogenetio t t no , c relationships. Morphological mitochondriad an l DNA data disagree regardin relationshie gth p of Oncorhynchus clarki (cutthroat trout Oncorhynchuso )t mykiss (rainbow, California golden redband an , d relation e troutsth d )an - shi Oncorhynchusf po gorbuscha (pink salmon Oncorhynchuso t ) keta (chum salmon). Parsimony analysis suggests that Oncorhynchus Pacifie mykiss sistee th th f . o clarki,s cri O salmon f o t no , thoug mykiss. clarki. O h O d an hybridize. Oncorhynchus gorbuscha sistee th s ri specie . nerka0 f so (sockeye salmon), not of keta. though O. gorbuscha and O. keta hybridize. Mitochondrial DNA is interprete s havina d g been transferre introgressioy db n betwee . gorbuschanO . keta,O d an providing misleading evidenc relationshipf eo . Fossil specie Oncorhynchusf so documen minia t - millio6 f o mu e nmmodere ag year th r sfo n specie Pacifif o s c trout salmonsd san .

The family Salmonidae includes three subfam- vica, huchen, taimen, chars, trouts d salman , - ilies—Coregoninae (whitefishes), Thymallinae ons)—widely distributed in the northern hemi- (graylings), and Salmoninae (lenok, mekous, bel- sphere (Norden 1961). Ther strons i e g evidence that eac thesf ho monophyletia s ei c clade nata , - 1 Present address: Department of Geology, Geogra- ural group tha tdescendant e containth f o l sal f o s phy, and Environmental Studies, Calvin College, 3201 its most recent common ancestor Salmonie Th . - Burton Avenue, Grand Rapids, Michigan 49546, USA basae ar .le Euteleosteda i relateEsocoideie th o dt , 1 STEARLEY AND SMITH

Ostariophysi, Argentinoidei, and Osmeroidei fishes, such as osmerids, now placed outside the (Lauder and Liem 1983; Fink 1984; Begle 1991). family Salmonidae). centurieDurino tw e gth s since Previous salmonid phylogenies (e.g., Norden 1961; Linnaeus's classification, ichthyologists have Wilson 1974; Kendall and Behnke 1984; Sanford thoroughly documente classified dan d salmonine 1990) have interpreted the Salmoninae and Thy- diversity. Following is a brief summary of the tax- mallina s sisteea r group f eaco s e h th othe d an r onomic histories of three salmonine assemblages: Coregoninae as the sister group of the clade in- (1) the four genera of morphologically plesiomor- cluding those two (Figure la, b, c). phic "archaic trouts, huchee th ) "(2 n (Hucho)d an subfamile Th y Salmoninae comprises between chars (Salvelinus), more th ) e (3 derive d an d salm- fivd ninan e e extant genera (Figure 1) containing troutd an Salmon s si on Oncorhynchus.d an approximatel specie0 y3 s (Norden 1961; Behnke 1968; Kendall and Behnke 1984). The best known Archaic Trouts genera are Hucho, Salvelinus, Salmo, and Onco- At least four species of archaic trouts in Brachy- rhynchus, which are relatively advanced salmonid mystax, Salmothymus, Acantholingua, Pla-d an fishes. Four other laxa—Brachymystax. Platysal- tysalmo are native to Siberia, China, Korea, Ar- mo, Salmothymus, and Acantholingua—are mor- menia drainaged an ,northease th n so t periphery phologically primitive and their relationships have of the Mediterranean Sea from Dalmatia to Tur- been problematic. The last three are often includ- key. They possess short, broad maxilla shord ean t Salmo.n i d e additionn I , four fossil generd aan dentaries with high coronoid processes, and they several fossil species belongin extano gt t genera have small teeth. The phylogenetic relationships have been recognized. Withou phylogena t y based of these archaic trouts have bee nproblea - mbe on broad evidence fro l speciesmal directioe th , n cause they share primitive character- s ge wit e hth of evolution and the positions of the fossils and nus Salmo. Norden (1961) recognized that problematic taxa relative to the more advanced Brachymystax is morphologically and phyloge- genera canno knowne tb relationshipe .Th charf so s netically intermediate between Thymallusd an (Salvelinus) to other salmonines are also crucial more derived salmonines, base severan do l fea- classificatioe th o t f troutno salmonsd san . Some tures. However, other systematists have placed systematists (e.g., Norden 1961) have considered Brachymystax as the sister group of Hucho, be- Salvelinus sistee th s ra lineag clada f eo e including cause they share a unique vomerine tooth pattern Salmo d Oncorhynchus,an whereas others (e.g., (discussed below). Kendal Behnkd an l e 1984) have placed Salvelinus Salmothymus is sometimes considered to in- close Huchoo rt Brachymystax.d an clude two species, 5. obtusirostris (Heckel), the Although salmonid biologists agree that Atlan- Dalmation trout or "mekous," and S. (Acantho- tic salmon Salmo salar and brown trout Salmo lingua) ohridanus (Steindachner), the "belvica," trutta are closely related to Pacific trouts and endemic to Lake Ohrid in Yugoslavia. Behnke salmons, they have disagreed about the classifi- (1968:10) noted: "although vital to any compre- catio f Pacifino c trouts. Regan (1914 d Vlaan ) - hensive phylogenetic study of salmonid fishes, the dykov (1963) drew attention to the closer rela- statu Salmothymusf so neves ha r been firml- yes tionshi f Pacifio p c trout o Pacifit s c salmons tablished." Steindachner's classifications of Sal- (Oncorhynchus) tha Atlantio nt c trou salmod tan n mothymus obtusirostris demonstrate the ambigu- (Salmo). Traditionally, however, Pacific trouts ity indicate morphologys it y db firse h : t classified have been classified in Salmo, thus making Salmo the mekous as a grayling, Thymallus microlepis an unnatural group—paraphyletic—because it does (1874) t latebu , r place Salmon i t di (Steindachner no s descendantt it includ f o l al e s (Smitd an h 1882). Berg (1908:505) calle Salmothymust di - ob Stearley 1989). In the present paper, the relation- tusirostris. remarking that its features were inter- ships of the species of Pacific trouts and salmons mediate between Brachymystax and Salmo: "Sie eaco t h othe treatee contexe r ar phy e th th n d i -f to bildet eine besondere Gattung, welch n Bineei - logen l fossi al Recend f yan lo t gener f salmonao - deglied zwische eben nde n genannten Gattungen ines. [i.e., Salmo and Brachymystax] darstellt." Had- zisce (1961) first recognize fundamentae dth l dif- Histor Salmof yo Troud nan t Classification ferences between obtusirostris ohridanusd an d an Salmo, as proposed by Linnaeus in 1758, in- allocated the two species to two monotypic gen- cluded all salmonines then known, as well as thy- era— Salmothymus obtusirostris and Acantholin- mallines and coregonines (and some groups of gua ohridana. Behnke (1968) considered Sal- SALMONID PHYLOGENY

FIGURE 1 .—The major phylogenetic hypotheses regarding the Salmonidae (rearranged to comparable format): (a) Norden (1961) Wilso) (b , n (1974) Kendal) (c , Behnkd an l e (1984) Dorofeyev) (d , a (1989) daggee Th . r indicatesa fossil taxon; dotted lines indicate uncertainty.

mothymus Acantholinguad an subgenere b o t f ao Huchen Charsand Salmo. Svetovidov (1975) placed Acantholingua ohridana in Sal mothymus, a classification that has huchee Th describes nwa Linnaeuy db s (1758) been widely followed. as Salmo hucho and placed in the subgenus Hucho Behnke (1968) described another species of ar- by Gunther (1866). Jordan and Snyder (1902) el- chaic trout, Salmo (Platysalmo) platycephalus, evated Hucho to generic rank and described a sec- from Turkey. He saw evidence that Platysalmo, ond species, H. perryi. Vladykov (1963) created like Salmothymus and Acantholingua, had di- the subgenus Parahucho for Hucho perryi. Lindsey verged from European Salmo long before differ- (1964) called attention to broad similarities be- entiation of modern Salmo salarand S. trutta had tween Hucho Salvelinus.d an huchet Bu n wer- ere occurred classifiee h t bu , d the Salmo.mn i Simi- garde closs da e relatives of Brachymystax Shay b - larly, "Salmo" ischan from Armenia and "Sal- poshnikova(1968, 1975), Holdik (1982a, 1982b), " carpiomo fro mArchaie b Italy yma c trout- sre d Holcian t ale k . (1988). Kendal d Behnkan l e late o Salmothymust d obtusirostris. S d an (1984) treated Brachymystax plus Hucho clada s a e platycephalus. Such a broad concept of Salmo related to Salvelinus. makes a genus containing relatively unrelated spe- Chars, Salvelinus, are a monophyletic group with cies—a polyphyletic assemblage. many holarctic species (see Behnke 1972; Balon STEARLEY AND SMITH

1980, 1984). Diverse proposals have been made Giinther (1866) elevated Oncorhynchus- ge o t for recognizing taxonomic structure - withige e nth neric rank, rejected Suckley's characters, redefined nus (Vladykov 1963;Cavender 1978, 1980, 1984; Oncorhynchus to be based on a longer anal fin Cavende Kimurd ran a 1989; Phillip t alse . 1989; (with more than 14 rays; he was unaware of On- Kendall and Behnke 1984; Grewe et al. 1990). corhynchus masou, which has 11-13 anal rays) so Recently a new genus of char has been described that it applied to Pacific salmon but not trout, and from Lake El'gygytgyn in Siberia and given the classified males and females of the same species name Salvethymus (Chereshnev and Skopets together continuee H . classifo dt y Pacific trouts, 1990). huchen, and chars in Salmo. Jordan and Gilbert (1883) sorted out some of the confusion resulting Trouts Salmonsand from Walbaum's, Richardson's, and Suckley's Trout salmond san s occu northern ri n Atlantic synonymous species names, but the diagnosis of and northern Pacific drainages. Formal classifi- Oncorhynchus remained ambiguous even to Jor- catioAtlantie th f no c Sal truttao m (brown trout) dan. In 1892 he described the Kamloops rainbow Salmod an salar, (Atlantic salmon) date from Lin- Oncorhynchusn troua s a t relate . tshawyts-O o dt naeus (1758). Pacific basin trouts and salmons had cha (Jordan 1892), but assigned it to Salmo a year already been discussed in an unpublished manu- later. The identity of the east and west Pacific scrip fishen o t f Kamchatkso Geory ab g Wilhelm rainbow trout remained confused unti wore th l k Steller; after Linnaeus's work, Johann Walbaum of Behnke (1966 especialld )an y Okazaki (1984). (1792) formally named Steller's species in Salmo: The cause of the generic ambiguity was dis- Salmo mykiss (rainbow trout) . kisutch5 , (coho cerneearle th yn d i decade f thiso s centur. C y yb salmon), S. tshawytscha (chinook salmon), 5. keta . Regae BritisT th f no h Museum. Regan (1914: (chum salmon), 5. nerka (sockeye salmon), and S. 406) noted that "examination of the skeletons gorbuscha (pink salmon). Walbaum apparently leave doubto sn tha Pacifie tth c species (Steelhead, worked from Pallas* translatio Steller'f no s manu- Rainbow Trout, Quinnat Salmon, etc.) for mnata - scripts, as published in Pennant's "Arctic Zoolo- ural group that differs in several characters from gy" (Briggs 1965). Richardson (1836) rediscov- the Salmon and Trout of the Atlantic." However, ered and named these same taxa Salmo gairdnerii Americans (e.g., Jordan and Evermann 1920) ig- (rainbow trout), S. tsuppitch (coho salmon), S. nored Regan and continued to group Pacific trouts quinnat (chinook salmon), S. consuetus (chum with Atlantic trouts and salmon in Salmo on the salmon) . paucidensS , (sockeye salmon). S d an , basis of the difference in number of anal rays. From scouleri (pink salmon basie th f specimen so n o ) s Jordan and Evermann (1896) to Jordan et al. from northwestern North America. Among Rich- (1930 througd )an h four edition Americae th f so n ardson's other discoverie Salmos swa clarki (cut- Fisheries Society's "List of Common and Scien- throat trout), which occur ease s onlth t n sidyo e tific Name Fishef so s fro Unitee mth d Stated san of the Pacific. Canada," American ichthyologists groupee th d In 1861, Suckley renamed severa Pacifie th f o lc Pacific trouts wit browe hth n trou Atlantid an t c trout and salmon again and proposed the subge- salmo genue th n si Salmo, although workers such nus Oncorhynchus (type species . gorbuscha),S r fo as Neave (1958), Behnke et al. (1962), Rounsefell those anadromous Salmo wit a "permanentlh y (1962) d Behnkan , e (1972) recognize close dth e hooked snout enlarged "an d teeth (Suckley 1861). relationship between Pacific trout and Pacific s suggestioHi s amplifiewa n a posthumou n i d s salmon. work (Suckley 1874)lattee th n rI . paper cleas i t ,i r Tchernavin (1937, 1938a) also rejected Regan's that his conception of Oncorhynchus was based classification and offered a notable logic in support primaril breedinn yo g males. Mature males were of his argument. Tchernavin (1937:236) used usually included under the subgenus Oncorhyn- shared primitive characters for diagnosing genera: chus while immatur d femalean e individualf o s "Som thesf eo e [skeletal] elements see retaimo t n the same species were not; for example, the chi- old ancestral characters and thus afford a guide to nook salmo artificiallnwas y divided into Onco- the natural arrangement of families and genera; rhynchus cooperi and Salmo richardi. Suckley while other elements of the skeleton, mostly those considered steelhead, coastal cutthroat troutd an , belonging to the investing bones, change with the female chinook salmon, coho salmon, chum salm- developmen speciee th presenf d o t san t clear dis- on, pink salmon, and sockeye salmon to be "salm- tinctions for determining species." Although on," but not in Oncorhynchus. Tchernavin was trying to discover natural groups, SALMONID PHYLOGENY

