A new definition of Adenoides eludens, an unusual marine sand-dwelling dinoflagellate without cingulum, and Pseudadenoides kofoidii gen. & comb. nov. for the species formerly known as Adenoides eludens

Abstract

ABSTRACTThe species Amphidinium eludens, as described by Herdman (1922; Proc. Trans. Liverpool Biol. Soc. 36: 18) based on her drawing in fig. 1, has been investigated for the first time by scanning electron microscopy and phylogenetic analysis. The morphological and molecular data reveal that this species is distantly related to other known dinoflagellates. Balech [1956, Rev. Algol., n. ser. 2(1–2): 30] cited Amphidinium eludens Herdman (1922, fig. 1) as the basionym of the type of Adenoides, while he described and illustrated Amphidinium kofoidii Herdman (1922, fig. 2) as Adenoides eludens. As the nomenclatural rules do not allow the change of basionym, we have re-defined the genus Adenoides based on the characteristics of Amphidinium eludens Herdman (1922, fig. 1). The thecal plate formula of Adenoides eludens is Po, 5′, 6″, 0c, 3+s, 5′″, 3p, 1″″. This species lacks a cingulum. The apical pore complex resembles that of peridinioid dinoflagellates, while the absence of a cingular groove is reminiscent of desmokont prorocentroids. We also propose Pseudadenoides kofoidii gen. & comb. nov. based on Herdman’s 1922 fig. 2 of Amphidinium kofoidii which was described by Balech in 1956 and re-named Adenoides eludens.