Eryma quadriverrucatum Trautschold, 1866

Devillez, Julien & Charbonnier, Sylvain, 2021, Review of the Late Jurassic erymoid lobsters (Crustacea: Decapoda), Geodiversitas 43 (2), pp. 25-73 : 47-49

Eryma quadriverrucatum Trautschold, 1866

( Fig. 11 )

Eryma quadriverrucata Trautschold, 1866: 20 , pl. 3, fig. 5. — Quenstedt 1885: 410. — Lahusen 1894: 313, 316, 318, pl. 1, figs 2-5. — Van Straelen 1925: 274, fig. 127. — Glaessner 1929: 158. — Gerasimov 1955: 24, pl. 8, figs 1-3. — Birshtein 1956: 74, 75. — Secrétan 1964: 70. — Förster 1966: 121. — Gerasimov et al. 1996: 9, 30, pl. 6, figs 1-3. — Ilyin 2000: 151. — Feldmann & Titus 2006: 64.

Eryma mosquensis Lahusen, 1894: 318 , pl. 1, figs 6-8. — Van Straelen 1925: 244, 276. — Glaessner 1929: 157. — Gerasimov 1955: 25, pl. 8, figs 5-7. — Birshtein 1956: 75. — Secrétan 1964: 70, 74. — Förster 1966: 122. — Gerasimov et al. 1995: 9, 30, pl. 4, figs 8-10. — Ilyin 2000: 152, 154, table 1. — Feldmann & Titus 2006: 64. — Schweitzer et al. 2010: 24. n. syn.

Eryma mosquensis pustulifera – Glaessner 1929: 157.

Eryma aff. quadriverrucata – Gerasimov 1955: 64, pl. 8, fig. 9. Eryma guadriverrucata – Ilyin 2000: 151, table 1.

Eryma quadriverrucatum – Schweitzer et al. 2010: 24.

TYPE MATERIAL. — Holotype stored in the Museum of Paleontology and Stratigraphy of the University of Saint Petersburg (not examined).

TYPE LOCALITY. — Choroshowo, Podmoskovié, Russia.

TYPE AGE. — Tithonian.

DESCRIPTION

Carapace

Sub-cylindrical carapace; fusiform intercalated plate; narrow post-orbital area; deep and wide cervical groove, strongly inclined and curved dorsally, subvertical ventrally, joined to dorsal margin and to antennal groove; deep and narrow antennal groove; short, deep gastro-orbital groove, originating as a median inflexion of cervical groove; deep postcervical groove, curved, not joined to dorsal margin, joined to branchiocardiac groove under the level of the gastro-orbital groove, without ventral extension; deep branchiocardiac groove, strongly inclined, strongly curved, with a strong inflexion towards its junction to hepatic groove, not joined to dorsal margin, joined to hepatic groove; shallow and narrow hepatic groove, concavo-convex, joined to cervical groove; inflated ω and χ areas; deep and wide inferior groove, joined to hepatic groove.

Pleon and uropods

Somites with subrectangular tergites; somites with subtriangular pleurites, directed backward, with a rounded bulge on their basis.

Thoracic appendages

Chelate P1; P1 propodus trapezoidal, compressed dorsoventrally, with a ventral surface inflated medially, median bulge bordered by a depression parallel to inner margin; narrow dactylar bulge, posteriorly delimited by a shallow and narrow groove; wide basis of the index; elongated P1 merus; thin P2-P5.

Ornamentation

Carapace densely covered by small tubercles surrounded by irregular depressions; intercalated plate with a row of small tubercles; cephalic region with an oblique orbital row of tubercles ended by an orbital spine; antennal region with an antennal spine; pleonal tergites and pleurites covered by small depressions; P1 propodus densely covered by small tubercles; smooth P1 merus; smooth P2-P5.

DISCUSSION

Trautschold’s (1866) description of Eryma quadriverrucatum is supported by an isolated carapace from the Tithonian of Russia. He assigned it to Eryma because of the short gastroorbital groove, the junction between the postcervical and branchiocardiac grooves and the sinuosity of the hepatic groove typical of the genus.

Eryma mosquensis Lahusen, 1894 (Tithonian, Russia; Fig. 10 E-F) was described on a fragment of P1 chela showing a subrectangular propodus, compressed dorso-ventrally and bearing thin, elongated fingers characteristics of Eryma . Gerasimov et al. (1995) later assigned to this species a carapace with convergent postcervical and branchiocardiac grooves, joined in the inferior half of the carapace, and with a fine ornamentation that gives a granular aspect to the carapace. E. quadriverrucatum exhibits very similar features. So, we consider E. mosquensis as a junior synonym of E. quadriverrucatum .

The junction of the postcervical and branchiocardiac grooves of Eryma quadriverrucatum is located very low on the carapace. It is very uncommon in Eryma , this junction is usually located at carapace mid-height, more or less at the level of the gastro-orbital groove, like in E. georgeii , E. jungostrix , E. mandelslohi , E. modestiforme , E. ventrosum , and E. westphali . Moreover, contrary to E. georgeii , E. jungostrix , E. mandelslohi , E. modestiforme , E. ventrosum , and E. westphali , the postcervical groove of E. quadriverrucatum does not have a ventral extension under its junction with the branchiocardiac groove. Both ω and χ areas are inflated in E. quadriverrucatum , while only one or none of them is inflated in E. georgeii , E. jungostrix , E. lerasi , E. mandelslohi , and E. ventrosum . The P1 propodus of E. quadriverrucatum is wider than that of E. jungostrix , E. lerasi , E. major , E. mandelslohi , E. modestiforme , E. veltheimii , E. ventrosum , and E. westphali . It is also subrectangular while that of E. georgeii , and E. mandelslohi is trapezoidal.

Figures

FIG. 11. — Eryma quadriverrucatum Trautschold, 1866 and its synonyms from the Tithonian of Russia: A, B, original figures of Trautschold (1866: pl. 3, fig. 5) of the holotype from Choroshowo: lateral view (A), dorsal view (B); C, original figure of Gerasimov (1955: pl. 8, fig. 3) from Ryazan; D, original figure of Gerasimov (1955: pl. 8, fig. 1) from Ryazan; E, F, original figures of Lahusen (1894: pl. 1, fig. 6) of one of the syntypes of Eryma mosquensis from Mneviki: dorsal view (E), ventral view (F); G, original figure of Gerasimov et al. (1995: pl. 4, fig. 9) from Moscow; H, original figure of Gerasimov et al. (1995: pl. 4, fig. 8) from Moscow; I, original figure of Gerasimov et al. (1995: pl. 4, fig. 10) from Moscow. Scale bars: 1 cm.

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.