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Complicated family relationships, or about taxonomic problems in the family Pyrenomonadaceae (Cryptophyceae)

Solarska Magdalena, Adamski Michał, Piątek Jolanta

Oceanological and Hydrobiological Studies

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2023

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Vol. 52, No. 3

299--306

EN

Cryptophytes, to which the Pyrenomonadaceae family belongs, are interesting organisms that occur almost allover the world and they are an important element of trophic chains in many ecosystems. The development of research methods and techniques, including electron microscopy and molecular studies, allowed for a better understanding of taxonomic relationships in this group of organisms. The Pyrenomonadaceae family currently includes three genera: Rhodomonas, Rhinomonas, and Storeatula, but their validityis being debated in the light of the latest data. The state of knowledge and the problems faced in the taxonomic revision of this family of cryptophytes are summarized in this article.

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New dimorphic species of the genus Rollierites Jeannet from southern Poland

Jain Sreepat, Mazur Marek

Annales Societatis Geologorum Poloniae

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2021

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Vol. 91, No. 4

405--418

EN

A new ammonite assemblage from the lower beds of the Ogrodzieniec Quarry (southern Poland), the only Callovian section in the middle part of the Polish Jura Chain, is described. It includes the presence of Kosmoceras rotundum (Quenstedt), followed by the first example of co-occurring micro- and macroconchs in the genus Rollierites (R. biplicatum sp. n.) and above it, the association of Euaspidoceras sp. and Peltoceratoides (Parawedekindia) gerberi Prieser. Both R. biplicatum sp. n. (m and M; microconch and macroconch) and K. rotundum are assigned to the late Callovian Lamberti Zone. P. (P.) gerberi characterizes the early Oxfordian Cordatum Zone. This is the first record of the genus Rollierites from Poland. This study extends the upper age limit of the middle Callovian Rollierites up to the late Callovian Lamberti Zone. On the basis of morphological and stratigraphical data, it is tentatively proposed that the origin of the early–middle Oxfordian Tornquistes may be in the middle–late Callovian Rollierites, rather than the previously proposed late Callovian Pachyceras. However, this is speculation, as the present data set is insufficient.

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A microconchiate Hypowaagenia Schweigert and Schlampp, 2020 (Aspidoceratidae, Hybonoticeratinae) from the Upper Jurassic of Southern Germany

Schweigert Günter, Schlampp Victor

Volumina Jurassica

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2020

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Vol. 18, no. 2

115--120

EN

The previously unknown microconch which corresponds to the recently introduced Late Jurassic aspidoceratoid ammonite genus Hypowaagenia Schweigert and Schlampp, 2020, is reported from beds of the topmost Platynota Zone or basal Hypselocyclum Zone of Franconia. This record indicates that these exotic ammonite findings are not of long-drifting necroplanktonic shells, but stem from animals that have spread over this area after immigration from the Tethys

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The tangled dimorphism within the ammonite Stephanoceratidae of the Late Bajocian

Pavia G.

Volumina Jurassica

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2006

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Vol. 4, no. 1

242-243

EN

Stephanoceratidae ammonoids achieved maximum diversification in the Upper Bajocian. At the topmost Lower Bajocian, two phyletic lineages produced important taxa which divided into a net of widespread supraspecific entities. The first one refers to the dimorphic Lokuticeras regarded by Galacz (1994) as the origin of the long-ranging subfamily Cadomitinae, from which the typically Late Bajocian Garantianinae derived at the beginning of the substage. The second lineage started from the dimorphic Phaulostephanus which was proposed by Pavia (2000) as the ancestor of an archipelago of minor taxa, such as Parastrenoceras, Subcollina, the polyphyletic superfamily Perisphinctaceae, the corresponding dimorphic genera Caumontisphinctes and Infraparkinsonia as possible stem of Parkinsoniidae. All these stephanoceratids are grouped in the literature into detailed dimorphic pairs, some of which do not need any particular comments, whereas others still lie in a undefined, not totally shared position. The following case-history could clarify the situation: * Cadomitinae: the coupling of Cadomites (M) and Polyplectites (m) is confirmed by all authors. * Garantianinae: Metz (1992) and Gauthier et al. (2002) clearly demonstrated that the inner whorls of Orthogarantiana (M) are homologous to the adult phragmocones of Strenoceras (m); consequently the previous combination Orthogarantiana-Torrensia (Pavia 1983) cannot be valid any longer. A distinct group of forms (cf. Pavia 1973, pl. 19) shows mature features which recall the microconchs of the genus Parkinsonia, in particular open umbilicus and very short apertural lappets: the possibility to transfer these forms to the parkinsonid family must be taken into account. Pseudogarantiana is accepted as the microconchiate counterpart of later garantianinids derived from Orthogarantiana, such as Hlawiceras and other supraspecific names. Moreover, an accurate taxonomic revision is necessary as the number of microconchiate taxa is too low when compared with that of the macroconchs. Benatinites, Parastrenoceras, Subcollina: they seem to be derived from Phaulostephanus by iterative evolution in different times. As to their dimorphism, (M) Benatinites matches the (m) Lugariceras (Schlögl et al. 2006). On the contrary the dimorphism of Parastrenoceras and Subcollina is far to be clarified; the microconchiate Torrensia is a good candidate, at least for Subcollina with which it shares the zigzag pattern of the ventral ribs.