Harmothoe gilchristi Day, 1960

Miranda, Vinícius Da Rocha & Brasil, Ana Claudia Dos Santos, 2014, Two new species and a new record of Scale-worms (Polychaeta) from Southwest Atlantic deep-sea coral mounds, Zootaxa 3856 (2), pp. 211-226 : 217-219

Harmothoe gilchristi Day, 1960

Figures: 4 A–K; 5 A–C

Harmothoe gilchristi Day, 1960: 275–277 , fig. 1a–f. Day 1967: 68, fig. 1.10A–E. Barnich & Fiege 2000: 1922–1924 , fig. 17A–D. Barnich & Fiege 2003: 43–45, fig. 19A–D.

Material examined: 43 spms., 1 spm., IBUFRJ-2123, CAP-BC, 870 m, 39º 59' 30,33"W – 22º 22' 17,79"S, 11/04/ 2004, on Solenosmilia variabilis ; 3 spms., IBUFRJ-2128, CAP-BC, 867 m, 39º59'17,32"W – 22º21'54,38"S, 13/07/ 2005, on Lophelia pertusa ; 3 spms., IBUFRJ-2115, CAP-BC, 1040 m, 39º58'2,46"W – 22º25'25,72"S, 23/07/2005, on Lophelia pertusa ; 1 spm., IBUFRJ-2127, CAP-BC, 747 m, 40º49'49,47"W – 22º30'52,33"S, 17/03/2006, on Lophelia pertusa ; 4 spms., IBUFRJ-2119, ECOPROF 1, 603 m, 40º 10' 33,33”W – 22º 30' 16,96" S, 28/01/2008, on Errina sp. ; 7 spms., IBUFRJ-2120, ECOPROF 1, 617m, 40º 6' 5,13"W – 22º 22' 36,31"S, 28/01/2008, on Enallopsammia rostrata ; 5 spms., IBUFRJ-2122, ECOPROF 1, 626 m, 40º 6' 17,48"W – 22º 22' 34,34"S, 29/01/ 2008, on Enallopsammia rostrata ; 2 spms., IBUFRJ-2124, ECOPROF 2, 747 m, 40º10'33"W – 22º37'53"S, 10/06/ 2008, on Lophelia pertusa ; 1 spm., IBUFRJ-2114, ECOPROF 3, 608 m, 40º6'11,55"W –22º22'30,79""S, 05/07/ 2008, on Madrepora oculata ; 3 spms., IBUFRJ-2117, ECOPROF 4, 612 m, 40º 6' 11,04"W – 22º 22' 33,53"S, 05/ 08/2008, on Solenosmilia variabilis ; 1 spm., IBUFRJ-2102, ECOPROF 5, 603 m, 40º6'11,42"W – 22º22'31,77"S, 01/09/2008, on Solenosmilia variabilis ; 2 spms., IBUFRJ-2121, ECOPROF 6, 608 m, 40º7'21,81"W – 22º22'59,31"S, 26/09/2008, on Solenosmilia variabilis ; 1 spm., IBUFRJ-2110, ECOPROF 7, 609 m, 40º6'18,81"W – 22º22'24,43"S, 25/10/2008, on Solenosmilia variabilis ; 1 spm., IBUFRJ-2113, ECOPROF 8, 606 m, 40º6'17,87"W – 22º22'24,44"S, 21/11/2008, on Solenosmilia variabilis ; 1 spm., IBUFRJ-1974, ECOPROF 9, 639 m, 40º5'45,06"W – 22º22'41,48"S, 22/12/2008, on Solenosmilia variabilis ; 2 spms., IBUFRJ-2104, ECOPROF 10, 613 m, 40º5'42,21"W – 22º22'3,02"S, 17/01/2009, on Solenosmilia variabilis ; 1 spm., IBUFRJ-2116, ECOPROF 11, 608 m, 40º7'35,34"W – 22º24'13,33"S, 14/02/2009, on Solenosmilia variabilis ; 1 spm., IBUFRJ-2118, ECOPROF 11, 603 m, 40º7'20,69"W – 22º22'58,22"S, 14/02/2009, on Solenosmilia variabilis ; 2 spms., IBUFRJ-2111, ECOPROF 12, 628 m, 40º6'47,32"W – 22º22'53,31”S, 13/03/2009, on Solenosmilia variabilis ; 1 spm., IBUFRJ-2126, ECOPROF 13, 626 m, 40º6'45,87"W – 22º22'59,21"S, 23/04/2009, on Enallopsammia rostrata .

Diagnosis: Prostomium bilobed, with two pair of eyes: the anterior pair situated dorsolaterally at the widest part of prostomium and posterior pair at the hind margin of prostomium. Anterior margin of elytra with digitiform papillae, surface covered mainly by conical microtubercles in anterior part, becoming gradually larger and clubshaped towards the posterior margin. Parapodia biramous; notochaetae shafts with several rows of spines and a blunt tip; all neurochaetae bidentate and presenting rows of spines on the distal half of it.

