Meyeria hurtrelleorum n. sp.

(Figs 4-6)

urn:lsid:zoobank.org:act: C57BEF1F-96DA-48B9-860D-9C88F70271DB

ETYMOLOGY. — The specific epithet honors the amateur palaeontologists Jacques and Françoise Hurtrelle who collected the studied specimens.

TYPE MATERIAL. — Holotype MPV 2013.1.289.1; 18 paratypes MPV 2013.1.289.2-17, 2013.1.289.74 (Hurtrelle coll.); one paratype IGR-PAL-153418 (Bara coll.).

TYPE LOCALITY. — Cricqueboeuf (Calvados Department, Basse-Normandie, France).

TYPE AGE. — Late Jurassic (late Oxfordian).

ADDITIONAL EXAMINED MATERIAL. — 59 specimens (MPV 2013.1.289.18-73; 2013.1.302.1, 2, Hurtrelle coll.) from the Oxfordian of Cricqueboeuf, Calvados, France.

DESCRIPTION

Carapace

Subcylindrical carapace, laterally compressed, with ogival cross-section (holotype: CL = 20 mm, CH = 10 mm); short, pointed rostrum, unarmed, with median dorsal depression; straight dorsal margin; rimmed posterior margin; convex ventral margin until antennal-pterygostomial region with slightly concave ventral margin; shallow orbit; short antennal spine; deep cervical groove strongly oblique, intercepting dorsal margin at angle of c. 45°, ventrally joined to antennal groove, delimiting narrow cephalic region; cephalic region with three longitudinal carinae: strongly raised and tuberculate orbital and gastro-orbital carinae; orbital carina shorter than gastro-orbital one, extending along the whole length of the cephalic region; raised tuberculate antennal carina, shortest among the cephalic carinae and slightly concave; equal space among the carinae; strong dorsal carina extending along the whole length of the carapace until rostral base; shallow postcervical and branchiocardiac grooves parallel, strongly inclined, directed toward posterior margin; postcervical groove joined ventrally to branchiocardiac groove, forming one elongate, straight lobe; elongate, wide cardiac groove, forward-inclined, joined to postcervical groove and to dorsal margin; deep hepatic groove, curved toward posterior, surrounding weak subcircular hepatic lobe; very short inferior groove, joined to hepatic groove and interrupted before reaching ventral margin; regions uniformly covered by tubercles.

Pleon

Pleon (including telson) about one-third longer than carapace; short s1; very large s2 with rounded anterior and ventral margins and straight posterior margin; s2 pleuron with longitudinal carina on middle portion; s3-s5 almost same in shape and size, with subtriangular pleura; s3-s5 pleura with longitudinal carina on middle portion; s2-s5 pleura with rimmed ventral margins; short subquare s6 with triangular pleuron; s1-s6 terga and pleura uniformly covered by small tubercles; subrectangular telson with subovate distal extremity and median part limited by lateral longitudinal carinae; proximal part with a pair of short carinae (formed by aligned setal pits) inclined downward and an axial pair of tubercles; tuberculate dorsal surface.

Thoracic appendages

P1 very poorly preserved (e.g., only P1 merus visible in specimen MPV 2013.1.289.9); elongate subchelate P2; subtriangular P2 ischium narrowing proximally; P2 merus twice longer than carpus with spiny lateral margins; P2 propodus with a tuberculate carina extending close to the upper margin; short smooth P2 dactylus, slightly incurved distally; elongate P3 incomplete distally; subrectangular P3 ischium; P3 merus twice longer than carpus; only P4 ischium preserved; P2-P3 meri, carpi, and propodi uniformly covered by small tubercles.

Pleonal appendages

Pleopods of s1-s5 not preserved; left uropodal exopod only preserved in specimen MPV 2013.1.289.12; uropodal exopod slightly longer than telson, with straight spiny diaeresis.

DISCUSSION

The mecochirid lobsters include four genera, Atherfieldastacus Simpson in Robin et al., 2016, Huhatanka Feldmann & West, 1978, Mecochirus Germar, 1827, and Meyeria M’Coy, 1849 (junior synonym: Jabaloya Garassino, Artal & Pasini, 2009). Based on Robin et al. (2016) and Charbonnier et al. (2021: 4), the studied specimens show morphological characters typical of Meyeria: carapace groove pattern with elongate and wide cardiac groove joined to dorsal margin (short cardiac groove joined to dorsal margin in Atherfieldastacus; extremely short and not joined to dorsal margin in Mecochirus), subcircular hepatic groove, and short inferior groove not joined to ventral margin (joined to ventral margin in Atherfieldastacus; absent in Mecochirus); carapace with ogival cross section (bevelled sublanceolate in Atherfieldastacus; ogival in Mecochirus). Huhatanka exhibits a very simple carapace groove pattern and a carapace without branchial carinae, very different from the Cricqueboeuf specimens. Finally, the absence of the branchial carinae, diagnostic character of Atherfieldastacus (e.g.GonzálezLeón et al. 2014), allow us to assign confidently the studied specimens to Meyeria.

Based on Charbonnier et al. (2021: 4), Meyeria includes nine species (see above-mentioned list), mostly restricted to the Early and Late Cretaceous. Only M. aragonensis (Garassino, Artal & Pasini, 2009) is known to date from the Oxfordian of Jabaloyas (Teruel, Aragón, Spain). Based on Garassino et al. (2009: 200, 201), the cephalic region with just one carina (gastro-orbital carina), regions of carapace covered by pits, the spiny ventral margins of s2-s5 pleura, and the spiny outer margin of the uropodal exopod rule out the belonging of the studied specimens of this species.

Charbonnier et al. (2013: 278) assigned Glyphea serratosae from the Jurassic of Buñol (Valencia, Spain) to Meyeria for the absence of the gastro-orbital groove and the elongate wide cardiac groove. As discussed by these authors, the age of this species is still controversial. Dupuy de Lôme & de la Revilla (1956) reported an indeterminate Jurassic age for the fossiliferous locality, whereas Vía (1976) proposed a Middle Jurassic age. Later, Solé & Via (1989) proposed a Late Jurassic age. Finally, Artal et al. (2008) returned to the Jurassic sensu lato. Though the age could be controversial, M. serratosae represented the only second species of the genus known to date from the Jurassic. Based on Dupuy de Lôme & de la Revilla (1956: 6), the subtriangular s2 pleuron rule out the assignment of the studied specimens to this species.

In conclusion, M. hurtrelleorum n. sp. is described to accommodate the studied specimens, representing for the genus the third report from the Jurassic and the second one from the Late Jurassic.