Suruga fundicola Jordan & Snyder, 1901

An, Changting, Li, Ang, Wang, Huan, Li, Busu, Liu, Kaiying, Sun, Hongyue, Liu, Shufang, Zhuang, Zhimeng & van der Laan, Richard, 2023, Identification of the rare deep-dwelling goby Suruga fundicola Jordan & Snyder, 1901 (Gobiiformes, Gobiidae) from the Yellow Sea, Zoosystematics and Evolution 99 (2), pp. 489-501 : 489

Suruga fundicola Jordan & Snyder, 1901

Figs 2 , 3

Suruga fundicola Jordan & Snyder, 1901: 96, fig. 20 (original description, type locality: Sagami Sea, Japan); Akihito et al. 1984: 279 (in English), fig. 253-H; Akihito et al. 2002: 1207 (in Japanese); Akihito et al. 2013: 58 (in Japanese); Shibukawa and Iwata 2013 a: 45; Matsui et al. 2014: 6; Choi and Lee 2019:255, fig. 1.

Diagnosis.

Distinct from all other gobies ( Gobiidae ), members of the Acanthogobius -group share a unique dominant pattern of the dorsal-pterygiophore formula, 3/I II II I I I 0 ( Akihito et al. 1984). In the Acanthogobius -group, S. fundicola can be distinguished from the species of Sagamia , Siphonogobius and Pterogobius by possessing no free rays in the upper part of the pectoral fin and the posterior margin of the pelvic frenum indented. S. fundicola can be distinguished from the species of Lophiogobius , Amblychaeturichthys , and Chaeturichthys by the lack of barbels or flaps on the ventral surface of the head (except for the mental frenum). From species of Acanthogobius , S. fundicola can be distinguished by the large eye, its diameter greater than the snout length (vs. usually less); each cephalic sensory papilla formed into a minute skin flap (vs. not), the posterior oculoscapular canal absent (vs. posterior oculoscapular canal and its terminal pores K’ and L’ present).

Description of Yellow Sea specimens.

The counts and measurements are given in Table 1 . Dorsal-fin rays VIII-I, 16; anal-fin rays I, 15 (1), I, 16 (3); pectoral-fin rays 20 (3), 21 (1); pelvic fin rays I, 5 (4); longitudinal scales 39 (1), 40 (2), 41 (1); pre-dorsal mid-line scales 10 (1), 11 (3); transverse scales 8 (1), 9 (2); 10 (1); vertebral count 14+21 = 35 (4); dorsal-pterygiophore formula 3/I II II I I I 0 i/12; epural 2; anal-fin pterygiophores anterior to first haemal spine 2.

The following measurements are in % SL: head length 24.5-28.0 (mean 26.1); head depth 13.1-17.6 (15.4); head width 13.2-14.2 (13.6); snout length 4.5-5.7 (5.5); eye diameter 8.1-9.7 (8.7); interorbital width 0.9-1.9 (1.4); jaw length 8.3-10.3 (9.0); body width 10.6-10.3 (11.8); body depth at origin of first dorsal fin 15.3-22.4 (18.9); body depth at origin of anal fin 16.0-18.3 (16.9); snout to origin of first dorsal fin 31.5 -33.4 (32.5); snout to origin of second dorsal fin 53.3-58.7 (55.1); snout to origin of anal fin 55.7-61.1 (59.1); caudal peduncle length 10.7-13.5 (11.7); caudal peduncle depth 6.9-8.8 (8.0); pectoral fin length 19.5-21.8 (20.6); base of dorsal fin 13.8-14.7 (14.3); base of second dorsal fin 33.7-36.6 (35.4); base of anal fin 30.2-37.7 (32.4); caudal fin length 19.8-23.3 (21.4).

General body appearance was shown in Figs 2 , 3 . Body small, moderately elongated; predorsal body profile slightly convex; ventral profile slightly concave, especially from pectoral-fin insertion to anal-fin origin. Head large, not depressed, short but longer than wide, depth and width less than those of the body. Snout short, obtuse in lateral and dorsal view, shorter than eye diameter and postorbital head length. Eyes notably large, situated dorsolateral in upper half of the head, with very narrow interorbital space, eyes nearly meeting, diameter larger than interorbital space or snout length. Mouth almost terminal, but upper jaw slightly protruding. Maxillary concealed except at its posterior end. Tongue thick, rather broad, round anteriorly. Gill openings broad, extending anteriorly to the vertical line of the posterior margin of the eye; upper edge of the gill opening on fleshy pectoral-fin base, slightly above the upper margin. No barbels. Body covered with cycloid scales, anterior small, posterior large and the scales are rather loosely attached. Head naked.

