Chaetopterus dewysee, Tilic & Rouse, 2020

Tilic, Ekin & Rouse, Greg W., 2020, Hidden in plain sight, Chaetopterus dewysee sp. nov. (Chaetopteridae, Annelida) - A new species from Southern California, European Journal of Taxonomy 643, pp. 1-16 : 4-12

Chaetopterus dewysee sp. nov.

urn:lsid:zoobank.org:act:B4B305E7-9A28-4632-9E58-A5A9A8E0A6D3

Figs 1–4

Chaetopterus variopedatus – Treadwell 1914: 204. — Hartman 1959: 396; 1969: 209. — Brown 1972:

278.; 1975: 136, figs 1, 4–8.; 1977: 121. — Sumida & Case 1983: 249. Chaetopterus sp. 1 – Osborn et al. 2007: 43. — Moore et al. 2017: 600. Chaetopterus sp. – Deheyn et al. 2013: 702, fig. 1. — Branchini et al. 2014: 247, fig. 2. — Shah et al.

2014: 1, figs 1, 8.; 2015: 408, figs 1–6. — Lemer et al. 2015: 175. — Rawat & Deheyn 2016: 1,

fig. 1. Chaetopterus sp. nov. – Andrade et al. 2015: 2863. Chaetopterus – Weigand et al. 2017: 1, fig. 1.; Weigand et al. 2018: 1.

Diagnosis

Chaetopterus dewysee sp. nov. is characterized by having a long u-shaped tube partly buried in sediment, 10 region A chaetigers, 11–12 club-shaped a4 cutting chaetae with dark brown, coppery metallic coloration, a patch of notopodial uncini at the upper ventral margin of the modified b3–b5 notopodia.

Etymology

Named for Mary ‘Dewy’ White, for her support of the Rouse lab and her passion for conservation and marine biological research. Based on her love of the sea we have incorporated the German word ‘See’ into the name.

Material examined

Holotype

UNITED STATES OF AMERICA • adult specimen with tube; California, San Diego, Scripps Submarine Canyon ; 32°52′11.35″ N, 117°15′36.00″ W; depth 20 m; 2019; Phil Zerofski leg.; GenBank: MN991231 ; SIO-BIC A11476 .

Paratypes

UNITED STATES OF AMERICA • 1 adult specimen; same collection data as for holotype; GenBank: MN991233 ; SIO-BIC A10193 • 1 adult specimen; same collection data as for holotype; 18 Feb. 2010; Eddie Kisfaludy leg.; GenBank: MN991236 ; SIO-BIC A4193 • 1 adult specimen; California, San Diego , La Jolla Submarine Canyon ; 24 Jul. 2008; Eddie Kisfaludy leg.; GenBank: MN991230 ; SIO-BIC A11649 • 1 adult specimen; same collection data as for holotype; 2017; Greg Rouse leg.; GenBank: MN991235 ; SIO-BIC A11652 • 1 adult specimen; California, San Diego, Scripps Institution of Oceanography pier; Nov. 2017; Avery Hatch and Ekin Tilic leg.; GenBank: MN991234 ; SIO-BIC A11653 • 1 adult specimen; same collection data as for preceding; 5 Jul. 2019; Ekin Tilic leg.; SIO-BIC A12034 (cybertype) .

Cybertype

Complete micro-CT scan of a paratype SIO-BIC A12034 , designated as cybertype.

Direct link to online specimen: www.morphdbase.de/?E_Tilic_20200122-S-5.1

Direct links to the micro-CT stack:

