Collarina sp.

(Fig. 14; Table 1)

? Collarina balzaci – Hayward 1974 (in part): 399, table 3.

MATERIAL EXAMINED. — France. Corsica, Île-Rousse islets., 42°38’42”N, 8°56’04”E, 5 m, 9.IV.1978, coll. by H. Zibrowius, 8 small colonies on 2 small pebbles (together with 1 colony of C. denticulata), MNHN-IB-2014 -1928. — Corsica, Calvi, Stareso, 42°34’48”N, 8°43’28.60”E, 3 m, IX.1980, coll. by JGH, 2 small colonies on pebble, MNHN-IB-2014 -1929. — Corsica, Stareso, 42°34’49”N, 8°43’28”E, 7 m, 26.VIII.2018, coll. by JGH, 1 colony on small pebble, MNHN . — Corsica, Scandola, Gargallo, 42°21’58”N, 8°32’26”E, 7 m, 27.VIII.2018, coll. by JGH, 2 colonies (one fertile) on small pebbles, together with C. denticulata, MNHN . — Greece. Chios, P. J. Hayward leg., 1 colony on pebble ( Photos MSJ), NHMUK 1975. 1. 12. 419 .

DESCRIPTION

Colony encrusting, pluriserial, unilaminar, medium-sized in available material. Autozooids roughly oval with marginal gymnocyst generally poorly visible in frontal view except at proximal edge (Fig. 14A, B). Costate shield moderately convex; costae smooth, 9-11 in most cases, with a large pelma at the top of the ascending base, the latter with a rounded outline, often a smaller pelma in inner position; intercostal lacunae 2-4 between adjacent costae, rounded (Fig. 14B). Apertural bar more or less triangular, with distal side broad, concave, sloping towards the proximal edge of orifice; a pair of pelmatidia near the tip of the bar and a pair of pelmata laterally at the base of the proximal side (Fig. 14C). Adventitious avicu- laria 2 in majority of autozooids, directed laterally, proximal membranous area relatively large and rounded. Autozooidal orifice clearly wider than long, with maximum width at the proximal corners, the latter in the form of broad square indentations; proximal edge straight and somewhat resembling a lyrula (Fig. 14C). Oral spines relatively thin, 3-5 (3-4 in most zooids), 2 in ovicelled zooids. Ooecium with moderate relief, formed by distal kenozooid. Ancestrula cribrimorph with few costae and 7 spines (specimen from Île-Rousse: Fig. 14D) or 9 spines (fertile specimen from Gargallo).

REMARKS

The available specimens present several morphological features that suggest some relationship with C. speluncola Harmelin, n. sp., i.e. the smooth aspect of the costate shield and more particularly the shape of the orifice with the proximal corners cut by a broad indentation and the same number of thin oral spines. The main features differentiating Collarina sp. from C. speluncola Harmelin, n. sp. are the more pronounced lateral indentations of the orifice, the more raised and straighter proximal edge of the orifice, autozooids with narrower lateral gymnocyst, costate shield with fewer costae and lacunae, and ovicell with ectooecium less smooth. The number of spines of the ancestrula was curiously variable in the available material, but close to that of C. speluncola Harmelin, n. sp. (seven or nine vs height). Two specimens in poor condition (Monaco, 18.X.1997 and Stareso, 26.VIII.2018) encrusting small pebbles with characters apparently intermediate between Collarina sp. and C. speluncola Harmelin, n. sp. could not be placed with certainty in either of the two taxa. One specimen on a small pebble from the Aegean Sea (Chios: NHMUK 1975.1.12. 419), ascribed to C. balzaci by Hayward (1974), presents the same type of orifice and costate shield. The divergence of this specimen from the typical features of C. balzaci had already been noticed by Bishop (1988), who considered that it may be an unnamed species of Collarina . The question whether Collarina sp. and C. speluncola Harmelin, n. sp. are distinct species or two conspecific ecotypes induced by very different habitat conditions remains open pending more abundant further material.

HABITAT AND GEOGRAPHICAL DISTRIBUTION

The specimens from Corsica were found in three shallow-water sites on the west coast (3-7 m), encrusting small pebbles collected among boulders. In these sites, Collarina sp. occurred with C. denticulata Harmelin, n. sp. on the few sampled pebbles. The specimen from Chios was collected in the same type of habitat. Knowledge of the geographical distribution of Collarina sp. is poor; its records include Corsica, Chios and, possibly, Monaco.