Hemicyclopora, Norman, 1894

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 : 391-393

“ Hemicyclopora ” pytheasi n. sp.

( Fig. 9 A-G; Tables 1 ; 3 ; 4 )

urn:lsid:zoobank.org:act:5A983DF5-F216-42D8-A4EF-3721F1663EF7

? Hemicyclopora multispinata – Hayward & Ryland 1999, fig. 46D.

TYPE LOCALITY. — La Chapelle Bank, Armorican margin.

TYPE MATERIAL. — Holotype. NE Atlantic. France • 1 large colony, c. 80 zooids with a great proportion of ovicells (> 50%) and large interzoecial kenozooids; R/V Jean Charcot; Biaçores Stn 259; off Brittany, La Chapelle Bank ; 48°01.3’N, 7°51.5’W; 190 m depth; 19.XI.1971; on shell; Dre; H. Zibrowius leg.; MNHN-IB-2017-770 .

Paratypes. NE Atlantic. France • 1 large colony, c. 60 autozooids (18 ovicells) + 2 ancestrulae budding 1 and 3 daughter zooids; R / V Jean Charcot; Biaçores Stn 259, off Brittany, La Chapelle Bank ; 48°01.3’N, 7°51.5’W; 190 m depth; 19.XI.1971; on shell; Dre; H. Zibrowius leg.; PMC. B33.5.5.2021 • coated fragment of colony and detached orifices, same origin as holotype; MNHN-IB-2017-775 • 3 ovicellate colonies; JPL-Stn G61 (710), Bay of Biscay , 44°54’N, 02°11’W; 200 m depth; III.1967; on pebble; Dre; J. P. Lagardère leg.; MNHN-IB-2017-776 • juvenile colony with ancestrula, coated, same origin as holotype; MNHN-IB-2017-777.

OTHER MATERIAL EXAMINED. — NE Atlantic. France • 1 colony; R / V Jean Charcot; Biaçores Stn 257, 47°57’N, 07°51.5’W; 335 m depth; 19.XI.1971; on Madrepora oculata ; Dre, H. Zibrowius leg.; MNHN • 1 colony; R / V Jean Charcot; Biaçores Stn 259; same data as holotype and paratype PMC. B33.5.5.2021; on bivalve shell .

ETYMOLOGY. — In honour of Pytheas, famous antique astronomer and sailor, citizen of Massalia (ancient Greek name of Marseille), who explored the northern seas during the 4th century B.C., and in reference to the geographical distribution of this species.

DIAGNOSIS. — Autozooids separated by deep grooves, frontal shield convex with mamillate texture, marginal pores large. Distal wall subvertical. Orifice terminal, condyles indistinct and relatively square, without lyrula-like protuberance; proximal edge of secondary orifice clearly convex with round top. Oral spines eight in both ovicellate and non-ovicellate zooids; spines of the proximalmost pair clearly converging; in ovicellate zooids, bases of the distal pair adjoining the ovicell. Ovicell apparently acleithral, attached to distal wall of maternal zooid, terminal and produced by a small, basal kenozooid; endooecium smooth, without proximal thickening. Large, interzooidal, porous kenozooids occasionally present. Ancestrula with opesia, cryptocyst and gymnocyst equally extended, five spines around the cryptocyst, 4-6 spines around the opesia.

DESCRIPTION

Colony encrusting, unilaminar, small to medium-sized. Autozooids large, elongated (L/W ratio = 1.48), distinctly separated by deep grooves, laid out in quincunx; frontal shield convex, smooth, slightly mamillated; marginal pores large (15-30 µm), distally arranged in a double or triple row and proximally in a single row ( Fig. 9 A-C). Distal wall subvertical ( Fig. 9B, C, E ), its inner side visible in ovicellate zooids as a broad, vertical frame below the ovicell opening and between the distalmost pair of spines ( Fig. 9D ). Orifice distal; primary orifice as long as wide or slightly longer, its calcified ring with step-shaped proximal ends, i.e., without prominent condyles; inner proximal side smooth and without any protuberance ( Fig. 9G ); proximal edge of secondary orifice clearly convex, with round top and without umbo ( Fig.9 B-D, F). Oral spines eight in ovicellate and non-ovicellate zooids, long (200-250 µm), huddled together, with thick, prominent bases, the proximalmost pair clearly convergent ( Fig. 9D, F ). Ovicells frequent, globular, sometimes remarkably wide, with surface structure of endooecium similar to that of frontal shield, without proximal protuberance, seemingly not closed by the operculum, attached to the vertical distal wall of the maternal zooid, apparently terminal and free ( Ostrovsky 2013: 125, 129), but produced by a small, poorly visible, basal kenozooid at the colony margin ( Fig. 9B, C ). Pore chambers numerous. Large interzooidal kenozooids occasional, with porous frontal shield ( Fig. 9D ). Ancestrula with proximal rim of opesia concave, proximal gymnocyst broad, five spines at the cryptocyst periphery, and four, five or six spines bordering the opesia ( Fig. 9E ).

