Ophiolofsson hendersonorum Thuy & Eriksson & Kutscher & Numberger-Thuy 2024
Creators: name: Thuy, Ben
name: Eriksson, Mats E.
name: Kutscher, Manfred
name: Numberger-Thuy, Lea D.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Echinodermata
Ophiuroidea
Phrynophiurida
Onychasteridae
Ophiolofsson
Ophiolofsson hendersonorum

description: Ophiolofsson hendersonorum gen. et sp. nov.
urn:lsid:zoobank.org:act: A24BEBB4-3C6C-4E9F-93F1-2340AE5B416D
Figs 4K–P, 7
Diagnosis
Species of Ophiolofsson gen. nov. with lateral arm plates of rounded rectangular outline; outer surface with a moderately coarse, dense tuberculation; outer proximal edge with two spurs, a ventral one with an even surface and a smaller dorsal one with a convex, knob-like surface; up to five relatively small but prominent lateral spine articulations arranged in a continuous row along the entire distal plate edge; up to six large, conspicuous, protruding ambulacral groove spine articulations along the ventral plate edge.
Etymology
Species named after the Canadian couple, Tim and Sephora Henderson, for their work with the influential and pioneering metal music outlet, BraveWords.
Type material
Holotype
SWEDEN • Gotland, Lau Backar; NRM PAL Ec38333.
Paratypes
SWEDEN • 2 specs; same data as for holotype; NRM PAL Ec38334, NRM PAL Ec 38335.
Type locality and stratum
Ludlow Series, Ludfordian Stage, uppermost part of the Lower Icriodontid conodont subzone sensu Jeppsson (2005), Eke Formation; Lau Backar, Gotland, Sweden.
Description
Holotype (Fig. 4K–L)
NRM PAL Ec38333 is a large dissociated proximal lateral arm plate, almost as high as long, with weakly concave dorsal edge, weakly convex ventral edge and strongly convex distal edge; proximal edge irregularly convex, with a central depression ventro-distally bordered by large, prominent and well-defined oval spur (SP) with even surface, and dorso-distally by smaller, prominent but poorly-defined spur with convex surface; outer surface with moderately coarse tuberculation except in depressed area of outer proximal edge; five relatively small, equidistant lateral spine articulations, extending from dorsal to ventral plate edge, with weak dorsal decrease in size; ventral edge devoid of incision but with six protrusions for ambulacral groove spines articulations. Inner side of lateral arm plate (Fig. 4L) with large, prominent, poorly defined vertebral articular knob in dorso-proximal corner of plate, with large, deep central depression; inner distal edge with rounded, bulging dorsal and ventral corners; tentacle notch large but relatively shallow and poorly defined; five large, conspicuous ambulacral groove spine articulations all along ventral plate edge.
Paratype (supplements)
NRM PAL Ec38334 (Fig. 4M–N) is a large dissociated median to distal lateral arm plate approximately 1.3 times as wide as high, well in agreement with holotype but with less strongly convex distal edge; proximal edge with two conspicuous knobs as in holotype; outer surface ornamentation as in holotype; spine articulations similar to those of holotype but only four instead of five; ventral edge with six small, inconspicuous protrusions of ambulacral groove spine articulations. Inner side with large vertebral articular structure; inner distal edge as in holotype but with even surface on ventro-distal edge; six small, poorly defined ambulacral groove spine articulations all along ventral edge; tentacle notch as in holotype. NRM PAL Ec38335 (Fig. 4O–P) is a dissociated proximal to median vertebra, roughly cylindrical, approximately 1.3 times as long as high and slightly wider than high, with rounded triangular cross section and slightly constricted waist; large, articular surface on proximal part of lateral sides matching vertebral articular knob on inner side of lateral arm plates; water vessel canal entirely enclosed by vertebra; distal face with two large, comma-shaped, prominent, well-defined zygocondyles, dorsalwards converging and with more prominent ventral tip; opening of water vessel canal encompassed by zygosphene.
Remarks
The lateral arm plates of Ophiolofsson hendersonorum gen. et sp. nov. differ from those of their congeners in having two characteristic spurs on the outer proximal edge, the ventral one of which shows a conspicuous, even surface, and in having up to five relatively small lateral spine articulations arranged over the entire distal plate edge.
Occurrence
Lau Backar.
description: Published as part of Thuy, Ben, Eriksson, Mats E., Kutscher, Manfred & Numberger-Thuy, Lea D., 2024, The beginning of a success story: basalmost members of the extant ophiuroid clade from the Silurian of Gotland, Sweden, pp. 216-247 in European Journal of Taxonomy 947 (1) on pages 232-233, DOI: 10.5852/ejt.2024.947.2631, http://zenodo.org/record/13365641