Platypilumnus jamiesoni, Forges, 1996

Richer De Forges, B., 1996, The Genus Plafypilumnus Alcock and Description P. jamiesoni n. sp. from New Caledonia (Crustacea, Decapoda, Brachyura) of, Records of the Australian Museum 48 (1), pp. 1-6 : 4-5

Platypilumnus jamiesoni n.sp.

Fig. 2B, 3A,B, 4A-C

Material examined. NEW CALEDONIA, BATHUS 2 cruise, station CP 741, 22°35.53'S 166°26.56'E, 700-950 m: 1 male HOLOTYPE, 26.2x 30.6 mm ( MNHN B 22730). Station ep 762, 22°18.86'S 166°09.78'E, 620-700 m, 16 May 1993: 1 male PARATYPE 18.6x 21.5 mm, 1 female PARATYPE 20.4x 25.2 mm ( MNHN B 22731). Station CP 764, 22°09.41'S 166°02.93'E, 560-570 m, 17 May 1993: 1 male PARATYPE 30.4x 35.4 mm; gonads sampled for sperm studies; MNHN B 22729 .

Description. Size small. Carapace very flattened, regions visible but little marked. Surface of carapace smooth, carrying gastric groove with gastric fossetts. Curved groove on either side of the cardiac region. Front prominent and rectilinear, bimarginate, with median concavity; superior border finely serrated. Ten or eleven denticles, of equal length, on each side of median concavity. Epistome straight, with granular anterior border ( Fig. 3B ). Superior border of endostome forming crest interrupted on each side by concavity. Short, oblique crest on endostome.

Antenna short well protected, only flagellum passing anterior border of carapace. Anterolateral border curved, bearing some teeth flanked by spinules; spinules small, numerous, sharp.

Posterolateral border straight with row of granules anteriorly. Sub-hepatic region inflated and finely granular. Eyes short, little visible dorsally, hooked spine on ocular peduncle. Infra-orbital border with row of small spines ending in strong tooth at inner angle. Chelipeds of different sizes (also for females and juveniles): right cheliped very large on adult male, as long as carapace length; propodus very enlarged and flattened, with carina on inferior border; fingers apically hooked with black of fixed finger extending onto distal part; carpus quadrangular with two strong teeth at internal angle and row of seven spines on external border, superior face being smooth; superior border of merus carries some proximal spines. Small cheliped spinulate, less inflated; external face and superior border of propodus bearing strong spines, fingers thin and grooved; carpus spinular on superior face with two stronger spines at internal angle; merus with some distal spines on superior border and line of strong spines on ventral face; 2-3 spines on ventral face of coxa of pereopod 1. Pereopods 2- 5 long and slender: merus with row of spinules on superior border and two parallel rows on inferior border; carpus and propodus with spinules only on superior border. Pleopods: as shown in Fig. 4 . Colour: In life carapace is entirely milky white, pereopods 2-4 are reddish-orange on carpus, propodus and dactylus.

Etymology: dedicated to Professor Barrie Jamieson in honour of his work on the phylogeny of Brachyurans using the ultrastructural morphology of sperm.

Remarks. By the finely denticulate front, P. jamiesoni resembles P. inermis , however P. inermis has a much stronger spine at the outer edges of each side of frontal lobe, and the denticulation is much stronger. On P. jamiesoni , the infra-orbital border is denticulated, whereas it is only granular on P. inermis . The anterolateral border of the carapace carries numerous small, evenly sized spines on P. jamiesoni n.sp., whereas on P. inermis these spines are fewer, stronger, and irregularly sized. The posterolateral border is practically smooth on P. jamiesoni n.sp., but has a line of granules and spinules on P. inermis . The meri of pereopods 2-5 are more slender and less spinulous on P. inermis than on P. jamiesoni .

Platypilumnus jamiesoni n.sp. differs from P. soelae by: the front being more finely spinular; the carpus of the large claw has only four spines on the external crest, whereas it is spinular and granular on the superior face of P. soelae ; the infra-orbital border has a row of serrated spines, while there are only some large spinules on P. soelae ; the black colour of the fingers is more extensive on P. jamiesoni than on P. soelae .

P. jamiesoni n.sp. lives on muddy bottom, in the upper bathyal zone, between 300 and 700 m depth.

Figures

Fig. 3. Platypilumnus jamiesoni n.sp., holotype. A, dorsal view; B, anterior part of the ventral view.

Fig. 4. Platypilumnus jamiesoni n.sp. male paratype 30.4x35.4 mm. A and B, first gonopod. C, second gonopod.