Synodus autumnus, Furuhashi & Motomura, 2025

Furuhashi, Ryusei & Motomura, Hiroyuki, 2025, Synodus autumnus, a new species of lizardfish (Aulopiformes, Synodontidae) from the Indo-Pacific region, and a reassessment of distributional records of Synodus rubromarmoratus, ZooKeys 1243, pp. 191-206 : 191-206

Synodus autumnus sp. nov.

Figs 1 , 2 , 3 , 4 , 5 , 7 , Table 1 New English name: Autumn Lizardfish; new standard Japanese name: Iroha-eso

Synodus ulae (not of Schultz): Mochida and Motomura 2018: 8 (San, Tokuno-shima island, Amami Islands, Japan).

Synodus cf. rubromarmoratus : Honda et al. 2024: 141 (east coast of Izu Peninsula, Sagami Bay, Japan).

Material examined.

Holotype. • KAUM –I.180000 ( LC 859381 ), 54.2 mm SL, off Segaura , Kushi , Bonotsu, Minami-satsuma, southwest coast of Satsuma Peninsula, Kagoshima Prefecture, southern Kyushu , Japan, 5 m depth, hand net, 2 Feb. 2023, coll. by M. C. Sato . Paratypes. 34 specimens, 15.8–96.5 mm SL. Japan: • KAUM –I.82280 ( LC 859380 ), 58.3 mm SL, San , Tokunoshima , Tokuno-shima island, Amami Islands, Kagoshima Prefecture, 1–18 m, hand net, 25 Nov. 2015, H. Motomura, D. Uyeno, H. Uyeno, Y. Fukui, K. Eguchi and A. Yoshiura ; • KPM -NI 32554 , 40.6 mm SL, Izu Oceanic Park , Jogasaki Coast, east coast of Izu Peninsula (Sagami Bay), Shizuoka Prefecture, 16 Dec. 1989, H. Masuda ; • KPM -NI 43326 , 45.8 mm SL, Izu Oceanic Park , Jogasaki Coast, east coast of Izu Peninsula (Sagami Bay), Shizuoka Prefecture, 27 m, 5 Jan. 2017, W. Takase . Taiwan: • ASIZP 59174 , 96.5 mm SL, Liuqiu Island , Pingtung, 23 Apr. 1984, K. - T. Shao . Philippines: • BPBM 22462 , 2 specimens, 48.9–50.1 mm SL, Caban Island , Batangas Province, Luzon, 30 m, 28 July 1978, J. E. Randall, G. W. Tribble, R. P. H. Rutherford and K. E. Carpenter ; • USNM 436037 ( OQ 387399 ), 57.2 mm SL, off coastline south of Escarceo Point , Puerto Galera, Oriental Mindoro, 12–18 m, 2 Apr. 2015, J. Williams, D. Catania and R. Betancur ; • USNM 436288 ( OQ 387293 ), 68.8 mm SL, Puerto Galera , Oriental Mindoro, 23–26 m, 16 Apr. 2015, J. Williams, D. Catania and D. Dumale . Palau: • BPBM 9363 , 4, 15.8–59.7 mm SL, Ulebsechel Island , 15.2 m, 16 Apr. 1970, J. E. Randall, A. R. Emery et al . Marshall Islands: • BPBM 39704 , 45.4 mm SL, Bigej-Meck Reef , Kwajalein Atoll, 25 m, 29 Dec. 2004, B. D. Greene . Indonesia: • BPBM 32414 , 67.8 mm SL, east of Toro Liu Point , Komodo, 26–28 m, 16 Oct. 1987, J. E. Randall and E. Clark ; NSMT -P 106331 , 52.9 mm SL, coral reef between Meno and Air islands , Lombok, Indonesia, 10 m . Timor-Leste: • AMS I.46120-005 , 2, 54.4–73.4 mm SL, halfway between Hera and Metinaro, 150 m off shore , 12 m, 23 Sept. 2012, M. A. McGrouther, S. E. Reader, A. Hay, J. M. Leis, B. C. Russell and P. B. Berents . Papua New Guinea: • AMS I.33751-019 , 45.7 mm SL, Portlock Reef , 5–31 m, 29 Jan. 1993 ; NTM S.13661-036 , 3, 42.0– 64.4 mm SL, Madang, 18–22 m, 5 Oct. 1992, H. K. Larson and M. Jebb . Australia: • AMS I.19223-001 , 3, 57.4–73.0 mm SL, One Tree Island , Queensland, 30–33 m, 14 Sept. 1974, B. C. Russell ; • AMS I.30310-030 , 7, 25.7–71.0 mm SL, North Solitary Island , New South Wales, 12–14 m, 5 May 1977 ; NTM S.11389-040 , 44.9 mm SL, north east side of Scott Reef North , Western Australia, 7–10 m, 13 Sept. 1984, B. C. Russell . Tonga: • AMS I.46738-107 , 83.2 mm SL, Vaka'eitu Island , Vava’n Group, 10–19 m, 13 Jan. 2015, S. E. Reader, N. Jolly, I. Middleton and T. Trnski ; • AMS I.46739-034 , 41.5 mm SL, north east of O’ua Island , Ha’apai Group, 13–16.5 m, 14 Jan. 2015, S. E. Reader, N. Jolly, I. Middleton, T. Trnski, R. Robinson and C. Bedford .

