Jurapecten infrajurensis, 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 : 162-164

Jurapecten infrajurensis sp. nov.

urn:lsid:zoobank.org:act:203C99CB-ECC0-4663-B650-853B9085C0F0

Figs 6I–U , 7A–J

Diagnosis

Jurapecten in which the ambulacral base broadens abradially; sculpture of superomarginals comprises a reticulum of conjoined rugosities.

Etymology

From the Latin ‘ infra ’, in allusion to the occurrence of the species in the Lower Jurassic.

Material examined

The ambulacral illustrated here ( Fig. 6J ) is the holotype ( NHMUK PI EE 17989 ); paratypes are NHMUK PI EE 17990–17995 . All specimens are from middle Toarcian strata at Le Clapier (Département d’Aveyron, 62 km WNW of Montpellier, southern France; see Thuy 2012). Additional paratypes are fifteen ossicles (SNSB-BGSP 2020 XLV 16–30) from the upper Toarcian–lower Aalenian (possibly aalensis ammonite Zone) at Quedlinburg (Landkreis Harz, northern Germany; see Hess 2014).

Description

Marginals block-like, length slightly exceeding height, carrying a sculpture of rugosities, on inferomarginals aligned into transverse rows parallel with arm ( Figs 6O , 7I ). On proximal superomarginals ( Fig. 7C–D ) rugosities discrete and centrally placed single spine base present; on distal superomarginals rugosities conjoined by narrow radial struts, forming a reticulum of imperforate stereom (e.g., Figs 6N , 7G ). Ambulacrals ( Figs 6J–M , 7A, H ) waisted, with elongated heads and broad flat bases; abactinal ridge absent ( Fig. 7A ). Bases with broad padam site, slightly shorter than dadam ( Fig. 6J–L ). Adambulacrals ( Figs 6P, R–T , 7B, E–F ) with deep adadm site, distally placed padam and broad ada1 (best seen in Fig. 6R ); ada3 diffuse. Orals ( Fig. 6I, Q ) with tall, distally recurved apo, concave actinal face, low, lozenge-shaped body. Circumoral ( Fig. 6U ) with elongated poda, short doda.

Remarks

Jurapecten infrajurensis sp. nov. differs from J. hessi (see above) in the more elongated ambulacral base, and the more coarsely rugose sculpture of both infero- and superomarginals, which lack enlarged spine pits.

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. 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.