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A New Species of Ponyfish (Teleostei: Leiognathidae: Photoplagios) from
the Philippines
JOHN S. SPARKS AND PROSANTA CHAKRABARTY
A new species of ponyfish in the genus Photoplagios is described from material
collected in the Philippines. Photoplagios laterofenestra, new species, is distinguished
from congeners by the presence in males of an expansive translucent flank patch in the
shape of a cornucopia. Additionally, both sexes of the new species can be distinguished
from congeners by body shape, pigmentation pattern on the upper flank, and length of
the second dorsal-fin spine.
P
HOTOPLAGIOS comprises eight species: P.
rivulatus, P. leuciscus, P. elongatus, P. klunzingeri,
P. stercorarius, P. moretoniensis, P. antongil, and a new
species described herein. Members of Photoplagios
are markedly sexually dimorphic. Males are distin-
guished from all other members of Leiognathidae
externally by the presence of an expansive, trans-
lucent lateral flank patch or stripe. Internally, males
are distinguished by dorsolateral lobes of the light
organ that are hypertrophied and that extend
slightly to extensively into the gas bladder, and by
expansive lateral clearing of the silvery, guanine-
covered gas-bladder lining (Sparks et al., 2005).
Clearing of the reflective gas-bladder lining is
directly correlated in placement to the species-
specific translucent lateral flank patches or stripes.
Gas bladder clearing facilitates the lateral emission
of bacterially-generated luminescence via the flank
patches (Sparks et al., 2005). Males of all species of
Photoplagios are easily distinguished from each other
by size, shape, and placement of the translucent
lateral flank patch or stripe (Fig. 1). Species of
Photoplagios have dorsolateral lobes of the light
organ that extend to some extent into the gas
bladder and by lateral clearing of the gas-bladder
lining; however, both of these features are far less
pronounced in females than in males (Sparks et al.,
2005). Photoplagios adults generally have shallower
bodies than other leiognathid genera, but the
presence of a shallow body is not unique to the
genus.
In the present study, a new species belong-
ing to the genus Photoplagios is described from
material collected from the Samar Sea in the
Philippines. Placement of the new species
within Photoplagios is discussed with reference
to homologous features of the light-organ
system, which includes the circumesophageal
light organ and associated structures (e.g.,
clearing of the gas-bladder lining, transparent
flank, opercular, and gular patches) that facili-
tate the transmission of bacterially-generated
luminescence.
M
ATERIALS AND METHODS
Osteological features of the new species and
related taxa were examined using radiographs
and specimens cleared and stained (CS) for bone
and cartilage (following Taylor and Van Dyke,
1985). Light organs were examined in situ or
isolated to permit detailed morphological com-
parisons. Morphometric measurements were
recorded to the nearest 0.1 mm using dial
calipers. Standard length (SL) is used through-
out. Vertebral counts exclude the ural centrum
(5last half-centrum). The first caudal vertebra is
here defined as the first vertebra bearing
a definite hemal spine (Hubbs and Lagler,
1949). Vertebral and fin-spine/ray counts were
obtained from radiographs. The terminal dorsal-
fin and anal-fin rays, which are branched to the
base of the fin, are counted as a single element.
Pored scales in the lateral line are counted in
series from the dorsal margin of the gill opening
to the caudal flexure. Scale counts should be
interpreted as approximations, due to high
intraspecific variability, irregular arrangement,
the deciduous nature of ponyfish scales in
preservation, and because small scale size and
the degree to which scales are embedded make
accurate counts problematic. Institutional abbre-
viations follow Leviton et al. (1985).
A principal components analysis (PCA) was
conducted to identify shape-related differences
between the new species and congeners. Digital
images were taken from the left side of each
specimen. Only specimens that were preserved
unbent and of adult size were used in this
analysis. Landmarks (putatively homologous
points on anatomical structures) were chosen in
order to best represent the external shape of the
body (Fig. 2). The software tpsDIG2 (version
2.05, Rohlf, 2006, http://life.bio.sunysb.edu/
morph/) was used to digitize the landmarks on
the images. Generalized least squares (GLS)
Procrustes superimposition was performed to
Copeia, 2007(3), pp. 622–629
#
2007 by the American Society of Ichthyologists and Herpetologists
Fig. 1. Photographs of Photoplagios males, showing differences in shape of translucent flank patch: (A)
Photoplagios elongatus (UMMZ uncat. [PVD 82-06/19a LE], 76.4 mm SL). (B) P. rivulatus (UMMZ uncat.
