Antigonia emanuela – Emanuela’s boarfish

Antigonia emanuela – Emanuela’s boarfish ©FAO/M. Lipperi

Emanuela’s boarfish is a species endemic to Myanmar, found at moderate depths where light begins to fade. It features a deeply rhomboid body covered with spiny scales and bright yellow to reddish fins. Adapted for slow, energy-efficient swimming, not much is known about its behaviour, reproduction or ecology, making it a fascinating subject for further deep-sea research.

The discovery

During two research cruises in Myanmar conducted by the EAF-Nansen Programme aboard the research vessel Dr. Fridtjof Nansen in 2015 and 2018, specimens of several Antigonia species were collected. Most of these specimens were identified as species previously reported and described from the western Indian Ocean, confirming known distribution patterns. However, two specimens stood out because they could not be conclusively matched to any known species within the genus. These specimens were photographed, preserved, and sent to the South African Institute for Aquatic Biodiversity in Grahamstown, where three taxonomists conducted further examinations, revealing morphological and genetic differences with all known Antigonia species.

The recognized number of Antigonia species has increased in recent years, and some widely distributed species may represent complexes of multiple, distinct species. Further research, particularly in the eastern Indian Ocean and western Pacific, is expected to uncover new species and provide greater clarity on their distributions.

Features and characteristics

Emanuela’s boarfish is distinguished within its genus by a unique combination of traits, including a deeply rhomboid body, 9 dorsal-fin spines, 13 pectoral-fin rays, and a strongly bent premaxilla. Its scales feature a prominent apical crest densely armed with multiple rows of spines covering nearly the entire lateral surface. In life, the body exhibits a pink hue with silvery highlights, a yellow iris, a reddish-orange stripe across the breast, and fins that range from bright yellow to reddish, with red pennants adorning the tips of the spiny dorsal fin.

This species belongs to the family Antigoniidae, a small group comprising 22 species within the genus Antigonia. Members of this genus are characterized by their deep, slender bodies and vivid red coloration. They inhabit tropical and subtropical waters of the Indian, Pacific, and Atlantic Oceans, typically found at depths between 50 m and 600 m.

The body shape of Antigonia species is adapted for slow, energy-efficient swimming, ideal for the low-energy environment of the deep sea. Their strongly bent premaxilla enables a specialized feeding mechanism that helps them capture small prey such as plankton and tiny invertebrates. Due to their deep-water habitat, many aspects of their behaviour, reproduction and ecology remain largely unknown, but we know that adults are found close to the bottom while juveniles occur in mid-water.

Left/Top: Microscope image of a fish scale showing the detailed apical crest (white arrow) and spine-like ctenii structures (black arrow) that provide protection and texture. (Scale bar 0.5 mm). Source: Prokofiev et al. (2020).

Right/Bottom: Photo of the holotype of Antigonia emanuela immediately after capture. Source: Prokofiev et al. (2020).

Geographical distribution

This species is known only from the type locality, off Myanmar’s Ayeyarwady Delta in the Andaman Sea. It was collected at a depth range of 99–129 m.

Resources

• Prokofiev, A.M., Psomadakis, P.N. & Gon, O. (2020). A new deep-bodied species of Antigonia (Teleostei, Antigoniidae) from the Andaman Sea (northeastern Indian Ocean). Zootaxa, 4763 (2), 203–216. https://doi.org/10.11646/zootaxa.4763.2.4.