A comparative analysis shows that the gladius morphology of Boreopeltis helgolandiaeEngeser & Reitner, 1985 (Aptian), the type species of Boreopeltis Engeser & Reitner, 1985, Boreopeltis sagittata (Naef, 1921) (Tithonian), and Boreopeltis smithi Fuchs & Larson, 2011 (Cenomanian) is fundamentally different from Boreopeltis soniaeWade, 1993 (Aptian). I therefore propose Eromangateuthis n. gen. in order to accommodate Eromangateuthis soniae (Wade, 1993).
Mary Wade (1993, fig. 5–8) introduced the new taxon Boreopeltis soniae from the middle upper Albian of Queensland (Australia). The species is based on several squid-like gladii, one of which has a length of about 1.2 m, hence, a mantle length twice as long as that of extant Enteroctopus dofleini (Wülker, 1910), the Giant Pacific octopus. Wade (1993) placed the new species into the genus Boreopeltis Engeser & Reitner, 1985 owing to supposed similarities. I investigated the type material of Boreopeltis soniae in 2005 and immediately recognized striking differences between Boreopeltis soniae and the type species, lower Aptian Boreopeltis helgolandiae Engeser & Reitner, 1985 and all other known species assigned to the genus Boreopeltis, i.e., lower Tithonian Boreopeltis sagittata (Naef, 1922) and Cenomanian Boreopeltis smithi Fuchs & Larson, 2011. Along with the presentation of the first Late Cretaceous member, Boreopeltis smithi, I have already mentioned doubts and excluded Boreopeltis soniae from the genus Boreopeltis (Fuchs & Larson, 2011, p. 242). The erection of a new genus is a logical consequence and is done herein.
MATERIAL & METHODS
The type specimens of Boreopeltis soniae are housed in the Queensland Museum in Brisbane. During my stay in Australia (2005), I investigated further specimens in the collection of the Kronosaurus Corner, a public museum in Richmond (northwest Queensland). Terminology and gladius parameters used below follow the Treatise Online, Part M, Coleoidea, chapter 9B: The gladius and gladius vestige in fossil Coleoidea (Fuchs, 2016). The diagnosis below matches the diagnoses and the system presented in the Treatise Online, Part M, Coleoidea, chapter 23G: Octobrachia (Fuchs, submitted 2019).
Superorder Octobrachia Haeckel, 1866
Suborder Prototeuthina Naef, 1921
Family Plesioteuthidae Naef, 1921
Eromangateuthis nov. gen.
Type species.—Boreopeltis soniae Wade, 1993.
Etymology.—After the so-called Eromanga basin in northeast Australia.
Diagnosis (new).—Large-sized plesioteuthids; gladius slender to moderately wide (gladius widthmax to gladius length 0.15–0.25) with pronounced solid median keel, which tapers anteriorly; median field very slender to slender (opening angle 10–15°, median field widthhypz to hyperbolar zone length 0.15–0.25); anterior margin distinctly convex, with lateral plate- or channel-like reinforcements; median field area very large (median field area to gladius area 0.85–0.95); lateral fields very slender to slender (lateral fields widthmax to median field widthmax 0.45–0.55); hyperbolar zones very short to short, difficult to determine (hyperbolar zone length to median field length 0.15–0.25); conus unusually deep, ventrally oriented (not funnel-like), patella shaped; soft parts unknown.
Included species.—Only the type species.
Stratigraphical and geographical range.—Lower Cretaceous (upper Albian) of Queensland (East Australia).
Differential diagnosis (Fig. 1).—Although Wade (1993) described the gladius morphology of Boreopeltis soniae in detail, comparisons with other prototeuthid octobrachians have been neglected. Actually, Eromangateuthis soniae and the Boreopeltis species complex have little in common; neither the anterior nor the posterior gladius part show a vague resemblance. A pronounced median keel present in Eromangateuthis n. gen. is absent in Boreopeltis, where the median line is not solid and only slightly elevated. Conversely, solid lateral reinforcements present on the median field of Boreopeltis are absent in Eromangateuthis n. gen. The lateral reinforcements in Boreopeltis are anteriorly projected; the shape Fuchs—Eromangateuthis n. gen.
of the anterior median field margin is therefore fundamentally different from Eromangateuthis n. gen., whose anterior margin is evenly rounded. The relative median field width of Eromangateuthis n. gen. is close to Boreopeltis, but the latter genus is missing the very narrow waist, which is caused by short and rapidly tapering lateral fields and hyperbolar zones. In Boreopeltis, the hyperbolar zone is significantly longer (hyperbolar zone length-to-median field length 0.50–0.70). Finally, the conus of Eromangateuthis n. gen. is distinct from a funnel-like conus typical for Boreopeltis and other plesioteuthids. The conus of Eromangateuthis n. gen. is unusual in being patella-like, similar to muensterelloid teudopseids (Fuchs & others, 2019).
Eromangateuthis soniae (Wade, 1993) n. comb.Figure 1D.1–1D.3
Type material.—Holotype (QMF25285), seven paratypes (QMF25775, 15209, 21988, 25284, 25286, 25288, 25289).
Type locality.—Marathon near Richmond (Queensland, Australia); southern anabranch of Flinders River (200 m upstream L813).
Type horizon.—Allaru Formation, middle upper Albian (see Wade, 1993).
Studied material.—Apart from the type material, I have studied specimens QMF25990, 25294, 52687, 39836; a specimen in the collection of the Kronosaurus Korner Museum in Richmond (Queensland, Australia), and a fragmentary conus deposited in Natural History Museum of London (NHMUK C.59211).
Description.—Eromangateuthis soniae is a plesioteuthid with a gladius of moderate width (gladius widthmax to gladius length 0.21). The slender median field (opening angle 10–11°, median field widthhypz to hyperbolar zone length 0.19) exhibits a pronounced solid median keel, which tapers anteriorly. The anterior margin of the median field is distinctly convex. The lateral margins are thickened by longitudinal plate- or channel-like reinforcements. The median field is very large (median field area to gladius area 0.91) compared to the lateral fields, which are slender (lateral fields widthmax to median field widthmax 0.52) and short (hyperbolar zone length to median field length 0.22). The posterior conus is unusually deep, ventrally oriented (not funnel-like), and therefore patella shaped. Soft parts are unknown. For a detailed description of the type material of Eromangteuthis soniae, see Wade (1993).