Abstract
A species in the marine water mite family Pontarachnidae is newly described under the name of Litarachna sagamiensis sp. nov. This species is found in intertidal algae in Sagami Bay on the Pacific coast of Japan. The present new species is characterized by the following: (1) The right and left first coxal plates are separated from each other; (2) the ventral tubercles on the second segment of palp is absent; (3) the ventral tubercle on the fourth segment of palp is present; (4) the ventral glandularium is separated from the first ventral platelet; (5) the ventral glandularium and ventral platelet are located posteriorly to the posterolateral apodeme of fourth coxal plate; (6) the posterolateral apodeme is slender; (7) three pairs of wheel-like acetabula are present in the female; and (8) 49 perigenital setae are present in the male. Litarachna sagamiensis sp. nov. resembles L. duboscqi, L. hongkongensis, and L. marshalli in general morphology, but the new species differs from the latter three species by the condition of the ventral glandularium, the positions of the ventral glandularium and the first ventral platelet, the number of wheel-like acetabula in the female, the shape of the distal margin of medioposterior apodeme in the male, and the number of perigenital setae in the male. This is the third species in the genus Litarachna described from Japan.
