Hippocampus sindonis Jordan & Snyder, 1901

Han, Sang-Yun, Kim, Jin-Koo, Kai, Yoshiaki & Senou, Hiroshi, 2017, Seahorses of the Hippocampuscoronatus complex: taxonomic revision, and description of Hippocampushaema, a new species from Korea and Japan (Teleostei, Syngnathidae), ZooKeys 712, pp. 113-139 : 119-122

Hippocampus sindonis Jordan & Snyder, 1901 Figs 3H I, 4C, 5D E, 6C, 6F, Tables 2, 3

Hippocampus sindonis Jordan and Snyder 1901: 17, pl. 11 (Holotype: USNM 49730; type locality: Totomi bay, off Hamamatsu, Totomi Province, Shizuoka, Japan); Jordan et al. 1913: 100; Matsubara 1955: 431; Araga 1984: 89; Lourie et al. 1999: 119; Mukai et al. 2000: 139; Senou 2000: 536; Senou 2002: 536, 1508; Lourie et al. 2004: 74; Yoshino and Senou 2008: 76; Kuiter 2009: 131; Senou 2013: 635, 1911; Lourie 2016: 108; Lourie et al. 2016: 39.

Hippocampus coronatus : Burgess and Axelrod 1972: 211; Araga 1984: 89; Senou 1993: 489 (left fig.), 1294 (non Temminck & Schlegel).

Hippocampus mohnikei : Jordan and Snyder 1901: 18; Jordan et al. 1913: 98; Boeseman 1947: 196; Matsubara 1955: 431; Burgess and Axelrod 1972: 210; Araga 1984: 89 (non Bleeker).

Hippocampus japonicus : Burgess and Axelrod 1972: 211 (non Kaup).

Material examined.

Japan. USNM 49730 (holotype of H. sindonis , photograph and radiograph from USNM), male, 49.1 mm SL, Totomi bay, off Hamamatsu, Totomi Province, Shizuoka, dredged by the U.S. Fish Commission Steamer Albatross ( Jordan and Snyder 1901). RMNH.PISC 3924 (photograph from RMNH), 1 female, 74.0 mm SL. FAKU 121388, 1, 69.4 mm, Tanabe, Wakayama, Jan 1969. FAKU 137339, 1 93.0 mm, Hozaura, Minami-ise, Watarai, Mie, depth 20 25 m, Nov 2014, H. Sugawara. FAKU 137340, 1, 95.9 mm, Nayaura, Minami-ise, Watarai, Mie, depth 25 30 m, Mar 2014, H. Sugawara. KPM-NI 19257, 1, 59.4 mm SL, 16 May 1999, D. Sugita; KPM-NI 19258, 1, 44.4 mm SL, 18 Oct 1997, M. Kojima; KPM-NI 19259, 1, 30.1 mm SL, 5 Jul 1998, T. Kamano; KPM-NI 19261, 1, 43.3 mm SL, 7 Aug 1998, N. Ogata; KPM-NI 19262, 1, 32.2 mm SL, 25 Aug 1998, N. Ogata; Kannonzaki, Tatara-hama, Obaradai, Yokosuka, Kanagawa. KPM-NI 19475, 1, 82.1 mm SL, 23 Sep 2007 K. Okubo; KPM-NI 19797 19798, 2, 75.1 99.8 mm SL, 18 Oct 2007, K. Okubo; KPM-NI 21947, 1, 75.4 mm SL, K. Okubo; Manatsuru, Ashigarashimo, Kanagawa.

Diagnosis.

A species of Hippocampus having a bony body; double gill openings; R 10 + 35 38 (holotype: 10 + 37); coronet moderately high; CoT 5; CHGO 26.8 41.0 % HL; CHMC 36.3 55.4 % HL; a very blunt or truncated spine on the dorsal fin base; no WS on dorsal fin base.

Description.

