Pentapora ottomulleriana, (MOLL, 1803)

Lombardi, Chiara, Taylor, Paul D. & Cocito, Silvia, 2010, Systematics of the Miocene-Recent bryozoan genus Pentapora (Cheilostomata), Zoological Journal of the Linnean Society 160 (1), pp. 17-39 : 26-29

PENTAPORA OTTOMULLERIANA ( MOLL, 1803) ( FIG. 7 )

Eschara otto-mulleriana: Moll, 1803: 60 .

Lepralia pallasiana var. projecta Waters, 1878 : pl. 1, fig. 17; Waters, 1879: 42, pl. 18, fig. 3; Jelly, 1889: 131; Calvet, 1902: 25.

Hippodiplosella spinosissima: Barroso, 1920: 7, text-fig.

Lepralia Otto Mulleriana Waters, 1923: 548 , pl. 17, figs 1–2, 5–7; Waters, 1925: 539, pl. 29, fig. 20; Waters, 1926: 428, pl. 18, fig. 8.

Hippodiplosia granulosa: Canu & Bassler, 1925: 31 , pl. 3, figs 2–3, pl. 7, figs 6–7.

Hippodiplosia otto-mulleriana Canu & Bassler, 1927: 35 ; Canu & Bassler, 1930: 49, pl. 6, figs 8–9.

Lepralia otto-mulleriana Calvet, 1927: 30 .

Hippodiplosia ottomulleriana Gautier, 1962: 66 .

Pentapora ottomulleriana Zabala, 1986: 403 , fig. 133; Zabala & Maluquer, 1988: 115, fig. 237, pl. 8, figs F–G.

Material examined: NHM 99.7.1.1749, Mediterranean, Busk Collection. NHM 2007.9.14.16, on rhizomes of Posidonia oceanica, Monterosso al Mare, Ligurian Sea , Italy, 44°08.30 ′ N, 9°38.00 ′ E, 10 m, 2001, Lombardi & Cocito Collection , 2001. Attempts to locate Moll’s type material have been unsuccessful .

Revised diagnosis: Pentapora with encrusting colonies; autozooids moderately large, averaging 0.75 mm long by 0.48 mm wide, frontal shield knobbly; avicularia monomorphic, large, spatulate; ovicell with numerous, evenly distributed pores.

Description: Colony encrusting, unilameller. Early astogeny unknown.

Autozooids longer than wide, 0.58–0.97 mm long (mean 0.75 ± 0.05 mm; N = 10) by 0.37–0.61 mm wide (mean 0.48 ± 0.05 mm; N = 10), roughly rectangular in shape, arranged quincuncially with distinct zooidal boundaries, surface knobbly. Primary orifice 0.24– 0.29 mm long (mean 0.27 ± 0.01 mm; N = 10) by 0.17– 0.22 mm wide (mean 0.2 ± 0.01 mm; N = 10); condyles present; oral spines numbering 4–9, placed all around the anter. Basal walls lacking median septum. Multiporous septula present in lateral and transverse vertical walls. Ovicells averaging 0.28–0.44 mm long (mean 0.34 ± 0.03 mm; N = 10) by 0.32–0.48 mm wide (mean 0.41 ± 0.03 mm; N = 10), periphery knobbly, resembling a frontal shield; pores numerous, distributed more or less evenly, some elongate and aligned radially.

Avicularia adventitious, normally suboral, directed proximally, large (giant), 0.21–0.26 mm long (mean 0.24 ± 0.01 mm; N = 5) by 0.13–0.17 mm wide (mean 0.14 ± 0.01 mm; N = 5); rostrum spatulate; orifice 0.11 ± 0.01 mm long by 0.08 ± 0.01 mm wide (N = 5); crossbar calcified, averaging 0.09 ± 0.01 mm long (N = 5). Sporadic lateral avicularia, acute to the frontal plane, observed in some colonies from Croatia (M. Novosel Collection, Zagreb).

Remarks: Apart from having an exclusively encrusting colony form, P. ottomulleriana can be distinguished from the other species of the genus by the knobbly frontal shield calcification and the numerous, basally articulated oral spines ( Fig. 7A, D–F ). Avicularia are monomorphic, and, judging by their large size and overall morphology ( Fig. 7D, F ), they are more likely to be homologous with the giant avicularia of other species of Pentapora than with the normal-sized avicularia.

Distribution: Mediterranean Sea, including Spain, France, Algeria, Tunisia, and Italy ( Zabala, 1986); Croatia (M. Novosel, pers. comm., 2008).

PENTAPORA PERTUSA ( MILNE EDWARDS, 1836)

( FIG. 8 )

Eschara pertusa: Milne Edwards, 1836: 9 , pl. 10, figs 3, 3°, 3b, 3c; Busk, 1859: 65 (part), pl. 10, figs 2a, 2a ′ only.

non Eschara pertusa Michelin, 1840: 330 , pl. 79, fig. 2.

Material examined: NHM B1651, D37800-5, D55498, Pliocene, Coralline Crag Formation, Suffolk. NHM D34873-4, Coralline Crag Formation , Broom Pit , Reid Collection. NHM D51059 , Coralline Crag Formation , Crag Pit Nursery ( NGR 458580 ), Aldeburgh, Suffolk, Pitt Collection, 1967. NHM D50182, Coralline Crag Formation, Broom Pit, Gedgrave, Suffolk, Burrows Collection. NHM BZ 5643, Coralline Crag Formation, Aldeburgh Mbr, Aldeburgh Hall, Suffolk, Wilson & Taylor Collection. NHM BZ 5644, Coralline Crag Formation, Broom Pit, Gedgrave, Suffolk, Wilson & Taylor Collection. NHM BZ 5645 (sample), Coralline Crag Formation, Sudbourne, Suffolk, Whiteley Collection. NHM BZ 5646 (sample), BZ 5647, Coralline Crag Formation, Crag Farm, Sudbourne, Suffolk, Whiteley Collection. NHM BZ 5676, Coralline Crag Formation,? Ramsholt Member, Broom Pit, Gedgrave, Suffolk, Lombardi Collection, August 2007 .

