Galliconularia azaisi ( Thoral, 1935 ) Iten & Lefebvre, 2020

Iten, Heyo Van & Lefebvre, Bertrand, 2020, Conulariids from the Lower Ordovician of the southern Montagne Noire, France, Acta Palaeontologica Polonica 65 (3), pp. 629-639 : 634-636

Galliconularia azaisi ( Thoral, 1935) comb. nov.

Fig. 4.

1912 Conularia nova sp.; Miquel 1912: 20. 1935 Conularia azaisi Thoral, 1935 ; Thoral 1935: 159, pl. 11: 7–9,

pl. 15: 11a, b. not 1966 Eoconularia ? cf. azaisi ( Thoral, 1935) ; Dean 1966: 271. 1978 Eoconularia azaisi ( Thoral, 1935) ; Capéra et al. 1978: 73. not 1978 Eoconularia cf. azaisi ( Thoral, 1935) ; Capéra et al. 1978: 75. 2001 Eoconularia azaisi ( Thoral, 1935) ; Vizcaïno et al. 2001: 219,

fig. 3. not 2001 Eoconularia cf. azaisi ( Thoral, 1935) ; Vizcaïno et al. 2001:

219, fig. 3. not 2001 Eoconularia azaisi ( Thoral, 1935) ; Álvaro et al. 2001: 228. 2004 Eoconularia azaisi ( Thoral, 1935) ; Van Iten and Vhylasová 2004:

122. 2003 Paraconularia azaisi ( Thoral, 1935) ; Leme et al. 2003: 270,

fig. 5. 2016 Conularia azaisi Thoral, 1935 ; Van Iten et al. 2016b: 171, table 1. not 2016 Conularia cf. azaisi Thoral, 1935 ; Van Iten et al. 2016b: 171,

table 1. Type material: Thoral’s (1935) four syntypes: UM.ACI.416 ( Thoral 1935: pl. 15: 11a, b), UM.ACI.645 ( Thoral 1935: pl. 11: 7), UM.ACI.646 ( Thoral 1935: pl. 11: 9), and UM.ACI.647 ( Thoral 1935: pl. 11: 8). A specimen deposited in the palaeontological collections of western Brittany, Brest, France (LPB 10777) was erroneously mentioned as the holotype of Eoconularia azaisi by Álvaro et al. (2001). This specimen is instead a bivalve ( Eopteria crassa [ Thoral, 1935]) from the Lower Ordovician of the Montagne Noire (Muriel Vidal, personal communication 2018). Type locality: Saint-Chinian, Hérault, France. Type horizon: Euloma filacovi Trilobite Zone, Saint-Chinian Formation , upper Tremadocian, Lower Ordovician.

Material.— 28 specimens: UM.ACI.654–656 and 658; UCBL-FSL 133604–133610 , 712799 , and 713214–713229; from Lower Ordovician of Montagne Noire , France, for details see Appendix 1 .

Diagnosis.—Raised facial midline marked by a low, rounded (transversely), continuous external ridge. Exterior-most lamellae of the faces exhibit very fine, adaperturally gently arching, trochoidal (longitudinally) transverse ribs bearing submicroscopic, circular to sub-circular nodes; transverse ribs cross the midline ridge without interruption or diminution, terminating or greatly diminished in height in the narrow corner sulcus. Exterior-most lamellae of the interspaces exhibit very slender interspace ridges that terminate at their apertural end in a node. Deeper lamellae exhibit fine longitudinal ridges or grooves.

Description.—Specimens incomplete, variably deformed and exfoliated, with the largest specimen measuring approximately 58 mm in length; apex unknown, schott (apical wall) not observed, apertural margin gently arcuate but without evidence of inward folding (apertural lappets). Transverse cross section slightly rectangular; corners and facial midline un-thickened and lacking internal carina(e). Angle of divergence of the corners bounding a given face ranges from approximately 10–50°. Corners sulcate; corner sulcus narrow (Fig. 4A 1, C). Periderm along the facial midline outwardly folded to form a low, rounded (transversely), continuous ridge that is wider than the corner sulcus (Fig. 4A, C–E). On the faces, the exterior-most lamellae exhibit very fine, gently arched (adaperturally), trochoidal (longitudinally) transverse ribs, 2–11 per mm, which parallel the apertural margin; in two specimens, the transverse ribs exhibit closely spaced, sub-microscopic nodes (approximately 14–18 per mm; Fig. 4A 2); transverse ribs cross the midline ridge without interruption or diminution (Fig. 4A 2), terminating or greatly diminished in height in the corner sulcus. Interspaces wider than the transverse ribs, in the two node-bearing specimens exhibiting very slender interspace ridges that extend from a node on the transverse rib nearest the aperture to the gap between two nodes on the transverse rib nearest the apex (Fig. 4A 2). Faces of many specimens exhibit coarse, irregular folds and/or broadly sinusoidal, gently arched transverse folds that may be artifacts of deformation (Fig. 4C, D). Transverse ribs may be scalloped or jagged, especially in completely flattened specimens preserved in shale (Fig. 4E). Many specimens show multiple fine, commonly discontinuous, longitudinal folds or grooves (“filets”; Thoral 1935: 160) that number about 2 per mm (transversely) and along which the transverse ribs may be recurved adapically.

