Scutocyclopora dentata ( López de la Cuadra & García-Gómez, 1991 ) Harmelin & Rosso, 2023

Harmelin, Jean-Georges & Rosso, Antonietta, 2023, On some “ Hemicyclopora ” Norman, 1894 and “ Escharella ” Gray, 1848 species (Bryozoa, Cheilostomatida) from the Atlantic-Mediterranean region. Re-examination of their generic status and description of new species and a new genus, Zoosystema 45 (10), pp. 373-407 : 399-402

Scutocyclopora dentata ( López de la Cuadra & García-Gómez, 1991) n. comb.

( Figs 14B ; 15 A-F; Tables 1 ; 4 )

Hemicyclopora dentata López de la Cuadra & García-Gómez, 1991: 213 , fig. 2A-C, pl. 1.

Hemicyclopora collarina Canu & Lecointre, 1930 . — Harmelin 2003: 108, fig. 4. — Ayari-Kliti et al. 2012: 90, pl. 3, fig. 2A-C.

Hemicyclopora sp. – Zabala 1993: 567.

Hemicyclopora sp. 1 – Rosso et al. 2021 a: fig. 6H, table 1.

Not Hemicyclopora collarina Canu & Lecointre, 1930: 106 , pl. 14, fig. 3-5. — Buge 1957: 313. — Moissette 1988: 158, pl. 26, fig. 1, 4.

MATERIAL EXAMINED. — France, Provence • 3 colonies; Cassis, Trémies Cave ; 43°12’00”N, 5°30’43.5”E; 6 m depth; 7.I.1982; dark zone; on stalactite and bryozoan nodules; Div; JGH leg.; MNHN • 1 colony; Port-Cros Is., Bagaud Cave ; 43°00’46”N, 6°21’36”E; 5 m depth; III.1985; dark zone; on rocky wall; Div; JGH leg .; MNHN. Spain, Balearic Archipelago • 1 colony; Mallorca Is.; Stn MZ _M.120 (13); 7 m depth, on Posidonia rhizome; Div ; M. Zabala leg.; MNHN • 1 colony; Cabrera Is.; Stn MZ M.8 (27); depth missing, on Posidonia root; Div; M. Zabala leg.; MNHN • 1 small ovicellate colony; Mallorca Is.; Stn MZ 415 ; depth missing, on lower side of a biogenic concretion; Div; M. Zabala leg.; MNHN . Italy • 1 dead colony fragment; Tyrrhenian Sea, Campania, Palinuro Cape, Scaletta Cave ; 40°1’35”N, 15°16’7”E; 46 m depth; 14.IX.2009; dark zone; Div; R. Leonardi leg.; PMC Rosso-Collection I. H. B. 93a .• 1 living and two dead small ovicellate colonies; lu Lampiùne Cave ; 40°08’05.7”N, 18°31’00.4”E; 8 m depth; 2003; dark zone; Div; G. Belmonte leg.; MNHN • 1 colony with ancestrula; Sicily, Ionian Sea, off Avola, c. 100 m depth; 2005; coralligenous bottoms; fishermen Dre ; AR leg.; PMC Rosso-Collection I. H. B. 93b • 1 ovicellate colony fragment; NW Sardinia, Capo Caccia-Isola Piana MPA, Bisbe Cave ; 40°35’40”N, 8°11’39”E; 5 m depth; VI.2009; on wall of semi-dark zone; Div; V. Di Martino leg.; PMC Rosso-Collection I. H. B. 93c .

SEM PHOTOS EXAMINED. — Spain • Holotype; La Atunara; López de la Cuadra leg. (personal communication to JGH, XII.1988); paratypes I & II stored at the MNHN: MNHN-IB-2008-12741 , data available at http://coldb.mnhn.fr/catalognumber/mnhn/ib/2008- 12741 • 1 large colony with 5 ovicells and ancestrula; Cape Castel, Montgri; Stn ST 9144; 42°4’57.22”N, 3°12’6.67”E; 27 m depth; T. Madurell leg. (personal communication to JGH, 05.III.2020). Croatia • 1 large colony; Kornati Archipelago; 33 m depth; COR with gorgonians; M. Novosel leg. (personal communication to JGH, 20.I.2011).

