Teleostei: Perciformes: Leiognathidae): Phylogeny, Taxonomy, and Description of a New Species

Home , Gazza (fish), Gazza minuta, Leiognathidae, Leiognathus, Leiognathus equulus, Secutor (fish)

CORE Metadata, citation and similar papers at core.ac.uk

Provided by American Museum of Natural History Scientific Publications

PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024 Number 3459, 21 pp., 8 ®gures, 2 tables October 28, 2004

A Clade of Non-Sexually Dimorphic Pony®shes (Teleostei: Perciformes: Leiognathidae): Phylogeny, Taxonomy, and Description of a New Species

JOHN S. SPARKS1 AND PAUL V. DUNLAP 2

ABSTRACT A phylogeny was generated for Leiognathidae, commonly known as pony®shes, using nucleotide characters from two mitochondrial genes. Results indicate that Leiognathidae comprises two major clades, one consisting of species that exhibit internally sexually dimorphic light-organ systems (LOS), and the Leiognathus equulus species complex, whose members exhibit neither internal nor external sexual dimorphism of the LOS. Species with internally sexually dimorphic LOS generally also exhibit associated male-speci®c external modi®cations in the form of transparent patches on the margin of the opercle, the midlateral ¯ank, or behind the pectoral ®n axil. The L. equulus species complex is the sister group to all other leiognathids, and a new species, L. robustus, recovered within this clade is described herein. Results demonstrate that Leiognathus is paraphyletic, whereas Gazza and Secutor are each monophyletic and are nested within the sexually dimorphic clade. The morphology of the LOS of non- sexually dimorphic leiognathids is compared to the more common sexually dimorphic state, and differences in these systems are discussed and illustrated. In the context of a family-level phylogeny, we can trace the evolution of the leiognathid LOS from a ``simple'' non-sexually dimorphic circumesophageal light organ to a complex and species-speci®c luminescence system involving not only major structural modi®cations of the light organ itself but also numerous associated tissues.

1 Department of Ichthyology, Division of Vertebrate Zoology, American Museum of Natural History ([email protected]). 2 Department of Ecology and Evolutionary Biology, University of Michigan, 830 North University Ave., Ann Arbor, MI 48109 ([email protected]). Copyright ᭧ American Museum of Natural History 2004 ISSN 0003-0082 2 AMERICAN MUSEUM NOVITATES NO. 3459

INTRODUCTION dimorphic and sexually dimorphic clades that were recovered in this analysis. Together Leiognathids, commonly known as pony- with a morphological analysis of the light or- ®shes or slipmouths, are bioluminescent, gan and associated tissues of the LOS in the schooling ®shes common in near-shore and nondimorphic clade, we describe a new spe- estuarine Indo-Paci®c waters from the east cies of leiognathid bearing a non-sexually di- coast of Africa to islands of the west Paci®c morphic light organ. In the context of the and from Japan to Australia. As locally abun- recovered phylogeny, we discuss the insights dant ®shes in turbid coastal waters, they of- this nondimorphic clade provides into the ten are captured in mixed assemblages of a evolution and diversi®cation of the leiog- few to several species (McFall-Ngai and nathid LOS. Further, taxonomic and nomen- Dunlap, 1984; Woodland et al., 2001; P.V. clatural implications (i.e., paraphyly of Dunlap, personal obs.). Approximately 40 Leiognathus) are discussed in light of the re- species in three genera, Gazza, Leiognathus, covered phylogenetic pattern. and Secutor, are currently recognized (Esch- meyer, 1998; Froese and Pauly, 2003; Wood- land et al., 2001). MATERIALS AND METHODS Luminescence in leiognathids is produced MORPHOLOGY from an internal light organ, a circumesophageal ring of tissue in which are harbored Osteological characters of the new species large numbers of the symbiotic luminous and related taxa were examined using radio- bacterium, Photobacterium leiognathi (Bois- graphs, specimens cleared and stained for vert et al., 1967; Hastings and Mitchell, bone and cartilage, and dry skeletal prepa- 1971; Bassot, 1975; Reichelt et al., 1977; rations. Materials examined are listed in ap- Dunlap, 1984). Together with the light organ, pendix 1. When suf®cient material was avail- the light-organ system (LOS) of leiognathids able, multiple males and females of each spe- is composed of re¯ectors and chromato- cies were dissected and examined for LOS phore-embedded light-organ shutters, trans- features. Light organs were isolated from parent and re¯ective tissues of the gasblad- each taxon to permit detailed comparison. der, and transparent bone, musculature, and Specimens were cleared and stained for bone skin (®g. 1). These accessory tissues function and cartilage using a modi®ed protocol based to control, direct, and diffuse the intense on Taylor and Van Dyke (1985). Morpho- blue-green bacterial light over the ventral metric measurements were recorded to the surface of the ®sh (Harms, 1928; Ahrens, nearest 0.1 mm using dial calipers. Standard 1965; Bassot, 1975; McFall-Ngai, 1983; length (SL) is used throughout. Body depth McFall-Ngai and Dunlap, 1983; Dunlap and A was measured at a vertical from the origin McFall-Ngai, 1987). Hypothesized functions of the anal ®n, and body depth B at a vertical of the bacterial light include camou¯age il- from the origin of the dorsal ®n. Vertebral lumination against bottom-dwelling piscivo- counts exclude the ural centrum (ϭ last half- rous ®shes and other forms of predator centrum). Vertebral and ®n spine/ray counts avoidance, prey attraction, schooling, and were obtained from radiographs. The termi- sex-speci®c signaling (Hastings, 1971; Her- nal dorsal-®n and anal-®n rays, which are ring and Morin, 1978; McFall-Ngai, 1983; branched to the base of the ®n, are counted McFall-Ngai and Dunlap, 1983, 1984; Dun- as a single element. Pored scales of the lat- lap and McFall-Ngai, 1987; McFall-Ngai and eral line are counted in series from the dorsal Morin, 1991; Woodland et al., 2002). margin of the gill opening to the caudal ¯ex- In the present study, to gain a more de- ure. Scale counts should be interpreted as ap- tailed understanding regarding evolution of proximations, due to high intra- and inter- the LOS in pony®shes, we generated a phy- speci®c variability, irregular arrangement, logeny for the family based on nucleotide and because small scale size and the degree characters from two mitochondrial genes. In to which scales are embedded make accurate addition, we examined numerous museum counts problematic. Institutional abbrevia- lots of specimens belonging to both the non- tions follow Leviton et al. (1985). 2004 SPARKS AND DUNLAP: NON-SEXUALLY DIMORPHIC PONYFISHES 3

Fig. 1. Comparison of light organs (circled) and associated features of the LOS in male leiognathids exhibiting both sexually dimorphic and nondimorphic states. Leiognathus elongatus, extreme sexual dimorphism: (A) external anatomy illustrating expansive transparent lateral ¯ank patch characteristic of males, which is located just external to the clear gasbladder wall and enlarged dorsal lobes of the male light organ; (B) internal anatomy illustrating lateral clearing of the silvery gasbladder lining (arrow) and hypertrophied dorsal lobes of the light organ, which lie internal to the gasbladder lining (removed). Leiognathus aureus, moderate to extreme sexual dimorphism: (C) external anatomy illustrating transparent pectoral-axil patch characteristic of males, which lies just exterior to the hypertrophied dorsolateral light-organ lobes; (D) internal anatomy illustrating enlarged dorsolateral light-organ lobes that abut lateral clearing of the integument just internal to the pectoral-®n axil. Leiognathus equulus, nondimorphic: (E) external anatomy; (F) internal anatomy. In members of the L. equulus species complex the light organ is not enlarged in males and there is no corresponding lateral clearing of the silvery gasbladder lining (arrow indicates posterior clear region common to all leiognathids) or integument proximal to the light organ. 4 AMERICAN MUSEUM NOVITATES NO. 3459

TABLE 1 Taxa Used in Molecular Phylogenetic Analysis, Including Collection Locality, Tissue Voucher Code, and GenBank Accession Numbers

