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A.C. CAMPBELL AND F.W.E. ROWE 



Fig. 4 a, Scanning electron micrograph of the abactinial surface of Patihella paradoxa from Wadi Haart, Sadh, Dhofar, Southern Oman. Scale bar: 5mm; 

 b, Scanning electron micrograph of the actinial surface of Patiriella paradoxa from Wadi Haart, Sadh, Dhofar. Southern Oman. Scale bar: 5mm. 



rufotincta. During the monsoon period, July-September, the middle 

 shore is richly cloaked with the green alga Ulva sp. and brown algae 

 develop on the lower shore. These growths are burnt off by Decem- 

 ber, and then the intertidal remains almost alga free until the next 

 south west monsoon. It is worth noting that perennial beds of the 

 kelp Ecklonia radiata have been recorded off Sadh head (Barratt et 

 al., 1986) approximately 5 km. to the south west of this site. 

 Ecklonia may actually occur much closer as fragments were found 

 washed up on the beach. 



Paratype 2 was collected on 5.12.86 at Raaha 2.5 km. west of 

 Wadi Ayn at 8 m depth on rocks amongst corals. This site faced south 

 south east and comprised a sandy cove bordered to the east by a ridge 

 of metamorphic rock sloping down to sand at 10 m. The rock ridge 

 was well covered with many scleractinian colonies, especially 

 Acropora sp. During the south west monsoon period this 'coral 

 garden' became completely overgrown with the brown alga 

 Sargassopsis zanardini. At the time of the collection the S. zanardini 

 growths had broken up and dispersed. No Ecklonia radiata was seen 

 growing in the immediate vicinity. 



Distribution. Known only from the type localities on the coast 



of Dhofar, southern Oman. 



Remarks. Based on arrangement and shape of skeletal plates and 

 their armament, paradoxa is without doubt congeneric with Patiriella 

 regularis, the type species of Patiriella. It differs from that species, 

 as with the majority of its congeners in the form of the radial 'field' 

 of abactinal plates, the high number of papulae per papular area and 

 absence of suboral spines. The absence of suboral spines is shared 

 with four species from the southern Australian coast. Of these P. 

 pannvipara is a small, precociously viviparous, pentagonal, cush- 

 ion-shaped star; P. brevispina and gunni have six, non-projecting 

 rays, and are more or less cushion-shaped and hexagonal in outline. 

 Additionally, these species differ from P. paradoxa in the increased 

 frequency of two spines on each of the proximal actinal intermediate 

 plates, and gunni possesses two subambulacral spines per 

 adambulacral plate. P. paradoxa may appear to be most closely 

 related to P. calcar, differing most obviously in having a more 

 delicate abactinal plating and armament and having 5 instead of 7- 

 1 1 short rays. Clearly the geographical isolation of paradoxa from 

 its congeners has resulted in the evolution of a combination of 

 characters which isolates it within the genus. 



