1020


Journal of Paleontology


were produced directly from the photographs in Adobe Illustrator CS2.


Methods.—The length and width dimensions of protaspid pro- tocranidia (N=15) and meraspid cranidia (N=6) were mea- sured from photographs by the optical image analyzer TpsDig2 (Rohlf, 2006). In several protaspid and meraspid specimens (N=15) preserved with the intergenal spines (or at least their bases), the transverse distance between these spines was mea- sured (intergenal spine separation sensu Webster, 2007). The measured parameters were plotted on a bivariate diagram using the PAST package (Hammer et al., 2001). Additional data for the analysis of protaspid and early


meraspid cranidial dimensions were collected from publications by Kautsky (1945), Zhang and Pratt (1999), and Dai and Zhang (2012). The protocranidial and cranidial width was used as a proxy of protaspid and meraspid sizes. The width or width ranges were taken directly from the text descriptions of the mentioned publications.


Repository and institutional abbreviations.—All figured speci- mens are numbered with the prefix Lund Original (LO) or Lund Reference (LR), and are housed at the Department of Geology, Lund University, Sweden.


Systematic paleontology


Morphological terminology used in the description generally follows Whittington and Kelly (1997), Palmer (1998, for the terminology of macropleural segments), and Hughes et al. (2006, for the terminology of the postcephalic part of the exoskeleton). Spines projecting from the postero-lateral corner of protaspid protocranidia (= posterior fixigenal spine of Palmer, 1962) or early meraspid cranidia (= intergenal spine) are here considered as homologous (cf., Størmer, 1942), and therefore in both cases are designated as intergenal spines. We follow the trilobite classification of Adrain (2011).


Superfamily Ellipsocephaloidea Matthew, 1887 Family Ellipsocephalidae Matthew, 1887


Remarks.—The concept of the family as presented by Jell and Adrain (2003) is followed here. The whole group, however, needs a comprehensive revision supplemented by parsimony analysis.


Genus Ellipsostrenua (Kautsky, 1945)


Type species.—Strenuella (Ellipsostrenua) gripi Kautsky, 1945 from the Grammajukku Formation (Cambrian Stage 4), Laisvall area, Lapland, northern Sweden.


Remarks.—Kautsky (1945) erected Ellipsostrenua as a subgenus of Strenuella Matthew, 1887 with Strenuella (Ellipsostrenua) gripiKautsky, 1945 as type species.Henningsmoen (1959) raised Ellipsostrenua to generic level, and this approach was later followed by other authors (e.g., Sdzuy, 1961; Rushton, 1966). Ahlberg and Bergström (1978) considered Ellipsostrenua to be a junior subjective synonym of Ellipsocephalus Zenker, 1833.


The type species of Ellipsostrenua differs, however, in several important respects from the type species of Ellipsocephalus, and Ellipsostrenua is here treated as a separate genus. The char- acters distinguishing Ellipsostrenua (Fig. 2) fromEllipsocephalus (cf., Šnajdr, 1958) include: (1) a tapering glabella without distinct anterolateral corners; (2) distinct genal spines; (3) pleurae terminating in sharp spines; and (4) a pygidium with narrow pleural regions, a wide, convex rhachis, and a pair of small spines.


Ellipsostrenua granulosa (Ahlberg, 1984) Figures 2, 4–7


1984 2009 2012 2015


Ellipsocephalus? granulosus Ahlberg, p. 356, fig. 6.


Ellipsocephalus? granulosus; Cederström et al., p. 495, text-fig. 5.


non 2009 Ellipsocephalus? granulosus; Cederström et al., p. 506, pl. 4, figs. 8–10.


Ellipsocephalus granulosus; Cederström et al., p. 167, fig. 15AC–AF.


Ornamentaspis? granulatus; Høyberget et al., p. 39.


Holotype.—An incomplete cranidium deposited in the type collections of the Geological Survey of Sweden, Uppsala, as SGU Type 3935 (Ahlberg, 1984, fig. 6A).


Diagnosis.—See Ahlberg (1984, p. 357).


Remarks.—Ellipsostrenua granulosa is similar to closely rela- ted species E. gripi and E. linnnarssoni (cf., Kautsky, 1945; Høyberget et al., 2015), but differs from them by: (1) strong


Figure 2. Reconstruction of the adult morphology of Ellipsostrenua granulosa (Ahlberg, 1984): (1) cranidium and librigenae; (2) thoracic tergite; (3) pygidium. Based on Ahlberg (1984). Surface sculpture omitted.


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