Eryma modestiforme ( Schlotheim, 1822 )

Devillez, Julien & Charbonnier, Sylvain, 2021, Review of the Late Jurassic erymoid lobsters (Crustacea: Decapoda), Geodiversitas 43 (2), pp. 25-73 : 42-45

Eryma modestiforme ( Schlotheim, 1822)

( Figs 8 ; 9 )

Macrourites modestiformis Schlotheim, 1822: 29 , pl. 2, fig. 3.

Astacus leptodactylus Germar, 1827: 100 , pl. 1, fig. 4.

Glyphea crassula Münster, 1839: 17 , pl. 8, fig. 5.

Glyphea elongata Münster, 1839: 18 , pl. 8, fig. 8, 11-12.

Glyphea laevigata Münster, 1839: 20 , pl. 9, figs 5-7.

Palaeastacus poeschli Schweigert & Röper, 2001: 5 , figs 3-4. — Garassino & Schweigert 2006: 11. — Schweitzer et al. 2010: 25. n. syn.

Glyphea modestiformis – Münster 1839: 17, pl. 8, fig. 9, pl. 9, figs 1-3. Eryma modestiformis – Bronn 1849: 579. — Oppel 1861: 358; 1862: 33, pl. 6, figs 5-8. — Van Straelen 1925: 271. — Beurlen 1928: 156, 157, 163, 164. — Glaessner 1929: 156. — Roger 1946: 42. — Kuhn 1961: 22. — Secrétan 1964: 69. — Förster 1965: 138, fig. 1, pl. 2, fig. 5. — Förster 1966: 118, fig. 21, pl. 16, figs 7-8 (non 9), pl. 17, fig. 1. — Schweigert & Garassino 2003: 178. — Fürsich et al. 2007b: 57. — De Grave et al. 2009: fig. 1B. — Feldmann & Schweitzer 2017: fig. 1c. — Odin et al. 2019: 652, fig. 6, ap. 1.

Astacus modestiformis – Quenstedt 1852: 268; 1867: 320; 1885: 409. — Fraas 1855: 94.

Eryma leptodactylina – Oppel 1861: 358; 1862: 35, pl. 7, figs 1-4. — Zittel 1885: fig. 873. — Secrétan 1964: 69. — Garassino & Schweigert 2006: 8.

Eryma leptodactylus – Van Straelen 1925: 273.

Clytia leptodactylina – Beurlen 1928: 170. — Vialle 1948: 65.

Clytia leptodactylus – Glaessner 1929: 116. — Kuhn 1961: 22.

Eryma elongata – Frickhinger 1994: 118, figs 201-202.

Eryma modestiforme – Schweigert et al. 2000: 4, fig. 1a, pl. 1, figs 1-5. — Dietl & Schweigert 2001: 53, 110, fig.86. — Schweigert & Röper 2001: 2, 7. — Garassino & Schweigert 2006: 6, fig. 8, pl. 1, fig. 1, pl. 11, figs 1-2. — Schweitzer et al. 2010: 24. — Charbonnier & Garassino 2012: 864, fig. 3B-C. — Karasawa et al. 2013: table 1, fig. 9A. — Hyžný et al. 2015: 375, fig. 3A. — Schweigert 2015: fig. 541. — Devillez et al. 2016: 518, 524. — Devillez & Charbonnier 2017: table 1, fig. 2a.

TYPE MATERIAL. — Holotype MFN 2236 P1383/2 MB.A.0252 . TYPE LOCALITY. — Eichstätt , Bavaria, Germany. TYPE AGE. — Kimmeridgian-Tithonian .

DESCRIPTION

Carapace

Sub-cylindrical carapace; slightly elongated, spineless rostrum; fusiform intercalated plate; orbital notch widely curved; narrow post-orbital area; elongated cephalic region, representing almost half of the length of the carapace; deep and wide cervical groove, almost straight dorsally, strongly inflected at carapace mid-height, joined to dorsal margin and to antennal groove; deep antennal groove; short, narrow gastro-orbital groove, oblique, originating as median inflexion of cervical groove; postcervical and branchiocardiac grooves subparallel, slightly curved, slightly inclined, not joined to dorsal margin; shallow postcervical groove, joined to branchiocardiac groove, with a short ventral extension; narrow, shallow branchiocardiac groove, joined to the posterior extremity of hepatic groove; hepatic groove concavo-convex, joined to cervical groove; inferior groove joined to hepatic groove.

