Indian Lizardfish

Synodus indicus (Day, 1873)

Saurus indicus Day, 1873:526 [India].

Synodus indicus.—Barnard, 1925:227.

Synodus dietrichi Kotthaus, 1967:72 [Somalia].

MATERIAL EXAMINED.—Paralectotype: RMNH 8817 (1), INDIA. RED SEA (21): ZIM 4910. SOMALIA (308): USNM 217606 (1), 217607 (1), 217608 (1); ZIM 4905 (59), 4908 (49), 4909 (197). ZANZIBAR (2): MCZ 6910. INDIA (3): USNM 222059 (2); CAS 14531 (1). SRI-LANKA (2): USNM 217609. THAILAND (5): USNM 217511 (3), 217605 (1), 217610 (1). WESTERN AUSTRALIA (3): WAM P25398-010 (1); AMS (2, uncataloged). PHILIPPINES (1): USNM 218947.

DIAGNOSIS AND COMPARISONS.—A species of Synodus with the following combination of characters: dorsal-fin rays (branched and unbranched) 11–13 (usually 12); anal-fin rays 9–11 (usually 10); pored lateral-line scales 52–58 (usually 56); transverse scale rows 3.5/5; vertebrae 52–58 (usually 56); combined dorsal and anal procurrent rays 27–32; anterior palatine teeth not longest and not in a discrete group; peritoneal spots 9–11; posterior pelvic process wide.

Synodus binotatus, S. capricornis, S. englemani, S. doaki, S. fuscus, S. jaculum, S. hoshinonis, S. ulae, and S. variegatus possess an anterior group of longer palatine teeth. In S. macrops, S. macrocephalus, S. kaianus, S. oculeus, and S. gibbsi, the posterior pelvic process is narrow. The peritoneal spot count of S. fuscus is lower than that of S. indicus (9–11 vs. 7–10). The base of the anal fin of S. sageneus is longer than the base of the dorsal fin; in S. indicus it is not. The peritoneal spot count of S. usitatus is 14–17, whereas in S. indicus it is 9–11. The dermal flap of S. rubromarmoratus is long but of uniform width throughout its length, long and not triangular as in indicus. The dermal flap of S. similis is short and broad (as in hoshinonis).

DESCRIPTION.—Dorsal-fin rays 11–13; anal-fin rays 9–11; pectoral-fin rays 13; pelvic-fin rays 8; procurrent rays 27–32, dorsal 14–17, anal 12–15; lateral line continuous, 52–58 pored scales; scale rows above lateral line from dorsal origin 3.5; scale rows below lateral line to anal origin 5; predorsal scales 14–16; rows of cheek scales 4–5; vertebrae 52–58; peritoneal spots 9–11.

Percentages of Standard Length: Mean (range): head length 29.2(27.0–32.1); snout length 6.7(5.3–7.7); upper jaw length 17.7(16.1–20.1); diameter of bony orbit 5.5(4.0–6.7); least width of bony interorbital 2.5(1.4–3.7); snout to dorsal origin 44.5(41.0–48.4); snout to adipose origin 86.2(82.0–91.1); snout to anal origin 79.2(73.3–85.4); snout to pelvic insertion 37.9(34.3–42.4); snout to pectoral insertion 27.6(25.2–30.6); first-dorsal-ray length 10.7(7.4–13.4); longest-dorsal-ray length 15.9(13.7–19.9); pectoral-fin length 12.6(10.0–14.0); pelvic-fin length 24.2(18.0–27.1); dorsal-fin base 14.3(12.6–16.0); anal-fin base 9.6(7.6–11.9); based on 20 specimens 70.5 to 188.3 mm SL.

