Funeralaspis, Adrain & Pérez-Peris, 2023

Adrain, Jonathan M. & Pérez-Peris, Francesc, 2023, Funeralaspis n. gen.: a new odontopleurine trilobite from the early Middle Ordovician (Dapingian) of Death Valley, eastern California, USA, and the classification of Ordovician odontopleurines, Zootaxa 5336 (4), pp. 509-529 : 512

Funeralaspis n. gen.

Type species. Funeralaspis deathvalleyensis n. sp., from the Antelope Valley Formation (Dapingian), Inyo County, California, USA (Laurentia) .

Other species. Possibly “ Ceratocephala sp. indet.” of Fortey (1980, p. 102, pl. 25, figs 8, 9 [only; pl. 25, fig. 10 is ceratocephaline sp.]), Valhallfonna Formation, Olenidsletta Member (Floian), Svalbard, arctic Norway (Laurentia affinity East Svalbard Terrane).

Etymology. From the Funeral Mountains and the Greek noun aspis, shield. Gender is feminine.

Diagnosis. Anterior cranidial border long abaxially, with fine and dense tuberculate (or granular) sculpture; most dorsal cranidial surfaces with dense sculpture of fine and medium tubercles; eye and palpebral lobe set very posteriorly, rear of palpebral lobe nearly aligned with anterior of median occipital node; fixigenal field on posterior projections present as only a tiny strip; median occipital lobe large, elevated; pair of closely spaced, short occipital spines, not diverging posterolaterally, running, in most specimens, exactly posteriorly; doublure beneath LO very long sagittally; librigenal field very broad, with medium sized tubercles restricted to roughly the adaxial half; posterior border forming a sharp angle with base of the genal spine, nearly 90 degrees, ranging from slightly acute to slightly obtuse; librigenal lateral border typically with 11 border spines, border spines restricted to lateral border and not present on basal part of genal spine; genal spine about as long as main body of librigena and slender; hypostome relatively narrow (about 1.25 times as wide as long), with ventral sculpture of dense, relatively small tubercles; thoracic segments each with a pair of tubercles on the axial ring and a prominent tubercle at the base of each posterior pleural spine, remainder of sculpture of much finer tubercles; pygidium with two axial rings each with a pair of prominent spines, four medial border spines between the major spines, and two pairs of border spines lateral to the major spines; major spines considerably longer than other spines; apart from prominent tubercle on pleural region in front of second pair of pygidial spines, prominent tubercle at base of major spine and one or two slightly smaller tubercles distally on the major spine, sculpture of dense small tubercles on all dorsal aspects except the articulating half-ring.

Discussion. The morphology of Funeralaspis deathvalleyensis is far different from that of the much younger core group of Diacanthaspis (see discussion under that genus), nor does it compare closely with that of any of the mostly poorly known Laurentian species assigned herein to Diacanthaspis (s.l.). Given that it is represented by abundant well preserved silicified specimens permitting description of all sclerite types apart from the rostral plate, we propose a new Dapingian genus as a step toward a more comprehensive classification of Ordovician odontopleurines. Funeralaspis differs from Diacanthaspis (s.s.) in the lack of strong dorsal spinosity, lack of spines on the dorsal aspect of the base of the genal spine, presence of pygidial spines in which the major spines are strongly differentiated in length from the others, a lack of lateral fringing spines on any of the pygidial spines, and a lack of fringing spines on the thoracic and pygidial ring furrows.

As mentioned in the introduction, Fortey (1980, p. 102, pl. 25, figs 8–10) assigned three specimens from the Floian of Svalbard to Ceratocephala sp. indet. The pygidium does appear to represent a ceratocephaline, but Ingham in Ingham et al. (1986, p. 504) queried the assignment of two cranidia and Ramsköld (1991a, p. 163) considered them probably odontopleurine. If this is correct, they represent the oldest known member of the subfamily. They are very provisionally assigned to Funeralaspis , but at present there is very little information to classify the Svalbard species with any confidence. The specimens do have a prominent median node and a pair of slender occipital spines. The spines are more widely spaced than in F. deathvalleyensis , longer, and they diverge posterolaterally as opposed to being set directly posteriorly. The only other comparisons that can be made is that the Svalbard species has the palpebral lobes in a more anterior position and the interocular and posterior fixigena is significantly broader.