his criteria were inconsistent with Regan's phy- his phylogeny of the salmonine fishes differs from logenetic criteria. The distinction is that Tcher- thos othef eo r workers. navin sought genealogical evidenc e unth - n i e Vladykov (1963:496) regarded Parasalmo (type changed anatomy, whereas Regan used shared species clarki) to be the same as the group con- specializations as evidence of relationship, as later taining the fossil trout Rhabdofario lacustris. But formalized by Hennig (1966). The former method perhaps because the latter is a fossil, he missed result subjectiva n si e classification base graden do s the nomenclatural priority (Cope 1870) of the of advancement; the latter leads to a classification name Rhabdofario Cope 1870 over Parasalmo of monophyletic group f sequentiallo s y related Vladykov e clad1963th s takef i ei , includo nt e clades. Character evidence documente Tchery db - bot rainbowe hth trout (mykiss) cutthroad an t trout navin include unforken da d rostral cartilagd ean (clarki). Relationshi f Rhabdofariopo lacustriso t the lac dorsaf ko l fontanelle Pacifie th n si c salmon extant Pacific trout beed sha n establishe Uyeny db o chondrocranium. and Miller (1963) also owh , place e specieth d s Norden's (1961) review of the osteology of the with Pacific troutgenue th n ssi Salmo (and changed grayling (Thymallus) summarize charace th l dal - the species nam copeio et becaus combinatioe eth n ter evidence for sequestering Pacific salmons in Salmo lacustris beed ha n use Linnaeus)y db . Vla- Oncorhynchus'. "widely separated palatine and dyko Gruchd van y (1972) gave separate diagnoses vomerine teeth; postorbitals contacting preoper- for Parasalmo d Rhabdofario.an Cavended an r cle; no ascending process of premaxilla; opisthotic Miller (1972) compared their new fossil genus touches prootic aduln i ; dorsao n t l fontanelles" Smilodonichthys o Oncorhynchus,t Salmo (in- (Norden 1961:753). These characters were sub- cluding Pacific trouts), and Rhabdofario. and in sequently use o diagnost d e Oncorhynchus (see 1982 recognized Parasalmo as a subgenus of Sal- Kendal d Behnkan l e 1984). They wil e examb l - mo. Smith (1975) used Rhabdofario to emphasize ine detain di l below because they also applo yt differences betwee fossie nth l species, lacustris.d an some large Pacific trouts and so the group thus the recent trouts in western North America. Ken- diagnosed makes Pacific trouts paraphyletic (Smith dalBehnkd an l e (1984) regarded Rhabdofarios a and Stearley 1989), that is, an assemblage that a fossil clade apart from Parasalmo but confused doedescendants s t includit sf no o l eal . the species each contains. The current study at- Most data accumulated since Tchernavin's tempt diagnoso st e monophyletic lineage troutf so s time—meristic (Rounsefell 1962), osteological and salmons, while resolving the nomenclatural (Vladykov 1963; Behnke 1972; Cavender and conflicts among Salmo. Oncorhynchus. Parasal- Miller 1972, 1982; Smith and Stearley 1989; San- mo, Smilodonichthys. and Rhabdofario. ford 1990) moleculad an , r (Ber Ferrid gan s 1984; Grew alt ee . 1990)—support Regan. They indicate thaPacifie th t c trout Pacifid san c salmons forma Methods unified clade separate from Atlantic salmon and Our approach to the classification problem is trout t mosBu . t workers have been reluctano t t founde e principlth n o d e that biological classifi- upset the established nomenclature, sacrificing cation should reflect, if possible, phylogenies historical accurac potentiad yan l predictabilitr yfo (Darwin 1859:486); named groups should corre- stability (Smith and Stearley 1989). spond to monophyletic clades, which include all Vladykov (1963), however, proposed a com- of the descendants of a common ancestor. Un- promise solution—a new genus or subgenus (the natural groups, which exclude derived relativer so original designatio ambiguous)s ni , Parasalmo,r fo include nonrelatives (paraphyleti d polyphycan - the Pacific trouts. Vladykov and Gruchy (1972) letic assemblages, respectively) admissiblnot ,are e designated S. clarki as the type species of the sub- in suc ha classification f SalmoI . s madi e poly- genus Parasalmo in Salmo. This solution received phyleti paraphyletir co inclusioe th y cb specief no s recent support (e.g., Cavende Milled an r r 1982; (e.g., obtusirostris r clarki)o more closely related Kendal d Behnkan l e 1984:figur ; Dorofeyev1 e a otheo t r lineages, than such species- musre e b t 1989). However, placing Pacific trouts in a new moved from Salmo and classified with their rel- subgenus of Salmo does not solve the problem, atives. whic thas hi t Pacific trout e relatesar Onco-o dt Monophyletic group discoveree sar diagd dan - rhynchus. t Salmo.no Baton's (1984) analysis i s presencnosee th y db sharedf eo , derived character consistent with the Vladykov classification, but states—synapomorphies (Hennig 1966). Shared STEARLE SMITD YAN H

primitive characters—symplesiomorphies—such Jollie (1984, 1986), Sanford (1990), and Begle s use a Tchernaviy db n (1937) carr informao yn - (1991). tion abou phylogenetie th t c (i.e., branching) rela- Character states were polarize y includinb d g tionships of the evolving lineages in the group. three taxa outsid Salmonidaee eth t relatebu , o dt Homoplasies (convergently or introgressively ac- it, as reference points (outgroups) to indicate quired shared character states and states acquired primitive character states. Although general rela- by character reversal understooe ar ) false b eo dt tionships of basal euteleost families are under- evidence regarding branching sequence and are stood (Gosline 1960; Rosen 1974, 1985; Fink and identified by their noncongruence (disagreement) Weitzman 1982; Fink 1984; Howe Sanford san d with other characters in the study. (Nonindepen- 1987; Begle 1991 singlo )n e closest sister grouf po dent homoplasies, suc s mighha t arise from par- the Salmonidae has been identified. Primitive out- allel reductio sizn n i r introgressiv eo e hybridiza- extangroupe th e ts ar osmeri d genus Thaleichthys. tion, are possible sources of error; note the the extant umbrid Novwnbra hubbsi. plesiod an - discussion of apparently paedomorphic Acantho- morphic ostariophysan genus - Chanos.Os e Th lingita ohhdana d introgressean d Oncorhynchus merida closese Ostariophysd th f ean o t o tw e ar i gorbuscha below. parsimone th n I ) y methode sw extant sister groups to the Salmonidae (Gosline employ, diverse homoplasies are expected to be 1960; Fink 1984; Rosen 1985). Within the os- outweighed, as evidence, by characters whose con- merid fishes, Thaleichthys consideres i plee b -o dt gruenc a resul s i ef thei o t r shared evolutionary siomorphic (Weitzman 1967; Howes and Sanford history. The choice between alternative phyloge- 1987; Begle 1991 d henc choses an )e th ewa s na netic trees is therefore made by calculating the source of osmerid character information. Similar- branching sequence that account observee th r sfo d ly, the gonorhynchid Chanos represents a ple- patter charactef no r evolution wit fewese hth - re t siomorphic member of the Ostariophysi (Fink and versals or convergences—or in terms of the par- Fink 1981). The genus Novumbra was considered simony hypothesis, the branching sequence that the plesiomorphic sister grou f othepo r umbrids require assumption c fewese ho sth d a t explaio st n by Wilso Veilleud nan x (1982)thref o e e outUs . - the observed character state distributions. groups provide e algorithmth s s wite inforth h - One hundred nineteen characters were assessed mation necessary to polarize the character states on representative extan3 fossi4 3 d f so l an t taxo- regardless of initial code assignments, but other nomic units (Table 1; Appendix). Algorithms pro- basal euteleosts provided perspective on character gramed by David Swoffbrd (PAUP 2.4—Phylo- state codes and are used to assign 0 to represent genetic Analysis Using Parsimony Jamed )an . sS possible primitive states, and 1, etc., to represent Farris (HENNIG86) were used to estimate the more advanced states in Table 1 and Appendix 1. most parsimonious trees (Swofford 1985; Farris Cretaceous euteleosts Gaudryella and Humbertina 1988). Branch-swapping algorithms wer- em e (Patterson 1970 Leptolepisd )an (Cavender 1970) ployed, with Farris optimization procedureso t , are additional sources of information about prim- identify the shortest trees. Nelson consensus trees itiveness Coregoninae Th . Thymallinad ean e ear were calculated when several most parsimonious morphologically plesiomorphic salmonids. The trees (found by both programs) were of equal plesiomorphic coregonines Prosopiurn coulteri. length. Coregonus huntsmani. and Stenodus leucichthys Skeletonized, cleared-and-stained, dissected dan thymalline th d an e Thymallus arcticus include ar - fossil specimens were examined. Many characters eoutgroups da s neares Salmoninaee th o t . Char- used herein have been identified in prior studies, acter state polarizationd san listee sar Tabln di e but all relevant anatomical material was reex- 1. Code values are assigned to character states in characterw aminene d dan s were discovered.e W a simplified scheme, wit usuall0 h y referrino gt acknowledge a large debt to prior character dis- primitive th e stat d wite an (sometime 1 h d an 1 s covery Svetovidoy b - v (1936, 1975), Tchernavin 2) representin derivee gth d state(s). Evolution ni (1938a. 1938b), Miller (1950, 1972), Norden two opposite directions from an ancestor was cod- (1961), Behnk t alee . (1962), Hikita (1962), Vla -derive2 d an d0 froes da m 1. Directional infor- dykov (1962, 1963), Needham and Card (1964), matio multistatn ni e character s includewa s n di Behnke (1968), Shapozhnikova (1968), Cavender the coding (additive coding) when we had evi- (1970, 1980), Cavender and Miller (1972, 1982), dence that intermediac morphologn yi y required Scot Crossmad an t n (1973), Wilson (1977)- Do , intermediac historyn yi . Character dat pree aar - rofeyeva (1978, 1989), Holcik (1982a, 1982b), sented in tabular form in the Appendix. SALMONID PHYLOGENY 7

TABLE 1. —Description of 119 salmonid character states. Assignments of numerical character states (bold digits) tabulatee ar thn di e Appendix. Generally denote0 , primitive sth denot 2 d an ee 1 statederive d an , d states. 1. Dorsal chondrocranium. Temporal fontanelles remain open throughout life (0) or close during late ontogeny (1) (Figure 2: see Tchernavin 1937) 2. Dermelhmoid. Paired (0), single and median with posterior separation (notch) (1), or single and median with no posterior separation (2) . 3 Dermethmoid. Short to moderately r extremel o lon ) g(0 y foulongo t p r u ,time s widt (Figur) alshc (1 se o ; e3 Norden 1961) . 4 Dermethmoid. Overlapping frontal lyind an s g between nasalr contactino ) s(0 g frontal t withoubu s t broad overlap (1) 5. Dermethmoid. Without prominent midlength constriction (0) or with constriction, spearhead-shaped (1) 6. Dermethmoid. Not broad and blunt (0) or very broad, in shape of blunt diamond (1) (Sahno, Figure 3) 7. Dermcthmoid. Not "A-shaped" (0). "A-shaped" with narrow taper (1), or with widely (greater than 40°) divergent, posterior wing (Figur) s(2 ) e3 8. Dermethmoid. Without anterior extension in breeding individuals (0) or with anterior extension in breeding individuals (l)(Vladykov 1962) . 9 Ethmoid. Presen absenr o ) (0 t t (1). (This median chondral ossification, underlyin dermethmoide gth oftes i , n terme "hypethmoide dth " by salmonid systematists [e.g., Norden 1961] t thi generan bu i ,s t namno ls ei use. We adopt the term advocated by Harrington 1955 rather than the "supraethmoid" of Patterson 1975, because the latter name has often been used synonymously with "dermethmoid.") 10. Lateral ethmoids. Deeper dorsoventrally than r widtwido ) he(0 approximately equa maximao t l l dept) h(1 11. Postemporal fossae roofed (0) or open (1) 12. Frontals t includeNo . flooe s parth f thd a o rf e o t posttemporal r fossaincludeo ) flooe (0 pars th f d a o rf o t these (1) 13. Frontals. Not widely expanded above the autosphcnotics (0) or expanded laterally, covering the autosphen- otics(l) 14. Frontals and parietals. Parietals not flanking frontals (0) or flanking frontals that are extended posteriorly along the midlin ) (Nordee(1 n 1961) 15. Frontals. Without depressio t posteriona r midlin r wito ) h e(0 depressio ) n(1 16. Frontals. Without anterior shelf-like expansion above orbit (0) or with shelf above orbit (1) (Figure 4) 17. Frontals contacn i t No .t with epiotic r contactino ) s(0 g epiotic largn si e individual) s(1 18. Sphenotic. Anterior ramus thin and directed laterally (0) or stout and directed anteriorally (1) (Figure 5) 19. Pterotic. With short hyomandibula fossa, extending half the length of the ptcrolic (0), or fossa extending the entire lengtpterotie th f h) o (Figur c(1 ) e5 20. Epiotics. With flat posterior surface (0) or surface with sulcus (1) 21. Epiotics. Without stout conical dorsoposterior processe r wito ) h s(0 processe ) s(1 22. Supraoccipital. Crest short, not as long as anterior-posterior dimension of supraoccipital (0), or as long as anterior-posterior dimension of supraoccipital (1) 23. Intercalar. With small otic ramus (0) or with long otic ramus, typically contacting the prootic (1) (Figure 5) . Prootic24 . Narrow anteroposteriorl anteriod yan r branc f trigeminofaciaho l nerve exiting through foramen no anteromcsial margi expander o ) n(0 d antcroposteriorl nervd yan e exiting through forame lateran no l margin (1) (Figure 5) 25. Orbitosphenoid. Absen r preseno ) (0 t t (1) . Orbilosphenoid26 . With anterior emarginatio r withouo ) n(0 t emargination (1) 27. Orbitosphenoid. Left and right halves fused ventrally, forming a Y-shaped cross section (0), or unfused. broadly ova crosn i l s sectio) n(1 28. Orbitosphenoid. Not in form of spongy ball (0) or in form of spongy ball (1) 29. Parasphenoid. In sagittal profile, flexed (0) or straight (1) 30. Parasphenoid. Not extending posteriorly to the posterior edge of the basioccipital (0) or extending to posterior edge of basioccipital (1) 31. Posterior parasphenoid. Flat in cross section (0) or with high vertical walls flanking the posterior myodome ) (Figur(1 ) e5 32. Parasphenoid. Basisphenoid process of parasphenoid not ossified (0) or stout and ossified (1) . Occipita33 l condyle. Simpl involvind ean g onl basioccipitae yth l (0), tripartit involvind ean basioccipitae gth l and processes from the two exoccipitals (1), or secondarily fused (2) (Cavender and Miller 1972) . Vomer34 . Dentition presen r teeto ) h (0 t absen r vestigiao t adultn i l ) s(1 35. Vomer. Short (0) or long, extending posteriorly to the lateral ethmoids, and with teeth on shaft (1) . Vomerin36 e longitudinal tooth row extendint No . g to posterior edg vomef elongr o o ) ,r(0 extendin posteriogo t r edge of vomer (1) 37. Vomer. Without prominent anterior transverse tooth row (0) or with such row (1) (Figure 6) . Vomer38 . Without teet posterion ho r extension (crestvomerine th f o ) e capitulu r wito ) hm (0 suc h teet) h(1 (Figur) e6 . Vomer39 . Without anterior extensio breedinn ni g maler wito ) h s(0 suc h extensio) n(1 . Vomer40 . Teet t deciduouhno r deciduouo ) s(0 typicalld san y lost during breeding migratio) n(1 \ STEARLEY AND SMITH

