Glyphea dressieri Meyer

Chény, Cédric, Charbonnier, Sylvain & Audo, Denis, 2023, Middle Jurassic lobsters (Crustacea, Decapoda) from Normandy, France, Geodiversitas 45 (4), pp. 139-161 : 143-149

publication ID	https://doi.org/ 10.5252/geodiversitas2023v45a4
publication LSID	urn:lsid:zoobank.org:pub:A477C4E9-3832-41CA-B6BF-BD48C38DFBEB
DOI	https://doi.org/10.5281/zenodo.7757628
persistent identifier	https://treatment.plazi.org/id/713F87CF-5446-FFF1-FF24-95BDFDD0F82F
treatment provided by	Felipe
scientific name	Glyphea dressieri Meyer
status

Treatment

Glyphea dressieri Meyer in Bronn, 1837

( Figs 3-9 View FIG View FIG View FIG View FIG View FIG View FIG View FIG )

Glyphea dressieri Meyer in Bronn, 1837: 480.

Palinurus squamifer J.-A. Eudes-Deslongchamps, 1842: 55, pl. 4, figs 4, 5.

For detailed list of synonymy see Charbonnier et al. (2013: 52, 53)

TYPE MATERIAL. — Glyphea dressieri : holotype by monotypy NHMW 1847/0051/1133 (d’Udressier coll.). In their monograph, Charbonnier et al. (2013) designated a neotype ( MNHN.F.A29540, Petitclerc coll.), just before the holotype was rediscovered in the Natural History Museum in Vienna, Austria, by Feldmann et al. (2015). An historical cast of this holotype was identified in Paris in Alexandre Brongniart’s collection ( MNHN.F.A59982). — Palinurus squamifer : 16 syntypes (A. Milne-Edwards coll., ex Eudes-Deslonchamps coll.) from the Upper Callovian of Ste-Scolasse, Normandy, France.

TYPE LOCALITY. — Quenoche, Haute-Saône department, France.

TYPE AGE. — Late Jurassic, early Oxfordian (Terrain à Chailles Formation).

ADDITIONAL EXAMINED MATERIAL. — See Table 1. View TABLE

DISTRIBUTION. — Late Bathonian-late Oxfordian.

DESCRIPTION

Carapace ( Fig. 4 View FIG )

Subcylindrical carapace (cephalothoracic shield), laterally compressed (holotype: CL = 42 mm, CH = 22 mm); short pointed rostrum, without spine and straight; anterior cephalic margin with optical and antennal notches; cephalic region covered by raised scales, aligned to form four longitudinal subparallel carinae: orbital, gastro-orbital, supra-antennal, and antennal carinae; gastro-orbital and supra-antennal carinae stronger than orbital carina; antennal carina strongly raised, with large spines directed forward; very deep cervical groove, steeply inclined, intercepting dorsal margin at angle of c. 80° at a distance of one-third of total length of dorsal margin from anterior; cervical groove ventrally joined to a shallow antennal groove, delimiting a narrow cephalic region; ventral margin of antennal-pterygostomial region strongly concave; antennal groove slightly rounded ventrally, forming slightly raised antennal lobe; antennal groove parallel to carinate ventral margin of cephalic region; sinuous gastro-orbital groove joined to cervical groove at the level of gastro-orbital carina, with two transverse branches parallel to cervical groove, extending from the dorsal margin to antennal carina, delimiting two raised gastro-orbital lobes; gastro-orbital lobes composed of three to four vertical rows of tubercles, one of which extends and forms antennal carina; deep postcervical groove joined dorsally, medially and ventrally to branchiocardiac groove, forming two raised squamose lobes separated by laterocardiac groove; anterior lobe wider than posterior one; shallow cardiac groove, upward-inclined, joined posteriorly to postcervical groove and anteriorly to dorsal margin; deep intercervical groove progressively shallower from postcervical to cervical grooves, slightly backward-directed; deep straight branchiocardiac groove not reaching dorsal margin of carapace; branchiocardiac groove, strongly inclined (c. 60°), at distance four-fifths of total length of dorsal margin from anterior; deep hepatic groove, strongly convex ventrally at intersection with branchiocardiac groove, straight and backward-directed in the intersection with antennal groove; strongly inflated adductor muscle insertion area; shallow inferior groove, convex posteriorly, joined to hepatic groove; carapace with large raised scales sub-aligned in cardiac and branchial regions and small raised scales in cephalic and hepatic regions; posterior and ventral margins bordered by very small tubercles; dorsal midline limited on each side by row of small rounded tubercles.

Epistome

Large epistome, swollen, convex, and subrectangular, not fused to the carapace but separated from it by a suture; lateral margins slightly sinuous; anterior margin characterized by the posterior limits of the arthrodial cavities of antennae, narrow sinus between these cavities; posterior margin with large rounded depression corresponding to front of mouth, marked by deep groove and small axial tubercle posteriorly directed; ornamentation with small tubercles, circular region between the posterior margin (axial tubercle) and anterior sinus smooth and depressed.

