Bryozoan framework composition in the oddly shaped reefs from Abrolhos Bank, Brazil, southwestern Atlantic: taxonomy and ecology
Author
Ramalho, Laís V.
Author
Taylor, Paul D.
Author
Moraes, Fernando Coreixas
Author
Moura, Rodrigo
Author
Amado-Filho, Gilberto M.
Author
Bastos, Alex C.
text
Zootaxa
2018
2018-09-20
4483
1
155
186
journal article
29515
10.11646/zootaxa.4483.1.6
b9453839-5f43-4081-a642-f7bb30caf894
1175-5326
1437570
05A08470-9473-4147-B54B-AB0C90173572
Stylopoma hastata
n. sp.
(
Fig. 5C–E
)
Stylopoma
sp. 2:
Reis
et al
., 2016
: supplementary table;
Bastos
et al
., 2018
: table 1.
Material
examined.
Abrolhos Bank
,
Bahia
State,
Brazil
:
Holotype
: MNRJ-Bry1357,
Parcel dos Abrolhos
,
4 m
depth,
February 2014
, col.
R. Moura
, G.
Amado-Filho
& A
.
Bastos
;
Paratype
: MNRJ-Bry1367,
Parcel dos Abrolhos
,
15 m
depth,
February 2014
, col.
R. Moura
, G.
Amado-Filho
& A.
Bastos.
Etymology.
From the Latin '
hastatus, -a, -um
', meaning 'spear-shaped, armed with a spear', used in reference to the shape of one of the interzooidal avicularia.
Diagnosis.
Stylopoma
with almost circular orifice with U-shaped sinus and small, ball-shaped condyles; single or paired small triangular lateral oral avicularia; two
types
of large interzooidal avicularia: spear-shaped, usually positioned parallel to autozooids; and elongated, directed transversely to the growth axis of the colony.
Description.
Encrusting colonies, multilamellar (
Fig. 5C
). Autozooids rectangular, longer than wide (410– 508–580 µm long x 259–345–428 µm wide); frontal wall perforated by numerous small circular pores (54–67) inserted in depressions, slightly convex; circular to elongate areolar pores around the perimeter (
Fig. 5C
). Orifice wider than long (77–86–94 µm long
x 99
–107–116 µm wide), displaced from the median axis of the zooid, with a thick and crenulate region without pores around the orifice, distal border smooth, proximal border with U-shaped sinus, and a pair of small ball-shaped condyles at the corners (
Fig. 5D
). Single or, rarely, a pair of small lateral oral avicularia (60–71–83 µm long), located proximally near the sinus or laterally to orifice, never terminally distal, directed distally and slightly laterally; rostrum triangular, almost equilateral, raised distally from the frontal shield, crossbar complete. Oral avicularium may be absent (
Fig. 5C, D
). Two different
types
of large vicarious avicularia (
Fig. 5C, E
): (1) avicularia oriented parallel to the autozooids or slightly inclined, directed distally, rostrum elongate (425–450–481 µm long), tip pointed or slightly rounded (lanceolate), crossbar complete (sometimes broken) (
Fig. 5C
); (2) avicularia oriented transversely to the autozooids on a salient chamber, larger than previous
type
(562–617–739 µm long), covering two or three autozooids, rostrum elongated and curved, tip rounded, crossbar complete (
Fig. 5C, E
). Ovicells not observed.
Geographic distribution.
Abrolhos Bank, Bahia State, Brazil (
Reis
et al
. 2016
;
Bastos
et al
. 2018
; present study) and Espírito Santo State, Brazil (18°40’S, 38°28’W - MNRJ-Bry398,
7 May 1974
).
Remarks.
The presence of two
types
of large interzooidal avicularia (lanceolate and elongate), plus a small triangular lateral oral avicularium and a circular orifice with U-shaped sinus and small ball-shape condyles, differentiates the new species from almost all other species of
Stylopoma
. The Abrolhos specimens are similar to
Stylopoma
s
pongites
(
Pallas, 1766
) in having two
types
of large vicarious avicularia, but the avicularia differ in shape, one
type
having a spatulate rostrum and the other, larger avicularium on a raised cystid with a long and parallel-sided rostrum, terminally pointed and laterally directed, the orifice is as long as wide, the anter has a sparsely denticulate inner rim and the poster a slit-like deep sinus, condyles are smooth, deep and wide with distinct processes pointing medially. Two other species recorded from
Brazil
have small condyles in the orifice –
S. aurantiacum
Canu & Bassler, 1928a
and
S. carioca
Winston
et al
., 2014
– but in both species the umbo is raised at the centre of the zooid; the first species has no vicarious avicularia, and the second has an orifice longer than wide, and vicarious avicularia with spatulate mandibles.