Progoniada regularis Hartman, 1965

Meissner, Karin, Schwentner, Martin, Göưing, Miriam & Fiege, Thomas Knebelsberger and Dieter, 2023, Polychaetes distributed across oceans-examples of widely recorded species from abyssal depths of the Atlantic and Pacific Oceans, Zoological Journal of the Linnean Society 199, pp. 906-944 : 924-925

Progoniada regularis Hartman, 1965

( Figs 10C–F )

Progoniada regularis Hartman, 1965: 100 , pl. 16a–f. – Rizzo and Amaral 2004a: 48–52, figs 1A–E, 2A–I, 3A–J.– Böggemann, 2005: 155–160, figs 86–88. – Böggemann 2009: 312, figs 43, 45–47. – Fiege et al. 2010: appendix, tables 3 and 5 (name only). – Moreira and Parapar 2015: 85–87, fig. 36A–J. – Böggemann and Dietz 2016: 1509–1510. – Böggemann 2016: 239–240, figs 10, 11. – Böggemann & Sobczyk in Gunton et al. 2021: 48 (name only).

Material examined: Central Atlantic Ocean, Mid-Atlantic Ridge, West, SO 237 (VEMA-Transit), station 9-8, 5004 m (ZMH-P 26697, SEM 1341). SW Atlantic Ocean, Brazil Basin S, M 79-1 (DIVA 3), station 561-1, 4484 m (SMF 23790). SE Pacific Ocean, Peru Basin (DISCOL area), SO 242-1 (JPIO-DISCOL 1), station 37-1, 4161 m (SMF 30498, SMF 30499, SMF 30500, SMF 30501, SMF 30502); station 85-1, 4147 m (SMF 30497). – for details and additional specimens see the Supporting Information, Table S2 .

Measurements largest specimens studied: Central Atlantic (ZMH-P 26697):length 4.6mm,width 0.2mm (excl.parapodia),35chaetigers for largest specimen studied; SE Pacific, Peru Basin (SMF 30502): length 7.5 mm, width 0.35 mm (excl. parapodia), 30 chaetigers.

Description: Prostomium with eight annulations ( Fig. 10C ). Tip with biarticulate appendages. Eyes absent. Proboscis with paired lateral rows of chevrons (five in specimen collected from the central Atlantic, ZMH-P 26697) ( Fig. 10C, E ) and doưed with several rows of small cordiform papillae ( Fig. 10E, F ). Parapodia all uniramous ( Fig. 10D ). Prechaetal lobe long, digitiform; postchaetal lobe short, rounded. First segment apodous and with lateral cirri only. Dorsal and ventral cirri digitiform of similar length, slightly shorter than prechaetal lobe ( Fig. 10D ). Chaetae compound spinigers and falcigers.

Remarks: Specimens studied from the central Atlantic and Peru Basin agree morphologically with the descriptions published by Rizzo and Amaral (2004a) and Böggemann 2005. The number of chevrons found for specimen ZMH-P 26697 collected from the central Atlantic is lower than given with 14–22 by Rizzo and Amaral (2004a) but falls into the range from 4 to30 as given by Böggemann 2005. Some specimens from central Atlantic (ZMH-P 26697) and from Peru Basin (SMF 30497) with a median, brownish pigment dot ventrally on segments (from ca.chaetiger 13 onwards in ZMH-P 26697), as described and figured by Rizzo and Amaral (2004a: fig. 3D). Böggemann (2022) considers P. oahuensis Barret & Bailey-Brock,2005 a synonym of P.regularis with the difference in length of falcigerous blades as the main distinguishing character, i.e. shorter in P. oahuensis and longer in P. regularis , to be related to specimen size. This leaves P.regularis the only species in the genus currently valid as P. simplex Hartman 1971 was already synonymized by Böggemann 2005. According to Böggemann (2009), P. regularis is a complex of cryptic or sibling species based on his molecular results, while Böggemann and Dietz (2016) consider P. regularis a cosmopolitan species occuring at depths from 10 to 5655 m. Specimens of P. regularis considered here collected from the Pacific (CCZ and Peru Basin), as well as from the central Atlantic (VEMA Fracture Zone), could not be separated based on our molecular data, thus extending the already wide distribution of P. regularis to abyssal depths in the central Atlantic and the central and SE Pacific ( Fig. 3 ).

Distribution: Central Pacific (CCZ: 4280 m, this study), SE Pacific ( Peru Basin: 4147–4161 m, this study); Central Atlantic (VEMA Fracture Zone: 5004 m, this study), South Atlantic, Guinea (3945–5470 m), Angola (5424–5495 m), and Cape Basin (5058–5655 m) (Böggemann 2009), Brazil Basin and Argentine Basin (4481–5188 m) (Böggemann 2016), and Scotia Sea (4551–4720 m) (Böggemann and Dietz 2016).

Figures

Figure 3. Geographic distribution and median-joining COI haplotype networks for Progoniada regularis Hartman, 1965 and P.cf. regularis Hartman, 1965. The colour-code in the network corresponds to the geographic localities, each vertical line represents one mutational step and the size of each haplotype its frequency.Haplotypes are numered 1–11, details are listed in the Supporting Information, Table S2. Available data came from both the Atlantic and Pacific Oceans; the type locality of P.regularis located off New England, NE Atlantic Ocean, is indicated by an asterisk in the map.

Figure 10. LM and cLSM studies of Bathyglycinde sibogana (Augener and Peưibone in Peưibone, 1970) (A, B), SEM studies of Progoniada regularis Hartman, 1965 (C–F), and Bathyglycinde profunda (Hartman & Fauchald, 1971) (G): A, LM study of proboscidial papillae of area I and area II, median part of proboscis. B, cLSM study of similar part of proboscis.C, prostomium with extended proboscis. D, chaetigers 20–25, right side, posterior view. E, chevrons. F, proboscidial papilla. G, proboscidial papillae of areas I and II (as labelled) on posterior part of proboscis.—A, B, SMF 30491, central Atlantic.C–F, ZMH-P 26697 (SEM stub 1341), central Atlantic. G, SMF 30589 (SEM stub 1319), central Atlantic. Abbreviations: rtm = retractor muscle of proboscis, long arrows pointing to papillae of area I, arrowheads pointing to papilla of area II, asterisk marking protruding bulge on papilla of area II. Scales A, B, 50 µm; C, D, G, 100 µm; E, F, 10 µm.