Jurapylocheles iwonae, Fraaije & Krzemiński & Van Bakel & Krzemińska & Jagt, 2012

Fraaije, René H. B., Krzemiński, Wiesław, Van Bakel, Barry W. M., Krzemińska, Ewa & Jagt, John W. M., 2012, The earliest record of pylochelid hermit crabs from the Late Jurassic of southern Poland, with notes on paguroid carapace terminology, Acta Palaeontologica Polonica 57 (3), pp. 647-654 : 652

Jurapylocheles iwonae sp. nov.

Fig. 4E, F.

Etymology: Named after Iwona Borek, who, together with her husband and daughter, collected numerous new decapod crustaceans from Oxfordian strata in the southern Polish Uplands.

Type material: The holotype ( ISEA I−F / MP/3956 /1533/08) is a near−complete shield (maximum length 2.0 mm, maximum width 1.9 mm) from Bzów; the single paratype ( ISEA I−F / MP/6193 /1577/10) also represents a near−complete shield (maximum length 3.0 mm, maximum width 2.8 mm) from Ogrodzieniec .

Type locality: Bzów , southern Poland .

Type horizon: Gregoriceras transversarium Zone and upper Perisphinctes plicatilis Zone (Middle Oxfordian; see above).

Diagnosis.—Shield as broad as long; small, sharp triangular rostrum; well−defined cervical groove effacing anteriorly, central gastric groove extending posteriorly into a distinct gastric process, pronounced postfrontal ridge with spine closely behind post−antennal projections.

Description.—Well−calcified shield, width equalling length, excluding rostrum; cervical groove most prominent centrally, initially convex posteriorly, proceeding slightly concavely and oblique forwardly and continuing almost parallel to the lateral border, effacing towards the post−antennal projections; dorsal surface of anterior part covered by coarse pits. A small, yet sharp and salient, triangular spine forming rostrum, with a short median crest; post−antennal projections small, each forming a blunt triangular spine faintly directed outwards; frontal ridge slightly concave and covered with granules; lateral regions straight and elongated, anteriorly with a globose, undivided massetic region; margins sloping and arched. Posterior margin of shield straight in centre and, following concave lateral curvature, extending longitudinally towards outermost post−antennal projections. Dorsal surface of shield with some swellings and additional faint furrows, anteriorly covered with coarse pits. Anterior central gastric groove extending posteriorly into a small gastric process; anterior portion of gastric region elevated, forming post−frontal ridge, curving backwards at level between post−antennal projections, having a triangular spine just behind post−antennal projections. Posterior carapace less well calcified and smooth, where preserved.

Remarks.—The new species is distinguished from the type species, J. malutka (Kimmeridgian, southern Germany; holotype MAB k.2453), by having post−frontal spines, a less angular cervical furrow and a more coarsely pitted anterior part of the shield.

Geographic and stratigraphic range.—To date, known solely from the southern Polish Uplands, northwest of Kraków, all material being of Middle to Late Oxfordian age.