BULLETIN OF MARINE SCIENCE, 52(1): 60-1 L3, 1993

COMPARATIVE MORPHOLOGY OF SPINED SCALES AND THEIR PHYLOGENETIC SIGNIFICANCE IN THE TELEOSTEI

Clive D. Roberts

ABSTRACT The organization and morphology of spined scales are described from a broad-based survey of body scales of teleost fishes using scanning electron microscopy and light microscopy. Three general types of spined scale are recognized (I) crenate: simple marginal indentations and projections, (2) spinoid: spines continuous with the main body of the scale, and (3) ctenoid: spines separate from the main body of the scale, in two common configurations of transforming or peripheral ctenoid and a rare configuration of whole ctenoid. Crenate scales occur widely in the Elopocephala; spinoid scales occur widely in the Euteleostei; peripheral ctenoid scales have a restricted distribution in the Euteleostei, occurring probably indepen- dently in the Ostariophysi, Paracanthopterygii, and Percomorpha; transforming ctenoid scales are a unique specialized form of spined scale, and are a synapomorphic character diagnosing the Percomorpha; whole ctenoid scales are known from only two percomorph genera. The greatest diversity of spined scales is found in the Ostariophysi and the Percomorpha. Spined scales show great evolutionary plasticity, and it is suggested that changes in ontogenetic trajectory, as well as the evolution of new characters, contribute to the diversity of spinal structures observed.

The value of scale morphology in fish classification was recognized almost 160 years ago by Louis Agassiz who classified fishes on the basis of four scale types: "Les Placoides" (e.g., "Pastenagues, Raies, Squales") with spine-like denticles of enamel and dentine, "Les Ganoides" (e.g., "Esturgeons, Polypteres, Lepisostes, Goniodontes, Silures, Scleroderms, Lophobranches") with thick plates ofganoine and bone, "Les Ctenoides" (e.g., "Mugiloides, Gobiodes, Cottoides, Scienoides, Sparoides, Scorpenoides, Percoides, Pleuronectides, Chaetodontes, Polyacanthes, Aulostomes") having thin plates with comb-like posterior borders, and "Les Cy- cloides" (e.g., "Cyprinoides, Clupes, Salmones, Esocides, Gadoides, Anguilli- formes, Blennoids, Atherines, Scomberoides, Labroides") having thin plates with smooth borders (Agassiz, 1834, in Baudelot, 1873,100 and Patterson 1977,581). Although this classification was short-lived and unnatural, the nomenclature in- troduced by Agassiz has been fully incorporated into ichthyology. Since that time, the use of teleost scale morphology in fish systematics has generally been confined to notations of scales as simply either "cycloid" or "ctenoid," with little or no analysis and comparison of scale structure; with a few notable exceptions, it was widely believed that scales had "limited use in fish systematics" (Van Oosten, 1957,204). Contrary to this view, light microscope studies on scales by Williamson (1851); Baudelot (1873); Timms (1905); Cockerell (1910, 1913, 1914, 1915); Chu (1935); Lagler (1947); Kobayasi (1951, 1952, 1953, 1954, 1955); McCully (1961) and others, have demonstrated their high value in systematic studies, and have contributed significantly to our knowledge of scale morphology. More recently, the use of the scanning electron microscope (SEM) has revealed many new features of scale morphology as well as providing information on scale growth and development. SEM studies by workers such as DeLamater and Cour- tenay (1973,1974) and particularly Hughes (1981) have shown that the complex microstructure of ctenoid scales contains a wealth of potentially valuable, but largely unutilized, phylogenetic information (Johnson, 1984). In addition to their rich information content, scales have great utility in systematic research because

60 ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 61 they are usually readily accessible in live, fresh, preserved, and fossilized material. Unfortunately, this utility has not often been realized. Despite the wide use of the term, or perhaps because of it, there is considerable variation in the literature concerning the meaning of ctenoid. Many authors (often implicitly) apply a broad definition of ctenoid to all scales with spine-like pro- jections in the posterior field, with all other scale types being considered cycloid. Other authors apply a much stricter definition which only includes scales with spines that are separate from the scale (e.g., the "true" cteni of Johnson, 1984, and Starnes, 1988). The confusing corollary of ctenoid sensu stricto is that the alternative state of cycloid can include scales with spines (e.g., macrourids, Mar- shall and Iwamoto, 1973, 500, and Iwamoto, 1990, 90; priacanthids, Starnes, 1988, 120; Champsodon and Chiasmodon, Pietsch, 1989). Johnson (1984) rec- ognized the inadequacy of the two terms cycloid and ctenoid, and identified in the Percoidei two basic types of ctenoid scales: "Ct'" (scales with continuous spiny projections from the lateral surface and posterior margin) and "Ct" (scales with separate bony plates, or scalelets, that are continually added with growth). How- ever, these two types of cteni are generally not distinguished in systematic works. Percomorph fishes are ideal subjects for a study of comparative scale mor- phology because of the wide range of spined scale types exhibited together with the problematic nature ofpercomorph classification. The problems in percomorph phylogeny are largely due to the great morphological diversity and the limited num ber of descriptions and analyses of character complexes with which to generate corroborated hypotheses of monophyly, including the Series Percomorpha itself (see Johnson, 1993, and others in this issue). A survey of spined scales by the author began during an investigation into the relationships of the basal percomorph genus Polyprion (Roberts, 1986), and was expanded into a comprehensive broad-based study carried out on the extensive fish collection of the Smithsonian Institution during tenure of a Postdoctoral Fellowship. This paper reports the main results of the study, and shows that scale morphology is a valuable tool in the investigation of percomorph (and teleost) evolution.

MATERIALS AND METHODS

Scales were removed from the body taking care not to damage the posterior field. Unless otherwise dictated by the condition of the specimen, about six scales were removed from the right side of the body, either above or below the lateral line in the region of the pectoral fin. Lateral line scales and replacement scales were avoided where possible. Scales from recently preserved specimens were chosen in preference to older specimens which often have either damaged scales or an excess of foreign material adhering to their surfaces, although scales from specimens that had been in preservative for over 100 years were prepared successfully. In a pilot study, no difference was found in the quality of scale preparation between scales sampled from fresh or preserved specimens of the percoids Perea flaveseens and Lepomis maeroehirus. Therefore, preserved specimens were used throughout the study. Scales were examined with the light microscope (LM) and scanning electron microscope (SEM). Two types of examination were carried out: cursory study and detailed study. Cursory study was designed to quickly assess and identify scale morphology in a large number and wide phyletic distri- bution of fish taxa, and involved examination of unprocessed scales by transmitted light under a binocular dissecting LM. Detailed study was designed to investigate and identify the different types of spines and scale morphologies in key teleost lineages using both LM and SEM. Fish species sampled and type of scale preparation carried out on them are listed in Appendix I. Methods of scale preparation were initially modified from DeLamater and Courtenay (1974, 142), and involved bleaching in a solution of 9 parts 0.5% potassium hydroxide and I part 3% hydrogen peroxide followed by cleaning in a borax-trypsin solution for 2-5 days, and sonication in an ultrasonic water bath for about 10 sec. Although this initial method produced satisfactory preparations, it was time consuming and, therefore, the following quicker technique described by Hughes (1981), was used routinely for most of the study. Scales were cleaned by immersion in a 1% solution of sodium 62 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, ]993

hypochlorite for 5-30 min (Hughes, 1981, recommended using a cold solution, but a solution at room temperature worked equally well). Tissue adhering to both faces of the scale was gently teased off under a dissecting microscope using two small short-bristled nylon paint brushes (natural bristle was quickly damaged by the sodium hypochlorite). Time of immersion was critical because ifleft for too long the scale started to disarticulate. Cleaned scales were washed in 50% ethanol. Scales to be viewed with SEM were partly dried in air and mounted on a numbered aluminum specimen stub using double-sided sticky tape. Drying continued in air and was completed in a vacuum during coating. Curling was reduced by sticking scales on to a stub before they became completely dry, and was less severe when the scales were dried from 50% ethanol, rather than from distilled water or 100% ethanol. When dry, the scales and specimen stubs were sputter coated with gold to a thickness of 25-30 nm in a vacuum of about 40 x 10-3 torr. It was not necessary to coat them with carbon (as recommended by DeLamater and Courtenay, 1974, 142) prior to coating with gold. Scales were viewed using the secondary electron image of a Philips 505 SEM (Victoria University of Wellington) or Cambridge Stereoscan 100 SEM (National Museum of Natural History, Smithsonian Institution) at accelerating voltages of 10 or IS kY. Electron micrographs were taken on 4" x 5" format Polaroid Polapan type 52 instant sheet film, and occasionally on Kodak Tri-X Pan type 4164 negatives. Scales for LM study were stained with alizarin red S in a 0.5% potassium hydroxide solution for about 24 h. Permanent mounts were made by dehydrating in a series of 50, 75, 95,100, 100% ethanol, soaking in two changes of xylene, and mounting between a glass microscope slide and cover slip with Canada balsam. Curling of the scales was difficult to avoid, due in particular to the action of xylene, but was usually corrected or reduced by placing a 4-ounce lead weight on top of the cover slip while the mountant dried and hardened over a period of 2 to 5 days. Teleost classification and nomenclature (Fig. I) are based on the phylogenetic concepts ofteleostean relationships summarized by Lauder and Liem (1983), with modifications from Rosen (1985); Stiassny (1986); Sanford (1990); Begle (1991) and Johnson (1992). This cladistic phylogeny formed the basis whereby key lineages and taxa were identified and studied. Institutional abbreviations follow Leviton et al. (1985). Terminology for most scale features follows Lagler (1947); scale definitions, with ety- mology from Brown (1954) and Henderson et al. (1963), are as follows: Cycloid-(Greek "kyklos" circle, and "eidos" shape) scales with a smooth posterior margin, and lacking spines in the posterior field. Crenate-(Latin "crena" notch) seales with alternating notehes and flat projections forming the posterior margin, and lacking true spines in the posterior field. Spinoid-(Latin "spina" thorn or spine; Greek "eidos" shape) scales with complete whole spines arising directly out of the posterior field. Ctenoid-(Greek "kteis" comb; "eidos" shape) scales with discrete separately ossified spines in the posterior field.

RESULTS In addition to cycloid scales, three major types of spined scales, crenate, spinoid, and ctenoid, are recognized within the Teleostei (Appendix I) and are described below. Crenate Scales. - These are scales with outgrowths of the posterior margin as illustrated by the clupeid genus Anodontostoma by Whitehead (1985, 253), and reach their maximum development in the aulopiform Bathypterois (Fig. 2A, B). Scale growth appears to be by the relatively simple addition of marginal incre- ments, with larger increments occurring at the posterior margin to form the crenae. Spinoid Scales. - These are the Ct' type described by Johnson (1984), and have spines projecting posteriorly and sometimes laterally as continuations of the main body of the scale as seen in the characiform Ctenolucius (Fig. 2C, D). Growth appears to be relatively simple through marginal increments and continuous elon- gation of the spines as shown by the myctophid Notoscopelus (Fig. 2E), with additional spines being added laterally with increasing size as illustrated by the beryciform Sargocentron (Fig. 2G). Spines may also occur laterally as well as at the posterior margin. In the basal acanthomorph Polymixia (Fig. 2F), the lateral spines grow to a finite size, then are overtaken by further growth of the posterior field leaving a more-or-less alternating pattern of obliquely protruding spines. In some genera, lateral spines may grow directly out from the body of the scale to form large impressive buttressed projections as in the beryciform Stephanoberyx (Fig.2H). ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 63

Osteoglossomorpha

Teleostei Elopomorpha

Elopocephala Clupeomorpha

Esocae

Euteleostei Ostariophysi

Osmerae

Salmonoidei

Neoteleostei Stomiitormes

Aulopitormes

Myctophiformes Ctenosquamata

Polymixiidae Acanthomorpha

Paracanthopterygii

Acanthopterygii Atherinomorpha

Percomorpha

Figure I. Teleost phylogeny and nomenclature after Lauder and Liem (1983, and works cited therein), Rosen (1985), Stiassny (1986), Sanford (1990), Begle (1991) and Johnson (1992).