INSTITUTIONAL ABBREVIATIONS DNA SEQUENCING AND SEQUENCE ANALYSIS AMNH American Museum of Natural History, A total of 1251 nucleotide characters from New York two mitochondrial genes (the large ribosomal AMS Australian Museum, Sydney subunit [16S] and cytochrome c oxidase sub- BMNH Natural History Museum, London unit I [COI]) were used in the phylogenetic CAS California Academy of Sciences, San Francisco analysis. Taxon sampling was designed to in- LACM Los Angeles County Museum of Nat- clude a diverse assemblage of leiognathid ural History species representative of overall familial di- SIO Scripps Institution of Oceanography, versity (table 1 and appendix 1). In addition Marine Vertebrates Collection, La Jolla to all leiognathid species included in the mo- UMMZ University of Michigan, Museum of lecular analysis, a number of species for Zoology, Ann Arbor which tissue samples suitable for molecular USNM National Museum of Natural History, studies could not be obtained were examined Smithsonian Institution, Washington, for LOS features. Outgroup taxa were se- D.C. ZMB Universitat Humboldt, Museum fur Na- lected from perciform families hypothesized turkunde, Berlin to be closely related to leiognathids, includ- ZMUC Kobenhavns Universitet, Zoologisk ing members of Gerreidae (mojarras) and Museum, Copenhagen Carangidae (jacks) (GuÈnther 1862; Weber 2004 SPARKS AND DUNLAP: NON-SEXUALLY DIMORPHIC PONYFISHES 5 and de Beaufort 1931; James 1975; Jones 1997; available at http://ncbi.nlm.nih.gov), and 1985; unpubl. data). Sequence Monkey 2.9.1 (Graf, 2000; available Fish tissues were either preserved in 95% at http://www.monkeysoftwerks.com). The ini- ethanol or stored frozen at Ϫ75ЊC prior to ex- tial 16S alignment was folded into stem and traction of DNA. Total genomic DNA was ex- loop regions using available secondary-struc- tracted from muscle or ®n clips via use of a ture models (Guttel and Fox, 1988; De Rijk et Qiagen Tissue Extraction Kit (QIAamp or al., 1994; Orti et al., 1996). Base-pair comple- QIAquick Tissue Kit) following the manufac- mentarity was veri®ed for all stem regions. turer's protocol. PCR was used to amplify a The protein-coding fragment (COI) was un- segment (ϳ600 bp) of DNA from the mito- ambiguously aligned using CLUSTAL X and chondrial large ribosomal subunit (16S) and a required no further adjustment. segment (ϳ750 bp) of cytochrome c oxidase subunit I (COI). Double-stranded ampli®ca- PHYLOGENY RECONSTRUCTION tions were performed in either 25 or 50␮l vol- umes containing 1ϫ PCR buffer, 2 mM All 1251 nucleotide characters were ana- lyzed simultaneously under the optimality MgCl2, 0.2 mM of each dNTP, 0.2±0.5 ␮M of each primer, 10±1000 ng of genomic DNA criterion of parsimony. Gaps were treated as (1±2 ␮l), and 1 unit of Taq polymerase. To a ®fth character state. Parsimony analyses amplify and sequence the 16S fragment, the were conducted using PAUP* 4.0b3 (Swof- primers 16S ar-L 5Ј-CGCCTGTTTAT- ford, 1998). No weighting schemes of any CAAAAACAT-3Ј and 16S br-H 5Ј-CCGGT- kind were applied. Heuristic searches were CTGAACTCAGATCACGT-3Ј (Kocher et performed with 1000 replications and ran- al., 1989; Palumbi, 1996) were used. To am- dom stepwise addition of taxa. Consistency plify and sequence the COI fragment, the Fol- indices (CI), retention indices (RI), and re- mer et al. (1994) primers LCO1490 5Ј-GGT- scaled consistency indices (RC) (Kluge and CAACAAATCATAAAGATATTGG-3Ј and Farris, 1969; Farris, 1989) were computed in HCO2198 5Ј-TAAACTTCAGGGTGACCA- PAUP*. To estimate the robustness of the AAAAATCA-3Ј were used. Ampli®cations phylogenetic hypothesis, Bremer support for 16S were carried out in 30 cycles accord- (Bremer, 1988, 1995) was calculated for all ing to the following temperature pro®le: de- recovered clades using TreeRot v.2 (Soren- naturation for 1 min at 94ЊC, annealing for 1 son, 1999; available at http://mightyduck.bu. min at 55ЊC, and extension for 2 min at 72ЊC, edu/TreeRot), and Jackknife resampling anal- with an additional terminal extension at 72ЊC yses (10,000 replications, heuristic searches, for 10 min. For COI, 35 cycles were run ac- 10 random stepwise additions per replication, cording to the following temperature pro®le: emulate Jac option selected) were performed denaturation for 30 sec at 94ЊC, annealing for using PAUP*. Patterns of character evolution 1 min at 45ЊC, and extension for 2 min at were examined using both PAUP*, PAUP 72ЊC, with an additional terminal extension at v.3.1.1 (D.L. Swofford, unpubl.), and 72ЊC for 10 min. The double-stranded ampli- MacClade (Maddison and Maddison, 1997). ®cation products were isolated on 1% agarose Ingroup relationships were unaffected re- gels, excised under UV light, and extracted gardless of whether carangids or gerreids using a Qiagen Gel Extraction Kit. Both were used to root the topology. Sequences strands of the puri®ed PCR fragments were are deposited at GenBank under the acces- used as templates and directly cycle-se- sion numbers listed in table 1. quenced using the original ampli®cation primers and an ABI Prism Dye Terminator Reac- RESULTS tion Kit. The sequencing reactions were elec- MOLECULAR ANALYSIS trophoresced on ABI 377 or ABI 3700 auto- mated DNA sequencers. A single optimal tree was recovered by DNA sequences were aligned and com- analysis of the combined, equally weighted piled using Sequence Navigator 1.0.1 (Ap- nucleotides from the mitochondrial 16S and plied Biosystems), Sequencher v.4.1 (Gene COI genes (1251 characters; 432 parsimony- Codes), CLUSTAL X (Thompson et al., 1994, informative sites; 1976 steps including only 6 AMERICAN MUSEUM NOVITATES NO. 3459 parsimony-informative sites; CI ϭ 0.402; RI hump (®g. 5A). Lateral snout outline mildly ϭ 0.555; RC ϭ 0.223), representing a diverse concave. Strong preorbital protuberance due assemblage of leiognathid species (®g. 2). to hypertrophy and protrusion of frontal and Monophyly of Leiognathidae (clade A) is lateral ethmoid ossi®cations (®g. 6A). Pre- very strongly supported by nucleotide char- dorsal head pro®le mostly straight to mildly acters (Bremer support [BS] ϭ 47; Jackknife curved; back not strongly arched. Nuchal [JK] ϭ 100%). Within Leiognathidae, two spine not protruding, and distal tip not ex- major clades were recovered and are also ro- posed (®gs. 3A, 4, 5A). Nuchal spine with bustly supported: clade B (BS ϭ 22; JK ϭ distinct median keel. Two short and stout 100%), comprising L. equulus and a mor- postnasal spines present on lateral ethmoid, phologically similar species described here- located posterior to nasal foramina and just in; and clade C (BS ϭ 8; JK ϭ 94), contain- rostrodorsal of orbit. Postnasal spines fol- ing all other members of Leiognathus togeth- lowed posteriorly by well-developed supra- er with all members of Gazza and Secutor. orbital ridges; ridges converge posteriorly. Both Gazza and Secutor are monophyletic, Dorsal and ventral pro®les about evenly as is an assemblage comprising Gazza ϩ Se- curved. Dorsal-®n origin about midway be- cutor. These relationships render the genus tween pelvic-®n and anal-®n origins. Anal- Leiognathus paraphyletic. Within clade C, a ®n origin at about level of vertical through number of less inclusive clades are recovered seventh dorsal-®n spine. Eye large. Caudal and most receive strong support. peduncle slender and shallow. Mouth small and terminal in position, directed slightly SYSTEMATIC ACCOUNT downward when protruded. Caudal margin of maxilla exposed, reaching to level of ver- Leiognathus robustus, new species tical through anterior margin of orbit. Ante- Figures 3±6 rior nasal pore round, posterior foramen cres- HOLOTYPE: UMMZ 242144, 183.4 mm SL, cent-shaped, partially encircling anterior adult male; Singapore: ®sh market; H.H. Ng, pore. Lower preopercular margin weakly ser- 16 July 2001. rate. Vertebral count: 9 precaudal ϩ 14 cau- PARATYPES: AMNH 233607, 1 ex., 167.9 dal ϭ 23. Neural and hemal spines of ver- mm SL, male; Singapore: ®sh market; H.H. tebral centrum PU4 expanded and bladelike Ng, July 2002; UMMZ 240362, 1 ex., 165.5 (®g. 6A). Fifteen or 16 stout and triangular mm SL, female; Singapore: ®sh market; H.H. outer ceratobranchial gill rakers arrayed Ng, July 2002. along lower limb (ϭ ceratobranchial one) of DIAGNOSIS: Leiognathus robustus is distin- ®rst gill arch. guished from the only other species of leiog- Fins: Dorsal ®n with VIII spines and 16 nathid known to possess a non-sexually di- branched rays. First dorsal-®n spine greatly morphic LOS, L. equulus, by the absence of reduced in length, yet relatively robust. Sec- an occipital hump (vs. pronounced hump), ond through fourth dorsal-®n spines elongate the presence of a mildly sloping predorsal and robust, second spine longest. Third and pro®le (vs. strongly curved, creating the im- fourth dorsal-®n spines serrate along anterior age of an arched back), frontal and lateral margin, ``lock'' into groove on preceding ethmoid ossi®cations that project anterodor- spine when erect. Dorsal-®n spines ®ve sally and extend well anterior of the orbit to through eight feeble, shorter than second form a distinct preorbital protuberance (vs. through fourth spines. Anal ®n with III slight bulge above orbit), and a nuchal spine spines and 14 branched rays. First anal-®n that is not exposed in lateral view (vs. ex- spine very short. Second and third anal-®n posed and projecting, particularly distally). spines robust and elongate, second spine lon- DESCRIPTION: Selected proportional mea- gest. Third anal-®n spine serrate on anterior surements and meristic data are presented in margin, ``locks'' into groove on posterior table 2. A deep-bodied and robust Leiogna- margin of second spine when erect. Spinous thus, which grows to a large size (Ͼ180 mm dorsal and anal ®ns with asquamate basal SL) (®gs. 3, 4). Body laterally compressed. sheath, creating furrow into which ®ns may No pronounced supraoccipital (ϭ predorsal) retract. Pelvic ®ns short, not reaching ®rst 2004 SPARKS AND DUNLAP: NON-SEXUALLY DIMORPHIC PONYFISHES 7