DESCRIPTION

Colony small, encrusting, multiserial, unilaminar. Autozooids separated by deep grooves, arranged quincuncially; frontal shield clearly convex, surface distinctly structured by large (c. 20-30 µm in diameter) hemispherical tubercles ( Fig. 15 B- E) with a glassy appearance, imperforate except for relatively large (19-35 µm) marginal pores, arranged in a single row which doubles distally, laterally to the orifice ( Fig. 15A, D ). Pore-chambers small (c. 30 µm wide), numerous (>10 on each side). Primary orifice rounded, wider than long in both non-ovicellate and ovicellate autozooids, with proximal edge slightly concave, condyles step-shaped at the extremities of a wide internal arc ( Fig. 15A, D, E ); operculum light yellow. No oral spines. Secondary orifice of non-ovicellate zooids forming a high, collar-shaped peristome, more or less flared with an upper rim irregularly waved or with some indentations, interrupted proximally by a rounded notch sometimes indented with a triangular process (pseudo-spine) at the upper corners ( Fig. 15B, D ); in ovicellate zooids, peristomial collar higher, often indented with irregularly triangular pseudo-spines, distally contiguous to the ovicell ( Fig. 15A, C, E ). Ovicell hyperstomial, cleithral, attached to the distal wall of maternal zooid, most likely associated with a small, basal kenozooid, endooecium noticeably tuberculate, with proximal rim (distal edge of orifice) topped by a prominent vizor with smooth surface and convex to triangular upper edge, which can be indented in specimens from caves ( Fig. 15A, C, E ). Ancestrula resembling later zooids ( Figs 14B ; 15F ), with umbonuloid frontal shield, entirely calcified, markedly convex and nodular; orifice rounded, without spines but encircled by a flared peristome with the edge waved or scalloped, with some indentations separated by few small triangular processes (pseudo-spines), a little smaller than in “adult” zooids, but slightly wider than the periancestrular zooids.

REMARKS

Morphological features and taxonomic issues

All specimens of Scutocyclopora dentata n. comb. from our collections or examined from SEM photos (14 colonies from 12 Mediterranean localities and various habitats: see below) showed the same readily apparent morphological traits that clearly discriminate this species from all Hemicyclopora species. The frontal shield and the endooecium, covered with large nodules, have a very particular aspect, but the obvious uniqueness of this species is given by features of the orifice area and the ancestrula. The lack of oral spines, which are replaced by a high and more or less serrated collar, prolonged with a prominent, arched vizor on the ovicell, is a constant feature. Similarly, all observed ancestrulae, including the one of the type ( López de la Cuadra & Garcia-Gómez 1991, text-fig.2B; pl. 1, fig. 1 and SEM photo sent to JGH), are similar to the following autozooids, just a little smaller ( Figs 14B ; 15F ; Table 1 ). Therefore, this type of ancestrula differs drastically from the tatiform ancestrula characterizing both Hemicyclopora (e.g. H. polita , the type species of the genus: Fig. 14A ) and Escharella . The latter type shows in frontal view three distinct parts, a distal opesia with a slightly concave proximal edge that is framed by oral spines, a cryptocystal area, also edged by several spines, and a lateral and proximal gymnocystal area. Curiously, the ancestrula of S. dentata n. comb. bears a superficial resemblance with that of the hippoporidrid Scorpiodinipora costulata (Canu & Bassler, 1929) ( Harmelin et al. 2012: fig. 6). Variability of these discriminating characters only concerns the shape of the peristomial collar, more or less scalloped, with indentations and pointed processes that may be reduced or form pseudo-spines ( Fig. 15 A-D). However, some morphological traits are similar to those of Hemicylopora, such as the colony shape, the general structure of the orifice, the ovicell and the frontal shield.

Recent material of S. dentata n. comb. was attributed by Harmelin (2003) and Ayari-Kliti et al. (2012) to the fossil species Hemicyclopora collarina Canu & Lecointre, 1930 from the Faluns of Touraine and Anjou. This species was defined by Canu & Lecointre (1930: 106) with the following characters “Les zoécies sont distinctes, séparées par un sillon profond, un peu allongées, ovoïdes ou subhexagonales […] frontale très convexe […] entourée de minuscules pores aréolaires […] deux cardelles profondes […] grand anter, plus petit poster droit ou concave, […] péristomie très évasée, très irrégulière, dont la lèvre proximale est très large, […] L’ovicelle est grande, très globuleuse, lisse […]”, and 4-6 spines are present. This species was similarly characterized by Buge (1957: 313). The figures given by Canu & Lecointre (1930: pl. 14, figs 3-5) show true spines and not spinous indentations of the peristomial collar, such as in Recent specimens of S. dentata n. comb. Moreover, the remark by Canu & Lecointre (1930: 107) that H. collarina resembles H. labiosa ( Jullien, 1903) , a typical Hemicyclopora species from the Azores with six to eight spines and a high peristome, implies a clear difference to S. dentata n. comb. The description and SEM figures of fossil specimens from the Messinian of Oran ( Algeria) ascribed to H. collarina by Moissette (1988) depict a very convex and finely granular frontal shield, an orifice with a straight proximal edge and small condyles, a peristome with high lateral wings, and four spines with large bases in ovicellate zooids. The ancestrula of H. collarina is not known.

