Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Jul 30:13:e19789.
doi: 10.7717/peerj.19789. eCollection 2025.

New and known free-living nematode species (Nematoda: Chromadorea) from offshore tsunami monitoring buoys in the Southwest Pacific Ocean

Daniel Leduc  1
Affiliations

New and known free-living nematode species (Nematoda: Chromadorea) from offshore tsunami monitoring buoys in the Southwest Pacific Ocean

Daniel Leduc. PeerJ. .

Abstract

Deep-ocean Assessment and Reporting of Tsunami (DART) buoys are deployed across the Southwest Pacific and provide substrates for biofouling communities. Two new free-living nematode species, Atrochromadora tereroa sp. nov. and Euchromadora rebeccae sp. nov. (family Chromadoridae), and one known species, Halomonhystera refringens (Bresslau & Schuurmans Stekhoven, 1933) comb. nov. (family Monhysteridae), are described from buoys deployed off Raoul Island in the Kermadec/Rangitāhua region and off New Zealand's East Cape. Thalassomonhystera refringens (Bresslau & Schuurmans Stekhoven, 1933) Jacobs, 1987 and T. anoxybiotica (Jensen, 1986) Jacobs, 1987 are transferred to Halomonhystera based on the presence of precloacal and caudal papillae in males. In addition, Halomohystera zhangi Li, Huang & Huang, 2024 is synonymised with Halomonhystera refringens. Updated keys to Atrochromadora, Euchromadora and Halomonhystera species are provided. The presence of nematodes on buoys located more than 100 km from the nearest landmass and in deep waters (>3,500 m water depth) shows that some nematode species are capable long-distance dispersal to colonise new substrates. Such dispersal by Atrochromadora, Euchromadora and Halomonhystera species likely occurs via drifting macroalgal fragments.

Keywords: Chromadorida; Epiphytic; Monhysterida; Nematoda; New species.

PubMed Disclaimer

Conflict of interest statement

The authors declare there are no competing interests.

