Haroella charcensis Bulot, Pictet, Frau & Bryers, 2024
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publication ID |
https://doi.org/10.1186/s13358-024-00343-4 |
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persistent identifier |
https://treatment.plazi.org/id/AC080812-3346-161D-3D64-948F8E09887E |
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treatment provided by |
Felipe |
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scientific name |
Haroella charcensis Bulot, Pictet, Frau & Bryers |
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Haroella charcensis Bulot, Pictet, Frau & Bryers in
Bryers et al. (2024)
Fig. 7A–E View Fig
? 2004. Lyticoceras nodosoplicatum (Kilian & Reboul) , Ettachfini, p. 147, pl. 20, fig. 5 (sol).
2022. Haroella gen. nov. in Bryers et al., appendix A, fig. S1 A.
2024. Haroella charcensis gen. nov. sp. nov. Bulot, Pictet, Frau & Bryers in Bryers et al., appendix A, Supplementary data, Multimedia component 11, fig. 10E
* 2024. Haroella charcensis gen. nov. sp. nov. Bulot, Pictet, Frau & Bryers in Bryers et al., appendix A, Supplementary data, Multimedia component 11, fig. 10A-D
Type specimens. Te holotype, specimen MGL .108840
( Figs. 7A–D View Fig ), is deposited in the Muséum cantonal des sciences naturelles at Lausanne, leg by Luc G. Bulot. A cast of the holotype is held in the reference collections of the North Africa Research Group at the University of Manchester (cat no NARG-MAN-C-212). It comes from Bed LCH 287 of Serre de l’Ane section ( Fig. 6 View Fig ), Drôme department, south-eastern France ( Fig. 1 View Fig ) .
Te specimen cat no MHNG GEPI 30234, Coll. F.-J. Pictet—Salève ( Figs. 1 View Fig and 7E View Fig ) of the Muséum d’histoire naturelle de Genève is considered to be a plesiotype that allows a better description of inner whorls. It comes from the Grande Varappe section at Mt. Salève, Haute-Savoie department, eastern France.
Diagnosis. Like for the genus.
Description. Te plesiotype MHNG GEPI 30234
( Fig. 7E View Fig ) is a small-sized phosphatic mould, green in colour because it is coated with glauconite. Te whorls are slightly overlapping. Te whorl section is subquadratepolygonate, slightly higher than wide (Wb/Wh = 0.87). Te venter is large, flattened and smooth. Te centre of the umbilicus is not preserved. Te whorls begin at 16 mm in diameter with an ornamentation consisting of radial to slightly prorsiradiate primary ribs arising in pairs from an umbilical bulla. Between each pair are three single, fine, intercalating ribs that originate from the umbilical wall and terminate at the ventro-lateral edge with a barely perceptible bulla. From a diameter of 30 mm in diameter, the anterior rib becomes thicker and bears a lateral tubercle situated in the upper two-thirds of the flank from which it branches. One of these secondary ribs is stronger and reaches a reinforced ventro-lateral tubercle, reminiscent of the ornamental style of Distoloceras hystrix sensu Neumayr and Uhlig (1881 , pl. XLVI, fig. 4). All ribs tend to incline forward on the upper third of the flank.
Te holotype MGL.108840 ( Fig. 7A–D View Fig ) is a moderately-sized limestone mould of light grey colour. It is subevolute (U/D = 0.36) with slightly overlapping whorls. Te umbilical shoulder forms a rounded corner and the umbilical wall is deep, vertical to slightly convex. Te conch is not preserved up to 5 mm in diameter. Te whorl section of the last whorl is subrectangular-polygonal, slightly higher than wide (Wb/Wh = 0.90). Te greatest thickness is situated on the inner quarter of the flanks. Te venter is large and smooth, weakly to moderately rounded. Te ribbing of the inner whorls (< 10 mm in diameter) consists of radial to slightly prorsiradiate, fine, primary ribs arising in pairs from an umbilical bulla. Between each pair there are three single, fine, intercalating ribs. From a diameter of 25 mm onward, it is possible to observe the nascent ribs on the umbilical wall. Te main ribs are single, strengthen and bear as strong umbilical spine rising above the umbilicus and a lateral tubercle/spine situated on the upper two-thirds of the flank from which two secondary ribs bifurcate. Tere are 10 to 11 main ribs per whorl. Intercalated ribs rarely bifurcate in the upper third of the flanks. In the last whorl, all ribs tend to incline forward on the upper third of the flank and terminate with a ventro-lateral tubercle of equal thickness, almost spiny. Te suture line is characterised by a significant degree of dissection. Te ventral lobe (E) is symmetrical and shorter than the first lateral lobe (L). Te first lateral lobe (L) is tripartite and very asymmetric, with a more developed branch facing the ventral lobe. Te second lobe (U2) is trifid and symmetrical.