Diagnosis.

A new species of Synodus with the following combination of characters: Dorsal-fin rays 11–13; anal-fin rays 8–10; lateral-line scales 49–51; scale rows above lateral line 3.5; scale rows below lateral line 4.5; vertebrae 49–52; anterior gill rakers 22–29; peritoneal spots 0–5; anterior palatine teeth in a discrete group, longer than posterior palatine teeth; ANF long and broad, leaf-like, extending above and behind posterior margin of posterior nostril when laid back; posterior process of pelvic girdle wide; posterior part of preopercle scaled; body with 5 reddish saddle-like blotches; lateral surface below lateral line with a straight row of brown blotches when fresh.

Description.

Data for holotype presented first, followed by paratype data in parentheses (if different). Counts and measurements in Table 1 . Characters given in diagnosis not repeated.

Body elongate, cylindrical, body depth greatest at pelvic-fin origin. Scales moderately large, cycloid, not deciduous, present on cheek and opercle. Cheek fully scaled, 5 (4–7) vertical scale rows, becoming progressively smaller posteriorly. Pre-dorsal-fin scales not reaching a vertical line of posterior edge of orbit. No scales on dorsal, anal, adipose, and paired fins. Caudal fin with large, pointed scales on each lobe, not reaching margin of fin fork. Procurrent caudal-fin rays without scale covering.

Snout moderately pointed in dorsal view. Two nostrils, about equal size, close to each other, located on a line connecting anteriormost margin of orbit and snout tip, close to front of orbit, anterior nostril with a dermal flap on posterior margin. Posterior nostril moderately narrow, almost directly behind anterior nostril. Internarial distance about equal to posterior nostril diameter. Eye circular, directed laterally. Interorbital region broad, with slight V-shaped concavity in front view.

Mouth large, terminal, slightly oblique, gape almost reaching posterior margin of preopercle. Teeth on both jaws numerous, small, needle-like, generally two rows on upper jaw and three rows on lower jaw, outer teeth smaller, inner teeth longer, covered by lip, tip of upper jaw teeth visible, base of jaw teeth hidden when mouth closed. Palatine teeth in 2 rows anteriorly, 2 (2 or 3) posteriorly, outer row teeth long, tooth rows close together anteriorly but slightly separated. Vomerine teeth absent. Tongue short, spatulate, fleshy, with about 33 (29–50) posteriorly depressible teeth, forming a rectangular teeth patch, 5 (5 or 6) rows on posterior region. Lower-jaw length similar to upper jaw, its anterior end fitting into groove between teeth on upper-jaw tip. Gill rakers very small, unobtrusive, plate-like, with numerous tooth-like spines.