TABLE 1.—Continued.

41. Hyomandibula. Dorsolatcral surface narrow with adductor r broaridg o dish-shaped ) ed(0 an d without trace adductof o r ridg ) (Figure(1 ) e7 42. Metapterygoid. Positioned between quadrate and symplectic and in broad contact with symplectic (0) or positioned more dorsally with minimal contact with symplectic (1) (Figure 7) . Metapterygoid43 . Extending dorsall middlo yt f hyomandibuleo r extendino ) a(0 g nearlpterotie th o ) yt c(1 (Figur) e7 44. Mesopterygoids. Bearing teeth (0) or toothless (1) 45. Mesopterygoid. In marginal contact with metapterygoid and quadrate (0) or extended posteriorly, broadly overlapping metapterygoid and overlapping quadrate (1) (Figure 7) 46. Palatine. Well-toothe teetr o ) hd (0 vestigia absenr o l ) (1 t 47. Palatine. Premaxillary process with no or small posterior crest (0) or with long blade-like crest (1) (Figure 7; also see Smith and Stearley 1989, figure 1) . Quadrate48 . Angle between anterio posteriod ran r margin greater o acutr o ° (Figur) ) s90 e(1 r(0 ) e7 49. Maxilla. Bearing teeth (0) or teeth absent in adults (1) (Norden 1961). 50. Maxilla. Short, not extending posterior to orbit (0), or long, extending posterior to orbit (1) 51. Maxilla. Bladelik ventrad ean l edge convex (0), straigh r slightlo t y concave (1) r stronglo , y arche) d(2 52. Maxilla. Flat in cross section (0), ovate in cross section (1), or round in cross section (2) Maxilla53. . Premaxillary process extending dorsally less thafro mai10° mnthe nmaxill the axior of s (0) a extending dorsally at angle of 10° or more from the main axis of the maxilla (1) (see Smith and Stearley 1989) 54. Maxilla. Premaxillary process not projecting below axis of maxilla (0) or palmate and extending below the maxille axith f ) (seso a(1 e Smit Stearled han y 1989) 55. Premaxilla. Toothed (0) or vestigial teeth in adults (1) (Norden 1961) . Premaxilla56 . Without enlarged breeding r wittusko ) h s(0 enlarge d breeding tusk (Vladyko) s(1 v 1962) 57. Premaxilla. With rudimentary ascending process (0) or with broad ascending process (1) . Premaxilla58 . Ascending proces t deflectesno d posteriorl r deflecteo ) y(0 d posteriorl typicalld yan y archen di breeding males (1) 59. Premaxilla. Without "thin crest" (sensu Vladykov r wit1962o ) h )(0 thi n cres) (1 t . Premaxilla60 . Teeth without dark ename r wito ) h (0 ldar k ename ) (Cavende(1 l Milled ran r 1972) 61. Premaxilla. Without substantial mesial pocke r rostrafo t l cartilag r wito ) h e(0 pocke ) (se(1 t e Smitd han Stearley 1989) 62. Premaxilla. Without strong process mesial to the rostral cartilage pocket (0) or with process (1) (see Smith Stearled an y 1989) . Supramaxilla63 . Broa ovatd dan e (0), thilanceolatd nan e (1) r lon inflecteo .d gan ) d(2 64. Dentary. Without stout and deep body anterior to the Meckelian groove (0) or deep anterior to the Meckelian groove (1) 65. Coronoid process of dentary. Rising steeply from the symphysis at an angle greater than 45° such that the highest portion of the mandible is positioned close to the symphysis (0), rising less steeply such that the highest portion of the mandible is positioned midway (1), or rising at a very shallow angle such that the highest portio mandible th f no positiones ei d posteriorl (Cavende) y(2 Milled ran r 1972) . Dentar66 angular-articulard yan . Coronoid proces dentarf so coronoid yan d angular-articulaf rao ms u closn ri e fit (0) or gap between these (1) (Smith and Todd, in press) . Dentary67 . Without anterior cartilaginous expansion (kype breedinn i ) g maler wito ) h s(0 kyp e (1). (Although the term "kype s use"i salmonin i d d literatur e hookin th o refet e o t rf eithe go r uppe r loweo r w ja r accompanying breeding status, Morton 1965 demonstrated that this word historically strone referth o sgt mandible.e hooth n ko ) . Dentary68 . Without extreme developmen r witkypf o o t) h e(0 extrem e developmen kypf o t) e(1 69. Dentary. Teeth well socketed (0) or not well socketed, deciduous in breeding individuals (1) 70. Dentary and maxilla. Without dark enameloid on interior of teeth (0) or with dark enameloid (1) (see Vladykov 1962:52) 71. Angular-articular. Posterior process extending horizontally (0) or at an angle to the horizontal (1) 72. Retroarticular. Ventral and suture with angular-articular at low angle (0), suture at angle higher than 45° (1), r suturo t higea h angl retroarticulad ean r mesia angular-articulao t l ) r(2 73. Supraorbital. Long and bordering most of the dorsal surface of the orbit (0) or short and bordering the anterior third of the dorsal surface of the orbit (1) 74. Supraorbital t contactinNo . dermosphenotie gth contactinr o ) c(0 dermosphenotie gth ) c(1 75. Supraorbital(s). Single Supraorbital (0) or multiple (1) 76. Postorbitals. Long and covering hyomandibula (0) or short and covering less than half the hyomandibula (1) (Smith and Stearley 1989) 77. Infraorbitals. Typically 6 (0) or restricted to 5 (1) (i.e., circumorbitals typically 8 I0| or restricted to 7 11)) 78. Second infraorbitals. Second infraorbital blade-like (0) or thin and tubular (1) (Smith and Stearley 1989) 79. Postorbitals. Not divided into two series (0) or divided into anterior and posterior series (1) . Suprapreopercle80 . Absen r preseno ) (0 t t (1) SALMONID PHYLOGENY

TABLE I.—Continued.

81. Preopercle. Ventral limb long, two-thirds the length of dorsal limb (0), reduced, half the length of dorsal limb (1) greatlr o , y reduced, less than hal lengte fth dorsaf ho l lim (Figur) b(2 ) e8 82. Preopercle. Dorsal limb not deep, approximately 20% of its length (0), or expanded posteriorly, ranging up to 30% or more of its length (1) (Figure 8) . Subopercle83 . Deep, two-third dees sa wids pa e (0) shallowr ,o , simila shapn ri branchiostegao et ) (1 l 84. Extrascapulars. Tabular (0) or tubular (1) . Media85 n basihyal denticles. Presen absenr o ) ) (0 t(1 t . Basihyal86 . Without teet perimeten ho witr o ) h r(0 stou t teeth around perimete) r(1 . Basihyal87 . Blunt anteriorl r thipointed o n) an y(0 d anteriorl (Vladyko) y(1 v 1962) 88. Basibranchial plate. Present (0) or absent (1) (Norden 1961) 89. Basibranchial plate. With teeth (0) or without (1) (Norden 1961; Behnke 1972) 90. Anterior ceratohyal. Imperforate (0) or perforate (1) 91. Anterior ceratohyal. Slender and slightly constricted (0), or rectangular, length : depth ratio 2.5 or less (1) (Figur) e9 92. Branchiostegals. Fewer than 10 (0), 10-13 (1), or more than 13 (2) 93. Vertebral number. Mean number less than 61 (0), 62-65 (1), or more than 65 (2) 94. Caudal skeleton. Posterior hemal spines, parahypural, and first hypural lacking peg-and-socket connections witr o ) h (0 peg-and-socket connections (1) 95. Caudal skeleton. With ossifications ("tendon bones" urostyle th withour o n )i ) e(0 t urostyle ossification) s(1 96. Caudal skeleton. First uroneural not amplified into a large fan-shaped stegural (0) or amplified into a fan- shaped stegura) (1 l 97. Caudal skeleton. With complete neural arch and spine on preural centrum 2 (PU2) (0) or with spine detached from arc) h(1 98. Caudal skeleton. With three epurals (0) or two epurals (1) (Norden 1961; Vladykov 1962) . Dorsa99 raysn fi l . Fewer tha r morno ) 1e7(0 than ) 17(1 100. Numbe gilf ro l raker firsn so t arch. More tha r fewerno ) 16(0 than ) 16(1 101. Gill rakers. Mean coun r vero t ) beloy (0 high 5 w2 , abov) (1 5 e2 102. Lateral line scales. Roughly circular (0) or very elliptical, reduced to little more than the nerve tube (1) 103. Karyotype. Dipioi tetraploir o ) d(0 ) d(1 104. Nostril flaps flae r nariappe On . flapo l ) (Hubbopenintw s(1 r o Lagled ) san g (0 r 1947) 105. Pyloric caecae. Fewer than 20 (0), 20-70 (1), or more than 70 (2) 106. Dorsal trunk. Without pronounced hum breedinn pi g maler wito ) h s(0 hum ) p(1 107. Dorsal trunk. Without extreme developmen humf witr o to ) h p(0 extrem e developmen humf o t ) p(1 108. Nuptial tubercles. Presen r abseno ) ) (0 t (1 t sizeg 109Eg . .Les (0)m s m .tha 3.5-4.0 n 3. (1) m greater 5 m diameteo ,n i m r m (Norde) tha 5 r(2 n4. n 1961) 110. Coloration. Without vertical bars ("parr marks") in juveniles (0) or with vertical bars (1) 111. Coloration. Without pale r witspoto ) h s(0 pal e spots (1) 112. Coloration. Without cutthroat mark (0) or with cutthroat mark (1) 113. Coloration. Without yellow cutthroat r witmaro ) h k(0 yello w cutthroat mar) k(1 114. Coloration. Without dark patch on border of adipose fin (0) or with dark patch on border of adipose fin (1) 115. Coloration. Without vermiculated spots on back (0) or with vermiculations (1) 116. Coloration. Without X-shaped spotwitr o ) hs (0 X-shape d spot) s(1 117. Coloration. Dorsal, anal, and pelvic fins without white tips (0) or with white tips (1) 118. Coloration. Caudal fin without red anterior edge (0) or with red anterior edge (1) 119. Nostrils. Without minute papillae around margins (0) or with papillae around margins (1) (Stanford 1990)

consensue th s1e 2treth equallf eo yResult parsimonious s Twelve equally parsimonious trees, requiring tr<*s, calculated wite CONTREth h E program 253 steps, resulted froe computer-assistemth d (Swofford e Nelso1985th d n)an consensus tree analyse PAUy sb HENNIG86d Pan consise Th . - °Plion in HENNIG86 polytomiee .Th Figuren si s tency consistenindew eac0.54r lo s xfo e h wa .Th - 10-1 consistene 2ar t wit equalle hth y parsimoni- cy inde consequenca s xi large th ef e o numbe f ro ou * solution thren si e areas .relationshipse (1)Th taxinclusiod aan manf no y homoplasti t poc-bu of Acantholingua ohridana otheeithee e th ar ro rt tentially informative characters, such as meristic archaic trouts or to all salmonines above Brachy- characters 1e 2 tree.Th similae sar most ra t points, mystax (Figur specieo e Tw 10) ) Salvelinus,f so .(2 generie Th c relationship basee s ar chose s du y nb leucomaenus fontinalis,d an have equally parsi- on monophyletic groups that are consistent with monious alignments to another node (Figure 11). topologe th 1e 2th treesf yo . Figures 10-12 depic Fou) (3 rt fossi recend an l t relative f Oncorhyn-so 10 STEARLEY AND SMITH

nr

FIGURE 2. —Neurocranium, dorsal bones remove shoo dt w fontanelle cartilagen si , anterio ) Sahno(a . rup salar, after Tchernavin (1937 :) Oncorhvnchus figur(b ; 1) e mykiss. after Tchernavin (1937 :) Oncorhvnchusfigur(c ; 4) e mason. Oregon State University Collection 8087 Oncorhynchus) ;(d tshawytscha, after Tchernavin (1937: figur. e2) Abbreviations , dorsadf : l fontanelles; idf, incomplete dorsal fontanelle; ir, intermediate rostrum; ndf dorsao n , l fontanelle in adults; nr, notched or divided rostrum: ur. undivided rostrum. SALMONID PHYLOGENY 11

