Escharella massiliana, Gray, 1848

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 : 389-391

“ Escharella ” massiliana n. sp.

( Fig. 8 A-G; Tables 1 ; 3 ; 4 )

urn:lsid:zoobank.org:act:285DA939-D492-47B3-893D-2BE808455973

Hemicyclopora multispinata – Harmelin 1976: 230 (table 3).

Escharella octodentata – Madurell et al. 2013: 126 (table 2).

TYPE LOCALITY. — Marseille, Planier Canyon, Mediterranean Sea.

TYPE MATERIAL. — Holotype. Mediterranean – France • 1 ovicellate colony, coated for SEM examination, c. 38 autozooids (16 ovicells); JGH-Stn 72.15; Marseille, Planier Canyon ; 43°07’20”N, 5°12’51”E; 115 m depth; 18.IV.1972; on empty shell; Dre; JGH leg.; MNHN-IB-2017-774 .

Paratype. Mediterranean – France • 1 small ovicellate colony; Corsica, off Calvi; R / V Catherine Laurence ; Bracors-3, Stn CL 74-84; 42°47’32”N, 9°08’17”E; 110-150 m depth; VII.1984; on biogenic debris; Dre; Fredj & Di Geronimo leg.; PMC. B36; 5.5.2021 .

OTHER MATERIAL EXAMINED. — Mediterranean – France • 1 small, dead colony; JGH-Stn 72.15; same data as holotype; MNHN • 2 colonies; Marseille-Cassis , Cassidaigne Canyon, JGH-Stn 72.9; 43°08’53”N, 5°25’55”E; 115-130 m depth; 22. III.1972; Dre; JGH leg.; MNHN • 1 small colony; Marseille-Cassis , Cassidaigne Canyon; 130 m depth; 19.IV.1971; on leather debris; Dre; H. Zibrowius leg.; MNHN .

Spain • 1 ovicellate colony; Catalonia, off Cap de Creus; INDEMARES 1 , Stn 12; 42°21’36.0”N, 3°19’37.2”E; 148 m depth; 23.IX.2009; detrital sand; 2 SEM photos, T. Madurell & M. Zabala leg.; MNHN .

ETYMOLOGY. — From Massilia, ancient Latin name of Marseille.

DIAGNOSIS. — Autozooids separated by deep grooves, frontal shield convex with slightly hummocky surface, marginal pores large. Distal and lateral walls subvertical. Orifice terminal, slightly longer than wide, proximal edge a flat, thick, parabolic convexity, bearing a small bump on the inner side, condyles indistinct, very short and blunt. Oral spines eight in both ovicellate and non-ovicellate zooids. Ovicells not closed by operculum, attached to distal wall of maternal zooid, kenozooidal; endooecium without proximal prominence, with similar surface relief as frontal shield. Ancestrula with opesia, cryptocyst and gymnocyst equally extended, ten spines (5 + 5).

DESCRIPTION

Colony encrusting, unilaminar, small. Autozooids elongated (L/W ratio = 1.56), oval to pentagonal, distinctly separated by deep grooves, laid out in quincunx; frontal shield uniformly convex except for the proximal raising end, smooth, slightly mamillated; marginal pores large (20-40 µm) in a single row + 1-2 in an upper position below the proximal edge of orifice. Distal wall vertical ( Fig. 8 ). Orifice distal, as long as wide, or slightly longer; internal arch wide, with indistinct short and blunt condyles at proximal ends ( Fig. 8A, F ); proximal edge clearly convex, with rounded (parabolic) tip, very thick with a square rim covered by a gymnocystal layer, uniformly flat on the upper side and with a small hump on the inner side. Oral spines eight in ovicellate and non-ovicellate zooids, articulated on thick, prominent bases, the proximalmost pair clearly convergent ( Fig. 8 A-C), the distalmost resting against the ovicell. Ovicells frequent (42% of zooids in the holotype), globular, acleithral, attached to the vertical distal wall of the maternal zooid, associated to a basal ooecium-producing kenozooid, frequently at the colony margin or inserted between two distal autozooids, with some marginal pores visible at the base of the endooecium and 2-3 pore-chambers below them belonging to the kenozooidal base; surface topography of the endooecium similar to that of the frontal shield; well calcified floor visible in ovicell under construction ( Fig. 8 A-C, G). Ancestrula with 10 spines, i.e., five spines around both the opesia and the cryptocyst (one case observed, Fig. 8D ).

REMARKS

Morphological features and taxonomic issues

This species shares many morphological features with E. similis , but differs from it essentially in the structure of the orifice. In “E.” massiliana n. sp. the proximal edge of the orifice is also typically convex, but with a square rim, uniformly thick and flat, without an umbo on the upper side, but with a very low protuberance on the inner side, only visible with SEM ( Fig. 8A, E, F ). This tiny bump may be considered as a primary lyrula, characterizing an intermediate stage between the genera Escharella and Hemicyclopora . This species was thus doubtfully placed in Escharella . The average length and width of autozooids, and the range of these dimensions ( Table 1 ) are smaller in “E.” massiliana n. sp. than in E. similis and the L/W ratio is higher, i.e., autozooids are more elongate. However, this comparison is based on few data. The number of ancestrular spines around the opesia is also different (five vs eight in E. similis ).

HABITAT DISTRIBUTION

The six examined colonies encrusted biogenic debris in four stations with similar habitat traits: detrital soft bottoms within the same depth range (110-150 m).

GEOGRAPHICAL DISTRIBUTION

The present records of “E.” massiliana n. sp. only concern two areas in the north-western Mediterranean: Marseille (Provence) and Calvi ( Corsica).

Figures

FIG. 8. — “Escharella” massiliana n. sp.: A, zooids of the colony edge with hummocky frontal shield and three terminal, recumbent ovicells; B, lateral view of an ovicellate zooid, note the small basal kenozooid and the large marginal pores; C, E, F, G, edge of the same colony as A, with different stages in the ovicell construction involving a small basal kenozooid, note the thickness of the proximal edge of the orifice; D, ancestrula and periancestrular zooids. Origin: A, C, E-G, Marseille, Planier canyon,holotype MNHN-IB-2017-774; B, D, Calvi, paratype PMC. B36. 5.5.2021. Scale bars: A, B, C, D, 200 µm; E, F, 50 µm; G, 100 µm.