New Prionospio and Laubieriellus (Annelida: Spionidae) species from Southeastern Brazil
Author
Peixoto, Antônio João Malafaia
Author
Paiva, Paulo Cesar De
text
Zootaxa
2019
2019-04-08
4577
3
529
547
journal article
27351
10.11646/zootaxa.4577.3.7
d816eb1e-43e3-4440-8f0f-4121aa0909bd
1175-5326
2632391
386738F0-FBAD-44FC-B9B4-ABDD992BB4AB
Prionospio nonatoi
sp. nov.
(
Figures 6–9
)
Type material
.
Brazil
.
Espírito Santo
Basin.
Holotype
:
Amb
7 D4,
19° 45' 54.56" S
39° 30' 25.23" W
, 12/2011 to 02/
2012, 144m
,
MZUSP 3387
.
Paratypes
: Amb7 B4R1,
20° 35' 25.16" S
39° 54' 58.31" W
, 12/2011 to 02/
2012, 157m
,
MNRJP 1828
(3 ind),
MZUSP 3388
(2 ind),
MZUSP 3389
(2 ind)
.
Additional material
: Amb7 B4,
20° 35' 25.16" S
39° 54' 58.31" W
,
157m
(47 ind); Amb7 D4,
19° 45' 54.56" S
39° 30' 25.23" W
,
144m
(15 ind); Amb7 E4,
19° 36' 4.32" S
39° 10' 34.07" W
,
147m
(6 ind).
Diagnostic feature
: Branchiae absent.
Description
: A small-sized spionid, largest individual about
4.8 mm
long,
0.18 mm
wide for 65 chaetigers,
holotype
4.6 mm
long,
0.18 mm
wide for 62 chaetigers. Body cylindrical, slightly dorsoventrally compressed throughout body, tapered towards the pygidium (
Fig. 6
A–D; 8A). Color in alcohol white. Pigmentation absent.
Prostomium narrow, slightly widened towards the anterior margin, rounded anteriorly, extending posteriorly as a narrow keel to the posterior margin of chaetiger 1 (
Figs 6
A–D; 7A; 8A–B). Eyes absent. Prostomial peaks not observed. Prostomium and peristomium well-delimitated by a deep incision (
Figs 6
A–D; 8A–B). Peristomium short, surrounding prostomium and partially fused to chaetiger 1, lacking lateral wings. Palps lost in all individuals.
Chaetiger 1 with few and short chaetae on both rami. Postchaetal lamellae auricular, reduced. Prechaetal lamellae absent.
Notopodial postchaetal lamellae foliaceous on chaetigers 2–5, largest on chaetiger 3 (
Figs 6
A–D; 7A; 8A–B) and smaller on chaetigers 4 and 5. Lamellae rounded from chaetiger 6 to chaetiger 11–14 and reduced to a low flap afterwards. Notopodial prechaetal lamella absent throughout. Dorsal crests low, from chaetiger 8 to chaetiger 10– 15 (
Fig. 8A
).
Neuropodial postchaetal lamellae of chaetiger 2 well-developed, triangular and elongated ventrally, triangular and not elongated ventrally on chaetiger 3, rounded on chaetigers 4–11 and reduced to a low flap afterwards (
Fig. 6D
;
8A
). Neuropodial prechaetal lamellae absent throughout.
Chaetae organized in two rows of sparsely granulated non-limbate capillaries (
Fig. 9A
). Towards the posterior region, capillaries progressively become elongate, thinner and less numerous (
Fig. 9B
).
Hooks in notopodia from chaetigers 32–44, up to three per fascicle, accompanied by 1–4 short, non-limbate capillaries. Hooks in neuropodia from chaetigers 11–12, up to seven per fascicle, accompanied by 1–4 non-limbate capillaries. Hooks multidentate, with 8 secondary teeth arranged in two rows above the main tooth (appearing as a single row of 4 secondary teeth in light microscopy) (
Figs 7
A–B; 9D). Small secondary hood present (
Fig. 9D
). Hooks accompanied by 3–10 short non-limbate capillaries.
Non-limbate and sparsely granulated sabre chaetae consistently from chaetiger 10 (
Fig. 9C
).
FIGURE 6.
Prionospio nonatoi
sp. nov.