[PVD 82-06/19a LR], 70.2 mm SL). (C) P. leuciscus (AMS I.22978004, 95.8 mm SL). (D) P. klunzingeri
(NMW 68280, syntype, 75.0 mm SL).
SPARKS AND CHAKRABARTY—NEW SPECIES OF PHOTOPLAGIOS 623
remove size from the data. In the optimal
superimposition, the distance minimized is the
Procrustes distance, calculated as the square root
of the summed squared distances between
homologous landmarks (Rohlf and Slice, 1990;
Goodall, 1991). This superimposition, and the
PCA, was performed using PCAgen (Sheets, 2001,
http://www2.canisius.edu/,sheets/morphsoft.
html).
Photoplagios laterofenestra, new species
Figures 3–4, Table 1
Holotype.—USNM 387899, 115.2 mm SL, adult
male, Philippines, Samar Sea, Carigara Bay, 0–
86 m depth, 11u559 420N, 124u289480 Eto
11u539480N, 124u299060E, 30 April 1980, C. Ferraris.
Paratypes.—AMNH 238682, 2, 115.3–121.0 mm
SL, data as for holotype; USNM 228508, 4, 115.9–
127.9 mm SL, data as for holotype.
Diagnosis.—Males of Photoplagios laterofenestra are
distinguished from all congeners by the presence
of an expansive cornucopia-shaped translucent
lateral flank patch. Both sexes of the new species
can be further distinguished from P. elongatus and
P. rivulatus, each of which possess a more or less
bullet-shaped flank patch, by a deeper body (34.4–
39.2 vs. 12.5–29.7% of SL in P. elongatus and P.
rivulatus) and pigmentation pattern on the upper
flank (vermiculate, with thin wavy lines forming
semi-circles and oval shapes vs. larger rounded
blotches in P. elongatus and P. rivulatus). Males and
females of the new species can be further
distinguished from P. leuciscus and P. klunzingeri,
both of which possess a triangular flank patch, by
the lack of a markedly elongate second dorsal-fin
spine and the pigmentation pattern on the upper
flank (vermiculate, with thin wavy lines forming
semi-circles and oval shapes vs. speckled in P.
leuciscus and P. klunzingeri). Adults of both sexes of
the new species also grow to a larger size than
congeners, except P. leuciscus.
Description.—Selected proportional measure-
ments and meristic data presented in Table 1.
A comparatively large, shallow bodied, and
laterally compressed species of ponyfish. Dorsal
profile slightly more convex than ventral. Deep-
Fig. 2. Landmarks used for Principal Components Analysis: (1) rostral tip of premaxilla, (2) posterior
end of nuchal spine, (3) anterior insertion of dorsal fin, (4) posterior insertion of dorsal fin, (5) dorsal
insertion of caudal fin, (6) midpoint of caudal border of hypural plate, (7) ventral insertion of caudal fin,
(8) posterior insertion of anal fin, (9) anterior insertion of anal fin, (10) dorsal base of pelvic fin, (11)
ventral end of lower jaw articulation, (12) posterior end of maxilla, (13) anterior margin through midline of
orbit, (14) posterior margin through midline of orbit, (15) dorsal end of opercle, (16) dorsal base of
pectoral fin. Base figure modified from Nelson (2006).
624 COPEIA, 2007, NO. 3
est part of body at vertical from dorsal-fin origin
to pelvic-fin origin. Lateral snout outline nearly
straight. Slight concavity present dorsal to orbit.
Concavity much less pronounced than in more
deep-bodied species. Concavity created by con-
vergence of left and right supraorbital ridges
dorsal to orbit, followed posteriorly by exposed
rising dorsal aspect of supraoccipital crest (nu-
chal spine).
