Idmidronea coerula Harmelin, 1976: 185

HAYWARD, PETER J. & McKINNEY, FRANK K., 2002, Northern Adriatic Bryozoa From The Vicinity Of Rovinj, Croatia, Bulletin of the American Museum of Natural History 2002 (270), pp. 1-139 : 107-110

Idmidronea coerula Harmelin, 1976: 185 .

DESCRIPTION (AMNH 1020; CMRR 2274): Erect, fan­shaped colonies of dichotomous branches that curve gently laterally or frontally. Colonies less compact and branches more robust than for Exidmonea atlantica . Branch cross section subtriangular, with flat abfrontal surface along which zooids originated and with keeled frontal surface. Distally convex growth lines on abfrontal surface reflect former positions of branch tips. Peristomes of zooids arranged in well­developed to ragged transverse fascicles, each located within one half of the frontal surface. Complete rows consist of usually four, locally five, peristomes, with distal tips isolated and bent in various directions. Locally, autozooidal rows less well defined, with fascicles of three or two peristomes, and less commonly individual peristomes completely independent of others in their row. Fascicles typically curved proximally near the lateral branch margin. Most peristomes curved, bent away from branch midline. Proximal portions of autozooids and their peristomes longest for zooids along the central keel and shortest for those along lateral edge of branch. Individual peristomes may alternately expand or contract, and their diameters are less constant than are those in E. atlantica . Peristome and aperture diameters decreased slightly toward the abfrontal surface.

REMARKS: Harmelin (1976) reported typically five to six peristomes per fascicle, with a range from three to eight in the original specimens that he collected from the Mediterranean near Marseilles. No gonozooids were found in the Adriatic specimens examined, but Harmelin’s (1976) specimens had frontally centered, elongate gonozooids, with inflated brood chambers that extended across three to five fascicles of zooids. Brood chambers most commonly are situated immediately proximal to branch bifurcations, though some extend from the parent branch onto the proximal portions of both descendant branches. Ooeciopores are located at about midlength of brood chambers, on the distal side of an autozooidal peristome, at the end of short, recurved, transversely compressed ooeciostome. The outer side of each recurved ooeciostome is prolonged as a short hood partially occluding the ooeciopore.

DISTRIBUTION: The species is previously known only from the Mediterranean.

MEASUREMENTS (SKELETAL): AD 126 ± 9 µm, 110–140 (2, 20), PD 144 ± 9, 130–160 (2, 20), ASW 270 ± 51, 180–400 (2, 20), RS 515 ± 46, 440–600 (2, 20), BW 635 ± 85, 480–780 (2, 20).

FAMILY ANNECTOCYMIDAE

HAYWARD AND RYLAND, 1985b

GENUS ANNECTOCYMA

HAYWARD AND RYLAND, 1985b

Annectocyma arcuata ( Harmelin, 1976) Figure 51A–D

Diaperoecia arcuata Harmelin, 1976: 89 . Zabala, 1986: 620. Annectocyma arcuata: Zabala and Maluquer, 1988: 167 .

DESCRIPTION (AMNH 1021–1023): Colonies of undivided erect branches up to at

least 4 mm long, narrow at base and broadening upwards, from 0.5 mm basally to 1 mm width at top. Individual branches gently arched, with distinct peristome­bearing convex frontal and zooid­barren concave abfrontal surfaces. Autozooidal peristomes with small diameter, distributed in regular quincuncical pattern over frontal surface. Brood chambers inflated, located distally in region of maximum branch width, occupying over half the branch width. Ooeciostomes more or less centrally placed in brood chamber with smaller diameter basally than peristomes of autozooids, then compressed into transversely elongated aperture with transverse length greater than peristomial diameter of autozooids. Several autozooidal peristomes penetrate brood chambers.

REMARKS: Colony morphology and zooidal measures of the Adriatic specimen correspond exactly with attributes determined by Harmelin (1976). All Harmelin’s specimens were individual branches, as is the Adriatic specimen. However, the Adriatic specimen arises from a short section of a proximally broken adnate portion, leaving open the possibility that more than one branch arose from a linearly extended encrusting base.

DISTRIBUTION: This species is previously known from Sicily and the coast of Provence. Harmelin (1976) reported the species at depths of 60 to 150 m, growing on shells of dead molluscs on the coralligenous sea floor.

