Jurapecten dhondtae, Gale & Jagt, 2021

Gale, Andy S. & Jagt, John W. M., 2021, The fossil record of the family Benthopectinidae (Echinodermata, Asteroidea), a reappraisal, European Journal of Taxonomy 755, pp. 149-190 : 166-168

Jurapecten dhondtae sp. nov.

urn:lsid:zoobank.org:act:3CEF9EA0-184A-4352-87FA-CC5F76FED11A

Fig. 8A–H, J–V

benthopectinid sp. 1 (? spp.) – Jagt 2000: 393, pl. 6 figs 1–4.

Cheiraster ? sp. – Blake & Jagt 2005: 190, pl. 5 figs 1–7.

Diagnosis

Jurapecten in which the marginal ossicles possess a coarsely rugose sculpture and the inferomarginals bear a single, large, laterally directed spine base.

Etymology

Named after Annie V. Dhondt (1942–2006), specialist of Cretaceous bivalves and close friend.

Material examined

The inferomarginal illustrated here ( Fig. 8F ) is the holotype ( NHMM JJ 10490a ), while the other figured ossicles in lot NHMM JJ 10490 are paratypes. Additional material includes around 50 isolated ossicles (lot NHMM JJ 9591 ). All material is from the upper Maastrichtian (Maastricht Formation, Emael Member, Lava Horizon) at the CBR-Romontbos Quarry, Eben Emael (Liège, northeast Belgium).

Description

Superomarginals ( Fig. 8A–D ) block-like, nearly equidimensional, elongating distally. Outer face with sculpture of dense rugosities of similar size and single, crater-rimmed spine base positioned towards abactinal-distal margin. Inferomarginals ( Fig. 8E–H, J–K ) asymmetrical, proximal margins broader than distal margins; inter-inferomarginal articulation facet close to actinal surface of plate ( Fig. 8J ), forming short projection. External face of inferomarginal with sculpture of coarse, rounded rugosities and single, large crater-rimmed spine base, positioned centrally, or slightly towards abactinal margin. Ambulacrals ( Fig. 8Q–V ) with elongated, bar-like ambh, broad, flat ambb, with large, flat surface for dadam and ada3, padam on short wing.Abactinal ridge and inferomarginal articulation absent ( Fig. 8V ). Adambulacrals ( Fig. 8L–M ) with concave abactinal face, actinal face with single subambulacral spine base. Enlargement of dadam ( Fig. 8P ) shows irregularly ridged region, similar to that seen on extant Pectinaster filholi (Perrier, 1885) ( Fig. 8I ).

Remarks

The marginal ossicles ( Fig. 8A–H, J–K ) are closely similar to those of Pontaster tenuispinus (von Düben & Koren, 1846) (compare with Fig. 4J–M, O–Q ) in shape, sculpture and spine base development,

but the ambulacrals ( Fig. 8Q–V ) possess elongated heads and lack abactinal ridges and inferomarginal articulation structures, and compare better with those of Jurapecten hessi and J. infrajurensis sp. nov. (see Figs 6J–M , 7M–O ).

The partially preserved specimen (NHMM MD 4105), described and illustrated by Blake & Jagt (2005), may be conspecific, but recrystallisation of all ossicle types precludes detailed comparison of the sculpture of infero- and superomarginal ossicles and ambulacral ossicles are too poorly preserved. The type material of J. dhondtae sp. nov., from the middle Emael Member, is ca 200 000 years younger than NHMM MD 4105, from the basal Gronsveld Member (compare Keutgen 2018).

