Hippocampus japapigu, a new species of pygmy seahorse from Japan, with a redescription of H. pontohi (Teleostei, Syngnathidae)

By

Short, Graham
Smith, Richard
Motomura, Hiroyuki
Harasti, David
Hamilton, Healy

Type

Article

Date of Publication

2018

Original Publication

ZooKeys

Volume

779

Pages

27-49

Subjects

Acanthomorpha , computed tomography , new species , Reef fish , systematics , taxonomy

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/zookeys.779.24799

 

Abstract

The pygmy seahorseHippocampusjapapigusp. n.is described based on three specimens, 13.9–16.3 mm SL, collected from a mixed soft coral and algae reef at 11 m depth at Hachijo-jima Island, Izu Islands, Japan. The new taxon shares morphological synapomorphies with the previously described central Indo-Pacific pygmy seahorses,H.colemani,H.pontohi, H.satomiae, andH.waleananus, including extremely small size, 12 trunk rings, strongly raised continuous cleithral ring, snout spine, large spine on the eighth lateral and fifth and 12 superior trunk ridges, respectively, and unusual wing-like-protrusions immediately posterior to the head.Hippocampusjapapigusp. n.can be distinguished from all congeners by the following combination of features in the anterodorsal area of the trunk: bilaterally paired wing-like protrusions formed by a single pair of large, truncate spines projecting dorsolaterad on the first superior trunk ridge, followed by a unique elevated dorsal ridge formed by triangular bony mounds dorsally on the second to fourth superior trunk ridges. In contrast,H.pontohipossesses a pair of large truncate spines projecting strongly laterad on both the first and second superior trunk ridges followed by flat surfaces dorsally on the third and fourth superior trunk rings. The new species can be further differentiated by genetic divergence fromH.pontohi(an uncorrected p-distance of 10.1% in the mitochondrial COI gene) and a striking reticulated white and brown lattice pattern on the head, trunk, and tail.Hippocampusjapapigusp. n.represents the fifth species of pygmy seahorse recorded in Japan.