Ctenoid Scales. - These are more complex than the preceding forms and have discrete spines called cteni (singular ctenus) formed as separate ossifications. Cteni can be grouped into two main types: transforming cteni, the Ct type of Johnson (1984), which arise as whole spines in two or three alternating rows marginally and transform into truncated spines submarginally, e.g., the percoid Doederleinia 64 BULLETIN OF MARINE SCIENCE. VOL. 52. NO. I. 1993

Figure 2. Scanning electron micrographs (SEM's) of crenate and spinoid teleost scales. Size shown by bar in this and other SEM figures. A, B) Crenate scale from pectoral region of the aulopiform Bathypterois quadrifilis (Gunther), USNM 34963, 120 mm SL, bars = I mm. C, D) spinoid scale from the characiform Cteno/ucius beani (Fowler), USNM 293172, 164 mm SL, bars = I mm, 0.5 mm. E) The myctophid Notoscope/usjaponicus Tanaka, USNM 163285, 107 mm SL, bar = 0.5 mm. F) The ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 65

(Fig. 3A); and peripheral cteni, which occur as whole spines in one row (sometimes an alternating row of smaller secondary spines is also present) at the scale margin, as exhibited by the gobioid Gobiomorus (Fig. 3B). A third rare type, whole cteni, has separate whole spines marginally and submarginally (Fig. 20).

DESCRIPTION AND PHYLETIC DISTRIBUTION OF SCALES IN TELEOSTS Superorder Osteoglossomorpha The sister group to all other teleosts, comprising two monophyletic lineages: Osteoglossoidei (Osteoglossidae, Arapaimidae) and Notopteroidei (Mormyridae, Notopteridae, Hiodontidae); scales cycloid.

Superorder Elopomorpha Comprising three monophyletic lineages: Elopidae, Megalopidae, and Anguil- liformes (Albuloidea, Notacanthidae, Halosauridae, Anguilloidea, Saccopharyn- goidea); scales cycloid or crenate, spinoid and ctenoid scales absent; scales on Elops, Megalops, and Albula crenate with fragile membranous posterior field and irregular posterior margin (Fig. 4A, B); scales of Elops described by Merriman (1939, figs.A-D) as "extremely thin" with "saw-toothed" posterior margin giving "every appearance of being ctenoid," but they are clearly crenate.

Superorder Clupeomorpha Comprising two monophyletic lineages: Denticipitoidei (monotypic Denticipiti- dae) and Clupeoidei (Engraulidae, Chirocentridae, Dussumieridae, and Clupei- dae); scales mostly cycloid and thin or with thick keel-like scutes, crenate in some clupeid taxa: the genus Anodontostoma Bleeker has "toothed" scales (Whitehead, 1985, 252, figs.) which appear to be autapomorphic for the genus; species of Brevoortia have scales with "long weak teeth" (Cockerell, 1913, 125) and "hind edges pectinated with sharp points" (Whitehead, 1978); two species of Sardinella have scales with "crenate edges" (Meek and Hildebrand, 1923, 186, pI. IX); and a species of Sardinops has scales with "outer margin crenulated" (Shackleton and Johnson, 1988). Scales of clupeoids are distinctive, having transverse striae (=ra- dii) in the anterior field, and a membranous posterior field, often with longitudinal striae and posterior margins grading between cycloid and crenate (Fig. 4C, D). The characteristic morphology of clupeoid scales has previously given rise to their separate classification as "clupeoid," distinct from cycloid and ctenoid (Timms, 1905).

Infraorder Esocae Possibly the sister group to all other euteleosts (Fink and Weitzman, 1982; Sanford, 1990), comprising two monophyletic lineages: Esocidae and Umbridae; scales cycloid (with distinctive ridge ornamentation on radii) or crenate (scales on Esox with a deep notch, see Figs. 4E, F); spinoid and ctenoid scales absent.

+- polymixiid Po/ymixia /owei GUnther, USNM 202153, 120 mm SL, bar = 0.1 mm. G) The beryciform Sargocenlron diadema (LacepCde), USNM 303316, 55 mm SL, note lateral rudiments, bar = 0.5 mm. H) Buttressed fused spines in the beryciform Stephanoberyx monae Gill, USNM 83892,82 mm SL, bar = 0.2 mm. 66 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993

Figure 3. SEM's of teleost scales with cteni, bars = 0.2 mm. A) Transforming cteni on a scale of the percoid Doederleinia berycoides (Hilgendorf), USNM 151794, 181 mm SL. B) Peripheral cteni on a scale of the gobioid Gobiomorus maculalus (Castelnau), USNM 288007, 117 mm SL.

Figure 4. SEM's of crenate and cycloid scales from basal teleosts, bars = I mm except F. A) Mem- branous posterior margin in the albulid Albula vulpes (Linnaeus), USNM 300474, 174 mm SL. B) Membranous posterior margin of the megalopid Megalops allanticus (Valenciennes), USNM 303317, 88 mm SL. C) Membranous posterior field and irregular margin of dussumicriid Dussumieria acula ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 67

Valenciennes, USNM 276391, 116 mm SL. D) Membranous posterior field with longitudinal striae in the chirocentrid Chirocentrus dorab (ForsskAl), USNM 138961, 185 mm SL. E, F) Deep notch in posterior margin of esocid Esox americanus Gmelin, USNM 62781, 245 mm SL, bars = I mm or 0.5 mm. G) Crenate posterior field of cyprinid Cirrhina reba (Hamilton-Buchan un), USNM 165085, 91 mm SL. H) Whole cycloid scale of cyprinid Cyprinus carpio Linnaeus, USNM 30703, 62 mm SL. 68 BULLETIN OF MARINE SCIENCE, VOL. 52, NO, I, 1993

Figure 5. SEM's of ctenoid scales from the ostariophysan Gonorynchus gonorynchus (Linnaeus), USNM 39659, 316 mm SL, bars = 0.5 mm. A) Whole scale. B) Posterior field with cteni.

Superorder Ostariophysi A large clade, comprising four monophyletic lineages: Gonorynchiformes (Chanidae, Kneriidae, Phractolaemidae, Gonorynchidae), Cypriniformes (Cy- prinidae, Catostomidae, Gyrinocheilidae, Psilorhychidae, Homalopteridae, Co- bitidae), Characiformes (ca. 16 families), and Siluriformes (ca. 31 families); scales absent (e.g., all Siluroidei-Fink and Fink, 1981), cycloid (e.g., Cypriniformes- Chu, 1935, 16), crenate (some Cypriniformes), spinoid (some Characiformes), or peripheral ctenoid (monotypic Gonorynchidae and some Characiformes). Scales of a few cypriniforms develop crenae in the form oflongitudinal striae and irregular posterior margins (Fig. 4G, H). Spined scales are known to occur in fewer than 60 species of Ostariophysi, but great variation in spine morphology is shown among characiform taxa. The phylogenetically most primitive teleosts with ctenoid scales belong to the ostariophysan genus Gonorynchus (Fig. SA, B). The cteni are large, robust and complete; they grow in a single posterior row, are inward curving except for the middle ctenus, have complex interlocking bases, and are separate from the main body of the scale (observations supported by alizarin stained preparations). The middle ctenus is largest and lateral cteni progressively decrease in size, a pattern which suggests that the apical ctenus arises first and new cteni are added equally, one by one laterally, with increasing scale size. Gonorynchus is the only anoto- physan taxon with peripheral ctenoid scales. The Characiformes contain the only otophysan taxa with spinoid or ctenoid scales. Spinoid scales occur in five families (Citharinidae, Characidae, Ctenolu- ciidae, Curimatidae, Prochilodontidae) and can be tentatively grouped into two different forms characterized by a linear or an alternating pattern of spine growth. Two types of linear spinoid growth are present in Potamorhina (Curimatidae) and Ctenolucius (Ctenoluciidae). In Potamorhina (Fig. 6A, B) spines form irregular longitudinal ridges marked by growth increments and terminate in broad flat ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 69

Figure 6. SEM's of characiform spinoid scales. A, B) The curimatid Potamorhina pristigaster (Stein- dachner), USNM 242145, 231 mm SL, bars = I mm. C, D) The ctenoluciid Ctenolucius beani (Fowler), USNM 293172, 164 mm SL, bar = I mm or 0.5 mm. E, F) The prochilodontid Prochilodus nigricans Agassiz, USNM 280609, 104 mm SL, bars = I mm or 0.2 mm. G, H) The characid Galeocharax gulo (Cole), USNM 124890, 157 mm SL, bars = I mm or 0.2 mm. 70 BULLETIN OF MARINE SCIENCE. VOL. 52. NO. I. 1993

Figure 7. SEM's of ctenoid scales from distichodontid characiforms, bars = I mm or 0.2 mm. A, B) Distichodus rostratus Gunther, USNM 230093, 20 I mm SL. C, D) Eugnatichthys eetveldtii Bou- lenger, USNM 3] 0472, ]48 mm SL. E, F) Phago loricatus Gunther, USNM 303949, 122 mm SL. spines; in Ctenolucius (Fig. 6C, D) spines form smooth continuous ridges de- creasing in length laterally and each terminating in an acute spine. Two types of alternating spines are shown by Prochilodus (Prochilodontidae) and Galeocharax (Characidae). In Prochilodus (Fig. 6E, F; Cockerell, 1914, pI. XXIV) spines grow in approximately alternating rows forming small flat spines marginally and rem- nants submarginally which have fused into the posterior field, described by Cock- erell (1914, 96) as "apical margin finely irregularly dentate." In Galeocharax (Fig. 6G, H) acute spines form alternating rows which remain intact across most ofthe posterior field (although they may be broken from mechanical damage). Menezes (1976) described them as "true spines ... arranged in slightly irregular series, starting near the focus ... the number gradually increasing towards the upper margin." This alternating spinoid form is diagnostic of the characid subfamily ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 71

Figure 8. SEM's of spinoid scale from the argentinoid Argentina situs (Ascanius), USNM 187036 166 mm SL, bars = I mm. A) Whole scale. B) Posterior field. '

Cynopotaminae (Menezes, 1976), and its configuration was noted as similar to Macruridae in arrangement by Cockerell (1915, 156). Cteni occur on scales of members of the characiform family Distichodontidae. They form a distinctive single marginal row of closely abutting robust spines which are well separated from the main body of the scale (observations confirmed from alizarin stained scales) and have been described by Cockerell (1910) and Vari (1979). The cteni are subequal in size and appear to grow from the apex outwards with lateral growth of the scale. New cteni arise as separate small os- sifications laterally and grow in length until the size of older cteni is reached. In basal distichodontids, e.g., Distichodus (Fig. 7A, B), the similar size, robust shape and configuration of the cteni are pallisade-like; in more specialized genera, e.g., Euganathichthys (Fig. 7C, D) and Phago (Fig. 7E, F), the cteni are more acute. Ctenoid scales are autapomorphic for the Distichodontidae, a family of 15African characiform genera (Van, 1979). It is of interest to note that ctenoid scales appear to be absent in Neotropical characiforms. Cockerell (1914, 92) stated that "the strongly ctenoid Distichodontine type of scale is represented only by Ctenobrycon in America," but examination of Ctenobrycon from a range ofneotropicallocalities has shown that Cockerell was mistaken because discrete spines are absent (R. P. Van, pers. comm. pers. obs.).

Infraorder Osmerae Comprising two monophyletic lineages: Osmeroidei (Osmeridae, Retropinni- dae, Lepidogalaxiidae, Salangidae, Galaxiidae) and Argentinoidei (Argentinidae, Bathylagidae, Alepocephalidae, Searsiidae); scales mostly cycloid and thin or ab- sent, but two argentine species with spinoid scales. Posterior field of body scales of Argentina situs and ventral scales of A. sphyraena with small strong spines growing from the posterior margin and the lateral surface in alternating rows (Fig. 8A, B); described by Cohen (1964, 8, fig. 4) as scales with "strong spines ... often growing from posterior margin of scale as well as from lateral surface, thus im- parting a distinctly ctenoid appearance."