Body fusiform, head somewhat depressed, caudal region a little compressed. Large cycloid scales on body, cheeks, and operculum, postoral portion of cheeks scaly. Snout sharply pointed, broader than long; anterior nostril on each side bearing a long triangular dermal flap extending well beyond anterior border of nares when depressed anteriorly. Interorbital space concave, occipital region bony. Palatine teeth in an elongate V- shaped pad, teeth pointing backwardly, those in front not largest and not in a discrete group. Lingual teeth well developed, those on free end of tongue largest and about 40 in number. Teeth caniniform, larger teeth with arrow-shaped tips. Pectoral fins not reaching a line from base of pelvic fins to origin of dorsal fin. Outer pelvic ray unbranched and short, fifth branched ray (sixth ray) longest. Posterior bony process of pelvic girdle broad. Peritoneum pale.

COLOR PATTERN.—Dorsal half of body darker than ventral and somewhat mottled. No distinct pigment pattern in preserved material. Two small black pigment areas at upper distal corner of operculum. Fins unmarked.

DISTRIBUTION, HABITAT, AND GEOGRAPHIC VARIATION.—Synodus indicus occurs throughout the northern Indian Ocean from the Gulf of Aden to the Andaman Sea. South of the equator it has been collected off Zanzibar and off Rawley Shoals, Australia. A single specimen has been collected from the Philippines. Collection data indicate that this species is found at depths of 20 to 100 m (average depth for eight collections 61 m).

Vertebral counts are lowest (52–54) at the easternmost limits of the range (Philippines, W. Australia, Andaman Sea); somewhat intermediate (53–55) in the midportion of the range (India, Sri-Lanka); and highest (55–58) in the westernmost limits of the range (Gulf of Aden, Somalia, Zanzibar). The modal vertebral number (56) based on the material studied may be biased since most of the material examined was from the western portion of the range.

MATERIAL EXAMINED.—Holotype: AMS I.19470-005, Great Barrier Reef, AUSTRALIA. Paratypes: AMS I.18340-001, I.18340-002, I.19222-001, I.19473-054, Great Barrier Reef, AUSTRALIA; AMS I.18303-001, I.19696-004, New South Wales, AUSTRALIA; AMS I.17262-053, PAPUA, NEW GUINEA; AMS I.17503-014, NEW BRITAIN; USNM 217640, COMORES ISLANDS; USNM 217621, SRI-LANKA; USNM 217673, 217748, 217782, SOUTH CHINA SEA; USNM 217794, LINE ISLANDS. Other Material: SOUTH AFRICA (8): RUSI 9214 (3), 10178 (1), 10180 (4). CHAGOS (3): USNM 220540 (1), 220542 (1), 220549 (1). SRILANKA (4): USNM 217625 (2), MCZ 46972 (2). SOUTH CHINA SEA (3): USNM 217752 (1), 217756 (2). TAIWAN (4): USNM 217646 (1), 217647 (1), 217652 (2). MOLUCCAS (1): USNM 210079. CELEBES (7): USNM 217641 (2), 217659 (5). PAPUA, NEW GUINEA (13): USNM 217634 (12), 217638 (1). PALAU (2): CAS 39960 (1), 39961 (1). AUSTRALIA (3): ANSP 123628. KAPINGAMARANGI ATOLL (8): CAS 39956. SOCIETY ISLANDS (6): BPBM 6912 (1), 8334 (2), 11528 (3). MARQUESAS ISLANDS (14): BPBM 11860 (7), 12443 (2), 12641 (1), 12827 (4).

DIAGNOSIS AND COMPARISONS.—A species of Synodus with the following combination of characters: dorsal-fin rays (branched and unbranched) 11–13 (usually 12); anal-fin rays 8–10 (usually 9); pored lateral-line scales 59–62 (usually 61); transverse scale rows 5.5–6.5/9; vertebrae 59–62 (usually 60); combined dorsal and anal procurrent rays 28–33; anterior palatine teeth longest and in a discrete group; peritoneal spots 11–13; posterior pelvic process wide; black pigment spot on caudal peduncle (sometimes lacking on very pale preserved specimens).

