Allaire et al.—Early Ordovician eocrinoids from Morocco
specimen as R. dehirensis. They erected this new species to group all individuals corresponding to the description of R. destombesi but having one complete circlet of plates between infralaterals and laterals. Numerous intermediate states can be observed, ranging from one isolated additional plate to a complete circlet. This points toward the existence of one single species (R. destombesi) showing relatively important morpho- logical variations. Therefore, the morphology of Ubaghs’ ‘abnormal’ individual now appears to be entirely consistent with the intraspecific variability observed for R. destombesi. This identification is supported by the presence of four circlets of conical radial plates and by the absence of ornamentation on the thecal plates (smooth plates). Two other specimens (2367a1 and 1157h) were identified
701
Diagnosis.—Rhopalocystis with a small, stocky, strawberry- shaped theca, composed of six circlets of plates, one basal plate, one circlet of infralaterals (four plates), one circlet of laterals (six plates), three circlets of radials (columns of three plates). Basal wider than high; thecal plates convex, with facultative small ornamentation folds (granulations).
Occurrence.—Late Tremadocian (A. murrayi Zone), Fezouata Shale, Agdz-Zagora area (localities 809 = 1157 = 1725, 1773; Fig. 3) central Anti-Atlas (Morocco).
as R. dehirensis by Chauvel and Régnault (1986, text-fig. 3F, H). The specimen 2367a1 (Figs. 7.13, 8.4) was reexamined. It possesses two circlets of additional secondary plates (one between infralaterals and laterals and one between laterals and radials) and exhibits all morphological characteristics of the species R. destombesi (six primary circlets of plate, with four circlets of conical radials, no ornamentation). The specimen 1157h, designated as the holotype of R. dehirensis, could not be reexamined, but according to its description by Chauvel and Régnault (1986), it seems to show morphological characteristics of R. destombesi. Only the proximal portion of the adoral part of its theca is figured; one circlet of small secondary plates is present between infralaterals and laterals; and according to the description of the authors, the plates do not exhibit any ornamentation. The presence of small additional intercalary plates was the
main argument used by Chauvel and Régnault (1986) to justify the erection of a distinct species (R. dehirensis). This feature is related to intraspecific variability (see the preceding), and consequently, R. dehirensis is here considered as a junior synonym of R. destombesi.
Rhopalocystis fraga Chauvel, 1971 Figures 5.13, 9.1–9.4, 10.2, 10.4
1971 Rhopalocystis sp.; Chauvel, p. 44, pl. 1 figs. 9, 10. 1978 Rhopalocystis fraga; Chauvel, p. 54, text-fig. 11m. 1978 Rhopalocystis sp. A; Chauvel, p. 54. 1978 Rhopalocystis sp. B; Chauvel, p. 54, text-fig. 11q. 1986 Rhopalocystis fraga; Chauvel and Régnault, p. 870. 1986 Rhopalocystis sp. A; Chauvel and Régnault, p. 870. 1986 Rhopalocystis sp. B; Chauvel and Régnault, p. 870.
1971 Rhopalocystis fraga Chauvel, p. 43, pl. 1, figs.7,8;pl. 2, fig. 3.
Description.—The new localities did not yield additional material of R. fraga, but a part of the historical material was reexamined. The morphology of the observed specimens cor- responds to the descriptions given by Chauvel (1971, 1978). R. fraga has a small and stocky strawberry-shaped theca
composed of six joined and well-organized circlets of plates (e.g., Fig. 9.1, 9.2). The basal is higher than wide (e.g., Figs. 9.1–9.4, 10.2), and the laterals can also be higher than wide (holotype 1773a; Figs. 9.4, 10.2). The specimens 1725d' and g', not figured by Chauvel (1971, 1978), are here illustrated (Fig. 9.1, 9.2). The thecal length of R. fraga varies from 1.2 to 1.7 cm. The relief of the plates is very little pronounced; the radials are only slightly convex; the other thecal plates are relatively flat. So far, the brachioles and the stem have never been observed. Chauvel (1971) mentioned that the thecal plates of R. fraga
are covered with small granulations comparable to those of R. grandis. This ornamentation was only observed in the specimen 1773a (Fig. 10.2, 10.4). These granulations are smaller and less regular than those of R. grandis and can form small vermiculated ornamentation folds on some plates (e.g., laterals, Fig. 10.2, 10.4) more comparable to the ornamentation of R. zagoraensis. It is however difficult to determine whether the thecal plates of the other reexamined specimens (1725d' and g') were originally smooth or whether this simply results from the poor state of preservation of the examined latex casts, which were made more than 40 years ago.
Materials.—The original samples could not be reexamined. The observed material comprises latex casts of three original speci- mens of Chauvel (1971, 1978): one from locality 1773 (Fig. 1), showing three individuals (the holotype 1773a and the two paratypes 1773b, 1773c), and two from locality 809 (=1157 = 1725; Fig. 1): 1725d’ and1725g’, showing several molds of thecae and numerous isolated basal plates.
Holotype.—Specimen 1773a from the Fezouata Shale, Agdz area (locality 1773; Fig. 1), Anti-Atlas, Morocco (Chauvel, 1971, pl., 1 fig. 8; pl. 2, fig. 3).
Remarks.—The material left in open nomenclature (Rhopalo- cystis sp. A and sp. B) by Chauvel (1971, 1978) could not be directly reexamined. However, as the corresponding specimens
Figure 8. Rhopalocystis destombesi, photographs of latex casts dusted with ammonium chloride. (1) ML 20.268.381b; (2) 2367b1; (3) 2367 SR1; (4) 2367a1; (5) 2367 SR5; (6) 2367 SR6; (7) three specimens, 1157q1 (right side), 1157q2 (middle), and 1157q3 (left side); (8) two partially preserved thecae showing proximal parts of brachioles still in connection with the theca; the specimen 2367i (right side) is particularly large; (9) two specimens (1750a, b) with a theca almost entirely preserved (only the basal is missing); long parts of brachioles are preserved in connection with the theca; the brachioles of the specimen 1750a (left side) are remarkably well preserved: they seem to be at least twice as long as the theca, but certainly more because their distal extremities are missing; (10) two specimens, 1157e1 (right side) and 1157e2 (left side), exhibiting nipple-shaped umbos located in the middle of their plates; they are particularly pronounced in the specimen 1157e1. (1) Locality Z-F25, middle Floian (?B. jacksoni Zone); (2–6, 8) locality 2367, late Tremadocian (H. copiosus Zone); (7, 10) locality 809 (=1157 = 1725), late Tremadocian (A. murrayi Zone); (9) locality 1750 (=1737 = 1738), late Tremadocian (A. murrayi Zone). Scale bars = 1 cm.
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