Suborder Salmonoidei Following the recent work of Sanford (1990), thought to comprise two families: Salmonidae and Coregonidae; scales cycloid, usually small and thin; crenate, spinoid and ctenoid scales absent. 72 BULLETIN OF MARINE SCIENCE, VOL. 52. NO. I. 1993

Order Stomiiformes The sister group to all other neoteleosts (Lauder and Liem, 1983, 144, fig. 14; Johnson, 1992), comprising the families: Gonostomatidae, Sternoptychidae, Pho- tichthyidae, and Stomiidae (sensu Fink, 1985); scales absent, cycloid (thin and deciduous), ventral keel plates, or spinoid (rarely). The sternoptychid Polyipnus tridentifer has spinoid scales ventrally on the caudal peduncle. The few body scales present are cycloid and thin, but those covering the subcaudal photophores have two to five strong spines crossing the distal part of the posterior field and protrude well beyond the posterior margin. The abdominal keel scales, modified into ar- mored scutes, are also spined posteriorly. A few other sternoptychids in the genera Argyropelecus and Polyipnus have spinoid scales which have been described as scales with "prominent denticles" or "spines" (Baird, 1971; Harold, 1989). A type of spinoid scale removed from the stomiiform Chau/iodus sloani and illus- trated by Roberts (1986, fig. 4.04B) has not been found again on other specimens examined during this study. In view of this, and the specialized cycloid scales described from Chau/iodus by Morrow (1964) and Fink (1985), it is concluded that spinoid scales are not naturally present on Chauliodus.

Order Aulopiformes Comprising two monophyletic lineages: Aulopoidei (Aulopidae, Chlorophthal- midae, Bathysauridae, Scopelosauridae, Bathypteroidae, Ipnopidae) and Alepi- sauroidei (Alepisauridae, Paralepididae, Omosudidae, Anotopteridae, Scopelar- chidae, Evermannellidae, Giganturidae, Harpadontidae, and Synodontidae); scales absent (e.g., Evermannellidae-Johnson, 1982, 69), cycloid (e.g., all Scopelarchi- dae-Johnson, 1982, 69), crenate or spinoid. Most scaled aulopiforms have cy- cloid scales, but a few possess both cycloid and spinoid scales. Spinoid scales are found dorsally on the aulopoids Aulopus japonicus (Fig. 9A, B),A. nanae, and A. purpurissatus (cycloid scales occur ventrally). Two alternating rows of irregular, short spines occur at the posterior margin, and traces of spines which have been overgrown and fused into the posterior field occur submarginally in two or three rows. Mead (1966, 20, 25) described the scales of A. nanae as "ctenoid; ... scales on head and sides of body with saw-like serrations, ... the cteni numerous and irregular in size," but clearly these are spinoid scales. Serrae-like crenae occur at the posterior margin of scales of the chlorophthal- mids Chlorophthalmus agassiz, C. brasiliensis (Fig. 9C, D) and Parasudis trucu- lentus. These crenae appear to be simple modifications of the posterior margin, described by Mead (1966, 181) as "weak serrations along the distal edge." Elongate crenae occur on scales located under the pectoral fin of the bathypteroid Bathypterois quadrifi/is (Figs. 2A, Band 9E, F). Mead (1966, 142) described these crenae as "finger-like projections, usually about 5 in number, as long as the diameter of the scale in adults." Counts made from eight crenate scales examined during the present study gave a range of six to eight crenae, some of which were bifurcate (Fig. 9E, F). In the paralepid Paralepis coregonoides, mid-lateral body scales are spinoid; described by Rofen (I966, 263) as "weakly ctenoid," these scales have spines formed by the posterior orientation and projection of scale circuli (Fig. 9G, H). The occurrence of these unusual but distinctive spinous circuli appears to be due to the reduction of the posterior field with the posterior expansion of the two lateral fields and their circuli. No other alepisauroids are known to possess spiny scales. ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 73

Figure 9. SEM's of aulopiform spined scales. A, B) Spinoid scale of the aulopoid Aulopus japonicus Gunther, USNM 150104, 120 mm SL, bars = I mm or 0.2 mm. C, D) Serrate crenae on scales of the chlorophthalmid Chlorophthalmus brasiliensis Mead, USNM 268435, 113 mm SL, bars = I mm. E, F) Elongate crenae on scales of the bathypteroid Bathypterois quadrifilis Gunther, USNM 34963, 120 mm SL, bars = I mm or 0.5 mm. G, H) Circuli spines on scales of the paralepid Paralepis coregonoides Risso, USNM 49347, 179 mm SL, bars = I mm or 0.2 mm. 74 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993

Figure 10. SEM's of myctophiform spinoid scales. A, B) The myctophid Myctophum selenops TAning, USNM 269483, 63 mm SL, bars = I mm or 0.2 mm. C) The myctophid Myclophum asperum Richardson, USNM 269478, 58 mm SL, bar = 0.2 mm. D) The lampanyctine myctophid Notoscopelus japonicus (Tanaka), USNM 163285, 107 mm SL, bar = I mm. E, F) The neoscopelid So/ivomer arenidens Miller, USNM 135928,217 mm SL, bars = 2 mm or 0.5 mm.

Order Myctophiformes The sister group of the Acanthomorpha which together constitute the Cteno- squamata, contains the families Myctophidae and Neoscopelidae (Johnson, 1992); scales cycloid (most Neoscopelidae- Nafpaktitis, 1977, 1; most Myctophidae- Nafpaktitis et at, 1977, 14), or spinoid. Spinoid scales are known to occur in five species of myctophiforms. Spinoid scales have been found on four myctophids: Myctophum affine, M. asperum, M. selenops (Myctophinae), and Notoscopelus japonicus (Lampanycti- nae), and have a single marginal row of strong spines each with a longitudinal ridge crossing the posterior field submarginally (Fig. lOA-D). New spines arise laterally (Fig. lOA, D) and grow to the same size as the older spines. Once this ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 75

Figure II. SEM's of polymixiid spinoid scales. A, B) Polymixia lowei Gunther, USNM 202153, 120 mm SL, bars = 0.1 mm. size is reached, the spines continue to grow at a similar rate, thereby maintaining their identity. A different type of spinoid scale occurs on the neoscopelid So/ivomer arenidens and forms an alternating marginal row of irregular spines with several alternating rows of fused remnants submarginally (Fig. 1DE, F). Like myctophid spines, new spines arise laterally, but in contrast with myctophid spines, new spines also arise along the posterior margin. These new spines appear to arise between and below the old marginal spines (Fig. 1OF). Once replaced marginally, the old spines become part of the posterior field leaving only a faint trace oftheir structure (Fig. 1OF).

Family Polymixiidae Thought to be the sister group of all other acanthomorphs (Stiassny, 1986), comprising only the genus Polymixia; scales spinoid, with alternating rows of marginal and submarginal spines (Fig. 11A, B).

Superorder Paracanthopterygii An ill-defined group, tentatively comprising the orders Percopsiformes (Aphre- doderidae, Amblyopsidae, Percopsidae), Gadiformes (Muraenolepidoidei, Ga- doidei, Macrouroidei, Ophidioidei, Bythitoidei), Batrachoidiformes, Lophii- formes, and Gobiesociformes (but see Patterson and Rosen, 1989); scales mostly absent or cycloid, spinoid or peripheral ctenoid in some percopsiforms, and spi- noid in some gadiforms. Peripheral ctenoid scales occur on the only extant aphredoderid Aphredoderus sayanus (Percopsiformes) (Fig. 12A, B). The cteni are large, robust, and complete, with acute points and expanded knobby bases which do not interlock; they grow in a single marginal row, separate from each other and from the rest of the scale (observations supported by alizarin stained preparations). The middle ctenus is largest, and all other cteni decrease in size progressively to dorsal and ventral margins. Although separated from the scale at their bases, the six most lateral cteni each articulate with a raised knob which is part of the main body of the scale (Fig. 12B). Six genera of fossil percopsiforms have been described: Amphiplaga, Asineops, Erismatopterus, Libotonius. Sphenocephalus and Trichophanes, and all have spined scales (Cockerell, 1913; Rosen and Patterson, 1969; Wilson, 1979). Amphiplaga has scales with a single marginal row of separate cteni, similar to Aphredoderus, 76 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993

Figure 12. SEM's of paracanthopterygian spined scales. A, B) Peripheral cteni on the scale of the aphredoderid Aphredoderus sayanus (Gilliams), USNM 231251, 66 mm SL, note articulation knobs on scale, bars = 0.5 mm or 0.1 mm. C, D) Spinoid scale of the percopsid Percopsis omiscomaycus (Walbaum), USNM 177322, 88 mm SL, bars = 0.5 mm or 0.1 mm. E, F) Spinoid scale of the macrouroid Macrourus carinatus Giinther, NMNZ P.I 1434, 245 mm TL, bars = 0.5 mm or I mm. and described by Rosen and Patterson (1969, 394, pI. 66) as "strongly ctenoid." Similarly, Trichophanes has about 15 or more very long, strong, sharp spines along the apical margin, and agrees "in all essential features with those of Aphre- doderus" which has "apical teeth articulated on the margin" (Cockerell, 1913, 153). Spines on the scales of the other fossil genera have been described as mar- ginal, strong, long and slender; although not specifically described as separate, they appear to be closer to the aphredoderid peripheral ctenoid type rather than the percopsid spinoid type described below. Spinoid scales occur on the scales of Percopsis (Percopsiformes) and macrourids ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 77

(Gadiformes), but the two types are quite distinct. In Percopsis the spines arise from the posterior margin, and they are short, robust and irregular in size and orientation (Fig. 12C, D). In contrast, macrouroid spines are never marginal but grow out submarginally from the lateral face of the posterior field and sometimes the focus (Fig. 12E, F) in a variety of shapes and sizes (Iwamoto, 1989, fig. 9); they usually conform to either a linear or an alternating pattern. In a tentative, but corroborated, cladistic phylogeny, Iwamoto (I989, 170, fig. 15) found scale spines (=spinoid scales) to be synapomorphic for the subfamilies Macrouroidinae (2 genera, 2 species), Trachyrincinae (2 genera, 6 species) and Macrourinae (ca. 32 genera, over 250 species).

Series Atherinomorpha The Atherinomorpha, the sister group to the Percomorpha with which it forms the Acanthopterygii, contains the sister orders Beloniformes (Adrianchthyoidei, Exocoetoidei) and Cyprinodontiformes (Aplocheiloidei, Cyprinodontoidei), and the questionably monophyletic Atherinoidei (Atherinidae, plus five other basal atherinomorph families); scales mostly cycloid, but crenate in one atherinid and spinoid in one exocoetoid and a few cyprinodontoids. Spined scales have been found in four of the 830 atherinomorph species. Crenae, in the form of rounded posterior corrugations, have been found on scales ofIarger specimens of the atherinid Craterocephalus mugiloides by Crowley and Ivantsoff (I988, 158, fig. 2). This species appears to be the only atherinoid with spine-like scale development. Spine-bearing scales, described as "ctenoid," have been used as a diagnostic character to distinguish the exocoetoid belonid Pseudotylosurus angustieeps from its sister species (Collette, 1974). One to four elongate round-tipped spines grow in a roughly alternating pattern from the posterior scale margins in both sexes (Wiley and Collette, 1970, fig. !OF); these are, therefore, spinoid scales. Spinoid scales occur on the cyprinodontoid poeciliid Xenodexia ctenolepis (Fig. 13A, B). One or two rows of barely alternating small acute spines arise from the body of the scale along its posterior margin. On scales where two rows of spines occur, the proximal row is identified only by scars denoting the earlier position of spines which were overgrown by the distal row. This distinctive configuration suggests that growth of the second (distal) row replaces the first row of spines, but ceases before a complete second row has developed. These spinoid scales have been described in detail by Hubbs (I950, pI. III), who considered them to be unique among cyprinodonts. He described the spines as "hard needle-sharp den- ticle-like structures, similar to the ctenii of acanthopterygian fishes." Hubbs (I 950) noted that the spined scales cover most of the body except the head and adjacent areas of males, females, and juveniles alike and, therefore, should not be confused with the cilia-like nuptial organs of breeding males of some cyprinodonts. Rosen and Bailey (I963, 141) treated the monotypic subfamily Xenodexiinae erected by Hubbs (1950) and erroneously described the scales as "ctenoid" with spines sep- arate from the scale. The presence of"ctenoid" scales has also been recorded for the cyprinodontoids Cyprinodon variegatus (Cyprinodontidae), Poeciliopsis, and Lamprichthys tan- ganicanus (Poeceliidae) (Rosen and Bailey, 1963). Lamprichthys tanganicanus (Fig. 13C, D) and two species of Poeciliopsis (Fig. 13E, F) were examined during the present study (Appendix I), but all their scales were found to be cycloid. Assuming that the specimens were correctly identified, my observations indicate that spined scales are not present in these taxa, a conclusion supported by the 78 BULLETIN OF MARINE SCIENCE, YOLo 52, NO. I, 1993

Figure 13, SEM's of atherinomorph cyprinodontoid poeciliid scales. A, B) Spinoid scale from Xe- nodexia ctenolepis Hubbs, USNM 204247, 43 mm SL, bars = I mm or 0.2 mm, C, D) Cycloid scales from Lamprichthys tanganicanus (Boulenger), USNM 246600, 99 mm SL, bars = I mm or 0,2 mm, E) Cycloid scale from Poeciliopsis infans (Woolman), USNM 245972, 49 mm SL, bar = 0,5 mm, F) Cycloid scale from Poeci!iopsis turrubarensis (Meek), USNM 245979, 52 mm SL, bar = 0.5 mm. results of a survey of cyprinodont scales by Hollander (1986). Possibly bony breeding tubercles or nuptial contact organs which occur on fin rays and scales in many male cyprinodontiforms (Rosen and Bailey, 1963; Wiley and Collette, 1970) may have been mistaken for spined scales. In support of this interpretation, it is probably significant that the calcified projections described in Cyprinodon variegatus by Rosen and Bailey (1963, fig. 3B) were on scales from the head and nape of a breeding male. ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 79

Figure 14. SEM's of gasterosteiform aulostomid ctenoid scale. A, B) Peripheral cteni on scale of Aulostomus maculatus Valenciennes, USNM 285819, 395 mm SL, bars = 0.5 mm or 0.2 mm.

