Adolfia cf. pseudomultifida (Vandercammen, 1955)

Mottequin, Bernard, 2008, New observations on Upper Devonian brachiopods from the Namur-Dinant Basin (Belgium), Geodiversitas 30 (3), pp. 455-537 : 497-501

Adolfia cf. pseudomultifida (Vandercammen, 1955) (Fig. 42)

Gürichella pseudomultifida Vandercammen, 1955: 2 , 3; 1957d: 15-24, 26-31, 47, pl. 1, figs 1-4, 5-8 (?), 9, 10, non 11, 12 (= A. biverrucosa ), 13, text-figs 4-23; 1966: 275, 284, pl. 3, fig. 9.

Guerichella pseudomultifida – Sartenaer 1967: 386.

TYPE SPECIES. — Spirifer deflexus Roemer, 1843 , by sub- MATERIAL EXAMINED. — BM-2002-8 (eight articulated sequent designation (Schuchert 1929: 27). specimens).

REMARKS REMARKS

The two types of micro-ornament observed in the These relatively small-sized specimens display the Devonian “Guerichellinae” from Belgium led Vander- following characters: widest at the posterior margin, cammen (1966: 266) to reserve the genus Adolfia for acute cardinal extremities, well-developed ventral

Mottequin B.

formations, may represent immature forms of A. pseudomultifida , but in the absence of specimens of comparable size to the holotype (IRScNB a7978), they are tentatively compared to this species.

Adolfia biverrucosa (Vandercammen, 1955) ( Figs 43 A-F; 44; Table 4)

Gürichella biverrucosa Vandercammen, 1955: 3 ; 1957d: 24, 25, 30-37, 47, pl. 1, figs 14-20, text-figs 24-39; 1966: 275, 284, pl. 3, fig. 8.

Gürichella pseudomultifida – Vandercammen 1957d (e.p.): pl. 1, figs 11, 12.

Guerichella biverrucosa – Sartenaer 1967: 386.

MATERIAL EXAMINED. — BM-2003-8 (nine articulated specimens, one ventral valve); Olloy 575 (10 articulated specimens, one ventral valve).

DESCRIPTION

Shell medium-sized, wider than long (width/length ratio: 1.35-1.53), dorsibiconvex to slightly ventribiconvex, rounded subpentagonal in outline; hinge line shorter than greatest width (hinge line width/

width ratio: 0.64-0.90); widest at about mid-length or posteriorly; anterolateral margins outlining a curve variably excavated by the sulcus in its median part; cardinal extremities rounded.

Ventral valve regularly curved in lateral profile except in beak area; flanks sloping moderately towards lateral commissure; sulcus wide (sulcus width/width ratio: 0.43-0.56), originating at beak, moderately deep, relatively well-delimited, with bottom flattened at anterior margin; tongue 1.22-1.62 times wider than high, subtrapezoidal to subrectangular,

perpendicular to commissural plane (in some speci-

FIG. 42. — Adolfia cf. pseudomultifida (Vandercammen, 1955) ,

mens, distal part of tongue bent dorsally); shoulder almost complete shell (IRScNB a12283),loc. BM-2002-8,Les Va- lines concave; shoulder and apical angles between lisettes Formation: A, ventral view; B, dorsal view; C, lateral view; 102-112° and 146-(146°+) respectively; interarea D, posterior view; E, anterior view; F, detail of micro-ornament. Scale bars: A-E, 10 mm; F, 1 mm. concave, high (interarea height/hinge line width ratio: 0.17-0.28), cata-apsacline; delthyrium wide,

closed by relatively convex pseudodeltidium. interarea, a relatively narrow sulcus, high tongue, Dorsal valve wider than long (width/dorsal valve 6-7 low and rounded costae per flank, separated length ratio: 1.32-1.53), subtrapezoidal in outline; by similar grooves. Micro-ornament composed of posterolateral areas tending to become flat; highest large spine bases aligned subradially. These speci- at front or about midvalve (in the second case, it mens, recovered in the Neuville and Les Valisettes curves progressively or maintains its height); fold

Upper Devonian brachiopods from Belgium originating at beak, moderately high, with top Flanks covered by at least nine rounded costae, rounded at anterior margin; interarea orthocline, separated by similar grooves; sulcus with a median plane, linear. costa and 1-3 additional costae;fold with 2or 3 costae;

Mottequin B.

micro-ornament consisting of subradial alignments Vandercammen [1957d: 31, 32, pl. 1, figs 19, 20]). composed of small and big spine bases principally on Ventral interior with extrasinal thin dental plates the top of costae;growth lamellae irregularly spaced(see supporting small and rounded teeth; delthyrial plate

Upper Devonian brachiopods from Belgium absent (or very short?); lateral and central apical cavities not filled in.

Dorsal interior with ctenophoridium including more or less 15 thickened plates (some with dichotomous distal extremities); dental sockets moderately deep; spiral cones not observed.

DISCUSSION

Adolfia biverrucosa differs from A. pseudomultifida by its less transverse outline, its narrower sulcus and by its micro-ornament including small and large spine bases.

DISTRIBUTION

Vandercammen (1957d: 34) reported Adolfia biverrucosa within “F2b”, “F2i” and “F2IIIb”. The specimens presently studied originate from the top of the

Neuville Formation in the railway section between Mariembourg and Nismes (BM-2003-8; southern border of the Dinant Synclinorium), i.e. the locus typicus of the species.

Figures

FIG. 43. — A-F, Adolfia biverrucosa (Vandercammen, 1955), almost complete shell (IRScNB a12285), loc. BM-2003-8, Neuville Formation; G-L, Adolfia sp., complete shell (IRScNB a12288), loc. BM-2002-7, Neuville Formation; A, G, ventral views; B, H, dorsal views; C, I, lateral views; D, J, posterior views; E, K, anterior views; F, L, detail of micro-ornament. Scale bars: A-E, G-K, 10 mm; F, L, 1 mm.