Syngnathus chihiroe Matsunuma, 2017, sp. nov.

Syngnathus chihiroe sp. nov.

English name: Deepwater Pipefish Standard Japanese name: Chihiro-yōji

Holotype. NSMT-P 106296, female, 92.0 mm SL, Hirase Shoal, southwest of Yakushima Island, Kagoshima Prefecture, Japan (East China Sea), 30°02′N, 130°03′E, 160–162 m depth, R/ V Tansei -maru, Cruise KT-93-09, Station YT-16 (2), 1 m ORI. biol. dredge, 18 June 1993.

Diagnosis. Dorsal-fin rays 38; pectoral-fin rays 17; trunk rings 18; tail rings 40; total rings 58; subdorsal rings 3.25 + 10.0 = 13.25; HL 8.7 in SL (11.5% SL); snout length 2.3 in HL (43.1% HL); snout depth 8.5 in HL (11.7% HL); snout depth 3.7 in snout length (27.2% snout length); anal ring depth 3.2 in HL (31.4% HL); body ridges entirely smooth without serrae or spines.

Description. Meristics and morphometrics shown in Tables 1 –3. Body elongate, tail clearly longer than trunk (Fig. 1); rings bearing dorsal fin not elevated dorsally; 1st trunk ring bearing pectoral fin, clearly longer than 2nd ring. Brood pouch absent. Head small; snout short, moderately deep, not depressed laterally or ventrally (Figs. 2 A– B). Dermal flaps absent on head and body. Margins of all ring ridges smooth, without serrae or spines. Superior trunk and tail ridges discontinuous, trunk ridge ending near level of last dorsal-fin ray base, tail ridge (= lateral tail ridge) running downward, straight below greater portion of dorsal-fin base, ending below 10th dorsal-fin ray base (Fig. 2 C–D); inferior trunk ridge confluent with inferior tail ridge; lateral trunk ridge running straight, posteriormost portion canted slightly downward, ending below 12th dorsal-fin ray base; lateral trunk and tail ridges discontinuous.

Holotype

NSMT-P 106296

Dorsal-fin rays 38

Anal-fin rays 3

Pectoral-fin rays 17 on both sides

Caudal-fin rays 10

Trunk rings 18

Tail rings 40

Subdorsal rings 3.25 + 10.0 = 13.25

Standard length (mm) 92.0

% SL % HL in SL in HL Trunk length 29.5 255.8 3.4 0.4 Tail length 59.5 516.2 1.7 0.2 Head length 11.5 — 8.7 — Head width 3.4 29.6 29.4 3.4 Snout length 5.0 43.1 20.2 2.3 Snout depth 1.3 11.7 74.2 8.5 Orbit diameter 2.2 19.2 45.3 5.2 Interorbital width 0.8 7.3 119.4 13.8 Trunk depth 3.7 32.3 26.9 3.1 Trunk width 3.7 31.7 27.4 3.2 Anal ring depth 3.6 31.4 27.7 3.2 Dorsal-fin base length 20.3 175.8 4.9 0.6 Dorsal-fin height 3.1 27.0 32.2 3.7 Anal-fin length 0.7 5.8 150.7 17.4 Pectoral-fin length 2.7 23.3 37.2 4.3 Pectora-fin base length 1.9 16.1 53.8 6.2 Caudal-fin length 3.0 26.1 33.3 3.8 Median dorsal snout ridge very low, continuous, extending posteriorly just in front of anterior margin of orbit, with 2 slight depressions on anterior half and low expansion just in front of orbit but without distinct serrations; lateral aspects of snout smooth, without distinct ridges or spines. Interorbital portion narrow, depressed; dorsal rim of orbit slightly flared laterally, slightly elevated dorsally; supraorbital, frontal and median head ridges low, vestigial. Opercular ridges undeveloped, median ridge incomplete, short, angled dorsally, its length about half orbit diameter; distinct supraopercular ridge absent. Pectoral-fin base slightly protruding laterally, with single short longitudinal ridge on dorsal portion of base.

Dorsal fin height about 80% of trunk depth, its base very long, origin situated on trunk; anal fin present, very small, situated just behind anus; pectoral fin moderately long, its posterior tip reaching posterior margin of 2nd trunk ring when laid along body; caudal fin small, with rounded contour, middle rays not elongate.

Color of preserved specimen. Head and body uniformly creamy-white without markings; pectoral-fin base narrowly margined with brown; all fins semi-translucent.

Distribution. The species is currently known only from the type locality, southwest of Yakushima Island, Kagoshima Prefecture, Japan (East China Sea), in a depth of 160–162 m (Fig. 3).

Etymology. The specific name, chihiroe, is derived from Japanese “chihiro”, meaning great depth, alluding to the depth of capture of the holotype and only known specimen (160–162 m), one of the deepest recorded for any member of the genus (Table 4).