D’Hondt (2006: 29) listed the type of this species (as Hippopleurifera pertusa ) as no. 4553 in the Milne Edwards Collection of the Museum National d’Histoire Naturelle, Paris.

Revised diagnosis: Pentapora with erect, foliaceous colonies; autozooids large, averaging 0.81 mm long by 0.31 mm wide; avicularia dimorphic, the giant avicularia very large with triangular rostra; ovicell with a single central pore.

Description: Colonies developing three-dimensional, box-like growth comprising folded and anastomosing bilamellar plates from an extensive encrusting base.

Autozooids longer than wide, 0.75–0.92 mm long (mean 0.81 ± 0.06 mm; N = 10) by 0.24–0.31 mm wide (mean 0.27 ± 0.03 mm; N = 10), roughly rectangular in shape. Frontal shield lepralioid, slightly convex, granular, with areolar pores and pseudopores. Primary orifice longer than wide, 0.11–0.21 mm long (mean 0.17 ± 0.03 mm; N = 10) by 0.11–0.19 mm wide (mean 0.16 ± 0.03 mm; N = 10); condyles present. No oral spines. Basal walls with short median septum extending distally from transverse wall. Ovicells globular, slightly wider than long, averaging 0.24 ± 0.01 mm long by 0.31 ± 0.02 mm wide (N = 10), with one large central pore; not enveloped by secondary calcification.

Avicularia dimorphic, adventitious, suboral, proximally directed. Normal avicularia small, as long as wide, mean length and width 0.09 ± 0.01 mm (N = 10), located on a suboral umbo; crossbar calcified. Giant avicularia occasionally replacing normal avicularia, very large, 0.34–0.51-mm long (mean 0.42 ± 0.07 mm; N = 10) by 0.18–0.24-mm wide (mean 0.25 ± 0.04 mm; N = 10) wide, prominent, occupying more than half of the frontal shield; rostrum triangular, acute to the frontal plane, raised at distal end; palate long; crossbar with columella.

Remarks: Milne Edwards (1836, pl. 10, fig. 3C) depicted an example of one of the large and pointed giant avicularia that are characteristic of this species in his material from the [Coralline] Crag of Sudbourne, Suffolk. Thus it is clear that his description refers to P. pertusa rather than the sympatric P. lacryma sp. nov. (described below), in which the giant avicularia are smaller and spatulate. The uniporous ovicells ( Fig. 8D ) are another feature of P. pertusa enabling its distinction from P. lacryma sp. nov., and indeed all other species of Pentapora . References to this species without illustrations (e.g. Buge, 1957) are impossible to evaluate, as are putative examples lacking the diagnostic giant avicularia or uniporous ovicells (e.g. El Hajjaji, 1992; Pouyet & Moissette, 1992; Haddadi-Hamdane, 1996).

Most specimens of P. pertusa and the co-occurring P. lacryma sp. nov. from the Coralline Crag Formation of Suffolk come from shell limestones leached of aragonite (see Balson, 1983). Given that the frontal shields of recent P. foliacea and P. fascialis have a thick outer coating of aragonite that is added during late ontogeny ( Taylor, Kudryavtsev & Schopf, 2008), the loss of this diagnetically unstable layer may have altered the appearance of the fossil colonies, as compared with the pristine skeleton. In particular, any lappets or secondary overgrowths of ovicells may not be preserved in aragonite-leached fossils of Pentapora .

Distribution: Pliocene, Late Zanclean–Early Piacenzian, Coralline Crag Formation, Aldeburgh, and Sudbourne members, questionably Ramsholt Member, Suffolk, UK.

Figures

Figure 7. Pentapora ottomulleriana (Moll, 1803), Monterosso al Mare, Liguria, Italy, NHM 2007.9.14.16; scanning electron micrographs of uncoated specimens imaged using back-scattered electrons. A, autozooids. B, ovicell. C, young zooids at the growing edge. D, autozooids and an avicularium. E, primary orifice. F, avicularium. Scale bars: A = 600 Mm; B = 100 Mm; C = 350 Mm; D = 200 Mm; E = 75 Mm; F = 130 Mm.

Figure 8. Pentapora pertusa (Milne Edwards, 1836), scanning electron micrographs of uncoated specimens from the Pliocene Coralline Crag Formation of Suffolk, England, imaged using back-scattered electrons. A, autozooids and several giant avicularia, Broom Pit, NHM D50182. B, ovicellate zooids and giant suboral avicularium with details obscured by diagenetic cement, Aldeburgh Member, Aldeburgh Hall, NHM BZ 5643. C–F, NHM BZ 5676,?Ramsholt Member, Broom Pit. C, patch of colony dominated by ovicellate zooids. D, ovicells and normal suboral avicularia. E, orifice and normal suboral avicularium. F, giant triangular suboral avicularium. Scale bars: A = 280 Mm; B = 190 Mm; C = 520 Mm; D = 220 Mm; E = 60 Mm; F = 100 Mm.