Four new species of the genus Rhopalophthalmus (Mysidacea: Crustacea) from the northwest coast of India Author Panampunnayil, S. U. Author Biju, A. text Journal of Natural History 2006 2006-10-18 40 23 - 24 1389 1406 http://dx.doi.org/10.1080/00222930600929301 journal article 10.1080/00222930600929301 1464-5262 4581324 Rhopalophthalmus cijayai sp. nov. ( Figures 53–64 ) Material Holotype : adult male (IOBC-0506-10-50-1999). Allotype : adult female (IOBC-0506 A- 10-50-1999). Dahej: (21 ° 40.00 9 –21 ° 43.30 9 N, 72 ° 29.45 9 –72 ° 32.00 9 E); November 1996 , nine adult males, 30 adult females, three immature males, nine immature females, and 478 juveniles . Figures 53–59. Rhopalophthalmus υijayai sp. nov. (male, unless indicated). (53) Anterior part of body. (54) Antennule. (55) Antenna. (56) Third thoracic endopod. (57) Fifth thoracic limb. (58) Eighth thoracic limb. (59) Eighth thoracic limb of female. Figures 60–64. Rhopalophthalmus υijayai sp. nov. (male). (60) First pleopod. (61) Second pleopod. (62) Third pleopod. (63) Telson. (64) Posterior part of body. Description General form slender. Carapace short, leaving last three thoracic somites exposed; anteriorly produced into broadly rounded rostrum covering basal one-quarter of antennular peduncle and basal part of eyestalks; two small dorso-median nodules present, postorbital spines small, cheeks sinuous. Eyes extending to distal end of first antennular segment, cornea occupying one-quarter of eye and little narrower than stalk ( Figure 53 ). Antennule robust in male, first segment as long as distal two segments combined and with row of 9–10 plumose setae on outer margin, outer distal corner produced and tipped with few setae; second segment short with two hooked setae on inner margin, outer distal corner produced and tipped with setae; third segment broad with one spinous seta on outer margin, four hooked setae on inner margin and five to six long plumose setae on inner distal angle; dorsal lobe tipped with few setae; base of outer flagellum swollen and densely hirsute ( Figure 54 ). In female antennular peduncle slender and longer, first segment longer than other two segments combined, hooked setae absent; third segment with seven long plumose setae on inner distal angle and four setae on inner margin. Antennal scale as long as antennular peduncle, 4.6 times as long as broad, outer margin straight, terminating in spine projecting beyond rounded apex, inner margin setose; antennal peduncle extending to middle of scale; antennal sympod with two long and two short spines on inner distal corner ( Figure 55 ). Mouthparts and first and second thoracic endopods as in R. mumbayensis . Endopods of third to seventh thoracic limbs slender, increasing in length posteriorly; propodus three-segmented in third and five-segmented in fourth to seventh endopods ( Figures 56, 57 ). Eighth endopod in male three-segmented, shorter than proximal segment of exopod, second segment short with three long plumose setae on outer distal corner, second segment long and finger-like with single simple seta at tip ( Figure 58 ). In female eighth endopod unsegmented with two simple setae and shorter than proximal segment ( Figure 59 ). Pleopods biramous and natatory. First pleopod with 10-segmented exopod; endopod unsegmented and short, sympod with three plumose setae on inner distal margin and row of long plumose setae along mid-dorsal line ( Figure 60 ). Second pleopod with 10- segmented endopod; exopod 13-segmented, segments increasing in length posteriorly, first five segments with usual pair of plumose setae, distal eight segments without setae, terminal segment ending in three long barbed setae, two at tip, one slightly away from tip ( Figure 61 ). Third to fifth pleopods in male similar, endopod and exopod 10-segmented. Pleopods in female simple, unsegmented and rod-shaped, distal pairs progressively increasing in length ( Figure 62 ). Telson 1.4 times longer than last abdominal somite, 2.3 times as long as maximum width at base, abruptly narrowing near base to form waist, lateral margins almost parallel up to distal half and gradually narrowing towards rounded apex and armed along distal half with seven slender subequal spines, distal margin with two pairs of long sub-equal spines, inner pair of spines with 12 and outer pair with 10 pairs of closely set subsidiary teeth, proximal teeth spiniform and distal teeth broader ( Figure 63 ). Uropods: exopod and endopod two-segmented, setose all round and longer than telson. Endopod with one strong spine on inner margin ( Figure 64 ). Length: adult male 6.6 mm , adult female 8.6 mm . Etymology This species is named in honour of Dr Vijayalakshmi R. Nair, Scientist (retired), NIO. Remarks This species can be easily distinguished from all the other species of the genus except R. africana O. Tattersall, 1957 by its slender form and in having fewer spines on the lateral border of the telson. In R. africana , the lateral margin of the telson is armed with six to eight spines only, but differs from the new species in having only two large spines on the antennal sympod, four carpopropodal segments in third to seventh thoracic endopods and in its more robust form. The largest male and female of R. africana measured is 10 and 10.2 mm , respectively, whereas the maximum size of the present species is only 8.6 mm . Ecological note The specimens were collected from depths between 8 and 25 m , where the bottom was silty sand, and occurred in temperatures and salinity ranging from 26.9 to 29.0 ° C and from 23.1 to 29.8 psu, respectively.