Schlueteria menabensis Secrétan, 1964

Charbonnier, Sylvain, Garassino, Alessandro & Pasini, Giovanni, 2012, Revision of Mesozoic decapod crustaceans from Madagascar, Geodiversitas 34 (2), pp. 313-357 : 313-357

Schlueteria menabensis Secrétan, 1964 ( Figs 23-25)

Schuleria [sic] menabensis Secrétan, 1964: 138-143 , pl. 13, fig. 1; pl. 14, figs 1-6; pl. 15, figs 1-6; pl. 16, figs 1-4; pl. 17, figs 3, 4.

Schlüteria tuberculosa Secrétan, 1964: 143-146 , pl. 12, figs 6, 7; pl. 13, figs 2-5; pl. 15, fig. 7; pl. 16, figs 5, 6; pl. 17, figs 1, 2. n. syn.

Schlueteria menabensis – Collignon 1970b: 35. — Taylor 1979: 24. — Schweitzer et al. 2010: 43.

Schlueteria tuberculosa – Schweitzer et al. 2010: 43.

LECTOTYPE. — MNHN.F. R 03920.

PARALECTOTYPES. — From the middle Santonian of the “Coupe de Berere”: 2 specimens (MNHN.F. A33084 , R03920, gisement 208, Texanites hourcqi zone); 3 specimens (MNHN.F. A33093 , R03908, R03922, gisement 209); 1 specimen (MNHN.F. A33045 , gisement 210). From the lower Campanian of the “Coupe de Berere (I and II)”: 9 specimens (MNHN.F.A33063, A33068, gisement 161, Anapachydiscus wittekindi and Eulophoceras jacobi zone); 2 specimens (MNHN.F. A33072 , gisement 162, Anapachydiscus wittekindi and Eulophoceras jacobi zone); 1 specimen (MNHN.F. A33088 , gisement 163); 3 specimens (MNHN.F.A33370, gisement 166); 7 specimens (MNHN.F.A33219, gisement 167); 3 specimens (MNHN.F. A33085 , gisement 169, Karapadites karapadensis zone); 10 specimens (MNHN.F.A33382, gisement 171, Karapadites karapadensis zone); 1 specimen (MNHN.F. A33069 , gisement 172, Karapadites karapadensis zone); 13 specimens (MNHN.F. A33220 , A33347, A33369 , gisement 184, Menabites boulei and Anapachydiscus arrialoorensis zone); 1 specimen (MNHN.F. A33099 , gisement 185, Menabites boulei and Anapachydiscus arrialoorensis zone); 5 specimens (MNHN.F. A33089 , A33102 , A33223, A33364 , R03891, gisement 191, Karapadites karapadensis zone); 2 specimens (MNHN.F.R03893, R03899, gisement 192, Anapachydiscus wittekindi and Eulophoceras jacobi zone); 1 specimen (MNHN.F.R03892, gisement 196, Upper Santonian); 1 specimen (MNHN.F.A33156, gisement 198, Anapachydiscus wittekindi and Eulophoceras jacobi zone); 1 specimen (MNHN.F.A33160, gisement 199); 1 specimen (MNHN.F.A33064, gisement 257).

Coupe de Ankilizato ,gisement 180),outer surface (D) with uniformly distributed small and large tubercles,inner surface (E) with aligned, large tubercles alternating with small ones,detail of small area (F) covered by strong, rounded tubercles at level of propodus-dactylus articulation ; G, P1 chela ( MNHN.F. R 03922, paralectotype, Coupe de Berere , gisement 209) showing occlusal margin of dactylus with one strong, very elongate proximal tooth and a strong median tooth ; H, P1 chela ( MNHN.F. A33045 , paralectotype, Coupe de Berere , gisement 210) showing very strong spine located at base of articulation of dactylus (note very wide opening) and curved with occlusal margins of dactylus and index not in contact ; I, P1 chela (O6905, National Museum , Prague) strongly tuberculate, showing occlusal margin of dactylus with two strong conical teeth located proximally and medially and with some strong pointed teeth distally, occlusal margin of index with a row of strong pointed, uniformely arranged teeth. Abbreviations: P1-P5, pereiopods 1 to 5. Scale bars: A-E, G-I, 2 cm ; F, 1 cm. Photographs by C. Lemzaouda ( MNHN) .

