Harmothoe impar ( Johnston, 1839 )

Barnich, Ruth & Fiege, Dieter, 2009, Revision of the genus Harmothoe Kinberg, 1856 (Polychaeta: Polynoidae) in the Northeast Atlantic, Zootaxa 2104 (1), pp. 1-76 : 48-50

Harmothoe impar ( Johnston, 1839)

( Figs. 3 ; 23A–J )

Polynoe impar Johnston, 1839: 436 , pl. 22 figs. 3–9.

Harmothoe impar: Fauvel (1923) : 59, fig.21a–f [part]; Hartmann-Schröder (1996): 48, fig. 13 [part]; Chambers & Muir (1997): 106, fig. 27; Barnich & Fiege (2000): 1906 , fig. 9A–D; Barnich & Fiege (2003): 48, fig. 23A–D.

Polynoe reticulata Claparède, 1870: 374 , pl. 1 fig. 1a–f; Marenzeller (1874): 412; Bobretzky (1882): 185.

Harmothoe reticulata: Fauvel (1923) : 61, fig. 22f–l.

Lagisca elisabethae McIntosh, 1900: 303 , pl. 27 fig. 3, pl. 32 fig. 6, pl. 38 figs. 4–6.

? Tricosmochaeta trilobocephala Morgera, 1918: 1 , pl. 1 figs. 1–13.

? Harmothoe boholensis: Rullier, 1963: 177 [not Polynoe boholensis Grube, 1878 ].

Type material. Harmothoe impar : neotype, designated here, NMSZ 2009 038 (selected out of 2 spms., NMSZ 2009 039), Berwick-upon-Tweed, Bucket Rocks, lower shore, under rocks, 55°46.5’N 1°59’W, 28 March 1998, leg. S.J. Chambers.

Lagisca elisabethae : 2 syntypes (af), BMNH 1921.5 .1.308, Scotland, St. Andrews , 1870, from débris brought by fishing-boats from offshore waters (all elytra lost) .

Additional material. NE Atlantic: 1 spm., NMSZ 2009 039, Berwick-upon-Tweed , Bucket Rocks, lower shore, under rocks, 55°46.5’N 1°59’W, 28 March 1998, leg. S.J. Chambers. 1 spm., NMSZ 2009 040, Berwick-upon-Tweed , Meadow Heaven, Laminaria holdfasts, 31 March 1998, leg. S.J. Chambers. 5 spms., NMS.Z.1983.65.09, Tyne and Wear, Cullercoats, mid tide level and below, under stones and boulders, May 1979, leg. P.R. Garwood. 1 spm., SMF 17301, France, Baie de Morlaix , Pierre Noire, 15 April 2003, 10 – 20 m, dredge Picard , leg. & ded. C. d’Udekem d’Acoz. 2 spms., SMF 13192, France, Roscoff, 18 March 2003, between Laminaria rhizomes, leg. C. Bleidorn. 3 spms., SMF 13193, France, Roscoff , 19 March 2003, between Laminaria rhizomes, leg. C. Bleidorn. 2 spms., SMF 13194–13195, France, Roscoff , March 2003, between Laminaria rhizomes, leg. C. Bleidorn. 4 spms., SMF 12424, France, Presqu'île de Quibéron , Pointe du Congruel, intertidal, under stones, 08 April 1997, leg. C. d’Udekem d’Acoz. 5 spms., SMF 13292, France, Piriac-sur-mer ( Britany ), intertidal, 06 April 1997, leg. C. d’Udekem d’Acoz.

Diagnosis. Anterior pair of eyes dorsolateral at widest part of prostomium. Elytral margin with claviform fringing papillae; surface covered by globose to conical microtubercles; macrotubercles conical, in a row near posterior margin; tubercles often grouped on mounds, others isolated giving surface a reticulate appearance.

Description (based on neotype of H. impar ).

Body with 37 segments. At anterior end ( Fig. 23A ), prostomium bilobed, with distinct cephalic peaks; ceratophore of median antenna in anterior notch, lateral antennae inserted ventrally, styles of antennae papillate, abruptly tapering subdistally to filiform tip; anterior pair of eyes situated dorsolaterally at widest part of prostomium, posterior pair dorsally near hind margin of prostomium; palps papillate, tapering.

