Hemicyclopora neatonensis, 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 : 377-381

Hemicyclopora neatonensis n. sp.

( Figs 2 A-F; 3A-F; 10A-C; Tables 1 ; 2 ; 4 )

urn:lsid:zoobank.org:act:8496B9F0-8BEC-4A27-9DE2-CE1876BFB8BA

Hemicyclopora multispinata – Rosso 1989: tables 3c, 4c, 6c, pl. 8, fig. A.; 1996a: 195, 210, pl. 4, fig. A.; 1996b: 60 (table 1) — Di Geronimo et al. 1994: 103 (table 3). — Chimenz & Faraglia 1995: 40, pl. 2, figs A, B. —? Morri et al. 1999: 733 (table 1). — Rosso & Sanfilippo 2005: 111 (table 1). — Chimenz Gusso et al. 2014: 172, fig. 88a-d. — Rosso & Di Martino 2016: 579 (table 1).

TYPE LOCALITY. — Italy, SE Sicily, Gulf of Noto.

TYPE MATERIAL. — Holotype. Mediterranean, Italy, Ionian Sea, SE Sicily, Gulf of Noto • 1 large colony with several ovicells; Gulf of Noto, Stn PS 81-9D; 36°45’N, 15°12’E; 78 m depth; VII.1981; on a small rhodolith; Dre; I. Di Geronimo leg.; PMC. B34.1.4.2021a . Paratypes. Mediterranean, Italy, Ionian Sea, SE Sicily, Gulf of Noto • 1 colony with 3 autozooids and ancestrula; same data as the holotype; on a small rhodolith; PMC. B34.1.4.2021b1 • 1 dead ovicellate colony; same data as the holotype; on a small rhodolith; PMC. B34.1.4.2021b2 • 1 living ovicellate colony; same data as the holotype; on a small rhodolith; PMC. B34.1.4.2021b3 • 1 living ovicellate colony; same data as the holotype; on a bivalve shell; PMC. B34.1.4.2021b4 • 1 living ovicellate colony; SE Sicily, Gulf of Noto; Stn PS 81-CR1; 36°44’N, 15°10’E; 45 m depth; on a bivalve shell; PMC. B34.1.4.2021b5 • 1 living colony; same data as PMC. B34.1.4.2021b5; on a rhodolith fragment; PMC. B34.1.4.2021b6 • 1 coated colony, same data as PMC. B34.1.4.2021b5; MNHN-IB-2017.769. All samples collected in VII.1981; Dre; I. Di Geronimo leg.

OTHER EXAMINED MATERIAL. — Mediterranean, Italy, Ionian Sea, SE Sicily, Gulf of Noto • 18 fragments; Stn PS 81-9D; same data as the holotype; PMC Rosso-Collection I. H. B. 92a • fragments, Stn PS 81-2XB; 120 m depth; PMC Rosso-Collection I. H. B. 92a • fragments, Stn PS81-6D; 96 m depth; PMC • 25 fragments; Stn PS 81-9C; 83- 74 m depth; on rhodoliths, mollusc and brachiopod shells; PMC Rosso-Collection I. H. B. 92a • fragments; Stn PS 81-2C; 60 m depth. All samples collected in VII.1981; Dre; I. Di Geronimo leg.; PMC Rosso-Collection I. H. B. 92a.

SEM PHOTOS EXAMINED. — Italy • Adriatic Sea, Puglia, Brindisi, 27 m depth, CR bottom, C. Chimenz leg. (sent to JGH, 30.VI.1995) .

ETYMOLOGY. — From Neaton, ancient Greek name of the town of Noto, SE Sicily, close to the shore of the Gulf of Noto.

DIAGNOSIS. — Autozooids bulged, frontal shield with round granules, marginal pores medium- to large-sized. Orifice terminal or subterminal, primary orifice with prominent and down-curved condyles; proximal edge concave, bordered by a low semi-circular collar. Oral spines usually eight in non-ovicellate and six in ovicellate zooids. Ovicell recumbent on the frontal shield of the distal zooid, with a low proximal visor, ooecium produced by a small basal kenozooid, occasionally fusing with a distal zooid or an interzooidal kenozooid. Large interzooidal kenozooids occasional. Ancestrula with opesia, cryptocyst and gymnocyst equally extended, 12 or 13 spines, the opesia with a concave proximal edge.