Dorsal-fin origin just behind to midpoint between snout and adipose-fin origin, dorsal-fin base longer than anal-fin base, first and second rays unbranched, second (second or third) ray longest, posterior rays gradually shorter. Adipose fin small, above midpoint of anal-fin base. Anal fin short, posteriormost ray branched to base, others unbranched, third (second or third) ray longest, remaining rays subequal. Anus just anterior to anal-fin origin. Pectoral and pelvic fins with moderately long axillary scales at bases. Pectoral fin rounded, extending beyond P – D line, uppermost ray unbranched. Pelvic fin longer than pectoral fin, sixth ray longest, innermost (eighth) ray distinctly longer than outermost (first) ray. Caudal fin forked, lobes moderately pointed, dimensions of upper and lower lobes symmetrical.

Color in fresh specimens (Figs 1 , 2 ). Body above lateral line orangish-brown (orangish or yellowish-brown), below white. Five brown blotches along lateral line connecting to reddish saddle-like blotches edged blueish-white. Blotch above pectoral-fin base indistinct. A row of distinct brown blotches and two rows of white blotches on ventrolateral surface. Head red above maxilla, dark brown (dark brown or yellowish-green) below lower jaw. Snout tip with (with or without) a pair of dark spots. Iris orangish-red (orangish-red or yellowish-orange). All fins with reddish bars, membrane uniformly translucent.

Color in preserved specimens (Fig. 3 ). Most fresh colors lost. Body pale, except dorsum. Dorsal surface dark, areas of saddle-like blotches (when fresh) white. Lower jaw with (with or without) black pigmentation. Snout tip with (with or without) a pair of dark spots. All fins unpigmented. Peritoneum pale.

Distribution and habitat.

Synodus autumnus sp. nov. is widely distributed in the eastern Indian and Pacific oceans, from Japan, Taiwan, the Philippines, Palau, the Marshall Islands, Indonesia, Timor-Leste, Papua New Guinea, Australia, Tonga, and the Hawaiian Islands (Fig. 4 ). It inhabits inshore areas with coral or rocky reefs and boulders, at depths of 1–33 m (Fig. 5 ).

Etymology.

Scientific and English names of the new species are derived from its body color, which is reminiscent of shrub and tree colors that change in autumn. “ Iroha ” means the leaves of plants that change color in autumn.

Remarks.

The peritoneal spots of Synodus are not usually lost in species of Synodus , but in S. autumnus and S. binotatus , they peel off easily, making accurate counting difficult. Although this characteristic is limited to the latter two species, the peritoneal spots may be lost in examples of other species if the abdomen has decayed (Furuhashi unpubl. data).

Figures

Figure 1. Fresh holotype of Synodus autumnus sp. nov. (KAUM – I. 180000, 54.2 mm SL, Segaura, Kushi, Bonotsu, Minami-satsuma, Satsuma Peninsula, southern Kyushu, Japan). A. Lateral view; B. Dorsal view; C. Ventral view.

Figure 2. Fresh paratypes of Synodus autumnus sp. nov. A. KAUM – I. 82280, 58.3 mm SL, Japan; B. KPM - NI 43326, 45.8 mm SL, Japan, photo by H. Senou.

Figure 3. Preserved specimens of Synodus autumnus sp. nov. A – C. KAUM – I. 180000, holotype, 54.2 mm SL, Japan; D. KAUM – I. 82280, paratype, 58.3 mm SL, Japan; E. USNM 436037, paratype, 57.2 mm SL, the Philippines. A, D, E. Lateral view; B. Dorsal view; C. Ventral view.

Figure 4. Distributional records of Synodus autumnus sp. nov. (red star, closed and open circles indicate holotype, paratypes and genetic sample, respectively) and Synodus rubromarmoratus (green triangle indicates type locality).

Figure 5. Underwater photograph of holotype of Synodus autumnus sp. nov. (KAUM – I. 180000, 54.2 mm SL) just before collection at a depth of 5 meters off Segaura, Satsuma Peninsula, southern Kyushu, Japan. Photo by M. C. Sato.

Figure 7. Neighbor-joining phylogenetic tree of Synodus autumnus sp. nov., S. binotatus and S. cf. autumnus based on COI sequences (598 bp). Support values (≥ 50 ML bootstrap probability) indicated along branches.