Himalayacaris alaknanda n. gen., n. sp. (Copepoda: Harpacticoida: Parastenocarididae) from the hyporeic zone of a Himalayan River, northern India

Abstract

We establish Himalayacaris n. gen. to accommodate the type and only species, Himalayacaris alaknanda n. sp., collected in the Himalayan Alaknanda River, Uttarakhand, northern India. This species displays three principal autapomorphies of the male leg 4, which are considered diagnostic for the genus: 1) the enormous, conical, plate-like modified structure at the proximal inner corner of the coxa, bearing hair-like spinules at inner distal margin; 2) the condition of the endopod, a small, unornamented, plate-like structure ending in a tiny papilla fused to the basis; and 3) the short and somewhat modified first exopodal segment, ornamented with an additional row of obliquely directed spinules on its dilated inner margin. Another unique feature of this species is the row of long spinules on the proximal inner margin of the basis of the male leg 2. Himalayacaris is closely related to the Neotropical Remaniecaris Jakobi, 1972, but differs from it, inter alia, in the details of the setae of the caudal rami, ‘pocket knife type’ of the male antennules, the shape of the basis and the configuration of the exopod and endopod of male leg 3, the insertion of the outer spine of the third exopodal segment of male leg 4, the absence of additional ornamentation of endopod of the male leg 4 and the configuration and armature of leg 5. This is the first hyporheic species from the Ganges River system in the Garhwal Himalayas and the second one from the Himalayan rivers. The phylogenetic position of the new taxon within Parastenocarididae is discussed. In addition, a brief note is given on the ecology of the new species, especially on its skewed sex ratio resulting from the scarcity of males (spanandry), and also on its biogeography.