Measurements (in mm):
Discussion. H. charcensis shows very strong affinities with the genus Teodorites ( Fig. 8 View Fig ). Te umbilical width index (U/D) is very similar, 0.35 to 0.36 in H. charcensis compared to 0.36 in the specimens described by Baraboshkin & Michailova (2006). Similarly, the whorl width index ratio (Wb/Wh) is found to be 0.87 to 0.96 in H. charcensis , in comparison to 0.95 to 0.96 in Teodorites . Additionally, H. charcensis exhibits a vertical umbilical wall, a smooth ventral face, and slightly convex outer whorls. It also displays sub-radial ribs, which originate from the umbilical border and bifurcate in some instances around the mid-flank. Furthermore, intercalated ribs are present. Te main ribs bear two or three rows of small tubercles, which are located at the umbilical, lateral, and ventrolateral positions. Additionally, the ventrolateral tubercles may exhibit slight flattening in certain areas. As observed in Teodorites , the suture lines of the type specimens exhibit a notable degree of dissection, with a narrow ventral lobe characterised by a high medial saddle and three lateral teeth, a deeper umbilical lobe that is almost symmetrically tripartite with a more developed branch facing the ventral lobe. Te first umbilical lobe is considerably shorter and less dissected. However, the preservation of type specimens of Haroella does not allow to define whether there is a hole in the umbilicus like in Teodorites . Te whorl section of H. charcensis exhibits some discrepancies with the description provided by Baraboshkin & Michailova (2006), although the photography (table 1, fig. 1c) appears to show an internal section with relatively subparallel sides. In contrast, Teodorites exhibits no such costal differentiation, with the main ribs bearing long umbilical and probably also lateral spines. It proceeds to a homogeneous ornamentation for a same diameter. Furthermore, main ribs and intercalated ribs tend to grow in bundles from the umbilical tubercle. However, given the very limited material available, it is impossible to rule out the possibility that both genera may be congeneric.
Despite the relatively poor state of preservation, the Moroccan specimen from Igourar leaves no doubt about its identity to the holotype. Te ontogenetic sequence is identical with the short trituberculate stage and development of mostly single coarse primary ribs towards the body chamber. Specimens have also in common a slow increase in the Wb/Wh ratio from an almost quadratic (pre-adult stage) to a slightly subquadratic whorl section on the body chamber. Te pre-adult trituberculate stage is unknown in the genus Lyticoceras , making it easy to distinguish.
Stratigraphic and geographic distribution. Haroella is a rare genus of the Tethys. At present, H. charcensis is known with certainty from its type locality (La Charce, France), from the Jura mountains (Mt Salève, Haute-Savoie, France) and from the Essaouira-Agadir Basin (Igourar, Imsouane). Most notably, Bert et al. (2021, p. 25, fig. 2) reported a Lyticoceras sp. nov. from almost the same stratigraphic position at Cheiron ravine (Alpes-de-Haute-Provence, France). Te specimen was not illustrated, and thus could prove to be another Haroella in the future. Similarly, the spot occurrences of Lyticoceras reported with Jeannoticeras by Bulot (1995) from below the main Lyticoceras beds in the Arc de Castellane, SE France, would benefit from further investigation.
Te first occurrence of the genus is observed at the Mt. Salève ( Fig. 3 View Fig ) with specimen MHNG GEPI 30234. Its green glauconitic patina suggests that it probably originates from the unit 3 of de Loriol (1861), which corresponds to the unit 4 of Joukowsky and Favre (1913). Tis fossiliferous phosphatic conglomerate was extensively excavated in the nineteenth century by de P. de Loriol (1861) and F.-J. Pictet, with the majority of the specimens now housed in the Muséum d’histoire naturelle de Genève. Te fossils are characterised by phosphatic internal moulds coated with glauconite among which S. lorioli , B. castellanensis , B. varappensis and L. buxtorfi were identified ( Fig. 3 View Fig ). Tis faunal association indicates the local L. buxtorfi Horizon , although the lowermost C. loryi Zone cannot be excluded as suggested by Strasser et al., (2018, fig. 13). Vocontian occurrences are actually only known in the C. loryi Zone , O. (J.) jeannoti Subzone. Te stratigraphic occurrence of the Moroccan specimen is difficult to precisely correlate with European occurrences, except that it is located in a stratigraphic interval between the last occurrence of Acanthodiscus and the first occurrence of Lyticoceras .
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