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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: an euryhaline polychaete

Synonyms and Other Names: Laonome calida

Identification: Laonome xeprovala is a small, eyeless sabellid polychaete with a pale-yellow body inside a translucent mucous tube (Pant et al. 2025). This species has 6–8 brown bands along its branchial crown, a soft-feather like structure composed of radioles that is attached to the head of the polychaete. The branchial crown of L. xeprovala contains 6–8 pairs of radioles unlike some other members of this genus which have 10 or more pairs (Bick et al. 2018). The body of this species is cylindrical and narrows towards the posterior end (Pant et al. 2025).

This species is very difficult to distinguish from other members of the Laonome genus without genetic confirmation.

Size: Recorded body length up to 20 mm excluding branchial crown (Pant et al. 2015).

Native Range: The native range of this species is unknown. It was first observed in the Netherlands in 2009 and has since been identified in various fresh to brackish waters in northwestern Europe (Bick et al. 2018).

Alaska	Hawaii	Puerto Rico & Virgin Islands	Guam Saipan

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Ecology: Laonome xeprovala inhabits the benthos of shallow (0.5–12 m depth) waters with low salinity (0.5–7 psu). It has been recorded on various sediment types including sandy silt, sand, silt-clay, soft clay, and hard bottoms (Bick et al. 2018). This species can survive in low water temperatures of below two degrees Celsius and extended periods of ice cover (Kotta et al. 2015).

While information on reproduction is limited, this species has been observed to carry small eggs in their abdomen of 135 µm in diameter that hatch into planktonic larvae (Kotta et al. 2015; Bick et al. 2018). In European waters, individuals were found to be carrying eggs in August and September. Spawning appears to begin earlier in fresher waters evidenced by juvenile L. xeprovala living in the tubes of adults in early Fall (Bick et al. 2018).

Means of Introduction: The exact means of introduction of this species is unknown. The most likely pathways include shipping ballast water or hull fouling (Pant et al. 2025).

Status: Laonome xeprovala is established within the La Grange reach of the Illinois River (Pant et al. 2025).

Impact of Introduction: The impacts of this species are currently unknown. 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.

Remarks: There are at least two other unidentified Laonome species in the western United States. Both identification and native status remains undetermined (Pant et al. 2025).

References: (click for full references)

Bick, A., R. Bastrop, J. Kotta, K. Meißner, M. Meyer, and V. Syomin. 2018. Description of a new species of Sabellidae (Polychaeta, Annelida) from fresh and brackish waters in Europe, with some remarks on the branchial crown of Laonome. Zootaxa 4483(2): 349–364. https://doi.org/10.11646/zootaxa.4483.2.7.
Kotta, J., I. Kotta, A. Bick, R. Bastrop, and R. Väinölä. 2015. Modelling habitat range and seasonality of a new, non-indigenous polychaete Laonome sp. (Sabellida, Sabellidae) in Pärnu Bay, the north-eastern Baltic Sea. Aquatic Invasions 10(3): 275–285. https://doi.org/10.3391/ai.2015.10.3.03.
Pant, M., J.C. Dreyer, and J. Lamer. 2025. First record of the euryhaline polychaete Laonome xeprovala (Sabellidae) from the U.S. Midwest. Biological Invasions 27(7): article 169. https://doi.org/10.1007/s10530-025-03629-x.

Other Resources:
Read, G.; Fauchald, K. (Ed.) (2025). World Polychaeta Database. Laonome xeprovala Bick & Bastrop, in Bick et al. 2018. Accessed through: World Register of Marine Species at: https://www.marinespecies.org/aphia.php?p=taxdetails&id=1299379 on 2025-07-16.

Author: Stratton, L.D.

Peer Review Date: 7/28/2025

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.