Fig. 2. Single optimal tree of leiognathid relationships recovered by combined analysis of mitochondrial (16S and COI) nucleotide characters. L. ϭ Leiognathus; G. ϭ Gazza; S. ϭ Secutor. Numbers above branches represent Bremer support and numbers below branches represent Jackknife resampling percentages (Ͼ50%). Letters at nodes correspond to clades discussed in text: clade A ϭ Leiognathidae; clade B ϭ leiognathids with non-sexually dimorphic LOS; clade C ϭ leiognathids bearing sexually dimorphic LOS. LOS features characteristic of members of recovered clades (Sparks and Dunlap, in review) are indicated on the topology. anal spine when adducted. Eight upper and Breast naked, asquamate region extending to seven lower branched caudal-®n rays. Nine- pectoral-®n base. Lateral line arched and teen total pectoral-®n rays. complete. Pored scales in lateral line number Dentition: Multiple rows of small, closely 60±65. Pores well developed. Pelvic axillary set, elongate and moderately recurved, villi- scale well developed and elongate. All ®ns form teeth present in both upper and lower asquamate. jaws. Four to ®ve closely set rows anteriorly PIGMENTATION IN PRESERVATION: Body and one to two rows posteriorly in upper jaw. ground coloration gray to grayish-blue dorsal Three to four rows anteriorly and one to two of midline, and pale yellow, white, or golden rows posteriorly in lower jaw. Lips ¯eshy ventral of midline. Iridescent golden patches and rugose. present to varying degree along lateral mid- Squamation: Body scales small and cy- line. Cheek and opercular region iridescent cloid. Head and opercular region naked. silvery to golden. Head above orbit and nape 8 AMERICAN MUSEUM NOVITATES NO. 3459 lotype. L. equulus , new species, and TABLE 2 Leiognathus robustus Morphometric and Meristic Data of Measurements (mm) are percentage standard length (SL) or percentage head length (HL), unless noted otherwise. H indicates count corresponding to ho 2004 SPARKS AND DUNLAP: NON-SEXUALLY DIMORPHIC PONYFISHES 9 grayish to grayish-brown. Snout dusky to of the type series. The overall similarity of blackish; appears spotty due to concentrated L. robustus to L. equulus, a common and melanophores. Nasal region and lips pale widespread species, or to other large leiog- yellow. Gular region with iridescent silvery nathid species such as L. dussumieri or L. or golden patches. Chest and belly white or fasciatus, suggest that L. robustus may be pale gray. Caudal peduncle and base of cau- easily misidenti®ed, and therefore may tra- dal ®n iridescent silvery or golden. Dorsal, ditionally have been overlooked in collec- anal, pectoral, and pelvic ®ns whitish to yel- tions. low. Dorsal ®n with black pigment distally. ETYMOLOGY: Named in reference to the ro- Pectoral-®n axil blackish due to concentra- bust nature and large size of the species com- tion of melanophores, surrounded by large pared to all congeners except L. equulus, its iridescent silver patch. Pectoral-®n base sil- sister taxon, and L. fasciatus. The speci®c very. Caudal ®n yellowish to light brown, epithet, robustus, is used as an adjective. dorsal and ventral rays with black pigment, especially proximal to base. Caudal ®n with DISCUSSION prominent black terminal band. Pelvic axillary scale and body along anal-®n base sil- COMPARISONS: This study describes Leiog- very or golden. Pores of lateral line scales nathus robustus, a new species and the sec- edged dorsally and ventrally with melano- ond member of the non-sexually dimorphic phores. clade of leiognathid ®shes recovered by anal- LIGHT-ORGAN SYSTEM (LOS) (®g. 3): Sex- ysis of nucleotide characters (®g. 2, clade B). ual dimorphism of the light organ and asso- Like L. equulus, the other member of this ciated structures is not detected. The light or- clade, the light organ and associated tissues gan of males is not enlarged compared to the of the LOS are not sexually dimorphic. The similarly sized conspeci®c female and does clade formed by these two species is quite not exhibit any apparent shape dimorphism. distinct from all other leiognathids based on The light organ is a comparatively simple, both morphology of the LOS (Sparks and dorsoventrally compressed, doughnut-shaped Dunlap, in review) and the analysis of nu- structure surrounding the esophagus (®g. cleotide characters. 3B). Neither the dorsal nor ventral lobes of Leiognathus robustus is easily misidenti- males are hypertrophied compared to the ®ed as L. equulus (®g. 7) and is also similar conspeci®c female examined. Likewise, as- in overall morphology to L. fasciatus and L. sociated structures of the LOS (e.g., clearing longispinis. These species exhibit no obvious of the gasbladder lining, modi®cations of the external sexual dimorphism, grow to large integument) do not exhibit any sexually di- size for leiognathids (Ͼ150 mm SL) (Wood- morphic attributes. As in all other leiognath- land et al., 2001; Froese and Pauly, 2003; ids, the posteroventral margin of the gasblad- personal obs.), and exhibit similar overall der chamber and the small, thin anteroventral body shape, coloration, and pigmentation. patch separating the light organ from the gas- Leiognathus fasciatus males, however, bear bladder are transparent. This `window' is moderately enlarged light organs compared sparsely `peppered' with iridescent silvery to similarly sized conspeci®c females, and bluish chromatophores. No lateral clear- though like L. robustus they lack any exter- ing of the silvery gasbladder lining is evident nal sexually dimorphic features of the LOS (®g. 3B). Externally sexually dimorphic fea- (McFall-Ngai and Dunlap, 1984; Sparks and tures of the LOS (i.e., male speci®c trans- Dunlap, in review). It is not known at this parent patches or stripes in the opercular re- time whether the LOS of L. longispinis is gion or on the ¯anks) are absent (®gs. 3A, sexually dimorphic; suitable material cur- 4). rently is lacking. DISTRIBUTION: Known at this time only Leiognathus robustus is distinguished from market specimens purchased in Singa- from L. equulus (ForsskaÊl, 1775) by the fea- pore. Given that the Singapore ¯eet ®shes tures listed above under the differential di- throughout much of the Indo-Paci®c basin, agnosis (viz. the absence of an occipital we are unable to report the collection locality hump [vs. prominent hump], the presence of 10 AMERICAN MUSEUM NOVITATES NO. 3459

