A phylogenetic system of Clavatoraceae (fossil Charophyta)

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Using the cladistic method of Hennig a phylogenetic system of Clavatoraceae (fossil Charophyta) is proposed. A number of new combinations arise from this study. The family Clavatoraceae is composed of three monophyla: (1) the Atopocharoidae, which are defined by presenting a utricle with a radial symmetry formed by the superposition of two whorls of spine-shaped bracts and includes traditional members plus traditional Echinocharoideae; (2) the Dictyoclavatoroidae, a monotypic taxon formed by Dictyoclavator fierii, which includes all traditional species of the genus and is defined by a utricle composed of a dense tissue of sub-polygonal cells; and (3) the Clavatoroidae, defined by showing a “Ringstruktur” calcification and a gyrogonite surrounded by a nodular layer, includes traditional members of the subfamily without Dictyoclavator. Atopocharoidae include five taxa: Diectochara andica, Echinochara spinosa, E. pekii, Globator maillardii and Atopochara trivolvis. Traditional systematics created a large number of anagenetic taxa within some of these species. Although these traditional taxa are biostratigraphically useful, they are by no means equivalent to evolutionary species. The ancestral species of the subfamily is at present unknown. D. andica, E. spinosa, E. peckii and A. trivolvis are considered as terminal taxa of the stem line. E. peckii is proposed as the ancestral species of G. maillardii. Clavatoroidae include an ancestral species ( Nodosoclavator bradleyi) and four genera each one with a different utricle architecture (Bauplan): (1) Clavator is defined by the apomorphy “bracts adjacent to the phylloid bearing fans of spine cells”. It is formed by six species plus the ancestral species and includes traditional members of Clavator, Flabellochara, Clypeator, Triclypella, Lucernella and Septorella. (2) Ascidiella is defined by the apomorphies “external layer of utricle constituted by two nodes of the phylloid” and “bracts bearing rosettes of petal-shaped cells”. It is formed by four species plus the ancestral species and includes the traditional genera Ascidiella and Embergerella. (3) Hemiclavator is defined by the apomorphy “external layer of utricle consisting of one or two whorls of triangular-shaped cells directly attached to the phylloid”. The genus contains one species and its ancestor and includes the traditional genus Hemiclavator and the species Nodosoclavator adnatus. (4) Pseudoglobator is defined by the apomorphy “external layer of utricle constitued of filiform cells radiating from the basal node”. It contains one species and its surviving ancestor and includes the traditional taxa Pseudoglobator fourcadei and P. paucibracteatus.