Type species. H. plurima n. sp., from the Table Cove Formation (Darriwilian), western Newfoundland, Canada (Laurentia).
Other species. Parapilekia jacquelinae Fortey, 1980, Valhallfonna Formation (Dapingian), Ny Friesland, Svalbard, arctic Norway (Laurentian-affinity East Svalbard Terrane); Macrogrammus pengi Edgecombe, Chatterton, Vaccari, and Waisfeld, 1999, Gualcamayo Formation (Darriwilian), San Juan Province, Argentina (Cuyunia Terrane); Macrogrammus rafi Edgecombe, Chatterton, Vaccari, and Waisfeld, 1999, Las Aguaditas Formation (Darriwilian), San Juan Province, Argentina (Cuyunia Terrane); Macrogrammus sp. of Waisfeld and Vaccari (2003, p. 303), Gualcamayo Formation (Dapingian), San Juan Province, Argentina (Cuyunia Terrane); Harebayaspis sp. (“Undetermined proparian species” and “Undetermined genus and species” of Ross [1958, p. 569, pl. 84, figs 9–11]), limestone clast in volcaniclastic breccia of the Valmy Formation (Floian), Lander County, Nevada, USA.
Etymology. From Hare Bay, in which the type locality of the type species is located, and the Greek noun aspis, shield. Gender is feminine.
Diagnosis. Eyes relatively anteriorly placed, rear of palpebral lobe just behind lateral termination of S2; area of fixigenal field present anterior to eye ridge but of restricted extent; L1 with subquadrate outline, S1 abaxially transverse, with adaxial posterior bend; librigenal field long (exsag.) and narrow (tr.); pygidium with 4–7 segments.
Discussion. A new genus is proposed for a group of Laurentian or Laurentian-affinity species known from the Floian to Darriwilian. Peng (1990) recognized that the only species of this group then known, Parapilekia jacquelinae Fortey, 1980, from the Dapingian of the East Svalbard Terrane, had cranidial similarities to the poorly known Macrogrammus scylfense Whittard, 1966, from the Floian of the Shelve Formation of Shropshire, England (Avalonia), and suggested that Fortey’s species should probably be assigned to Macrogrammus. Edgecombe et al. (1999) described two new species from the Darriwilian of Argentina (Cuyunia). They remarked on the unsatisfactory state of knowledge of M. scylfense, and also upon the obvious morphological differences between it and the better known Laurentian-affinity species. Nevertheless, they considered that two features - a large area of fixigena anterior to the eye ridge with the anterior section of the facial suture running straight forward rather than anteromedially - suggested relationship with the Avalonian species. We would argue that the large size of the anterior fixigenae is shared between M. scylfense and the Avalonian Darriwilian Macrogrammus sp. of Lane (1971, p. 37, pl. 7, figs 21a, b), but that this region is considerably smaller in all of the Laurentian species. Both Macrogrammus scylfense and Macrogrammus sp. of Lane (1971) differ from any of the Laurentian-affinity species in their extreme posterior eye position, with the palpebral lobe set opposite L1, and an obliquely set but nearly straight S1 which cuts directly posteromedially, versus an abaxially transverse furrow that is deflected posteriorly adaxially in the Laurentian-affinity group. For these reasons, we restrict Macrogrammus to the two Avalonian species that share these features, and propose Harebayaspis for the Laurentian-affinity group. Further evaluation of relationship would require much more knowledge of the Avalonian species.