Calastacus laurentae, Ngoc-Ho, 2011

Ngoc-Ho, Nguyen, 2011, The genus Calastacus Faxon, 1893 in France with a new species from off Brittany (Crustacea, Decapoda, Axiidae), Zoosystema 33 (4), pp. 515-521 : 517-520

publication ID	https://doi.org/ 10.5252/z2011n4a4
persistent identifier	https://treatment.plazi.org/id/03E487E4-FFC5-FFF4-43E4-FD6C41E4FEDF
treatment provided by	Felipe
scientific name	Calastacus laurentae
status	sp. nov.

Treatment

Calastacus laurentae View in CoL n. sp.

( Figs 1 View FIG ; 2 View FIG )

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. GoogleMaps

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 GoogleMaps ; 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 View FIG ) slightly shorter than abdomen, laterally compressed, upper border rounded.Cervical groove weakly defined dorsally, very faint laterally. Rostrum( Fig.1B View FIG )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 View FIG ) 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 View FIG ) as in specimen MNHN Th 349.

Telson approximately 1.5 times as long as wide in specimen MNHN Th 349 ( Fig. 1G View FIG ), 1.70 times as long as wide in holotype ( Fig. 1C View FIG ) ; 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 View FIG ) globulous, hardly mobile.

Second article of antennal peduncle ( Fig. 1A, B View FIG ) 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 View FIG ) with large epipod.

Maxilliped 2 ( Fig. 2B View FIG ) with exopod, epipod partly broken.

Maxilliped 3 ( Fig. 2C, D View FIG ) 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 View FIG ) 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 View FIG ) much smaller than pereopod 1, unarmed, fixed finger and dactylus with small pectiniform setae on cutting edge.

Pereopods 3, 4, 5 ( Figs 1A View FIG ; 2F View FIG ) 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 View FIG ) and pereopod 1 ( Fig. 1D View FIG ) those of other appendages were not examined.

Female and male gonopores open on coxae of pereopods 3 and 5.

Pleopod 1 ( Fig. 2E View FIG ) two-articulated, proximal article long and slender, distal article larger with a small internal projection, no visible appendix interna.

Pleopod 2 ( Fig. 2F View FIG ) 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 View FIG ) biramous, exopod and endopod slender with long appendix interna.

Uropods ( Fig. 1G View FIG ) 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.