Collarina denticulata Harmelin, n. sp.

(Figs 6; 7C; 15D; 16E; 18C; Tables 1-3)

urn:lsid:zoobank.org:act: 2D62C756-80CF-4745-B5E3-6FC6EE64264D

TYPE LOCALITY. — France, Marseille, Frioul Is.

TYPE MATERIAL. — Holotype. France, Marseille, Frioul Is., quarantine port, 43°16’36”N, 5°18’18”E, 12 m, 26.II.1990, coll. by JGH, ovicelled colony on asbestos tile, MNHN-IB-2014-1916.

Paratypes. France. Marseille, Frioul Is., quarantine port, same origin and substrate as the holotype, 3 colonies + coated colony, MNHN-IB-2014-1917. — Marseille, Ratonneau Is., Croix headland, 43°17’12”N, 5°19’24”E, 5 m, 25.X.1978, coll. by JGH, 3 large colonies on underside of cobble, MNHN-IB-2014-1918. — Port-Cros, Bagaud Is., 43°00’56’’N, 6°21’37’’E, 7 m, IX.1985, coll. by JGH, 5 colonies on plastic debris, MNHN-IB-2014-1919 .

OTHER MATERIAL EXAMINED. — France. Gulf of Fos, Renaïre, 43°22’00”N, 5°00’27”E, 10 m, 25.VII.1994, coll. by JGH, 8 large colonies on biogenic flat stone, MNHN . — Côte Bleue, La Vesse, 43°20’29”N, 5°15’43”E, 6 m, 03.VII.1999, coll. by JGH, 3 colonies on Haliotis shell, MNHN . — Marseille, Frioul Is., quarantine port, 43°16’36”N, 5°18’18”E, 4 m, 28.I.1971, coll. by JGH, 5 colonies detached from glass debris + 3 colonies on tile, MNHN, NHMUK . — Marseille, Frioul Is., quarantine port, same origin and substrate as holotype and paratypes 3, 7 colonies, MNHN . — Marseille, Calanques Coast, Sormiou, Capellan, 43°12’20”N, 5°25’35”E, 18 m, 23.IV.1998, coll. by JGH, 2 colonies on pebble and plastic debris, MNHN . — Marseille, Calanques Coast, Sormiou, Figuier Cave, 43°12’26”N, 5°12’26”E, 19 m, VII.2000, coll. by JGH, 2 colonies on experimental substrate (one year colonization), MNHN . — Cassis, Trémies, 43°11’60”N, 5°30’44”E, 15 m, VII.1987, coll. by JGH, 2 colonies on pebble, MNHN . — Cassis, Port-Miou, 43°12’11”N, 5°30’53”E, 18 m, 23.II.1971, coll. by JGH, 17 colonies on underside of pottery, JGH-St. 71.3, MNHN . — Cassis, 43°12’22”N, 5°30’44”E, 18 m, 20.VIII.1975, 2 colonies on clay-pigeon target, JGH-St.75.2, MNHN . — Port-Cros, Bagaud Is., same site as paratype 2, 7 m, VII.1985, coll. by JGH, 1 colony on pebble + 1 coated colony, MNHN, NHMUK . — Corsica, Île-Rousse Is., 42°38’42”N, 8°56’04”E, 5 m, 09.IV.1978, 1 colony on a pebble together with Collarina sp., MNHN — Corsica, Scandola, Imbutu, 42°22’26”N 8°33’06”E, 6 m, 24.VIII.2018, coll. by JGH, 5 colonies on small pebbles, MNHN, NHMUK . — Corsica, Stareso, 42°34’49”N, 8°43’28”E, 7 m, 26.VIII.2018, coll. by JGH, 4 colonies on small pebbles together with Collarina sp., MNHN . — Corsica, Scandola, Elpa Nera, 42°24’21”N, 8°36’30”E, 7 m, 27.VIII.2018, coll. by JGH, 5 colonies on pebbles in Posidonia bed, MNHN, NHMUK . — Corsica, Scandola, Gargallo, 42°21’58”N, 8°32’26”E, 7 m, 27.VIII.2018, coll. by JGH, 25 colonies on small pebbles together with Collarina sp., MNHN . — Corsica, Scandola, Elbu, 42°22’19”N, 8°33’21”E, 10 m, 30.VIII.2018, coll. by JGH, 4 colonies on pebbles in a cave, together with C. gautieri Harmelin, n. sp., MNHN . — Corsica, Scandola, Cala di l’Oru, 22 m, 31.VIII.2018, coll. by JGH, 2 colonies on stones together with C. gautieri Harmelin, n. sp., MNHN .

