Species Diversity 17: 123–126
25 November 2012

Epigonus merleni, a Junior Synonym of Epigonus macrops(Actinopterygii: Perciformes: Epigonidae)
Makoto Okamoto1,4, Peter Bartsch2 and Hiroyuki Motomura3
1 Seikai National Fisheries Research Institute, 1551-8 Taira-machi, Nagasaki 851-2213, Japan

E-mail: okamako@affrc.go.jp

2 Museum für Naturkunde, Leibniz Institute for Research on Evolution and Biodiversity, Humboldt University Berlin,

Invalidenstr. 43, D-10115 Berlin, Germany

3 The Kagoshima University Museum, 1-21-30 Korimoto, Kagoshima 890-0065, Japan
4 Corresponding author(Received 4 July 2012; Accepted 4 September 2012)
Epigonus merleni McCosker and Long, 1997 was originally described on the basis of a single specimen collected fromthe Galápagos Islands. It was considered to be distinguished from E. macrops (Brauer, 1906) by having 11+14 vertebrae and57 lateral-line scales, but our examination of the holotype of E. merleni revealed that it actually has 10+15 vertebrae and48+5 lateral-line scales. The holotype also has a luminescent window near the pelvic-fin base that is otherwise unique toE. macrops in the genus. Based on our comparison of the holotype of E. merleni with a syntype and other specimens of E.
macrops, we conclude that E. merleni is a junior synonym of E. macrops.
Key Words: Teleostei, deepwater cardinalfish, Epigonus, synonymy.

Introduction
Epigonus merleni McCosker and Long, 1997 was originally described from a single specimen collected on the sea
surface during the 1995 eruption of Fernandina Volcano in
the Galápagos Islands. According to McCosker and Long
(1997), this species belongs to the “E. telescopus group“ (sensu Abramov 1992) in having eight spines on the first dorsal
fin. McCosker and Long (1997) distinguished their new species from the other four species of the group by its five pyloric caeca, 17 pectoral-fin rays, nine soft rays in the second
dorsal fin, and 11+14 vertebrae. Our examination of thetype specimen of E. merleni revealed that the original description did not accurately report several important characters. Comparison with other congeners has subsequently
led us to conclude that E. merleni is a junior synonym of
Epigonus macrops (Brauer, 1906).

Materials and Methods
Methods for enumerating meristic and morphometriccharacters follow Mayer (1974) except for body depth andbody width, for which we follow the definitions of Okamoto (2011). Missing lateral-line scales were estimated bycounting scale pockets. The number of pored lateral-line
scales on the caudal fin is represented as “+n”. Definitionof the first caudal vertebra follows Okamoto and Motomura(2011). Counts of vertebrae and ribs were taken from radiographs. The presence of a ventral luminescent window, thenumber of pyloric caeca, and sex were established by dissection of the abdomen on the right side. Standard length isabbreviated as SL. Institutional abbreviations for the depositories of the examined specimens are: AMS, Australian Museum, Sydney; CAS, California Academy of Sciences, SanFrancisco; HUMZ, Hokkaido University Museum, Hakodate; MCZ, Museum of Comparative Zoology, Harvard University, Cambridge; NSMT, National Museum of Nature andScience, Tsukuba; TCWC, Texas A&M University, CollegeStation, Texas; USNM, Smithsonian Institution National
Museum of Natural History, Suitland; and ZMB, Ichthyology, Zoologisches Museum, Museum für Naturkunde, Berlin.
Material examined. Epigonus macrops (13 specimens): ZMB 17678, syntype, 202.5 mm SL, 03°22′01″S,101°11′05″E, western coast of Sumatra, Indonesia, eastern
Indian Ocean, 903 m depth, 21 January 1899; CAS 86581,holotype of E. merleni, 139.1 mm SL, 00°28′S, 91°37′W, surface offshore of Cabo Hammond, Isla Fernandina, Galápagos Islands, eastern Pacific, February 1995; AMS I. 22814018, 131.6 mm SL, 18°48′00″S, 116°60′00″E, northwest ofPort Headland, Australia, Indian Ocean, 704 m depth, 6April 1982; AMS I. 31161-004, 170.5 mm SL, 24°53′67″S,111°80′83″E, off Cape Cuvier, Australia, Indian Ocean,
901 m depth, 28 January 1991; CSIRO H 2562-01, 178.4 mm
SL, 24°28′S, 111°51′E, west of Quobba Point, Australia, Indian Ocean, 905 m depth, 28 January 1991; CSIRO H 657508, 126.8 mm SL, 14°35′S, 121°21′E, northwest of Cape
Leveque, Australia, Indian Ocean, 709 m depth, 26 June2007; MCZ 48827, 148.7 mm SL, 11°54′N, 69°18′W, Caribbean Sea, 910 m depth, 4 October 1963; TCWC 6372.09, 4specimens, 103.7–145.6 mm SL, 27°64′N, 91°53′W, Gulfof Mexico, 731 m depth, 3 March 1986; TCWC 7003.10, 2specimens 120.6–156.7 mm SL, 27°14′N, 93°39′W, Gulf ofMexico, 792–864 m depth, 8 April 1986.
Comparativematerials. Epigonusangustifrons© 2012 The Japanese Society of Systematic Zoology

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Makoto Okamoto et al.