REMARKS

Morphological features

The morphological features of “ H.” pytheasi n. sp. are very similar to those of E. similis and “ E.” massiliana n. sp., except for the structure of the primary orifice. Unlike other species of the same species complex, the internal side of the convex proximal edge of the orifice of “ H.” pytheasi n. sp. is smooth, without any bulge that could be identified as a lyrula ( Fig. 9G ). In the absence of such structure, does the convex edge of the orifice play the function of a lyrula and can stop the open operculum in a vertical position? The respective position of the maternal orifice and the ovicell suggests that the latter is acleithral ( Fig. 9C, D ), as in typical Escharella species. However, this feature remains incertain without specific anatomical investigation. Therefore, pending a molecular approach, this species was placed in the genus Hemicyclopora in quotation marks. Colonies of “ H”. pytheasi n. sp. often have a great proportion of ovicellate zooids, e.g.> 50% in the holotype specimen, and even more in two other colonies (Stn JPL-G61: 59%; Biaçores Stn 259: 74%). This high fertility was observed in most colonies (mean: 39 ± 24%) and likely has a specific significance. The occurrence of large interzoecial kenozooids ( Fig. 12D ) has been only observed in specimens from the Armorican Margin (Biaçores st. 259).

Taxonomic issues

“ Hemicyclopora ” pytheasi n. sp. shows obvious morphological similarities with “ H.” celtica n. sp. with which it can coexist along the Armorican margin. These species share the same shape of the secondary orifice and the presence of eight spines in non-ovicellate zooids. However, “ H.” pytheasi n. sp. differs in the external aspect of the frontal shield and endooecium (mamillated vs granular), the size of the marginal pores (large vs tiny), the condyles (step-shaped vs protuberant), and the ovicellate zooids. The latter differ in the number of spines in ovicellate zooids (eight in “ H.” pytheasi n. sp. vs six in “ H.” celtica n. sp.), and the building of ovicells, which involves a basal kenozooid (“ H.” pytheasi n. sp.), instead of a distal autozooid (“ H.” celtica n. sp.) ( Table 3 ). The co-occurrence of these two species in the same depth zone of the same geographical area (Armorican margin) confirms the validity of these observed differences for discriminating them at species level. The specimen figured without indication of origin by Hayward & Ryland (1999: fig. 46D) and attributed to H. multispinata shows some typical features of “ H.” pytheasi n. sp.: proximal edge of the orifice typically convex, ovicellate zooid with eight spines, and large marginal pores. On the other hand, the drawing illustrating H. multispinata by the same authors ( Hayward & Ryland 1999: fig. 49) might be attributed as well to “ H.” pytheasi n. sp. or to “ H.” celtica n. sp. because of the lack of information concerning the ovicellate zooids and the shape of condyles.

HABITAT DISTRIBUTION

Colonies of “ H.” pytheasi n. sp. encrusted small substrates (empty shells, fragmented skeletons of Madrepora oculata , pebbles) at the edge of the continental shelf (190-335 m).

GEOGRAPHICAL DISTRIBUTION

The examined material came from the Armorican margin and the Bay of Biscay.

Figures

FIG. 9. — “Hemicyclopora” pytheasi n. sp.: A, colony with many ovicells and its ancestrula; another ancestrula with a single daughter zooid, both marked (a); B, ovicellate zooids with converging oral spines; C, ovicellate and non-ovicellate zooids, with a small zooid regenerated inside a broken cystid; D, distal part of two ovicellate zooids and an interzooidal porous kenozooid; E, juvenile colony with ancestrula; F, distal part of a non-ovicellate zooid, orifice with typically convex proximal edge; G, inner side of an orifice showing the lyrula-like suboral umbo and three basal pores of spines (partly visible on the right side). Origin: Atlantic, Armorican margin; Biaçores Stn 259; A, B, paratype PMC-B33.5.52021; C, D, F, G, paratype MNHN-IB-2017-775; E, paratype MNHN-IB-2017-777. Scale bars: A, 1 mm; B, C, E, 200 µm; D, 100 µm; F, G, 50 µm.

FIG. 12. — Hemicyclopora hexaspinae n. sp.: A, ancestrula, note the large size of the cryptocyst; B, ancestrula and daughter zooids; C, autozooid with a tubule budded from a distolateral pore-chamber; D, ancestrula with three successive daughter zooids, the third one with a basal tubular part budded by the ancestrula; E, same ancestrula and zooids, sketch from stereomicroscopic examination: darkening by Mn-Fe oxides increasing from the youngest zooid to the ancestrula attesting to the very slow growth in confined dark caves. Origin: A, C-E, Provence, 3PP Cave; B, Ustica Island, Apollo Bank. Scale bars: A, 50 µm; B, 300 µm; C-E, 100 µm.