Pleon and uropods

Somites with wide, short subtriangular pleurites, with a bulge on their basis; s2 pleurites wider than others; telson with a longitudinal median groove and two longitudinal crests along

lateral margins; 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; wide epistome, with a linear contact with the carapace; wide, subrectangular mandibles ( Fig. 9 A-C).

Thoracic appendages

Elongated Mxp3; chelate P1; P1 propodus subrectangular; slender, straight P1 fingers, longer than propodus, equal in length, sometimes with a small distal hook; occlusal margin without teeth; P1 carpus short, subtriangular; elongated P1 merus; P2-P3 chelate.

Ornamentation

Carapace with a homogeneous ornamentation; carapace densely covered by small tubercles and depressions; gastric region with an orbital spine; antennal region with an antennal spine; pleonal tergites and pleurites densely covered by small rounded depressions; telson covered by small depressions; P1 covered by small depressions; smooth P2-P5.

DISCUSSION

Eryma modestiforme is known by numerous specimens, almost complete. This is the most common erymoid of the lithographic limestones of southern Germany.

The type materials of Astacus leptodactylus Germar, 1827 ( Fig. 8C ), Glyphea crassula Münster, 1839 ( Fig. 8H ), Glyphea elongata Münster, 1839 ( Fig. 8D ), Glyphea laevigata Münster, 1839 ( Fig. 8 E-G) and Palaeastacus poeschli Schweigert & Röper, 2001 ( Fig. 8I ), from the same formations than E. modestiforme , share the same characteristics: a subrectangular propodus bearing longer fingers, these fingers are slender and straight, without teeth on their occlusal margins, the carapace ornamentation is dense, made of small tubercles and depressions. These characteristics support the integration of A. leptodactylus , G. crassula , G. elongata , G. laevigata and P. poeschli into the synonymy of E. modestiforme .

The ventral extension of the cervical groove seen on E. modestiforme is absent in E. lerasi and E. quadriverrucatum . The morphology of the P1 is also distinct from some other representatives of the genus. Indeed, the propodus is rectangular in E. modestiforme while it is trapezoidal in E. georgeii and E. mandelslohi . It is also relatively narrower than the propodus of E. georgeii , E. mandelslohi and E. quadriverrucatum . The almost straight P1 fingers of E. modestiforme contrast with the curved ones of E. georgeii , E. lerasi , E. veltheimii , E. ventrosum , and E. westphali . Finally, the fine ornamentation of E. modestiforme , made of tubercles and depressions, is clearly distinct from the ornamentation of E. georgeii , E. jungostrix , E. mandelslohi , E. veltheimii , and E. westphali .

Figures

FIG. 8. — Eryma modestiforme (Schlotheim,1822) and its synonyms from the Kimmeridgian – Tithonian of Germany: A, B, holotype MFN 2236 P1383/2 MB.A.0252 from Eichstätt: general view (A), schema (B); C, original figure of Garassino & Schweigert (2006: pl. 11, fig. 2) of the holotype of Astacus leptodactylus Germar, 1827 from Solnhofen; D, syntype BSPG AS VI 188 of Glyphea elongata Münster, 1839 from Solnhofen; E, F, syntypes of Glyphea laevigata Münster, 1839 from Solnhofen: specimen BSPG AS VII 198 (C), AS VII 194 (D), AS VII 197 (E); G, holotype BSPG AS VII 193 of Glyphea crassula Münster, 1839 from Solnhofen; H, holotype SMNS 64520 of Palaeastacus poeschli Schweigert & Röper, 2001 from Mülheim. Abbreviations: a, branchiocardiac groove; b, antennal groove; b1, hepatic groove; c, postcervical groove; d, gastro-orbital groove; e, eye; e1e, cervical groove; i, inferior groove; ip, intercalated plate; PoA, postorbital area; s1-s6, pleonal somites. Photographs and line drawing: J. Devillez. Scale bars: 1 cm.

FIG. 9. — Additionnal specimens of Eryma modestiforme (Schlotheim, 1822) from the Kimmeridgian–Tithonian of Germany: A, B, specimen BSPG AS VI 15 from Eichstätt: general view (A), schema of ventral side of cephalic region (B); C, specimen SMNS 64260 from Solnhofen; D, specimen MB.A2880 from Solnhofen; E, specimen BSPG AS VIII 79 from Eichstätt. Abbreviations: a1, antennulae; a2, antenna; as, antennal spine; di, diaeresis; ep, epistom; ip, intercalated plate; md, mandible; Mxp3, third maxilliped; ne, nephridiopore; sc, scaphocerite. Photographs and line drawing: J. Devillez. Scale bars: 1 cm.