Remarks. The new species, with trunk rings 18, total rings 58; dorsal-fin rays 38, total subdorsal rings 13.25; pectoral-fin rays 17; anal-fin rays 3; caudal-fin rays 10; superior and tail ridges discontinuous, lateral trunk ridge ending near anal ring, inferior trunk and tail ridges continuous (Fig. 2 C–D); median dorsal snout ridge low, entire (Fig. 2 A–B); snout without dorsolateral spines or denticulations, a median lateral ridge or spines; median dorsal head ridges not strongly elevated; supraopercular ridge absent; longitudinal opercular ridge incomplete; pectoralfin base not strongly protruding laterally, with single longitudinal ridge; dorsal-fin origin situated at trunk, fin base not elevated; principal body ridges weakly elevated, entirely smooth without spines or prominent denticulations; dermal flaps absent, is assigned to the genus Syngnathus, as these characters conform closely to the diagnostic features of the genus given by Fritzsche (1980) and Dawson (1985). Although brood pouch morphology in males is a diagnostic feature in syngnathids, the holotype of S. chihiroe is female and lacks the brood pouch.

Following Fritzsche (1980), Dawson (1982, 1985, 1986), Paulus (1992), Kuiter (2009), Naseka & Bogutskaya (2009), Eschmeyer et al. (2016), and Kullander (2016), 34 nominal species of Syngnathus are regarded here as valid. Comparisons of selected meristic characters of S. chihiroe and congeners are shown in Table 2. The former can be primarily distinguished from the other species by its generally greater number of pectoral-fin rays, in addition to variable differences in numbers of dorsal-fin rays, tail rings, total rings, subdorsal trunk rings, subdorsal tail rings and total subdorsal rings.

Selected morphometrics of S. chihiroe and other species of Syngnathus (Table 3) show that the former is characterized by a relatively short deep snout compared with some congeners, including S. dawsoni, S. floridae, S. folletti, S. louisianae, S. schlegeli, S. macrophthalmus and S. safina.

Syngnathus schmidti (Black Sea and Sea of Azov), shares similar counts of fin rays and body rings with S. chihiroe, but possesses a longer snout, its length more than half of head length (Dawson 1982), whereas the latter possesses a shorter snout (length 0.43 times head length). Moreover, S. schmidti clearly differs from S. chihiroe in having the distal margins of the body rings typically with spine-like points in sub-adults and adults (Dawson 1982), unlike the entirely smooth body rings of S. chihiroe . Syngnathus argentatus (Black Sea) and S. typhle (northeastern Atlantic Ocean) possesses similar meristic counts with S. chihiroe, but have the snout strongly compressed laterally with a highly elevated median dorsal ridge (Dawson 1982; Amor et al. 2007; Kuiter 2009), features not found in S. chihiroe.

ABLE 2. Comparisons of selecteđ meristics in Syngnathus.

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Dorsal-fin origin situateđ between anterior margin of last trunk ring anđ posterior margin of 2nđ tail ring. Dorsal+fin origin situateđ between anterior margin of last trunk ring anđ miđđle of 1st tail ring.

, A et al., D, E, F, K, anđ P inđicate Artüz, Amor et al., Dawson, Eichwalđ, Fritzsche, Kuiter anđ Paulus, respectively.

TABLE ³. Comparisons of selecteđ morphometrics in Syngnathus.

et al., D, anđ P inđicate Amor et al., Dawson anđ Paulus, respectively.

Syngnathus chihiroe can be readily distinguished from S. schlegeli (Fig. 4), the only other recognized northwestern Pacific Ocean congener (Dawson 1985). [Although Ni & Kwok (1999) noted many literature records of the two Atlantic species, S. acus and S. pelagicus, from Hong Kong, they are most likely misidentifications of S. schlegeli.]. Syngnathus chihiroe differs from the latter in having 17 pectoral-fin rays (vs. 11–15 in the latter), 3.25 subdorsal trunk rings (vs. 1.75–0.0), and a short deep snout, snout length 2.3 in HL and snout depth 3.7 in snout length (vs. 1.6–2.0 and 5.6–11.3, respectively) (data for S. schlegeli taken from Dawson 1985). Comparisons of S. chihiroe with S. schlegeli specimens examined in the present study are shown in Fig. 5, indicating consistent differences between the two species, viz., snout length 43.1% HL in the former (vs. 48.8–55.7% HL in the latter); snout depth 11.7% HL (vs. 6.3–9.6% HL); anal ring depth 31.4% HL (vs. 11.5–15.6% HL); and snout depth 27.2% snout length (vs. 6.3–9.6% snout length). Contrary to the deep water habitat of the holotype of S. chihiroe, adults of S. schlegeli inhabit seagrasses or algal reefs in coastal inlet and estuarine waters to about 15 m depth (Kuiter 2009; Senou 2013).