Fimbriosthenelais longipinnis ( Grube, 1869 )

Barnich, Ruth & Haaren, Ton Van, 2021, Revision of Sthenelais Kinberg, 1856, Fimbriosthenelais Pettibone, 1971 and Eusthenelais McIntosh, 1876 (Polychaeta, Sigalionidae) in the Northeast Atlantic, European Journal of Taxonomy 740, pp. 138-171 : 158-160

Fimbriosthenelais longipinnis ( Grube, 1869) (emended)

Figs 5E , 7

Sthenelais longipinnis Grube, 1869: 493 .

Sthenelais variabilis Potts, 1910: 349 , pl. 19 fig. 22, pl. 21 fig. 63 [part; var. glabra].

Sthenelais dubiosa Horst, 1917: 111 , pl. 22 fig. 7.

Fimbriosthenelais longipinnis – Pettibone 1971: 26, figs 15–17. — Aungtonya 2002: 217, figs 7–8. — Barnich & Fiege 2003: 117, fig. 58. — Wehe 2007: 64, fig. 5. — Gil 2011: 940 (?part, see remark below). — Aungtonya & Eibye-Jacobsen 2018: 3, figs 1–2.

Diagnosis

Dorsal cirri absent on segment 3. Ventral body surface finely papillated. Outer elytral margin with filiform papillae, elytral surface with rounded to conical microtubercles (in anterior elytra surface completely covered, in middle and posterior elytra microtubercles confined to areas near margins). Neuropodial posterior bracts bilobed. Parapodial stylodes distinctly papillated.

Type material

The holotype of Sthenelais longipinnis was investigated by Pettibone (1971) and Wehe (2007), all others by Pettibone (1971).

The respective type localities are: Sthenelais longipinnis (Red Sea) , S. variabilis ( Maldive Islands, Hulule, Male Atoll, Indian Ocean), S. dubiosa ( Indonesia, Indo-Pacific, several localities: Bay of Badjo, W Flores; Kwandang Bay; E of Dangar Besar, Saleh Bay).

Other material (examined)

CYPRUS • 3 specs; E Mediterranean Sea , Akrotiri Bay ; stn CY08 SB76B; depth 55 m; 13 Feb. 1968; EtOH preserved; SMF 10597. ( Fig. 7 ; see also Barnich & Fiege 2003)

JORDAN • 1 spec.; Red Sea , Gulf of Aqaba , in front of Marine Science Station; on corals and stones; 8–10 m depth; 23 Mar. 2007; EtOH preserved; SMF 19366 (original identification by T. Wehe) • 1 spec.; Red Sea , Gulf of Aqaba , in front of Marine Science Station; in sea grass meadow; 22.5 m depth; 25 Mar. 2007; EtOH preserved; SMF 19394 (original identification by T. Wehe) .

SAUDI ARABIA • 1 spec.; Red Sea , Farasan Islands , Rabigh , coast guard station ; stn RSS1 2011-1; 22°58′ N, 38°50′ E; 3–4 m depth; 7 Apr. 2011; EtOH preserved; SMF 24345 (see also Wehe 2017). ( Fig. 5E )

Description

PROSTOMIUM. Median antenna with moderately long, smooth, tapering style; ceratophore with large auricles. Lateral antennae fused to inner dorsal side of tentaculophores, very short, not reaching half the length of dorsal tentacular cirri. Two pairs of eyes present.

TENTACULOPHORES. Dorsal tentacular cirri longer than median antenna, of similar shape. Ventral tentacular cirri about half the length of dorsal ones.

ELYTRA. With filiform and shorter, clavate papillae on outer lateral margin; surface of anterior elytra completely covered by rounded to conical microtubercles, in more posterior elytra microtubercles confined to areas near margins ( Fig. 7A–B ).

CIRRI. Dorsal cirri absent from segment 3. Ventral cirri with basal knob, without long basal papillae.