Series Percomorpha This is a large and diverse group of acanthopterygian fishes with uncertain composition, limits, and intrarelationships. Following the tentative scheme of Lauder and Liem (1983, fig. 50) and incorporating my own numbered grouping of convenience, the Percomorpha sensu lato comprises (Group I) the specialized orders Lampridiformes, Gasterosteiformes (Gasterosteiodei, Syngnathoidei, Au- lostomoidei), Pegasiformes, and Dactylopteriformes, and (Group II) the ques- tionably sister orders Beryciformes and Zeiformes (Rosen, 1984), which may be most closely related to (Group III) the polytomy of Perciformes, Scorpaeniformes, Tetraodontiformes, Pleuronectiformes, Channiformes, and Synbranchiformes; scales absent, cycloid, crenate, spinoid, transforming ctenoid, or peripheral cte- noid. GROUPI. Scales absent or cycloid (Lampridiformes), armored scutes (most Gasterosteiformes, Pagasiformes, Dactylopteriformes), or peripheral ctenoid (Au- lostomidae). Scales of the aulostomid Aulostomus have a single marginal row of partly overlapping large robust cteni, separated from each other and the main body ofthe scale (Fig. 14A, B). These ctenoid scales have been illustrated by Maul (1959, fig. IA-C), and described in detail by Jungersen (1910, 270-271)as "ovoid, with truncate hind margin, along which is a single row of large teeth" which are "independent structures, separated from the scale-plate, dropping off when mac- erated the middle teeth are largest, the size evenly decreasing towards the margins The median tooth apparently is the oldest, and new teeth are formed in pairs, one on each side of the first." Aulostomus appears to be the only taxon in Group I with ctenoid scales. GROUPII. Scales absent (Rondeletiidae, Cetomimidae), cycloid (Melamphaidae, Gibberichthyidae, some Zeidae, some Oreosomatidae), modified into armored plates (Monocentridae), modified into pedicel supporting rugose cup (Anoplo- gasteridae), mostly spinoid; development of bony scutes widespread. There are three general types of Group II spinoid scales: a single marginal row of spines, 80 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993

alternating rows of marginal and submarginal spines, and approximately alter- nating rows of laterally projecting spines. A single marginal row of spines characterizes scales of the beryciform family Holocentridae (Fig. 15A, B). There is some variation between species in the development and size of posterior field longitudinal ridges and their contiguous marginal spines (see illustrations in Woods and Sonoda, 1973), but the spines are consistently large, robust, and acute; usually the middle spine is longest, with new spines arising progressively laterally and total number increasing with growth of the scale (Randall and Heemstra, 1985; this study), The trachichthyid Hoplosteth- us atlanticus appears to be the only non-holocentrid in Group II with a single marginal row of spines, but these can be distinguished by being lighter, broader, and shorter (Woods and Sonoda, 1973, fig. 20) than holocentrid spines. Alternating rows of marginal and submarginal spines are found widely in Group II, including the beryciform families Berycidae, Trachichthyidae, and Diretmidae, and the zeiform taxa Cyttus (Fig. 16A, B), Capromimus (Zeidae), Neocyttus, Al- locyttus (Oreosomatidae), Zenion (Zeniontidae), Grammicolepis, and Xenolepi- dichthys (Grammicolepidae). In some zeiforms, this type ofspinoid configuration is substantially modified, with either reduced numbers of spines (e.g., Zenion, Allocyttus), or increased numbers of minute spines (e.g., Capromimus, Xenole- pidichthys, Grammicolepis). Laterally projecting spines characterize scales ofthe beryciform stephanoberyc- ids Stephanoberyx (Fig. 15C) and Acanthochaenus, and the zeiforms (Fig. 16C- F) Capros and Antigonia. Buttressed spines, in approximately alternating rows, arise from the lateral surface of the posterior field and also posterior areas of the anterior and lateral fields. The growth process is unclear, but it appears from their fused position on top of the focus and circuli that the lateral spines grow after the supporting body of the scale has formed. Size, form, and configuration of these spines differ considerably among genera. In Stephanoberyx (Fig. 15C) and Capros (Fig. 16C, D) the lateral spines are slender and firmly attached to the scale surface by expanded butresses; there are no spines at the scale margin. In Antigonia (Fig. 16E, F) the lateral spines are thorn-shaped with one to four acute points, they are loosely attached to medial parts of the anterior and lateral fields (note in Fig. 16F attachment scars of two lateral spines dislodged by the cleaning action of sodium hypochlorite), and there is an irregular row of spines posterior at the scale margin. This unique form of spined scale has been described and illustrated by Berry (1959, fig. 2). GROUP III. Scales absent or cycloid (Synbranchiformes, some Channiformes), modified plates and spinules (some Tetraodontiformes), crenate (some Perci- formes and some Scorpaeniformes), spinoid (some Tetraodontiformes), and cte- noid or one of the above types (Perciformes, Scorpaeniformes, Pleuronectiformes). Crenate Scales. - These occur on a few perciforms and scorpaeniforms (Appendix I), and comprise irregular modifications to the posterior margin into simple pro- jections and indentations, often occurring together with cycloid scales on the body. Perciforms recorded with crenate scales include the scombrid Scomber scombrus, described by Cockerell (1913, 149) as having "apical margin ... irregularly den- tate, without the formation of definite structures like those on genuinely ctenoid scales"; the carangids Elagatis bipinnulatus and Naucrates ductor, described by Zheng (1981, figs. 2-4) as "scales ctenoid" in the "caudal peduncle region"; and the plesiopidsAcanthoplesiops indicus and Behops batanensis, described by Smith- Vaniz and Johnson (1990, fig. 21G, H) as being neither ctenoid nor cycloid, but having posterior body scales with "membranous flaps ... often bi-or tri-lobed." ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 81

Figure 15. SEM's of beryciform spinoid scales. A, B) Sargocenlron diadema (Lacepede), USNM 303316, 128 & 55 mm SL, bars = 2 mm or 0.5 mm. C) Slephanoberyx monae Gill, USNM 83892, 82 mm SL, bar = 0.2 mm. 82 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993

Figure 16. SEM's of zeiform spinoid scales. A, B) The zeid Cyttus australis (Richardson), USNM 177052, 171 mm SL, bars = 1 mm or 0.2 mm. C, D) The caproid Capros aper (Linnaeus), USNM 268912, 78 mm SL, bars = 0.5 or 0.1 mm. E, F) The antigoniid Antigonia capros Lowe, USNM 163521,81 mm SL, bars = 1 mm or 0.2 mm.

Scorpaeniforms with crenate scales include the scorpaenids Apistus alatus and Setarches julzensis, described by Zhu and lin (1981, figs. 4, 20) as "very thin and cycloid ... the posterior margin ... divided into 3-8 lobes." During the present study, the scales of Scomber scombrus were found to be cycloid, and scales of the carangids Elagatis bipinnulatus and Naucrates duct or were only feebly crenate without the lobate projections illustrated by Zheng (1981). These observations suggest that there is considerable intraspecific variation in the development of crenate scales. Spinoid Scales. - These occur on some perciforms, scorpaeniforms, pleuronecti- forms, and tetraodontiforms (Appendix 1); they are morphologically diverse, in some cases appear to be highly modified, and comprise at least five forms: type 1, a subequal or irregular row of spines at the posterior margin; type 2, alternating ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 83

Figure 17. SEM's ofpercomorph group III spinoid scales type I. A, B) The scorpaenidEbosia bleekeri (Steindachner & Doderlein), USNM 169175, 81 mm SL, bars = 0.5 mm or 0.2 mm. C, D) The gempylid Ruvettus pretiosus Cocco, USNM 307216, 241 mm SL, bars = 0.1 mm, one of two type I forms and a cycloid form present (Bone, 1972). E, F) The bramid Brama brama (Bonnaterre), USNM 240541,82 mm SL, bars = 0.5 mm. or linear submarginal rows of spines orientated posteriorly with, or without, marginal spines; type 3, submarginal spines arising from the posterior field and orientated laterally; type 4, one to several spines arising from the middle of the scale and orientated laterally or posterolaterally; type 5, spines on the pedicel elevated above the scale. Type 1 spinoid.- These scales have a marginal row of robust, acute spines, similar to holocentrid spines (see above), which may be confined to the posterior margin (e.g., Ebosia bleekeri, Ruvettus pretiosus, Fig. 17A-D; Parapterois heter- urus, this study; Brachypterus serrulatus, Zhu and lin, 1981; Pristigenys serrula, Cookeolus japonicus, Starnes, 1988, fig. 2b, h; Howella brodiei, Roberts, 1990) or arise from ridges crossing the posterior field (e.g., Brama brama, Fig. 17E, F; Pristigenys meyeri, Heteropriacanthus cruentatus, Starnes, 1988, fig 2c, g). 84 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993

Figure 18. SEM's of percomorph group III spinoid scales type 2. A, B) The ostracoberycid Ostra- coberyx dorygenys Fowler, USNM 168442, 134 mm SL, bars = 0.5 or 0.1 mm. C) The pomatomid Pomatomus sa/latrix Linnaeus, USNM 302369, 131 mm SL, bar = 0.1 mm. D) The scatophagid Scatophagus argus (Linnaeus), USNM 173518, 160 mm SL, bar = 0.2 mm. E, F) The pomacanthid Pomacanthus semicircu/atus (Cuvier), USNM 295452, 103 mm SL, bars = 1 mm or 0.5 mm.

Type 2 spinoid.- These scales have submarginal spines in alternating rows (e.g., Ostracoberyx dorygenys, Pomatomus saltatrix, Scatophagus argus, Fig. l8A-C; Engyprosopon xystrias, Amaoka, 1969, fig. 51D); Priacanthus bloch ii, Priacanthus meeki, Starnes, 1988, fig. 2e, f) or in linear rows (e.g., Pomacanthus semicirculatus, fig. 18E-F; Maxillicosta raoulensis, Rosenblattia robusta, Zebrasoma veliferum, this study; Maxillicosta reticulata, Eschmeyer and Poss, 1976, fig. 2a) with or without spines at the posterior margin. Type 2 spinoid scales without spines at the posterior margin are very similar in appearance to macrourid scales. Note that submarginal spines of Scatophagus argus (Fig. l8D) are unusual because they occur outside the posterior field in the distal areas of the anterior and lateral fields, a configuration also found on scales of Antigonia (Fig. l6E-F). ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 85

Figure 19. SEM's of percomorph group III spinoid scales types 3, 4 and 5. A, B) Type 3, the bothid Achiropsetta trichofepis Norman, NMNZ P.20720, 154 mm SL, bars = I mm or 0.2 mm. C, D) Type 4, the monacanthid Parika scaber (Bloch and Schneider), USNM 304934, 134 mm SL, bars = I mm or 0.2 mm. E, F) Type 5, the champsodontid Champsodon sp., USNM 297751, 56 mm SL, bars = 0.5 or 0.1 mm.