Dorsal-fin origin slightly posterior to vertical
through pelvic-fin origin. Anal-fin origin near
vertical through midpoint of body: approximate-
ly at vertical between last dorsal-fin spine and first
dorsal-fin ray. Caudal peduncle slender and
shallow. Mouth small and terminal, and directed
slightly downward when protruded. Lips some-
what fleshy. Posterior margin of maxilla exposed
and reaching vertical through anterior part of
pupil as well as dorsal portion of lower jaw
articulation. Eye large and circular (29–34% of
head length [HL]). Sensory pores around eye
moderately well developed. One canal on ven-
trocaudal aspect of orbit elongated and reaching
preopercle. Nasal pores closely apposed and
separated by only small bridge of tissue. Both
nasal pores oval; anterior pore roughly half size
of posterior pore. Preopercular margin weakly to
moderately serrated; serrations concentrated
along ventral and ventrocaudal margins. Cerato-
branchial 1 with 13 elongate, triangular, and
heavily denticulated gill rakers. Vertebral count
23 (10 precaudal + 13 caudal). Single supra-
neural present. Supraneural large and robust as
observed through radiographs. Dorsal aspect of
supraneural spine about equal in length to radius
of orbit, whereas vertical (elongate) aspect about
equal to diameter of orbit.
Dorsal fin with eight spines and 16 rays. First
dorsal-fin spine very short (9–11% of length of
second spine). Second dorsal-fin spine longest,
but not considerably longer than third or fourth
spines (Fig. 3). Second, third, and fourth spines
relatively robust, with third and fourth possessing
serrations along their anterior margins that
facilitates interlocking with preceding spines
when fin erect. Remaining spines (V–VIII) more
feeble and shorter. Anal fin with three spines and
14 rays. First anal-fin spine very short (8–10% of
length of second spine). Second and third anal-
fin spines robust, and second only slightly longer
than third. Third anal-fin spine possesses serra-
tions on anterior margin that facilitates inter-
locking with second spine when fin erect. Bases
of spinous portions of both dorsal and anal fins
covered by ridges of tissue lacking scales. Pelvic
fin short and not reaching origin of anal fin
when adducted. Gap between posterior margin
of adducted pelvic-fin and anal-fin origin about
equal to length of pelvic fin. Caudal fin deeply
forked.
Oral teeth long and villiform, and arrayed in
narrow band of four to five rows. Teeth in lower
jaw slightly recurved; those in upper jaw strongly
recurved, almost parallel with roof of mouth.
All specimens comprising type series have lost
most scales in preservation and following ob-
servations should be considered speculative.
Chest, fins, and suborbital series appear asqua-
mate. Scales present in nuchal region and below
dorsal-fin origin in only some specimens. Lateral
Fig. 3. Illustration of holotype of Photoplagios laterofenestra, USNM 387899, adult male, 115.2 mm SL,
Philippines. Pectoral fin not illustrated in order to reveal lateral flank patch. Drawing by Annemarie Noe¨l.
SPARKS AND CHAKRABARTY—NEW SPECIES OF PHOTOPLAGIOS 625
line complete, extending from opercle to poste-
rior margin of caudal peduncle, and comprising
about 60 scales. Lateral line arches only slightly.
Pores of lateral line well developed.
Sexual dimorphism.—Single male specimen, holo-
type, with large translucent patch (guanine-free
region) on anterior flank in shape of cornucopia
(Figs. 3–4). Translucent patch abuts pectoral-fin
base. Translucent patch peppered with aggregat-
ed melanophores and extending longitudinally
from pectoral-fin origin to midpoint of flank.
Ventrally, patch extends to slightly below hori-
zontal through ventral aspect of dentary. Trans-
lucent flank patch lacking entirely in females.
Pigmentation in preservative.—Body generally light
brown above midline. Ventral half of body, from
slightly above midline, covered in silvery guanine.
Gill covers and suborbital region silvery with
guanine extending up to vertical through ante-
rior margin of orbit. Most of area anterior to
vertical through rostral margin of orbit lacks
silvery guanine, except for scattered patches
posteriorly on lower jaw. Dorsal markings ver-
miculate, usually comprising short irregular
patterns; sometimes forming oval shapes dorsally
and anteriorly (Fig. 4). Curved lines present near
lateral line, occasionally appearing as oval
shapes. Dark line present along entire base of
dorsal fin and sometimes extending onto dorsal
margin of caudal peduncle. Dark blotch, due to
concentration of melanophores, present above
upper lip (and sometimes includes upper lip)
ventral to nasal pores, and extending posteriorly
to exposed portion of maxilla. Distinct dark spot
present on prefrontal region posterior to nasal
pores and anterior to orbit. Concentration of
Fig. 4. Photoplagios laterofenestra. (A) Holotype, USNM 387899, adult male, 115.2 mm SL, Philippines.
(B) Paratype, USNM 228508, adult female, 127.9 mm SL, Philippines.