Fig. 3. Leiognathus robustus, holotype, UMMZ 242144, 183.4 mm SL, adult male; Singapore. A. External anatomy, illustrating general pigmentation pattern, and absence of transparent ¯ank or opercular 2004 SPARKS AND DUNLAP: NON-SEXUALLY DIMORPHIC PONYFISHES 11

Fig. 4. Leiognathus robustus, holotype, UMMZ 242144, adult male, 183.4 mm SL, Singapore. a gently sloping predorsal pro®le [vs. strong- in L. dussumieri; Woodland et al., 2001), the ly curved, arched back], a distinct preorbital absence of a yellow patch between the pec- protuberance [vs. small bump above orbit], a toral and anal ®ns (although this patch could nuchal spine that is not visible in lateral view be faded in preservation and not discernable [vs. exposed and projecting distally]; ®gs 3± in our material), the absence of distinctive 7), and by the analysis of mitochondrial nu- and easily visualized, thin, dark vertical bars cleotide characters (®g. 2). In lateral view, on the ¯anks that extend to just below mid- the nuchal spine is clearly exposed in both line, by short pelvic ®ns that do not extend the lectotype and paralectotype of L. equulus to the ®rst anal spine (®g. 3A), and a larger (ZMUC P48219 and ZMUC P48220, respec- maximum adult size (Ͼ150 mm SL and tively) (®g. 8A). Width of the caudal pedun- Ͼ200 mm TL vs. 140 mm max. TL). cle (4.7±5.1% in L. robustus vs. 3.3±4.7% Leiognathus robustus is distinguished SL in L. equulus) and body depth at origin from L. fasciatus (LacepeÁde, 1803) by a of the anal ®n in adults (52.3±53.4% in L. much shorter second dorsal-®n spine (in L. robustus vs. 55.7±56.7% SL in L. equulus) fasciatus this spine is distinctly elongate), by are also generally useful features for distin- the presence of a non-sexually dimorphic guishing between the new species and L. light organ and LOS (vs. light organ mod- equulus. erately enlarged in L. fasciatus males), and The new species is distinguished from L. by the absence of prominent dark vertical dussumieri (Valenciennes, 1835) by the ab- bars on the ¯anks and above the lateral mid- sence of scales on the breast (vs. conspicuous line.

← patches. B. Schematic of internal LOS morphology. Light organ of males not enlarged and clearing of silvery gasbladder lining restricted to posterior of chamber, a condition common to all leiognathids. No lateral clearing of integument present in region of light organ. Abbreviations: es, esophagus; g, gut; gb, gasbladder; lo, light organ. Shaded region (designated by arrow) indicates clearing of silvery gasbladder lining. Drawings by Ian Hart. 12 AMERICAN MUSEUM NOVITATES NO. 3459

genetic analysis of leiognathid intrafamilial relationships, Gazza, Leiognathus, and Se- cutor were each generally assumed to be monophyletic. Our analysis of nucleotide characters revealed however that while Gaz- za and Secutor are indeed monophyletic, the genus Leiognathus comprises a paraphyletic assemblage (see also Sparks and Dunlap, in review) (®g. 2). Consistent with this ®nding, apomorphic features supporting monophyly of Gazza and Secutor have been identi®ed (e.g., Mochizuki and Hayashi, 1989; Kimura et al., 2000; Woodland et al., 2001; Sparks and Dunlap, in review), whereas none has been advanced to unite members of Leiog- nathus. Based on features of the LOS, members of Leiognathus comprise three morpho- logically distinct groups (®g. 2): a clade whose members possess non-sexually dimorphic light organs and that exhibit no internal or external sexually dimorphic attributes of the LOS (clade B; ®g. 1E, F), and two clades nested within clade C whose members possess sexually dimorphic light organs, most of which also possess associated internal and external sexually dimorphic features of the LOS (®g. 1A±D). One of these latter sexually dimorphic clades is the sister taxon to a clade comprising all members of Gazza and Se- cutor (®g. 2). Thus, the generally accepted but erroneous classi®cation scheme of leiognathids based on overall external similarity Fig. 5. Left lateral view of head of: (A) is now corrected in favor of a scheme based Leiognathus robustus, holotype, UMMZ 242144, on derived features of the LOS (Sparks and adult male, 183.4 mm SL; (B) Leiognathus equul- Dunlap, in review). us, UMMZ 238805, adult male, 173.4 mm SL. Given that Leiognathus must now be rec- Arrow indicates nuchal spine. ognized as a paraphyletic assemblage, prov- enance of the generic name is problematic. ForsskaÊl (1775) described the ®rst ®sh we The new species is distinguished from L. currently recognize as a leiognathid, Scom- longispinis (Valenciennes, 1835) by mark- ber equula, from two dry skins collected in edly shorter second dorsal- and anal-®n the Red Sea off of Yemen (®g. 8A). Klau- spines (vs. spines exceedingly elongate and sewitz and Nielsen (1965: 23) later desig- occasionally reaching to origin of the caudal nated a lectotype and paralectotype from ®n, Woodland et al., 2001). In addition, L. these specimens. We have examined photo- robustus lacks the faint and unevenly spaced, graphs and radiographs of both type speci- dorsal-¯ank blotches characteristic of L. lon- mens (ZMUC P48219, lectotype, 131 mm gispinis. As mentioned, it is not currently SL; ZMUC P48220, paralectotype, 120 mm known whether the LOS of L. longispinis ex- SL). The diagnostic arched back and promi- hibits any sexually dimorphic attributes, al- nent nuchal spine of specimens subsequently though we are working to obtain suitable attributed to L. equulus are clearly visible in study material. both the radiographs and photographs of the TAXONOMY: Prior to our molecular phylo- type specimens (®g. 8A). Although the lec- 2004 SPARKS AND DUNLAP: NON-SEXUALLY DIMORPHIC PONYFISHES 13

Fig. 6. Comparative radiographs of similarly sized (A) Leiognathus robustus, holotype, UMMZ 242144, adult male, 183.4 mm SL, and (B) Leiognathus equulus, UMMZ 238805, adult male, 173.4 mm SL. totype and paralectotype of Scomber equula scription of Scomber equula, Bloch (1795) could not be examined directly due to their described Scomber edentulus, apparently delicate nature, all relevant anatomical fea- from a single specimen, ZMB 8756 (dry left tures, aside from those of the LOS, could skin), for which he provided no collection easily be visualized via the examination of locality (®g. 8B). Thereafter, LacepeÁde detailed photographs and radiographs. (1802) described the genus Leiognathus from Twenty years subsequent to ForsskaÊl's de- the same specimen (ZMB 8756), which he 14 AMERICAN MUSEUM NOVITATES NO. 3459

