Data from: Mid-Cretaceous megaspore floras from Maryland, USA

Bulk maceration of unconsolidated Potomac Group sediments collected from 12 samples of middle – late Albian and early Cenomanian age on the Elk Neck Peninsula, Maryland, yielded 14 genera and 18 species of megaspores. The identified megaspores have affinities to both heterosporous ferns, e.g., Arcellites and Molaspora, and to heterosporous lycopsids, e.g., Erlansonisporites, Minerisporites, and Paxillitriletes. Morphological variation within species is high, and most morphotypes differ from established taxa in one or more characters. Two new species — Dijkstraisporites praetextus and Verrutriletes diversus—are proposed. The composition of these middle–late Albian and early Cenomanian floras is a mixture of taxa previously recorded from Aptian and Santonian floras in North America. In addition, a fragmentary strobilus of selaginellalean affinity containing a megaspore and microspores is described.采用批量浸解法(bulk maceration)处理采自美国马里兰州埃尔克内克半岛(Elk Neck Peninsula)、时代为中阿尔布阶-晚阿尔布阶及早塞诺曼阶(Cenomanian)的12件未固结波托姆群(Potomac Group)沉积物样品，共获得14属18种大孢子(megaspores)。本次鉴定的大孢子类群兼具异型孢子蕨类(heterosporous ferns，如Arcellites属、Molaspora属)与异型孢子石松类(heterosporous lycopsids，如Erlansonisporites属、Minerisporites属、Paxillitriletes属)的亲缘特征。各物种内部的形态变异程度较高，且多数形态型在一项或多项性状上与已确立的分类群存在差异。本文建立两个新种：Dijkstraisporites praetextus与Verrutriletes diversus。这套中阿尔布阶-晚阿尔布阶及早塞诺曼阶植物群的类群组成，混合了此前北美地区阿普第阶(Aptian)与桑托阶(Santonian)植物群中已报道的分类单元。此外，本文还描述了一件具卷柏目(selaginellalean)亲缘关系的孢子叶穗碎片，其内保存有大孢子与小孢子(microspores)。