Pseudostreblosoma brevitentaculatum, Nogueira, João Miguel De Matos & Alves, Tarsila Montrezoro, 2006

Nogueira, João Miguel De Matos & Alves, Tarsila Montrezoro, 2006, Two new terebellid polychaetes (Polychaeta: Terebellidae) from the state of São Paulo, southeastern Brazil, Zootaxa 1205, pp. 31-54 : 35-41

publication ID	https://doi.org/ 10.5281/zenodo.172367
DOI	https://doi.org/10.5281/zenodo.6261653
persistent identifier	https://treatment.plazi.org/id/546D1F41-FF8D-FFEA-1D40-FE1EFCDEFADC
treatment provided by	Plazi
scientific name	Pseudostreblosoma brevitentaculatum
status	sp. nov.

Treatment

Pseudostreblosoma brevitentaculatum View in CoL sp. nov.

( Figs. 1–4 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 )

Pseudostreblosoma View in CoL sp. A – Blankensteyn 1988: 78 –81, Fig. 19.

Material examined

State of São Paulo. Ubatuba, subtidally, in fine sand: 23º30’S, 45º04’W: 3 spec., coll. 21/03/2002, 9.3 m; 23º32’S, 44º43’W: 3 spec., coll. 17/03/2001, 45 m; 23º32’S, 44º45’W: 1 spec., coll. 15/11/2001, 44 m; 23º33’S, 45º08’W: 1 spec., coll. 14/04/2002, 13.1 m; 23º39’S, 45º18’W: 3 spec., coll. 23/05/2002, 15.4 m; 23º41’S, 44º17’W: 10 spec., coll. 23/ 05/2002, 16.7 m; 23º42’S, 45º12’W: 2 spec., coll. 20/05/2002, 21.3 m; 23º48’S, 45º10’W: 2 spec., coll. 20/05/2002, 30.1 m; São Sebastião, subtidally, in fine sand: 23º41’S, 45º16’W: 4 spec., coll. 13/02/2001, 15.4 m; 23º55’S, 45º13’W: 1 spec., coll. 27/06/2002, 27.5 m.

Comparative material examined

Pseudostreblosoma serratum : Australia, New South Wales, Sydney, Botany Bay: holotype (AM W18949) and spec. AM W195617.

Streblosoma acymatum : Australia, New South Wales, Sydney, Port Jackson: holotype (AM W 8), three paratypes (AM W5766, 5107, 5108) and spec. AM W22478.

Type series

Nine specimens, all of them incomplete, well preserved in 70 % ethanol. Holotype and paratypes 1–2 deposited at the MZUSP (holotype: MZUSP 16925; paratypes: MZUSP 16926), paratypes 3–5 deposited at the AM (AM W29695–29697, respectively), paratypes 6–8 deposited at the ZMUC ( ZMUC – POL – 1816). Holotype: coll. Ubatuba (23º41’S, 45º17’W), 23/05/2002, with 28 segments, 35 mm long, 2 mm wide, branchial filaments from the left side of the body removed. Paratype 1: coll. São Sebastião (23º55’S, 45º13’W), 27/06/2002, with 40 segments, 10 mm long, 1 mm wide. Paratype 2: coll. Ubatuba (23º41’S, 45º17’W), 23/05/2002, with 23 segments, 35 mm long, 2 mm wide. Paratype 3: coll. Ubatuba (23º41’S, 45º17’W), 23/05/2002, with 23 segments, 25 mm long, 2 mm wide. Paratype 4: coll. Ubatuba (23º32’S, 44º43’W), 17/05/2001, with 23 segments, 14 mm long, 1.2 mm wide. Paratype 5: coll. Ubatuba (23º30’S, 45º04’W), 21/ 03/2002, with 28 segments, 9 mm long, 0.9 mm wide. Paratype 6: coll. Ubatuba (23º41’S, 45º17’W), 23/05/2002, with 27 segments, 32 mm long, 2.5 mm wide. Paratype 7: coll. Ubatuba (23º39’S, 45º18’W), 23/05/2002, with 31 segments, 15 mm long, 1.5 mm wide. Paratype 8: coll. Ubatuba (23º41’S, 45º17’W), 23/05/2002, with 20 segments, 12 mm long, 1 mm wide.