PART 1/3: www.morphdbase.de/?E_Tilic_20200122-M-42.1

PART 2/3: www.morphdbase.de/?E_Tilic_20200122-M-41.1

PART 3/3: www.morphdbase.de/?E_Tilic_20200122-M-40.1

Direct link to 3D surface rendering: www.morphdbase.de/?E_Tilic_20200122-M-43.1

Description

Total body length of holotype 55 mm (paratypes: A12034 = 35 mm, A11652 = 180 mm, A11653 = 107 mm). Region A with 10 chaetigers. Prostomium small, with anterior border rounded, entire. Peristomium extended, completely covering prostomium; wide horseshoe-shaped in anterior view ( Figs 2A , 4C ). Two grooved palps extending beyond peristomium, length 7.5 mm ( Fig. 2A ). Paired eyes present, located at the base of palps ( Fig. 2B ). Middorsal ciliated groove (cg) extending from region B through region A, ending near the mouth opening with a conical ridge ( Fig. 2 C–B). Ventral surface of region A with a smooth plastron (ventral shield) ( Figs 1A , 4B ): length 9 mm, width 3.9 mm. First 9 chaetigers uniramous. Tenth chaetiger (a10) biramous, with long notopodium and a neuropodial lobe ( Fig. 3A ). Each notopodium with 2–3 rows of light yellow lanceolate chaetae. Neuropodial uncini of chaetiger a10 with 5–6 teeth, short rostral and long adrostral process ( Fig. 3B ). Chaetiger a4 with 11–12 modified cutting chaetae ( Fig. 2 C–E). Modified chaetae dark brown, with coppery metallic shimmer, club-shaped, tip asymmetrical, truncated with sharp apical point ( Fig. 2E ). Larger portion of cutting chaetae embedded inside the chaetiger ( Figs 2D , 4E ). Region B with five chaetigers, with biramous parapodia. Digestive gland blackish green in living specimens; coloration lost in ethanol-preserved specimens. Chaetiger b1 with distally tapering, aliform notopodia extending to the middle of region A ( Figs 2C , 3D ): length 9.2 mm (paratypes: A12034 = 11 mm, A11652 = 28 mm, A11653 = 26.4 mm). Chaetiger b2 modified with large cupule ( Figs 2A , 4 A–B). Notopodia of b3–b5 fused middorsally, forming enlarged fans ( Figs 2A , 4A ). Small pocket with patch of uncini at the upper ventral margin of the enlarged fan ( Fig. 3C, E ). Notopodial uncini of chaetigers b3–b5 with 9–10 teeth, shorter adrostral process and a long rostral process ( Fig. 3F ). Neuropodium of chaetiger b1 with upper and lower row of uncini ( Fig. 3D ), b3–5 only with one lower row of uncini ( Fig. 3C ). Region C with 16 chaetigers (paratypes: A12034 = 10, A11652 = 19, A11653 = 17). Parapodia biramous. Notopodia long, with distally tapering tip and internal acicular chaetae ( Fig. 3G ). Neuropodia bilobed; lateral lobe with no cirrus on lateral side; ventral neuropodial lobe without cirrus ( Fig. 3G ). Lateral lobe uncini of region C arranged in 2–3 rows ( Fig. 3H ), chaetiger c1 uncini similar to those of chaetiger a10, with 5–6 teeth ( Fig. 3I ).

Tube

Parchment like, U-shaped tube, sometimes with sand debris and shell fragments on the outer surface ( Fig. 1B ). Both tube openings almost half in diameter (8 mm) compared to the middle section of the tube (16 mm). Total tube length 293 mm.

Habitat

Commonly found partially buried along canyon walls in large assemblages of solitary, intermingled tubes and sediment with other fauna, such as sponges and tunicates.

Distribution

Southern California. COI sequences confirm the identity of Chaetopterus sp. 1 from Santa Barbara ( Osborn et al. 2007; Moore et al. 2017) as C. dewysee sp. nov. ( Fig. 5 )

Molecular information

All type specimens of Chaetopterus dewysee sp. nov., except for the cybertype, were subsampled and sequenced for COI ( Table 1 ). The specimen chosen for the micro-CT scan was kept intact as a cybertype. All COI sequences for specimens identified as Chaetopterus dewysee sp. nov. were>98.8% similar. These included the COI sequence pulled from the available Chaetopterus transcriptome, the sequence from Santa Barbara, published by Osborn et al. (2007) and the COI sequence from the larva ( Fig. 1C ). The haplotype network for the nine C. dewysee sp. nov. sequences ( Fig. 5 ) shows minor variation amongst the specimens. The most frequent haplotype is shared by four individuals (the sequenced larva, the holotype A11476 , A10193 and A11653 ). In addition to this, there are 5 low-frequency haplotypes, each represented by a single specimen. The haplotypes are separated by one to three mutational steps. On the maximum likelihood tree sequences that were more than 97% similar were given the same terminal name and the branches were collapsed ( Fig. 5 ). Average identity between the COI sequences of different Chaetopterus spp. was 78.7% (min. 72.1%, max 85.2%).