Co) FIGURE 3. — Dermethmoids, dorsal view, anterio ) Thvmallus(a . rup arcticus, UMMZ (Universit f Michigayo n Museu Zoologyf mo ) 186233S Brachymvstax) (b ; lenok, UMMZ 172491 ) Huchoperryi.(c ; UMMZ 187613S) (d ; Salvelinus namaycush. UMMZ 203837S; (e) Salmo trutta. UMMZ 183694S; (0 Oncorhynchus clarki. UMMZ 181728S; (g) Oncorhynchus mykiss. UMMZ 213375S; (h) Oncorhynchus mykiss (redband), UMMZ 219575S; (i) Oncorhynchus rhodurus. UMMZ 208141S; (j) Oncorhynchus kisutch. UMMZ 186653S; (k) Oncorhynchus tshaw- ytscha. UMMZ 212765S; (1) Oncorhynchus tshawytscha. UMMZ 178987S; (m) Oncorhynchus keta. UMMZ 175915S; (n) Oncorhynchus nerka. UMMZ 172454S; (o) Oncorhynchus gorbuscha. UMMZ 201722S. Abbreviations, ae : anterior extension; dba, broad anterior; ddp, strongly divergent posterior wings; dl, long dermethmoid; dp, divergent posterior wings; pn, posterior notched; pp, posterior pointed. 12 STEARLEY AND SMITH

sq ob sq

(a) (d) FIGURE 4. — Frontals, right, dorsal view, anterior up (parietals attached except in b). (a) Salmo trutta, UMMZ 175169S Oncorhynchus) ;(b clarki. UMMZ 181728S Oncorhynchus) ;(c mykiss, UMMZ 198677S Oncorhynchus) ;(d kisutch. UMMZ 187925S. Abbreviations: ob, anterolateral margin oblique; pa. parietal; sq, anterolateral margin squared.

chus mykiss can be variously aligned with each sphenoid) (transvers7 3 , f vomerino w ero e teeth other (Figure 12). present), and 81 (long ventral limb of preopercle) Several diagnosable nodes were discovered (Table 2). Some of these may be paedogenic char- (Figure 10) f particula.O r interese majoth e rar t acters. In the equally parsimonious solution, monophyletic groups substantiate y previoub d s Acantholingua ohridana joins Salmothymus.e Th work: the family Salmonidae (node 1 in Figure 10 consensus solution has a trichotomy at node 13. and Table 2), the subfamily Coregoninae (node 2), clade Th e abov archaie eth c trouts includes Hu- unnamee th d an d group (nod compose) e7 e th f do cho, Salvelinus. Salmo. Oncorhynchus.d an These subfamily Thymallinae plue subfamilth s y Sal- four genera for mmorphologicalla cladistid yan - moninae. Within the Salmoninae, the Eocene cally advanced clade here name Eusalmonine dth a Eosalmo is the sister group of all living salmo- (node 18)-the modern salmonines. Within the Eu- nines (node 9) as described by Wilson (1977). The salmonina, Hucho plus Salvelinus for mcladea , living Asian species, Brachymystax letiok.e th s i Salveline th i (node 19), whicsistee th s hri group sister of all other living salmonines (node 11) aclade sth f eo Salmo plus Oncorhynchus. Sale th - documented previously by Norden (1961). monini (node 22). Within the Salmonini, the At- Above the level of Brachymystax, some new lantic trout d salmon an sa monophyleti e ar s c relationship diagnosee sar characterr ou y db s (Fig- group, Salmo (node 23), and the Pacific trouts and ure 10). Three species of Mediterranean archaic salmons are a monophyletic group, Oncorhynchus irouls—Acantholingua ohridana. Salmothymus (node 24). Oncorhynchus unambiguously includes obtusirostris. d Platysalmoan platycephalus—are Pacifie th c trouts formerly classifie pars da t of Sal- next, sister groups of other salmonines (nodes 13- mo. Among the Pacific trouts, the rainbow trout 18 in Figure 10 and Table 2). Platysalmo platy- closs it d e relativean s (Behnke 1992: golden trout, cephalus Behnk sistee th shows ei e r b grou o nt p redband trout, and the fossil trout "Rhabdofario") of Salmothymus obtusirostris. Acantholingua oh- are closest to Pacific salmon; the Gila and Apache ridana severas ha l plesiomorphic states that pre- trouts (see Behnke 1992), cutthroat troutd an , vent it from joining the Salmothymus clade and, Mexican golden trou outside tar Pacifie eth c salm- in one of two equally parsimonious solutions, that on-rainbow trout group. Tabl list e2 monoe sth - exclude it from the Salmothymus plus Eusalmoni- phyletic groups supported by our data and details na clade: character (notches2 d dermethmoid), 15 all apomorphies (shown below node Figurn si e 10) (flat posterior frontal contact) 9 (flexe2 , d para- optimizes a PAUPy db wels , a autapomorphies la s SALMONID PHYLOGENY 13

pspd psp

psp

psp \pspd FIGURE 5.—Otic regio neurocraniumf no , left lateral view ) Thymallus(a , arcticus. UMMZ 172465S ) Brachy-;(b mystax lenok, UMMZ 172491S; (c) Acantholingua ohridana. UMMZ 177293S; (d) Salvelinus namaycush. UMMZ 172464S; (e) Oncorhynchus mykiss, UMMZ 198677S. Abbreviations: ehf, elongate hyomandibular fossa; i, inter- calar not contacting prootic; i-p, intercalar contacting prootic; p, prootic; psp, parasphenoid not deep posteriorly; pspd, parasphenoid deep posteriorly; shf. short hyomandibular fossa; sp, sphenotic without expanded anterior ramus; spr, sphenotic ra mexpandeds u ; la, trigeminofacial foramen anterior; tl, trigeminofacial foramen laterad lan expanded. 14 STEARLE SMITD YAN H

vc

FIGURE 6. — Vomer, Salvelinus larsoni, UMMP (Universit f Michigayo n Museu f Paleontologymo ) V69018) (a . ventral view, anterior up; (b) left lateral view. Abbreviations: It, longitudinal tooth row; tt, transverse tooth row; vc, vomerine crest supporting longitudinal tooth row.

(species-specific advanced traits, which were not Thymallus. Eosalmo is also the earliest known include mose searce th th r tn d i hfo parsimoniou s salmonine (Middle Eocene). Consilience between tree) that diagnose terminal branches. the stratigraphi cphylogenetie recorth d dan c tree is evidence that the phylogeny may be consistent Discussion with the history of the group. The goals of this study were to understand the The parsimony analysis presented above (Fig- phytogeny of the Salmoninae, especially the Pa- ure 10) strongly supports Norden' Berg'd san - spo cific trouts and salmons, the Salmonini. Some of sition tha archaie tth c trouts Brachymystax. Acan- the results are new and potentially controversial tholingua. and Salmothymus form a series of and require further discussion. cladistic intermediates between Thymallusd an more derived salmonines (Hucho. Salvelinus. Sal- Archaic Trouts . Oncorhynchus).mo Because Platysalmo platy- The classification of the archaic trouts and the cephalus Behnke 1968 is diagnosable as the sister resulting polarity of characters of morphologically specie Salmothymuso st obtusirostris, classis i t i - advanced salmonines is strengthened by the ad- fie dgenue herth n esi Salmothymus Berg 190s 8a ditiofossie th f ln o trout, Eosalmo, analysise th o t . Salmothymus platycephalus (Behnke). Prelimi- Eosalmo possesse syne st allth some-f no ,o t bu , nary observation n publisheo s d descriptionf o s apomorphies that have traditionally been used to Salmo ishchan of Armenia (Dorofeyeva 1978:fig- diagnose Salmoninae (noted by Wilson 1974). It ures I, 2, 3) indicate that it, too, and perhaps Sal- possesse slargea , fan-shaped proces stege th -n so mo carpio of Italy, belong to this clade. It is also ural, a complete arch and spine on preural cen- possible that Acantholingua ohridana should be hyomandibula d truan , m2 a situatede higth n ho classified in this clade, as suggested by Svetovidov neurocranium extann (Figuri s , noda t, 10 e 9) e equallo tw f o y e parsimoniou(1975on d an ) - sso Salmoninae. However, the frontals do not extend lution presene th n si t analysis charactee ;th r states posteriorl separato yt - ex parietalse e eth th d an , that hold it out of Salmothymus may be reductive trascapulars are broad (Figure 10, node 10), as in losse synapomorphif so c states. SALMONID PHYLOGENY 15

(C) qu

lap

Ce)

qu FIGURE 7.—Suspensoriu palatoquadrated man , left side, lateral view ) Thymallus(a , arcticus, UMMZ 186233S; (b) Brachymystax lenok. UMMZ 17249IS; (c) Huchoperryi. UMMZ 187613S; (d) Salvelinus namaycush, UMMZ 177542S; (e) Salmo trutta. UMMZ 183694S; (0 Oncorhynchus mykiss, UMMZ 198677S. Abbreviations: bh, anteriorly broadened hyomandibula; h, narrow hyomandibula; lap, long autopalatine crest; msp mpt overlao n , p of mesopterygoi metapterygoidd dan ; msp/mpt, mesopterygoid-metapterygoid overlap; mtp/pt, metapterygoid- pterygoid overlap obtus;qu, e quadrate angle; qua. acute quadrate angle; sap, short autopalatine crest symplectic;sy, ; sy/mpt, broad contact of symplectic and metapterygoid.

Salvelinus Salvethymusand 1978, 1980, 1984;Balon 1980, 1984; Kendald lan Behnke 1984; Cavende Kimurd ran a 1989; Phil- hypotheticae Th l arrangement of species of Sal- lip t alse . 1989; Grew t alee . 1990). Resolutiof no velinus in our study is not supported by other es- the conflicting estimates await studsa y that uses timate f relationshio s thin pi s genus (Cavender the total evidence. 16 STEARLE SMITD YAN H

(9)

FIGURE 8. —Preopercles, left lateral view, (a) Brachymystax lenok, UMMZ 172491; (b) Hucho perry i. UMMZ 187612S; (c) Salvelinus confluentis. UMMZ 189196S; (d) Salmo salar. UMMZ 209263S; (e) Oncorhynchus clarki, UMMZ 181728S 0 Oncorhynchus( ; tshawytscha. UMMZ 209844S ) Oncorhynchus(g ; nerka, UMMZ 182453S. Abbreviations: 11, lower lim f preoperclbo e intermediate; lie, lower limb elongate; llr, lower limb reduced, p ; preopercle without posterior extension , posteriope ; r extensio preoperclef no .

Salvethymus describes wa Chereshney db d van . svetovidoviS advancen a s i d species of Salvelinus Skopets (1990) from Lake El'gygytgyn in Siberia. relate malmao dt alpmus,d an indicates a e th y db The preponderance of reductive characters cited teeth, maxilla, vomer, metapterygoide th d an , diagnosie ith n f Salvethymusso svetovidovi sug- hyomandibular alternative Th . e interpretation— gests that eithe genue rth s derived from Salvelinus that it is an earlier branch, older than any of the by reductive evolutio s plesiomorphici t i r o n . species of Salvelinus—is indicated by the plesio- Chereshnev and Skopets (1990) favored the latter morphic (unreduced) basibranchia d glossoan l - explanation. Their descriptio f thino s distinctive hyal teeth. new species documents slow growth, small size, and several reductive characters—reductiof o n Vomerine Tooth Pattern predorsals, supraorbitals, orbitosphenoid, basi- The relationships of the archaic trouts described sphenoid, pelvic axillary processes, vomerine teeth, by the parsimony analysis (Figure 10) disagree with and breeding colors. These stan contrasn di s it o t those put forth by classification schemes relying specialized characters suc straighs ha t maxilla, large on vomerine tooth pattern (e.g., Kendald an l teeth, and increased gill raker number. Possibly Behnke 1984). Vladykov (1963) cautioned against SALMONID PHYLOGENY 17

(f)

FIGURE 9.—Ceratohyals, right lateral view, (a) Salvelinus namaycush. UMMZ 203837S; (b) Salmo trutta, UMMZ 172470S; (c) Oncorhynchus clarki. UMMZ 203892; (d) Oncorhynchus gilae. 182405S; (c) Oncorhynchus mykiss. 203835S ) Oncorhynchus(f ; kisutch, UMMZ 20543 IS. Examplefard elongatee ar an e, c e shor d , , bd ;sa an , t relativ deptho et . overly weighting this character. Five basic pat- long vomeral shaft. Hucho Brachymystaxd an e ar terns of vomerine tooth arrangement can be iden- unusua havinn i l gbroaa d transvers teetf o hw ero tified in extant salmonids. Thymallus possesses a o nlateralla y expanded anterio (headd a en r f o ) short vomer with a small, anterior patch of teeth. short vomer. Finally, Salvelinus species all possess extane Ith n t coregonine genera Prosopiumd an teeth in a patch on the head of the vomer, and in (most) Coregonus, teeth are also small and re- most Salvelinus species, this patc followes hi y db vomere stricte anterioth e f conth y o B o .dd t - ren a zig-zag column of teeth supported not by the trast, Salmo. Oncorhynchus. Salmothymus (in- shaft of the vomer but by a crest ventral to the cluding Platysalmo] all possess a long, often shaft and anchored to the head of the vomer. zig-zag longitudina substantiaf o w ro l l teeta n ho (Text resume pagn so e 22.)

