Papers in Marine Biology and Oceanography, Suppl. to vol. 3 of Deep-Sea Research, pp. 134-138. 



The specific characters of the coral Sty/aster roseus 



By H. BoscHMA 

 Rijksmuseum van Natuurlijke Historic, Leiden 



In the collections brought together by Dr. P. Wagenaar Hummelinck in the Leeward 

 Islands and other parts of the West Indian region there are a few small colonies of a 

 stylasterine coral with the following data: Curasao, Plaja Djerimi, North corner, 

 December 11, 1948 (rock, sand; tidal and lower zone). Examination of these corals 

 showed that in all their salient characters they prove to correspond with Stylaster 

 roseus (Pallas) as far as the eighteenth-century data on the species are concerned, 

 while differing from the specimens identified with this name in recent literature. 



The corals from Curasao are four or five colonies of a more or less fan-shaped 

 growth, occurring together on a fragment of dead coral rock. The colonies are up to 

 3 cm high and not over 3 cm broad. Each colony consists of a few stems of a breadth 

 of about 5 mm, rapidly tapering upwards while giving off side branchlets which in 

 their topmost parts have a thickness of about 1 mm. The stems and the thicker 

 branches are slightly compressed in the flabellar plane of the colony. On the upper 

 parts of the branchlets the cyclosystems occur alternately on the two lateral surfaces, 

 whilst on the thicker branches the cyclosystems are distributed without apparent order; 

 they are more numerous on the anterior than on the posterior surface. The number of 

 dactylopores in the cyclosystems varies from 7 to 12; this number was counted in 100 

 cyclosystems with the following result: 5 cyclosystems with 7 dactylopores; 12 with 

 8; 28 with 9; 37 with 10; 14 with 1 1 ; 4 with 12; yielding an average of 9-55. 



Except on the tops of the smaller branchlets the cyclosystems extend very little 

 above the surface of the coral; their diameter varies from 0-5 to 0-7 mm. The gastro- 

 pores have a depth of about 1 mm, and the gastrostyles have a length of 0-4 mm and a 

 thickness of 0-15 mm, so that they are rather slender, occupying about one-third to 

 one-half of the lower part of the gastropore (Fig. lb). The gastrostyles are covered 

 with small spines on the whole of their surface (Fig. la). Feebly developed dactylo- 

 styles (not drawn in Fig. lb) are present in the dactylopores. 



The colonies bear numerous ampullae of a hemispherical shape, scattered among 

 the cyclosystems on the larger branches, or occurring in clusters densely covering 

 large parts of the surface; as a rule the ampullae are numerous, especially on the 

 posterior surface of the colonies. The ampullae have a smooth surface, without warts 

 or spines, and their diameter varies from 0-6 to 0-8 mm, the size indicating that 

 probably they are female ampullae. 



The colour of the corals from Curasao is yellowish with an irregular admixture of 

 pink, occasionally turning to a light purplish tint in the topmost parts of some branch- 

 lets or on and around some cyclosystems on the larger branches. 



Pallas (1766) gave a description of the coral named by him Madrepora rosea, 

 mentioning some characters which at present still may be regarded as typical of the 



134 



