Zoobank registration: LSID urn:lsid:zoobank. org:act: E2EDCA4C-B0F7-46F1-AB7A-118C3575BE69.
Holotype: NMS G.2020.4.1.1, a partial skull and postcranial remains (Fig. 3).
Stratigraphic provenance: Kilmaluag Formation, Late Bathonian, Middle Jurassic (Retrocostatum Zone: Barron et al., 2012).
Type locality: Cladach a’ Ghlinne, Strathaird Peninsula, Isle of Skye, Scotland UK (Fig. 1).
Referred material: From the Kilmaluag Formation, Isle of Skye: Partial left dentary BRSUG 20571; NMS G.2018.27.1, fragment of right dentary in matrix. From the Forest Marble Formation of Kirtlington, Oxfordshire: NHMUK PV M46394, NHMUK PV M46448, NHMUK PV M46580 and NHMUK PV M46871, all upper molars. NHMUK PV M46316, NHMUK PV M46396 and, possibly, NHMUK PV M46607 (uncertain), all upper molars.
Etymology: Species named for the Cuillinensis, a mountain range on the Isle of Skye, Scotland, which overlooks the holotype locality; the skyline of the mountain range resembles the cusps and ridges of the teeth.
Differential diagnosis: Borealestes cuillinensis resembles Borealestes serendipitus in most features of the upper molars, but differs in having a more rounded cusp A, so that there is no anterior crest and no anterolabial crest on cusp A (Figs 5a and b, 6). Borealestes cuillinensis has a shorter anterolingual crest on cusp X than B. serendipitus, with a cuspule on the crest. Cusp Z is reduced compared to B. serendipitus. The anterior fovea is less distinct than in B. serendipitus. In the lower dentition, B. cuillinensis is almost indistinguishable from that of B. serendipitus, except for having slightly more pointed molar cusps. The lappets of the dentary do not enclose the cartilage of the Meckel’s sulcus of B. cuillinensis, unlike in B. serendipitus, and the mandibular symphysis is less distinct in B. cuillinensis than in B. serendipitus (Fig. 7).
Description: The holotype NMS G.2020.4.1.1 is a partial skeleton that, following preparation for high-resolution CT scanning, is contained within a series of small blocks of blue-grey micritic limestone between ~2 and 5 cm length. The dentaries and some skull elements are partially visible on the surface, and within the rocks are the skull, vertebrae, scapulacoracoid, humerus, radii, ribs and pes and manus elements. We infer that NMS G.2020.4.1.1 is an adult individual, as the last (ultimate) lower molar is positioned directly in front the coronoid process, as in adult specimens of Docodon victor (Schultz et al., 2017).