Streptodonta fauchaldi, Paresque, Karla, Fukuda, Marcelo Veronesi, Martín, Guillermo San & Nogueira, João Miguel De Matos, 2015

Paresque, Karla, Fukuda, Marcelo Veronesi, Martín, Guillermo San & Nogueira, João Miguel De Matos, 2015, Amblyosyllis, Eusyllis, Odontosyllis, Perkinsyllis and Streptodonta (Annelida: Syllidae) from Brazil, with descriptions of two new species and new records for the country, Zootaxa 4000 (3), pp. 301-334 : 326-331

Streptodonta fauchaldi sp. n.

Figures 15–18 ; Table 2

Material examined. Project ' Habitats'. 21°11'0"S 40°28'27"W, 26 m: 1 specimen ( MZUSP 2710), 0 5 March 2009; 21°11'1"S 40°28'28–29"W, 26 m: 4 specimens ( MZUSP 2712, ZUEC-POL 315), 21 July 2009; 21°17'25"S 40°54'7"W, 15 m: 1 specimen ( MZUSP 2705), 0 8 March 2009; 21°17'51"S 40°30'59"W, 29 m: 1 specimen (ZUEC-POL 309), 0 7 March 2009; 21°22'58"S 40°19'44"W, 53 m: 2 specimens ( MZUSP 2713), 21 July 2009; 21°28'2"S 40°56'20"W, 16 m: 1 specimen (ZUEC-POL 308), 10 March 2009; 21°44'19"S 40°17'15"W, 50 m: 1 specimen (ZUEC-POL 312), 0 9 March 2009; 21°44'39"S 40°43'8"W, 21 m: 1 specimen ( MZUSP 2709), 19 July 2009; 21°45'14"S 40°14'7"W, 67 m: 1 specimen ( MZUSP 2707), 14 March 2009; 21°45'15"S 40°14'8"W, 66 m: 2 specimens (ZUEC-POL 311), 0 8 July 2009; 22°11'59"S 40°32'8"W, 68 m: 3 specimens ( MZUSP 2706, ZUEC- POL 310), 15 March 2009; 22°12'37–38"S 40°13'18–19"W: 2 specimens ( MZUSP 2711, ZUEC-POL 313); 22°23'22"S 40°34'59"W, 110m: 1 specimen (ZUEC-POL 314), 25 Jul 2009.

Type series. All specimens collected by the Project ' Habitats ', off Rio de Janeiro, Campos Basin. Holotype ( MZUSP 2714) and paratype 1 (ZUEC-POL 316) collected 21°33'52–53"S 40°42'53–55"W, 21–22 m, 10 March 2009. Paratype 2 ( MZUSP 2716) collected 21°24'45"S 40°25'19"W, 32 m, 20 July 2009. Paratype 3 ( MZUSP 2717) collected 21°44'42"S 40°43'9"W, 22 m, 11 March 2009. Paratype 4 (ZUEC-POL 317) and two paratypes ( MNCN 16.01/16558) collected 21°17'53"S 40°30'59"W, 30 m, 22 July 2009. Paratype 5 ( MZUSP 2715) collected 21°33'54"S 40°42'53"W, 23 m, 20 July 2009. Two paratypes ( MNCN 16.01/16559) collected 21°34'12"S 40°25'32"W, 28 m, 23 July 2009. Morphological data of selected specimens of the type series are provided in Table 2 .

Additional material examined. Streptodonta pterochaeta ( Southern, 1914) . Holland, Schouwen-Duiveland: 1 specimen ( ZMH P- 14715), coll. 30 April 1966, Wolff.

