Three new pygmy seahorse species from Indonesia (Teleostei: Syngnathidae: Hippocampus)

Three new species of pygmy seahorse are described from Indonesia: Hippocampus pontohi and H. severnsi from Bunaken Island, off Sulawesi, and H. satomiae from Derawan Island, off Kalimantan. They are considered to be closely related to each other and to Hippocampus colemani. All three species are morphologically distinguished from the larger species of seahorses by the following combination of characters: 12 trunk rings, low number of tail rings (26-29), the placement of brooded young within the trunk region of males, and extremely small size (<15 mm HT, <17 mm SL). They can be separated from the previously described species of pygmy seahorses (H. bargibanti, H. denise, H. colemani and H. minotaur) based on meristics, proportions, colour and body ornamentation. All three new species have a single gill opening as does H. colemani. Hippocampus pontohi and H. severnsi also share distinctive fleshy appendages with H. colemani but can be separated from the latter based on their body shape, raised angular coronet, larger orbit diameter, narrower trunk, fewer tail rings, smaller overall size and in the case of H. severnsi also colour. Diagnostic features of H. satomiae include 9 pectoral fin rays, 13 dorsal fin rays, spinous exterior, and distinct raised coronet with laterally expanded anterior and posterior flanges.