DESCRIPTION

Colony encrusting, unilaminar, small- to medium-sized (i.e., less than 100 zooids). Autozooids quincuncially arranged, relatively large ( Figs 2 ; 3 ; 10A, B ; Table 1 ); frontal shield bulged, its surface relief with small knobs; marginal areolar pores relatively large (20-30 µm; Fig. 2D, E ), generally in a single row with another one or two pores in an upper position at the level of the orifice ( Fig. 2D ). Pore-chambers small and numerous (10-12 on each side) ( Figs 2E ; 3E, F ). Distal wall vertical or sub-vertical ( Figs 2E ; 3E ). Orifice of non-ovicellate zooids distal or sub-distal, longer than wide ( Table 1 , ratio L/W: 1.13), wider in ovicellate zooids (25-30% in Sicilian specimens), proximal edge (poster) slightly concave, condyles large, triangular, more or less blunt ( Figs 2E ; 3C, E ; 10A, B ). A low, semi-circular collar proximal to the poster, higher when joining the most proximal pair of oral spines ( Figs 2 DF; 10A). Oral spines eight, occasionally six, seven or nine, in non-ovicellate zooids, six in ovicellate zooids ( Figs 2D, F ; 3D ). Ovicell ovoid, wider than long, cleithral ( Figs 2B, D, F ; 3C ), with a small, low, more or less arched vizor above the proximal edge, recumbent on a small ooecium-producing basal kenozooid ( Fig. 2D, F ), occasionally fusing with the frontal shield of distal daughter autozooid ( Figs 2B, C ; 3C ), or an interzooidal kenozooid ( Fig. 3B ). Interzooidal kenozooids present, nearly as large as autozooids (i.e., vicarious: Fig. 3E ) or smaller at varying extents, irregularly shaped, the frontal shield finely granular with areolar pores irregularly distributed in a peripheral band. Ancestrula with 12 spines (occasionally 13), including six or seven around the opesia, this latter with a concave proximal edge; opesia, cryptocyst and proximal gymnocyst similarly sized when measured along the central axis ( Figs 3F ; 10C ); three distal and latero-distal daughter autozooids budded by the ancestrula, similar to the following ones, but slightly smaller.

REMARKS

As in other Hemicyclopora species, the most readily accessible distinctive features of the specimens assigned here to H. neatonensis n. sp. are provided by the distal part of the zooids, i.e., the structure and shape of the orifice area, the number of oral spines, and the structure of the ovicell. Like in the type of H. multispinata , the orifice of H. neatonensis n. sp. is a little longer than broad, with a slightly concave proximal edge, proximally bordered by a low, arched crest, which becomes higher when it meets the most proximal pair of oral spines, and the condyles (not described in H. multispinata ) are large and roughly triangular. The oral spines are eight in most cases (occasionally six, seven or nine) in non-ovicellate zooids, invariably six in ovicellate zooids, and articulated on thick bases. Ovicells bear a short, arched crest near the edge of the orifice, apparently formed by the cryptocystal layer of the endooecium. The latter is built by a small basal kenozooid ( Fig. 3B ) but also, sometimes in a same colony, by a distal autozooid or an interzooidal kenozooid. The ancestrula has the same shape in these Mediterranean specimens and in the type specimen of H. multispinata , with the opesia, the cryptocyst and the proximal gymnocyst similarly extended ( Figs 3F ; 10C ), but with, seemingly, a greater number of ancestrular spines (12 or 13) in H. neatonensis n. sp. In some colonies from Sicily, a few ovicells and adjacent autozooids show a deformity ( Fig. 3A, D ) possibly resulting from their fusion. The occurrence of interzooidal kenozooids in H. neatonensis n. sp. ( Fig. 3E ), as well as in H. polita , H. discrepans (Jullien in Jullien & Calvet, 1903) and E. similis Ramalho, Rodríguez-Aporta & Gofas, 2022 (see below), suggests that this feature may have a taxonomic value. These heteromorphs allow filling empty surfaces unsuitable to the growth of autozooids and thus ensure colony continuity between lobes ( Cheetham & Cook 1983), such as in areas where irregularities in the substratum lead to a disrupted autozooid arrangement ( Hayward & Ryland 1999). Such kenozooids are observed in several cheilostome taxa such as Cribrilinidae Hincks, 1879 (e.g. Harmelin 1978), Setosella Hincks, 1877 ( Rosso et al. 2020) and Microporella Hincks, 1877 ( Di Martino & Rosso 2021).