626 COPEIA, 2007, NO. 3
melanophores also present in pectoral-fin axil.
All fins, lips, and interorbital and gular regions
otherwise a pale, opaque gray.
Distribution.—Known only from single lot of
specimens (originally catalogued as USNM
228508) collected from Carigara Bay, Samar
Sea, Philippines.
Etymology.—Named in reference to expansive
translucent lateral flank patch in males (from
the Latin lateralis 5 lateral/side, and fenestra 5
window). Specific epithet, laterofenestra,tobe
treated as a noun in apposition.
D
ISCUSSION
Photoplagios laterofenestra is most similar in
external appearance, including both overall
body shape and pigmentation pattern, to P.
leuciscus and P. klunzingeri. The new species is
distinguished from both P. leuciscus and P.
klunzingeri by a shorter second dorsal-fin spine,
pigmentation pattern on the upper flank (ver-
miculate, with thin wavy lines forming semi-
circles and oval shapes vs. speckled in P. leuciscus
and P. klunzingeri), and the presence of an
expansive cornucopia-shaped translucent flank
patch in males (vs. a triangular patch resem-
bling an inverted pyramid in P. leuciscus and P.
klunzingeri). This translucent patch abuts the
pectoral-fin base broadly (vs. not abutting the
pectoral-fin base in P. leuciscus,orabuttingthe
pectoral-fin base only at the anterior angle of
the triangle in P. klunzingeri; Fig. 1). In addition
to differences in the shape and extent of the
translucent flank patch (Figs. 1, 3–4), P. later-
ofenestra is easily distinguished from both P.
elongatus and P. rivulatus by a deeper body
(34.4–39.2 vs. 12.5–29.7% SL in P. elongatus and
P. rivulatus) and pigmentation pattern on the
upper flank (vermiculate with thin wavy lines
forming semi-circles and oval shapes vs. larger
rounded blotches in P. elongatus and P. rivulatus;
Figs. 1, 3).
A PCA of shape resulted in a PC1 that
accounted for 67% of the variation among the
five species of Photoplagios in which males are
characterized by translucent flank patches. Prin-
cipal component 2 and PC3 accounted for 10%
and 7% of this variation, respectively. The new
species formed a distinct group from all other
species on the plot of PC1 vs. PC2, with the
exception of P. leuciscus for which there was
a slight overlap (Fig. 5). Principal component 1
accounted for much of the variation among
specimens in body depth between the nuchal
area and the anal-fin origin. Principal compo-
nent 1 also accounted for variation in relative
body length among specimens. Principal compo-
nent 2 accounts for some of the variation due to
shortening of the nuchal, snout, and head
TABLE 1. MORPHOMETRIC DATA FOR Photoplagios laterofenestra (n 5 7).
Character Holotype Range Mean SD
Standard length (mm) 115.2 115.2–127.9 120.0
Percentage of SL
Head length 27.4 26.5–29.0 28.2 0.90
Body depth 37.8 34.4–39.2 37.1 1.82
Predorsal length 43.3 42.9–45.5 43.9 0.79
Preanal length 54.9 54.6–59.4 56.3 1.78
Prepelvic length 37.0 37.0–39.4 38.3 0.94
Head width (max.) 13.5 13.2–14.2 13.5 0.36
Caudal peduncle length 8.8 6.1–8.9 8.2 0.95
Caudal peduncle width 3.0 3.0–4.2 3.5 0.39
Caudal peduncle depth 5.5 4.7–6.0 5.2 0.47
Pectoral-fin length 20.1 17.2–20.1 18.3 0.94
Pelvic-fin length 12.3 10.5–13.2 11.6 0.94
Percentage of HL
Snout length 36.4 31.9–37.0 34.7 1.81
Orbit diameter 31.3 28.7–33.7 31.4 1.78
Upper jaw length 43.0 38.7–45.1 40.9 2.61
Lower jaw length 52.8 48.0–58.5 51.0 3.72
Interorbital width 34.8 30.3–38.9 33.5 2.80
Caudal peduncle length/depth 1.6 1.3–1.7 1.58 0.15
Caudal peduncle length/width 2.8 1.5–2.9 2.38 0.48
SPARKS AND CHAKRABARTY—NEW SPECIES OF PHOTOPLAGIOS 627
regions relative to the rest of the body. This
assemblage of five species (including the new
species) is monophyletic and recovered as the
sister taxon to members of the genus in which
males are characterized by a translucent mid-
lateral stripe that is either continuous or com-
prised of numerous discrete windows (Sparks et
al., 2005; Sparks, 2006).