Head and trunk folded at approximately right angle; snout elongated and fused; pelvic and caudal fins absent; prehensile tail; D 11 15, mode 12 (holotype: 15); A 4; P 11 14, mode 11 (holotype: 14); D always greater than or equal to P; CS 1; ES 2 (anterior ES smaller than posterior ES); SnL 28.7 37.2 % HL; ED 41.5 69.0 % SnL; HL 57.2 80.1 % TrL; TrL 38.3 52.1 % TaL; coarse skin often covering armor-plated body; moderately high coronet; CoT, 5; body spines blunt, truncated, or absent; spines on 1st, 4th, 7th, and 10thTrR more prominent than on other TrRs, except for the lateral spine on the 10thTrR; several skin filaments on ACS and ES, and prominent TrR and TaR spines, or skin filaments absent on these structures; variable coloration on fresh specimens, including white, red, yellow, brown, and grey; variable patterns on fresh specimens, often presenting white radial blotches on iris and surrounding eye, stripes and/or blotches on body, and, occasionally, a semicircular stripe on dorsal fin; preserved specimens, black, pale white, brown, or grey; no sexual dimorphism apart from male brood pouch.

Distribution.

Southeastern coast of Honshu (Japan), from Tanabe (Wakayama Prefecture) to Boso Peninsula (Chiba Prefecture) (Fig. 1). Hippocampus sindonis lives in a wide range of habitats, from shallow high-energy algae reefs to soft bottom habitats ( Kuiter 2009), at 2 30 m depth ( Senou 2013).

Etymology.

The specific name sindonis was derived from the name of M. Sindo, an assistant curator of fishes at Stanford University ( Jordan and Snyder 1901; Lourie 2016). The English name was coined by Kuiter (2009). The Japanese name Hanatatsu literally means hana (flower or blossom, which indicates gorgeous) + tatsu (dragon, or the abbreviation of the word Tatsu-no-otoshigo: seahorse), and refers to the beautiful color and skin filaments of the species.

Remarks.

The 14 Japanese specimens of H. sindonis have a moderately high coronet with five CoT, and a couple of prominently blunted or truncated spines on the dorsal fin base, therefore corresponding to the description and holotype of H. sindonis provided by Jordan and Snyder (1901). In the 12S rRNA tree, our H. coronatus specimens (voucher number: FAKU 137348 137351) appeared in the same clade as Mukai et al.'s (2000) high coronet specimen (GenBank accession number AB032030) whereas our H. sindonis specimens (voucher numbers FAKU 137339 137340) formed a clade with Mukai et al.'s (2000) low coronet specimen (accession number AB032029) (Fig. 7B). Hippocampus sindonis is considered the most external group within the H. coronatus complex because of its homogenous CoT (= 5) and no WS, as found in H. coronatus complex outgroups (e.g., H. mohnikei and H. trimaculatus ).

RMNH.PISC 3924 was labeled Hippocampus fasciatus Kaup 1853 ( Boeseman 1947), which is a nomen nudum in Hippocampus . Boeseman (1947) noted that RMNH.PISC 3924 was related to H. coronatus and H. mohnikei , and that its morphology agreed with Jordan and Snyder s (1901) description as well as with Bleeker s (1853) H. mohnikei specimens. However, we found that Bleeker s H. mohnikei (RMNH.PISC 7259, 3 specimens) differ from RMNH.PISC 3924 in their TrR number (11 in Bleeker s specimens vs. 10 in RMNH.PISC 3924). Thus, RMNH.PISC 3924 belongs to the H. coronatus complex, and its ES 2 and coronet features (moderately high coronet with 5 CoT) allow identifying it as H. sindonis . Jordan and Snyder (1901) stated that H. sindonis was distinguished from H. mohnikei by dorsal fin features (D 15 and long dorsal fin base in H. sindonis vs. D 11 13 and short dorsal fin base in H. mohnikei ), but their key did not consider individual variations. Our H. sindonis specimens agree with both H. mohnikei and H. sindonis descriptions, but the paradoxical inconsistency between the original description and type series of H. mohnikei requires a further taxonomic review of this species, and, therefore, we compared our specimens with H. mohnikei holotype and not to the original description of the species ( Lourie et al. 1999; Eschmeyer et al. 2017).

Nakamura (1999a) described a single specimen of H. sindonis caught off Kumamoto, Japan, which is questionable, as there are no other records of H. sindonis from western Kyushu. This record may have been based on H. haema because spines were not mentioned in Nakamura s description. Kim et al. (2013) recorded a H. sindonis specimen from Korean waters (voucher: NIBR-P 5412; Fig. 5B). However, the morphology of this specimen indicates that it rather belongs to H. haema and we include it in the type series of H. haema . Thus, there are no reliable records of H. sindonis from Korea.