FIGURE 10.—Cladogra relationshipmf o salmonif so d genera. Character suites supporting nodes 1-2 describee 4ar d in Table 2. The taxon known only as fossils is indicated by a dagger. 18 STEARLEY AND SMITH

FIGURE 11.—Consensus cladogram of relationships of Hucho and Salve/inns. Character suites supporting nodes 19-37 are described in Table 2. The taxon known only as fossils is indicated by a dagger.

0- 0- 0- 0- 0' 0- 0- 0- 0- 0- 0- 0- 0- 0-

FIGURE 12.—Consensus cladogram of relationships of Sal mo and Oncorhynchus. Character suites supporting nodes 22-65 are described in Table 2. The taxa known only as fossils are indicated by a dagger. SALMONID PHYLOGENY 19

TABLE 2.—Character suppor monophyletir tfo c groups TABLE 2.—Continued. discovere thin di s analysis. Character state e thossar e listed in Table I and illustrated in Figures 10-12. To Char- help assess the evidence for each node, suffixes are added acter Descriptio statd nan e characteo t r descriptions. Uniqu unreversed ean d char- 34 Toothed vomer ( 1 > 0) acter state followee sar asterisn a y db k (*). Unambiguous 74 Supraorbital contacts dermosphenotic (aut.) character state transitions (as opposed to states that could 92 Branchiostegals between 10 and 13(1) be parsimoniously optimized otherwise) are followed by "unam." Several characters undergo reversal varioun si s Node 7: Thymallus plus Salmoninae clades. Reversed characters are indicated by symbols 9 Ethmoid (hypethmoid) absent ( 1 ) (unam.) showing the transition: for example, "I>0." Reversals 34 Toothed vomer ( 1 > 0) e frequentlar y unambiguou s wella s . Autapomorphies 46 Well-toothed palatines ) (*( 1)>0 that wer t includee no compute e th n di r analysi- in e sar 49 Toothed maxillae ( I >0) (*) dicated by "aut." 57 Premaxilla with ascending process (!)(*) 63 Long, lanceolate supramaxilla (1) (unam.) Char- 65 Coronoid proces dentarf so y lower, risint ga acter Description and state angle of 45° or less (!)(*) 7 1 Posterior process of angulo-articular at angle Node 1: Salmonidae horizontao t l (!)(*) 20 Epiotics with posterior sulcus (!)(*) 108 Nuptial tubercles absent (I) (unam.) 5 2 Orbitosphenoid present (1) Nod Thymallinae: e8 , Thymallus 30 Parasphenoid extend posterioo st basiocf ro - cipital (!)(*) 25 Orbitosphenoid absent ( 1 >0) (*) 31 Posterior parasphenoid with high walls flank- 88 Basibranchial plate absent ( 1 ) ing myodome (1) 99 17 or more dorsal fin rays (1) (aut.) 33 Occipital condyle tripartite (0) 1 19 Sensory papillae surrounding nares ( 1 ) (aut.) 73 Supraorbital short (1) Node 9: Salmoninae 94 Caudal arches with peg-and-socket arrange- ment (Rosen 1974) (!)(*) 1 2 Frontals form anterior floo f posttemporao r l 97 Neural spine detached from arc preuran ho l fossae (1) (unam.) centrum 2(1) (unam.) 1 3 Frontals expanded above sphenotics (!)(*) 103 Tetraploid karyotype (!)(*) 1 9 Pterotic with long hyomandibula fossa (!)(*) 31 Posterior parasphenoid flacrosn i t s section 110 Parr marks present (1) (l>0)(unam.) Node 2: Coregoninae 37 Vomerine teet expanden hi d anterior trans- 4 Dermethmoid contacts but does not overlap verse row ( 1 ) frontals; frontals separate nasals (!)(*) 45 Mesopterygoid overlapping quadrate (!)(*) 55 Premaxillary teeth vestigial in adults (!)(*) 80 Suprapreopercle present (!)(*) 0 9 Broad, typically perforate ceratohyal (1) 85 Median basihyal denticles absent (1) 5 9 Urostyle ossifications ("tendon bones") pres- 86 Strong teeth on perimeter of basihyal (!)(*) ent (1>0)(*) 96 Large fan-shaped plat stcguran eo l (!)(*) 97 Complete arch and spine on preural centrum Node 3: Prosopium 2 (0) (unam.) 2 Dermethmoid without posterior notch (1 >2) (unam.) Nod Eosalmo: e10 3 Long dermethmoid (unam.) No unique characters betweep Ga 66n coronoi dentarf do angud yan - lar-articular (aut.) Node 11 2 Dermethmoid without posterior notch (1 >2) Nod : Coregonuse4 plus Stenodus 1 4 Frontals extend between parictals (!)(*) 33 Occipital condyle secondarily fused (2) 47 Palatine crest long ( 1 ) (unam.) 53 Premaxillary proces f maxillso a angled dor- 3 7 Long supraorbital) (1>0 sally (1) 88 Basibranchial plate absent (1) 76 Postorbitals do not cover hyomandibula nostrio Tw 10l 4flap s (!)(*) 105 Pyloric caecae mor (unam.) e tha(2 0 n7 ) 84 Extrascapulars tubular (!)(*) 110 Without parr marks (1 >0) 105 Pyloric caecae between 20 and 70 ( 1 ) Node 5: Coregonus 109 Egg size greate (!)(*m r m tha 5 ) n3. uniquo N e characters Nod Brachymystax: e12 Nod Stenodus: e6 3 Dermethmoid long (1) (unam.) 18 Sphenotic with stout anterior ramus (1) 102 Lateral line scales elliptica) (1 l (unam.) 105 Pyloric caecae more than 70 (1 >2) (unam.) 29 Parasphenoid with straight sagittal profile (1) Node 13 31 Posterior parasphenoid flat in cross section 35 Vomerine shaft bears teeth and extends pos- (unam.)(l>0) terio laterao rt l ethmoids (1) (unam.) 20 STEARLEY AND SMITH

TABLE 2.—Continued. TABLE 2.—Continued. Char- Char- acter Description and state acter Description and state 61 Premaxilla with cartilage pocket (1) (unam.) Node 22: Salmo plus Onchornynchus 3 8 Subopercle shallow (1 >0) 37 Anterior transvers vomeen o toot - w rre hro 92 Branchiostegals more than 10 (1) (unam.) duced (1>0) 98 Twoepurals(l) 39 Vomer with anterior extension in breeding Node 14: Acantholingua ohridanus males (!)(*) 51 Maxillae arched ) (unam. (1>2 ) 2 Dermethmoid with posterior notch (2> 1) Maxillae ovat rouno et crosn di s section (1) 36 Vomeral teeth extendin posteriormoso gt t 52 end of vomeral shaft (aut.) (*) 58 Ascending process of premaxilla posterolater- 75 Multiple supraorbitals (aut.) ally deflected (!)(*) 85 Median basihyal denticles present (1 >0) 67 Kyp dentarn eo y (1) Nod Salmothymus: e15 plus Platysalmo 9 Ethmoid presen t) (unam. (1>0 ) Nod Salmo: e23 15 Posterior midline depression in frontals (1) Dermethmoid broad, blunt, diamond-shaped (*) (!)(*) 29 Parasphenoid straight in sagittal profile 62 Mesial process present on premaxilla (!)(*) (0>1) 68 Extreme development of kype on dentary 37 Transvers f vomerino w ero e dentitio- nre (Morion 1965) (!)(*) duced (1>0) 83 Subopercle shallow) (1>0 Nod Salmothymus: e16 31 Posterior myodome with high wall 1> ) s(0 Node 24: Oncorhynchus 101 Gill rakers more than 25 (0> 1) (unam.) Dermethmoid with posterior notch (2> 1) 102 Lateral line scales elliptical (1) (unam.) 23 Intercalar contacts prooti (unam.) c(1 ) Nod Platysalmo: e17 47 Palatine crest shor t) (unam. (1>0 ) 105 Pyloric caecae fewer than 20 (1 >0) (unam.) 48 Margin quadratf so e form acute angle Nod Eusalmonin: e18 a (unam.) 53 Premaxillary proces f maxillso t dorsaano l 24 Prootic foramina displaced posteromedially (l>0)(unam.) (!)(*) Dentary deep anterior to Meckelian groove 26 Orbitosphenoid without anterior emargina- 64 (1) tion (1) (unam.) 72 Retroarticular suture at high angle (1) 42 Metapterygoid not in broad contact with 76 Postorbitals cover hyomandibula (1 >0) symplectic (!)(*) (unam.) 50 Maxilla extends posterior to orbit (!)(*) 78 Second infraorbital tubular (!)(*) 51 Maxilla straigh archedo t t , without convex 81 Lower lim f preoperclbo e greatly reduced ventral edge (!)(*) 65 Coronoid process of dentary shallow (1) (l>2)(unam.) 98 Three epurals (1>0) (unam.) 11 r orang2o d eRe cutthroat mark (1) 109 Egg size greater than 4.5 mm (1 >2) (*) 114 Dark borde f adipos ro (unam.) (1 n efi ) Node 19: Salvelinus plus Hue ho Nod Hue: e25 ho hucho 18 Sphenotic with stout anterior ramus (1) (unam.) 88 Basibranchial plate absent (10 (unam.) 5 3 Vomer shor t) (unam. (1>0 ) 89 Basibranchial teeth absent (1) 63 Supramaxilla long, inflected (1 >2) (*) 9 8 Basibranchial teeth present) (1>0 Nod : Huchoe26 perry! 93 Vertebral count greater than 60 (1) 9 Ethmoid presen t) (unam. (1>0 ) 102 Lateral line scales elliptical (1) 85 Median basihyal denticles present) (1>0 93 Vertebrae 60 or fewer (1 >0) Nod : Huee20 ho 98 Three epurals (1>0) 9 2 Parasphenoid straigh sagittan i t l profile (1) 64 Dentary deep anterior to Mackelian groove Node 27: Salvelinus larsoni (1) (unam.) 85 Median basihyal denticles present) (1>0 100 Gill raker count low, fewe) (* ) r tha(1 6 1 n 105 Pyloric caecae count high, more tha0 n7 Node 28: Extant Salvelinus (1>2) 37 Anterior vomeral transverse tooth row re- duced (1>0) Node 21: Salvelinus 67 Kype present on dentary (1) 27 Orbitosphenoid oval in cross section (!)(*) 77 Infraorbitals restricted to 5 (0> 1) (*) 38 Vomeral teeth on a raised crest (1 )(*) 111 White spot darn so k background (!)(*) SALMONID PHYLOGENY 21

TABLE 2.—Continued. TABLE 2.—Continued. Char- Char- acter Description and state acter Description and state

Nod9 e2 Node 42: Oncorhynchus clarki 41 Hyomandibula broad, "dish-shaped" sensu 89 Basibranchial teeth present (1 >0) Cavender 1980 (!)(*) 48 Margins of quadrate form acute angle (1) Nod3 e4 (unam.) 91 Ceratohyal square, stubby (1) (unam.) 115 Vermiculations present (1) Nod : Oncorhynchuse44 gilae Node 30 6 7 Postorbital t coverinsno g hyomandibula (1) 43 Metapterygoid extends dorsally almost to 113 Yellow cutthroat mark (!)(*) pterotic (!)(*) Node 45: Oncorhynchus gilae gilae 3 9 Vertebral number 6r greate1o r (1) uniquo N e characters Node 31: Salvelinus namaycush Nod : Oncorhynchuse46 gilae apache 105 Pyloric caecae more than 70 (1 >2) 108 Nuptial tubercles present (1 >0) (unam.) No unique characters Nod : Salvelinuse32 conftuentus Node 47 29 Parasphenoid straight in sagittal profile (1) 7 Dermethmoid "A-shaped" (!)(*) 51 Maxilla arche d(unam.) 2 ( 1> ) 10 Lateral ethmoids square (!)(*) 72 Retroarticular suture at high angle (1) 16 Frontals with expanded shelf above orbit (1) 115 Vermiculations absent (1 > 0) (*) Nod Salvelinus: e33 fontinalis Node 48: Oncorhynchus lacustris 81 Extreme reduction of lower limb of preoper- 21 Epiotics with large conical processes (1) (aut.) cle (1>2) (unam.) Node 49: Oncorhynchus mykiss aguabonita Nod Salvelinus: e34 leucomaenis plus "redband" 3 2 Intercalar contacts prootic (1) (unam.) 6 2 Orbitosphenoid with anterior emargination (l>0)(unam.) Node 35 5 Dermethmoid with prominent midlength Nod : Oncorhynchuse50 mykiss aguabonita constriction (!)(*) 91 Slender ceratohyal (1 >) 0 12 Frontal t forno m o sd par f flooo t f posto r - 117 Dorsal, anal d pelvian , c fins with white tips temporal fossae (1 >0) (unam.) (D(aut.) 72 Retroarticular suture at high angle (1) Node 51: Oncorhynchus mykiss gairdneri 93 Vertebral count high, 61 or greater (1) ("redband" trout, Oregon) Node 36: Salvelinus alpinus uniquo N e characters No unique characters Nod : Oncorhynchuse52 mykiss irideus (North Nod Salvelinus: e37 malma America) and O. m. mykiss (Asia) 37 Anterior transverse vomeral dentition pres- uniquo N e characters ent (0>1) 101 Gill raker count high, greater than 25 (1) Node 53: Subgenus Oncorhynchus (Pacific salmons) (unam.) 40 Vomeral teeth deciduous (1) (unam.) 54 Premaxillary process of maxilla palmate (1) Node 38: Salmo trutta (*) 2 9 Branchiostegals fewe) >0 r 1 ( tha 0 1 n 56 Premaxilla with enlarged breeding tusks (1) Nod Salmo: e39 salar (*) 40 Vomeral teeth deciduous (0> 1) (unam.) 61 Premaxillary cartilage pocket absent (1 >0) 116 X-shaped spots (aut.) (unam.) 63 Supramaxilla broadly ovate (1 >0) (unam.) Node 40: Oncorhynchus chrysogaster 64 Dentary not deep anterior to Meckelian 29 Parasphenoid straight in sagittal section (1) groove (1 >0) 72 Retroarticular eclipse d(unam.) 2 ( 1> ) 69 Dentary teeth deciduous (!)(*) 79 Postorbitals divided intserieo otw s (aut.) 72 Retroarticular suture high; retroarticular 92 Branchiostegals fewer than 10 (1 >0) eclipsed (unam.) (1>2 ) 82 Dorsal lim preoperclf bo e expanded posteri- Node 41 orly (!)(*) 31 Posterior myodome with high walls (1) 2 9 Branchiostegals more tha ) (unam.n >2 11 3( ) (unam.) 32 Basisphenoid process of parasphcnoid well Nod : Oncorhynchuse54 masou ossified (!)(*) 98 Twoepurals(l) 93 Vertebral count greater than 60 (1) 118 Anterior margin of caudal fin red (1) (aut.) 22 STEARLE SMITD YAN H