Fig. 1. Photographs of Epigonus macrops. A, holotype of E. merleni (CAS 86581, 139.1 mm SL); B, syntype of E. macrops (ZMB 17678,202.5 mm SL).

Fig. 2. X-ray photographs of Epigonus macrops. A, holotype of E. merleni (CAS 86581, 139.1 mm SL); B, syntype of E. macrops (ZMB
17678, 202.5 mm SL).

Abramov and Manilo, 1987: HUMZ 99978, 216.0 mm SL,26°09′S, 06°21′E, eastern South Atlantic, 246 m depth, 10March 1983. Epigonus notacanthus Parin and Abramov,
1986: HUMZ 166513, 107.6 mm SL, 25°33′S, 87°15′W, Nazca Ridge, eastern South Pacific, 11 October 1999; HUMZ
166519, 90.7 mm SL, data same as HUMZ 166513. Epigonus
telescopus (Risso, 1810): AMS I. 28165-001, 3 specimens,112.4–187.9 mm SL, 33°35′17″S, 44°09′33″E, Walters Shoal,southwestern Indian Ocean, 750 m depth, 18 December
1988; USNM 307603, 201.2 mm SL, 33°43′42″S, 43°61′58″E,
Walters Shoal, southwestern Indian Ocean, 1,000–1,030 mdepth, 17 December 1988; USNM 307608, 2 specimens,
137.8–154.3 mm SL, 33°37′42″S, 44°10′42″E, Walters Shoal,
southwestern Indian Ocean, 750–775 m depth, 18 December
1988.

The synonymous Pacific epigonid fishes

125

Table 1. Selected counts and measurements of specimens of Epigonus macrops, including the holotype of E. merleni and a syntype of E.
macrops.
E. merleniStandard length (mm)Counts
Dorsal-fin rays
Anal-fin rays
Pelvic-fin rays
Pored lateral-line scales
Gill rakers
Vertebrae
Measurements (% standard length)
Head length
Head height
Body depth
Body width
Caudal-peduncle depth
Caudal-peduncle length
Orbital diameter
Interorbital width
Postorbital length
Upper-jaw length
Lower-jaw length
Snout lengthPre-1st dorsal-fin lengthPre-2nd dorsal-fin length
Pre-pectoral-fin length
Pre-pelvic-fin lengthPre-anus lengthPre-anal-fin length
1st spine length on 1st dorsal fin
2nd spine length on 1st dorsal fin
3rd spine length on 1st dorsal fin
2nd dorsal-fin spine length
1st anal-fin spine length
2nd anal-fin spine length
Pelvic-fin spine length
1st dorsal-fin base
2nd dorsal-fin baseAnal-fin base
Pectoral-fin length
Pelvic-fin length

E. macrops

CAS 86581

ZMB 17678

Other specimens

Holotype

Syntype

n=11

139.1

202.5

103.7–178.4

VII-I-I, 10II, 9
1948+54+15=1910+15

VII-I-I, 10II, 9
1851+54+15=1910+15

VII-I-I, 10II, 9
18–19
44–51+2–5
4–5+13–15=18–20
10+15

36.7
18.6
24.2
17.3
10.4
26.1
15.3
10.9
14.2
14.0
17.3
7.9
36.9
57.3
35.5
36.0
59.0
64.4
2.2
12.4
14.1
7.5
1.4
7.6
13.5
14.3
10.6
9.3
21.2
15.8

37.8
17.8
23.2
17.7
10.7
24.5
14.3
12.0
14.4
14.3
17.0
9.4
40.0
60.1
39.3
41.6
61.4
68.3
Tip broken
14.1
14.5
6.0
Tip broken
7.7
13.5
11.5
9.8
9.7
20.7
15.7

34.6–37.8
17.4–20.2
20.8–24.3
14.0–17.7
8.9–10.9
24.4–28.9
12.7–17.5
10.2–11.5
12.3–14.6
13.3–14.8
15.9–19.3
6.7–9.5
36.8–40.1
57.0–60.3
35.2–39.5
35.8–41.7
57.0–61.7
64.3–69.4
1.2–2.8
11.5–15.9
12.3–15.7
4.9–7.8
1.2–2.7
4.8–8.8
11.7–14.8
10.8–16.0
9.6–11.3
9.3–10.9
16.7–21.3
14.9–16.0