Figures

Fig. 8 (next page). A–H, J–V. Jurapecten dhondtae sp. nov. A–D. Superomarginals in lateral view (NHMM JJ 10490b–e). E–H, J–K. Inferomarginals (NHMM JJ 10490f–j), in lateral (E–H, K) and distal (J) views. E. Original of Jagt (2000: pl. 6 fig. 2; NHMM JJ 9591i). F. Holotype (NHMM JJ 10490a). L–P. Adambulacrals, in actinal (M–N) and abactinal (L, O) views, with (P) enlargement to show ridges (lot NHMM JJ 9591). Q–V. Ambulacrals, in actinal (Q, S, U), abactinal (R, T) and proximal/distal (V) views (lot NHMM JJ 9591). — I. Pectinaster filholi (Perrier, 1885) (A.S. Gale collection, unregistered), enlargement of area on actinal surface of ambulacral. Provenance: A–H, J–V. Upper Maastrichtian, CBR Romontbos quarry, Eben Emael (Liège, NE Belgium), Maastricht Formation, Emael Member (Lava Horizon). I. Recent, Rockall Trough, northeast Atlantic. Abbreviations: d = distal; p = proximal. See Fig. 3 for detailed morphological terminology. Scale bars: A–H, J–O, Q–V = 1 mm; I, P = 0.2 mm.

Fig. 4 (next page). A, D, J–M, O–P, S–W, Z. Pontaster tenuispinus (von Düben & Koren, 1846), Recent (A.S. Gale collection, unregistered). A. Denuded radius, abactinal view. D. Lateral view of denuded arm. J–M. Superomarginals, lateral view. O–P, S, W. Inferomarginals, in lateral (O–P, S) and proximal (W) views. T. Circumoral ossicle. U–V. Oral ossicle. Z. Abactinal ossicle. — B, N, R, X. Nearchaster aciculosus (Fisher, 1910), Recent (A.S. Gale collection, unregistered). B. Lateral view of denuded arm. N, R. Marginal pair. X. Abactinal ossicle. — C, F–G, Y. Pectinaster filholi (Perrier, 1885), Recent (A.S. Gale collection, unregistered).C. Denuded arm, in lateral view.F–G. Marginal pair.Y. Abactinal ossicle. — E, Q. Cheiraster gazellae Studer, 1883, Recent (A.S. Gale collection, unregistered). E. Lateral view of denuded arm. Q. Lateral view of superomarginal. — H–I. Benthopecten simplex (Perrier, 1881), Recent (A.S. Gale collection, unregistered), lateral view of supero-/inferomarginal pair. Abbreviation: d = distal. See Fig. 3 for detailed morphological terminology. Scale bars: A–E = 5 mm; F–W = 1 mm; X–Z = 0.5 mm.

Fig. 3. A–C. Terminology used for adambulacrals and orals in the present paper. A. Actinal view of adambulacral of Luidia sp. — B–F. Benthopecten simplex (Perrier, 1881), Recent (NHMUK EE 13563). B. Abactinal view of adambulacral. C. Interradial view of oral ossicle. D–E. Adambulacral in actinal (D) and abactinal (E) views. F. Base of ambulacral in actinal view. — G–I. Cheiraster gazellae Studer, 1883, Recent (A.S. Gale collection, unregistered), ambulacral ossicles in abactinal (G), actinal (H) and proximal (I) views; note raised abactinal ridge (abr) and inferomarginal articulation (ma). — J–M. Pontaster tenuispinus (von Düben & Koren, 1846), Recent (A.S. Gale collection, unregistered). J–K. Oral ossicle in radial (K) and interradial (J) aspects. L–M. Supero- and inferomarginal pair. Abbreviations: d = distal; p = proximal; see Material and methods; after Gale 2011a: figs 10, 16. Scale bars: 1 mm.

