New species of Bryozoa from Madeira associated with rhodoliths
Author
Souto, Javier
Author
Reverter-Gil, Oscar
Author
Ostrovsky, Andrew N.
text
Zootaxa
2014
3795
2
135
151
journal article
45820
10.11646/zootaxa.3795.2.3
2f2585ce-e9e1-4c7a-a337-cf50fe3e3eec
1175-5326
228822
6DE4B4A5-9369-4F9A-9F1A-C61EC4528F3A
Schizomavella
sp.
(
Figs 22–25
;
Table 4
)
Material examined.
MNCN
–25.03/3865:
32º38’30.67’’N
16º49’47.49’’W
,
18 m
,
April 2011
, on rhodolith.
Description.
Colony encrusting, unilaminar, developing as an irregular subcircular crust. Autozooids in radial series, separated by fine, raised sutures; rectangular to polygonal, slightly convex. Frontal shield nodular, irregularly perforated by 6–12 large, rounded pseudopores and two lateral rows of marginal areolar pores. Suboral avicularium with a small pore on each side. Primary orifice circular, as long as wide; sinus large, U-shaped, occupying more than half of proximal border; condyles small, oval, smooth, reaching edges of sinus and difficult to see. Oral spines long, stout, 2–3, even 4, present only in early ontogeny. Orifice surrounded laterally and proximally by smooth, wide gymnocystal rim incorporating a medial suboral avicularium, occasionally slightly displaced laterally. Avicularia small, monomorphic, inclined at an angle on a small prominence. Rostrum elongate, oval-triangular, directed proximally. Palatal foramen large; crossbar complete, with very small columella. Small opesia of avicularium with raised triangular ‘hood’. Zooids with uniporous septula in vertical walls, placed in rows parallel to basal wall. Ovicells absent in colony examined. Ancestrula unknown.
TABLE 4.
Measurements (in mm) of
Schizomavella
sp.
| Mean |
SD |
Minimum |
Maximum |
N |
| Autozooid length |
0.436 |
0.0208 |
0.413 |
0.469 |
6 |
| Autozooid width |
0.373 |
0.0722 |
0.255 |
0.440 |
6 |
| Orifice length |
0.095 |
0.0121 |
0.073 |
0.104 |
6 |
| Orifice width |
0.100 |
0.0049 |
0.090 |
0.103 |
6 |
SD, Standard deviation; N, number of measurements.
Remarks.
Schizomavella
is a speciose genus with about 36 Recent species reported from all over the world. About ten species are present in the NE Atlantic, another six are supposedly distributed in the Atlanto- Mediterranean region, and other seven species are reportedly Mediterranean endemics.
None of them has an avicularian opesia with a raised triangular rim. Some species have a smooth gymnocystal rim surrounding the zooidal orifice and median suboral avicularium. Among them,
Schizomavella cristata
(
Hincks, 1879
)
and
S. subsolana
Hayward & McKinney, 2002
have a triangular suboral avicularium. In
S. fischeri
(
Jullien, 1882
)
the orifice has an arch of 5–7 stout articulated spines and the smooth frontal shield is perforated by a few small pseudopores. In
S. auriculata
(
Hassall, 1842
)
the orifice is characteristically drop-shaped and the condyles are sharply cusped. Two cryptic species,
S. sarniensis
Hayward & Thorpe, 1995
and
S. grandiporosa
Canu & Bassler, 1925
, recently discussed by
Souto
et al
. (2013)
, differ from
Schizomavella
sp. in not only lacking the elevated avicularian rim but in having a more quadrangular orifice, with the gymnocystal rim forming two marked ‘corners’ proximolaterally. They also have a shallower sinus, larger condyles (distally toothed in
S. sarniensis
) and a shorter avicularium. In these two latter species the frontal shield becomes prickly in later ontogeny, with the large pseudopores deeply immersed, a character that cannot be seen in our single colony of
Schizomavella
sp.
As
we have a single colony of
Schizomavella
sp., we cannot study possible variations like changes of the frontal shield with increasing calcification, or the polymorphism of avicularia, if existing; even more, ovicells are lacking. We therefore refrain from giving a specific attribution at present.
In spite of this, we believe that the characters available allow differentiating our colony from the rest of the known species of
Schizomavella
in the Atlantic-Mediterranean region. Only three species of this genus were previously reported from Madeira—
Schizomavella discoidea
(
Busk, 1859b
)
,
S. auriculata
and
S. noronhai
(
Norman, 1909
)
(see
Busk 1859b
;
Hincks 1880
;
Norman 1909
;
Berning 2012
). Furthermore,
Norman (1909)
indicated that some specimens of
S. auriculata
belonged to
var.
ochracea
, which is now considered a separate species, placed in the genus
Stephanotheca
(
Reverter-Gil
et al
. 2012
)
. All of these species clearly differ from
Schizomavella
sp. However, taking into account the misunderstandings surrounding the identity of
S. auriculata
until its redescription by
Hayward & Thorpe (1995)
, it is likely that some previous records of this species from Madeira actually correspond to
Schizomavella
sp.