Remarks.—The foregoing description is based on Thoral’s (1935) original material (total of 12 specimens) plus 20 ad-

Fig. 4. Conulariid scyphozoan Galliconularia azaisi ( Thoral, 1935) , Saint Chinian and La Maurerie formations, upper Tremadocian–lower Floian, Lower → Ordovician; southern Montagne Noire, France. Specimens oriented with the apertural end directed toward the top of the page. A. The exterior surface of single face of a relatively large specimen, parts of which preserve the sub-microscopic nodes and interspace ridges (UCBL-FSL 713229; midline ridge indicated by the arrow) (A 1). Detail of the apertural region, showing some of the sub-microscopic nodes and interspace ridges, which cross the broad midline ridge (central part of the photograph) without diminution or disruption (A 2). B. Close-up view of the central portion of a single face (corners bounding the face missing) (UM.ACI.645), showing at least six discontinuous, narrow longitudinal folds and furrows (arrows). C. Overall view of the external surface of the single fully exposed face and bounding corners of one the most complete specimens, which is preserved in a siliceous concretion UCBL-FSL 712799A; midline ridge indicated by the white arrow, corner sulcus by the black arrow). D. View of the counterpart of the specimen in D UCBL-FSL 712799B; midline ridge indicated by the arrow). E. View of the exterior surface of part of a single face of a flattened specimen, the very fine transverse ribs of which are slightly wavy (scalloped) owing, probably, to tectonic shearing and deformation (UM.ACI.646; midline ridge indicated by the arrow; specimen also figured in Thoral 1935: pl. 11: 9). Scale bars: A 1, C, D, E, 10 mm; A 2, B, 0.1 mm.

ditional specimens. Though longer and more complete than that of Thoral (1935), the present description is generally in close agreement with equivalent portions of Thoral’s (1935) text. The most significant difference between the two descriptions is that Thoral (1935) did not note the presence of minute nodes and interspace ridges. Such features appear to be absent in Thoral’s (1935) material (e.g., Fig. 4C, D), but they are present in at least two of the additional specimens UCBL-FSL 713215 and 713229) examined by the present authors. In all other respects, the node-bearing specimens are similar to those examined by Thoral (1935), exhibiting for example the same broadly rounded midline ridge and thread-like transverse ribs which cross the midline ridge without diminution or disruption.

As is true for many other conulariids, the appearance of a given specimen of G. azaisi depends in part on the depth or level within the finely lamellar periderm at which the specimen is being examined. This in turn depends on the preservation of the periderm (whether complete or exfoliated) as well as on whether the periderm was split along one or more internal lamellae during extraction from the host rock matrix. The very fine, nodose transverse ribs and interspace ridges appear to be restricted to the outermost lamellae, which in many specimens are either missing (owing, we believe, to exfoliation) or covered by rock matrix, which can only be removed through mechanical preparation which may destroy delicate external surface features). The fine longitudinal ridges or furrows, which are similar to and possible homologous with those which occur within the periderm of many specimens of Archaeoconularia (see e.g., Bouček 1928: pl. 1: 17), occur in lamellae beneath those bearing the very fine transverse ornament and interspace ridges. In short, then, we do not believe that the two node-bearing specimens and the more numerous specimens that do not exhibit nodes should be assigned to separate species in the new genus. However, if future discoveries should prove this conclusion to be incorrect, then the diagnosis of Galliconularia will have to be emended accordingly.

Another factor affecting the appearance of specimens of G. azaisi is tectonic deformation, more specifically shearing of flattened specimens preserved in shale (Fig. 4E). In addition to being strongly compressed, such specimens differ from more or less three-dimensional specimens preserved in siliceous nodules in having the transverse ribs scalloped or jagged. But even in specimens preserved in siliceous nodules, deformation expressed as very fine wrinkling of the periderm may be present in the interspaces (Fig. 4A 2).

Subsequent to the publication of Thoral’s (1935) description, Vizcaïno et al. (2001) listed G. azaisi as Eoconularia azaisi . This assignment apparently was based on the presence in certain specimens of relatively coarse, sinusoidal transverse folds that follow the course of the very fine, adaperturally arching transverse ribs. Such folds resemble the sinusoidal transverse ribs of species such as Eoconularia amoena Sinclair, 1944 and Eoconularia loculata ( Wiman, 1895) . However, because most specimens of G. azaisi are deformed, we are inclined to agree with Thoral’s (1935) suggestion that the transverse folds in this conulariid are artifacts of directed stress sustained after final burial. In this connection it should be noted that Thoral (1935: 160) grouped the 12 specimens of G. azaisi he examined in two “distinct series”. The first series consisted of specimens having broad faces, large apical angles, poorly defined transverse ribs, and numerous, clearly defined, narrow longitudinal furrows or ridges (“filets”). Thoral did not list the registration numbers of these specimens. The second series consisted of larger and narrower specimens, again unspecified, that were further characterized by well-defined transverse ribs but only a few, widely spaced and discontinuous longitudinal lines. Thoral (1935) provisionally interpreted his two series as consisting, respectively, of the apical (first series) and more distal regions (second series) of an originally more elongate periderm having high apical angles in the apical region and much lower apical angles closer to the apertural end of the periderm. Owing to distortion and incomplete preservation of the faces, we think that determination of apical angles in G. azaisi is more difficult than implied by Thoral (1935); however, at this point we cannot rule out his hypothesis that the two series represent different portions of the periderm of a single species.

Stratigraphic and geographic range.—Late Tremadocian Saint Chinian Formation and early Floian La Maurerie Formation, Lower Ordovician of the southern Montagne Noire, France. See Appendix for detailed geographic and stratigraphic information on each specimen.