Figures

Figure 1
Figure 1. Map of sampling locations.
Map showing location of the Deep ocean Assessment and Reporting of Tsunami (DART) buoys C and F sampled in this study, in relation to New Zealand’s North Island and Raoul Island.
Figure 2
Figure 2. Deep ocean Assessment and Reporting of Tsunami (DART) buoys.
(A) Buoy F (Kermadec region) immediately prior to retrieval; (B) retrieval of buoy F; (C) buoy F immediately after retrieval, showing mix cover of filamentous algae and goose barnacles; (D) close up of buoy C (East Cape region) showing mixed cover of filamentous algae and goose barnacles.
Figure 3
Figure 3. Atrochromadora tereroa sp. nov. drawings.
(A) Pharyngeal body region of holotype male (NIWA 181659); (B) anterior body region of female paratype (NIWA 181660); (C) anterior body region of male paratype (NIWA 181660); (D) pharyngeal body region of female paratype (NIWA 181660); (E) copulatory apparatus of male holotype (NIWA 181659); (F) posterior body region of male paratype (NIWA 181660). Scale bar: A & D = 25 microns, B & C = 20 microns, E = 23 microns, F = 36 microns.
Figure 4
Figure 4. Atrochromadora tereroa sp. nov. drawings.
(A) Posterior body region of female paratype (NIWA 181660); (B) entire male paratype (NIWA 181660); (C) reproductive system of female paratype (NIWA 181660); (D) posterior body region of male paratype (NIWA 181660). Scale bar: A = 50 microns, B = 100 microns, C = 60 microns, D = 40 microns.
Figure 5
Figure 5. Atrochromadora tereroa sp. nov. light micrographs.
(A) Entire male paratype (NIWA 181660); (B) surface view of female paratype anterior body region (NIWA 181660); (C) optical cross-section of female paratype anterior body region (NIWA 181660); (D) pharyngeal bulb of male holotype (NIWA 181659); (E & D) mature egg and vulva of female paratype (NIWA 181660). Scale bar: A = 100 microns, B & C = 11 microns, D = 12 microns, E & F = 14 microns.
Figure 6
Figure 6. Euchromaodra rebeccae sp. nov. drawings.
(A) Pharyngeal body region of male holotype (NIWA 182672); (B) anterior body region of male holotype (NIWA 182672); (C) anterior body region of female paratype (NIWA 182673); detail of lateral body cuticle of female paratype (NIWA 182673): (D) slightly posterior to cephalic region; (E) & (F) posterior end of pharynx (different focus); (G) & (H) mid-body (different focus); (I) anal region; (J) tip of tail. Scale bar: A = 100 microns, B & C = 50 microns, D–J = 32 microns.
Figure 7
Figure 7. Euchromaodra rebeccae sp. nov. drawings.
(A) Entire male holotype (NIWA 182672); (B) posterior body region of female paratype (NIWA 182673); (C) copulatory apparatus of male paratype (NIWA 182673); (D) posterior body region of male holotype (NIWA 182672); (E) reproductive system of female paratype (NIWA 182673). Scale bar: A = 150 microns, B = 86 microns, C = 50 microns, D = 90 microns, E = 165 microns.
Figure 8
Figure 8. Euchromaodra rebeccae sp. nov. light micrographs.
(A, B, C & D) Optical cross sections and surface view of anterior body region of male paratype (NIWA 182673); (E) posterior body region of female paratype (NIWA 182673). Scale bar: A–D = 20 microns; E = 44 microns.
Figure 9
Figure 9. Euchromadora rebeccae sp. nov. light micrographs.
Spicular apparatus of male holotype (NIWA 182672) showing spicules, dorsal piece of gubernaculum and distal end of telamon (A) and proximal part of telamon (B). Scale bar = 20 microns.
Figure 10
Figure 10. Halomonhystera refringens (Bresslau & Schuurmans Stekhoven, 1933) comb. nov. drawings.
(A) Pharyngeal body region of male; (B) female cephalic region; (C) female posterior body region; (D) male posterior body region. Figure 1. Scale bar: A = 35 microns, B = 20 microns, C = 40 microns, D = 30 microns.
Figure 11
Figure 11. Halomonhystera refringens (Bresslau & Schuurmans Stekhoven, 1933) comb. nov. line drawings.
(A) Entire male; (B) entire female. Scale bar = 100 microns.
Figure 12
Figure 12. Halomonhystera refringens (Bresslau & Schuurmans Stekhoven, 1933) comb. nov. light micrographs.
(A) Entire male; (B) male anterior body region; (C) male intestine with several diatoms; (D) female anal body region. Scale bar: A = 100 microns, B = 13 microns, C & D = 18 microns.
See this image and copyright information in PMC

Similar articles

See all similar articles

References

    1. Allgén CA. Weitere Beiträge zur Kenntnis der marinen Nematodenfauna der Campbellinsel. Nyt Magazin for Naturvidenskaberne. 1932;70:97–198.
    1. Apolonio Silva de Oliveira D, Decraemer D, Moens T, Dos Santos GAP, Derycke S. Low genetic but high morphological variation over more than 1,000 km coastline refutes omnipresence of cryptic diversity in marine nematodes. BMC Evolutionary Biology. 2017;17:71. doi: 10.1186/s12862-017-0908-0. - DOI - PMC - PubMed
    1. Bik HM, Thomas WK, Lunt DH, Lambshead PJD. Low endemism, continued deep-shallow interchanges, and evidence for cosmopolitan distributions in free-living marine nematodes (order Enoplida) BMC Evolutionary Biology. 2010;10:389. doi: 10.1186/1471-2148-10-389. - DOI - PMC - PubMed
    1. Boeckner MJ, Sharma J, Proctor HC. Revisiting the meiofauna paradox: dispersal and colonization of nematodes and other meiofaunal organisms in low- and high-energy environments. Hydrobiologia. 2009;62:91–106. doi: 10.1007/s10750-008-9669-5. - DOI
    1. Bresslau E, Schuurmans Stekhoven Jr JH. Marine freilebende Nematoda aus der Nordsee. Musée d’Histoire Naturelle de Belgique; Bruxelles: 1940. p. 74.

LinkOut - more resources