Research Article |
Corresponding author: Joana Zanol ( joanazanol@mn.ufrj.br ) Academic editor: Christopher Glasby
© 2022 Joana Zanol, Pat Hutchings.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Zanol J, Hutchings P (2022) A new species of giant Eunice (Eunicidae, Polychaeta, Annelida) from the east coast of Australia. ZooKeys 1118: 97-109. https://doi.org/10.3897/zookeys.1118.86448
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A new giant species is described from New South Wales, Australia. Eunice dharastii sp. nov. differs from described Australian species and is most similar to E. aphroditois (Pallas, 1788), E. flavopicta Izuka, 1912, and E. kinbergi Ehlers, 1868. The unique combination of features that characterizes the new species is irregular articulated prostomial appendages; antennae reaching back beyond chaetiger 4; branchiae starting at chaetiger 10, initially button-shaped and distinctly longer than notopodial cirri where best developed; dorsal fleshy knobs on anterior chaetal lobes; notopodial cirri pendulous, abrupt tapering from inflated bases; bidentate compound falcigerous chaetae with both teeth directed laterally, distal tooth much shorter than proximal tooth in median and posterior chaetigers; and dark bidentate subacicular hooks starting at chaetiger 58, tapering to a small head with both teeth directed distally, and proximal tooth much larger than minute and spur-like distal tooth. This new species lives in sandy sediments in coastal waters 1–8 m deep. It is highly mobile and not easy to collect, which may explain why it was not described before.
Bobbit worm, Eunice aphroditois, Port Stephens, taxonomy
Eunice, type genus of Eunicidae, is polyphyletic and currently characterized by plesiomorphic characters, such as the presence of three antennae, a pair of palps and a pair of peristomial cirri, the absence of regular articulations on prostomial appendages, presence of limbate, thin pectinate, compound bidentate falciger or spiniger chaetae, and dark uni- or bidentate subacicular hooks (
Giant species are found in subtidal and intertidal zones of tropical and temperate oceans. The classification of these species has a long history of confusion. Many species have been synonymized with Eunice aphroditois (Pallas, 1788) (e.g.,
Giant morphs from Indian and Pacific Oceans are almost always identified as E. aphroditois (e.g.,
In this study, we describe a new species of giant Eunice from the subtidal zone of the east Australian coast (Southwest Pacific Ocean).
Specimens were collected during scuba dives at depths of 1–8 m by attracting an individual worm out of its tube through enticement with crushed pilchard, Sardinops sagax (Jenyns, 1842). Once the individual extended far enough out of the tube, it was quickly grabbed from behind the head and pulled out of its tube (see Suppl. material
Collected specimens were fixed and preserved in 95% ethanol. Preserved specimens were photographed with a Canon EOS 7D with a Macro EF 100 mm and the Spot Flex CCD 15.2 fitted on a Leica MZ16 Stereo microscope at the Australian Museum. The software Helicon Focus 5.3 was used for focus stacking. Parapodia (4, 15, 45,100, 200, 300, 400, 470) were removed from the holotype and paratype, dehydrated in ethanol, critically point dried, coated with 20 nm of gold, and examined under a JEOL JSM-6480 scanning electron microscope (SEM) at Macquarie University, Sydney. Additional parapodia (3, 80, 160, 240, 300, 380, 460) were removed, mounted in glycerine on a cavity slide and photographed using an Olympus DP 74 fitted on an Olympus Compound Microscope BX53, then the images were processed by Olympus cellSens software.
We describe the holotype and include values of paratype in parentheses. The general format of the description follows
Genus Eunice
Holotype. Australia • New South Wales, Nelson Bay, Port Stephens Main Beach; 32°42'54.91"S, 152°9'1.12"E; 8 m depth; Aug. 2012; D. Harasti leg.; AM W.53870. Paratype. Australia • 1 same data as for holotype; AM W.41747.
Australia • 1 incomplete with 80 chaetigers, 120 mm in length and 20 mm maximum width Eunice cf. aphroditois; New South Wales, Nelson Bay, Port Stephens; AM W.140.
Live specimens: iridescent reddish with lighter patches on prostomium, peristomium, and along the body (Fig.