From the lower Campanian of the “Coupe de Ampolypoly- Antsirasira-Behamotra”: 3 specimens (MNHN.F.A33065, A33086 , gisement 324); 2 specimens (MNHN.F. A33138 , R03895, gisement 327, Pachydiscus grossouvrei zone); 1 specimen (MNHN.F.R03909, gisement 278, Texanites hourcqi zone); 2 specimens (MNHN.F.A33383, gisement 284, Anapachydiscus wittekindi and Eulophoceras jacobi zone).

From the middle Campanian of the “Coupe de Ampolypoly-Antsirasira-Behamotra”: 2 specimens (MNHN.F. A33071 , R03900, gisement 317).

Paralectotypes from the lower Campanian of the “Coupe de Bevaho”: 1 specimen ( MNHN.F. A33096 , gisement 253) ; 6 specimens ( MNHN.F. A33055 , A33067, A33087 , gisement 260, Karapadites karapadensis zone) ; 2 specimens ( MNHN.F. A33092 , gisement 261, Karapadites karapadensis zone) .

From the middle Campanian of the “Coupe de Andimaka”: 3 specimens (MNHN.F.A33052, R03894, gisement 201, Delawarella subdelawarensis and Australiella australis zone); 3 specimens (MNHN.F.A33372, gisement 189); 30 specimens (MNHN.F.A33066, A33373 , A33375 , A33384, R03901, gisement 202, Pachydiscus grossouvrei zone); 53 specimens (MNHN.F. A33047 , A33049, A33051 , A33060, A33090 , A33101 , A33387, R03896, gisement 203, Pachydiscus grossouvrei zone).

From the middle Campanian of the “Coupe de Ankilizato”: 1 specimen ( MNHN.F. R 03898, gisement 153, Pachydiscus grossouvrei zone) ; 1 specimen ( MNHN.F. A33097 , gisement 155, Pachydiscus grossouvrei zone) ; 5 specimens ( MNHN.F. A33043 , gisement 176, Pachydiscus grossouvrei zone) ; 1 specimen ( MNHN.F. R 03897, gisement 180, Pachydiscus grossouvrei zone) ; 1 specimen ( MNHN.F. A33121 , gisement 182, Pachydiscus grossouvrei zone) ; 10 specimens ( MNHN.F.A33042, A33151 , A33386, gisement 190) ; 2 specimens ( MNHN.F.A33366, gisement 199) .

All type specimens are from Belo-sur-Tsiribihina, Menabe, central Morondava Basin, Tulear Province.

TYPE LOCALITY. — “Coupe de Berere” (gisement 208), Belo-sur-Tsiribihina, Menabe region, central Morondava Basin, Tulear Province (here designated).

TYPE AGE. — Middle Santonian ( Texanites hourcqi zone).

ADDITIONAL MATERIAL EXAMINED. — Type material of Schlueteria tuberculosa : holotype ( MNHN.F. R 03888, Coupe de Bevaho, gisement 249, Pseudoschloenbachia (Pseudoschloenbachia) umbulazi zone, Upper Santonian); 1 paratype ( MNHN.F. R 03921, Coupe de Beantaly-Souromaraina, gisement 342, Texanites hourcqi zone, middle Santonian); 8 paratypes ( MNHN.F. A33091 , A33378, R 03886, R 03889, R 03890, Coupe Est de Bevaho, gisements 249 [ Pseudoschloenbachia (Pseudoschloenbachia) umbulazi zone, Upper Santonian], 251 [ Anapachydiscus wittekindi and Eulopoceras jacobi zone, Lower Campani- an]); 2 paratypes ( MNHN.F.A33365, R 03887, Coupe de Ampolypoly-Antsirasira-Behamotra, gisements 281 [Upper Santonian], 287 [ Anapachydiscus wittekindi and Eulopoceras jacobi zone, Lower Campanian]).