Description: Specimens varying in size from 32 segments (length: 09 mm; width 04 mm) up to 46 segments (length: 24 mm; width: 07 mm), but the majority of specimens with 42 segments. Prostomium bilobed ( Fig. 4A ), with distinct cephalic peaks; median antenna missing or detached in many specimens, in all of them the ceratophore is inserted in anterior notch; lateral antennae inserted ventrally, styles with few small papillae over the surface and abruptly tapering, subdistally, to a filliform tip. Anterior pair of eyes situated dorsolaterally at the widest part of prostomium, posterior pair situated dorsally at hind margin of prostomium. Palps ventrolaterally inserted, with pointed tips. Tentaculophores inserted laterally to prostomium, each presenting two or three notochaetae; dorsal and ventral cirrus also present, styles with small papillae, tapering distally to a filliform tip. Second segment ( Fig. 4A ) with the first pair of elytra, parapodia biramous and long buccal cirri. Following segments present a tapering ventral cirrus in the parapodia.

Fifteen pairs of elytra, covering dorsum, on segments 2, 4, 5, 6, 7, and on alternating segments until segment 23, then on segments 26, 29 and 32, last segments cirrigerous. Elytra ( Fig. 4B ) presenting posterior margin with digitiform papillae, surface covered mainly by conical microtubercles ( Fig. 4C ) in anterior part of elytra, becoming gradually larger and club-shaped towards the posterior margin ( Fig. 4D ). Segments without elytra present a distinct dorsal tubercle and a dorsal cirrus, cirrostyles sparsely papillate.

Parapodia biramous ( Fig. 4E ); notopodia and neuropodia with elongate acicular lobe, neuropodia presenting a digitiform supra-acicular process; tips of notoacicula and neuroacicula extending beyond epidermis. Notochaetae stouter than neurochaetae, with distinct rows of spines and blunt tips ( Figs. 4 F–G ). All neurochaetae with distinct rows of spines and bidentate tips ( Fig. 4H–K ), the lower neurochaetae with both teeth not curving, they can be of the same size or one smaller than the other ( Figs. 4I , 5A ); middle neurochaetae with curved and blunt primary tooth ( Figs. 4J , 5B ); upper neurochaetae with curved and pointed primary tooth ( Figs. 4K , 5C ).

Remarks: This species was previously identified as Lagisca floccosa Augener, 1906 by Brasil et al. (2007), but Lagisca was later considered a junior synonym of Harmothoe by Pettibone (1953) and Barnich & Fiege (2000), which would mean that the species identified as L. floccosa should be treated as H. floccosa . However, a detailed analysis of this species and of a larger sample of other 38 specimens shows that it does not present macrotubercles over the elytra, revealing that it belongs, instead, to H. gilchristi . The misidentification of the specimens may have resulted from the fact that the microtubercles near posterior margin of the elytra are large, which could have been confused with the macrotubercles found in H. floccosa .

Of the species of Harmothoe already reported for the Brazilian coast by Amaral et al. (2013), none of them seems to be like H. gilchristi , H. aculeata Andrews, 1891 , H. ernesti Augener, 1931 and H. macginitiei, Pettibone, 1955 possess macrotubercles over the surface of the elytra. While H. lepida ( Amaral & Nonato, 1982) presents the borders of elytra smooth. According to Barnich & Fiege (2003) H. gilchristi can be easily confused with H. goreensis Augener, 1918 , but they differ from each other in the fact that H. gilchristi has all neurochaetae bidentate and conical microtubercles which become bigger and club-shaped toward the posterior margin of the elytra, while H. goreensis possess uni- and bidentate neurochaetae and only conical and never club-shaped microtubercles over the elytra.

The species H. gilchristi was originally described from South Africa ( Day 1960, 1967). Its occurrence was later extended to the Northeast Atlantic ( Brito et al. 1991) and to the Mediterranean Sea ( Barnich & Fiege 2000). Here, we provide the first record of the species for the Southwestern Atlantic, occurring at Campos Basin, off Rio de Janeiro, southeast coast of Brazil. All of the specimens were associated with the corals S. variabilis , L. pertusa , M. oculata and E. rostrata , with depth range from 605 m to 1040 m.

Habitats: The species was described as associated with cnidarian and algae species ( Isidella sp. , Cladocora caespitosa ( Linnaeus, 1767) and Dendrophyllia ramea ( Linnaeus, 1758)) and also to other substrata (sand grains and rubble). This species was previously recorded living from shallow water down to 845m, now we extend the occurrence of H. gilchristi down to 1040m and found it associated with the corals E. rostrata , S. variabilis , L. pertusa and M. oculata .

Distribution: Southwest Atlantic (Campos Basin— Brazil), Southeast Atlantic, Northeast Atlantic, and Mediterranean Sea.

Figures

FIGURE 4. Harmothoe gilchristi. (A) Dorsal view of the anterior end; (B) Middle elytron, right side; (C) Small conical microtubercles; (D) Club-shaped microtubercles; (E) Left middle elytrigerous parapodium; (F) Notochaeta; (G) Tip of same; (H) Bidentate neurochaeta; (I) Tip of lower neurochaeta; (J) Tip of middle neurochaeta; (K) Tip of upper neurochaeta (Scales bars: A: 1 mm; B, C, D: 150 µm; E: 400 µm; F, H: 200 µm; G, I, J, K: 20 µm).

FIGURE 5. Harmothoe gilchristi SEM of the neurochaeta. (A) Tip of lower neurochaeta; (B) Tip of middle neurochaeta; (C) Tip of upper neurochaeta (Scales bars: A, B= 10 µm; C= 20 µm).