Eunice dharastii sp. nov. A anterior end of live specimen coming out of its burrow, dorsal view B anterior end of live specimen coming out of its burrow, anterior view C anterior end, dorsal view D anterior end, lateral E anterior end, dorsal view F parapodia, chaetiger 34, anterior view G parapodia from posterior chaetiger of the fragment, anterior view H branchiae and notopodial cirrus, chaetiger 10 I parapodia, chaetiger 4, upper view J parapodia, chaetiger 90, anterior view. br, branchiae; dbl, dorsal buccal lip; dfk, dorsal fleshy knob, vbl, ventral buccal lip. I, J scanning electron microscopy. C, D holotype AM W.53870 E–J paratype AM W.41747. Scale bars: 0.2 mm (I); 1 mm (F, G, H, J); 5 mm (C, D, E).
Fixed specimens iridescent brown to purple with lighter patches. Only peristomial cirri and few notopodial cirri retain color pattern of live specimens, prostomial appendages beige (Fig.
Holotype incomplete, with 520 chaetigers, in two pieces; first with 300 chaetigers, 200 well preserved + 100 slightly flaccid, and second with 220 chaetigers, all slightly flaccid; total length 980 mm; length through chaetiger 10 20 mm; width at chaetiger 10 without/with parapodia 12/15 mm, maximum width at chaetiger 18 without/with parapodia 18/22 mm, from chaetiger 18 width fairly uniform for following 200 chaetigers. Many parapodia with broken chaetae.
Paratype incomplete with 782 chaetigers in three pieces, first with 250 chaetigers, second with 222, all slightly flaccid, and third with 310 chaetigers; total length 1170 mm; length through chaetiger 10 20 mm; width at chaetiger 10 without/with parapodia 16/19 mm; maximum width at chaetiger 100 without/with parapodia 18/23 mm. Body almost semicircular anteriorly, becoming more flattened around chaetiger 70–80.
Prostomium with dorsal buccal lips as paired median dorsal ridges, obliquely truncate, with thickened lateral margins and median sulcus narrow (Fig.
Maxillary formula 1+1, 7+7, 7+0, 4+7, 1+1, 1+1 (Fig.
Branchiae present from 10 (10) until at least chaetiger 520, end of branchiae not recorded (branchiae ends well before pygidium on chaetiger 492); first with just 1 button-shaped filament around 1/5 of dorsal cirri length (Fig.
Chaetal lobes truncate along whole fragment, posterior increasingly oblique; anterior with dorsal fleshy knob and neuroaciculae emerging posterior to it (Fig.
Slender, tapering limbate chaetae longer than all other chaetae present in all chaetigers. Pectinate chaetae thin anodont with flattened shafts; tapering smoothly subdistally or near proximal end along whole fragment (Fig.
Eunice dharastii sp. nov. (paratype AM W.41747) A maxillae, dorsal view B mandible, ventral view C subacicular hook from posterior chaetiger of the fragment D pectinate chaeta, chaetiger 200 E subacicular hook, chaetiger 300 F pectinate chaetae, chaetiger 300 G pectinate chaetae, chaetiger 240 H falciger chaetae, chaetiger 300 I falciger chaetae, chaetiger 4. Scale bars: 20 μm (D, F); 50 μm (C, E, G, H, I); 1 mm (A, B).
Posterior end of body and pygidium missing.
Water depth, 1–8 m, in tubes in coarse sand substrates; also occurs in sandy habitats to the west and east of the type locality in same depth range. Average specific density in Nelson Bay main beach 3.5 ± 0.6 individuals per 30 m2.
Nelson Bay Main Beach (32°42'54.91"S, 152°9'1.12"E), Port Stephens, New South Wales, Australia.
The species is named in honor of Dr David Harasti, who collected the specimens, donated them to the Australian Museum, and first suspected they were a species new to science.
Eunice dharastii sp. nov. is most similar to E. aphroditois, E. flavopicta Izuka, 1912 and E. kinbergi Ehlers, 1868 in having the prostomium with dorsal buccal lips as paired median dorsal ridges; MxVI present; branchiae longer than notopodial cirri, with stem much longer and thicker than filaments; pectinate chaetae thin anodonts with flattened shafts tapering smoothly subdistally or near proximal end; bidentate compound falcigers, dark paired tapering/blunt neuroaciculae and dark bidentate subacicular hooks (
Main morphological features that differentiate Eunice dharastii sp. nov. from the closest species.