Description

Body long, all specimens posteriorly incomplete, with up to 40 segments and measuring about 35 mm in length, by 2 mm in width. Buccal tentacles few in number, up to 14, distally expanded, slightly spatulate, short, not reaching beyond segments 6–8 ( Figs. 1 View FIGURE 1 A–B, 2A–C). Prostomium expanded, at base of upper lip; distal part swollen ( Figs. 1 View FIGURE 1 A–B, 2A, D–E), basal part with eyespots in lateral clusters and forming thin row across prostomium, right above posterior prostomial border, with distinct medial gap ( Fig. 1 View FIGURE 1 A–B). Peristomium developed, continuing dorsally posterior to prostomium, Vshaped, with anterior border densely ciliated, probably corresponding to nuchal organs ( Figs. 1 View FIGURE 1 A–B, 2A, D–F, H). Upper lip short, hoodlike, densely ciliated; lower lip short, restricted to oral area and covered by ventral lobe of segment 1 ( Figs. 1 View FIGURE 1 A–B, 2B–C, G–H). Segment 1 dorsally indistinct, covered by peristomium ( Figs. 1 View FIGURE 1 B, 2A, D–E), ventrally developed, forming one large semicircular to Wshaped ventral lobe below mouth ( Figs. 1 View FIGURE 1 A, 2B–C, G–H). Segment 2 short, forming one pair of short and thickened ventrolateral lobes, shorter than length of segment. Segments 3 and 4 progressively longer, with anterior margins thickened and short lateral lobes, shorter than those on segment 2 ( Figs. 1 View FIGURE 1 A–B, 2A–D). Three pairs of branchiae, each with numerous simple filaments progressively tapering to tips, originating from glandular area differentiated from remainder of dorsal integument ( Figs. 1 View FIGURE 1 A–B, 2A, D–E). Branchiae arranged in oblique to arched areas across segments 2–4, each with 2–3 rows of filaments; on segment 2, branchial filaments originating from large oblique areas, anteriorly starting at level of notopodia and extending dorsally and posteriorly until near posterior border of segment 2; on segment 3, branchial filaments originating from smaller areas, but with same arrangement as on segment 2, except for all branchial filaments being dorsal to notopodia; on segment 4, branchial filaments originating from arched areas around notopodia, at posterior half of segment ( Figs. 1 View FIGURE 1 A–B, 2A, D–E). Ventral surface of anterior segments glandular and somewhat corrugated on segments 2–12, followed by midventral stripe extending to posterior body, segments 2–3 midventrally fused in some specimens ( Fig. 2 View FIGURE 2 C, G–H). Notopodia starting from segment 2 ( Figs. 1 View FIGURE 1 A–B, 2B, D–E, G) and extending for 23–27 segments; notopodia elongate, rectangular and bilobed ( Figs. 2 View FIGURE 2 A–D, 3A). On segments 2–12, notopodia with smooth, slightly geniculate notochaetae, with narrow limbation, arranged in two rows of different sizes ( Fig. 3 View FIGURE 3 A–D). From segment 13, chaetae on anterior row of notochaetae as serrated and alimbate chaetae, with long and thin blades, and chaetae on posterior row of notochaetae as smooth and geniculate capillaries, with narrow limbation ( Figs. 1 View FIGURE 1 E–F, 3E –H). Neuropodia starting from segment 5, sessile on anterior thorax ( Figs. 1 View FIGURE 1 A, 2B), then progressively more elevated from surface of body ( Fig. 4 View FIGURE 4 A), forming raised neuropodial pinnules on abdomen. Neuropodia with thin shafts throughout, attached by ligaments to uncini. Uncini high and elongate, with short triangular heel, rounded base and short prow, dorsal button well developed, far from anterior margin of uncini, main fang surmounted by 3–4 rows of secondary teeth ( Figs. 1 View FIGURE 1 C–D, 4A–F).

Remarks

Pseudostreblosoma brevitentaculatum sp. nov. was described for the first time in an unpublished MSc. thesis ( Blankensteyn 1988), as Pseudostreblosoma sp. A. We did not examine the material studied by Blankensteyn, but his description, except for some details, is very complete and leaves no doubt it is the same species that we describe here.

Pseudostreblosoma brevitentaculatum sp. nov. agrees with the generic description in having notopodia from segment 2, neuropodia from segment 5 and notochaetae as limbate capillaries and serrated chaetae. According to Hutchings and Glasby (1987), all limbate chaetae are denticulated under high magnification, but we distinguish limbate from serrated chaetae by the former being completely denticulated, with numerous distally rounded small teeth ( Fig. 3 View FIGURE 3 B–D, F–H), while the latter have distinct serrated blades, each with one lateral row of larger and sharp teeth ( Fig. 3 View FIGURE 3 F). Distally, limbate chaetae usually have a lateral row of larger teeth, but they are closer to each other than on serrated chaetae and distally blunt ( Figs. 3 View FIGURE 3 C–D, G–H).

In this study, nephridial papillae were not seen on anterior segments. Papillaelike structures, with whitish tissue, different from the adjacent integument, are present on segments 2–10, ventral to the notopodia or between the notopodia and the neuropodia ( Fig. 3 View FIGURE 3 A). However, the surface of the anterior segments is so irregular that it is difficult to determine if these structures are true nephridial papillae or not. So, as we did not dissect any specimen to clarify the position of nephridia, we consider this feature as doubtful.

Our new species is distinguished from P. serratum and P. longum by having tentacles which are distally expanded and much shorter than occur in these species, the dorsally Vshaped peristomium, the presence of lobes on anterior segments, by the longitudinal arrangement of branchial filaments, in arcs or oblique rows, and by the presence of glandular tissue from which branchial filaments originate.

In addition, P. longum is a much larger species, measuring up to 200 mm and with notopodia continuing until near the posterior end, and according to the original description, this would indicate that more than 100 pairs of notopodia are present ( Mohammed 1973). Pseudostreblosoma serratum also has more pairs of notopodia than P. brevitentaculatum sp. nov., as one complete specimen studied by Hutchings and Glasby (1987) had 45 pairs of notopodia.

On the other hand, the presence of corrugated glandular surfaces on the anterior ventrum of P. brevitentaculatum sp. nov. and branchial filaments originating from glandular tissues, are features also present in Streblosoma acymatum Hutchings and Rainer, 1979 , a species from which P. brevitentaculatum sp. nov. is distinguished by the former taxon lacking lobes on anterior segments and having only smooth, limbate notochaetae, as is characteristic of Streblosoma .