Stegastes nigricans (Lacepède, 1802)

Etymology and Naming

Stegastes nigricans was first described and named by Gerald Robert "Gerry" Allen and Alan R. Emery in 1985. The genus name Stegastes comes from the Greek word "stegastos", meaning covered. The species name nigricans is Greek for swarthy, black-skinned.

Taxonomy

Recent research classifies S. nigricans within the damselfish subfamily Pomacentrinae.

Size

This fish has an average total length of 9.0 cm, and can grow up to 14.0 cm long.

Fin Structure

It has 12 dorsal spines, 15 to 17 dorsal soft rays, 2 anal spines, and 12 to 14 anal soft rays.

Adult Base Coloration

Adult Stegastes nigricans are generally brown overall. The dorsal regions of the head and nape are darker, and the color fades to tan on the lower head and breast. Its scales have darker brown edges.

Head and Scale Markings

The lips are whitish, the suborbital is mostly blue, and the scales on the preopercle and opercle have blue centers.

Fin Coloration

The median and pelvic fins are brown, while the pectoral fins are dusky.

Species Identification Marker

There is sometimes a distinct dark brown or blackish spot at the base of the posteriormost dorsal fin rays; this clear spot distinguishes S. nigricans from S. lividus, which has a diffuse spot at this location.

Breeding Male Coloration

When courting or guarding eggs, males develop a broad white bar across the middle of their body, and a pale blue stripe running from the mouth to the upper section of the pectoral fin.

General Habitat

S. nigricans occurs naturally on and around coral reefs. Adult individuals live in colonies on reef flats and lagoon reefs in areas with staghorn coral.

Population Drivers

Their populations are limited by water temperature and diet, and have experienced negative impacts in recent years.

Habitat Threats

Global warming and fossil fuel use have driven changes to climate and ocean chemistry, which alter this species' habitat and cause large reductions in coral reef coverage.

Common Distribution Range

S. nigricans is most commonly found along the coast of East Africa and around Madagascar; in the British Indian Ocean Territory and along the southern coasts of India; across Southeast Asia, along the northern coast of Australia; and throughout Melanesia, Micronesia and Polynesia.

Less Frequent Occurrence Areas

It occurs less frequently in the Red Sea, the Persian Gulf, the Gulf of California, and along the western coast of Central America.