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

description: Eryma lerasi (Étallon, 1861)
(Fig. 6)
Macrourites lerasi Étallon, 1861: 170, pl. 1, fig. 6.
Eryma dutertrei Sauvage, 1891: 91, pl. 4, figs 7-12. — Van Straelen 1925: 270, fig. 126. — Moret 1946: 51, fig. 2. — Secrétan 1964: 69. — Förster 1966: 117, fig. 20, pl. 16, figs 6-7. — Carriol 1991: 223. — Feldmann & Titus 2006: 63. — Schweitzer et al. 2010: 23. n. syn.
Eryma gracilimana Lahusen, 1894: 320, pl. 1, fig. 9. — Van Straelen 1925: 272. — Glaessner 1929: 155. — Gerasimov 1955: 25, pl. 8, fig. 8. — Birshtein 1956: 75. — Förster 1966: 122. — Gerasimov et al. 1995: 10, 30. — Ilyin 2000: 152, 154, table 1. — Feldmann & Titus 2006: 63. n. syn.
Eryma portlandica Woods, 1930: 79, pl. 22, figs 2-4. — Secrétan 1964: 69. n. syn.
Eryma lerasi – Van Straelen 1925: 276. — Glaessner 1929: 155. — Schweitzer et al. 2010: 24.
Clytia dutertrei – Glaessner 1929:115.
Eryma bedelta (pars.) – Förster 1966: 99.
Eryma gracilimanum – Schweitzer et al. 2010: 24.
TYPE MATERIAL. — Holotype lost (Förster 1966).
TYPE LOCALITY. — Haut-Rhin departement, Alsace-Lorraine, France.
TYPE AGE. — Not precised in original publication. However, considering the specimens that could be assigned to E. lerasi (see discussion below), all from Late Jurassic deposits, and the absence of sediments corresponding to the end of the Kimmeridgian-Tithonian in Haut-Rhin department (Skrzypek et al. 2008), it is reasonable to consider that the lost holotype was probably found in Late Jurassic deposits (Oxfordian-Kimmeridgian).
DESCRIPTION
Carapace
Sub-cylindrical carapace; very narrow post-orbital area; deep and wide cervical groove, curved dorsally, subvertical ventrally, joined to dorsal margin and to antennal groove; deep antennal groove; short, deep gastro-orbital groove, originating as a median inflexion of cervical groove; deep postcervical groove, slightly curved, joined to dorsal margin and to branchiocardiac groove; deep and narrow branchiocardiac groove, subparallel to postcervial groove, inflected towards its junction to hepatic groove, strongly inclined, joined to dorsal margin and to hepatic groove; deep and narrow hepatic groove, concavo-convex, joined to cervical groove; flat ω and χ areas; deep and wide inferior groove.
Thoracic appendages
Chelate P1; P1 propodus subrectangular, wide, strongly compressed dorso-ventrally; narrow dactylar bulge, slightly inflated, posteriorly delimited by a groove; thin, elongated fingers, equal in length, almost straight or slightly curved inward; occlusal margins with short and widely spaced conical teeth; P1 carpus short, subtriangular; elongated P1 merus.
Ornamentation
Carapace with a heterogeneous ornamentation; carapace covered by small rounded tubercles preceded by crescentshaped depressions, depressions wider and deeper in branchial region; P1 propodus, fingers and carpus densely covered by small tubercles preceded by shallow depressions.
DISCUSSION
Macrourites lerasi Étallon, 1861 was described on a P1 chela currently lost. It was assigned to Eryma by Van Straelen (1925). This assignation is supported by the subrectangular propodus, compressed dorso-ventrally, with elongated thin fingers curved inward, and a narrow dactylar bulge. Later, Förster (1966) integrated Eryma lerasi into the synonymy of Eryma bedeltum (Quenstedt, 1857). This synonymy is not maintained here because the P1 fingers of E. lerasi are thinner and its P1 propodus is clearly subrectangular and not trapezoidal.
The shape of the propodus, its fine and dense ornamentation, its thin fingers, their slight curvature and the narrow dactylar bulge are morphological features that E. lerasi shares with Eryma portlandica Woods, 1930 (Tithonian, United Kingdom; Fig. 6 G-J). So, E. portlandica is here considered as a junior synonym of E. lerasi. The illustration of Eryma gracilimanum Lahusen, 1894 (Tithonian, Russia; Fig. 6B), an isolated P1 chela, exhibits the same morphological features. So, this species is also considered here as a junior synonym of E. lerasi. Contary to E. lerasi and E. gracilimanum, the type material of E. portlandica includes carapaces. Eryma dutertrei Sauvage, 1891 (Kimmeridgian, France; Fig. 6 C-E) and the carapace identified as Eryma cf. boloniensis Sauvage, 1891 (Kimmeridgian, United Kingdom; Fig. 6K, L) by Förster (1966) share similar characteristics: the cervical groove is strongly inflected at carapace mid-height and curved dorsally, the junction between the postcervical and branchiocardiac grooves is low on the carapace, the ornamentation is dense, made of tubercles separated by well-marked depressions. So, we also add E. dutertrei and the specimen of E. cf. boloniensis of Förster (1966) within the synonymy of E. lerasi.
The carapace groove pattern of E. lerasi exhibits some characteristics distincts from other species of the genus. Indeed, the junction between the postcervical and branchiocardiac grooves is clearly lower than in E. georgeii, E. jungostrix, E. mandelslohi, E. modestiforme, E. ventrosum, and E. westphali. There is no ventral extension of the postcervical groove in E. lerasi contrary to E. georgeii, E. jungostrix, E. mandelslohi, E. modestiforme, E. ventrosum, and E. westphali. The morphology of the P1 chelae of E. lerasi are thinner than that of E. georgeii, E. major, E. veltheimii, and E. westphali. Finally, the ornamentation of E. lerasi, made of tubercles and depressions, differs from that of E. jungostrix, E. major, E. mandelslohi, and E. veltheimii, covered only by tubercles or depressions.
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 37-39, DOI: 10.5252/geodiversitas2021v43a2, http://zenodo.org/record/4486479