Results and Discussion
McCosker and Long (1997) referred E. merleni to the E.
telescopus group (sensu Abramov 1992) based on the presence of eight spines in the first dorsal fin. According toAbramov (1992) and Okamoto (2012), this species group
comprises four species besides E. merleni: E. angustifrons,E. macrops, E. notacanthus, and E. telescopus. McCosker andLong (1997) stated that E. merleni is distinguishable fromthree species of this group in having 11+14 vertebrae (thesame number as in E. telescopus vs 10+15 vertebrae in E.
angustifrons, E. macrops, and E. notacanthus); however, ourexamination of the holotype of E. merleni revealed the vertebral number to be 10+15 (Fig. 2). There are no clear differences in other meristic and morphometric characters between this holotype and the examined specimens, including
a syntype of E. macrops (Table 1). In addition, we confirmed
the presence of a luminescent window near the pelvic-fin
base in the holotype of E. merleni (Fig. 3). Mayer (1974)
considered a ventral luminescent organ to be unique for E.
macrops within the genus. Accordingly, the holotype of E.
merleni is considered to be a specimen of E. macrops, andthe former nominal species is reduced to a junior synonymof E. macrops.
In addition to the above-mentioned characters, the126Makoto Okamoto et al.

of the holotype of E. merleni. Although McCosker and Long(1997) described E. merleni as having the greatest numberof pored lateral-line scales (57) in the genus, in the holotype
we found only 48 pored lateral-line scales to the end of thehypural, plus 5 pored lateral-line scales on the caudal fin.

Acknowledgments
We are especially grateful to T. Iwamoto (CAS) for providing valuable data on the holotype of E. merleni and forhis critical reading of this manuscript. We also thank M.
McGrouther (AMS), A. Graham (CSIRO), M. Yabe and T.
Kawai (HUMZ), K. Hartel (MCZ), K. W. Conway and H. L.
Prestridge (TCWC), and J. Williams and E. Wilbur (USNM)
for loans of comparative specimens.

References
Fig. 3. External (A) and internal (B) views of the ventral regionof the holotype of Epigonus merleni (CAS 86581, 139.1 mm SL). Arrows point to the luminescent window, covering a large scale in A.
Scale bars: 5 mm.

dorsal- and anal-fin ray counts and the number of lateral-line scales reported by McCosker and Long (1997) forE. merleni are erroneous. Although these authors presented the count as “dorsal rays VIII+I, 9”, the holotype of E.
merleni has seven spines in the first dorsal fin, an isolated spine between the first and second dorsal fins, and one
spine and ten soft rays in the second dorsal fin (expressedas VII-I-I, 10). Our examination of the other species of theE. telescopus group showed that the first dorsal fin of all species comprises seven spines connected by a fin membrane,plus an eighth isolated spine. A number of authors (e.g.,Mayer 1974; Abramov and Manilo 1987; Abramov 1992)
have misconstrued the condition of the first dorsal fin andgiven the spine count as VIII. Abramov (1992) consideredthat count a unique diagnostic character for the E. telescopus group. McCosker and Long (1997) also stated that theanal fin has one spine rather than two as in other species ofEpigonus. We confirmed there are two spines in the anal fin

Abramov, A. A. 1992. Species composition and distribution of Epigonus (Epigonidae) in the world ocean. Journal of Ichthyology 32:
94–108.
Abramov, A. A. and Manilo, L. G. 1987. Epigonus angustifrons sp. n.,
a new cardinal fish (Perciformes, Apogonidae) from submarine
mountain ridges in the subtropical zone of the Indian Ocean.
Byulleten Moskovskogo Obshchestva Ispytatelei Prirody. Otdel Biologicheskii 92: 45–48. [In Russian]
Mayer, G. F. 1974. A revision of the cardinalfish genus Epigonus (Perciformes, Apogonidae), with descriptions of two new species. Bulletin of the Museum of Comparative Zoology 146: 147–203.
McCosker, J. E. and Long, D. J. 1997. A new species of the deepwater
cardinalfish Epigonus (Perciformes: Epigonidae) from the Galápagos Islands. Ichthyological Research 44: 125–129.
Okamoto, M. 2011. A new species of deepwater cardinalfish, Epigonus
mayeri, from the eastern Central Atlantic, and redescription ofEpigonus heracleus Parin and Abramov 1986 (Perciformes: Epigonidae). Ichthyological Research 58: 101–108.
Okamoto, M. 2012. Two new species of the genus Epigonus (Perciformes: Epigonidae) from the South Pacific, with a definition ofthe Epigonus constanciae group. Ichthyological Research 59: 252–254.
Okamoto, M. and Motomura, H. 2011. Epigonus carbonarius, a newspecies of deepwater cardinalfish (Perciformes: Epigonidae) from
the Marquesas Islands, with a redefinition of the Epigonus oligolepis group. Ichthyological Research 58: 155–160.