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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

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Common name: whitetail damselfish

Synonyms and Other Names: whitetail major

Taxonomy: available through www.itis.gov

Identification: The whitetail damselfish has an oval compressed body with a bluntly forked caudal fin and moderately large rough scales (Robertson and Allen 2015). Adults are dark brown with darker scale edges, a blue iris, and their pectoral fins have a yellow margin (Robertson and Allen 2015). They often have a whiteish band on the base of the tail fin (Robertson and Allen 2015). Juveniles are overall a purplish-brown grading to yellow from the forehead along the anterior portion of the back up to the end of the spinous dorsal fin (Allen and Woods 1980). They have a dark spot at the rear base of the soft dorsal fin with a white bar across the base of the tail fin (Robertson and Allen 2015).

Size: Up to 11.5 cm standard length (Allen 1991), total length to 17 cm (Allen and Robertson 1994)

Native Range: Whitetail damselfish are found in the tropical Eastern Pacific Ocean. They are common in the Revillagigedo and Guadalupe Islands and found from the southern Gulf of California to Mazatlán, Mexico (Allen 1991).

Interactive maps: Point Distribution Maps

Ecology: This species inhabits shallow rocky reefs (Allen 1991). They are omnivores and feed on benthic crustaceans, worms, and algae (Robertson and Allen 2015).

Reproduction: Breder and Coates (1933) observed a breeding pair in captivity carrying several mouthfuls of sand to potential egg laying sites. The fish blew the sand out and vigorously fanned the site effectively sand blasting the surface until cleaned. The female then laid concentric circles of eggs that were fertilized by the male and tended by both parents. They estimate 400-500 eggs were laid.

Means of Introduction: Probably a waif from the native range.

Status: Unknown

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

An adult as well as juveniles were observed defending reef territory against native Garibaldi damselfish, Hypsypops rubicundus (Love et al. 2016).

Remarks: The IUCN has listed the whitetail damselfish as a vulnerable species in its native range (Allen et al. 2010).

References: (click for full references)

Allen, G.R. 1991. Damselfishes of the World. Mergus Publishers, Germany.

Allen, G. R. and Robertson, D.R. 1994. Fishes of the tropical eastern Pacific. University of Hawaii Press, Honolulu.

Allen, G., Robertson, R., Zapata, F. 2010. Stegastes leucorus. The IUCN Red List of Threatened Species 2010: e.T183963A8207287. http://dx.doi.org/10.2305/IUCN.UK.2010-3.RLTS.T183963A8207287.en. Downloaded on 19 August 2019.

Breder, C.M. and Coates, C.W. 1933. Reproduction and eggs of Pomacentrus leucoris Gilbert. American Museum Novitates 612:1-6.

Hernández-Velasco, A., Fernández-Rivera-Melo, F.J., Melo-Merino, S.M., and Villaseñor-Derbez, J.C. 2016. Occurrence of Holacanthus clarionensis (Pomacanthidae), Stegastes leucorus, and Stegastes acapulcoensis (Pomacentridae) at Magdalena Bay, B.C.S., Mexico. Marine Biodiversity Records 9:49.

Love, M.S., Bushing, W.W., and Power, W. 2016. The whitetail damselfish (Family Pomacentridae), Stegastes leucorus (Gilbert, 1892), new to California marine waters with a key to the California species of Pomacentridae. Bulletin of the Southern California Academy of Sciences 115(2): 136-139.

Robertson, D.R. and Allen, G.R. 2015. Shorefishes of the tropical Eastern Pacific: online information system. Version 2.0 Smithsonian Tropical Research Institute, Balboa, Panama. https://biogeodb.stri.si.edu/sftep/en/pages.

Other Resources:

Author: Brown, M.E., and Schofield, P.J.

Peer Review Date: 9/30/2019

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.