HABITAT DISTRIBUTION

The present material assigned to H. neatonensis n. sp. came in most cases from coastal shelf habitats,particularly detritic biogenic bottoms often including empty shells and/or algal concretions ( Rosso 1989; 1996a; Chimenz Gusso et al. 2014 – recorded as H. multispinata ), hosting the Coastal Detritic Biocoenosis and the Shelf-edge Detritic Biocoenosis ( Pérès & Picard 1964; Pérès 1967). In the Gulf of Noto, the species was usually very rare, except in station PS 81-9D where several colonies encrusted small (1-2 cm), exceptionally larger, rhodoliths. The only colony from the Adriatic Sea (see below) was collected in a Coralligenous rocky bottom. Considering the sampling depths (27-120 m) and the sheltered position of colonies on the substrata, this species can be categorized as sciaphilic.

GEOGRAPHICAL DISTRIBUTION

Hemicyclopora neatonensis n. sp. has been collected in the Ionian Sea ( Rosso 1989; 1996a, b), in the southern Adriatic Sea off Apulia ( Chimenz & Faraglia 1995), and in the Tyrrhenian Sea off the Pontine Isles ( Chimenz Gusso et al. 2014) ( Table 4 ). However, it is likely that this species is more evenly distributed in the Mediterranean and that the present gaps are mainly due to the small colony size and the poor accessibility of local populations.

GEOLOGICAL DISTRIBUTION

Hemicyclopora neatonensis n. sp. also occurs in Early Pleistocene deposits of W Sicily ( Belice section) ( Di Geronimo et al. 1994; Rosso & Sanfilippo 2005), pointing to its persistence in this area.

Figures

FIG. 2. — Hemicyclopora neatoniensis n. sp.: A-C, general aspect of the colony with ovicellate and non-ovicellate autozooids and rare interspersed kenozooids. Note the variability in the size and shape of autozooids and in the nature of the ovicells; D, close-up of some zooids with the typical peristomes; E, non-ovicellate autozooids; F, an ovicellate autozooids with four oral spines. Origin: A-F, holotype, PMC. B34.1.4.2021a; Sicily, Gulf of Noto, 78 m; E, paratype, MNHN- IB-20174-769, Gulf of Noto, 45 m. Scale bars: A, C, 1 mm; B, D, 500 µm; E, F, 200 µm.

FIG. 3. — Hemicyclopora neatoniensis n. sp.: A, cluster of autozooids, several with ovicells associated with distal zooids smaller or developing teratologic morphologies; B, ovicell complex formed by a maternal autozooid and a distal kenozooid; C, ovicellate zooid with a very broad ovicell associated with a distal nonovicellate zooid. Note the dimorphic orifices with eight, occasionally seven spines, and the condyles morphology; D, contiguous autozooids with fused ovicells; E, polygonal porous kenozooid at the colony periphery; F, ancestrula with three daughter zooids exposing their basal pore chambers;Origin: Sicily,Gulf of Noto; A-E, PMC. B34.1.4.2021b2; F, PMC. B34.1.4.2021b1. Scale bars: 500 µm.

FIG. 10. — Distal part of ovicellate and non-ovicellate zooids, and ancestrulae,all at the same scale: A-C, Hemicyclopora neatonensis n. sp.; D-F, H. hexaspinae n. sp.; G- I, Escharella similis Ramalho, Rodríguez-Aporta & Gofas, 2022. Drawings from SEM pictures and examination under stereomicroscope. Origin: A-C, Sicily; D-F, Provence; G-I, Alboran Sea. Scale bar: 200 µm.