Type 3 spinoid.- These scales have elongate spines that arise more or less perpendicular to the scale in the posterior field (Achiropsetta tricholepis, Fig. 19A, B). Although distinctive, this configuration is uncommon in percomorphs, having been found to date only in the bothid (achiropsettid) genus Achiropsetta. Type 4 spinoid.- These scales lack division into fields and are not closly im- bricated; they have one or more stout, often buttressed and recurved, spines which arise submarginally, generally from the central region; shape of scale base is often circular (e.g., Parika scaber, Fig. 19C, D; Zanclus cornutus, Tripodichthys bloch ii, this study; Luvaridae, Tyler et al., 1989, fig. 15; Chiasmodontidae, Pietsch, 1989, 288; juveniles of some Istiophoridae and Xiphiidae, Nakamura, 1985; Aploac- 86 BULLETIN OF MARINE SCIENCE. VOL. 52. NO. I, 1993

Figure 20. SEM's of whole ctenoid scales showing marginal and submarginal rows of separate com- plete cteni, bars = 0.5 mm or 0.1 mm. A, B) The epigonid Epigonus telescopus (Risso), USNM 305950, 241 mm SL. C, D) The mugiloid Mugil cephalus Linnaeus, USNM 187267, 114 mm SL. tinidae, Poss and Eschmeyer, 1978, and Eschmeyer and Allen, 1978; some Con- giopodidae, Moreland, 1960; Hureau, 1971; Paulin and Moreland, 1979; some Cottidae, McAllister and Lindsey, 1961; Nelson, 1984; Fujita and Kamei, 1984; most Triacanthodidae and Monacanthidae, Berry and Vogele, 1961; Tyler, 1968, 1980; Tyler and Lange, 1982; Matsuura, 1982; Hutchins, 1986; some Molidae, Tyler, 1980). Type 5 spinoid.- These scales lack division into fields, have an embedded base, and are circular in shape but not closely imbricated or overlapping adjacent scales, with a bony pedicel elevated above the scale base supporting robust spines growing out of the posterior and lateral margins (e.g., Champsodon sp., Fig. 19E, F, and Pietsch, 1989; some Cottidae, Nelson, D., 1984) or out of the lateral surface (e.g., Naso lituratus, this study). Ctenoid Scales. - These have spines which are separate ossifications from the scale plate and consist of whole, transforming or peripheral cteni; scales with whole cteni submarginally have a very limited distribution (two genera known), but transforming and peripheral cteni occur on many perciforms, scorpaeniforms and pleuronectiforms (Appendix 1). Whole ctenoid.- These scales have marginal and submarginal whole spines forming several approximately alternating rows in the posterior field; marginally the cteni arise as independent elements, but laterally they arise directly from circuli; the growth pattern produces two zones, a distal zone formed by approx- imately four to six rows of separate whole cteni and a proximal zone formed by approximately one to four rows of whole cteni fusing partly or completely to the main body of the scale; transforming cteni (see below) are absent; known only ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 87

Figure 21. SEM's of transforming cteni showing marginal rows of complete spines and submarginal rows of truncated spines on posterior field of perciform, scorpaeniform and pleuronectiform scales. A, B) The percid Perea flaveseens (Mitchill), USNM 241630, 73 mm SL, bars = 0.1 mm. C) The moronid Lateo/abraxjaponieus (Cuvier), USNM ]83848, 285 mm SL, bar = 0.2 mm. D) The serranid Epinephe/us nigritus (Holbrook), NMNZ uncat., 377 mm SL, note two developing marginal cteni, bar = 0.5 mm. E) The hexagrammid Hexagrammos ste//eri Tilesus, USNM 21530, 210 mm SL, bar = 0.2 mm. F) The citharid Citharoides maero/epidotus Hubbs, USNM 26]528, 104 mm SL, bar = 0.2mm. from two species of epigonid (e.g., Epigonus telescopus, Fig. 20A, B) which have long slender cteni with rounded tips and irregular slightly expanded bases, and one mugiloid (MugU cephalus, Fig. 20C, D) which has lanceolate cteni with pointed tips and expanded bases. There are few literature accounts of these scales and most lack clear description of the cteni. Scales of epigonids have been described simply as "large, deciduous and ctenoid" by Mayer (1974, 151), but Johnson (1984,483) recognized that they are different from scales with transforming cteni. The cteni of Mugil cephalus have been described as "narrow, slightly curved, 88 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993 A B CTENUS SUBCTENUS

DEVELOPING

ii FULLY-FORMED

iii DEGENERATING SPINE

iv TRUNCATED SPINE, (j BASE SEPARATE

V .;,r"::;:.,

.",' BASE FUSED ..... -', .', '.::.:::,:.:' . ":-,::,,

BASAL PERCOMORPH CTENUS ONTOGENY Figure 22. Transforming ctenial ontogeny shown diagrammatically to illustrate changes with growth. A) Ctenial development. B) Subctenial development. keeled, and sharply pointed" by Jacot (1920, 225, figs. 20-25) and Pillay (1951, 417, fig. Ib) and illustrated as whole cteni submarginally (also see Kobayasi, 1953, fig. 9). There is considerable variation in the type of scale in mugiloids (Appendix I; Pillay, 1951), but whole ctenoid scales have been found only in Mugil cepahlus. However, some mugiloids with transforming ctenoid scales only lose the tips of the cteni submarginally and their scales resemble those of Mugil celphalus. Transforming ctenoid. - These scales vary considerably in size and shape among taxa (Fig. 21; Cockerell, 1913; Kobayasi, 1953; McCully, 1961), but their general configuration is remarkably constant, strongly suggesting that they are produced by a common development process. Transforming ctenial ontogeny is shown diagramatically in Fig. 22. The new ctenus forms at a discrete center of ossification at the posterior margin of the scale (Figs. 21D, 22Ai), and grows into a separate fully formed ctenus (Fig. 22Aii) comprising distal spine and proximal lobate base (Fig. 23A). The spinous part of ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 89

Figure 23. SEM's of transforming cteni, bars = 0.05 mm. A) A single fully formed ctenus removed from the marginal zone of the scale from the scorpaenid Sebastes marinus Linnaeus, USNM 154809. 143 mm SL, showing distal spine (s) and proximal lobate base (b), in oblique ventral view. B) Truncate cteni from basal zone 3 of a scale from the percid Perea flaveseens (Mitchill), USNM 241654, 158 mm SL, after removal of marginal and medial zones by 18-h immersion in 1% sodium hypochlorite solution. 90 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993 the ctenus then degenerates into a truncated spine and base separate from its neighbors (Fig. 22Aiii-iv). Finally, the spinal remnant and associated base become fused with adjacent spinal remnants and bases to form a solid calcified plate (Figs. 22A v, 23B). Similar development is shown by subcteni (Figs. 22B, 24), except that subcteni are usually asymmetrical due to their lateral position, and they initially arise out of one or more circuli before becoming truly separate elements (Figs. 22Bi, 24), as also illustrated by Hase (1911, fig. 24), Cockerell and Moore (1910), and others. Growth of the posterior field occurs posteriorly by the addition of a row of cteni along the posterior margin, and laterally by the corresponding addition of two subcteni, one at each end of the row of marginal cteni. Based on studies of scales from juvenile Perea j/uviatilis and Aeerina eernua (Hase, 1911; Rosen, 1915), and my observations of ctenial patterns in the posterior field of many basal percomorphs, early ctenial growth usually begins with the development of a single ctenus located at the middle of the posterior field adjacent to the focus. It appears from the work ofHase (1911) and Rosen (1915) that the first ctenus initially arises directly from the posterior field and becomes separated from the scale secondarily. The formation of the first ctenus is followed by development of two subcteni, one on each side of the first ctenus, then development of the next row with two lateral subcteni and two medial cteni, and development of further rows comprising two subcteni and three, then four, then five medial cteni, and so on. This development can be summarized by the growth formula: 1 > ii > i+2+i > i+3+i > i+4+i > i+ 5+i, etc. (Roman numerals = subcteni, Arabic numerals = cteni, > = growth of new row alternating distally with the preceding row). The developmental pattern of cteni is often imperfect, however, and small deviations from this formula are common, especially in rows with large numbers of cteni. My observations concur with those of Hughes (1981), who stated that as the scale increases in size the net effect is the addition of one ctenus per row. The growth pattern of transforming cteni is distinctive and usually produces three zones in the posterior field (Fig. 24; Hughes, 1981). The marginal or outer zone is formed by two or occasionally three alternating rows of separate cteni, and two subcteni, one at the end of each row. The medial zone is formed by usually two or three rows of separate truncated cteni, and laterally by truncated subcteni. The third or basal zone is formed by the truncated ctenial and subctenial bases fusing together (Fig. 24) to form a solid calcified plate. The relative sizes of the medial and basal zones varies among taxa, with apparent reduction in number of rows of ctenial bases being common. One exception to this general growth pattern is found in the pleuronectiform genus Psettodes which has transforming cteni orientated in simple lines radiating across the posterior field (Amaoka, 1969, fig. 2E). Other differences between typical transforming ctenoid scales are that in Psettodes scales the cteni are not differentiated in shape into spine and expanded base, there is no clear distinction between cteni and subcteni, cteni arise as com- plete spines in only one marginal row, there is little lateral fusion submarginally between truncated cteni, and there are not three distinct zones in the posterior field. Nevertheless, the scale spines arise as separate elements and transform submarginally; they are, therefore, transforming cteni. There are numerous descriptions of transforming cteni on the scales of perci- forms (Baudelot, 1873; Ganguly and Mookerjee, 1947; Lagler, 1947; Kobayasi, 1953; McCully, 1961, 1970; DeLamater and Courtenay, 1974; Johnson, 1984), scorpaeniforms (Hughes, 1980, 1981; Zhu and Jin, 1981; Poss and Collette, 1990) and pleuronectiforms (Baudelot, 1873; Batts, 1964; Amaoka, 1969; DeLamater and Courtenay, 1973; Menon, 1977), but only a few studies (Cockerell, 1913; ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 91

Figure 24. SEM's of part of the posterior field of a ctenoid scale from the cynoglossid Symphurus tessellatus (Quoy and Gaimard), USNM 300485, 140 mm SL, showing three zones formed by ctenial development. A) Zones 1-3; note two lateral subcteni, and line of truncated subcteni at the junction of the posterior and lateral fields, bar = 0.2 mm. B) Junction of medial zone 2 and basal zone 3; note fused bases of basal zone, bar = 0.05 mm. I: Marginal or outer zone with separate cteni (c) and subcteni (s). 2: Median zone, formed by rows of scparate truncated cteni and laterally by truncated subcteni. 3: Basal zone, formed by truncated ctenial and subctenial bases fusing together to form a solid calcified plate. 92 BULLETIN OF MARINE SCIENCE, VOL. 52, NO.1, 1993

Hughes, 1981; Roberts, 1986) record transforming cteni occurring on taxa in all three orders. Transforming cteni do not occur on the scales of non-percomorph teleosts. Williamson (1851) and Baudelot (1873) were among the earliest workers to record whole spines marginally and bases of spines submarginally in the posterior fields ofpercomorph scales. Williamson (1851,653) described transforming cten- ial growth in Percafluviatilis as the addition of new marginal teeth, behind which numerous bases of similar teeth appear to have been worn away prior to the development ofa new series. Subsequent to Williamson's (1851) interpretation that submarginal cteni are abraded, there has been conflicting explanation of spine loss. McCully (1970) proposed that a thin line of osteoclastic cells remove calcified material producing an amputation gap which cuts off the tip of the spine leaving behind a spinal base. Hughes (1981) reached a different conclusion using McCully's observations, supported by her own detailed SEM study. She interpreted the mechanism for spine loss as a progressive resorption because degrading spines of all intermediate sizes were found, indicating a gradual reduction in length rather than a sudden loss. Results similar to those of Hughes (1981) were obtained by the present study, and these support the resorption theory. Peripheral ctenoid. - These scales have discrete spines in one row at the pos- terior margin of the scales of many perciforms (this study), some scorpaeniforms (Zhu and Jin, 1981; Poss and Collette, 1990) and some pleuronectiforms (Amaoka, 1963a, 1963b, 1969) (Appendix 1). All scales with peripheral cteni are charac- terized by a posterior focus and greatly reduced posterior field, a configuration that probably reflects lateral growth rather than the more usual combination of lateral and posterior scale growth. Peripheral cteni are usually stout and acute with expanded bases (Figs. 25, 26), except in some bothids which have elongate cteni (Amaoka, 1963a, 1969). The relative sizes of cteni vary between sub equal (Fig. 25A, B), unequal and irregular (Fig. 26C), unequal progressively increasing in size laterally to about the three most lateral cteni (Figs. 25C, D, 26A; most common in Gobiidae and Eleotridae, Kobayasi, 1953; Takagi, 1953; this study), or unequal in an alternating pattern of primary (large) and secondary (small) cteni (e.g., Fig. 25E, F; Appendix 1; Anthiinae, McCully, 1961; Callanthiidae, Anderson and Johnson, 1984; Pseudochromidae, McCully, 1961 and Hoese and Gill, 1993; Gobiidae, Kobayasi, 1953). Secondary cteni may also occur irregularly as indi- vidual spines scattered among other growth forms of peripheral cteni. The discrete nature of peripheral cteni was noted last century by Vaillant (1875) who concluded from a light microscope study of the scales of Gobius niger that the cteni and scale develop in an independent manner, and that the ctenial bases are separated from the scale by a gap containing longitudinal fibers. Similar results were obtained more recently by Fouda (1979) who found in the goby (Pomatoschis- tus microps that the calcium/phosphorus molar ratio and ultrastructure of pe- ripheral cteni differed from those of the scale; the cteni are separated from the scale by uncalcified collagen fibers; and ctenial growth occurs by secretions of ctenial rather than scale osteoblasts. The details of early development of peripheral cteni are still unclear, but Vaillant (1875) concluded that development started with growth of a medial spine, proceeding with lateral pairs in a regular manner, at least initially, because there are always an odd number of cteni when they total no more than seven (i.e., 1 > 3 > 5 > 7). Following initial cteni formation, additional cteni are continually added laterally as small rudiments at each end of the row (Vaillant, 1875; Mookerjee, 1948; this study). Based on the work of Takagi (1953), Hughes (1981) suggested that in gobiids the spines comprise a single row of subcteni, and it may be significant that the inward curving shape of many ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 93