Fig. 7. Leiognathus equulus, UMMZ 238805, adult male, 173.4 mm SL, Singapore. listed as having been collected in Tranquebar, Clearly, Scomber edentulus, Leiognathus India, and designated L. argenteus as the argenteus, and Equula ensifera are conspe- type species of the genus. Subsequent to this, ci®c, having all been described from the Cuvier (1829: 212) described Equula ensi- same specimen (ZMB 8756), with the name fera once again from the same specimen Scomber edentulus having priority. However, (ZMB 8756). As Eschmeyer (1998) pointed in the absence of detailed comparative anal- out, Equula ensifera is an available name yses we are hesitant to accept the synonymy from the footnote in Cuvier (1829: 212), of Scomber edentulus with Scomber equula ``Eq. ensifera, Nob., ou Scomber edentulus, as James (1975: 145), Dor (1984: 135), and Bl., 428, ou Leyognathe argenteÂ, Lacep.'' Fricke (1999: 260) have proposed. It is ap- This taxon was described again by Valenci- parent that James (1975), Dor (1984), and ennes in Cuvier and Valenciennes (1835: 66). Fricke (1999) did not examine and compare Cuvier (1815: 463) named Equula (``je nom- type material of the relevant taxa to reach merai equula''), with Scomber equula this conclusion. For example, Fricke (1999: (ForsskaÊl, 1775) (ϭ Centrogaster equula of 260) stated under ``Remarks'' that the syn- Gmelin, 1788) becoming the type species of onymies he listed for Leiognathus equulus the genus by absolute tautonymy (Eschmey- are a ``Taxonomic decision of James (1975: er, 1998). The subsequent synonymy of 145±147).'' Likewise, in the study of James Leiognathus argenteus LacepeÁde, 1802 (ϭ that Fricke refers to, no type specimens of Scomber edentulus Bloch) with Scomber the relevant taxa were examined, and in fact equula (ϭ Equula equula) required Equula only a single lot of (presumably) L. equulus therefore to become a junior synonym of from Indian waters, Palk Bay and the Gulf Leiognathus LacepeÁde, 1802 (James, 1975; of Mannar, was listed under ``Material'' by Dor, 1984; Fricke, 1999). Eschmeyer (1998) James (1975: 146). James (1975: 147) men- was correct in his assertion that L. argenteus tioned that the chest region in the specimens was an unneeded new name for Scomber ed- he examined is covered by diaphanous entulus Bloch, 1795. Likewise, Equula en- scales; however, we have examined material sifera was also an unneeded new name for spanning the putative geographic range of L. Scomber edentulus Bloch, 1795. equulus, including the type series, and con- 2004 SPARKS AND DUNLAP: NON-SEXUALLY DIMORPHIC PONYFISHES 15