Description. Relatively medium-sized, fragile bodies, most specimens examined anterior fragments, with few chaetigers after proventricle segments; largest fragment paratype 1 (ZUEC-POL 316), 5.4 mm long, 0.4 mm wide, with 38 chaetigers ( Table 2 ); pigmentation patterns absent in preserved material, no live animals examined; body with dorsal tufts of cilia in transverse rows on each chaetiger ( Figs 16 A; 17C, E), dorsal to bases of dorsal cirri ( Fig. 17 C) and a tuft of cilia ventrally, close to bases of ventral cirri ( Figs 16 B, D; 17A). Palps foliaceous, triangular, wider than prostomium ( Figs 15 A; 16A–D). Prostomium ovate with 2 pairs of eyes in trapezoidal arrangement and 1 pair of anterior eyespots; lateral antennae inserted close to anterior margin, extending to about twice length of palps; median antenna inserted close to posterior border of prostomium, posterior to posterior pair of eyes, about twice as long as lateral antennae ( Figs 15 A; 16A, C). Nuchal organs as pair of dorso-lateral densely ciliated rows on posterior border of prostomium ( Fig. 16 A, C). Peristomium dorsally shorter than anterior chaetigers; dorsal peristomial cirri up to twice as long as median antenna but thinner, ventral peristomial cirri slightly shorter than lateral antennae ( Fig. 16 A–D). Dorsal cirri of chaetiger 1 longer than remaining appendages, thinner than dorsal peristomial cirri ( Figs 15 A; 16A); dorsal cirri of remaining chaetigers alternating thin cirri, about as long as dorsal peristomial cirri, and distally tapering cirri as wide as antennae, about as long as 3/4–1/2 body width at corresponding chaetiger ( Figs 15 A; 16A); ventral cirri shorter than parapodial lobes, ovate on anteriormost parapodia, leaf-like to pyriform from chaetigers 3–4 onwards ( Figs 16 B, D; 17A). Parapodial lobes stouter on anterior body, thinner from proventricle posteriorwards. Anterior parapodia with 2–10 spiniger-like chaetae each; midbody parapodia with 1–6 each; spiniger-like chaetae with slightly spinulated shafts subdistally; blades with short, thin spinulation, bidentate, teeth small, about same size or distal tooth slightly larger ( Figs 15 C; 17B); blades 67–25 µm long on anterior body, 62–32 µm long on midbody, ~45 µm long on posterior body ( Table 2 ). Anterior body parapodia with more than 30 falcigers each, midbody parapodia with 10–15 falcigers each; falcigers with subdistally spinulated shafts; on anterior chaetigers, blades 15–10 µm long, with coarse, short spinulation and bidentate teeth of similar size, obliquely directed ( Figs 15 D; 17D; Table 2 ); from midbody Streptodonta fauchaldi sp. n. Holotype Paratype 1 Paratype 2 Paratype 3 Paratype 4 Paratype 5 onwards, blades slightly shorter, 15–10 µm long, spinulation shorter or absent, and bidentate, distal tooth conspicuously shorter than subdistal one ( Figs 15 E; 17F–G; Table 2 ). Dorsal simple chaetae only present from mid- to posterior body chaetigers ( Table 2 ), thinner than remaining chaetae, subtly sigmoid, subdistally spinulated, and bidentate with small teeth, subdistal tooth slightly larger than distal one, with rounded space between teeth ( Fig. 15 F); ventral simple chaetae only present from mid- to posterior body chaetigers ( Table 2 ), approximately same width as falciger shafts, and bidentate, distal tooth conspicuously smaller than subdistal one ( Fig. 15 G). Anterior parapodia with up to 5 aciculae each, progressively diminishing towards posterior body, single acicula per parapodium from last proventricular segments; aciculae distally enlarged, apparently hollow, tips protruding from parapodial lobes ( Figs 15 B, 17C–D, 18A–C); aciculae on anterior body much stouter than falciger shafts ( Fig. 15 B), about twice as wide as falciger shafts, from midbody onwards. Pharynx long, extending through about 21 segments ( Fig. 15 A; Table 2 ), with small, conical tooth on anterior half and opening surrounded by 10 soft papillae and fringe of cilia ( Fig. 16 B, D); proventricle wider than pharynx, extending through 10–11 segments, with ~35 rows of muscle cells ( Fig. 15 A; Table 2 ).

Biology. Some animals found inside mucuous, transparent tubes, similar to those made by specimens of Exogone Ørsted, 1845 .