Cephalic appendages

Antennulae (a1) composed of antennular peduncle with three segments: pyriform precoxopodite; long, cylindrical, coxopodite; subrectangular basipodite; two short flagella articulated to distal part of basipodite; antennae (a2) composed of an antennal peduncle with three segments (short, stocky ischiocerite; thin, elongate merocerite with spinose lateral margins, and short, stocky carpocerite), a long multiarticulated flagellum, and an elongate, triangular, pointed scaphocerite; symmetrical, strong, and robust mandibles, with three-segmented palp: the third widens in ovate palette, palp fitting behind secant edge of mandible.

Pleon ( Fig. 5 View FIG )

s1-s6 with rounded tergum, tergal flanks with anterior and posterior grooves and tergopleuron separated from tergum by small constriction connecting points of articulation; short s1 with trapezoidal tergopleura; very large s2 tregopleuron with subrectilinear ventral margin and proximal part more elongate forwards, partially covering s1 tergopleuron; s2-s5 tergopleura with outer surface bearing two to three longitudinal lobes limited by a system of grooves and tuberculated ventral margin; s3-s5 tergopleura with ventral margin pointed in male and rounded in female; s6 with subtrapezoidal tergum and pointed to rounded tergopleura with distal notched for uropodal insertions; subrectangular telson with two deep lateral grooves; dorsal surface with two longitudinal carinae converging to a pair of flattened tubercles in proximal part; large scale located proximally to one pair of tubercles.

Thoracic appendages ( Fig. 6 View FIG )

Short Mxp2 with thin and elongate merus, short incurved carpus and short ovoid propodus; elongate Mxp3 (c. 80 %CL) with smooth elongate ischim, subrectangular merus; elongate, strong, and subchelate P1, short quadrate P1 ischium, long P1 merus, laterally flattened, with small scales dorsally and small tubercles ventrally,spiny ventral margin with strong distal spine; trapezoidal P1 carpus, covered by small tubercles with spiny ventral margin; P1 propodus and dactylus showing two different morphologies: long and slender propodus and large and elongate dactylus in male specimens; short and laterally flattened propodus and short, thin dactylus in female specimens; P1 propodus, strongly tuberculated, ventral margin with very strong and elongate spine (located in the first third anteriorly) followed by four small spines and one longer distal spine neighbouring an inflated tubercle at the articulation with dactylus; strong and elongate P1 dactylus, very large proximally and slender distally with a median longitudinal groove dorsally, covered by small tubercles, inner margin of P1 dactylus with setal pores; achelate P2-P5, relatively thin, uniformly covered by very small pits; elongate P2-P5 dactyli, with a median longitudinal groove dorsally.

Pleonal appendages

Only basal parts of pleopods 2-5 preserved; rounded uropods as long as telson; uropodal exopod with fringed diaeresis and longitudinal median carina slightly spiny, reaching ventral margin of the diaeresis and flanked by outer tuberculated ridge, shorter and stopped at level of the dorsal margin of the diaeresis; outer lateral margin with small distal spine; uropodal endopod with longitudinal median carina slightly spiny, reaching the ventral margin and flanked by an outer tuberculated ridge, shorter, not reaching the ventral margin and stopped at three quarters of the uropod height.

DISCUSSION

The configuration of the cephalothoracic grooves follows precisely that given in the diagnosis of Glyphea (see Charbonnier et al. 2013: 35 & fig. 11). The morphology of P1 propodus, and the scaly ornamentation of the specimens from Ste-Scolasse are diagnostic characters of Glyphea dressieri .

Following Bigot (1945: 20), Charbonnier et al. (2013) indicated that the type material of Palinurus squamifer was destroyed during the bombardment of Caen during the World War II. However, the careful examination of specimens in Alphonse Milne-Edwards’ collection leads us to identify the type material, probably sent to him or to his father Henri Milne Edwards by J.-A. Eudes-Deslongchamps himself. We ignore the precise history of these specimens, which were fortunately not destroyed but forgotten for about 150 years. After checking all the available syntypes, we confirm that P. squamifer is a junior synonym of G. dressieri .

Examination of the well-preserved specimens from Ste-Scolasse leads us to describe anatomical details that were unknown until today for this species: cephalic appendages, dorsal midline with rows of tubercles, ornamentation of first pereiopods, telson.

Sexual dimorphism

Étallon (1859) was the first to evoke sexual dimorphism in G. dressieri , but he had unfortunately only very few specimens and his hypothesis stemmed mainly from his observation of G. regleyana , for which he had numerous specimens.

Based upon 70 specimens, the present analysis is the first to allow the identification of a potential sexual dimorphism in Glyphea dressieri . Following Charbonnier et al. (2012), we made biometric measurements on 37 carapaces. The relation between the carapace length and height of G. dressieri is described by a linear model ( Fig. 7 View FIG ; Bravais-Pearson test indicates a significant correlation) as already observed in G. regleyana (see Charbonnier et al. 2012: fig 6). Our plot diagram does not show separate clusters that might be interpreted as being due to sexual dimorphism. The measured specimens form a relatively homogenous assemblage with a wide range of carapace sizes, although small and/or juvenile glypheids seem to be absent.