Fig. 8. A. Scomber equula ForsskaÊl, lectotype, ZMUC P48219, dry skin, 131 mm SL, Yemen: Red Sea: Luhaiya. B. Scomber edentulus Bloch, holotype, ZMB 8756, dry left skin, India: Tranquebar. 16 AMERICAN MUSEUM NOVITATES NO. 3459 cur with Woodland et al. (2001) that this re- mulate a formal conclusion regarding the gion is indeed naked in L. equulus. Squa- identity of the two synonymized species. mation extends anteriorly in this region at Given the poor condition and delicate nature most to about the level of a vertical through of type material for these taxa, and that fea- pectoral-®n insertion. Without the direct tures of LOS morphology cannot be studied, comparison of type material for these mor- we may never be able to reach a ®rm con- phologically very similar taxa, James (1975) clusion regarding the identity and status of certainly had no justi®able means for pro- L. argenteus, the type species of Leiogna- posing the synonymies he lists for L. equul- thus. Without direct examination of the LOS us. Dor (1984: viii) likewise stated that ``My we cannot determine the intrafamilial place- work is mostly based on the literature'' and ment of Leiognathus argenteus (ϭ Scomber nowhere in the text does he present a list of edentulus) with certainty. There is little comparative material. Thus, in our opinion doubt that Scomber equula and Leiognathus the synonymies proposed in these three argenteus (ϭ Scomber edentulus) are closely works cannot be justi®ed at the present time. related; whether they are conspeci®c remains The type specimens of both Scomber to be determined. In light of these limita- equula and Scomber edentulus are dry partial tions, and until a more comprehensive phy- skins, and detailed comparative analyses are logenetic revision of the family is completed, problematic (®g. 8). Certainly the illustration we consider it prudent (and least disruptive) of Scomber edentulus (Bloch, 1795: pl. 428) to treat Scomber equula as a member of does not match well the overall gross exter- Leiognathus. This taxon is the most common nal morphology of L. equulus. The back (ϭ and widespread member of the family, and dorsal pro®le) does not appear strongly we think that any change in generic assign- arched as in L. equulus and there is no prom- ment at this time, without certainty regarding inent occipital hump. Examination of a pho- the placement and status of L. argenteus (ϭ tograph of the holotype of Scomber edentu- Scomber edentulus), would be counterpro- lous, however, appears to reveal both an ductive and lead to more confusion. arched back and prominent nuchal spine, de- LIGHT ORGAN SYSTEM: To examine evolu- spite the specimen's poor state of preservation of the leiognathid LOS within a phylo- tion (®g. 8B). Moreover, L. equulus lacks the genetic context we conducted a parsimony distinctive broad vertical bars present on the analysis of extant forms based on DNA se- ¯anks of Scomber edentulus, and the number quence data from two mitochondrial genes of dorsal ®n spines in L. equulus is seven to (COI and 16S). Two distinct clades were re- eight, never ®ve as illustrated by Bloch covered in this analysis, which revealed a (1795: pl. 428). Interestingly, as the species major phylogenetic divergence within Leiog- name implies, Bloch (1795) reported that nathidae. Members of one clade, which con- ``the small mouth [is] toothless.'' Contrary to tains most leiognathid species, exhibit sexual this claim, small teeth are indeed visible in dimorphism of the light organ (®g. 2, clade the desiccated lip tissue of the type specimen C). Most members of this clade also exhibit of S. edentulus (P. Bartsch [ZMB], personal sexual dimorphism of the associated tissues comm.] and must have been overlooked by of the LOS. Members of the other clade, re- Bloch. These discrepancies could simply be stricted to Leiognathus equulus and L. ro- due to errors or to exaggerated features in bustus, n. sp., bear light organs that are not Bloch's illustration and description, or they sexually dimorphic, and they exhibit no in- could result from damage to the holotype pri- ternal or external sexual dimorphism of as- or to description; however, we think that they sociated LOS tissues (®g. 2, clade B). Our are signi®cant enough that we are hesitant to phylogenetic results indicate that the nondi- accept the proposed synonymy of Scomber morphic state is plesiomorphic. Given that edentulus with Scomber equula. Even if one presumably all leiognathids are capable of could obtain permission to directly examine emitting light over their ventral surface the types of Scomber equula and Scomber (McFall-Ngai and Dunlap, 1983, 1984; edentulus, all dry partial skins in poor con- McFall-Ngai and Morin, 1991), whereas only dition, it likely would not be possible to for- some sexually dimorphic species possess the 2004 SPARKS AND DUNLAP: NON-SEXUALLY DIMORPHIC PONYFISHES 17 modi®cations necessary for lateral lumines- rally for reproduction (McFall-Ngai and cence (®g. 2) (McFall-Ngai and Dunlap, Dunlap, 1984; Herring and Morin, 1978) in 1984; Sparks and Dunlap, in review), we hy- a manner analogous to the species-speci®c pothesize that the LOS originally evolved for male courtship ¯ashing utilized by ®re¯ies ventral counterillumination, possibly as a and ostracodes (Lloyd, 1966; Morin, 1986; means of avoiding bottom-dwelling preda- Morin and Cohen, 1991; Branham and tors (Sparks and Dunlap, in review). Green®eld, 1996). Sexual selection for spe- The LOS of leiognathid ®shes exhibits cies-speci®c luminescence signaling presum- species-speci®c differences in the size and ably plays a key role in generating and main- shape of the light organs (®g. 1). In addition, taining species diversity within Leiognathi- most leiognathid species exhibit a sexually dae (Sparks and Dunlap, in review). dimorphic LOS, with the light organs of Features of the LOS are reliable markers males being moderately to highly enlarged of phylogeny and their use is critical in com- compared to that of similarly sized conspe- parative studies of pony®shes (®g. 2), the ci®c females (Haneda and Tsuji, 1976; Dun- members of which otherwise exhibit a high lap and McFall-Ngai, 1984; McFall-Ngai and degree of morphological conservatism (Dun- Dunlap, 1984; Jayabalan and Ramamoorthi, lap and McFall-Ngai, 1984; Sparks and Dun- 1985; Jayabalan, 1989; Kimura et al., 2003; lap, in review). Many taxonomic questions Sparks and Dunlap, in review) (®g. 1B, D). concerning this group of ®shes can only be For example, the light organ of a male Leiog- addressed through examination and compar- nathus elongatus typically is 20 times larger ison of LOS features, and even when other in volume than conspeci®c females of similar morphological characters clearly distinguish standard length, and may be up to 100 times species, features of the LOS can serve to cor- larger (Dunlap and McFall-Ngai, 1984; roborate and support the membership of in- McFall-Ngai and Dunlap, 1984) (®g. 1B). In dividual species in species assemblages (Ki- most cases, leiognathids bearing sexually di- mura et al., 2003). The very substantial dimorphic light organs also exhibit male-spe- versi®cation of leiognathids bearing sexually ci®c transparency of the internal re¯ective dimorphic LOS, evolving apparently under lateral lining of the gasbladder (certain selection pressure for species-speci®c male Leiognathus species) (®gs. 1B, 2), male-spe- luminescence signaling, from a relatively ci®c transparent patches (i.e., windows) on simple, non-sexually dimorphic state that is the external lateral ¯ank or behind the pec- retained by very few extant species (®g. 2, toral-®n axil (certain Leiognathus species) clade B), accounts for the large number of (®gs. 1A, C, 2), or male-enhanced transpar- phylogenetically-informative characters of ent patches on the margin of the opercular the LOS (Sparks and Dunlap, in review). cavity (Gazza and Secutor) (®g. 2). The pres- The sexually dimorphic nature of the ence of these modi®cations correlates with leiognathid LOS suggests that it functions in hypertrophy of dorsolateral or ventrolateral mate choice, possibly as a reproductive iso- lobes of the light organ in males, enabling lating mechanism similar to that documented males to emit light laterally (Haneda and for ®re¯ies (Lloyd, 1966) and ostracodes Tsuji, 1976; McFall-Ngai and Dunlap, 1984; (Morin, 1986; Morin and Cohen, 1991). Al- Kimura et al., 2003). Like emission of light though direct observation of unique ¯ashing from the light organ, which is under control patterns for most species of leiognathid are of the ®sh via retraction and relaxation of the currently lacking (McFall-Ngai and Dunlap, light-organ shutters, light emission from the 1983; Sasaki et al., 2003), we think that the transparent external windows also is under morphological variation and modi®cations the ®sh's control (McFall-Ngai and Dunlap, reported for the LOS in male pony®shes 1983, 1984). A major function of the leiog- (Sparks and Dunlap, in review), in light of nathid LOS therefore may be mate-speci®c the recovered phylogeny, present compelling recognition (Andersson, 1994; Paterson, evidence for a system of sexual selection 1985), with luminescence signaling by males based on species-speci®c male ¯ashing pat- operating to attract females, induce spawn- tern. We hypothesize that variation of the ing, or segregate species spatially or tempo- LOS has permitted a number of morpholog- 18 AMERICAN MUSEUM NOVITATES NO. 3459 ically similar forms to coexist and maintain ner). Zeitschrift fuÈr Wissenschaftliche Zoologie species ®delity, frequently in habitats with 173: 90±113. extremely poor visibility. This system, which Andersson, M. 1994. Sexual selection. Princeton, apparently represents a unique mechanism of NJ: Princeton University Press. sexual selection in ®shes, demonstrates that Bassot, J.M. 1975. Les organes lumineux aÁ bac- teÂries symbiotiques de quelques teÂleÂosteÂens bioluminescent symbiosis has been important Leiognathides. Archives de Zoologie Experi- not only in determining the patterns of spe- mentale et Generale 116: 359±373. cies diversi®cation in pony®shes, but in Bloch, M.E. 1795. Naturgeschichte der AuslaÈn- maintaining that diversity as well (Sparks dischen Fische, vol. 9. Berlin: Im Verlage der and Dunlap, in review). The recovery of a Morinofchen Kunfthandlung, i±ii ϩ 1±192. clade of non-sexually dimorphic leiognath- Boisvert, H., R. Chatelain, and J.M. Bassot. 1967. ids, containing at this time just two member EÂ tude d'un Photobacterium isoleÂ de l'organe species, L. equulus and L. robustus, serves lumineux des poissons Leiognathidae. Annales as an evolutionarily and ecologically intrigu- de l'Institut Pasteur (Paris) 112: 520±524. ing counterpoint to the much more numerous Branham, M., and M.D. Green®eld. 1996. Flash- ing males win mate success. Nature 381: 745± and phylogenetically diverse, sexually di- 746. morphic pony®shes. Bremer, K. 1988. The limits of amino-acid sequence data in angiosperm phylogenetic recon- ACKNOWLEDGMENTS struction. Evolution 42: 795±803. Bremer, K. 1995. Branch support and tree stabil- We are grateful to H.H. Ng (UMMZ) for ity. Cladistics 10: 295±304. providing us with specimens of the new spe- Cuvier, G. 1815. Suite des observations et re- cies, and to C. Lavilla-Pitogo and J. Ledesma cherches critiques sur diffeÂrens poissons de la (SEAFDEC), S. Kimura (FRLM), and T. MeÂditerranneÂe, et aÁ leur occasion sur des pois- Yoshino (Univ. Ryukyus) for assistance in sons d'autres mers, plus ou moins lieÂs avec eux. acquiring ®sh specimens and in ®sh identi- Memoirs du Museum National d'Histoire Na- ®cations. We thank S. Jewett, L. Parenti, and turelle 1(4): 451±466. J. Williams (USNM), J. Leis, M. Mc- Cuvier, G. 1829. Le reÁgne animal, distribueÂ Grouther, and T. Trnski (AMS), Romain d'apreÁs son organisation, pour servir de base aÁ Causse and Patrice Pruvost (MNHN), and D. l'histoire naturelle des animaux et d'introduction aÁ l'anatomie compareÂe, 2nd ed., vol. 2. Catania and W. Eschmeyer (CAS) for the Paris: Chez Detarville, i±xv ϩ 1±406. loan of specimens in their care. J.S.S. further De Rijk, P., Y. Van de Peer, S. Chapelle, and R. thanks S. Jewett, L. Parenti, and J. Williams De Wachter. 1994. Database on the structure of for their hospitality during a visit to examine large ribosomal subunit RNA. Nucleic Acids collections at the USNM. J. Nielsen (ZMUC) Research 22: 3495±3501. and P. Bartsch (ZMB) provided detailed pho- Dor, M. 1984. CLOFRES. Checklist of the ®shes tographs and radiographs of critical type ma- of the Red Sea. Jerusalem: Israel Academy of terial in their care. D. Nelson was extremely Sciences and Humanities, i±xxii ϩ 1±437. helpful with the loan of material and the cur- Dunlap, P.V. 1984. Physiological and morpholog- ation of specimens deposited at UMMZ. Se- ical state of the symbiotic bacteria from light quencing was conducted in part by staff at organs of pony®sh. Biological Bulletin 167: 410±425. the University of Michigan Sequencing Core. Dunlap, P.V., and M.J. McFall-Ngai. 1984. Leiog- I. Hart produced the drawing of the new spe- nathus elongatus (Perciformes: Leiognathidae): cies. This work was initiated while J.S.S. was two distinct species based on morphological and a research associate at the University of light organ characters. Copeia 1984: 884±892. Michigan. Support was provided to J.S.S. by Dunlap, P.V., and M.J. McFall-Ngai. 1987. Initi- the American Museum of Natural History, ation and control of the bioluminescent sym- and to P.V.D. by the University of Michigan biosis between Photobacterium leiognathi and Center for Japanese Studies. leiognathid ®sh. In J.J. Lee and J.F. Fredrick (editors), Endocytobiology III. Annals of the REFERENCES New York Academy of Sciences 503: 269±283. Eschmeyer, W.N. 1998. Catalog of ®shes. Online Ahrens, G. 1965. Untersuchungen am Leuchtor- database version (updated March 13, 2003). gan von Leiognathus klunzingeri (Steindach- San Francisco: California Academy of Sci- 2004 SPARKS AND DUNLAP: NON-SEXUALLY DIMORPHIC PONYFISHES 19