(MNRJP 1828, paratypes). A. Anterior chaetigers, dorsal view. B. Anterior chaetigers and mid-body, dorsal view. C. Anterior chaetigers and mid-body stained with Shirlastain A, dorsal view. D. Anterior chaetigers and mid-body stained with Shirlastain A, dorso-lateral view. E. Pygidium, dorsal view. Abbreviations: nol, notopodial lamella; pe, peristomium; pr, prostomium.
FIGURE 7.
SEM of
Prionospio nonatoi
sp. nov.
A. Anterior chaetigers, dorsal view. B. Hooded hooks, dorso-lateral view. C. Hooks (hoods removed), lateral view. D. Pygidium, lateral view. Abbreviations: hh, hooded hooks; py, pygidium.
Branchiae absent in all individuals (
Figs 6
A–D; 7A; 8A–B). Pygidium with a pair of short rounded ventral cirri and a slightly longer mid-dorsal cirrus (
Figs 6E
;
7D
).
Oocytes from chaetigers 10–11, measuring up to 80 µm.
Methyl green pattern
: Intense staining on prostomium and peristomium.
Remarks
: According to
Radashevsky (2012)
, the late development of branchiae on anterior chaetigers is common in
Prionospio
, which could lead to the assumption that the species represents a juvenile stage. However, the complete absence of branchiae was observed in all 76 individuals, regardless of size (from
2.5 to 4.8 mm
long; from 39 to 65 chaetigers) or sexual maturity.
Owing to the lack of branchiae, the placement of this species in any current genus is problematic, since branchial morphology and distribution are characters of great significance for spionid taxonomy (
Foster 1969
,
1971
;
Blake & Kudenov 1978
;
Johnson 1984
;
Maciolek 1985
;
Blake 1996
;
Bick 2005
;
Delgado-Blas 2009
;
Radashevsky 2012
;
Blake
et al
. 2017
). For the
Prionospio
-complex, lack of branchiae is unusual, shared only with
Aurospio abranchiata
Neal, Paterson & Soto in
Paterson
et al
., 2016
, although its placement in
Aurospio
is questioned by
Blake
et al
. (2017)
, stating that, recently, several
Prionospio
species have been erroneously attributed to
Aurospio
.
FIGURE 8.
Prionospio nonatoi
sp. nov.
, dorsal view. A. Anterior segments and mid-body. B. Anterior segments. Abbreviations: dc, dorsal crest; nol, notopodial lamella; pe, peristomium; pr, prostomium.
FIGURE 9.
Prionospio nonatoi
sp. nov.
A. Anterior capillary chaeta. B. Posterior capillary chaeta. C. Sabre chaetae. D. Hooded hooks (as seen in light microscopy).
Among Brazilian species,
Prionospio nonatoi
sp. nov.
is similar to
P
.
cirrifera
,
P
.
delta
Hartman, 1965
,
P
.
fauchaldi
Maciolek, 1985
and
P
.
multibranchiata
in having only low dorsal crests and significant overlapping in starting chaetiger of notopodial and neuropodial hooded hooks. However, not only do these species possess branchiae, but
P
.
cirrifera
,
P
.
delta
, and
P
.
multibranchiata
present multiple pairs of smooth apinnate branchiae, while
P
.
fauchaldi
presents distinctly wrinkled branchiae on chaetigers 2–5. Even if branchiae are completely lost in these species, they can still be separated from
P
.
nonatoi
sp. nov.
by prostomial shape.
As for
Aurospio abranchiata
, both species are similar in having an enlarged notopodial postchaetal lamellae on chaetiger 3, distribution of dorsal crests, lack of branchiae, starting chaetiger of sabre chaetae and hooded hooks and presence of a secondary hood on the hooks. However, they can be separated based on the shape of notopodial postchaetal lamellae from chaetigers 2–5, the shape of neuropodial postchaetal lamellae from chaetigers 2–4 and by bathymetrical distribution.
Etymology
: The species name,
nonatoi
, is a tribute to Edmundo Ferraz Nonato (
1920–2014
), who dedicated his life to the study of marine worms and is considered the “father” of Brazilian polychaetology.
Habitat
: Fine sand to muddy sand, at
144–153 m
depth.
Distribution
: Southeast
Brazil
(Espírito Santos and Campos Basins), and only found during the summer.