Fins flexible, without spinous rays. First dorsal fin with 8 slender spines, reaching origin of second dorsal when depressed; dorsal-pterygiophore formula 3/I II II I I I 0 i/12. Second dorsal fin with 1 simple and 16 branched rays, shorter than the first spines. Origin of first dorsal fin posterior to a vertical through base of pectoral fins, first dorsal fin without filamentous spines. The distal margin of the first dorsal fin is convex, when adpressed, the distal tip touches the base of the spine of the second dorsal fin. Dorsal fins discontinuous. Origin of second dorsal fin somewhat at vertical through the anus, and anterior to the anal fin. When adpressed, the distal tips of the second dorsal fin and the anal fins do not reach the procurrent rays of the caudal fin. Pectoral fins rounded, with 20 rays. The pectoral fin extends posteriorly to the vertical line through the posterior margin of the base of the first dorsal fin. Pelvic fin fused into a disc, each with 1 simple and 5 branched rays. Anal fin with 15-16 rays, the anterior of the anal fin below the third branched dorsal ray of the second dorsal fin. Segmented caudal-fin rays 7+7, upper unsegmented caudal fin rays about 12 and lower unsegmented caudal fin rays about 11.

Cephalic canals are variably developed and are shown in Fig. 4 : anterior oculoscapular canal (AOC) with B′, D (S), F, H’; posterior oculoscapular canal (POC) absent; preopercular canal (PC) with pores M′ and O’; four short longitudinal sensory papillae (SSP) rows (=rows r, u, s, t) on snout; four SSP rows (=rows g, j, k, and l) close behind the eye; two SSP rows (=rows h, i) before dorsal fin; two transverse sensory papillae (TSP) rows (=rows n and o) on snout and behind the eye, respectively; four longitudinal sensory papillae (LSP) rows (=rows a, b, c, and d) on the cheek; anterior end of row a approaches the anterior margin of the eye; rows b and c very close together; row cp with a single sensory papilla; row d arc-shaped, extending posteriorly to the vertical line through the posterior margin of the pupil; two long parallel longitudinal rows of sensory papillae just behind the chin (=row f), and ending on both sides at the opercles, one TSP row (=row ot) and two LSP rows (=rows os and oi) on the opercles, row ot extends to the ventral side.

Cranium flat, frontals extremely narrow (Fig. 5a, e ). No suborbital bone. Five branchiostegal rays, the first one thin, and last one strong (Fig. 5f ). Four pairs of ceratobranchials (Fig. 5g ). Well-developed teeth on upper and lower pharyngeal. Three pairs of otoliths, sagittae, lapillus and asteriscus (Fig. 5e ). Vertebral count 35, 14 abdominal vertebrae (av) and 21 caudal vertebrae (cv), 14 pairs of ribs appending on parapophysis (Fig. 5a, b ). Three hypurals (HY), respectively HY1+2 (HY1 and HY2 fused into one), HY3+4 (HY3 and HY4 fused into one), and HY5; two epurals, EP1 and EP2.

Coloration.

In freshly collected specimens (Fig. 2 ), head and dorsum of body dusky, darker on snout, with several irregular light-yellow blotches on the lateral body, ventral body lighter, abdomen almost white. Pupil of the eye black, iris golden gray. A light sapphirine blotch present on the gill cover. Six or seven large dark spots scattered along middle of the side from the gill opening to the caudal-fin base; 2 or 3 light orange stripes on gray dorsal and caudal fins, the anterior margin of first dorsal fin with dusky spots, the upper posterior of caudal fin with a black stripe, anal fin somewhat gray.

Coloration changed after 2 months of preservation (10% formalin preservative and then transformed to 75% alcohol), the yellow and orange pigment disappeared from body and fins, and the body of the fish became dark-yellowish, covered with tiny black spots, back darker and belly lighter, snout black, lateral dark spots not clear. Pupil of the eye white, iris golden black. Dorsal, pectoral, pelvic and anal fins light greyish.

Distribution.

Northwest Pacific: off Pacific coasts from Miyagi Prefecture to Tosa Bay, Japan Sea from Aomori to Yamaguchi Prefecture, Okinawa Trough ( Akihito et al. 2013), Southern Sea of Korea ( Choi and Lee 2019), East China Sea ( Okiyama 2014) and Yellow Sea (present study).

Habitat and ecology.

The four specimens were collected at depths between 69 and 74 meters (Fig. 1 ). The two stations maintained a relatively low temperature of about 10 °C and a high salinity of about 33‰ in April and July 2022 (Table 3 ). This species is considered as one of the deepest dwelling goby in Japan, known from depths of 40 to 400 meters ( Akihito et al. 2013; Choi and Lee 2019).

The catch at the stations mainly consists of ophiuroids, molluscs, jellyfishes, fishes and so on, most common species of which are the brittle stars Ophiura sarsii vadicola Djakonov, 1954 ( Ophiuroidea) and Stegophiura sladeni (Duncan, 1879) ( Ophiuroidea) (Fig. 6 ). Examples of the co-existing fish species are Jaydia lineata (Temminck & Schlegel, 1843) ( Apogonidae ), Cleisthenes pinetorum Jordan & Starks, 1904 ( Pleuronectidae ), Liparis tanakae (Gilbert & Burke, 1912) ( Liparidae ), Pholis fangi (Wang & Wang, 1935) ( Pholidae ), and Hexagrammos otakii Jordan & Starks, 1895 ( Hexagrammidae ).

