Lepidonotus tenuisetosus
Creators: name: Chaibi, Marwa
name: Azzouna, Atf
name: Martin, Daniel
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Annelida
Polychaeta
Phyllodocida
Polynoidae
Lepidonotus
Lepidonotus tenuisetosus

description: Lepidonotus tenuisetosus (Gravier, 1902)
Euphione tenuisetosa. Gravier (1902): 222 -226, textfigs. 228-231, pl. 8 figs. 123-126.
Lepidonotus tenuisetosus. (Wehe, 2006); 107-109, fig. 24 a-l. Non Barnich & Fiege (2003): 86, fig. 44; non Çinar (2009): 2286, fig. 2A.
Material examined. CEAB.AP.985, 30 specimens, collected from Mars 2018 to Mars 2019 in Radès Area, Gulf of Tunisia (36.809424 N; 10.285653 E) by Marwa Chaibi, preserved in 70% ethanol.
Additional material. NHMR, PMR- 17630, 1 specimen, preserved in 70% ethanol, Croatia, Adriatic Sea, 30/07/2007, collected by B. Mikac. HCMR _ Nag _ EL_01_2008_0185 and _0194, 2 specimens, preserved in 96% ethanol, 18/06/2008, rocky substrate with photophilic algae, (35.4233°N, 24.9838°E), Crete, collected by G. Chatzigeorgiou.
Description. Complete specimens with body 7.5-18.5 mm long, 1.36-2.44 wide (without parapodia), 2.08-4.08 mm wide (with parapodia) with 26 segments (25 chaetigers); elongated, flattened dorsoventrally (Fig. 2 A-B), subrectangular in cross-section. Prostomium bilobed, without cephalic peaks; median antenna smooth, with ceratophore in anterior notch, fused to prostomium, style smooth, gradually tapering, without subterminal swelling; lateral antennae smooth, inserted terminally, with ceratophores fused to prostomium, styles smooth, tapering progressively, without subterminal swelling; palps smooth and gradually tapering (Fig. 2 C-E). Two pairs of eyes close to each other, dorsolaterally on widest part of prostomium (Fig. 2C). Facial tubercle present. Pharynx with 18 big, conical, terminal papillae (Fig. 2 D-F). Tentaculophores inserted laterally to prostomium, with few chaetae and a pair of dorsal and ventral tentacular cirri with smooth, gradually tapering styles. Second segment with first pair of elytra, sub-biramous parapodia and long, tapering, ventral cirri. Twelve pairs of elytra (Fig. 1A) on elytrophore segments (Fig. 3A) (2, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23), fully covering body dorsally; first pair round, second reniform (Fig. 2G), then progressively oval (Fig. 2H); with marginal fringing papillae, mostly digitiform but with some small, globular (Fig. 2I); surface with some central and posterior small macrotubercles with blunt or warty tips (Fig. 2I, 2J) and conical to cylindrical microtubercles (Fig. 2 I-2K). Cirrophorous segments with dorsal cirri with smooth styles, gradually tapering, without subterminal swelling, reaching beyond tips of neurochaetae; styles of ventral cirri smooth, tapering, shorter than neuropodia; nephridial papillae well-visible, digitiform (Fig. 3B). Parapodia sub-biramous, noto- and neuropodia with elongate acicular lobe; tips of noto- and neuroacicula penetrating epidermis (Fig. 3A, 3B). Notochaetae slender, with numerous rows of small spines and tapering, capillary tips (Fig. 4A, 4B); neurochaetae of chaetiger 1 (i.e., second segment) slender than those of remaining chaetigers, with numerous rows of spines, similar to notochaetae but shorter (Fig. 3C); from chaetiger 3, all neurochaetae with unidentate tips, stouter than notochaetae, falcate, with numerous rows of spines in distal region (Fig. 3D). Nephridial papillae from segment 8 (chaetiger 7) onwards.