ences, http://www.calacademy.org/research/ schrift fuÈr Wissenschaftliche Zoologie 131: ichthyology/catalog/®shcatsearch.html. 157±179. Farris, J.S. 1989. The retention index and the re- Hastings, J.W. 1971. Light to hide by: ventral lu- scaled consistency index. Cladistics 5: 417± minescence to camou¯age the silhouette. Sci- 419. ence 173: 1016±1017. Folmer, O., M. Black, W. Hoeh, R. Lutz, and R. Hastings, J.W., and G. Mitchell. 1971. Endosym- Vrijenhoek. 1994. DNA primers for ampli®ca- biotic bioluminescent bacteria from the light or- tion of mitochondrial cytochrome c oxidase gans of pony ®sh. Biological Bulletin (Woods subunit I from diverse metazoan invertebrates. Hole) 141: 261±268. Molecular Marine Biology and Biotechnology Herring, P.J., and J.G. Morin. 1978. Biolumines- 3: 294±299. cence in ®shes. In P.J. Herring (editor), Biolu- ForsskaÊl, P. 1775. Descriptiones animalium av- minescence in action: 273±329. London: Aca- ium, amphibiorum, piscium, insectorum, ver- demic Press. mium; quae in itinere orientali observavit Pe- James, P.S.B.R. 1975. A systematic review of the trus ForskaÊl Prof. Haun. Post mortem auctoris ®shes of the family Leiognathidae. Journal of edidit Carsten Niebuhr. Hauniae: ex of®cina the Marine Biological Association of India 17: MoÈlleri, 1±20 ϩ i±xxxiv ϩ 1±164. 138±172. Fricke, R. 1999. Fishes of the Mascarene Islands Jayabalan, N. 1989. Comparative morphology of (ReÂunion, Mauritius, Rodriguez). An annotated light organ systems in pony®shes (Leiognathi- checklist with descriptions of new species. dae). Indian Journal of Fisheries 36: 315±321. KoÈnigstein: Koeltz Scienti®c Books, i±viii ϩ Jayabalan, N., and K. Ramamoorthi. 1985. Sexual 1±759. dimorphism in the pony®sh, Leiognathus bin- Froese, R., and D. Pauly (editors). 2003. Fish- dus (Val). Current Science 54: 1191±1192. Base. Published online (updated version 1 Sept. Jones, G. 1985. Revision of the Australian species 2003), http://www.®shbase.org. of the ®sh family Leiognathidae. Australian Gmelin, J.F. 1788. Caroli a LinneÂ . . . Systema Na- Journal of Marine and Freshwater Research 36: turae per regna tria naturae, secundum classes, 559±613. ordines, genera, species; cum characteribus, dif- Kimura, S., T. Yamashita, and Y. Iwatsuki. 2000. ferentiis, synonymis, locis. Editio decimo tertia, A new species, Gazza rhombea, from the Indo- aucta, reformata. 3 vols. Lipsiae, 1788±93. Sys- West Paci®c, with a redescription of G. achla- tema Naturae LinneÂ v. 1 (pt 3): 1033±1516 [®sh- mys Jordan & Starks, 1917 (Perciformes: Leiog- es pp. 1126±1516]. [1806 English translation of nathidae). Ichthyological Research 47: 1±12. Latin original. LinneÂ, C. (1806), A general sys- Kimura, S., P.V. Dunlap, T. Peristiwady, and C.R. tem of nature, through the three grand kingdoms Lavilla-Pitogo. 2003. The Leiognathus aureus of animals, vegetables, and minerals, systemati- complex (Perciformes: Leiognathidae), with the cally divided into their special classes, orders, description of a new species. Ichthyological genera, species, and varieties, with their habita- Research 50: 221±232. tions, manners, economy, structure and peculiar- Klausewitz, W., and J.G. Nielsen. 1965. On Forss- ities: translated from Gmelin, Fabricius, Willd- kaÊl's collection of ®shes in the Zoological Mu- enow, et al. London: Lackington, Allen, and seum of Copenhagen. Spolia Zoologica Musei Co.] [®shes pp. 701±932] Hauniensis 22: 1±29. Graf, D.L. 2000. Sequence Monkey v. 2.9.1. Ann Ar- Kluge, A.G., and J.S. Farris. 1969. Quantitative bor: University of Michigan. Available at http:// phyletics and the evolution of anurans. System- www.members.tripod.com/sequence࿞monkey. atic Zoology 18: 1±32. GuÈnther, A. 1862. Catalogue of the Acanthopter- Kocher, T.D., W.K. Thomas, A. Meyer, S.V. Ed- ygii Pharyngognathi and Anacanthini in the wards, S. Paabo, F.X. Villablanca, and A.C. collection of the British Museum. Catalogue of Wilson. 1989. Dynamics of mitochondrial the ®shes in the British Museum. Vol. 4. Lon- DNA evolution in animals: ampli®cation and don: Taylor and Francis, i±xxi ϩ 1±534. sequencing with conserved primers. Proceed- Guttel, R.R., and G.E. Fox. 1988. A compilation ings of the National Academy of Sciences of of large subunit rRNA sequences presented in the USA 86: 6196±6200. a structural format. Nucleic Acids Research LacepeÁde, B.G.E. 1802. Histoire naturelle des 16S: r175±r269. poissons, vol. 4. Paris: Chez Plasson, Impri- Haneda, Y., and F.I. Tsuji. 1976. The luminescent meur-Libraire, i±xliv ϩ 1±728. system of pony®shes. Journal of Morphology LacepeÁde, B.G.E. 1803. Histoire naturelle des 150: 539±552. poissons, vol. 5. Paris: Chez Plasson, Impri- Harms, J.W. 1928. Bau and Entwicklung eines ei- meur-Libraire, i±lxviii ϩ 1±803 ϩ index. genartigen Leuchtorgans bei Equula spec. Zeit- Leviton, A.E., R.H. Gibbs Jr., E. Heal, and C.E. 20 AMERICAN MUSEUM NOVITATES NO. 3459

