On some new species of Ancorabolidae Sars, 1909 from the Gulf of California: the genera Ceratonotus Sars, 1909, and Dendropsyllus Conroy-Dalton, 2003 (Crustacea, Copepoda, Harpacticoida)

Abstract. Two new species of two genera of the family Ancorabolidae, Ceratonotus elongatus sp. n. and Dendropsyllus californiensis sp. n., found at 1642 m and 1759 m depth, respectively, in the Southern Trough of Guaymas Basin, are described. Ceratonotus elongatus sp. n. was attributed to that genus by a series of character states of which the lack of dendroid dorsal processes on the P6-bearing somite and the presence of such processes on the first abdominal somite were definitive. This species was observed to be very close to Ceratonotus thistlei Conroy-Dalton, 2003 from the San Diego Trough, and can be separated by a number of traits of which the elongated sensilla-bearing dorsal tubercles on the second abdominal somite in the new species was definitive. Dendropsyllus californiensis sp. n. has been placed within that genus given the presence of four geniculate setae on P1EXP2 and one seta on P1ENP2, one inner seta on P3EXP3, and lack of inner armature on P4EXP3. Dendropsyllus californiensis sp. n. appears to be more closely related to Dendropsyllus thomasi Conroy-Dalton, 2003 and Dendropsyllus magellanicus (George & Schminke, 1998) on account of the spinulose nature of the basis of the maxilliped, the two-segmented P4ENP, and the fused condition of the P5 baseoendopod and exopod, and seems to be even more closely related to Dendropsyllus thomasi by the degree of development of the lateroventral processes of the cephalothorax. Dendropsyllus californiensis sp. n. can be separated from its congeners by the relative length of the first antennulary segment, relative length of the caudal rami, and by the armature formula of P3ENP2.