Tentaculophores inserted laterally to prostomium, each with two notochaetae and a dorsal and ventral tentacular cirrus, styles of cirri papillate, abruptly tapering subdistally to filiform tip. Second segment with first pair of elytra, biramous parapodia, and long buccal cirri. Following segments with tapering, short ventral cirri.

Fifteen pairs of elytra, covering dorsum, on segments 2, 4, 5, 7, then on every second segment to 23, 26, 29, 32; last five segments cirrigerous; elytral margin with claviform fringing papillae; surface covered by globose to conical microtubercles; macrotubercles conical, in a row near posterior margin; tubercles often grouped on mounds, others isolated giving surface a reticulate appearance (distinct on clean elytra!) ( Fig. 23B,C ). Cirrigerous segments with distinct dorsal tubercles; dorsal cirri with cylindrical cirrophore, style papillate, abruptly tapering subdistally to filiform tip.

Parapodia biramous; notopodia with elongate acicular lobe; neuropodia with elongate prechaetal acicular lobe with short, digitiform supra-acicular process; neuropodial postchaetal lobe shorter than prechaetal lobe, rounded; tips of noto- and neuroacicula penetrating epidermis ( Fig. 23D ). Notochaetae slightly stouter than neurochaetae; with distinct rows of spines and blunt tip ( Fig. 23E,F ); neurochaetae with distinct rows of spines, tips of upper and some middle bidentate, of other middle and lower unidentate ( Fig. 23G–J ).

Measurements. Neotype of H. impar, NMSZ 2009 038 ( Fig. 23A–J ): L 14 mm, W 3.5 mm for 37 segments. Additional specimens, NMSZ.1983.65.09: largest L 16 mm, W 4 mm for 37 segments, smallest L 9 mm, W 2.5 mm for 34 segments.

Remarks. Harmothoe impar ( Johnston, 1839) is, together with H. imbricata ( Linnaeus, 1767) and H. extenuata ( Grube, 1840) , one of the oldest Harmothoe species ever described. As for all these species, no type specimens are available, neither in the British nor in other museums, and the original description is insufficient for differentiation from other species occurring in the region. Since H. impar is a common littoral species and the name is widely used in the literature, we decided to designate and describe a neotype selected from several specimens in good condition from the type locality Berwick-upon-Tweed.

As indicated in Fig. 23B,C , elytral macrotubercles of H. impar specimens from the Northeast Atlantic are rather prominent. In Mediterranean specimens however, macrotubercles might be less conspicuous (see Barnich & Fiege 2000 and 2003). But the presence of elytral tubercles grouped on mounds, giving the elytron a reticulate appearance, is a very striking character, allowing identification of H. impar specimens in any case. Although the two syntypes of Lagisca elisabethae McIntosh, 1900 have lost their elytra today, the typical reticulate pattern of the elytra was described by McIntosh (1900), thus leaving no doubt on the synonymy with H. impar . The possible synonymy of Tricosmochaeta trilobocephala Morgera, 1918 and specimens reported by Rullier (1963) as Harmothoe boholensis (Grube, 1878) has been discussed in detail in Barnich & Fiege (2000).

Distribution. Northeast Atlantic, North Sea, Skagerrak to the Kieler Bucht, and Mediterranean Sea. Habitat. On rocky shores between algae, in shallow waters.

Figures

FIGURE 3. Identification characters of Harmothoe impar, H. clavigera, H. rarispina, H. extenuata, H. fragilis, H. vesiculosa, H. abyssicola, and H. mariannae n. sp.

FIGURE 23. Harmothoe impar (neotype, NMSZ 2009 038). (A) anterior end; (B) right 2nd elytron from segment 4; (C) detail of posterior margin of same; (D) right elytragerous parapodium from segment 15, posterior view; (E) distal half of long notochaeta; (F) tip of same; (G) distal part of middle neurochaeta; (H) tip of same; (I) tip of upper neurochaeta; (J) tip of lower neurochaeta. (Scales: A = 1 mm; B= 500 µm; C, E, G = 100 µm; D = 250 µm; F, H–J = 50 µm).