The genus Calastacus Faxon, 1893 in France with a new species from off Brittany (Crustacea, Decapoda, Axiidae) Author Ngoc-Ho, Nguyen Muséum national d’Histoire naturelle, Département Milieux et Peuplements aquatiques, 57 rue Cuvier, F- 75231 Paris cedex 05 (France) nngoc-ho @ mnhn. fr ho@mnhn.fr text Zoosystema 2011 2011-12-31 33 4 515 521 http://dx.doi.org/10.5252/z2011n4a4 journal article 10.5252/z2011n4a4 1638-9387 5166854 Calastacus laurentae n. sp. ( Figs 1 ; 2 ) TYPE MATERIAL . — Holotype : Continental slope south of La Chapelle Bank , France , Thalassa , 1973 , stn Z400, 47°33,4’N , 07°19’W , 1175 m , 22.X.1973 , 13h-15.35h, muddy sand and rocks: hermaphrodite, lc. 8 mm , lt. 18 mm ( MNHN Th 346), right pereopod 4, right uropods, left pereopods 2-4 missing. OTHER MATERIAL EXAMINED . — Continental slope south of Little Sole [Petite Sole] Bank , off Brittany , France , Thalassa 1973 , stn Z412, 48°1,6’N , 08°26’W , 1250 m , 24.X.1973 , 1.15h-3.05h, clayey mud ; broken specimen without carapace, abdomen (length 14 mm ) present along with right pereopods 1, 2, 4 and a few dissected mouth appendages ( MNHN Th 349). ETYMOLOGY. — The species is named for Michèle de Saint Laurent who had recognized it as a new species of Calastacus . DESCRIPTION Carapace ( Fig. 1A ) slightly shorter than abdomen, laterally compressed, upper border rounded.Cervical groove weakly defined dorsally, very faint laterally. Rostrum( Fig.1B )as long as antennular peduncle,with pointed tip, slightly depressed on upper side, bearing two pairs of large spines, one at base, the other distally on either side of rostral tip. Fine median gastric carina extending approximately from base of rostrum to halfway to cervical groove; two short carinae on either side and linked to it by two oblique branches. Abdomen ( Fig. 1G ) 1.2 times longer than carapace, pleura 1 pointed ventrally, those of segments 3, 4, and 5 with lower-distal spinule in holotype ( Fig. 1A ) as in specimen MNHN Th 349. Telson approximately 1.5 times as long as wide in specimen MNHN Th 349 ( Fig. 1G ), 1.70 times as long as wide in holotype ( Fig. 1C ) ; lateral borders with spinules similarly arranged but more numerous in holotype and a pair of lateral distal spines in both specimens; posterior border rounded. Eyes ( Fig. 1B ) globulous, hardly mobile. Second article of antennal peduncle ( Fig. 1A, B ) terminating distally in a point, with a lower distal spine; scaphocerite long, styliform, nearly reaching distal third of penultimate article of peduncle. Maxilliped 1 ( Fig. 2A ) with large epipod. Maxilliped 2 ( Fig. 2B ) with exopod, epipod partly broken. Maxilliped 3 ( Fig. 2C, D ) ischium of endopod with crista dentata bearing 11 teeth; merus with two lateral distal spines on lower border; exopod broken. Pereopods 1 ( Fig. 1A, D ) subequal in holotype , only right pereopod 1 present in specimen MNHN Th 349. Merus with small upper distal spinule and a spine at distal third of lower border, latter being more distinct in holotype ; propodus with fine longitudinal upper carina terminating in distal spinule in holotype , spinule absent in specimen MNHN Th 349 ; fixed finger nearly as long or slightly longer than palm with curved tip, cutting edge bearing three or four conical teeth; dactylus with curved tip and large rounded proximal tooth on cutting edge. Pereopod 2 ( Fig. 1E ) much smaller than pereopod 1, unarmed, fixed finger and dactylus with small pectiniform setae on cutting edge. Pereopods 3, 4, 5 ( Figs 1A ; 2F ) all unarmed, dactylus stout and short in pereopod 3, longer and slender in pereopods 4 and 5. Branchial formula of C. laevis was presented by de Saint Laurent (1972: 350). In the present species, except for the gills of maxilliped 1 ( Fig. 2A ) and pereopod 1 ( Fig. 1D ) those of other appendages were not examined. Female and male gonopores open on coxae of pereopods 3 and 5. A FIG. 1. — Calastacus laurentae n. sp. : A , lateral view; B , anterior part of carapace; C , telson; D , pereopod 1; E , pereopod 2; F , pereopod 4; G , abdomen, telson and uropods. A -C , holotype (MNHN Th 346); D -G , specimen MNHN Th 349. Scale bars: 1 mm. FIG. 2. — Calastacus laurentae n. sp. : A -C , maxilliped 1, 2 and 3; D , ischium of maxilliped 3, mesial view; E , pleopod 1; F , G , pleopod 2 and 3. A -D , F , G , specimen MNHN Th 349; E , holotype (MNHN Th 346); Scale bars: 1 mm. Pleopod 1 ( Fig. 2E ) two-articulated, proximal article long and slender, distal article larger with a small internal projection, no visible appendix interna. Pleopod 2 ( Fig. 2F ) biramous, exopod slender, endopod divided into a basal article and a appendix masculina of two faintly separated articles carrying tiny setae; short appendix interna fused to base of appendix masculina. Pleopods 3-5 ( Fig. 2G ) biramous, exopod and endopod slender with long appendix interna. Uropods ( Fig. 1G ) about as long as telson, posterior border rounded, endopod with one external distal spine, exopod with two external distal spines; very faint and unarmed suture on distal part of exopod.