TABLE 2.—Continued. However, morphologically intermediate species that exhibit combinations of the above states exist Char- acter Description and state (or formerly existed). Acantholingua possesses a strong transvers anteriof o w ero r vomerine teeth, Node 55 as well as the longitudinal row of teeth on a long 1 Dorsal fontanelles close during ontogeny (1) shaft (i.e. "T-shapeda , " pattern) extince Th . t sal- (*) monine Salvelinus larsoni (Kimmel 1975) is re- 3 9 Vertebral count greate) r(* tha) 2 ( 5 1n> 6 105 Pyloric caecae mor) >2 e 1 tha( 0 n7 markabl possessioe th r efo strona f no g transverse 114 Dark borde f adiposro absenn efi t (1 ) >0 row of teeth on the head of the vomer as in Hucho, (unam.) but with a longitudinal column of teeth on a raised Nod : Oncorhynchuse56 kisutch crest behin vome e heae Salvelinusth n d th i f ds o ra 22 Supraoccipital crest extremely long (1) (aut.) (Figure 6). Node57 Thus, the parsimony analysis (Figures 10, 11, 7 Dermethmoid with widely divergent posteri- 12; Tabl ) yield2 e e followinth s g hypothetical or wings (1 > 2) (*) transformation serie vomerinf so e tooth patterns Node 58: Oncorhynchus tshawytscha within the Salmoninae. At node 7, the ancestral 28 Orbitosphenoid in form of spongey ball (1) stat transversa s ei e patc paia smalr f hro o l patch- (aut.) es of teeth on the anterior end of short vomer as in Thymallus. patce Th h becam etransversa e tooth Node 59: 'Type A" Pacific salmons (Hikita 1962) row on the head of a short vomer at node 9, as in 8 Dermethmoid with anterior constricted ex- tension (Vladykov 1962)(1) Bmchymystax. Extensio e vomerinth f no e shaft 51 Maxilla straigh 1> ) 2 (unam.( t ) additiod an longitudinaa f no e th lo t toot w hro 59 Thin cres premaxillf o t a (sensu Vladykov transverse toot formew hro "T-shapeda d " pat- 1962) (!)(*) ter t nodna e longitudina13e th ; furthes wa w r ro l 87 Pointed basihyal (0> 1) (*) extended in Acantholingua, node 14. The condi- Nod : Oncorhynchuse60 keta tio t nodna e 13 transformed three separate times 98 Twoepurals(l) at nodes 15, 21, and 22: reduction of the "T" to Node 61 an "I" patter transverse th losy nf b so e row- ,re 17 Frontals contact epiotics in large individuals tentio vomerine f teetth no n ho e shaft (indepen- (DC) dently acquired in two clades, Salmothymus ob- 101 Gill raker count high, greater than 25 (1) (unam.) tusirostris plus platycephalus [node 15] and Salmo 106 Dorsal hump in breeding males (condition in plus Oncorhynchus [node 22]), and elevation of O. rastrosus unknown) the "T" pattern onto transverse and longitudinal Nod : Oncorhynchuse62 gorbuscha crest t noda s e 21s seea , Salvelinusn i n larsoni 72 Retroarticular suture hig t retroarticulahbu r (Figure 6). This left the plesiomorphic presence of not eclipsed (2>1) transversa vome e heae teetth f th f o do n rhw o ero 107 Extreme development of dorsal hump (1) in Hucho (node 20) longitudinao , whicn s ha h l (aut.) row. Reductio "Te th " f npattero elevaten a o nt d Nod : Oncorhynchuse63 nerka plu . rastrosussO "I" pattervomerine th n no e crest (variabley b , ) 81 Ventral lim f preoperclbo e only moderately loss of the transverse row on the head of the vo- reduced (2>\) (unam.) mer, occurre extann di t species of Salvelinus (node Nod : Oncorhynchuse64 nerka 28). This transformation series of vomerine states 0 7 Dark enameloi interion do teetf ro h (Vlady- emerge mose th n tsi parsimonious trees resulting kov 1962) (1) (aut.) from the cladistic analysis. Nod : Oncorhynchuse65 rastrosus 8 Dermethmoid without anterior constricted Characters Uniting Salmo Oncorhynchusand extension (1>0) 33 Occipital condyle simple (0> 1) (unam.) Several characters are common to Pacific and 0 6 Dark ename premaxillarn o l y tusk (1) (aut.) Atlantic salmon troutd san s (Figure , 12s10 ; node 64 Dentary deep anterior to Meckelian groove 22, Table 2). The diagnostic characters are the (1) more elongate vomer wit hreducea d transverse 5 6 Coronid proces dentarf so y only moderately toot (charactew hro r 37), which becomes extended low, approximatel (2° (unam.) y>45 1 ) anteriorly in breeding males (character 39); a long maxilla that is arched (character 51, individuals of larger size generally exhibiting greater arch) and SALMONID PHYLOGENY 23

ovat crosn ei s section (characte definitive th ; r52 e Several morphological features are common to round maxillary shaft of Rhabdofario eventually only more somth f eeo derived Pacific troutd san appears in about 1 -m-long specimens of this clade to Pacific salmons. All Pacific trouts and salmons, allometrin a s a c terminal addition arce th s h i t bu , except the Mexican golden trout (Oncorhynchus later lost in Oncorhynchus nerka, keta, and gor- chrysogaster Needham and Gard 1964), possess a buscha at node 53); a long premaxilla with pos- deep posterior parasphenoid with an accompa- teriorly deflected ascending processes (character nying ossified basisphenoid proces parae th f -so 58; the ascending processes are associated with the sphenoid. The keel on the parasphenoid at its flex- rostral cartilage and typically become arched in ure, note Cavendey db Milled ran r (1982 Pacifin )i c breeding males); and a dentary with a well-devel- salmons, is presen largn o t e specimen f Pacifiso c oped kyp breedinn ei g males (character 67, doc- trout as well. All Pacific trouts and salmons, ex- umente Morioy db n 1965). Although characte, r39 cept O. chrysogaster and O. clarki, possess rect- the anterior extension of the vomer, was used by angular ceratohyals. Three features "A"-shapen a , d Cavende Milled ran r (1982 diagnoso )t clade eth e dermethmoid, frontals wit widha e anterior shelf f Pacifio c trout d salmonsan s only, examination expanded ove orbitse th rwidd an , e lateral eth- of more specimens leads to agreement with Tcher- moids, are possessed by the rainbow, red band, navin (1938b) that all trouts and salmons possess and California golden trouts and Pacific salmons. this featur somo et e extent t appeari o s , t nodsa e Several fossil forms—Oncorhynchus "Rhabdo- 22. Strong kype alse sar o foun Salvelinusn di mal- fario" lacustris fro Miocene mth Pliocend ean f eo ma: weakly developed kypes are found in Salveli- Idaho and Oregon (Kimmel 1975; Smith 1975; fonts nu inalis Salvelinusd an confluentus (Morton Smith et al. 1982), and Oncorhynchus australis 1965; R. J. Behnke, Colorado State University, (Cavender and Miller 1982) of the Pleistocene of personal communication). Mexico—ar mykiss. e O relate e th o lineagedt , based Synapomorphies of Pacific trouts and salm- on the shape of their frontals, jaw bones, cerato- ons.—Thirteen morphological features unit- Pa e hyals dermethmoidsd an , e lineagTh . f Onco-eo cific trout d Pacifisan c salmons (Figured an 0 1 s rhynchus clarki representes i d from Miocend ean 12, node 24) mose .Th t diagnostic charactere sar Pliocene specimens fro Greae mth t Basi "Sal-s na the following: prominent posterior notch in the mo cyniclope" from the Miocene of Nevada dermethmoid (character 2); intercalar contacting (LaRivers 1964), "Rhabdofario"' sp. from Plio- prootic (23); shorter palatine crest (47); anterior cene sediment t Honesa y Lake, California (Taylor and posterior borders of the quadrate forming an and Smith 1981) "Salmod an , sp/' fro Plioe mth - acute angle (48); premaxillary proces maxe th f s-o cene Mopung Hills localit Nevadn yi a (Taylod ran illa not angled strongly dorsad (53); longer postor- Smith 1981). These records imply that specief so bitals (76); tubular second infraorbital (78)d ;an Pacific trout originate Miocenee th n di , probably three epural keta. masou. O s (O d exceptedan ; 98). before 6 million years ago (see also Behnke 1992). The prominent posterior notch in the supraeth- More tha millio6 n n year f historo s r somfo y e moi s firsdwa t note y Regab d n (1914) whee h n modern lineages of Pacific salmons is further sup- suggested placing Pacific salmon Pacifid san c trouts ported by Oncorhynchus "Smilodonichthys" ras- in one genus. The long postorbitals and number trosus fro Miocene mth Californif eo Oregod aan n epuralf o s were note Vladykoy db v (1963). These (Cavender and Miller 1972; Barnes et al. 1985); features contace wels th a ,s a l t betwee intere nth - an interior form of "Smilodonichthys," Onco- cala prooticd ran , were cite Sanfory db d (1990n )i rhynchus sp., fro Miocene mth f Idaheo o (Smith an independent suggestion to place the Pacific et al. 1982); Oncorhynchus salax. a sister species salmon troutd san Oncorhynchus.n si Characters of O. nerka from the Miocene of Idaho and Or- 2, 47, 53, 76, and 78 were figured by Smith and egon (Smith 1975; Smit . 1982)al t Onco-d he an ; Stearley (1989 supporn i )e relationshi th f o t f po Pacific trout d salmonsan s n Norden'I . s (1961) rhynchus keta from the Miocene of Oregon and detailed discussio e chondrocraniumth f o n e h , Idaho (Smith 1992). In contrast to the frequently noted thaazygoue th t s rostrum (Figure 2d), said cited conclusion (Clemens 1953; Neave 1958) that diagnostie b o t f Oncorhynchusco Tchernaviy b n salmon species evolve Pleistocenee th n di ever o n (1937) and Kendall and Behnke (1984), was sec- in the past 1 million years, these fossils of Onco- ondary, typica f Pacifio l c salmon coming into rhynchus document abundant evidenc mina r efo - breeding condition e fine presenb W d. o it tn i t millio6 f imuo e nmmodere ag year th r sfo n spe- large, migratory O. mykiss (steelhead), as well. cie f Pacifiso c trou salmod an t n (Smith 1992). 24 STEARLEY AND SMITH