Spain. Catalonia, L’Estartit, Medes Islands, 42°14’53.102”N, 03°7’52.183”E, 9 m, 07.V.2015, coll. by TM-MZ, 1 colony on Pinna nobilis Linnaeus, 1758, MZB.

ETYMOLOGY. — From Latin denticulatus: with denticles, in reference to the denticulate proximal edge of the orifice.

DIAGNOSIS. — Colonies eventually large-sized; autozooids with narrow marginal gymnocyst and moderately convex costate shield formed by 8-14 costae thickened when fusing at the midline; orifice as long as broad, with proximal edge convex and fringed with denticles; 3-4 oral spines; adventitious avicularia paired in most cases, with rostrum acute, directed laterally; ovicells endozooidal, acleithral, with a distinctive sclerite sealing the ooecial vesicle, ooecium formed by a distal autozooid, occasionally by a distal kenozooid; ancestrula with 6 spines (occasionally 5).

DESCRIPTION

Colony encrusting, unilaminar, multiserial, irregularly shaped, reaching large size (> 1000 autozooids). Autozooids roughly hexagonal with a rounded distal end, but appearing oval owing the shape of the costal shield. Gymnocyst narrow, little visible except at the zooid proximal corners. Costate shield relatively flat, oval to circular made up of 8-14 costae (predominantly 9, Table 2), their fusion in the midline forming a thickening that joins the apertural bar in highly calcified colonies (Fig. 6A, B). Costae irregularly broad, with smooth surface; a large, funnel-shaped pelma at the base of each costa and, nearer to the shield centre, 1-2 smaller pseudopores (pelmatidia) opening at the summit of a conical protuberance, occasionally alternating with a small pelma (Figs 6E, F; 7C). Intercostal lacunae rather small, generally transversally compressed and partially occluded by 1-2 small, blunt denticles rising from the inner edge (Fig. 6B, F). Apertural bar forming a thick, variably raised, triangular bulge with 2-3 pelmatidia at the tip and a pair of large pelmata on the proximo-lateral sides (Figs 6C, D; 7C). Adventitious avicularia always present, occurring on both sides of the apertural bar in most cases (88%), or single, directed laterally, relatively narrow, with acute, triangular mandible (Figs 6C, D; 7C), occasionally presenting nested cystids (Fig. 6G, see below). Orifice of non-ovicelled zooids as long as wide on average (Table 1); anter (distal frame of primary orifice) semicircular, with proximal ends forming smooth-edged, poorly prominent condyles; proximal edge (poster) convex and denticulate, with 5-7 small denticles and a thick knob overhanging the condyles at each corner (Figs 6C, D; 7C). Ovicelled orifice clearly broader, with proximal edge less convex, bearing 7-12 denticles (Figs 6B; 15D). Oral spines 3 (> 70%) or 4 in non-ovicelled zooids, 2 in ovicelled zooids; basal part thick and conical, whip part thin and long (Fig. 6C, D). Ovicell slightly prominent, endozooidal, acleithral, ooecial vesicle protected by a pseudo-operculum, i.e., a thick chitinous sclerite (Fig. 15D), ooecium formed by distal autozooid or, more rarely, by a distal kenozooid, broader than long (Figs 15D; 16E; Table 1), ectooecium with numerous pseudopores and relief variably pronounced according to calcification level. Ancestrula cribrimorph, orifice length a little less than one third the total length, predominantly 6 spines.

REMARKS

Collarina denticulata Harmelin, n. sp. is easily distinguished from the other Collarina species in having orifices with proximal edge clearly convex and serrate. Another obvious feature is the endozooidal nature of ovicells with the formation of the ooecium by a distal autozooid. These particular features, never noted in previous descriptions of specimens assignable to Collarina, make the differences with the other Collarina species indisputable.

HABITAT AND GEOGRAPHICAL DISTRIBUTION

The habitat range of C. denticulata Harmelin, n. sp. appears to be limited to the nearshore zone, at shallow depth (<25 m), in sites little affected by sedimentation, on undersides of rigid substrates, either natural (e.g. cobbles, empty shells) or artificial (e.g. pottery, plastic debris) (Fig. 18C). In five sites from Corsica (5-22 m, list above), colonies of C. denticulata Harmelin, n. sp. occurred on pebbles with Collarina sp. or C. gautieri Harmelin, n. sp. All examined specimens of C. denticulata Harmelin, n. sp. were collected in the NW Mediterranean (Provence, Catalonia, Corsica). It seems probable that this species is endemic to this region. It is unlikely to have been completely overlooked elsewhere, considering its distinctive morphology and its easily accessible habitat.