Scutocyclopora dentata n. comb. shows some superficial similarities with Hemiphylactella pulchra Vigneaux, 1949 , the type species of the genus Hemiphylactella Vigneaux, 1949 , from the early Miocene of Aquitaine ( France) ( Di Martino & Taylor 2017: 784, fig. 1A-E). The two species share a nodular frontal shield with peripheral pores and a large, flared peristome which extends on the proximal rim of the ovicell. However, H. pulchra has 1-3 oral spines and a wider, flatter and thicker peristome, besides autozooids with a less convex frontal shield and fewer but larger areolar pores, and relatively smaller ovicells.

The placement of Scutocyclopora n. gen. in the same family as Hemicyclopora and Escharella , i.e., in Escharellidae , is quite questionable considering the features of the ancestrula. Obviously, the phylogenic relationships of this taxon will require a molecular approach.

HABITAT DISTRIBUTION

Scutocyclopora dentata n. comb. is distributed in a wide variety of coastal habitats with apparently contrasting ecological features within the Infralittoral and the Circalittoral zones (depth range: 5-100 m), but with a clear tendency to sciaphily, i.e., a preference for mesophotic and dark habitats or microhabitats. This species was first found ( López de la Cuadra & García-Gómez 1991) on stones and shell fragments at 30-50 m depth. Subsequent records span widely across different types of habitats: 1) coarse debris on detritic sand in northern Tunisia ( Ayari-Kliti et al. 2012); 2) rocky walls of submarine caves in complete darkness at shallow depth in Provence ( Harmelin 2003), southern Italy and Sardinia ( Rosso et al. 2021 a, present paper), and Catalonia (Medes Isles: T. Madurell & M. Zabala, person. com. to JGH, 1.II.2021); 3) biogenic concretions and stones in coralligenous bottoms with Paramuricea clavata (Risso, 1826) ( Croatia, 33 m, M. Novosel leg.; Catalonia, 26-41 m, T. Madurell & M. Zabala, person. com.); and 4) debris of rhizomes and roots of Posidonia oceanica (Delile) from the Balearic Islands ( Zabala 1993 and leg.; T. Madurell & M. Zabala, person. com. to JGH, 1.II.2021). However, the apparent ecological heterogeneity of these microhabitats may be misleading as undersides of small substrata may offer to tiny encrusting bryozoan colonies conditions similar to those of a large cavity (e.g. Harmelin 2000, 2003).

GEOGRAPHICAL DISTRIBUTION

The examined material of Scutocyclopora dentata n. comb. was collected in various localities of the Mediterranean: in Spain (Andalusia, López de la Cuadra & Garcia-Gómez 1991; Catalonia, Madurell & Zabala, unpublished data; Balearic Islands, Zabala 1993 as Hemicyclopora sp. & unpublished data), France (Provence: Harmelin 2003 and present material), Italy (Campania, SE Sicily, S Apulia and NW Sardinia: Rosso et al. 2021 a, present material), Croatia (Kornati Archipelago: M. Novosel, unpublished data), and northern Tunisia (east of Zembra Island: Ayari-Kliti et al. 2012).

Figures

FIG. 14. — Oral spines in a non-ovicellate zooid of Hemicyclopora polita (Norman, 1864): A, outside view of four spines with tall bases; B, inside view of the orifice area showing four pores corresponding to the opening of spines into the coelom and the distal part of the umbonuloid frontal shield.Ancestrula and early astogeny in the genera Hemicyclopora and Scutocyclopora n. gen.: C, H. polita, D, S. dentata n. comb, Origin: A-C, NE Atlantic, Armorican Margin, 1050 m, R/V Thalassa Z435; D, Ionian Sea, Sicily, off Avola, 100 m. Scale bars: A, B, 100 µm; C, D, 200 µm.

FIG. 15. — Scutocyclopora dentata (López de la Cuadra & García-Gómez,1991) n. comb.: A, one non-ovicellate and three ovicellate zooids;B, two non-ovicellate zooids with high, indented peristome; C, E, ovicellate zooid with nodular frontal shield and endooecium and orifice edged by a vizor on the ovicell and a collar with pseudo-spines; D, non-ovicellate zooid with indented collar, orifice with internal arch ending in step-shaped condyles, and small marginal pores; F, young stage of a colony with ancestrula. Origin of specimens: A, Italy, Campania, Palinuro Cape, Scaletta Cave, 47 m; B, E, France, Port-Cros, Bagaud Cave, 5 m; C, France, Provence, Trémies cave, 6 m; D, F, Italy, Sicily, off Avola, 100 m. Scale bars: A, C, 200 µm; B, D, E, 100 µm; F, 300 µm.