Jurapecten Gale, 2011

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 : 161

Genus Jurapecten Gale, 2011

Jurapecten Gale, 2011a: 84 , pl. 19.

Type species

Jurapecten hessi Gale, 2011 , by original designation.

Diagnosis

Benthopectinids which possess strongly rugose marginals; rugosities conjoined by thin radiating strips of imperforate stereom; ambulacrals lack abactinal ridges and inferomarginal articulation.

Assigned species

In addition to the type species, J. infrajurensis sp. nov. and J. dhondtae sp. nov., both described below.

Remarks

Jurassic–Cretaceous benthopectinids are locally common among isolated ossicles in washed residues. All share the same distinctive sculpture type of prominent imperforate rugosities, conjoined by radiating strips of stereom (e.g., Figs 6N–O , 7G, I–J ), absent on extant genera. In the extant genera Pontaster and Cheiraster , the rugosities on the superomarginals are smaller and more widely spaced (e.g., Fig. 4J–M, Q ), although the inferomarginal sculpture is similar to that seen in Jurapecten ( Fig. 6C–E ). Jurapecten also lacks a number of characters seen in all extant taxa, including an abactinal ridge on the ambulacrals (compare Fig. 7N–O with Fig. 5I, K–L, Q ), and there is no ambulacral articulation surface with the inferomarginal (compare Fig. 7N–O with Fig. 5I, K, Q ). Additionally, the ambulacral heads are more elongated in Jurapecten (e.g., Figs 6J, L , 8Q–U ). The absence of the abactinal ridge, to which the longitudinal arm muscles attach in all living genera ( Clark 1981), is a plesiomorphic feature of Jurapecten .

Figures

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.

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. 5 (next page). A, E, I–K. Cheiraster gazellae Studer, 1883 (A.S. Gale collection, unregistered). A, E. Adambulacral, in actinal and abactinal views, respectively. I–K. Ambulacrals, in abactinal, actinal and proximal views, respectively. — B, F, L–M. Pontaster tenuispinus (von Düben & Koren, 1846) (A.S. Gale collection, unregistered). B, F. Adambulacral, in actinal and abactinal views, respectively. L–M. Ambulacral, in abactinal and actinal views, respectively. — C, G, P. Benthopecten simplex (Perrier, 1881) (A.S. Gale collection, unregistered). C, G. Actinal and abactinal views of adambulacral, respectively. P. Enlarged view of actinal surface of ambulacral base. — D, H, N. Nearchaster aciculosus (Fisher, 1910) (USNM, unregistered). D, H. Adambulacral in actinal and abactinal views, respectively. N. Enlarged view of actinal surface of ambulacral base. — O, Q–S. Pectinaster filholi (Perrier, 1885) (A.S. Gale collection, unregistered). O. Enlargement of ambulacral base, actinal view. Q. Proximal view of ambulacral. R–S. Abactinal and actinal views of adambulacral, respectively. Abbreviations: d = distal; p = proximal. See Fig. 3 for detailed morphological terminology. Scale bars: A–N, P–S = 1 mm; O = 0.5 mm.

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.