Dawson. 1985. Standards in herpetology and Reichelt, J.L., K. Nealson, and J.W. Hastings. ichthyology: Part I. Standard symbolic codes 1977. The speci®city of symbiosis: pony®sh for institutional resource collections in herpe- and luminous bacteria. Archives of Microbiol- tology and ichthyology. Copeia 1985: 802±832. ogy 112: 157±161. Lloyd, J.E. 1966. Studies on the ¯ash communi- Sasaki, A., K. Ikejima, S. Aoki, N. Azuma, N. cation system in Photinus ®re¯ies. Miscella- Kashimura, and M. Wada. 2003. Field evidence neous Publications, Museum of Zoology, Uni- for bioluminescent signaling in the pony ®sh, versity of Michigan 130: 1±95. Leiognathus elongatus. Environmental Biology Maddison, W.P., and D.R. Maddison. 1997. of Fishes 66: 307±311. MacClade: analysis of phylogeny and character Sorenson, M.D. 1999. TreeRot, v. 2. Boston: Bos- evolution, v. 3.07. Sunderland, MA: Sinauer. ton University. Available at http://mightyduck. McFall-Ngai, M.J. 1983. Adaptations for re¯ec- bu.edu/TreeRot. tion of bioluminescent light in the gas bladder Sparks, J.S., and P.V. Dunlap. In review. Light to of Leiognathus equulus (Perciformes: Leiog- mate by: evolution of a sexually-dimorphic lu- nathidae). Journal of Experimental Zoology minescent system in pony®shes (Teleostei: Per- 227: 23±33. ciformes: Leiognathidae). McFall-Ngai, M.J., and P.V. Dunlap. 1983. Three Swofford, D.L. 1998. PAUP* 4.0b3. Phylogenetic new modes of luminescence in the leiognathid analysis using parsimony, v. 4. Sunderland, ®sh Gazza minuta: discrete projected lumines- MA: Sinauer. cence, ventral body ¯ash, and buccal lumines- Taylor, W.R., and G.C. Van Dyke. 1985. Revised cence. Marine Biology 73: 227±237. procedures for staining and clearing small ®sh- McFall-Ngai, M.J., and P.V. Dunlap. 1984. Exter- es and other vertebrates for bone and cartilage nal and internal sexual dimorphism in leiog- study. Cybium 9: 107±119. nathid ®shes: morphological evidence for sex- Thompson, J.D., T.J. Gibson, F. Plewniak, F. Jean- speci®c signaling. Journal of Morphology 182: mougin, and D.G. Higgins. 1997. The CLUS- 71±83. TAL࿞X windows interface: ¯exible strategies McFall-Ngai, M.J., and J.G. Morin. 1991. Cam- for multiple sequence alignment aided by qual- ou¯age by disruptive illumination in leiognath- ity analysis tools. Nucleic Acids Research 25: ids, a family of shallow-water, bioluminescent 4876±4882. Available from http://ncbi.nlm. ®shes. Journal of Experimental Biology 156: nih.gov. 119±137. Thompson, J.D., D.G. Higgins, and T.J. Gibson. Mochizuki, K., and M. Hayashi. 1989. Revision 1994. CLUSTAL-W: improving the sensitivity of the leiognathid ®shes of the genus Secutor, of progressive multiple sequence alignment with two new species. Science Report of the through sequence weighting, position-speci®c Yokosuka City Museum 37: 83±95. gap penalties and weight matrix choice. Nu- Morin, J.G. 1986. ``Fire¯eas'' of the sea: lumi- cleic Acids Research 22: 4673±4680. nescent signaling in marine ostracode crusta- Valenciennes, A. 1835. Des Equula. In G. Cuvier ceans. Florida Entomologist 69: 105±121. and A. Valenciennes (editors), Histoire naturel- Morin, J.G., and A.C. Cohen. 1991. Biolumines- le des poissons. Tome dixieÁme: 60±103, pls. cent displays, courtship, and reproduction in os- 283±284. Paris: Chez F.G. Levrault, i±xxiv ϩ tracodes. In R. Bauer and J. Martin (editors), 1±482 ϩ 2 pp. Crustacean sexual biology: 1±16. New York: Weber, M., and L.F. de Beaufort. 1931. The ®shes Columbia University Press. of the Indo-Australian Archipelago. Vol. 6. Per- Orti, G., P. Petry, J.I.R. Porto, M. JeÂgu, and A. ciformes (continued). Leiden: E. J. Brill. Meyer. 1996. Patterns of nucleotide change in Woodland, D.J., S. Premcharoen, and A.S. Caban- mitochondrial ribosomal RNA genes and the ban. 2001. Leiognathidae: Slipmouths (pony- phylogeny of Piranhas. Journal of Molecular ®shes). In K.E. Carpenter and V.H. Niem (ed- Evolution 42: 169±182. itors), Species identi®cation guide for ®shery Palumbi, S.R. 1996. Nucleic acids II: the poly- purposes. The living marine resources of the merase chain reaction. In D. M. Hillis, C. Mo- Western Central Paci®c. Bony ®shes part 3 ritz, and B.K. Mable (editors), Molecular sys- (Menidae to Pomacentridae): 2792±2823. tematics. 2nd ed.: 205±247. Sunderland, MA: Rome: FAO. Sinauer. Woodland, D.J., A. S. Cabanban, V.M. Taylor, and Paterson, H.E.H. 1985. The recognition concept R.J. Taylor. 2002. A synchronized rhythmic of species. In E.S. Vrba (editor), Species and ¯ashing light display by schooling Leiognathus speciation. Transvaal Museum Monograph 4: splendens (Leiognathidae: Perciformes). Ma- 21±29. rine and Freshwater Research 53: 159±162. 2004 SPARKS AND DUNLAP: NON-SEXUALLY DIMORPHIC PONYFISHES 21

APPENDIX 1

MATERIAL EXAMINED UMMZ 191520; UMMZ 235029; UMMZ 238805 (in part); UMMZ 240133; UMMZ Nucleotide sequences for taxa included in the 240502; UMMZ 240503; UMMZ 240360; molecular phylogenetic analysis are deposited in UMMZ uncat. GenBank under accession numbers AY541648± Leiognathus fasciatus: AMNH 15520; CAS 1872; AY541672 for 16S, and AY541623±AY541647 UMMZ 240504; UMMZ 240361; UMMZ un- for COI (table 1). The notation ``(in part)'' fol- cat. lowing some catalog numbers indicates that the Leiognathus hataii: UMMZ uncat. alcoholic lot examined was found to contain more Leiognathus cf. hataii: AMNH 89922. than a single species. Leiognathus jonesi: UMMZ 240134; UMMZ 240505; UMMZ uncat. LEIOGNATHIDAE Leiognathus leuciscus: UMMZ 240125; UMMZ Gazza achlamys: UMMZ 240128; UMMZ uncat. 240132; UMMZ 240139. Leiognathus longispinis (ϭ L. smithursti): AMNH Gazza minuta: AMNH 220748; AMNH uncat.; 219296; AMS I.20907036; AMS I.22974001; UMMZ 191542; UMMZ 240126; UMMZ AMS 22981001; AMS 23044001. 240140; UMMZ 240141. Leiognathus moretoniensis: AMS I.21700001; Leiognathus aureus: UMMZ 240129; UMMZ un- AMS I.22983001. cat. Leiognathus nuchalis: AMNH 26819; CAS-SU Leiognathus bindus: CAS 51097; UMMZ 4757; UMMZ 240143. 240131; UMMZ 240142; UMMZ uncat. Leiognathus panayensis: UMMZ 240137; UMMZ Leiognathus blochii: MNHN A-6757, syntype, 1 uncat. ex.; MNHN A-6759, syntype, 1 ex. Leiognathus philippinus: UMMZ 240130. Leiognathus dussumieri: MNHN A-6721, syn- Leiognathus rivulatus: AMNH 34850; UMMZ type, 1 ex.; AMNH uncat. 240144; UMMZ uncat. Leiognathus edentulus: ZMB 8756, holotype (dry Leiognathus splendens: CAS 1485; CAS 38789; skin; photograph and radiographs examined). CAS 56438; CAS 56441; UMMZ 191202; Leiognathus elongatus: BMNH 1872.4.6, holo- UMMZ uncat. type; CAS 52602; LACM 42993-1; LACM Leiognathus stercorarius: USNM 55906, holo- 43584-1; SIO 83-55; USNM 55613; UMMZ type; USNM 126395, cotype; CAS 42171, 226771; UMMZ 240145; UMMZ uncat. paratype; CAS 17678; CAS-SU 20004, para- Leiognathus equulus: ZMUC P48219, lectotype type; UMMZ 240138; UMMZ uncat. (dry skin; photographs and radiographs exam- Secutor indicius: UMMZ 240127; UMMZ uncat. ined); ZMUC P48220, paralectotype (dry skin, Secutor insidiator: CAS 29894; UMMZ uncat. photograph and radiograph examined); AMNH Secutor megalolepis: UMMZ 240135. 59535; AMNH 88039; CAS 57306; CAS-SU Secutor ruconius: CAS-SU 29895; UMMZ 35627; CAS-SU 38781; MNHN A-6723; 225240; UMMZ uncat. Recent issues of the Novitates may be purchased from the Museum. Lists of back issues of the Novitates and Bulletin published during the last ®ve years are available at World Wide Web site http://library.amnh.org. Or address mail orders to: American Museum of Natural History Library, Central Park West at 79th St., New York, NY 10024. TEL: (212) 769-5545. FAX: (212) 769- 5009. E-MAIL: [email protected]

a This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper).