Notoplites saojorgensis, Berning, 2013

Berning, Björn, 2013, New and little-known Cheilostomata (Bryozoa, Gymnolaemata) from the NE Atlantic, European Journal of Taxonomy 44, pp. 1-25 : 2-5

Notoplites saojorgensis sp. nov.

urn:lsid:zoobank.org:act:19A50609-B149-46AC-9A17-237D31A95867

Fig. 1 , Table 1

Notoplites marsupiatus ( Jullien, 1883) – Calvet 1931: 69.

Non Scrupocellaria marsupiata – d’Hondt 1975: 556, figs 14-16 (part or whole).

Differential diagnosis

There are only two other NE Atlantic Notoplites species that have a marginally fimbriated scutum covering the entire opesia: N. clausus (Busk, 1884) and N. marsupiatus ( Jullien, 1883) . N. saojorgensis sp. nov. differs from these in generally lacking distal orificial spines, in having wider zooecia and larger scuta, and in having ooecia with a triangular proximomedian fenestra. Moreover, in comparison with N. marsupiatus , zooids in the new species are much larger, the ooecia are distinctly shorter, and the orifice is wider than long. Additional differences to N. clausus are that the internodes are more robust, that the lateral avicularium is clearly visible in frontal view, and that there are more and longer fissures between marginal branches in the scutum.

Etymology

The species is named after its type location, São Jorge Island (Azores archipelago).

Type Material

Holotype

MNHN 4163 , a large free colony, Princess Alice Stn 1349, 1250 m, 19 Aug. 1902, 38°35’30’’ N – 28°05’45’’ W (Azores, off south-central São Jorge Island ), on sandy mud of volcanic origin.

Paratypes

Same locality information as holotype: MOM 42 0877, numerous detached internodes; MOM 42 1213, several internodes embedded in Canada balsam on a glass slide.

Description

Colony erect, jointed, dichotomously branching, forming a delicate tuft of up to 6.5 cm in height, attached by numerous rhizoids that form a supporting stalk; zoarium porcelain white in dried state ( Fig. 1 A-C). Branches formed by two series of alternating autozooids, mostly with 4-9 autozooids between bifurcations, zooids opening on one side only ( Fig. 1D ). Branching points composed of a single proximomedian zooid and two distolateral ones, with the nodes developing immediately distal to the latter zooids by breakage of the narrow proximal parts of the subsequent zooids ( Fig. 1E ). Autozooids very elongate, narrowest and tubular proximally, widening distally with the distal half of zooids turned outwards at an angle of c. 40°, usually (much) less than half of total autozooid length occupied by the scutum/membranous area and orifice ( Fig. 1 E-F); skeletal surface smooth, convex, zooids separated by a distinct groove, forming a zigzag line on the abfrontal side ( Fig. 1D ). Rhizoids produced from a small pore near proximal end on the abfrontal side of some zooids, closely approximated to form a single stalk ( Fig. 1 C-D).

Orifice slightly raised and displaced towards the outer zooid margin ( Fig. 1E ), very well-defined, wider than long and widest in distal third, straight proximal margin formed by distal scutum, operculum thickly sclerotised ( Fig. 1F ). Scutum convex, about as wide as long, distally branched with the branch ends merging with the circum-opesial gymnocyst and covering the membranous area like a well-fitting lid, branches separated by some 14-20 narrow fissures of variable length, some reaching almost half of scutum length ( Fig. 1F ); scutum originating from a broad inconspicuous base near the inner distal zooid margin just proximolateral to orifice, with the scutum base occasionally bearing a single greatly enlarged spine ( Fig. 1E ); a smaller single spine distal to orifice only in median zooids at branching points ( Fig. 1E ).

Two adventitious avicularia of about the same size and shape per zooid ( Fig. 1F ): one situated lateral to orifice and forming the outer zooid margin, with the triangular rostrum directed outwards and the frontal area more or less distally; the other one situated on a raised cystid just proximally to scutum, with the distally slightly downcurved rostrum directed proximally; mandibles in both avicularia hinged on inconspicuous condyles formed by the distal part of an immersed cryptocystal shelf in the proximal area.

Ovicell globular, prominent, the inner half of ooecium resting on the proximal part of the distal zooid, slightly longer than wide, surface somewhat uneven and with a proximomedian elongate-triangular fenestra pointing distally, the proximolateral ooecial margins reaching towards mid-distance of lateral orifice rim, ovicell opening well arched above orifice ( Fig. 1G ).

An ancestrula was not observed.

Remarks

There are two species that are closely related to Notoplites saojorgensis sp. nov., the types of both of which have recently been figured and described by Souto et al. (2011): N. marsupiatus ( Jullien, 1883) , originally recorded from the continental slope of NW Spain, and N. clausus (Busk, 1884) , sampled some 400 km west of the Azores. All three species share the same type of fimbriated scutum.

Notoplites clausus was later considered to be a junior synonym of N. marsupiatus by Jullien (1888), Calvet (1907) and other workers. However, Souto et al. (2011) showed that they are distinct species and reinstated N. clausus . In turn, Notoplites saojorgensis sp. nov., which was identified as N. marsupiatus by Calvet (1931), is clearly different from these two. The specimens imaged as Scrupocellaria marsupiata by d’Hondt (1975), without any further comments, are very close to N. clausus owing to the presence of a distal oral spine, small lateral avicularia, and fewer fissures in the scutum than N. saojorgensis sp. nov. However, d’Hondt (1975) recorded the specimens from eight stations: four within the Azores archipelago, two from stations west of the western Azorean islands (i.e., closer to the type location of N. clausus ), and two from stations several hundred kilometres north of the Azores. While the exact origin of the figured specimens cannot be retraced, it is likely that two or more species were combined under the name N. marsupiata in that study. These samples could not be analysed during the present project, as most of them are not present at the MNHN.

Notoplites saojorgensis sp. nov., as most other Notoplites spp., occurs at bathyal depths. The colonies are anchored in soft sediments via a single stalk formed by numerous long rootlets.

Figures

Fig. 1. Notoplites saojorgensis sp. nov. (MNHN 4163, holotype). A. Optical image of colony showing the porcelain white zooecia. B. Overview of colony showing several internodes and branch bifurcations. C. Proximal part of the colony with numerous, closely joined rhizoids emanating from proximal and abfrontal zooids, forming supporting stalks. D. Abfrontal side of internode with two rhizoids. E. Autozooids at branch bifurcation; note the basal part of the greatly enlarged spine at the base of the scutum (lower arrow) and the single spine of normal size in the median zooid at the bifurcation point (upper arrow). F. Close-up of autozooid with distolateral and proximal avicularium. G. Ovicellate zooids; note the proximomedian, acutely triangular window in the ooecium. Scale bars: A, B = 1 mm; C, D = 200 µm; E, G = 100 µm; F = 50 µm.