Unfigured material of Schlueteria menabensis : 8 specimens ( MNHN.F.A33061, A33100 , A33171, A33343, A33385, Coupe de Berere, gisements 165, 166, 171, 188, 184, 205, Menabites boulei and Anapachydiscus arrialoorensis zone, Lower Campanian); 4 specimens ( MNHN.F.A33059, A33070 , A33371, Coupe de Beantaly-Souromaraina, gisement 342, Texanites hourcqi zone, Middle Santoni- an); 4 specimens ( MNHN.F. A33108 , A33389, A33467 , Coupe Est de Bevaho, gisements 249 [ Pseudoschloenbachia (Pseudoschloenbachia) umbulazi zone, Upper Santonian], 318, Lower Campanian]); 1 specimen ( MNHN.F. A33103 , Coupe de Andimaka, gisement 201, Delawarella subdelawarensis and Australiella australis zone, Middle Campanian); 2 specimens ( MNHN.F. A33095 , Coupe de Ankilizato); 2 specimens ( MNHN.F. A33107 , Coupe de Ampolypoly-Antsirasira-Behamotra, gisement 304, Menabites boulei and Anapachydiscus arrialoorensis zone, Lower Campanian); 3 specimens ( MNHN.F.A33057, A33180, Coupe de Ampamba-Antsirasira, gisements 701, 708, 710, Karapadites karapadensis zone, Middle Campanian).

From unnamed outcrops: 5 specimens ( MNHN.F.A33048, A33056, A33057, A33080 , A33201, gisements 173 [Lower Campanian], 391).

From uncertain outcrops: 7 specimens ( MNHN.F.A33044, A33078 , A33104 , A33105 , A33106 , A33109 ).

All specimens are from Belo-sur-Tsiribihina, Menabe region, central Morondava Basin, Tulear Province.

STRATIGRAPHIC RANGE. — Middle Santonian to Middle Campanian.

DIAGNOSIS. — Cephalothorax with deep cervical groove delimiting a very wide branchial region and very narrow gastric region; markedly elongate rostrum, carinate dorsally; gastric region with two dorsally tuberculate carinae; P1 chela with short, stout palm and elongate dactylus and index incurved distally; small area covered by strong rounded tubercles at level of the propodus-dactylus articulation; occlusal margin of dactylus with one strong, very elongate proximal tooth, one strong median tooth, and a few pointed distal teeth in random arrangement; occlusal margin of index with a row of strong, pointed teeth in a uniform arrangement; P2 chela with short, inflated palm with smooth occlusal margin; uropodal exopod without diaresis.

DESCRIPTION

Cephalothorax subrectangular (CL = 36-56 mm, CH = 23-40mm); very elongate rostrum with smooth median carina; weak ocular incision delimited only by rounded antennal margin; gastric region with two

Mesozoic crustaceans from Madagascar dorsally tuberculate or smooth carinae curved, and converging to the base of the rostrum, the inferior one joining the lateral margin of the rostrum; area between the two curved carinae covered by aligned transverse small tuberculate lines; smooth antennal region; deep cervical groove arising in the first anterior quarter of the dorsal margin, strongly inclined, intercepting dorsal margin at an angle of c. 50°; cervical groove reaching the anterior ventral margin creating a strong inflection; cervical groove delimiting a very broad branchial region and very narrow gastric region; ornament of small pits uniformly distributed.

Abdomen with subrectangular somites; somite 1 smaller than others; somite 6 larger than preceeding ones; somites 2-5 of equal length;pleurae with smooth inferior margins; two different types of ornament on the abdomen: 1) terga of somites 1-6 without dorsal carina, pleurae with one lateral carina inducing a small ventral depression; and 2) terga of somites 1 and 6 without dorsal carina, terga of somites 2-5 with dorsal carina, subtriangular, very wide subtriangular pleurae with two carinae delimiting central depression; subrectangular telson with slightly sinuous lateral margins bearing two small spines, dorsal margin with two aligned tubercles.

Uropods with subrectangular endopod and exopod, articulated to bilobed basipodite; inner margin reinforced by marginal carina.

