Biology Of The Famennian Heterocoral Oligophylloides Pachythecus

Abstract

ABSTRACT. Studies on the taxonomy and morphology of the Famennian heterocoral Oligophylloides have placed great emphasis on the character of the soft tissue, coloniality and distal development of the skeleton with regard to the construction of the wall. Here, the existence of soft tissue covering the entire skeleton of the colony is proposed. Thirty-eight branching specimens have been found in addition to the predominant single fragments of corallites; these should be regarded as colonial with a well-developed branching form. It is here proposed that the external wall grew not only at the distal end, and that its thickening did not result from the overlapping of tabulae, but was built independently of tabulae by the soft tissue covering the whole skeleton of the colony. The following new characteristics of Oligophylloides are described: a change in the position of septa, so-called`septal shifting', a rearrangement of the septal apparatus; the occurrence of aulos-like structures; a groove ornamentation on the external wall; and the granular microstructure of the axial part of septa. A detailed study of Late Devonian Oligophylloides corals shows that O. tenuicinctus Ro Âz Çkowska and O. pachythecus pentagonus Ro Âz Çkowska are synonymous with O. pachythecus Ro Âz Çkowska.KEY WORDS: heterocoral, Famennian, Oligophylloides, soft-tissue, coloniality, septa.T H E genus Oligophylloides was described for the ®rst time by Ro Âz Çkowska (1969), who distinguished two species: O. pachythecus (with two subspecies) and O. tenuicinctus, which are distinguished by the thickness of the external wall (protoheterotheca sensu Fedorowski 1991). These corallites lack calices, are much elongated, oval in transverse section, and have a smooth, thick or thin external wall and a maximum of 12 septa (according to the original diagnosis). The corallite has a`talon' (term questioned by Fedorowski 1991, p. 36) on its proximal part and a distal cone at the opposite end (Wrzoøek 1993). The material studied by Ro Âz Çkowska originated solely from the Famennian of the Holy Cross Mountains and was found in such localities as èago Âw, Kadzielnia, Gaøe Ëzice, Kowala and Jabonna. The genus is, in fact, relatively widespread through an area extending from Poland through Germany and France to Morocco (Weyer 1997).The original diagnosis of O. pachythecus, currently one of the most frequently studied species of the Heterocorallia, may still be supplemented with new features. Among them, the most important characteristics are: the centrifugal growth of skeletal elements (Wrzoøek 1978;Sutherland and Forbes 1981;Fedorowski 1991), the conical termination of the distal part (Wrzoøek 1981(Wrzoøek , 1993, and the lamellar microstructure of skeletal elements (Wrzoøek 1981; Karwowski and Wrzoøek 1987). At the same time, the morphology, increase and mutual relations of septa are often inferred from other, better documented, genera of the subclass Dividocoralia Fedorowski, 1991 because the sequence of septal insertion in the ontogeny and hystero-ontogeny of O. pa...

Epizoans immured in the heterocoral Oligophylloides maroccanus Weyer, 2017: a unique record from the Famennian (Upper Devonian) of Morocco

“…It is commonly accepted that the thick heterotheca characteristic of O. maroccanus was covered by soft tissue, which enveloped the entire skeleton of the paracolony (Chwieduk ; Berkowski ; Weyer ), while the polyps were located exclusively in its distal parts. The external soft parts protected the heterocoral branches against parasites, such as boring organisms and epizoans (Weyer ).…”

“…Both these taxa inhabited relatively deep‐water, apparently oxygen‐depleted environments of the late Famennian seas (Różkowska ; Scrutton ; Weyer , ; Berkowski ). The main characters distinguishing skeletons of the heterocorals from those of co‐occurring groups of extinct Palaeozoic corals, Tabulata and Rugosa, are the lack of the external theca (epitheca), everted calice (Wrzołek ; Fedorowski ; Weyer , ; Chwieduk ) and the unique centrifugal septal insertion (see detailed studies of Fedorowski ). These characters clearly show that the skeletons of heterocorals must have been covered by soft tissue, which produced more or less thick internal heterotheca (see Weyer , ).…”

Early development and coloniality in Oligophylloides from the Devonian of Morocco—Are Heterocorallia Palaeozoic octocorals?

“…Initially, three taxa were erected [ 1 ]: the type species Oligophylloides pachythecus Różkowska, 1969 and two additional subspecies: Oligophylloides pachythecus pentagonus Różkowska, 1969 and Oligophylloides pachythecus tenuicinctus Różkowska, 1969. The latter two taxa were synonymized with the type species, based on statistical measurements of the thickness of wall and diameter of central core in a large population from the type locality [ 3 ]. Further investigations [ 6 , 13 ] supported this view that the diameter and the thickness of the heterotheca are not sufficient to distinguish individual species, as they may vary within one specimen markedly.…”

“…The main characters distinguishing the skeletons of heterocorals from the skeletons of contemporary Palaeozoic rugose and tabulate corals is that they did not develop an external theca (epitheca) nor calices [e.g. 3 – 7 ]. Another distinguishing character is what has been referred to as the septal apparatus that is composed of dichotomously dividing septa, which formed centrifugally in the distal cone and in the axial part of the branch [see detailed discussion in 4 ].…”

“…On the other hand, the proximal parts have been already documented in several specimens from the Famennian Oligophylloides from the Holy Cross Mts. (Poland) [ 1 , 3 ] and interpreted as talons (extending attachment structures) where laminae of heterotheca are partly separated from each other and central lumen with a developed septal apparatus. However, the material investigated here shows that the specimens studied by these authors were incomplete and hence the early ontogeny was probably misinterpreted.…”