M
ATERIAL EXAMINED
Specimens are listed alphabetically by genus
and species. For each species, type specimens are
listed first (including number in lot), followed
alphabetically by museum abbreviation and in-
cluding number of CS individuals in lot.
Photoplagios elongatus: BMNH 1872.4.6.105,
holotype; CAS 52602; LACM 42993-1; LACM
43584-1; SIO 83-55; USNM 55613; UMMZ
226771; UMMZ 240145, 2 ex. CS; UMMZ uncat.
(PVD 82-06/19a LE).
Photoplagios klunzingeri: NMW 68277, syntypes,
4 ex.; NMW 68280, syntypes, 2 ex.; NMW 76008,
syntypes, 4 ex.; NMW 76009, syntypes, 4 ex.;
AMNH 44488; AMNH 44491; AMNH 44493;
AMNH 44496, 4 ex. CS.
Photoplagios leuciscus: BMNH 1858.4.21.243,
holotype; AMNH 237149; AMS I.22967001; AMS
I.22978004; AMS I.34365015; ANSP 27525, holo-
type of Leiognathus vermiculatus; UMMZ 240125;
USNM 76609; USNM 191979; USNM 191991;
USNM 307917; USNM 373280.
Photoplagios moretoniensis: QM I.1583, syntype, 1
ex.; AMS I.21700001; AMS I.22983001.
Photoplagios rivulatus: RMNH 1438, holotype;
AMNH 34850; UMMZ 182938; UMMZ 240144, 2
ex. CS; UMMZ uncat. (PVD 82-06/19a LR).
Photoplagios stercorarius: USNM 55906, holo-
type; USNM 126395, paratype, 1 ex.; ANSP
33289, paratype, 1 ex.; CAS 42171, paratype, 1
ex.; CAS 17678; CAS-SU 20004, paratype; UMMZ
240138, 2 ex. CS; USNM 191996.
?Photoplagios (Leiognathus) oblonga: MNHN A-
6754, holotype.
?Photoplagios (Leiognathus) parviceps: MNHN A-
0580, syntype, 1 ex.
?Photoplagios sp.: MNHN 1988-0327.
A
CKNOWLEDGMENTS
Thanks to S. Jewett, L. Palmer, K. Murphy, L.
Parenti, and J. Williams (USNM), J. Leis, M.
McGrouther, and T. Trnski (AMS), J. Johnson
(QM), E. Mikschi (NMW), D. Nelson and P.
Dunlap (UMMZ), M. Sabaj and J. Lundberg
(ANSP),H.Walker(SIO),M.vanOijen
(RMNH), and D. Catania and W. Eschmeyer
(CAS) for the loan of specimens in their care. D.
Nelson was extremely helpful with the loan of
material and the curation of specimens deposit-
ed at UMMZ. Thanks to M. Stiassny (AMNH) for
Fig. 5. Principal component analysis of species of Photoplagios in which males are characterized by
a translucent flank patch (plot of PC1 vs. PC2). Photoplagios elongatus specimens are represented by black
dots, P. rivulatus by squares, P. leuciscus by hexagons, P. klunzingeri by triangles, and P. laterofenestra
by diamonds.
628 COPEIA, 2007, NO. 3
providing specimens and to B. Brown, R.
Arrindell, and D. Rodrı´guez (AMNH) for assis-
tance with loans and radiographs. Thanks to M.
Dorsey and A. Nzeribe for assistance with the
collection of morphometric data. We are grateful
to A. Noe¨l for producing the original drawing of
the holotype. This work was supported by a grant
(DEB-0444842) from the National Science Foun-
dation.
L
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DEPARTMENT OF ICHTHYOLOGY,DIVISION OF VERTE-
BRATE
ZOOLOGY,AMERICAN MUSEUM OF NATURAL
HISTORY,NEW YORK,NEW YORK 10024 . E-mail:
( JSS) jsparks@amnh.org; and (PC) prosanta@
amnh.org. Send reprint requests to JSS.
Submitted: 14 Sept. 2006. Accepted: 31 Jan.
2007. Section editor: C. J. Ferraris.
SPARKS AND CHAKRABARTY—NEW SPECIES OF PHOTOPLAGIOS 629