704


Journal of Paleontology 91(4):685–714


Holotype.—Specimen 1725a from the Fezouata Shale, Zagora area (locality 809 = 1157 = 1725; Fig.1), Anti-Atlas, Morocco (Chauvel, 1971, pl. 2, fig. 1a).


Diagnosis.—Rhopalocystis with a large-sized theca, made up of one basal, numerous irregular plates (infralateral and lateral areas undifferentiated), and three circlets of globular-shaped radials. Thecal plates ornamented with small punctiform granulations.


Occurrence.—Late Tremadocian (A. murrayi Zone), Fezouata Shale, Zagora area (localities 809 = 1157 = 1725, Z-F12c; Fig. 3), central Anti-Atlas (Morocco).


Description.—R. grandis is a large-sized species with a long theca composed of one basal plate followed by one large area made ofmany irregular plates (the infralateral and the lateral areas are not differentiated) and three circlets of radials. Each perradial area is composed of one column of three globular-shaped radial plates; the interradial areas consist of many small irregular plates. The thecal length of R. grandis can reach up to 90mm. Three of the six specimens originally identified as


R. grandis by Chauvel (1971) were reexamined (1725a–c; Figs. 9.5–9.7, 10.5). The thecae of specimens 1725a and 1725b are relatively well preserved. They are composed of numerous plates irregular in size and shape. The holotype (1725a; Figs. 9.5, 10.5) shows a well-preserved radius. Three globular- shaped radial plates (almost hemispherical) are visible, and the small irregular plates of the interradial area show numerous epispires. The specimen 1725c (Figs. 9.6, 10.5) corresponds to the aboral part of a theca, also composed of irregular plates; the proximal part of the stem is preserved in connection with the theca, and few cylindrical columnals of different sizes can be observed.


Although their shape and size are irregular, the plates of the


infralateral and lateral areas exhibit a characteristic pattern resulting from a growth mode by intercalation of new plates (Sprinkle and Guensburg, 2001). These particular successions of plates were already observed by Chauvel (1971), who identified the same plate pattern (P-i2-i1-i2-P) as in some other blastozoans. The large ‘P’ elements correspond to the primary plates (forming the initial transversal circlets of the theca). Intercalary plates ‘i1’ represent the secondary plates (medium- sized elements) that develop around the primary plates (P). Intercalary plates ‘i2’ correspond to tertiary plates (smallest elements) that form between primary and secondary plates. This type of growth pattern is visible in the four studied specimens (1725a–c, AA-TISa-OI-5a; Figs. 9.5–9.7, 10.1, 10.5). Only one new specimen of R. grandis was collected during


the last excursions in the Zagora area (AA-TISa-OI-5a, from the locality Z-F12c; Fig. 1). This specimen corresponds to a small fragment of theca, composed of a piece of a large plate with a rounded edge, and many other small irregular plates (Fig. 10.1). The thecal plates of R. grandis are ornamented with small punctiform granulations. This characteristic ornamentation, already mentioned by Chauvel (1971), is clearly visible in AA-TISa-OI-5a (Fig. 10.1, 10.3).


Materials.—One latex cast from locality 809 (=1157 = 1725; Fig. 1) containing three incomplete external molds of thecae: the


holotype (1725a) and two paratypes (1725b, c). One original sample from locality Z-F12c (Fig. 1) showing the partial exter- nal mold of a theca: AA-TISa-OI-5a.


Remarks.—Three specimens (1725d–f), originally figured by Chauvel (1971, pl. 2, fig. 1b) could not be reexamined. They consist of several fragments of thecae with incomplete stems and brachioles.However,Chauvel (1971) indicated that their stemwas long and flexible and consisted of an irregular alternation of cylindrical, more or less long, distally tapering columnals, as in R. destombesi. In these three figured specimens, the brachioles of R. grandis appear to be biserial and swollen at the base, also like those of R. destombesi (Chauvel, 1971, pl. 2, fig. 1b). The oral surface, the peristomial area, and the periproct (posterior inter- radial area) have not been observed. The diagnosis was here modified to better specify the main characteristics of this species. According to the present state of knowledge, themorphology


of R. grandis appears clearly distinct fromthat of all other species of Rhopalocystis. However, it cannot be excluded that future discoveries will make it possible to show that R. grandis might actually correspond to very large specimens belonging to another species.


Rhopalocystis havliceki Chauvel, 1978 Figures 4.4, 4.6, 5.2, 5.16, 11–13


1978 Rhopalocystis havliceki Chauvel, p. 55, pl. 5, figs. 2, 3, text-fig. 11f–l.


1978 Rhopalocystis sp. C; Chauvel, p. 55, pl. 5, fig. 4, text-fig. 11o – p.


1986 Rhopalocystis havliceki; Chauvel and Régnault, p. 870. 1986 Rhopalocystis sp. C; Chauvel and Régnault, p. 870.


2015 Rhopalocystis havliceki; Allaire et al., p. 24, text- fig. 2I, J.


2016b Rhopalocystis havliceki; Lefebvre et al., p. 10, text- fig. 8A, C.


Holotype.—Specimen 1725h4.5 from the Fezouata Shale, Zagora area, locality 809 (=1157 = 1725; Fig. 1), central Anti- Atlas, Morocco (Chauvel, 1978, text-fig. 11f–l).


Diagnosis.—Rhopalocystis with a large-sized theca, composed of one basal, one circlet of infralaterals (four plates) exhibiting one to three, more or less sharp protuberances (umbo); numer- ous laterals that can have a spine-shaped umbo; usually three circlets of radials (the first and the second radials are elongate and spine-shaped; the third radial is convex).


Occurrence.—Late Tremadocian (A.murrayi Zone), Fezouata Shale, Zagora area (localities 809 = 1157 = 1725, Z-F1, Z-F12c; Fig. 3), central Anti-Atlas (Morocco).


Description.—R. havliceki has a large-sized theca (Figs. 11–13), varying in length from 35 to 65mm. Its thecal width increases slightly but regularly from the proximal to the distal region. The theca of R. havliceki is composed of a basal plate, four infralaterals forming one circlet, a lateral area consisting of many plates with irregular shapes and sizes, and three circlets of radials. Each perradial area consists of one column of three


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