Molecular and Biochemical Evidence my outgroupe kiss th s i successive ,th e branchef so the tree are coho, chinook, sockeye, chum, and Berg and Ferns (1984) studied the amount of pink salmon. divergence of mitochondrial DNA (mtDNA) majoo Tw r unsolved problems remai On-n ni among four species: brook trout, brown trout, corhynchus after this analysis of molecular data rainbow trout, and Chinook salmon. Their discov- sets. The first is the placement of the cutthroat ery that rainbow trou chinood an t k salmod nha trout secone ;th resolutios di relationshipe th f no s diverged from each other less than either had di- of pink, chum, and sockeye salmon. The cutthroat verged from brown trou broor o t k trout provided trout has always been regarded as the sister group support for close genealogical relationship be- rainbowe ofth , Gila, Apache, golden redband ,an d tween rainbow trou Pacifid an t c salmon- be t no , trouts (Behnke 1992). Cladistic analysi date th af so tween rainbow trout and brown trout (see also presentet se thin di s paper supports that view, with Grewe et al. 1990). The convincing cladistic evi- a crucial qualification e cutthroath : t trou- de t denc Bern ei Ferrisd gan ' (1984e th )s i dat t ase scended from a basal lineage (node 41) near the similarity of two mtDNA fragments created by the Mexican golden trout: that is, from the ancestor endonuclease Xbal foud an r fragments createy db to all other Pacific trout and salmons (Figure 12). HINdlll that are unique to rainbow trout and chi- It was not anticipated that the Pacific salmons, nook browt foune salmoth no n d i n ntrouan r o t not the cutthroat trout, are the closest sister group the outgroup brook trout. It is probable that at of the rainbow trout (Figure 12, node 47). least uniqusome th f eo e fragments were produced Evidence for our phylogeny lies in the discovery by homologous, derived restriction site thad san t tha tmorphologicao thern e ear l synapomorphies they offer good cladistic evidence. linking cutthroat trout to rainbow trout separate The study of mtDNA of Pacific salmon by Tho- fro othee mth r trout salmonsd othee san th n r O . . (1986maal t se ) provided valuable - mapre f so hand, Wilson et al. (1985), in their study of rela- striction sites for rainbow trout and five species tionships among steelhead, rainbow troutd an , Pacifif o c salmon. Their data, which they analyzed cutthroat trout, had shown three restriction sites— as phenetic distances, indicate genetic similarity EcoR I (3rd site), Bgl II (3rd site), and Kpn I (3rd between rainbow troud coh d chinooan t an o k site)—linking cutthroat trou o rainbot t w trout salmo somd nan e genetic distanc thesf eo e species populations (Wilson et al. 1985: table 1). Fur- from chum, pink sockeyd ,an e salmon (Figure 13a; thermore, Gyllensten and Wilson (1987) showed see also Grewe et al. 1990). Without inclusion of 19 mtDNA fragments, cut by 10 restriction en- an outgroup, however distancee th , s provido en zymes, unique to rainbow and cutthroat trout. evidence of cladistic relationships and, in fact, give However, none of these sites or fragments can be a misleading impression of relationships. We have demonstrate a synapomorph y b o dt r clarkiyfo reanalyzed this data set cladistically, after desig- plus mykiss. The three sites shown by Wilson et nating the rainbow trout as the outgroup and thus al. (1985) all appear to be shared by Pacific salm- specifying its characters as primitive for the spe- on, as shown by Thomas et al. (1986: figure 3), cies include thin di s study base choice W .e th f eo and therefore provide no evidence for a separate outgrou conclusione th n po Behnkf so e (1968d )an sister group relationship for rainbow and cut- r cladistiou c analysi f morphologicao s l datan o , throat trout. Comparison of the fragment lengths the protein evidence of Tsuyuki and Roberts (1966) shown by Gyllensten and Wilson (1987: appendix and Utter et al. (1973), and on the molecular ev- 12.1) with the sites mapped by Thomas et al. (1986) idence that rainbow trout have diverged less than eighe foth r t enzyme common si n between these Pacific salmon from brown trout and brook trout two studies reveals that of the 13 fragments com- (Berg and Ferris 1984; Grewe et al. 1990). The mon to rainbow and cutthroat trout, only one restriction site data of Thomas et al. (1986) are (Pst I, 10.5 kilobases long) may involve a unique coded as discrete characters in Table 3 and ar- synapomorphy othere th ; commoe sar mano nt y range shoo dt direction e wth derivef so d character Pacific salmon and are therefore not evidence for state transitions from the states shown by Onco- separate shared ancestr. . mykissO O d r fo yan rhynchus mykiss—the best indication of the prim- clarki. t remainI cladisti a see e y b n(b o s t c study itive state for each character. The diagnoses of moleculaf o r evidence) whethe othee rth frag x rsi - group apparene s ar left-to-righe th n i t t character ments are evidence of plesiomorphic or synapo- state transition Tabln si resultine 3.Th g cladistic morphic sites conclusionn I . , ther almoss ei o n t estimate is shown in Figure 13b. If Oncorhynchus mtDNA evidenc r sharefo e d ancestry between SALMONID PHYLOGENY 25

(a) T FIGURE 13.—Compariso ) phenogra(a f ) cladograno (b d man m of mitochondria (mtDNAA DN ! ) data (from Thomas et al. 1986) bearing on the relationships of certain species of Oncorhynchus for which mtDNA data are available phenograe .Th m developed with the unweighted pair-group method with arithmetic average estimate) s(a s genetic similarity without respec branchino t g orde timen ri cladograe Th . estimate) m(b s branching orde timn ri e and phylogenetic relationships, assuming Oncorhynchus mykiss to be the outgroup for the other taxa (Pacific salmon).

rainbow and cutthroat trout, separate from Pacific the shared mtDNA characters might have been salmons. transferre blocka s da , countabl cladistie on s ea c moleculae Th biochemicad ran l data contribute ste matteo p n man w ho r y sit r fragmeneo t char- remarkabla o t e contras evidence th - re n i tr efo acter presene sar t (Smith 1992). Ferri (1983. al t se ) lationships among chum, pink sockeyd ,an e salm- studa In mor yof on. e than 19 gene loci, Utteret al. (1973) found pink and sockeye salmon to be TABLE 3.—Specie f Pacifio s c salmon Oncorhynchus spp. and their nearest relative (O. mykiss) arranged to similar (inde similarityf xo , 0.71), contrasting with show the sequential acquisition (from left to right) of chum salmon similarities of 0.47 and 0.54 with derived mitochondrial DNA restriction sites (1 +) and pind sockeykan e salmon, respectively. Tsuyuki los primitivf so e sites . (Primitiv1-) e state codee sar d Robertd an s (1966) also found protein evidence 0. Mitochondrial DNA data are from Thomas et al. fo relationshia r p between pin sockeyd kan e salm- (1986). Oncorhynchus gorbuscha shares four unique sites . Cladistion c reanalysi date Uttef th . ao f al s o t re wit keta.. honl t O unique bu y on e site, P64, wit sistes hit r species . nerka.O , discrets a e character states shows four protein syn- apomorphies shared by pink and sockeye salmon, O. o. O. compared to no clear support for other pairs. Our mykiss O. tshawyt- 0. gor- 0. Restric- rain- kisuich scha nerka buscha keta morphological data, especially characters involv- tion bow coho chinook sockeye pink chum ingile glth raker teethd san , agree wit proteie hth n site trout salmon salmon salmon salmon salmon dat indicatinn ai g that gorbuscha sistee th s ri spe- S10 0 0 0 0 1- 1- cie f nerka.so HI 50 0 0 0 0 1 + 1 + But pink salmo similae nar chuo rt m salmon i X46 0 0 0 0 1- 1- their mtDNA, showing sequence divergencf o e H87 0 0 0 0 1- 1- only 2.7% (compared to 4.6% and 5.2% sequence K10 0 0 0 1 + 1 + 1+ B78 0 0 0 - 1- 1- divergence between pink and sockeye salmon and P58 0 0 0 - 1- 1- chum and sockeye salmon, respectively). Cladistic HI40 0 0 0 + 1 + 1 + analysi mtDNe th f so A data shows four synapo- BII42 0 0 0 - 1- 1 _ P64 0 0 0 - l- 0 morphies shared by pink and chum salmon, com- X50 0 0 0 - 0 1- pared to no clear support for other combinations BII95 0 0 1 + 1+ l-f 1+ (Table 3). The mtDNA data are consistent with BI26 0 0 1- 0 1- 1- interpretations based on life history (Hoar 1958). HI33 0 1 + 1 + 0 1+ 1 + However, becaus lace recombinationf th k o f eo , X64 0 1- 0 0 1- 1- the several mtDNA characters are not indepen- K81 0 1- l- 0 0 _ I dent evidence; if introgression has occurred, all of K91 0 1- 1- 0 0 0 26 STEARLEY AND SMITH

demonstrated introgressive transfe f mtDNo r A Advanced salmonines form two lineages: (1) the through populations of European species of mice. clade of chars, Salvelinus. huchend an , Hucho; and Smith (1992) documented evidence of introgres- (2) the clade of Atlantic and Pacific salmons and sive transfe f charactero r fishesn si . trouts. Sal mo and Oncorhynchus. The Pacific conflice Th t betwee biochemicae nth l evidence a monophyleti t troutno e ar s c grou t rathebu p r for relationship between nerka and gorbuscha ver- represent several ancient branches f whico e hon , e moleculath s su r evidenc r relationshifo e - pbe produced Pacific salmons. Oncorhynchus mykiss. tween teste e nerkab compariketay d y db an ma - the rainbow trout, California golden trout, and sons with independent data setse karyotypTh . e redband a naturatrout n i s i ,l group with Pacific evidenc importantn a s ei , independent sourcf eo salmons. Cutthroat trou thd ean t Mexican golden information. The 2N chromosome numbers are trou outside tar Pacifie eth c salmon—rainbow trout 7keta n 4metacentrii 6 (2 acrocentric)8 4 d can 6 5 , group. Recognition of Pacific trouts as a clade in nerka (44 metacentric and 12 acrocentric). 52 "Parasatmo" t supporteno s i d because that name in gorbuscha metacentri8 (4 acrocentric)4 d can , is applicabl ecutthroae onlth o yt t trout t cannoI . t metacentri2 (3 8 acrocentric6 6 3 d d an can e th n )i be broadened to include rainbow trouts because outgroup species, tshawytscha (Simon 1963; R. B. Rhabdofario is a prior name for that group. Pacific Phillips, Universit f Wisconsino y . Milwaukee, a natura t troutno le grouar s p because thee yar personal communication) parsimonA . y analysis paraphyleti tha n taxoce i th t formeo ns d doet sno of fission and fusion steps among metacentrics and include all of its descendants. acrocentric above th f eso four taxa indicates that The terms "trout" and "salmon" do not refer step2 2 fusions6 6 fission( s1 d an s) would yield naturao t l phylogenetic groups. These names orig- numbers require consistene b o t d t wit e treth he inally referre lifo dt e history attributes: trout usu- based on the protein data; at least 34 steps (18 ally complete their life cycle in freshwater streams fission d 16san fusions) woul necessare db e b o yt and lakes, while salmon usually migrate to sea congruent wit tree hth e mtDN e baseth n do A data. (accordin o Englist g h n Nineteenti usage t bu , h Thus the chromosome data are congruent with the Century French, the appellations signified the op- protei morphologicad nan l dat indicatinn ai g that posite; see Dumeril 1856). Interesting exceptions nerka and gorbuscha are sister species, and that to common English usage include member trouf so t the ancestor of those two was the sister species to species that migrat sea—"salmoe th o et n trouts" keta. (sea-run S. trutta), coastal O. clarki, and steelhead This reanalysis lead threo st e important conclu- (O. mykiss)—and members of salmon species that sions. (1) Oncorhynchus gorbuscha is more closely arc lake-locked (kokanee, sebago, ouananiche, etc). relate . nerkaO o dt . keta. tha O Mitochon) o n(2 t - The common names based on these life history drial DNA estimates of historical relationship are attributes need not match phyletic groupings. Both ofte erron i n r becaus e dat e analyzeth e aar s a d the Atlantic clade, Pacifie Salmo.th d c an clade , phenetic distances, not in cladistic branching or- Oncorhynchus. include trouts as well as salmons. der. (3) Estimates of relationships are sometimes The Pacific salmon clade is a well-defined, cladis- in error because evolutionary histor bees yha n lost tically advanced, monophyletic subgroux si f po through introgression. Introgressive loss of evo- species, mos whosf o t e member aftee sdi r spawn- lutionary history may also lead to flawed esti- ing. These six species (Figure 12) of the genus On- matio f rateno f evolutionso exampln a ; seris ei - corhynchus can be diagnosed and recognized as ously overestimated rate f evolutioso f Pacifino c the subgenus Oncorhynchus. Some modern spe- salmon (Smith 1992). subgenue th cie n i s s Oncorhynchus hav ea fossi l record that goe slate bacth e o Miocenekt . Summary The phylogenetic analysis demonstrates that the Acknowledgments extant "archaic trouts" Brachymystax, Acantho- Alice Gosline translated Dorofeyeva papers from lingua. and Sahnothymus (including Platysalmo) Russia . o EnglisBonnint us r fo he Miljour drew are cladistically intermediate between graylings, Figures 2-13. Doug Begle, Paulo Buckup, Bill Fink, Thymallus. and the advanced salmonines Hucho, and the fishbone club were good influences. Reeve Salvelinus. Oncorhynchus.d an Sal. mo Eosalmo. Baile Roberd yan t Miller read manue partth f so - the oldest fossil salmonine, is confirmed to be the scrip provided an t d advic nomenclaturn eo d ean most archaic trout—the sister groul otheal f pro literature. Carl Bond, Robert Behnke, Barry Cher- salmonines. as documented by Wilson (1977). noflTd Petean , r Reinthal provided crucial speci- SALMONID PHYLOGENY 27