Forest & Saint Laurent (1989) recognized dimorphic features in the extant glypheid lobster Neoglyphea inopinata Forest & Saint Laurent, 1975 , in which the first pereiopods of males are longer and proportionally thinner than in females, and the pleonal somites show quadrate and sharp tergopleura in males, whereas they are more rounded in females. We therefore also examined the morphology of the first pereipods and tergopleura of pleonal somites. In the present sample, we identified specimens of G. dressieri with elongate P1 propodus and large and stocky P1 dactylus associated with sharply pointed (mucronate) s2-s5 tergopleura. They are probably male specimens. Other specimens show shorter P1 propodus and dactylus associated with rounded s2-s5 tergopleura. They are probably female specimens. This interpretation concurs with those proposed by Charbonnier et al. (2012) for G. regleyana and G. muensteri . We note that the secondary sexual characters in P1 and pleonal somites are less visible in G. dressieri than in other fossil glypheids, probably due to its overall strongly tuberculated and scaly ornamentation.

Similar evidence of sexual dimorphism have been documented in other fossil glypheoid species: Mecochirus longimanatus (Schlotheim, 1820) (Kimmeridgian-Tithonian, Germany; Garassino & Schweigert 2006; Charbonnier et al. 2021), Angarestia foresti ( Feldmann & Saint Laurent, 2002) (Cenomanian, Australia; Feldmann & Saint Laurent 2002) and Atherfieldastacus magnus (M’Coy, 1849) (Aptian, Mexico; see Feldmann et al. 2007 for details).To summarize, secondary sexual characteristics including features of the first pereiopods and/or tergopleura of pleonal somites seem to be relatively frequent in fossil glypheoid lobsters when their preservation allows their observation.

Ecdysis ( Figs 5G View FIG ; 8 View FIG )

Some specimens of G. dressieri are fossilized in very particular anatomical positions: the body is disarticulated with a disconnection between the carapace and pleon which form almost a right angle, while the pereiopods are grouped in a fan pointing to the pleon. Several specimens also correspond to isolated carapaces, which are dorsoventrally flattened (butterfly-shaped carapace) and sometimes split along the dorsal midline. All these positions are typical of different phases of molting process in glypheid lobsters (e.g., G. regleyana , G. muensteri ) as already described by Charbonnier et al. (2012). The active phase of ecdysis in G. dressieri probably started with the rupture of the integument between the carapace and the first pleonal somite. The butterfly-shaped carapaces indicate that the dorsal margin worked probably as a hinge that liberated the head of the molted animal. This was followed by extraction of the thoracic appendages and finally the pleon. The molted glypheid emerged, leaving the carapace displaced from the pleon, with their axes forming almost a right angle.

Reconstruction ( Fig. 9 View FIG )

Our new observations supply more accurate description and allow a detailed iconographic reconstruction of G. dressieri . The general views differ from those historically proposed by Eudes-Deslongchamps (1842) and Étallon (1859), but are a continuation of the work of Charbonnier et al. (2012). The reconstructions are more precise and highlight the sexual dimorphism in G. dressieri .

BIOSTRATIGRAPHY AND PALAEOBIOGEOGRAPHY

The first occurrence of Glyphea dressieri dates backs to the late Bathonian of United Kingdom. Woods (1927) figured specimens from the Cornbrash of Bedford and Kirtlington (Discus ammonite biozone after P. Taylor, comm. pers., 2017). Sellwood (1971) reported subtidal Thalassinoides burrow containing G. dressieri from the Bathonian, Great Oolite Group, White Limestone Formation of Oxfordshire. Van Straelen (1925) mentioned the species in the Bathonian of Courgains (Sarthe, France) but this age was wrong and the specimen from this locality is actually late Callovian in age and belongs to the Ste-Scolasse assemblage. Glyphea dressieri is a major component of the late Callovian Ste-Scolasse crustacean fauna (present work). It is also present in the early Oxfordian (Terrain à Chailles Formation) of Haute-Saône, France ( Charbonnier et al. 2012) and in the middle Oxfordian of Malton, United Kingdom ( Woods 1927). Recently, Charbonnier et al. (2013) figured an historical specimen (UCBL-EM 80056, Dolfuss coll.) from Trouville-sur-Mer and dated to the Kimmeridgian (Argiles à Ammonites Formation sensu Dollfus 1863). Actually, this formation is equivalent to the Argiles brunes de Villerville Formation, which is late Oxfordian in age, even if the upper part is sometimes confused with Kimmeridgian deposits ( Guyader et al. 1968). Thus, Glyphea dressieri seems limited to the Anglo-Paris Basin and has probably occupied distal platform palaeoenvironments from the upper circalittoral zone (Bathonian; Sellwood 1971) to lower circalittoral zone (Oxfordian; Charbonnier et al. 2012).