Synodus jaculum seems most closely related to S. englemani. It differs from S. englemani by its lack of scales on the postoral portion of the cheeks, higher peritoneal spot count (11–13 vs. 7–10), and its black pigment spot on the caudal peduncle. The posterior pelvic process of S. jaculum is wide (narrow in S. oculeus, S. macrocephalus, S. macrops, S. gibbsi, and S. kaianus). Its vertebral count (59–62) is higher than S. binotatus (51–55), S. indicus (52–58), S. fuscus (53–55), S. hoshinonis (54–57), S. rubromarmoratus (52–55), S. sageneus (49–54). Synodus jaculum has 5.5 scales above the lateral line (S. kaianus, S. similis, and S. usitatus have 3.5. Synodus capricornis has higher vertebral counts (64–65 vs. 59–62). Synodus jaculum has a very short dermal flap on the anterior nares (S. variegatus and S. ulae are long). The black pigment spot on the caudal peduncle, when present, will separate S. jaculum from all known Indo-West Pacific Synodus (the South China Sea specimens are very pale, and the spot is lacking).

DESCRIPTION.—Dorsal-fin rays 11–13; anal-fin rays 8–10; pectoral-fin rays 12–13; pelvic-fin rays 8; procurrent rays 28–33, dorsal 15–18, anal 13–16; lateral line continuous, 59–62 pored scales; scale rows above lateral line from dorsal origin 5.5/6.5; scale rows below lateral line to anal origin 9; predorsal scales 18–22; rows of cheek scales 4–7; vertebrae 59–62; peritoneal spots 11–12.

Percentages of Standard Length: Mean (range): head length 32.1(29.3–35.5); snout length 6.1(5.3–7.2); upper jaw length 19.6(17.7–20.8); diameter of bony orbit 5.6(4.4–6.7); least width of bony interorbital 3.3(2.7–3.9); snout to dorsal origin 44.3(42.1–47.0); snout to adipose origin 85.9(82.8–89.4); snout to anal origin 78.9(76.0–82.0); snout to pelvic insertion 36.4 (34.2–38.3); snout to pectoral insertion 29.9(28.2–31.5); first-dorsal-ray length 10.3(8.6–12.1); longest-dorsal-ray length 15.2(13.1–18.6); pectoral-fin length 11.7(10.3–13.7); pelvic-fin length 25.6(22.0–28.3); dorsal-fin base 15.4(13.4–17.8); anal-fin base 7.6(5.8–9.7); based on 20 specimens 44.9 to 114.0 mm SL.

Body fusiform, head somewhat depressed, caudal region a little compressed. Large cycloid scales on body, cheeks, and operculum, postoral portion of cheeks naked. Snout sharply pointed, broader than long; the anterior nostril on each side bearing a short, triangular flap on its posterior margin, not extending beyond margin of nares when depressed anteriorly. Interorbital space concave, occipital region bony. Palatine teeth in an elongate V-shaped pad, teeth pointing backwardly, those in front largest and in a discrete group. Lingual teeth well developed, those on free end of tongue largest and about 50 in number. Teeth caniniform, form, larger teeth with arrow-shaped tips. Pectoral fins reaching a line from base of pelvic fins to origin of dorsal fin. Outer pelvic ray unbranched and short, fifth branched ray (sixth ray) longest. Posterior bony process of pelvic girdle broad. Peritoneum pale.

COLOR PATTERN.—Preserved specimens with lateral brown saddle-like bands as in S. variegatus. Dark pigmented area usually present on caudal peduncle.

DISTRIBUTION, HABITAT, AND GEOGRAPHIC VARIATION.—Synodus jaculum is apparently a widespread species throughout the Indo-West Pacific. Collection data indicate that it is usually associated with coral reefs, recorded occasionally in shallow water (less than 10 m) but more common at depths of 50–100 m. Specimens with 6.5 scales above the lateral line were from the Line Islands.