Hippocampus japapigu, Short, Graham, Smith, Richard, Motomura, Hiroyuki, Harasti, David & Hamilton, Healy, 2018

Short, Graham, Smith, Richard, Motomura, Hiroyuki, Harasti, David & Hamilton, Healy, 2018, Hippocampusjapapigu, a new species of pygmy seahorse from Japan, with a redescription of H. pontohi (Teleostei, Syngnathidae), ZooKeys 779, pp. 27-49 : 27

Hippocampus japapigu sp. n. Figures 1, 2, 3, 4, 5, 7, 8, 9, Video 1, Tables 1, 2

Holotype.

UW 157506, Fig. 1, 16.27 mm SL, off Imasaki, Okago, Hachijo-jima Island, Izu Islands, Japan, 33°08'48"N, 139°44'37"E, depth 10 m, 18 Aug. 2017, collected by Shoichi Kato using a hand net.

Paratypes.

UW 157507, Fig. 2A, 15.59 mm SL, off Imasaki, Okago, Hachijo-jima island, Izu Islands, Japan, 33°08'48"N, 139°44'37"E, depth 13 m, 18 Aug. 2017, S. Kato; KAUM - I. 111770, Fig. 2B, 14.54 mm SL, Yaene, Okago, Hachijo-jima Island, Izu Islands, Japan, 33°05'47"N, 139°46'10"E, depth 18 m, 12 Jan. 2018, S. Kato.

Other material.

Hachijo-jima Island, Izu Islands, Japan, July 2013, 10 to 20 m depth, two photographs of two individuals, R Smith (Figs 4, 5).

Comparative material.

Hippocampus pontohi AMS I.47833-001, Fig. 6. Data from H. bargibanti , H. denise , H. colemani , H. satomiae , and H. waleananus also from Kuiter (2003), Lourie and Kuiter (2008), and Gomon and Kuiter (2009).

Diagnosis. Hippocampus japapigu sp. n. differs from its congeners by the following combination of characters: tail rings 28; dorsal fin rays 14; pectoral fin rays nine; subdorsal rings four; bilaterally paired wing-like protrusions formed by a pair of large truncate spines projecting laterad on first superior trunk ridge; elevated dorsal ridge formed by unique triangular bony mounds dorsally on second, third, and fourth trunk rings with the posterior mound less pronounced; large and prominent spine projecting laterad on eighth lateral trunk ridge.

Description.

General body shape as in Figs 1-5. Morphometric and meristic characters listed in Table 1. Morphometric data ranges for the three type specimens: Head length 17.9-18.74% in SL, head depth 69.9-72.0% in HL; snout length 27.64-28.7% in HL, bulbous tip absent, snout depth 74.0-85.6% in SnL; post-orbital 55.3-49.9% in HL; distinct, angular coronet, coronet height 58.0-55.9% in HL, unbranched dermal appendage attached to anterior part of coronet; single gill-opening on midline behind coronet supported by elevated cleithral ring; dorsal fin 14 rays; pectoral-fin rays nine; anal fin rays four; trunk rings 12, trunk length 32.49-32.64% in SL, trunk depth just anterior to dorsal fin base 18.4-20.32% in SL; dorsal fin base strongly raised dorsally; subdorsal rings four, dorsal fin base starting immediately posterior to ninth trunk ring and ending immediately posterior to first tail ring; no external pouch visible; tail rings 28, tail length 48.73-49.42 % in SL. Body ornamentation: prominent spine dorsal of eye, small spine ventroposterior to eye; lateral head spine ventral of coronet; two moderately large spines on cleithral ring, upper spine at level of last pectoral fin ray, lower spine at ventral extent of ring; snout spine on midline between eyes; nape spine absent; subdorsal spines four, superior trunk ridge ending with three rounded spines protruding laterally, the posterior spine greatly enlarged on 12th trunk ring; superior trunk ridge with large truncate spines, connected by a solid bony ridge, projecting dorsolaterad on first trunk ring, unique triangular bony mounds arched dorsally on second, third, and fourth trunk rings with the posterior mound less pronounced, trunk appearing denticulate in lateral view, very large bilaterally paired spines on fifth trunk ring, and small spines on sixth trunk ring; lateral trunk ridge with small spine on fifth trunk ring and very large spine on eighth trunk ring; inferior trunk ridge with spines of moderate size beginning on fifth trunk ring and ending on 12th trunk ring; superior tail ridge spines well developed anteriorly, becoming smaller posteriorly, with enlarged spines on fifth, ninth, 12th, and 16th tail rings; inferior tail ridge spines absent; caudal fin absent.

Color in life.

Hippocampus japapigu (Figs 4, 5, and 7) exhibits cryptic coloration: head, trunk and tail, brown, with overlay of reticulate (net-like) irregular quadrilateral and pentagonal skin formations, brown or white, white outline, entire surface of head and body peppered with tiny black dots; elevated dorsal ridge on second to fourth superior trunk rings, engorged red, reticulate color pattern diffuse or absent; dorsal fin base, red, reticulate pattern absent; tail rings with one row of rounded quadrilaterals present, one quadrilateral per ring, brown with white outline; fifth superior ridge spine red; fifth and eighth lateral trunk ridge spines, white; eighth inferior trunk ridge spine, red; fifth, ninth, 12th superior tail ridge spines, red, every fourth ring thereafter with two dorsolateral color spots, red; dermal appendages on coronet anteriorly.

Color in alcohol.

Light brown in holotype, pale brown in paratype, with black dots scattered over head, trunk, and anterior to tail.