PARAPODIA. Stylodes more or less club-shaped, with large, obvious papillae ( Fig. 5E ). Parapodia of anterior and middle body with stylodes present on anterior side of notopodial bract, on neuropodial acicular lobe and on upper and lower parts of bilobed posterior neuropodial bract. Margins of neuropodial anteroventral bract with digitiform extensions, anterodorsal bract reduced, without stylodes or extensions ( Fig. 7C ).

CHAETAE. Notochaetae slender, spinous, tapering to simple capillary tip. Upper neurochaetae mainly slender compound falcigers with multi-articled blade and minutely bidentate tip and a few simple, spinous chaetae. Middle neurochaetae stout compound falcigers with short single- or up to three-articled blade and bidentate tip. Lower neurochaetae slender compound falcigers with multi-articled blade and minutely bidentate tip.

BODY SURFACE. Usually finely papillated ventrally.

SIZE. Length more than 30 mm, width up to 5 mm for more than 80 segments (see Pettibone 1971). Specimens figured: SMF 24345 ( Fig. 5E ): complete specimen, strongly coiled, length and number of segments not determined, width 2.5 mm; SMF 10597 ( Fig. 7 ): anterior fragment, width 2 mm for 23 segments.

Remarks

The description above is emended for the details regarding the shape and size of the stylodes and their associated papillae and for the terminology used in the description of the neuropodial bracts. The species has been extensively studied by Pettibone (1971), Wehe (2007) and Aungtonya & Eibye-Jacobsen (2018); please refer to these works for additional details.

Specimens from the Western Mediterranean described by Gil (2011) seem to agree with F. longipinnis as described by Pettibone (1971) regarding their elytral characters and the finely papillated ventral body surface. However, they seem to differ due to a reduced number of stylodes (and those present having no papillae, but just sensorial hairs) and blades of falcigers with not more than three articles. Because of the confusing terminology regarding extensions and papillae on bracts, lobes and stylodes (see above), it is likely that the stylodes described by Gil (2011) as lacking papillae and having just hairs correspond to the extensions of the anteroventral bract. As mentioned by Pettibone (1971) the number of articles of the blades is rather variable and would also fit the current concept of F. longipinnis . Another possibility is that the specimens are juveniles of either F. longipinnis or maybe F. zetlandica . Unfortunately, those animals were not available for study and thus we cannot confirm the presence of this species in the Western Mediterranean.

The specimens of F. longipinnis from Cyprus (Eastern Mediterranean), described by Barnich & Fiege (2003) and re-investigated herein, agree in all characters with Pettibone’s revised description.

Sthenelais minor var. digitata Fauvel, 1919 was considered a possible synonym of F. longipinnis by Pettibone (1971). At the time of her revision no type material was available, but Wehe (2007) was able to examine the holotype and placed Sthenelais minor var. digitata in synonymy with Fimbriosthenelais hirsuta ( Potts, 1910) .

Distribution and habitat

Not known to occur in the Northeast Atlantic; presence confirmed for the Eastern Mediterranean Sea. Otherwise widely reported from the Red Sea and Indo-Pacific. Type of habitat unknown; in shallow water down to 75 m depth (see Pettibone 1971; Barnich & Fiege 2003).

Figures

Fig. 5. Comparison of stylodes. A–D. Sthenelais boa (Johnston, 1833), TUM 39683. A. Large specimen, width 6 mm, segment 21. B. Same, segment 4. C. Medium specimen, width 4 mm, segment 21. D. Small specimen, width 3 mm, segment 21. E. Fimbriosthenelais longipinnis (Grube, 1869), SMF 24345, width 2.5 mm, segment from mid-body. F. Fimbriosthenelais zetlandica (McIntosh, 1876), TUM 36747, width 4 mm, segment 20. Scale bar: 50 µm.

Fig. 7. Fimbriosthenelais longipinnis (Grube, 1869). SMF 10597. A. Right elytron of segment 11. B. Outer lateral margin of same. C. Left parapodium of segment 10, posterior view. Scale bars: A=500 µm; B=100 µm; C=250 µm.