Figure 25. SEM's ofperciform ctenoid scales with peripheral cteni. A, B) The tripterygiid Tripterygion tripteronotus (Risso), USNM 285359, 51 mm SL, bars = 0.5 mm or 0.1 mm. C, D) The gobiid Yongeichthys nebu/osus (ForssklU), USNM 263511, 53 mm SL, note rudimentary cteni at each end of the row, bars = I mm or 0.5 mm. E) The serranid Pseudanthias thornsoni (Fowler), USNM 88184, 115 mm SL, note primary and secondary spines, bar = 0.2 mm. F) The eleotridid E/eotris sp., USNM 256509, 80 mm SL, in oblique posterior view, note primary and secondary spines, bar = 0.1 mm. gobioid peripheral cteni is very similar to the asymmetrical shape of whole sub- cteni before they transform. Although tentative, this possible homology between whole subcteni and gobioid peripheral cteni provides a credible mechanism for peripheral cteni to be derived from the basal percomorph condition. However, it does not adequately explain the development of primary and secondary cteni. Some ctenoid scales in species with peripheral cteni exhibit a few usually in- complete rows of truncated cteni in the apical area (Fig. 26; Hoese and Gill, 1993) which appear to be the result of the older cteni transforming into submarginal remnants as described above for transforming ctenoid scales. These scales are, however, still classified as peripheral ctenoid because only part of the marginal row transforms. Truncated cteni medial to peripheral cteni, although uncommon, 94 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993

Figure 26. SEM's of perciform ctenoid scales with peripheral cteni and a few truncated cteni sub- marginally, bars = I mm or 0,1 mm. A, B) The percophid Bernbrops rnacrornrna Ginsburg, USNM 304347, 119 mm SL. C, D) The nototheniid Notothenia larseni Lonnberg, USNM 301716, 152 mm SL. have been found on some scales of the percoids Pseudochromis salvati (this study) and Labracinus cyciophthalmus (Hoese and Gill, 1993) which have primary and secondary truncated cteni as well as primary and secondary peripheral cteni, the gobioids Odontobutis obscura (Kobayasi, 1953; Hoese and Gill, 1993), Acantho- gobius jlavimanus (Takagi, 1953), the blennioids Forsterygion varium and Kar- alepis stewarti (this study), the trachinoid Bembrops macromma (Fig. 26A, B), and the notothenioids Notothenia larseni (Fig. 26C, D) and Paranotothenia an- gustata (this study). The presence of truncated cteni with peripheral cteni is sig- nificant because they indicate that transforming cteni and peripheral cteni of percomorphs are homologues, which has important phylogenetic implications (see below).

Spined Scale Distributions in the Teleostei The phyletic distributions of the main types of spined scales within the Teleostei are plotted in Figure 27. Cycloid scales are present in all the main teleost lineages, but spined scales also occur widely throughout most of the Teleostei, being absent only from the relatively small clades Osteoglossomorpha and Salmonoidei. Cre- nate scales occur in the Elepocephala; they are most abundant in elopomorphs and clupeomorphs with only scattered occurrences in Esocae and Ostariophysi, and in higher teleosts, in a few aulopiforms and acanthopterygians. Spinoid scales ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 95

Osteoglossomorpha

Teleostei Elopomorpha

Elopocephala Clupeomorpha

Esocae

Euteleostei Ostariophysi

Osmerae

Salmonoidei

Neoteleostei Stomiiformes

Aulopiformes

Myctophiformes Ctenosquamata

Polymixiidae Acanthomorpha

Paracanthopterygii

Acanthopterygii Atherinomorpha

Percomorpha Figure 27. Distribution of spined scales in the Te1eostei. X, crenate scales; e, spinoid scales; •. , whole ctenoid scales; ., peripheral ctenoid scales; D., transforming ctenoid scales; note cycloid scales arc present in all lineages. are widespread throughout the Euteleostei, being most abundant in ostariophy- sians and acanthomorphs; they appear to be absent from the Salmonoidei, and occur only on a few osmeroids, stomiiforms, aulopiforms, and myctophiforms. The greatest morphological diversity of spined scales occur in the Ostariophysi 96 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993 and Percomorpha, and the Percomorpha have by far the greatest number of taxa with spined scales. Whole ctenoid scales are only known from three species in two percomorph genera. Transforming ctenoid scales are found only in the Per- comorpha, where they are abundant in perciforms, scorpaeniforms, and pleuro- nectiforms. Peripheral ctenoid scales are restricted to the three phyletically sep- arate euteleostean lineages Ostariophysi, Paracanthopterygii, and Percomorpha, where they have almost certainly evolved independently. Evidence of non-homology of peripheral cteni of ostariophysians, paracan- thopterygians and percomorphs is found in the morphology of the cteni and their articulation with the body of the scale: cteni of Gonorynchus (Ostariophysi; An- otophysi) have complex interlocking bases and except for the middle ctenus are inward curving; distichodontids (Ostariophysi; Otophysi; Characiformes) have closely abutting cteni well separated from the scale; Aphredoderus (Paracanthop- terygii; Aphredoderidae) has cteni with knobby bases which do not interlock, and some articulate with large raised knobs on the scale body; percomorphs generally have peripheral cteni with expanded bases connected to the scale by uncalcified collagen fibers, and some taxa have peripheral cteni in the alternating configuration of large primary and small secondary cteni. Aulostomus (Aulostomiidae; Gaster- osteiformes), usually considered to be a percomorph (but see General Discussion below), has cteni that overlap basally, a configuration that differs from that of typical percomorph peripheral cteni and suggests non-homology. Stiassny (1986) identified parallel evolution in at least four different advanced character complexes of ostariophysians and the higher neoteleosts. Similar par- allels have been found in spined scales during the present study. Notable examples in phyletically distant euteleost taxa are shown by linear spinoid scales (certain characiforms, e.g., Ctenolucius; myctophiforms, e.g., Myctophum asperum; ac- anthopterygians, e.g., Holocentrus), and peripheral ctenoid scales (certain ostar- iophysians, paracanthopterygians, and percomorphs detailed above). Stiassny (1986) suggested that morphological parallels between the independent characters she investigated may be functionally correlated with the evolution of jaw protru- sibility. The function of spined scales is unknown. Rosen (1973, 1985) considered "ctenoid" (=spinoid + ctenoid) scales to be synapomorphic evidence, together with numerous other advanced characters, that myctophiforms are distinct from aulopiforms, and are the primitive sister group of acanthomorphs, which together form the higher neoteleost clade Ctenosqua- mata. However, the results of the present study show that spinoid scales occur in a few aulopiforms, and both spinoid and ctenoid scales occur in some lower euteleosts (Fig. 27), questioning the validity of this character at the ctenoquamate level, as noted by Johnson, R. K. (1982, 69) and Johnson, G. D. (1992, 13). The synapomorphic validity of spinoid + ctenoid scales is further clouded by probable convergent evolution in separate euteleostean lineages coupled with probable non- homology of the spiny scale structures. To argue that spinoid + ctenoid scales is synapomorphic for the Euteleostei, is to also argue that the character has been independently lost many times in the large majority of taxa in each main euteleos- tean lineage. It is more parsimonious to argue that spinoid scales and (peripheral) ctenoid scales have evolved independently several times in euteleosts, an argument supported by morphological differences (reflecting probable non-homology) among spine types. Nevertheless, the similarity among probably analogous spinoid scales and the similarity among probably analogous peripheral ctenoid scales are re- markable and are classic examples of convergent character evolution. ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 97

GENERAL DISCUSSION Hughes (1981) described the formation, development, and resorption of cteni in the percomorph scorpaenid family Platycephalidae. She concluded that the development of the posterior field is such that the addition of a new row of cteni involves a maximum of only 50% of the scale margin and that, as the ctenus spine degenerates, it is effectively replaced by a new ctenus. Hughes postulated two advantages for this type of development: (1) if only 50% of the scale margin is growing, the (unknown) function of fully formed cteni is not impeded, and (2) the spinal degeneration of older cteni when new cteni develop behind them is a mechanism for conserving and recycling scale material. Thus, the evolution of transforming cteni can be interpreted as a unique specialization, a synapomorphy supporting the hypothesis of a monophyletic Percomorpha. Unlike the more inclusive Percomorpha of previous authors (Lauder and Liem, 1983), the Percomorpha sensu Roberts, defined by the synapomorphic character transforming cteni, comprises only the three orders: Scorpaeniformes, Pleuro- nectiformes and Perciformes. If the Pleuronectiformes and Scorpaeniformes are accepted as monophyletic (Hensley and Ahlstrom, 1984; Washington et aI., 1984), then those pleuronectiform and scorpaeniform taxa without scales, or with cycloid, pseudocycloid (Hughes, 1981), spinoid or peripheral ctenoid scales, are not ex- cluded from the Percomorpha. The same does not apply to the Perciformes, for which there is no evidence of monophyly. Some, perhaps many, taxa currently considered to be perciforms that do not possess scales with transforming cteni, may have diverged below the percomorph clade. Two previously problematic acanthomorph taxa, Mugiloidei and Polynemoidei, have transforming ctenoid scales. The phylogenetic position of both suborders has been controversial (Nelson, J., 1984,323-325; Stiassny, 1990), but their trans- forming cteni (Appendix I) is here considered strong evidence that they are per- comorphs. Cycloid, crenate, or whole ctenoid scales of some mugiloids are in- terpreted as secondary. The strict interpretation of the Percomorpha proposed here excludes the par- acanthopterygian Aphredoderoidei and Percopsidae, the acanthopterygian Ath- erinomorpha, and the following taxa previously classified as percomorphs: Lam- priformes, Gasterosteiformes, Pegasiformes, Dactylopteriformes, Beryciformes, Zeiformes, Tetraodontiformes, Channiformes (but submarginal ornamentation described by Haque, 1955, and not seen by me may prove to be modified truncated cteni), Synbranchiformes (hypothesized by Lauder and Liem, 1983, to be the sister group ofChanniformes), Mastacembeloidei, Polymixiidae, Bramidae, How- ellidae, Rosenblattia, Epigonidae, Ostracoberycidae, Priacanthidae, Pomacanthi- dae, and Pomatomidae. It should be possible to corroborate or refute this hy- pothesis by cladistic analysis of other character complexes. Although monophyly of the Percomorpha sensu Roberts is supported by one synapomorphy, problems remain in defining its limits due to possible loss or reversal of transforming cteni. Currently, the only way to identify taxa that lack transforming cteni as percomorphs is by parsimony argument, where adequate phylogenetic data exist. In the Labroidei, for example, a corroborated hypothesis of relationship of the families has been presented (Kaufman and Liem, 1982; Lauder and Liem, 1983, fig. 52; Stiassny and Jensen, 1987). Members ofthe two basal families Pomacentridae and Cichlidae possess transforming cteni, whereas the derived families Embiotocidae and Labridae possess cycloid scales (Appendix 1). It is more parsimonious to consider that transforming cteni have been lost by 98 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993