Eunice dharastii sp. nov. | Eunice aphroditois (Pallas, 1788) | Eunice flavopicta Izuka, 1912 | Eunice kinbergi Ehlers, 1868 | |
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Data source | Present description |
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Type locality | Australia, New South Wales Nelson Bay, Port Stephens Main Beach | Sri Lanka | Japan1 | South Africa, Cape of Good Hope |
Irregular articulation of prostomial appendages (antennae and palps) | Present | Absent | Present | Present |
Region median and lateral antennae reach when folded back | holotype- chaetiger 4 (M), 5 (L)paratype- chaetiger 9 (M), 9 (L) | posterior end of peristomium (M, L) | chaetiger 2 (M), chaetiger 1 (L)2 | chaetiger 1 or 4 (M), chaetiger 1 (L) |
Branchiae present from chaetiger | 10 | 6 | 52 | 8–9 |
Length of best developed branchiae in relation to notopodial cirri | Distinctly longer | Distinctly longer | Distinctly longer | About as long as |
Dorsal fleshy knob on anterior chaetal lobe | Present | Absent | Absent | Absent |
Shape of notopodial cirri | Pendulous (sensu |
Smooth tapering from inflated bases | Pendulous (sensu |
Smooth tapering from slightly inflated bases |
Direction of teeth of compound chaetae | Both directed laterally | Not described | Proximal directed laterally, distal directed distally | Both directed laterally |
Relative length of distal and proximal teeth of compound chaetae | Anterior both similar in length, median and posterior distal tooth much shorted than proximal tooth | Not described | Distal tooth shorter than proximal tooth3, variation not described | Both similar in length or distal tooth longer than proximal tooth |
Shape of the distal end and direction of teeth of the subacicular hook | Tapering to small head with both teeth directed distally | Tapering to small head with both teeth directed distally | Head bent with both teeth directed laterally | Distinct head with proximal tooth directed laterally, distal tooth directed distally |
Shape and relative size of proximal and distal teeth of subacicular hook | Proximal tooth distally blunt, distal tooth minute spur-like, much smaller than proximal tooth | Both teeth distally blunt, distal tooth smaller than proximal tooth | Both teeth triangular, distal tooth much smaller than proximal tooth | Both teeth triangular, distal tooth smaller than proximal tooth |
Subacicular hook present from chaetiger, distribution | 53 or 58, uniform present in all chaetigers thereafter | 200, scattered missing in several chaetigers thereafter | Not described | 123, scattered missing in several chaetigers thereafter |
The examined specimen from Port Stephens identified as E. cf. aphroditois (
Here we describe a new Eunice species to science, which is at least 1 m long. Despite the large size and the shallow water habitat of some giant Eunice species, their diversity is not fully understood. This is due to the wide synonymizing of species, poor understanding of their biology and morphological variation, their concealed habitats, and difficulty in sampling (
Specimens from Australia identified and described as E. aphroditois (
However, the large variation in size may lead to the identification of one species as belonging to several species. Giant species are described from large specimens, but which were once small during earlier life stages (
Despite the large size of giant species, they are concealed in deep burrows from which the anterior end emerges for feeding. Other than by dredging, regular substrate sampling is unlikely to sample them. They can rapidly retreat back into their extensive burrow when sensing any vibration. Many of the reports of these large species come from dredged samples (e.g.,
We are thankful to Dr David Harasti for calculating specific density, collecting the specimens, and donating them to the Australian Museum; Sue Lindsay for making SEM and light micrographs possible; Dr Hannelore Paxton for the dissection of the jaws; Dr Carol Simon, Dr Julio Parapar, and Dr Chris Glasby for their valuable suggestions. Funding to JZ came from FAPERJ (proc. E-26/201.329/2021 and proc. E-26/010.002252/2019).
Video S1
Data type: Video file.
Explanation note: Attempt to catch a specimen of E. dharastii sp. nov.
Video S2
Data type: Video file.
Explanation note: Anterior end of E. dharastii sp. nov. live specimen coming out of burrow.