Anguillosyllis palpata ( Hartman, 1967 )

Barroso, Rômulo, Paiva, Paulo Cesar De, Nogueira, João Miguel De Matos & Fukuda, Marcelo Veronesi, 2017, Deep sea Syllidae (Annelida, Phyllodocida) from Southwestern Atlantic, Zootaxa 4221 (4), pp. 401-430 : 422-424

Anguillosyllis palpata ( Hartman, 1967) , amended

Figure 12

Braniella palpata Hartman 1967: 55 , pl. 14.

Material examined. Project ‘Habitats ’. 21°11’6”S, 40°12’17”W, 807 m: 3 specs, 29 Jun 2008; 22°20’50”S, 40°2’58”W, 705 m: 8 specs, 8 Jul 2008; 22°25’54”S, 39°53’55”W, 1299 m: 3 specs (MZUSP 2939), 29 May 2008; 22°33’33”S, 40°26’40”W, 393 m: 1 spec., 11 Jul 2008; 22°52’14”S, 40°5’8”W, 2455 m: 2 specs (MZUSP 2938), 22 May 2008; 22°59’52”S, 40°47’45”W, 689 m: 8 specs (MZUSP 2940), 24 Jun 2008; 23°1’33”S, 40°45’22”W, 964 m: 3 specs (MZUSP 2944), 16 Jan 2009; 23°12’59”S, 40°57’35”W, 761 m: 1 spec. (MZUSP 2943), 29 Jan 2009; 23°13’2”S, 40°57’36”W, 724 m: 12 specs, 24 Jun 2008; 23°18’28”S, 40°24’52”W, 2513 m: 2 specs (MZUSP 2498), 16 Fev 2009; 23°3’33”S, 40°41’53”W, 1285 m: 2 specs (MZUSP 2946), 17 Jan 2009; 23°39’20”S, 41°18’28”W, 701 m: 1 spec., 28 Jan 2009; 23°41’7”S, 41°16’4”W, 1017 m: 1 spec., 12 Jan 2009; 23°45’8”S, 41°11’51”W, 1319 m: 3 specs (MZUSP 2942), 13 Jan 2009; 23°45’18”S, 39°59’57”W, 2423 m: 1 spec., 6 Fev 2009; 24°1’24”S, 40°54’13”W, 2493 m: 1 spec., 17 Feb 2009; 24°29’15”S, 40°23’22”W, 2981 m: 1 spec., 19 May 2008; 24°29’21”S, 40°23’20”W, 3028 m: 1 spec., 5 Fev 2009. Project ‘ AMBES ’. 19°3’10”S, 37°45’28”W, 2954 m: 3 specs, 23 Jun 2013; 19°3’30”S, 37°48’46”W, 1347 m: 8 specs (MZUSP 2960), 1 Jul 2013; 19°34’20”S, 38°41’19”W, 449 m: 1 spec., 30 Jun 2013; 19°47’2”S, 39°3’14”W, 1251 m: 6 specs (MZUSP 2959), 26 Jun 2013; 19°53’31”S, 39°32’56”W, 1023 m: 12 specs (MZUSP 2934), 13 Jan 2012; 19°54’4”S, 39°22’29”W, 1335 m: 8 specs (MZUSP 2958), 27 Jun 2013; 20°48’37”S, 38°45’28”W, 2494 m: 1 spec. (MZUSP 2953), 15 Jun 2013; 20°53’28”S, 38°21’21”W, 3000 m: 1 spec. (MZUSP 2955), 12 Jun 2013; 21°4’43”S, 40°4’12”W, 1295 m: 9 specs (MZUSP 2927), 9 Jun 2013.

Additional material examined. Braniella palpata — Argentina, Tierra del Fuego, Cape Horn, Drake Passage (56°06’29”S, 66°24’29”W, 384–494 m deep): 1 spec. ( USNM 55505 , holotype), coll. University of Southern California (Department of Zoology), ‘ Eltanin R /V ’, 18 Sep 1963, det. O. Hartman, 1967 ; Chile, Drake Passage (57°13’01”S, 70°57’W, 3770–3806 m deep): 1 spec. ( USNM 55506 , paratype), coll. University of Southern California (Department of Zoology), ‘ Eltanin R /V ’, 4 Nov 1962, det. O. Hartman, 1967 ; Antarctica, Weddell Sea (72°47’36”S, 30°29’42”W, 3697 m): 1 spec. ( USNM 46847 ), coll. University of Connecticut, ‘ Glacier II R/V ’, 14 Mar 1969, det. O. Hartman ; Antarctica, Coats Land (73°28’24”S, 30°26’24”W, 3111 m deep): 3 specs ( USNM 46846 ), coll. University of Connecticut, ‘ Glacier II R/V ’, 13 Mar 1969, det. O. Hartman .

