Eryma punctatum Oppel 1861
Creators: name: Devillez, Julien
name: Charbonnier, Sylvain
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Erymidae
Eryma
Eryma punctatum

description: 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.
description: Published as part of Devillez, Julien & Charbonnier, Sylvain, 2021, Review of the Late Jurassic erymoid lobsters (Crustacea: Decapoda), pp. 25-73 in Geodiversitas 43 (2) on pages 45-47, DOI: 10.5252/geodiversitas2021v43a2, http://zenodo.org/record/4486479