Remarks. The specimens from Tunisia fully agree with the original description by Gravier (1902), except for the special neurochaetae of chaetiger 1 (i.e., segment2), which do not show the terminal tuft of long, tight filiform extensions illustrated by Gravier (1902) in his fig. 231. Particularly, our specimens agree with the revision of types and additional materials by Wehe (2006), (Tables 1 and 2, Fig. 5 A-5E), including the shape of the neurochaetae of chaetiger 1, which he described as “ Neurochaetae of second segment altered (Fig. 24 l), more slender, with more numerous rows of spines and fine tips ” and illustrated in his figure 24 l as lacking the terminal tuft of filiform extensions (Wehe, 2006). Conversely, they differ from the Sinai specimens reported by Barnich & Fiege (2003), specifically in the shape of the antennae and dorsal cirri, in the eye position, the types of micro- and macrotubercles and the shape of neurochaetae tips (Fig. 5 F-5I), which fully agree with the features of L. carinulatus (Tables 1 and 2, Fig. 5 J-Q).
The very small specimen (i.e., an anterior fragment with only eight chaetigers, measuring about 1.6 mm long and 0.4 mm wide) reported as L. tenuisetosus from the Croatian coasts of the northern Adriatic Sea is in very poor conditions, lacking elytra and all appendages (Fig. 6A, 6B). However, the chaetae are well-visible, being uni-and bidentate, with several rows of spines and the distal ones much longer than the basal ones (Fig. 6 C-6E). Therefore, if it belongs to Lepidonotus (which cannot be confirmed considering its present conditions), it could be L. carinulatus, but certainly not L. tenuisetosus.
The specimens from Crete show unidentate chaetae, but the antennae and cirri have distal swellings and pigmented bands and, most importantly, the elytra have smooth margins (Fig. 7 A-7E). Therefore, they belong to L. clava.
Upon the authors’ request, M. E. Çinar re-examined the specimens from Mersin Bay in Turkey – ESFM-POL/05-547 (n=17, 18/09/2005, K15, 0.2= 3 m, stones with algae, approx. (36.7167°N, 34.5°E). Mersin Bay) and ESFM-POL/2005-547 (n=1, 19/09/2005, K17, 0.1-2 m, stones with algae, approx. 36.4833°N, 34.1833°E). Although all specimens show unidentate chaetae with all spines of a similar size, the eyes are not in dorsolateral position and the elytra show filiform papillae, which allow us confirming them as not belonging to L. tenuisetosus, being likely a different introduced or undescribed species that will require further analyses to be defined (M.E. Çinar, personal communication).
Finally, the specimens included in the faunal list of the invertebrates from the bottoms surrounding mammal bones experimentally deployed in Blanes Bay (Appendix S 1 in Taboada et al., 2016) are probably lost and their identification was just tentative (S. Taboada, personal communications). Therefore, its real identity cannot be currently determined and further sampling is required to confirm which species is present in Blanes Bay. However, it must be taken into account that previous studies only reported L. clava (e.g., Camp, 1976; Campoy & Jordana, 1978; Martin, 1987; Plyuscheva & Martin, 2009).
Distribution. Gulf of Aden, Red Sea, and Arabian Sea (Gravier, 1902; Wehe, 2006); Gulf of Tunisia, Mediterranean Sea (present study). Doubtful records: India, Vietnam, South China Sea, and New Caledonia (Uschakov, 1982; Hanley, 1992; Barnich et al., 2004; Wehe, 2006). Previous records from Croatia (Mikac, 2015; Mikac et al., 2020), Greece (Chatzigeorgiou et al., 2016; Faulwetter et al., 2017), Turkey (Çinar, 2009; Çinar et al., 2021), and Israel (Barnich & Fiege, 2003; Zenetos et al., 2010; Çinar, 2013) are discarded according to our results.
Habitat. Common on rocks (Red Sea); found on a rocky bottom among algae (Tunisia). 0-0.5 m depth.
description: Published as part of Chaibi, Marwa, Azzouna, Atf & Martin, Daniel, 2023, First record of Lepidonotus tenuisetosus (Annelida: Polynoidae) from Tunisia with distributional notes Abstract, pp. 7-18 in Mediterranean Marine Science 24 (1) on pages 9-13, DOI: 10.12681/mms.30404, http://zenodo.org/record/11989992