On the Occurrence of Paradella Dianae (Menzies, 1962) a Genus and Species of Sphaeromatidae (Isopoda, Flabellifera) in the Arabian Sea

Abstract

The species under consideration, has been obtained from the Bulleji coast, Karachi, among intertidal algae and mud. It is worth noting that all the species placed in the genus Paradella have been recorded from the Americas, the Marshall Islands and from the eastand westcoasts of Australia. In the Indian Ocean, P. dianae has been recorded only from Western Australia. The genus and species are now recorded for the first time from the Arabian Sea, Indian Ocean. The measurements given are the total lengths of the body along the midline from the anterior margin of the head to the posterior apex of the telson. Material examined. ? Bulleji near Karachi, Pakistan. Among the intertidal algae Ulvafasciata, Padina tetrastromatica, and Caulerpa racemosa on a mud bottom; collected in February 1984. 2 adult males, 5 mm; 4 subadult males, 3.1-4.99 mm; 5 ovigerous females, 3.3-4.2 mm; 18 non ovigerous females, 2.5-4.5 mm. Descriptive remarks. ? The present specimens correspond closely to the description and illustrations given by Harrison & Holdich (1982) except in some minor details. The adult male (fig. 1A) differs from the Australian specimens while it agrees with the Brazilian specimens (Pires, 1982: 53, figs. 21, 22) in having distinct transverse ridges on posterior margins of pereonites 5 to 7 and 2 pairs of slightly larger granules lateral to the submedian pairs of tubercles on the pleotelson. Antennae 1 and 2 have 11 and 16 segments in the flagella of the adult male instead of 12 and 13, respectively (Harrison & Holdich, 1982: 103). The Ara bian Sea specimens also have a granulated pleon (fig. 1A) while illustrations by Harrison & Holdich (1982, figs. 6a, q) show no granules. Pereopod 1 (fig. 1C) is robust, pereopods 1 to 7 with a simple accessory unguis. The endopod of pleopod 1 (fig. ID) is not so acutely produced as that of the Australian specimen figured by Harrison & Holdich (1982: 104, fig. 6j). The exopod of pleopod 3 (fig. IF) is with an articulation. The pleotelson of the ovigerous female (fig. 2A) is rather more granular than in the Australian ovigerous female (Harrison & Holdich, 1982, fig. 6q), and the submedian pair of tubercles has a tendency towards fusion but is not com pletely fused.