Sequence characteristics and phylogenetic placement. The concatenated COI and 12S sequences from 22 species were 704 bp in length (after trimming, except LC069781), including 400 conserved sites, 307 variable sites, 278 parsimony informative sites, and 24 singleton sites. The mean four nucleotide frequency of S. fundicola was A=26.1%, T=28.8%, C=27.3% and G =17.8%, slightly A-T rich (54.9%). The intragroup sequence divergence of S. fundicola was 0.5%; the genetic distance between samples of the Yellow Sea and the sequence (LC069781) of S. fundicola from west of Jogashima Island of Japan was 0.2%. This species has a genetic distance of 19.2% ( C. stigmatias ) to 26.3% ( E. newberryi ) to the other 20 species we used (see Table 4 ). The ML tree based on the concatenated sequences is shown in Fig. 7 . In the tree topology, all species from the same genus clustered in one lineage; the four sequences of S. fundicola clustered into a highly supported (94% bootstrap P value) lineage and had a sister group relationship with the lineage formed by A. hexanema and C. stigmatias .

Material examined.

YSFRI27216-27217, 2 specimens, 51.2-63.5 mm SL, station H27, Yellow Sea , off Qingdao, Shandong Province, China (35°59.69'N, 123°07.63'E), collected by Changting An on 15 April, 2022; YSFRI36942, 1 specimen, 60.5 mm SL, station H12, Yellow Sea, off Lianyungang, Jiangsu Province, China (33°59.88'N, 123°24.14'E), collected by Hongyue Sun, on 16 July, 2022; YSFRI36943, 1 specimen, 59.1 mm SL, station H27, Yellow Sea, off Qingdao, Shandong Province, China (35°56.03'N 123°07.54'E), collected by Hongyue Sun, on 20 July, 2022 .

Figures

Figure 1. Historical distributional records of S. fundicola and the sampling stations. The red full circle 1 indicates the type locality: Sagami Bay (Jordan and Snyder 1901); black arrows 2 and 3 indicate the distribution from Matsushima Bay to Tosa Bay, and black arrows 4 and 5 indicate the distribution from Aomori Prefecture to Yamaguchi Prefectural, black full circle 6 indicates Okinawa Trough (Akihito et al. 2013); blue full circle 7 indicates the records of Tongyeong of South Korea (Choi and Lee 2019); orange full circle 8 and 9 indicate the records in the East China Sea (Okiyama 2014); the green triangles H 27 and H 12 point to the locations of the survey stations where the four goby specimens were caught.

Figure 2. Lateral view of S. fundicola: YSFRI 27216, 63.5 mm SL, photographed alive immediately upon capture.

Figure 3. Lateral (a), dorsal (b), and ventral (c) views of S. fundicola: YSFRI 27216, 63.5 mm SL.

Figure 4. Dorsal (top), lateral (middle), and ventral (bottom) views of the head of S. fundicola: YSFRI 27216, 63.5 mm SL female), showing cephalic sensory canal pores (indicated by roman uppercase letters, except for AN and PN) and papillae (indicated by roman lowercase letters). AN and PN, indicated anterior and posterior nares, respectively.

Figure 5. Micro-CT images of right (a), dorsal (b), and ventral (c) views of specimen YSFRI 27216; front (d) dorsal (e), ventral (f), and oblique view (g) of the head of specimen YSFRI 27216. 1. teeth, 2. premaxilla, 3. maxilla, 4. palatine, 5. ectethmoid, 6. parasphenoid, 7. frontal, 8. parietal, 9. supraoccipital, 10. neural spine, 11. first dorsal fin spines, 12. interdorsal pterygiophores, 13. pterygiophore, 14. second dorsal fin rays, 15. neural spine of preural centrum 3 (NPU 3), 16. neural spine of preural centrum 2 (NPU 2), 17. epural 1 (EP 1), 18. epural 2 (EP 2), 19. urostyle, 20. hypural 5 (HY 5), 21. hypural 3 + 4 (HY 3 + 4), 22. hypural 1 + 2 (HY 1 + 2), 23. dental, 24. articular, 25. sympletic, 26. branchiostegal rays, 27. preopercular, 28. subopercular, 29. proximal radials, 30. pectoral fin soft rays, 31. pelvic fin spine, 32. vertebral canal, 33. boundary of abdominal vertebra and candal vertebrae, 34. anal fin rays, 35. ventrispinales, 36. haemal spine of preural centrum 3 (HPU 3), 37. haemal spine of preural centrum 2 (HPU 2), 38. parhypural (PH), 39. caudal fin ray, 40. rib, 41. parapophysis, 42. pelvic bone, 43. ethmoid, 44. lapillus 3 + 4 (HY 3 + 4), 45. sagittae, 46. asteriscus, 47. basihyal, 48. ceratohyal, 3 (HPU 3). 49. epihyal, 50. cleithrum, 51. pharyngeal tooth, 52. ceratobranchial.

Figure 6. The catch of A: H 27 (15 April), B: H 12 (15 July), and C: H 27 (20 July).

Figure 7. ML tree inferred from concatenated COI and 12 S sequences. Numbers at major internal nodes are bootstrap probability values. Sequences with * were sequenced in the present study.