Pycnochromis leucurus
A small damselfish with a white tail and deep navy body.
The whitetail chromis, *Pycnochromis leucurus*, is a damselfish in the genus *Pycnochromis*. Its name comes from the Greek words *leukos* (white) and *oura* (tail). American ichthyologist Charles Henry Gilbert first described it in 1905, originally placing it in the genus *Chromis* as *Chromis leucura*. It was moved to *Pycnochromis* in 2021 after genetic work showed this lineage is more closely related to the genus *Dascyllus* than to *Chromis*.
Adults have a deep, navy blue body, yellow lower fins, and a pale, thread-like tail. A dark marking edged in yellow sits near each pectoral fin. Juveniles are blue-gray and reach up to 2.5 inches (64 mm) in length. The dorsal fin has 12 stiff spines and 14 flexible rays, while the anal fin has 2 spines and 13 to 15 rays.
This species lives in the Indo-Pacific, at depths between about 20 and 122 meters (66 to 400 feet). Early studies used specimens collected in the ʻAuʻau Channel between Maui and Lānaʻi, from depths of roughly 62 to 119 meters (203 to 390 feet). Whitetail chromis are often seen in small groups.
Quick Facts
- Genus
- Pycnochromis
- Species
- leucurus
Facts from the source article.
Lore & Background
The whitetail chromis was first described by American ichthyologist Charles Henry Gilbert in 1905, originally under the name Chromis leucura. It was reclassified to the genus Pycnochromis in 2021. Later genetic comparisons found that the Pycnochromis lineage is more closely related to the genus Dascyllus than to Chromis. The species name combines Greek leukos and oura, meaning 'white' and 'tail'.
This species are small fish with a deep, navy blue body, yellow lower fins, a pale thread-shaped tail, and a dark marking outlined in yellow near each pectoral fin. Young whitetail chromis are a blue-gray color and can grow up to 2.5 in (64 mm) in length. As they mature, its dorsal fin consists of 12 stiff spines and 14 flexible rays, while its anal fin contains 2 spines and between 13 and 15 rays.
Pycnochromis leucurus is found in the Indo-Pacific, between depths of approximately 20 and 122 m (66 and 400 ft). First studies of the species originated from specimens collected in the ʻAuʻau Channel between Maui and Lānaʻi at depths of approximately 62 to 119 m (203 to 390 ft). Whitetail chromis are often observed gathering in small numbers.
Reader's Guide
The whitetail chromis is notable for its reclassification history and genetic relationship to the genus Dascyllus rather than Chromis, as revealed by later genetic comparisons. First described by Charles Henry Gilbert in 1905 as Chromis leucura, it was reclassified to Pycnochromis leucurus in 2021. This taxonomic shift highlights ongoing refinements in damselfish phylogeny. The species' scientific name, derived from Greek for 'white' and 'tail', accurately describes its pale thread-shaped tail. Its physical description—deep navy blue body, yellow lower fins, and dark marking near each pectoral fin—distinguishes it from related species. The species was initially studied from specimens collected in the ʻAuʻau Channel between Maui and Lānaʻi at depths of 62 to 119 m, and it is found across the Indo-Pacific at depths from 20 to 122 m. Whitetail chromis are often observed gathering in small numbers, suggesting a social or aggregating behavior. Its maximum recorded length is 2.5 inches (64 mm), and fin ray counts provide diagnostic traits for identification.
Did You Know?
- It was reclassified from Chromis leucura to Pycnochromis leucurus in 2021.
- Genetic comparisons found the Pycnochromis lineage is more closely related to Dascyllus than to Chromis.
Frequently Asked Questions
Who is Pycnochromis leucurus?
The whitetail chromis is a small damselfish that belongs to the genus Pycnochromis. Charles Henry Gilbert first described it in 1905, and it was transferred from Chromis into its current genus in 2021.
What does Pycnochromis leucurus look like?
Adults show a deep navy-blue body with yellow lower fins and a slender, pale thread-like tail. A dark mark edged in yellow sits near each pectoral fin.
Why was Pycnochromis leucurus reclassified in 2021?
Genetic analyses demonstrated that this lineage is more closely allied to Dascyllus than to Chromis. Taxonomists therefore moved it into Pycnochromis to better reflect its true evolutionary placement.
What does the name Pycnochromis leucurus mean?
The specific epithet leucurus is built from the Greek words leukos (white) and oura (tail), a direct reference to the fish's distinctive pale caudal fin.
Who originally described Pycnochromis leucurus?
American ichthyologist Charles Henry Gilbert published the original description in 1905, naming it Chromis leucura. The species has since been reclassified under the genus Pycnochromis.
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