P1 bearing very massive homochelous chelae; propodus with strongly tuberculate dorsal margin and ventral margin bearing a carina of strong aligned spines directed forwards and decreasing in size anteriorly; very strong spine located at the base of articulation of the dactylus; small area covered in strong, rounded tubercles at level of propodusdactylus articulation; occlusal margin of dactylus with one strong, very elongate proximal tooth, one strong median tooth, and a few pointed distal teeth in random arrangement; occlusal margin of index with a row of strong, pointed teeth in uniform arrangement; opening very broad and curved with occlusal margins of dactylus and index not in contact; dorsal margin of dactylus bearing a median tuberculate carina; outer surface of propodus with uniformly distributed small and large tubercles; inner surface of propodus with aligned, large tubercles alternating with small ones; P2 chela well developed, with short, inflated palm; short dactylus and index with smooth occlusal margins; very elongate, thin P4-5 achelate.

DISCUSSION

Following re-examination of the Malagasy material studied by Secrétan (1964), we agree with her generic attribution. Secrétan (1964) distinguished Schlueteria tuberculosa from S. menabensis principally by (1) spiny carinae in the gastric region and (2) a dorsal carina on the terga of somites 2-5 in the former. We doubt the validity of S. tuberculosa for the following reasons: 1) all specimens of the two “species” originate from the same outcrops; 2) the configuration of the cephalic grooves is quite similar in both; and 3) P1 chelae are morphologically similar in both, irrespective of propodus size, as confirmed also by the type material of S. tuberculosa which has identical chelipeds to those of S. menabensis .

For these three reasons and in view of the incomplete state of preservation of material of S. tuberculosa , we synonymise both. Moreover,differences in ornament of carinae on the gastric region and on abdominal somites could be seen as reflecting intraspecific variation and/or sexual dimorphism. However, the material is not enough complete to determine which of these interpretations is correct. Because S. carinata Taylor, 1979 , was described on the basis of a poorly preserved specimen, retaining only the P2 ( Taylor 1979: 23, pl. IVa), Schlueteria menabensis represents, together with the type species S. tetracheles , the most complete member of the genus known to date. The original type of the latter, housed in the collections of the National Museum, Prague ( Czech Republic), has allowed us to compare this with the Malagasy species, so as to outline features in common as well as different characteristics.The two share the following characters: two longitudinal, parallel ridges on the cephalic region of the carapace; deep cervical groove strongly inclined forwards, creating a cephalic region which is smaller than branchial region; P2 chela short, stout, with inflated palm; pleurae of abdominal somites ending in a point; smooth subrectangular telson; smooth uropods; uropodal exopod without diaresis.Although the original sample of S. tetracheles comprises a few more or less complete specimens we have been unable to observe the rostrum that could have been thin and elongate as in the Malagasy species. The main difference between the two species is the structure of P1 chela: in S. tetracheles ( Fig. 24I), it is strong with a short, stout palm and elongate dactylus and index; the dorsal margin of the chela has a few variably sized spines in a random arrangement, while the ventral margin has a row of strong spines in a uniform arrangement, disappearing prior to the distal extremity; the occlusal margin of the dactylus has two strong conical teeth located proximally and medially and some strong pointed teeth located distally; the occlusal margin of the index has a row of uniformely arranged strong, pointed teeth; the surface of the chela is strongly tuberculate, while that of the dactylus has two rows of aligned tubercles; 4-5 tubercles aligned at the level of propodus-dactylus articulation; in S. menabensis the chela is strong with short, stout palm and elongate dactylus and index; the dorsal margin of the chela is smooth, while the ventral margin has a carina of strong, aligned spines directed forwards and decreasing in size anteriorly; the occlusal margin of the dactylus has a single strong, very elongate proximal tooth, one strong median tooth, and a few pointed distal teeth randomly arranged; the occlusal margin of the index has a row of strong, pointed teeth in uniform arrangement; the surface of the chela is strongly tuberculate with a row of tubercles aligned along the occlusal margin of the index; a small area is covered by strong, rounded tubercles at the level of the propodus-dactylus articulation. The main features observed in both species confirm the reconstruction of S. tetracheles by Fristch in Fristch & Kafka (1887).

In view of the above, we consider it important to select a lectotype for Schlueteria menabensis because Secrétan (1964) did not designate a holotype for it. This is MNHN.F.R03920, from Berere (gisement 208, Middle Santonian) which shows almost all the diagnostic characters of both species and genus.

Infraorder BRACHYURA Latreille, 1802 Section DROMIACEA De Haan, 1833