Crustacea Decapoda: Le genre Eumunida Smith, 1883 (Chirostylidae) dans les eaux néocalédoniennes

Abstract

[EN] The genus Eumunida, belonging to the family Chirostylidae, is represented in New Caledonia and Chesterfield Islands by seven species, all of them new to Science : Eumunida keijii, E. sternomaculata, E. annulosa, E. capillata, E. parva, E. minor and E. marginata. Four species (E. sternomaculata, E. annulosa, E. capillata, and E. parva) are very common at depths between 400 and 600 meters, being currentIy caught at the same stations. The other species are scarce, and have been collected either at the sarne depths (E. keijii), or in shallower waters (E. minor and E. marginata). The high abundanee of these speeies eould be related to the presence on the bottom of hydrocorallians of the family Stylasteridae. Three species (E. keijii, E. annulosa and E. sternomaculata) belong to the group A after GORDON (1930), characterized by a spine on either side of the sternal segment bearing the chelipeds. The latter two of these speeies have a pad on the ventral surface of the palm. E. keijii is dosely related to E. pacifica Gordon, 1930, from the south of Timor, but, among other differences, the two are readily distinguished by the size of the first hepatie spine, the median sinus of the third thorade sternite and the sea les on the sternal segrnents. E. sternomaculata resembles E. sp., from southeast Australia (E. picta, GORDON, 1930, in part) ; both are nevertheless easily distinguished by the shape of the frontal part of the earapace, the direction of the supraorbital spines and the relative lengths of the anterolateral spines and antennal pedundes. E. annulosa is dose to E. sternomaculata. These two species are differentiated by the shape of the rostral spines, the ornamentation of the carapace, the length and shape of the chelipeds and the presence or absence of a disto-mesial spine on the carpus of the chelipeds. E. marginata, E. capillata, E. parva and E. minor belong to the group B, after GoRDON, that has no spine on either side of the sternal segment bearing the chelipeds. With the exception of E. parva, all the other species are provided with a pad on the ventral surface of the palm. E. parva is dosely related to E. smithii Henderson, 1883, from the south of Timor, and to E. propior Baba, 1988, from the Philippines. A diseussion about the identity of the material of E. smithii from different expeditions and the relationships between the three species is provided. The males of these three species are characterized by the presence of pleopods on the second to fifth abdominal segments. E. capillata is very dose to E. parva, but can be easily distinguished from it by a number of characters. The main difference is the presence of a pad on the ventral surface of the eheliped palm in capillata, and its absence in parva. E. minor is the smallest representative of the genus. The species is c1early distinguishable from al! the others of the group B by the presence of two prominent spines on the merus of the third maxilIipeds, and of four longitudinal rows of spínes on the merus of the chelíped. Its c10sest relatíve is E. balssi Gordon, 1930. E. marginata is related to E. gordonae Baba, 1973, from Japan. However, the length and the spinulation of the pereopods are very dífferent

[FR] Le genre Eumunida, Galatheidea Chirostylidae, est représenté au large de la Nouvelle-Calédonie et dans I'arehipel des Chesterfield par sept esperes au moins, toutes déerites eomme nouveHes. Eumunida sternomaculata, E. annulosa, E. capillata et E. parva apparaissent eomme tres eornmunes entre 400 et 600 metres, et ont souvent été réeoltées aux memes statíons. Les troís autres ne sont représentées que par un petit nombre d'individus: quatre pour E. keijii, reeueillie sur les memes fonds que les précédentes, sept pour E. minar sp. nov., réeoltée de 230 a 274 metres, et un seul pour E. marginata, proehe d' E. gordonae Baba, 1976, provenant de 330 métres. La deseription des espeees est complétée par leur comparaison entre elles et avec les autres espeees indoouest- pacifiques du genre. Quelques indications sont données sur le développement des Eumunida, qui, a l'inverse de celui des autres Chirostylidae ou il est connu, comprend une phase pélagique, analogue a ceHe de nombreux autres Décapodes. L'abondance exceptionnelle des Eumunida dans la région étudiée pourrait etre liée à celle, également remarquable, des Hydrozoaires de la famille des Stylasteridae