Dimorphomicropora voigti Ducasse & Vigneaux, 1960

Taylor, Paul D. & Villier, Loïc, 2022, Cretaceous microporid cheilostome bryozoans from the Campanian historical stratotype of southwest France, Geodiversitas 44 (18), pp. 515-525 : 521-522

Dimorphomicropora voigti Ducasse & Vigneaux, 1960

( Fig. 3 )

MATERIAL. — Lectotype. UB C.B.993 ( Ducasse & Vigneaux 1960: fig. 1), probably Aubeterre Fm, Meschers, Charente-Maritime ( France) . — Paralectotype. UB C.B.994 ( Ducasse & Vigneaux 1960: fig. 2), probably Aubeterre Fm, Meschers, Charente-Maritime ( France) . — Other material: NHMUK PI BZ 8767, 8768, 8769, Aubeterre Fm, Pointe de Suzac, Meschers, Charente-Maritime ( France).

OCCURRENCE. — Upper Campanian, Aubeterre Formation.

DESCRIPTION

Colony erect, consisting of cylindrical branches, complete bifurcations not observed, probably articulated during life. Branches 8- to 10-serial, up to 2 mm in preserved length, normally 0.61-0.66 mm wide increasing to about 1 mm in diameter where fertile zooids are present. Colony base unknown. Autozooids longer than wide, ZL 444-489 μm (N colonies 1; N zooids 5; mean 458 μm; SD 20 μm), ZW 178-200 μm (N colonies 1; N zooids 5; mean 182 μm; SD 20 μm), elongate hexagonal. Frontal wall cryptocystal, margins raised, centre depressed, smooth textured; cryptocystal pores lacking; single pair of opesiules located proximolaterally of orifice within depressed central part of cryptocyst, longitudinally elliptical. Orifice dummy shaped, longer than wide, OL 118-141 μm (N colonies 2; N zooids 8; mean 132 μm; SD 8 μm), OW 70-94 μm (N colonies 2; N zooids 8; mean 87μm; SD 10 μm), divided into a broad, rounded quadrate distal part and a narrow, long, tonguelike proximal prolongation, each with a salient rim. Fertile autozooids clustered, ooecia helmet shaped, slightly wider than long, about 200-220 µm long by 240-300 µm wide, calcification smooth, continuous with the cryptocyst of the distal zooid, orifice of ovicellate zooids round, larger than those of non-ovicellate zooids, about 200 µm in diameter. Mandibulate polymorphs sporadically distributed, larger than autozooids, 550-590 µm long by 260-290 µm wide, frontal wall and opesiules similar to those of the autozooids, orifice semielliptical with a slight proximal lip, longer than wide, about 290 µm long by 210-240 µm wide.

REMARKS

The presence of mandibulate polymorphs and the dummy shaped orifices serve to distinguish D. voigti from D. crestulata (described below) and also from the Maastrichtian species D. rugica .

Figures

FIG. 3. — Dimorphomicropora voigti Ducasse & Vigneaux,1960: A, lectotype, UB C.B.993 (Ducasse & Vigneaux 1960: fig. 1), probably Aubeterre Fm, Meschers, Charente-Maritime, branch with large polymorphic zooid near base; B, E, F, NHMUK PI BZ 8767, Aubeterre Fm, Pointe de Suzac, Meschers; B, branch; E, autozooids near base of branch; F, detail of an orifice; C, G, NHMUK PI BZ 8768, Aubeterre Fm, Pointe de Suzac, Meschers; C, branch with a large polymorphic zooid near the centre; G, detail of polymorph; D, paralectotype, UB C.B.994 (Ducasse & Vigneaux 1960: fig. 2), probably Aubeterre Fm, Meschers, Charente- Maritime; H, NHMUK PI BZ 8769, Aubeterre Fm, Pointe de Suzac, Meschers, Charente-Maritime, dilated branch with a cluster of ovicellate zooids. Scale bars: A, B, C, D, H, 500 μm; E, 200 μm; F, G, 100 μm.