Fig. 6 (next page). A–B, F.? Benthopectinidae. A–B. Inferomarginals, in lateral aspect (MHI 2183/7, MHI 2183/8). F. Oral ossicle in radial view (MHI 2183/9). — C, G. Jurapecten hessi Gale, 2011. C. Inferomarginal, in lateral view (NHMUK PI EE 17988). G. Oral ossicle, in radial view (NHMUK EE 13606; the original of Gale 2011a: pl. 20 fig. 10). — D–E, H. Pontaster tenuispinus (von Düben & Koren, 1846).D–E. Lateral view of inferomarginals.H. Oral ossicle (A.S. Gale collection, unregistered). — I–U. Jurapecten infrajurensis sp. nov. I. Oral ossicle, radial view (SNSB-BGSP2020XLV 31). J–M. Ambulacral ossicles, in actinal views (J = holotype, NHMUK PI EE 17989; K–L = paratypes, NHMUK PI EE 17990–17991; M = SNSB-BGSP2020XLV16). N–O. Marginal ossicles (paratypes, NHMUK PI EE 17992–17993). P, R–T. Adambulacral ossicles (paratypes), in actinal (P, R) and abactinal (S–T) views (R–S = NHMUK PI EE 17994–17995; P, T = SNSB-BGSP2020XLV 17, SNSB- BGSP2020XLV 19). I, Q. Oral ossicles, in radial view (paratypes: SNSB-BGSP2020XLV 15, SNSB- BGSP2020XLV 18). U. Circumoral ossicle (paratype: SNSB-BGSP2020XLV 20). Provenance: A–B, F. Maantang Formation (Carnian, Upper Triassic), sample C30, Jiancougou, Sechuan Province, China. C, G. Upper Oxfordian (Couches d’Effingen, bifurcatus ammonite Zone, stenocycloides ammonite Subzone), Savigna, near Orgelet, Département du Jura, France (Gale 2011b). D–E, H. Recent, Porcupine Trough, NE Atlantic. I, M, P–Q, T–U. Upper Toarcian–lower Aalenian (possibly aalensis ammonite Zone), Quedlinburg (Landkreis Harz, northern Germany; Hess 2014). J–L, N–O, R–S. Middle Toarcian, Le Clapier (Département d’Aveyron), 62 km WNW of Montpellier, southern France (Thuy 2012). See Fig. 3 for detailed morphological terminology. Scale bars: A–H = 0.4 mm; I–U = 0.2 mm.

Fig. 7 (next page). A–J. Jurapecten infrajurensis sp. nov., various ossicle types (paratypes). A, H. Ambulacrals, in lateral and actinal aspects, respectively (SNSB-BGSP2020XLV 21,SNSB- BGSP2020XLV 28). B, E–F. Adambulacrals, in actinal and abactinal views (SNSB-BGSP2020XLV 22, SNSB-BGSP2020XLV 25–26). C, G, J. Superomarginals, in lateral views (SNSB-BGSP2020XLV 23, SNSB-BGSP2020XLV 27, SNSB-BGSP2020XLV 30). D, I. Inferomarginals, in lateral views (SNSB-BGSP2020XLV 24, SNSB-BGSP2020XLV 29). — K–Y. Jurapecten hessi Gale, 2011. K, P, U. Adambulacral ossicles. K. Abactinal view (NHMUK PI EE 17996). P. NHMUK EE 13598 (the original of Gale 2011a: pl. 19 fig. 11). U. NHMUK EE 13599, the original of Gale (2011a: pl. 20 fig. 12). L. Circumoral ossicle (NHMUK EE 13605, the original of Gale 2011a: pl. 20 fig. 13). M–N. Ambulacral ossicles, in actinal and abactinal views, respectively (NHMUK EE 13595–13596, the originals of Gale 2011a: pl. 19 figs 8–9). O. Ambulacral, in proximal/distal view (NHMUK 13597). Q–S. Superomarginal ossicles (NHMUK EE 13601–13602; the originals of Gale 2011a: pl. 20 figs 6–7). T, V–W. Inferomarginals (NHMUK EE 13600, EE 13603–13604, EE 13608, the originals of Gale 2011a: pl. 20 figs 5, 8, 16). X–Y. Oral ossicles (NHMUK EE 13606– 13607, the originals of Gale 2011a: pl. 20 figs 10, 14). Provenance: A–J. Upper Toarcian–lower Aalenian (possibly aalensis ammonite Zone), Quedlinburg (Landkreis Harz, northern Germany; see Hess 2014). K–Y. Upper Oxfordian (Couches d’Effingen, bifurcatus ammonite Zone, stenocycloides ammonite Subzone), Savigna, near Orgelet, Département du Jura, France (Gale 2011b). Abbreviations: d = distal; p = proximal. See Fig. 3 for detailed morphological terminology. Scale bars: A–J = 0.2 mm; K–Y = 0.5 mm.