Two new terebellid polychaetes (Polychaeta: Terebellidae) from the state of São Paulo, southeastern Brazil
Author
Nogueira, João Miguel De Matos
Author
Alves, Tarsila Montrezoro
text
Zootaxa
2006
1205
31
54
journal article
50788
10.5281/zenodo.172367
a5a4ca05-c6a0-4c26-8b95-552c1f52415a
11755326
172367
Pseudostreblosoma brevitentaculatum
sp. nov.
(
Figs. 1–4
)
Pseudostreblosoma
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.
FIGURE 1.
Pseudostreblosoma brevitentaculatum
sp. nov
.. A: paratype 1 (MZUSP 16926), lateral view; B: holotype (MZUSP 16925), anterior end, dorsal view; C: uncinus, segment 6; D: abdominal uncinus; E: long notochaeta, segment 13; F: short notochaetae, segment 13. Scale bars: A–B: 1 mm; C–D: 0,0 25 mm; E–F: 0,0 5 mm.
FIGURE 2.
Pseudostreblosoma brevitentaculatum
sp. nov.
A: anterior end, dorsal view; B: anterior end, ventrolateral view; C: anterior end, ventral view; D: dorsal view of anterior segments of left side of body, showing the origin of branchial filaments, after they were cut off; E: closer dorsal view of prostomium, peristomium and segment 2; F: detail of border between basal part of prostomium and peristomium, showing conspicuous ciliation in latter; G: oral area, superior view; H: ventrolateral view of anterior end, higher magnification; arrow points to origin of segment 1, between peristomium and segment 2. ll = lower lip; P = prostomium; P (bp) = basal part of prostomium; P (dp) = distal part of prostomium; Pe = peristomium; ul = upper lip; numbers refer to segments. Scale bars: A: 400 µm; B: 240 µm; C, G: 200 µm; D: 150 µm; E: 100 µm; F: 20 µm; H: 50 µm.
FIGURE 3.
Pseudostreblosoma brevitentaculatum
sp. nov
.. A: notopodia, segments 4–6; arrows point to papillae; B: notochaetae, segment 6; C: closer view of tip of short notochaetae and midlength of long notochaetae, segment 6; D: tip of long notochaetae, segment 6; E: posterior notochaetae; F: closer view of chaetae shown in figure E, showing blades of serrated (short) notochaetae and midlength region of limbate (long) notochaetae; G: subdistal area of limbate (long) notochaeta, same notopodium; H: tip of same chaeta. Scale bars: A: 100 µm; B: 5 µm; C, G: 2 µm; D: 6 µm; E: 40 µm; F, H: 4 µm.
FIGURE 4.
Pseudostreblosoma brevitentaculatum
sp. nov
.. A: posterior thoracic neuropodium; B: uncini, segment 5; C–F: posterior thoracic uncini; arrows point to dorsal buttons. Scale bars: A: 70 µm; B, C, F: 6 µm; D: 4 µm; E: 5 µm.
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
A–B, 2A–C). Prostomium expanded, at base of upper lip; distal part swollen (
Figs. 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
A–B). Peristomium developed, continuing dorsally posterior to prostomium, Vshaped, with anterior border densely ciliated, probably corresponding to nuchal organs (
Figs. 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
A–B, 2B–C, G–H). Segment 1 dorsally indistinct, covered by peristomium (
Figs. 1
B, 2A, D–E), ventrally developed, forming one large semicircular to Wshaped ventral lobe below mouth (
Figs. 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
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
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
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
C, G–H). Notopodia starting from segment 2 (
Figs. 1
A–B, 2B, D–E, G) and extending for 23–27 segments; notopodia elongate, rectangular and bilobed (
Figs. 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
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
E–F, 3E –H). Neuropodia starting from segment 5, sessile on anterior thorax (
Figs. 1
A, 2B), then progressively more elevated from surface of body (
Fig. 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
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
B–D, F–H), while the latter have distinct serrated blades, each with one lateral row of larger and sharp teeth (
Fig. 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
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
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
.