embiotocids and labrids, rather than remove them from the Percomorpha, and propose that the severallabroid synapomorphies that they possess have evolved independently. This argument applies equally to percomorph clades containing taxa without scales or with cycloid, crenate or spinoid scales (e.g., Scombroidei by Johnson, 1986; Acanthuroidei by Tyler et aI., 1989; Trachinoidei by Pietsch, 1989; Pietsch and Zabetian, 1990), and to those with peripheral cteni. Most gobioids have scales which are either cycloid or peripheral ctenoid, com- prising either primary cteni or primary and secondary cteni. That gobioids are percomorphs is shown by the scales of Rhyacichthys aspro (monotypic family Rhyacichthyidae) which is the sister-group of all other gobioids (Miller, 1973; Springer, 1983; Birdsong et aI., 1988; Hoese and Gill, 1993). Body scales of R. aspro have transforming cteni in the form of a single row of modified marginal whole cteni (not in two alternating rows which is the generalized percomorph condition) and several rows of truncated bases (this study; Miller, 1973, pI. 1). The percomorph relationship of gobioids is further supported by the observed occurrence of incomplete rows of transforming cteni in some scales of certain gobiids (see Peripheral cteni section above). Springer (1983, 36) recognized the primitive character of "multiseriate cteni" on the scales of R. aspro, and noted that "gobioid scales appear to be specialized in that only the ... peripheral ctenii may be teeth-like; the others are cuboidal ... a few may exhibit two or three rows of ctenii, by far the majority have none or only one row." Another example of reduction of the rows of truncated bases and modification of the marginal cteni can be seen in the monophyletic basal percomorph family Serranidae (Johnson, 1983). The generalized percomorph scale is found in Epi- nephelus (Fig. 21D), which has rows of truncated cteni filling the broad posterior field. In the serranid subfamily Anthiinae a progressive reduction of the rows of truncated bases is apparent. In basal anthiine genera, e.g., Caesioperca, Caprodon and Lepidoperca (Roberts, 1989), there are only about three rows of truncated cteni, whereas in more advanced anthiine genera such as Pseudanthias (Fig. 25E), Anthias and Holanthias, there is a complete loss of truncated cteni, and modifi- cation of the marginal cteni into primary and secondary cteni (Appendix 1). The presence of peripheral primary and secondary cteni and absence of truncated cteni on the scales of the anthiine originally known as Caesioperca thomsoni Fowler (together with other specializations) support its placement in another genus, prob- ably Pseudanthias. The development of peripheral primary and secondary cteni is complex and not well understood, but may occur through modification of the basal percomorph ctenial growth process. Figure 28 illustrates steps in the development and growth ofa new row of basal percomorph cteni, and the coincident transformation of the old inner row of cteni. If early development ceases before the second row has fully formed and, therefore, before a row of truncated cteni has formed, then the relative size, shape and configuration of the cteni is very similar to, and possibly homologous with, that of peripheral cteni in the distinctive primary and secondary pattern. Further modification is seen in some pseudochromids that have primary and secondary cteni transforming into primary and secondary truncated cteni submarginally. The fact that the distinctive pattern of primary and secondary cteni is found in phyletically distant percomorph taxa (Appendix 1) suggests that it has evolved separately through similar modifications of the basal percomorph ctenial growth process. The absence of primary and secondary cteni outside the Percomorpha in paracanthopterygian and ostariophysian taxa, which have pe- ripheral cteni but do not exhibit transforming ctenoid ontogeny, lends support to this interpretation. ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 99

1

2

3

o 4

Figure 28. Diagram showing growth of cteni in transforming ctenoid scales. Note halting of ctenial growth at step 2 before the second row has fully developed, coupled with lateral rather than posterior growth, may produce the configuration of alternating primary and secondary peripheral cteni. Step 1: A marginal row of cteni. Step 2: A new distal row of cteni forming. Step 3: Distal row of cteni fully formed. Step 4: New distal row of cteni forming and old proximal row degenerated into base and truncated spine.

Although ontogenetic evidence of relationship between transforming and pe- ripheral ctenoid scales is currently limited, evidence from both ontogenetic studies of scale development and juvenile structures retained in adult scales suggest that crenate, spinoid and ctenoid scales each develop from a generalized cycloid state. At the percomorph level, however, transforming ctenoid scales are generalized, while cycloid, crenate and spinoid scales are derived. These apparent polarity reversals are probably attributable to changes in ontogenetic trajectories that result in the retention ofplesiomorphic terminal character states. Judging by the frequent occurrence of cycloid, crenate and spinoid scales in percomorphs (Appendix 1), ontogenetic modifications as well as evolution of new characters have probably occurred widely and independently during percomorph scale evolution. Accord- ingly, an understanding of heterochronic ontogeny in relation to phylogeny will 100 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993 be necessary to help establish polarity of the scale types of many percomorphs, and this will clearly be a fruitful area for future research, We are only just beginning to learn about the types of micro- and macro- structures present in fish scales, the processes that are responsible for their de- velopment and growth, and the processes that have contributed to their evolution. Like all previous lepidologists who have studied in detail the morphology of a wide range of scale types, I have been impressed by the great diversity of scale structures exhibited, and the seemingly endless variations on each morphological theme, particularly among the percomorphs. In this paper I have attempted to summarize this diversity and show at least some of the potential value of com- parative morphology of spined scales when analyzed in a phylogenetic context. Ifmy paper stimulates further scale studies, particularly those addressing polarity and ontogeny of scale characters, I predict that they will make a significant con- tribution towards obtaining a better understanding of percomorph and teleost evolution.

ACKNOWLEDGMENTS

The following individuals contributed to the study by generously providing curatorial assistance, technical help, sound advice, stimulating discussion, and many other courtesies: J. A. F. Garrick, P. H. J. Castle (VUW), P. H. Greenwood (BMNH & RUSI), R. R. Carthy, J. M. Clayton, B. B. Collette, R. E. Gibbons, J. C. Harshbarger, W. F. Hoffman, S. L. Jewett, G. D. Johnson, L. W. Knapp, T. A. Munroe, M. S. Nizinski, T. Orrell, L. F. Palmer, L. R. Parenti, K. L. Price, S. J. Raredon, M. Rauchenberger, D. J. Siebert, V. G. Springer, W. C. Starnes, R. P. Vari, M. Weitzman, S. H. Weitzman, J. T. Williams (USNM), R. M. C. Castro (Universidade de Sao Paulo, Brazil), B. A. Marshall, C. D. Paulin, and A. L. Stewart (NMNZ). I thank W. R. Brown, S. G. Braden, B. E. Kahn (SEM Laboratory, USNM), R. W. Thomson, and K. Goldie (EM Facility, School of Biological Sciences, VUW) for their patient and skilled help with SEM work; M. Angelo and S. Superville (Hector Library, NMNZ) for help with literature; and A. Van Heiden (NMNZ) for translations. This study was carried out during tenure of a Leverhulme Trust Fund U.K. Overseas Scholarship and a Jacob Joseph Scholarship at Victoria University of Wellington, during a Postdoctoral Fellowship at the Smithsonian Institution, Washington, D. C., U.S.A., and completed at the National Museum of New Zealand (now the Museum of New Zealand Te Papa Tongarewa), Wellington. Special thanks are given to G. D. Johnson for support, advice, and encouragement during my fellowship year at the Smithsonian Institution, and to R. P. Vari for presenting my paper at the Percomorph Phylogeny Symposium. The paper benefited from critical reviews given by W. D. Anderson, Jr., A. C. Gill, A. S. Harold, G. D. Johnson, and R. Mooi.

LITERATURE CITED

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DATEACCEPTED: July 6, 1992.

ADDRESSES:Division of Fishes, Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, Washington D. C. 20560; PRESENTADDRESS:Department of Natural Environment. Museum of New Zealand Te Papa Tongarewa, P.O. Box 467, Wellington, New Zealand.

Appendix I. List of fish species whose scales were sampled, method of scale preparation and scale types found; note more than one type of body scale may be present. Scale preparation abbreviations: LM, detailed examination of cleaned and alizarin stained scales under light microscope; SM, detailed examination of cleaned and gold coated scales under scanning electron microscope; U, examination of unprocessed scales under light microscope. Scale type abbreviations: Cy, cycloid; Cr, crenate; Sp, spinoid; Wh, whole ctenoid; Tr, transforming ctenoid; Pe, peripheral ctenoid; +, alternating primary and secondary ctenoid. Specimen catalog details are deposited in the Fish Section library (USNM) and the Hector Library (NMNZ)

Scale preparation Scaletype Teleostei Osteoglossomorpha Osteoglossoidei Arapaima gigas LM,SM Cy Osteoglossum bieirrhosum LM,SM Cy Pantodon buchholzi LM,SM Cy Scleropages jardini LM,SM Cy Notopteroidei Hiodon alosoides LM,SM Cy Notopterus sp. LM,SM Cy Mormyrus longirostris LM,SM Cy Elopomorpha Elopidae Elops saurus LM,SM Cr Megalopidae Megalops atlantica LM,SM Cr Albuloidei Albula vulpes LM,SM Cr Halosaurus sp. LM,SM Cy Halosaurus pectoralis U Cy Halosauropsis macrochir U Cy Notocanthus chemnitzi LM,SM Cy Notocanthus sexspinnus U Cy Polyacanthonotus rissoanus U Cy Pterothrissus bel/oei LM,SM Cy 106 BULLETIN OF MARINE SCIENCE, VOL. 52, NO, I, 1993

Appendix I, Continued

Anguilloidei Anguilla rostrata LM,SM Cy Clupeomorpha Denticipitoidei Denticeps clupeoides LM,SM Cy Clupeoidei Chirocentrus dorab LM,SM Cr Clupea pilchardus LM,SM Cy Dussumieria acuta LM,SM Cy Engrau/is dussumieri LM,SM Cy Esocae Esox americanus LM,SM Cr Umbra krameri LM,SM Cy Ostariophysi Anotophysi Chanos chanos LM,SM Cy Gonorynchus gonorynchus LM,SM Pe Kneria sp. LM,SM Cy Phractolaemus ansorgei LM,SM Cy Otophysi Cypriniformes Ba/itropsis bartschi LM,SM Cy Catastomus catostomus LM,SM Cy Cirrhina reba LM,SM Cr Cyprinus carpio LM,SM Cy Myxocyprinus asiaticus LM,SM Cy Tor putitora LM,SM Cy Characiformcs Ctenobrycon spilurus U Sp, Cy Ctenolucius beani LM,SM Sp Distichodus rostratus LM,SM Pc Euganathichthys eetveldtii LM,SM Pc Galeocharax gulo LM,SM Sp Phago loricatus LM,SM Pc Potamorhina pristigaster LM,SM Sp Prochilodus mariae LM Sp Prochilodus nigricans LM,SM Sp Semaprochilodus insignis LM Cy Gymnotoidei Gyrnnotus carapo LM,SM Cy

Osmcrac Argentinoidci Argentina silus LM,SM Sp Argentina sphyraena LM,SM Sp,Cy Osmeroidei Prototroctes oxyrhynchus U Cy Retropinna retropinna LM,SM Cy Salmonoidei Coregonus clupeajormis LM,SM Cy Oncorhynchus mykiss LM,SM Cy Salmo trutta LM,SM Cy Neoteleostei Stomiiformes Chau/iodus danae U Cy Chau/iodus sloani U Cy Diplophos taenia LM,SM Cy Polyipnus tridentifer U Sp,Cy ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 107

