Eryma punctatum Oppel, 1861

Devillez, Julien & Charbonnier, Sylvain, 2021, Review of the Late Jurassic erymoid lobsters (Crustacea: Decapoda), Geodiversitas 43 (2), pp. 25-73 : 45-47

Eryma punctatum Oppel, 1861

( Fig. 10 )

Eryma punctata Oppel, 1861: 359 ; 1862: 38, pl. 8, fig. 4. — Van Straelen 1925: 275. — Beurlen 1928: 165. — Glaessner 1929: 158. — Schweigert et al. 2000: 5, fig. 1b, pl. 2, figs 1-5. — Feldmann & Titus 2006: 64.

Eryma punctatum – Dietl & Schweigert 2001: 110, fig. 141. — Schweitzer et al. 2010: 24. — Schweigert 2015: fig. 542. — Devillez et al. 2016: 518, 524.

TYPE MATERIAL. — Holotype SMNS 3682 . TYPE LOCALITY. — Nusplingen , Baden-Württemberg, Germany. TYPE AGE. — Kimmeridgian .

DESCRIPTION

Carapace

Sub-cylindrical carapace; short, spineless rostrum; fusiform intercalated plate; deep and wide cervical groove, curved dorsally, subvertical and almost straight ventrally, strongly inflected at carapace mid-height, joined to dorsal margin and to antennal groove; deep antennal groove; short, shallow gastro-orbital groove originating as strong median inflexion of cervical groove; postcervical and branchiocardiac grooves convergent, sinuous, slightly inclined, not joined to dorsal margin; deep postcervical groove, more strongly sinuous than branchiocardiac groove, joined to branchiocardiac groove under the level of the gastro-orbital groove; deep branchiocardiac groove, joined to the posterior extremity of hepatic groove; hepatic groove concavo-convex; inferior groove joined to hepatic groove.

Pleon and uropods

Somites with wide subtriangular pleurites, directed backward, with a bulge at their basis; s2 with elongated pleurites, subrectangular anteriorly and subtriangular posteriorly; s5-6 pleurites shorter; telson with a median longitudinal crest; uropods as long as telson; uropodal endopods with a longitudinal carina; uropodal exopods with a diaeresis, and a longitudinal carina.

Cephalic appendages

Last segment of antennular peduncles (basipodite) articulated with two flagella, flagella made of numerous and short cylindrical articles; antennas made of numerous and short cylindrical articles; short, triangular scaphocerite.

Thoracic appendages

Elongated Mxp3, with small spines on the ventral margin of each articles excepted the two distal ones; chelate P1; P1 propodus short, subrectangular; narrow, inflated dactylar bulge; P1 fingers usually slightly longer than propodus, straight dorsally, equal in length, with a distal hook; occlusal margin with small teeth and a strong one on index proximal third; P1 carpus short, subtriangular; elongated P1 merus, with a short process at outer side of its ventral extremity; P2-P3 chelate.

Ornamentation

Carapace densely covered by rounded depressions; gastric region with an orbital spine; antennal region with an antennal spine; tergites and pleurites of pleonal somites densely covered by rounded depressions; uropodal exopods with a spine on external margin, anterior to the diaeresis; P1 propodus densely covered by small tubercles preceded by crescent-shaped depressions; P1 carpus densely covered by small tubercles, coarse tubercles along the distal extremity; P1 merus covered by small tubercles and strong spines directed forward along ventral margins; P2-3 and P5 with small and widely spaced depressions; P4 propodus with posterior spines.

DISCUSSION

This species is currently known by some specimens, but it has been firstly described by Oppel (1861) from an isolated P1 chela and assigned to Eryma . On the specimens recently found and preserved with the carapace we can observed the carapace groove pattern ( Fig. 10C ). The postcervical and branchiocardiac grooves are joined and the postcervical groove is not connected ventrally to hepatic groove. This pattern is characteristic of Eryma . Most of the specimens of E. punctatum exhibit short P1 fingers in comparison to their P1 propodus, which is unusual for the genus.

The ornamentation of the carapace of E. punctatum , only made of closely spaced depressions, is only shared with E. mandelslohi among Eryma , so its identification is easy. It is also the only Eryma with a dactylus clearly inserted under the level of inner margin, which is strongly prominent above the basis of the dactylus. The low position of the junction between postcervical and branchiocardiac grooves and the absence of ventral extension of the postcervical groove beyond this junction are two chatacterisitcs which distinguished E. punctatum from E. georgeii , E. jungostrix , E. mandelslohi , E. modestiforme , E. ventrosum , and E. westphali . Moreover, the P1 fingers of E. punctatum are straight, contrary to E. georgeii and E. ventrosum . They are also usually shorter than P1 fingers of E. georgeii , E. lerasi , E. major , and E. ventrosum .

Figures

FIG. 10. — Eryma punctatum Oppel, 1861 from the Kimmeridgian of Nusplingen (Germany):A, holotype SMNS 3682; B, specimen SMNS 66128; C, D, specimen SMNS 63849:general view (C), schema (D); E, specimen SMNS 63688; F, specimen SMNS 64960. Abbreviations: a, branchiocardiac groove; as, antennal spine; b, antennal groove; b1, hepatic groove;c, postcervical groove; d, gastro-orbital groove; di, diaeresis;e1e, cervical groove; i, inferior groove; ip, intercalated plate; Mxp3, third maxilliped. Photographs and line drawing: J. Devillez. Scale bars: 1 cm.