Description. Usually of relatively small body size, complete specimens with 11 chaetigers, largest individual analysed 4.3 mm long, 0.5 mm wide. Palps elongate, distally acute, basally fused to 1/2–3/4 of their lengths ( Fig. 12 A–B, D–E). Prostomium ovate, conspicuously shorter than palps, wider than long ( Fig. 12 A, D); eyes absent, antennae ovate, broken or missing in most specimens, median antenna inserted approximately at middle of prostomium, lateral antennae inserted more anteriorly. Peristomium shorter than anterior chaetigers, frequently densely covered by cilia, with 1 pair of small, papilliform peristomial cirri. Dorsal cirri with short cirrophores and long, slender cirrostyles often coiled over dorsum, most cirri broken or missing; dorsal cirri absent on chaetiger 2. Ventral cirri papiliform to digitiform, progressively more pyriform towards posterior body, inserted at midlength of parapodial lobes, not reaching their tips ( Fig. 12 B, F). Parapodial lobes distally rounded to slightly bilobed, with posterior lobe more pronounced; dorsalmost chaetae emerging from tip of lobe, below semicircular flap located dorsally on distal half of parapodial lobe ( Fig. 12 F, H), chaetae progressively inserted more basally along lobe ventralwards, with numerous rows of chaetae, especially on anterior chaetigers ( Fig. 12 B, F, I). Anterior parapodia with 30+ compound chaetae each, posterior parapodia with ~10–15 chaetae each; chaetae heterogomph, with long, unidentate, finely spinulated to smooth blades (spinulation nearly inconspicuous under compound microscope); conspicuous dorso-ventral gradation in length, blades 320–30 µm, 450–30 µm and 350–20 µm long on anterior, mid- and posterior body chaetigers, respectively ( Fig. 12 C, G). Parapodia throughout usually with 2 aciculae each, aciculae away from each other at tip of parapodium, one usually extending anteriorly and other posteriorly to chaetae, in dorsal side of parapodium, frequently with tips protruding from parapodial lobes ( Fig. 12 H); aciculae subdistally slightly enlarged, distally acute. Pharynx through 2–3.5 chaetigers, border surrounded by ~10 soft, distally rounded papillae, tooth absent. Proventricle barrel- to heart-shaped, through ~3 chaetigers (0.2–0.7 mm long), with ca. 12 rows of muscle cells.

Remarks. In the original description, this species was illustrated as having dorsal cirri on chaetiger 2 ( Hartman 1967, Plate 14), although this was not mentioned in the description, and it was considered as such by Aguado & San Martín (2008). This, however, could not be confirmed in any of the specimens herein analysed, including the holotype and paratypes. Therefore, we amend the description of the species, to state that dorsal cirri are absent on chaetiger 2.

Anguillosyllis palpata differs from A. pupa as this latter species has completely or almost completely fused palps and proventricle with 20–25 rows of muscle cells, while in A. palpata the proventricle has 12 rows of muscle cells. Anguillosyllis palpata also differs from A. capensis , as this species has more rows of muscle cells in the proventricle (30 rows) and parapodial lobes with distinctly larger, elongate post-chaetal lobes (see Aguado & San Martín 2008, Fig. 1 ).

Geographic distribution and bathymetric range. South Atlantic Ocean—Argentina ( Cape Horn – type locality, 384–494 m deep); Brazil ( Campos and Espírito Santo basins, 393–3028 m deep) . South Pacific Ocean— Chile (3770–3806 m deep). Antarctic Ocean—Weddell Sea (3111–3697 m deep).

Figures

FIGURE 1. Exogone anomalochaeta. (A) anterior body, dorsal view; (B – C) falcigers, anterior and mid- to posterior body chaetigers, respectively; (D, H) aciculae, anterior and posterior body chaetigers, respectively; (E – F) dorsal simple chaetae, anterior and posterior body chaetigers, respectively; (G) ventral simple chaeta.

FIGURE 12. Anguillosyllis palpata, SEM. (A) entire worm, dorsal view; (B) anterior body, ventral view; (C) intermediate compound chaeta, chaetiger 8 (mid- to posterior body); (D – E) close ups of the anterior end, dorsal and ventral views, respectively; (F, I) anteriormost and posteriormost parapodia, respectively, left-hand side, dorsal view; (G) ventralmost compound chaeta, chaetiger 6 (midbody); (H) close up of the tip of parapodial lobe of chaetiger 3, dorsal view; (J) close up of the tips of compound chaetae, anterior body.