Appendix I. Continued

Stomias affinis U Cy Stomias co/ubrinus U Cy Aulopiformes Aulopoidei Au/opus japonicus LM,SM Sp,Cy Au/opus nanae U Sp,Cy Aulopus purpurissatus U Sp,Cy Bathypterois quadrifilis LM,SM Cr Ch/orophthalmus agassizi U Cr Chlorophthalmus brasiliensis LM,SM Cr Chlorophthalmus nigripinnis SM Cy Parasudis truculent us LM,SM Cr Alepisauroidei Para/epis coregonoides LM,SM Sp Myctophiformes Myctophidae Lampanyctodes australis SM Cy Myctophum affine U Sp Myctophum asperum LM,SM Sp Myctophum selenops LM,SM Sp Notoscope/us japonicum LM,SM Sp N eoscopelidae Soli vomer arenidens LM,SM Sp Polymixiida Polymixia /owei LM,SM Sp Paracanthopterygii Percopsiformes Aphredoderus sayanus LM,SM Pc Percopsis omiscomaycus LM,SM Sp Gadiformes Gadus macrocephalus LM,SM Cy Macrourus carinatus SM Sp Mora moro SM Cy Pseudophycis bach us LM Cy Ophidiiformes Brotula barbata SM Cy Neobythites sp. SM Cy Ophidion holbrooki SM Cy Batrachoidiformes Batrachoides surinamensis SM Cy Atherinomorpha Atheriniformes Atherina hepsetia SM Cy Hypoatherina /acunosa SM Cy Cyprinodontiformes Lamprichthys tanganicanus LM,SM Cy Poecilia /atipinna LM,SM Cy Poeciliopsis inJans LM,SM Cy Poeciliopsis turrubarensis LM,SM Cy Xenodexia cteno/epis LM,SM Sp Beloniformes Exocoetus obtusirostris SM Cy Hemiramphus Jar LM,SM Cy Scomberesox saurus LM,SM Cy Percomorpha sensu lato Lampridiformes Ve/ifer aJricanus LM,SM Cy 108 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993

Appendix I. Continued

Gasterosteiformes Aulostomus maculatus LM,SM Pe Dactylopteriformes Dactylopterus volitans LM,SM Sp Zeiformes Antigoniidae Antigonia capros LM,SM Sp Capros aper LM,SM Sp Grammicolepididae Grammicolepis brachiusculus U Sp Xenolepidichthys dalgleishi U Sp Oreosomatidae Allocytus verrucosus U Sp Neocyttus rhomboida/is U Sp Neocyttus sp. SM Sp Zeidae Cyttopsis roseus U Cy Cyttus australis SM Sp Zeus faber LM,SM Cy Zeniontidae Zenion leptolepis U Sp Incertae sedis Capromimus abbreviatus U Sp Beryciformes Berycoidei Beryx splendens SM Sp Centroberyx affinis SM Sp Flammeo sam mara U Sp H oplostethus mediterraneus SM Sp Myripristis kunti U Sp Paratrachichthys trailli SM Sp Plectrypops sp. U Sp Sargocentron diadema LM,SM Sp Sargocentron spiniferum U Sp Stephanoberycoidei Stephanoberyx monae LM,SM Sp Perciformes Percoidei Acropomatidae Doederleinia berycoides LM,SM Tr Apogonidae Apogon kallopterus U Tr Apogon novemfasciatus U Tr Archamia leai U Tr Cheilodipterus quinquelineatus U Tr Arripidae Arripis trutta LM,SM Tr Bramidae Brama brama LM,SM Sp Caesionidae Caesio caerulaurea U Tr Callanthiidae Callanthias australis U Pe+ Carangidae Elagatis bipinnulatus SM Cr Naucrates ductor SM Cr Centrarchidae Amblop/ites rupestris U Tr Archoplites interruptus U Tr Lepomis macrochirus SM Tr ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 109

Appendix I. Continued

Centropomidae Lates ealearifer SM Tr Elassomatidae Elassoma zonatum SM Cy Emmelichthyidae Emmeliehthy nitidus LM Tr Plagiogeneion rubiginosus U Tr Ephippididae Ephippus orbis SM Sp Epigonidae Epigonus lenimen U Wh Epigonus teleseopus SM,U Wh Howellidae Howella brodiei U Sp Kuhliidae Kuhlia mugil U Tr Kyphosidae Atypiehthys latus U Tr Girella eyanea U Tr Lethrinidae Lethrinus genivittatus U Tr Gnathodentex aurolineatus U Tr Lutjanidae Lutjanus russelli U Tr Pristipomoides sp. U Tr Moronidae Lateolabrax japonieus LM,SM Tr Morone americana LM,SM Tr Morone labrax SM Tr Morone saxatilis SM Tr Nemipteridae Seolopsis bi/ineatus U Tr Ostracoberycidae Ostraeoberyx dorygenys SM Sp Pempheridae Pempheris adspersus U Tr Percichthyidae Maeeulloehella maequariensis SM Tr Maequaria australasiea SM Tr Perealates novemeinetus SM Tr Perciehlhys trueha SM Tr Pleetroplites ambiguus SM Tr Percidae Etheostoma sp. U Tr Perea flaveseens LM,SM Tr Perea fluviatilis U Tr Stizostedion sp. U Tr Plesiopidae Aeanthoclinus fuseus LM Cy Plesiops insularis U Tr, Cy Plesiops vereeundus U Tr Polyprionidae Polyprion amerieanus LM,SM Tr Polyprion oxygeneios LM,SM Tr Stereolepis gigas LM,SM Tr Pomacanthidae Pomaeanthus semicireulatus SM Sp Pomatomidae Pomatomus sallatrix SM Sp 110 BULLETIN OF MARINE SCIENCE, VOL. 52, NO. I, 1993

Appendix 1. Continued

Priacanthidae Cookeolus japonicus SM Sp Heteropriacanthus cruentatus SM Sp Priacanthus macracanthus SM Sp Priacanthustayenus SM Sp Pristigenys meyeri SM Sp Pristigenys serrula SM Sp Pseudochrom idae Pseudochromis jamesi U Tr Pseudochromis salvati U Pe+ Scatophagidae Scatophagus argus SM Sp Sciaenidae Micropogon undulatus SM Tr Scombrolabracidae Scombrolabrax heterolepis SM Cy Serranidae Aporops sp. U Tr, Cy Acanthistius cinctus U Tr Anthias anthias SM Pe+ Aulacocephalus temmincki U Tr Caprodon longimanus U Tr Caesioperca lepidoptera U Tr Cephalopholis argus U Tr Epinephelus daemelii SM Tr Epinephelus nigritus LM,SM Tr Epinephelus octofasciatus LM Tr Grammistes sexlineatus SM Cy Holanthias sp. U Pe+ Hypoplectrodes huntii U Tr Lepidoperca aurantia U Tr Lepidoperca coatsii LM,SM Tr Lepidoperca inornata U Tr Plectranthias kelloggi U Tr Plectranthias longimanus U Pe Plectranthias maculicauda U Tr Pseudanthias pictilis LM,SM Pe+ Pseudanthias thompsoni LM,SM Pe+ Pseudogramma polyacantha U Tr, Cy Serranus cabrilla U Tr Serranus novemcinctus SM Tr Trachypoma macracanthus U Tr Sinipercidae Coreoperca kawamebari LM,SM Cy Siniperca chuatsi SM Cy Sparidae Pagrus auratus LM Tr I ncertae sedis Rosenb/atlia robusta U Sp Labroidei Pomacentridae Chromis hypsilepis SM Tr Pomacentrus philippinus SM Tr Cichlidae Cichla ocellaris LM,SM Tr Embiotocidae E mbiotoca jacksoni SM Cy Labridae Noto/abrus celidotus SM Cy Pseudolabrus miles SM Cy ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES III

Appendix I. Continued

Acanthuroidei Acanthuridae Acanthurus lineatus LM,SM Tr Ctenochaetus binotatus LM,SM Tr Naso lituratus U Sp Zebrasoma veliferum U Sp Siganidae Siganus corallin us SM Cy Zanclidae Zanclus comUlus U Sp Blennioidei C1inidae Clinus superciliosus LM,SM Cy Cologrammus j/avescens LM Cy Ericentrus rubrus LM Cy Dactyloscopidae Dactyloscopus zelotus SM Cy Tripterygiidae Bellapiscis medius U Pe Forsterygion varium LM Pe Gilloblennius tripennis U Pe Kara/epis stewarti U Pc Notoclinops segmentatus LM Pc Ruanoho decemdigitatus U Pc Tripterygion tripteronotus LM,SM Pc Zoarcoidci Bothrocara brunneum SM Cy Emogrammus enneagrammus SM Cy Zaprora silenus SM Cy Notothcnioidci Notothenia coriiceps U Tr Notothenia /arseni LM,SM Pe Paranotothenia angustata U Pc Trachinoidci Acathaphrites grandisquamis U Cr Bembrops filifera LM,SM Pe Bembrops macromma LM,SM Pc Champsodon sp. LM,SM Sp Chrionema chryseres U Pc+ Cheimarrichthys Josteri LM,SM Tr Hemerocoetes monpterygius SM Cy Parapercis clathrata LM,SM Tr Gobioidei Eleotrididae Eleotris sp. LM,SM Pc+ Eleotris Jusca U Pe+ Gobiomorphus breviceps U Pc Gobiomorphus basalis U Pc Gobiomorus maculatus LM,SM Pc Ophie/eotris aporos U Pc Thalasseleotris sp. U Pc Gobiidac Asterropteryx semipunctatus U Pc Coryphopterus nicho/si U Pc Favonigobius lentiginosus U Pc Gobiopsis atrata U Cy Yongeichthys nebulosus SM Pc Rhyacichthyidae Rhyacichthys aspro SM Tr 112 BULLETIN OF MARINE SCIENCE, VOL 52, NO. I, L 993

Appendix I. Continued

Scombroidei Sphyraenidae Sphyraena barracuda SM Cy Gempylidae Ruvettus pretiosus LM,SM Sp,Cy Scombridae Gasterochisma melampus SM Cy Scomber scombrus SM Cy Mastacembeloidei Mastacembelus erthrotaenia LM,SM Cy Polynemoidei Polynemus plebeus LM,SM Tr Mugiloidei Aldrichetta forsteri U Tr, Cy Cestraeus goldiei U Tr Chelon sp. SM Tr Crenimugil crenilabis U Cy Joturus pechardi LM,SM Tr Mugil cephalus LM,SM Wh Myxus capensis U Tr, Cy Myxus elongatus U Tr, Cy Neomyxus chaptalii U Cy Valamugil seheli U Cr Anabantoidei Anabas testudineus LM,SM Tr Be/ontia hasse/Iii LM,SM Tr He/oslOma temminckii LM,SM Tr Luciocephalus pulcher LM,SM Tr Osphronemus goramy LM,SM Tr Scorpaeniformes Anoplopomatidae Anoplopoma fimbria SM Tr Hexagrammidae Hexagrammus hexagrammus SM Tr Scorpaenidae Dendrochirus biocellatus U Tr Ebosia bleekeri SM Sp,Cy Helicolenus percoides LM Tr Maxi/licosta raou/ensis U Sp,Cy Notesthes robusta U Tr Parapterois heterurus SM Sp Scorpaena a/bodrunnea U Tr Scorpaena cardinalis LM,SM Tr Scorpaena cookii U Tr Scorpaena guamensis U Tr Scorpaena sp. U Pe Scorpaenodes kelloggi U Tr Scorpaenopsis diabo/us U Tr Sebastes marinus SM Tr Setarches longimanus U Cy Channiformes Channa gachua LM,SM Cy Tetraodontiformes Monacanthidae Parika scaber LM,SM Sp Triacanthidae Tripodichthys blochii LM,SM Sp Pleuronectiformes Psettodoidei Psettodes be/cheri LM,SM Tr ROBERTS: PHYLOGENETIC SIGNIFICANCE OF SPINED SCALES 113

Appendix 1. Continued

Pleuronectoidei Bothidae Achiropsetla tricho/epis SM Sp Achiropsetta sp. SM Sp Arnog/ossus scapha LM Tr Bothus constel/atus U Tr Bothus mancus U Tr Bothus pantherinus U Tr Crossorhombus azureus U Pe Lophonectes gal/us U Tr Neoachiropsetla milfordi SM Tr Paralichthys /ethostigma LM,SM Cy Pseudorhombus jenynsii U Tr Citharidae Citharus macro/epidotus LM,SM Tr Pleuronectidae Atheresthes stomias U Tr Azygopus pinnifasciatus U Tr Colistium guntheri U Tr Co/istium nudipinnis U Tr Parophrys vetu/us U Cy Pe/ortretis j1avi/atus LM Tr Pe/torhamphus latus U Tr Pe/tohamphus novaezee/andiae U Tr Rhomboso/ea /eporina U Cy Rhomboso/ea p/ebia LM Cy Samariscus triocel/atus U Tr Soleoidei Soleidae Pardachirus marmoratus U Tr Cynoglossidae Symphurus p/agusia U Tr Symphums tessel/atus LM,SM Tr