Remarks

Chaetopterus dewysee sp. nov. most resembles the two European species, C. brevis Lespés, 1872 and C. variopedatus . The main difference between the 3 species is in the morphology of a4 cutting chaetae. Chaetopterus variopedatus has a4 cutting chaetae with teeth, whereas the cutting chaetae of C. brevis are symmetrical and distally inflated. In C. dewysee sp. nov. the cutting chaetae have a smooth, asymmetrical tip with a sharp apical point. Furthermore, region C notopodia of C. dewysee sp. nov. have no lateral cirrus, which is present in both C. brevis and C. variopedatus . Chaetopterus brevis also differs from the other two species in having a gregarious habit, that can be occupied by multiple individuals. Relationships were not supported across most of the phylogeny generated here using COI ( Fig. 5 ). Chaetopterus dewysee sp. nov. is sister group to Chaetopterus cf. brevis from France, but with low support. In Moore et al. (2017), which also used nuclear 18S and 28S data, this relationship was also recovered, but with very strong support.

Other Chaetopterus species described from the eastern Pacific (Galapagos Islands) are C. galapagensis Nishi, Hickman & Bailey-Brock, 2009 , C. adunctus Nishi, Hickman & Bailey-Brock, 2009 and C. charlesdarwinii Nishi, Hickman & Bailey-Brock, 2009 . Chaetopterus adunctus has a J-shaped and C. darwinii a U-shaped tube, both attached to rocks ( Nishi et al. 2009), whereas the new species C. dewysee sp. nov. has tubes partly buried in sediment. The obvious main difference among the species is the number of region A chaetigers: C. charlesdarwinii only has 9, C. galapagensis 13–15 and C. dewysee sp. nov. has 10. The three species also differ in the number of teeth on the chaetiger c1 lateral lobe uncini; C. dewysee sp. nov. only has 5–6 teeth whereas C. adunctus has 10–11, C. charlesdarwinii has 9–11 and C. galapagensis 7–8 teeth ( Nishi et al. 2009).

Figures

Fig. 1. Chaetopterus dewysee sp. nov. A. Live photograph of a paratype (SIO-BIC A11652), showing the three morphologically distinct regions of a chaetopterid annelid; a = region A, b = region B, c = region C. B. Holotype together with its tube (SIO-BIC A11476). C. Larva of Chaetopterus dewysee sp. nov. collected from a plankton sample off La Jolla and sequenced (GenBank: MN991232). D. Habitat of the new species, tubes are marked with arrow-heads.

Fig. 2. Chaetopterus dewysee sp. nov. A. Habitus of a paratype (SIO-BIC A11653). B–C. Anterior region A, chaetigers are numbered a1–10. D–E. Details of chaetiger a4 cutting chaetae; * marks a developing cutting chaeta. p = palps, ey = eyes, cg = ciliated groove, nt = notopodium.

Fig. 3. Chaetopterus dewysee sp. nov. A. Biramous chaetiger a10 parapodium with a long notopodium and a neuropodial lobe. B. Neuropodial uncinus of chaetiger a10. C. Chaetiger b3 neuropodium with one row of uncini, arrow-head marks the patch of uncini (E) at the upper ventral margin of enlarged fan. D. Aliform notopodium of chaetiger b1. F. Notopodial uncinus of chaetiger b3. G. Biramous region C parapodia. H. Uncini of region C lateral lobe arranged in 2–3 rows. I. Chaetiger c1 uncinus of lateral lobe.

Fig. 4. Chaetopterus dewysee sp. nov. micro-CT surface renderings of the cybertype (SIO-BIC A12034). A. Dorsal view of the whole specimen. B. Lateral view of the whole specimen. C. Frontal view with virtual dissection planes (I–III) showing cross-sections along the body. D–E. Lateral view with a virtual dissection window showing the parapodial musculature of region A. Direct link to cybertype: www.morphdbase.de/?E_Tilic_20200122-S-5.1

Fig. 5. Maximum likelihood tree of Chaetopterus Cuvier, 1830 spp. COI sequences with the Mesochaetopterus Potts, 1914 clade as outgroup, based on Moore et al. (2017). Only bootstrap supports>80 are shown. The new species Chaetopterus dewysee sp. nov. and C. variopedatus (Renier, 1804) from the type locality are in bold. Number of sequences included for each terminal is in brackets. Details on sequences that were analyzed can be found in Table 1. Haplotype network for the nine Chaetopterus dewysee sp. nov. sequences is shown next to the tree.