Palaeastacus loryi ( Van Straelen, 1923 ) Devillez & Charbonnier & Hyžný & Leroy, 2016

Devillez, Julien, Charbonnier, Sylvain, Hyžný, Matúš & Leroy, Lucien, 2016, Review of the Early Cretaceous erymid lobsters (Crustacea: Decapoda) from the Western Tethys, Geodiversitas 38 (4), pp. 515-541 : 528-530

Palaeastacus loryi ( Van Straelen, 1923) n. comb.

( Fig. 7F, G )

Eryma loryi Van Straelen, 1923: 93 ; 1936: 7, 8, pl. 1, fig. 6. — Glaessner 1929: 155. — Moret 1946: 50, fig. 1. — Roger 1946: 42. — Secrétan 1964: 69. — Förster 1966: 123. — Feldmann & Titus 2006: 64. — Schweitzer et al. 2010: 24.

TYPE MATERIAL. — Holotype ( OSUG, probably lost).

TYPE LOCALITY. — Malleval , Isère department, Rhône-Alpes region, southeastern France.

TYPE AGE. — Valanginian, Early Cretaceous.

DESCRIPTION

Subcylindrical carapace (holotype:CL = 60 mm, CH = 30 mm); deep cervical, postcervical and branchiocardiac grooves; short gastro-orbital groove originating as a slight median inflexion of cervical groove; short antennal groove; postcervical groove parallel to branchiocardiac groove, not joined to dorsal margin, joined to hepatic groove; branchiocardiac groove, joined to dorsal margin, slightly sinuous dorsally, joined to hepatic groove; concavo-convex hepatic groove, poorly preserved; carapace homogeneously and densely covered with small tubercles following crescent-shaped pits.

DISCUSSION

The holotype was not found in the palaeontological collections of OSUG at Grenoble, France. Our review of the species is based on the line drawing and the figure presented by Van Straelen (1923: fig. 93) and Van Straelen (1936: pl. 1, fig. 6) respectively. Firstly, the line drawing is misleading by exhibiting intercalated plate not visible on the figure. Indeed, the cephalic part clearly appears to be crushed. Moreover, the carapace grooves seem to be incompletely reported. The examination of the figures leads us to identify the postcervical groove parallel to the branchiocardiac groove and joined to the hepatic groove. This pattern is typical of Palaeastacus . Hence, the new combination Palaeastacus loryi ( Van Straelen, 1923) , n. comb. is proposed herein.

Other species of Palaeastacus are known from the Early Cretaceous such as Palaeastacus foersteri Taylor, 1979 (Barremian of Alexander Island, Antarctic; Fig. 3A, B ), Palaeastacus tenuidigitatus ( Woods, 1957) , n. comb. (Aptian of Queensland, Australia; see comments about Enoploclytia ), and Palaeastacus terraereginae (Etheridge Jr., 1914) (Barremian of Patagonia, Argentina; Aptian of Alexander Island, Antarctic; Aptian of Queensland, Australia).

A short, spiny P1 chela from the Albian of Texas was assigned tentatively to a new species Paramithrax H. Milne Edwards, 1834 by Whitfield (1883):? Paramithrax walkeri . Merill (1905) and Adkins (1928) followed Whitfield, but Rathbun (1935) emended his description and assigned this species to Palaeastacus . Rathbun (1935: pl. 3, figs 7-9) figured the holotype of P.walkeri ( Whitfield, 1883) and included new material in this species (carapace, P1 chela, left P1 cheliped). Stenzel (1945) assigned P.walkeri to Enoploclytia and refigured the carapace added by Rathbun (1935). He also figured new material (complete right P1 cheliped, left P1 dactylus, two pleons). Following Stenzel (1945), Richardson Jr. (1955) figured a right P1 cheliped under the name Enoploclytia walkeri ( Whitfield, 1883) but in a new variety: E. walkeri, var. schmidti . In his review, Förster (1966), later followed by Schweitzer et al. (2010), re-assigned the species to Palaeastacus .

Our review of all the figured specimens reveals that the holotype of P. walkeri fits the concept of Palaeastacus (short, rectangular propodus, strong spines on dorsal and ventral surfaces and on dactylus, narrow dactylar bulge). Furthermore, the P1 chelae figured byRathbun (1935: pl. 5, figs 1-3) and byStenzel (1945: pl. 38, fig.1), the P1 dactylus figured by Stenzel (1945: fig. 8), and the P1 chelipeds figured by Rathbun (1935: pl. 5, fig. 4) and Richardson Jr. (1955: fig. 108) are similar to the holotype of P. walkeri . The two pleons figured by Stenzel (1945: fig. 9, pl. 38, fig. 2) probably also belong to P. walkeri . However, the carapace figured by Rathbun (1935: pl. 4, figs 1-2) and by Stenzel (1945: pl. 39, fig.1)exhibits a long gastro-orbital groove, a sinuous postcervical groove joined to hepatic groove and a short branchiocardiac groove. This groove pattern is typical of Enoploclytia so this carapace cannot be regarded as P. walkeri but as a new species of Enoploclytia (see section Enoploclytia ).

In conclusion, with six species, Palaeastacus is the erymid genus including the most species for the Early Cretaceous.

Figures

FIG. 7. — Palaeastacus sussexiensis (Mantell, 1824) from the United Kingdom (A-E) and Palaeastacus loryi (Van Straelen, 1923) n. comb. from France (F, G): A, syntype SM B8892 of Enoploclytia imagei M’Coy, 1849 from the Cenomanian of Maidstone: part of carapace with right P1 chelae; B, C, lectotype NHMUK 41938 of Hoploparia scabra Bell, 1863 from the Albian of Folkestone: right lateral view (B) and line drawing (C); D, E, syntype SM B22448 (Carter coll.) of Phlyctisoma granulatum Bell, 1863 from the Albian of Cambridge: right lateral view (D) and line drawing (E); F, G, holotype (probably lost) of Palaeastacus loryi from the Valanginian of Malleval: original figure of carapace by Van Straelen (1936: pl. 1, fig. 6) (C) and line drawing (D). Abbreviations: a, branchiocardiac groove; b, antennal groove; b1, hepatic groove; c, postcervical groove; d, gastro-orbital groove; e1e, cervical groove; i, inferior groove; ω, attachment site of mandibular muscle. Photographs and line drawings: J. Devillez. Scale bars: A, 20 mm, B-G, 10 mm.

FIG. 3. — Anatomical terminology of erymid lobsters: A, B, holotype BAS KG.50.4 of Palaeastacus foersteri Taylor,1979 from the Barremian of Alexander Island, Antarctic: general view (A) and line drawing of the carapace (B); C, extant lobster Homarus gammarus (Linnaeus, 1758) with P1 chelae terminology. Abbreviations: a, branchiocardiac groove; b, antennal groove; c, postcervical groove; cam, carina of anterior margin; d, gastro-orbital groove; da, dactylus; db, dactylar bulge; ds, dorsal surface; e1e, cervical groove; i, inferior groove; im, inner margin; in, index; om, outer margin, PoA, post-orbital area; Sag, Sshaped anterior groove. Photographs: Hillary Blagbrough (A), Bart Braun (C). Line drawing: J. Devillez. Scale bars: 10 mm.