mens. Carl Bond also supplied helpful osteological Cavender, T. M. 1978. Taxonomy and distribution of information. Doug Nelson provided collectio- nor bule th l trout, Salvelinus confluentus (Suckley), from ganizatio d managementan n . Bill Fink, Arnold the American northwest. California FisGamd han e 64:139-174. Kluge, Doug Begle Carrb Bo , , Mark Wilsonn Do , Cavender, T. M. 1980. Systematics of Salvelinus from Peacor n FisherDa , , Phil Gingerich, Catherine the North Pacific Basin. Pages 295-322 in E. K. Badgley d Chrian , s Sanford contributed helpful Balon, editor. Chairs: salmonid fishes of the genus discussions. Ruth Phillips provided discussions, Salvelinus. . Junk e HagueW . Th ,Nethere Dr Th . - chromosome data referencesd an , . lands. Cavender, T. M, 1984. Cytotaxonomy of North Amer- ican Salvelinus. Pages 431-445 in L. Johnson and References B. L. Burns, editors. Biology of the arctic charr. Balon, E. K., editor. 1980. Chairs: salmonid fishes of University of Manitoba Press, Winnipeg. the genus Salvelinus. Dr. W. Junk, The Hague, The Cavender, T. M., and S. Kimura. 1989. Cytotaxonomy Netherlands. d interrelationshipan f Pacifio s c basin Salvelinus. Balon, E. K. 1984. Life histories of arctic chairs: an Physiolog Ecologd yan y Japan, Special Volume 1:49- epigenetic explanation of their invading ability and 68. evolution. Pages 109-14 . Johnso . L L B .n 1 i d nan Cavender, T. M., and R. R. Miller. 1972. Smilodonich- Burns, editors. Biology of the arctic charr. Univer- thys rastrosus—a new Pliocene salmonid fish from sit f Manitobyo a Press, Winnipeg. western United States. Universit f Oregonyo - Mu , Barnes . Raschke. McLeodE A G.. . . L ,R S , d .,an 1985. seum of Natural History, Bulletin 18, Eugene. A Late Miocene marine vertebrate assemblage from Cavender . MillerR . R . M. d T , 1982an , . Salmo aus- southern California. 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Part North American Salmonidae fro north-wese mth t fishe Th . . Richar3 d Bently, London. coast of America. Annals of the Lyceum of Natural Rosen . E 1974 . D , . Phylogen zoogeographd yan f yo History (New York) 7:306-313. salmoniform fishe relationshipd an s f Lepidoga-so Suckley Nort e . th 1874G , n h O America. n specief so laxias salamandroides. Bulletin of the American salmo troutd nan . Pages 91-16 Reporn 0e i th f o t Museu Naturaf mo l History 153:267-325. Commissioner for 1872-1873, part 2. U.S. Com- Rosen, D. E. 1985. An essay on Euteleostean classifi- missio Fisf Fisheriesnd o han , Washington, D.C. cation. American Museum Novitates 2827:1-57. Svetovidov, A. 1936. Graylings, genus Thymallus Cu- Rounsefell, G. A. 1962. Relationships among North vier, of Europe and Asia. Papers of the Zoological American Salmonidae. U.S. Fish and Wildlife Ser- Institute, USSR Academy of Sciences 3:183-301. vice Fishery Bulletin 62:235-270. (St. Petersburg.) Sanford . 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seu f Paleontologymo , Universit f Michigayo : n25 their broad geographical distribution. Transactions 339-413. of the Royal Society of Canada 1 (series 4, section Tchernavin . V 1937, . Skull f salmoo s d troutan n . 3):459-504. Salmo d Trouan n t Magazine 88:235-242. (Fish- Vladykov, V., and C. G. Gruchy. 1972. Comments on mongers' Hall, London.) the nomenclature of some subgenera of Salmoni- Tchernavin, V. 1938a. Notes on the chondrocranium dae. Journal of the Fisheries Research Board of branchiad an l skeleton of Sal. Proceedingmo e th f so Canada 29:1631-1632. Zoological Societ Londof yo 108:347-364nB . Walbaum, J. J. 1792. Petri Artedi renovati: bibliotheca Tchernavin . 1938bV , . Change salmoe th n si n skull. et philosophia ichlhyologica. Ichthyologiae, pars III. Philosophical Transactions of the Royal Society of A. RoeseF . , Grypeswaldiae. London 24 (part 2): 103-173. Weitzman, S. H. 1967. The origin of the stomiatoid . Beckenbach T . Withler . E A . ThomasR d , an , K. . . W , fishes with comments on the classification of sal- 1986. Mitochondria! DNA analysi f Pacifiso c sal- moniform fishes. Copeia 1967:507-540. monid evolution. Canadian Journal of Zoology 64: Wilson . Beckenbach. ThomasT K . . M.. A G , W ,d an , . 1058-1064. 1985. Intra interspecifid -an c mitochondriaA !DN . RobertsE Tsuyukid an , . H. ,1966 . Inter-specie- sre sequence divergence in Salmo: rainbow, steelhead, lationships within the genus Oncorhynchus based and cutthroat trout. Canadian Journal of Zoology on biochemical systematics. Journal of the Fisheries 63:2088-2094. Research Board of Canada 23:101-107. . 1974WilsonH . V . FossiM , l Tertiare fisheth f so f yo Allendorf . . HodginsO W . . F H Utter, d M. .,an . 1973,F . British Columbia. Doctoral dissertation. University Genetic variabilit d relationshipan y n Pacifii s c of Toronto, Toronto. salmo related nan d trout base protein do n variation. Wilson, M. V. H. 1977. Middle Eocene freshwater fish- Systematic Zoology 22:257-270. fros e m British Columbia. Royal Ontario Museum, Uyeno , MillerR . R ,. d T.1963an , . Summar f latyo e Life Sciences Contributions 113:1-61. Cenozoic freshwater fish record r Nortsfo h Ameri- Wilson, M. V. H., and P. Veilleux. 1982. Comparative . Occasionaca l PaperMuseue th f so f Zoologymo . osteolog d relationshipyan e Umbridath f so e (Pi- Universit Michigaf yo n 631:1-34. sces: Salmoniformes). Zoological Journal of the Vladykov . V 1962, . Osteological studie n Pacifio s c Linnean Society 76:321-352. salmo genue th f sno Oncorhynchus. Fisherie- Re s Received May 12, 1992 search Boar Canadf do a Bulletin 136:1-172. Accepted November 12. 1992 Vladykov. V. 1963. A review of salmonid genera and SALMONID PHYLOGENY 31

Appendix: Data Matri Salmonir xfo d Character States TABLE A. 1.—Numerical character state codes assigned to 119 salmonid characters as described in Table 1. Primitive state code e , derives0 ar s d a . Missin 2 d r stateo 1 r unavailablg o s sa e dat representee aar "?.y db "

Character Taxon 1-5 6-10 11-15 16-20 21-25 26-30 31-35 36-40 Novutnbra 00000 00010 11000 00000 00000 77000 00100 00000 Thaleichthys 00010 00000 10000 00000 00000 77000 00100 01000 Chanos 01000 00000 00000 00000 01000 77000 00110 00000 Proxopium 02100 00000 10000 00001 00001 00001 10010 00000 Coregonus 01010 00000 10000 00001 00001 00001 10110 00000 Stenodus 01010 00000 10000 00101 00001 ooon 00100 00000 Thymallus 01000 00010 10000 00001 00000 77001 10000 00000 Eosaimo 71000 00077 17700 00011 00071 77001 00000 •>•>•>•>•> Brachymystax 02100 00010 lino 00011 00001 00001 00000 01000 Acantholingua 01000 00010 11110 ooon 00001 00001 0000 1 11000 Salmothynuis 02000 00000 Mill 00011 00001 ooon 10001 00000 Platysalmo 02000 00000 11111 ooon 00001 ooon 00001 00000 Hucho hucho 02000 00010 lino 00111 ooon 10011 00000 01000 Hucho perry i 02000 00000 lino 00111 ooon 10011 00000 01000 Salvelinus larsoni 72000 00010 nno 00111 ooon 11001 00000 onoo ma 1 ma 02001 00010 10110 00111 ooon nooi 00000 01100 alpinus 02001 00010 10110 00111 ooon 11001 00000 00100 namaycush 02100 00010 nno 00111 ooon 11001 00000 00100 fontinalis 02100 00010 nno 00111 ooon 11001 00000 00100 confluentis 02100 00010 nno 00111 ooon non 00000 00100 leucomaenis 02000 00010 nno 00111 00111 11001 00000 00100 Salmo trutia 02000 10010 nno ooon ooon 10001 00001 00010 Salmo salar 02000 10010 nno ooon ooon 10001 00001 ooon Oncorhynchus chrysogaster 01000 00010 nno ooon 00111 10011 00001 00010 clarki 01000 00010 nno ooon 00111 10001 11001 00010 gilae 01000 00010 nno ooon 00111 10001 11001 00010 apache 01000 00010 nno ooon 00111 10001 11001 00010 lacustris 71000 01011 nno 10011 10111 10001 11001 00010 mykiss 01000 01011 nno 10011 00111 10001 11001 00010 aguabonita 01000 01011 nno 1001 1 00111 00001 11001 00010 (rcdband) 01000 01011 nno loon 00111 00001 11001 00010 mason 01000 01011 nno 10011 00111 10001 11001 10011 kisutch 11000 01011 nno 10011 01111 10001 11001 10011 tshawytscha 11000 02011 nno 10011 00111 10101 11001 10011 rastrosus 71000 02071 nno non 0011? 77701 11171 ooon keta 11000 02111 nno 10011 00111 10001 11001 ooon nerka 11000 02111 nno non 001 n 10001 11001 ooon gorbnscha 11000 02111 nno non 00111 10001 11001 ooon 32 STEARLEY AND SMITH

TABLE A. 1.—Extended. Character Taxon 41-45 46-50 51-55 56-60 61-65 66-70 71-75 76-80 Novumbra 0000! 01010 10000 00000 00001 00000 01??0 1???0 Thaleichthys 00000 01000 00000 00000 00002 00000 00000 10100 Chanos 00010 10010 0010? ?0000 00?00 000?? 00000 01001 Prosopium 00010 10010 00001 00000 00000 10000 00100 00000 Coregonus 00010 10010 0000 1 00000 00000 00000 00000 00000 Stenodus 00010 10010 00001 00000 00000 00000 00010 00000 Thymallus 00010 00000 00000 01000 00101 00000 10100 00000 Eosalmo 0001? 00000 00000 01000 00101 0000? 1?100 0000? Brachymystax 00011 01000 00100 01000 00101 00000 10100 10001 Acantholingua 00011 01000 00100 01000 10101 00000 10101 10001 Salmothymus 00011 01000 00100 01000 10101 00000 10100 10001 Platysalmo 00011 01000 00100 01000 10101 00000 10100 10001 Hucho hucho 01011 01001 10100 01000 10212 00000 10100 10001 Hucho perryi 01011 01001 10100 01000 10212 00000 10100 10001 Salvelinus larsoni 01011 01001 10100 01000 10202 00000 10100 10001 malma 01011 01001 10100 01000 10202 01000 11100 11001 alpinus 01011 01001 10100 01000 10202 01000 11100 11001 namaycush 1 11 1 1 01101 10100 01000 10202 00000 10100 11001 fontinalis 11011 01101 10100 01000 10202 01000 10100 11001 confluentis 11111 01101 20100 01000 10202 01000 11100 11001 leucomaenis 11011 01101 10100 01000 10202 00000 10100 11001 Salmo trutta 01011 01001 21100 01100 11102 01100 10100 10001 Salmo salar 01011 01001 21100 01 100 11102 01100 10100 10001 Oncorhynchus chrysogaster 01011 00101 21000 01100 10112 0?000 12100 01111 clarki 01011 00101 21000 01100 10112 01000 11100 00101 gilae 01011 00101 21000 01100 10112 0?000 11100 10101 apache 01011 00101 21000 01100 10112 01000 11100 10101 lacusiris 01011 00101 21000 01100 10112 01000 11100 00101 tnykiss 01011 00101 21000 01100 10112 01000 11100 00101 aguabonita 01011 00101 21000 01 100 10112 01000 11100 00101 (redband) OIOII 00101 21000 01100 10112 01000 11 100 00101 masou 01011 00101 21010 11 100 00002 01010 12100 00101 kisutch 01011 00101 21010 11100 00002 01010 12100 00101 tshawyischa 01011 00101 21010 11100 00002 01010 12100 00101 rastrosits 01011 00101 11010 11111 00011 01010 moo 00101 keta 01011 00101 11010 lino 00002 01010 12100 00101 nerka 01011 00101 11010 UNO 00002 01011 12100 00101 gorbuscha 01011 00101 11010 11110 00002 01010 11100 00101 SALMONID PHYLOGENY 33

TABLE A. 1. — Extended.

Character Taxon 81-85 86-90 91-100 101-110 111-119 Novumbra 00170 00000 00001 00100 00000 00100 00000 0000 Thaleichthys 000 10 00000 00200 00000 00000 00000 00000 0000 Chanos 00101 00010 00001 00100 10000 00000 00000 0000 Prosopium 00100 00011 00010 01000 00100 00001 00000 0000 Coregonus 00100 00111 001 10 01000 00112 00000 00000 0000 Stenodus 00100 00111 oiuo 01000 00112 00000 00000 0000 Thymallus 00100 0011> > 0 00011 01010 00100 00101 00000 0001 Eosalmo 00101 ?* * ?o 00011 1000? 99999 99999 99999 9999 Brachymystax 00111 10010 00011 10000 01102 00111 00000 0000 Acantholingua 00010 10010 01011 10100 00101 001?1 00000 0000 Salmothymus 10011 10010 01011 10100 11101 001?1 00000 0000 Platysahno 10011 10010 OlOil 10100 00100 00111 00000 0000 Hitcho hucho 10111 10110 01111 10101 01102 00121 00000 0000 Hucho pcrryi 10110 10000 01011 10001 01102 00121 00000 0000 Salvetinus larsoni 10110 10000 Q0999 99999 9J999 99999 ????? 9997 malma 10111 10000 01111 10100 11101 00121 10000 0000 alpinus 10111 10000 01111 10100 01101 00121 10000 0000 namaycush 10111 10000 02111 10100 01102 00021 10001 0000 fonlinalis 20111 10000 01011 10100 01101 00121 10001 0000 confluent is 10111 10000 02111 10100 01101 00121 10000 0000 leucomaenis 10111 10000 02011 10100 01101 00121 10001 0000 Salmo trittla 10011 10010 00011 10100 00101 00121 00000 0000 Salmo salar 10011 10010 01011 10100 00101 00121 00000 1000 Oncorhynchus chrysogastcr 20111 10010 00011 10000 00101 00121 01010 0000 clarki 20111 10000 01111 10000 00101 00121 01010 0000 gilae 20111 10010 11111 10000 00101 00121 oino 0000 apache 20111 10010 11111 10000 00101 00121 OHIO 0000 locust ris 20111 10??0 11??? 99990 09999 99999 99999 7777 mykiss 20111 10010 11111 10000 00101 00121 00010 0000 aguabonita 20111 10010 01111 10000 00101 00121 01010 0100 (red band) 20111 10010 11111 10000 00101 00121 01010 0000 masou 21111 10010 12111 10100 00101 00121 00010 0010 kisutch 21111 10010 12211 10000 00102 00121 00000 0000 ishawytscha 21111 10010 12211 10000 00102 00121 00000 0000 t i rastrosus 11111 79770 \2 > *t 99990 |9999 99999 ????? 9999 keta 21111 11010 12211 10100 00102 00121 00000 0000 nerka 11111 11010 12211 1 0000 10102 10121 00000 0000 gorbuscha 2IIII IIOIO 12211 10000 10102 11121 00000 0000