MEASUREMENTS (SKELETAL): AD 141 ± 7 µm, 133–150 (1, 10), PD 167 ± 23, 137– 200 (1, 10), AS 343 ± 40, 283–417 (1, 10), GL 595 ± 21, 583–620 (1, 3), GW 417 (1, 1).

Annectocyma cf. A. major ( Johnston, 1847) Figure 51E, F

Alecto major Johnston, 1847: 281 .

Stomatopora major: Hincks, 1880: 427 .

Diaperoecia major: Harmelin, 1976: 79 . Zabala, 1986: 623.

Annectocyma major: Hayward and Ryland, 1985b: 1077 . Zabala and Maluquer, 1988: 167. Entalophora proboscidea: Calvet, 1931: 33 .

DESCRIPTION (AMNH 1024): Colony erect, single, gradually widening, arched branch with incomplete terminal brood chamber. Autozooids with moderately short, gradually divergent peristomes, with curvature increasing away from branch surface. Autozooidal aperture diameters and spacing relatively large. Brood chamber widening distally, incorporating bases of several autozooecial peristomes; ooeciostome not formed.

REMARKS: The single specimen has the same growth habit as Annectocyma arcuata . However, the autozooids and autozooidal spacing are distinctly larger and fall within the lower range of sizes of A. major as given by Harmelin (1976), which is greater than that for any of the other Mediterranean species of Annectocyma . Having only one specimen and in the absence of information on the ooeciostome, we are reluctant firmly to assign the specimen to A. major .

MEASUREMENTS (SKELETAL): AD 165 ± 10 µm, 150–180 (1, 10), AS 506 ± 86, 400– 640 (1, 10).

Annectocyma sp. Figure 51G–I

DESCRIPTION (AMNH 1025, 1026): Colonies encrusting, consisting of one or more lobe­shaped, multiserial branches. Firstformed encrusting branch extending in same direction as ancestrula or diverging obliquely. In two of the three specimens, a second branch budded obliquely back from first asexual zooid, extending opposite growth direction of ancestrula and primary branch. Additional encrusting branches in these two specimens originating adventitiously about midway along length of primary branch and extending perpendicularly from branch margin. No erect branches present in available specimens. Autozooids with small diameters but relatively widely spaced. Peristomes in available specimens relatively short. Ancestrulae short, with the protoecial disc (233 ± 15 µm, N = 3) almost three times diameter of the peristome (833 ± 6 µm, N = 3) extending from it.

REMARKS: The specimens are more delicate than either of the two other species of Annectocyma found in the vicinity of Rovinj and have a different growth habit, but we have not assigned them to a species because of a lack of information on gonozooids.

MEASUREMENTS (SKELETAL): AD 119 ± 12 µm, 100–140 (3, 22), AS 445 ± 68, 320– 560 (3, 22).

GENUS ENTALOPHOROECIA HARMELIN, 1976

Entalophoroecia deflexa ( Couch, 1844) Figure 52A–D

Figures

Fig. 51. A–D. Annectocyma arcuata. A. General aspect (AMNH 1021; 0.5 mm). B. Brood chamber (AMNH 1022; 0.5 mm). C. Autozooidal interior with small spines (AMNH 1023; 0.05 mm). D. Autozooidal peristome and orifice (bottom) and (center) ooeciostome with oval ooeciopore (AMNH 1022; 0.1 mm). E, F. Annectocyma cf. A. major (AMNH 1024). E. General aspect (0.5 mm). F. Incompletely formed brood chamber at branch tip (0.2 mm). G–I. Annectocyma sp. G. Colony origin with divergent branches and (bottom) lateral branch (AMNH 1025; 0.5 mm). H. Oblique view of colony origin (center) and (left) lateral branch with incipient brood chamber (AMNH 1026; 0.5 mm). I. Ancestrula and early autozooids (AMNH 1025; 0.1 mm).

Fig. 52. A–D. Entalophoroecia deflexa. A. General aspect (AMNH 1027; 1 mm). B. Ooeciostome (center) (AMNH 1027; 0.1 mm). C. Pseudopores (AMNH 1027; 0.02 mm). D. Ancestrula (bottom center and early autozooids on Cellaria branch (AMNH 1028; 0.5 mm). E–G. Entalophoroecia robusta (AMNH 1029). E. General aspect (0.5 mm). F. Branch tip (0.5 mm). G. Pseudopores, more abundant on branch surface (left) than on (right) peristome (0.05 mm).