Remarks. Streptodonta fauchaldi sp. n. closely resembles S. exsulis , both species differing from S. pterochaeta in having spiniger-like chaetae. Streptodonta fauchaldi sp. n. differs from S. exsulis in having cilia distributed in transverse rows dorsally on chaetigers and in tufts at bases of dorsal and ventral cirri restricted to dorso-lateral areas (close to dorsal cirri in S. exsulis ), anterior body falcigers with teeth of similar size (distal tooth smaller than subdistal one throughout in S. exsulis ), blades of spiniger-like chaetae up to 67 µm long (up to 56 µm long in S. exsulis ), and proventricle extending through up to 13 chaetigers, with 37 rows of muscle cells (9 chaetigers with 29 rows of muscle cells in S. exsulis ) ( Ramos et al. 2010).

Etymology. The species is dedicated to Dr. Kristian Fauchald, an inspiration for many polychaetologists and marine biologists in general.

Figures

FIGURE 15. Streptodonta fauchaldi sp. n., holotype. (A) anterior body, dorsal view; (B) anterior parapodium, dorsal view; (C) spiniger-like chaeta, anterior body; (D) falcigers, anterior body; (E) falcigers, mid- to posterior body; (F) dorsal simple chaeta; (G) ventral simple chaeta. Scale bars: A, 500 µm; B, 30 µm; C – G, 10 µm.

FIGURE 16. Streptodonta fauchaldi sp. n., SEM. (A) anterior body, dorsal view; (B) anterior body, ventral view; (C) prostomium and peristomium, dorsal view; (D) anterior end, fronto-ventral view. Scale bars: A – B, 200 µm; C, D, 50 µm.

FIGURE 17. Streptodonta fauchaldi sp. n., SEM. (A) mid- to posterior body, ventral view; (B) detail, anterior parapodia, ventral view; (C) anterior to midbody parapodia, dorsal view; (D) detail, anterior to midbody parapodia, dorsal view; (E) tufts of cilia, dorsal view; (F) falcigers, midbody; (G) falcigers, mid- to posterior body. Scale bars: A, 100 µm; B, 20 µm; C, 50 µm; D – E, 10 µm; F – G, 5 µm.

FIGURE 18. Streptodonta fauchaldi sp. n., SEM. (A) detail of parapodium showing protruding tips of aciculae, midbody; (B), (C) detail, protruding tips of aciculae, mid- to posterior body. Scale bars: A, 5 µm; B – C, 1 µm.

Tables

TABLE 2. Morphological variation among selected specimens of the type series of Streptodonta fauchaldi sp. n.

MZUSP 2714	ZUEC-Pol 316	MZUSP 2716	MZUSP 2717	ZUEC-Pol 317	MZUSP 2715
Number of chaetigers 31 (inc.)	38 (inc.)	29 (inc.)	31 (inc.)	32 (inc.)	32 (inc.)
Total length x width at proventricle (mm) 3.2 x 0.42	5.40 x 0.40	2.65 x 0.40	2.65 x 0.36	2.40 x 0.45	2.75 x 0.25
Length of blades of pseudospinigers (μm) / number of pseudospinigers per parapodium
Anterior body 67–30 / 6–10	60–40 / 6–10	50–30 / 4–7	41–25 / 3–5	52–42 / 3–5	37–30 / 2–5
Midbody 62–47 / 4–6	49–45 / 3–6	55–37 / 2–5	50–37 / 2–4	50–42 / 1–3	42–32 /1–3
Posterior body --	~45 / 1–2	--	---	---
Length of blades of falcigers (μm) / number of falcigers per parapodium
Anterior body 15–10 / 30+	14–13 / 30 +	15–10 / 30+	15–11 / 30+	15–11 / 30+	12-11 / 30+
Midbody 15–12 / ~15	12–10 /10–15	15–12 / ~15	15–11 / ~10	12–8 / 7–10	12-8 / 5–6
Posterior body ---	~10 / ~7	---	---
Dorsal simple chaetae / ventral simple chaetae starting from --- (chaetiger)	---	---	---	---	32 / 32
Length of pharynx (chaetigers) 21	20	16 (evert.)	18 (evert.)	18 (evert.)	17 (evert.)
Length of proventricle (chaetigers); number of rows of muscle 10–11; 35	10; 35	10–11; 37	11; 33	13; 34	9; 36