FISHERY BULLETIN: VOL. 75, NO. 2 



Affinities. -Hadropenaeus lucasii is closely allied 

 to its two Atlantic congeners, H. affinis and H. 

 modestus, but it may be distinguished from them 

 by the possession of a conspicuous carina on the 

 rostrum dorsal to the adrostral carina, and by 

 certain petasmal and thelycal features. In H. 

 lucasii the ventromedian lobule of the petasma is 

 not produced into a distolateral projection; in- 

 stead, its lateral portion is turned strongly 

 inward; the distal plate of the ventrolateral lobule 

 bears spinules along the entire terminal margin 

 and is produced in a blunt, ventral projection; in 

 addition, the ventral costa falls conspicuously 

 short of the distalmost part of the adjacent plate. 

 The thelycum, in turn, is characterized by a 

 median protuberance on sternite XIV, which does 

 not project ventrally so far as the posterior convex- 

 ities of sternite XIII, and the latter bears a low 

 median ridge which is not produced anteriorly in 

 a large tooth. Furthermore, in females of H. 

 lucasii, the coxae of the fourth pair of pereopods 

 bear a conspicuous anteromesial spine which is 

 lacking in the other two species. 



Hadropenaeus lucasii exhibits some morpho- 

 logical variations which are undoubtedly taxo- 

 nomically insignificant because extremes of 

 variations occur in animals from the same region 

 and even from the same locality. Among them 

 are the relative extension of the scaphocerite, 

 gnathal and thoracic appendages, the total 

 number of rostral teeth as well as the number 

 situated on the carapace. The evidence at hand, 

 however, indicates that the ventral antennular 

 flagellum and some features of the petasma differ 

 regionally. The ventral antennular flagellum is 

 somewhat depressed in the holotype from New 

 Guinea, in Japanese specimens (Kubo 1949) and 

 in two specimens from Madagascar examined by 

 me, and subcylindrical in individuals from Indo- 

 nesia (de Man 1911) as well as in all those avail- 

 able from Hawaii. In addition, the distomesial 

 projections of the ventromedian lobules of the 

 petasma are larger in specimens from Japan than 

 in males from Madagascar and Hawaii. Whereas 

 the shape of the flagellum exhibits definite varia- 

 tions which seem to be regionally restricted, the 

 differences in the petasma are limited to degree 

 of development and are perhaps insignificant. 

 Except for the collection from Hawaii, available 

 material is extremely meager; consequently, the 

 variations that I have noted are pointed out, with 

 the conviction that definite conclusions as to their 

 taxonomic value must await examination of ade- 



quate collections from various areas throughout 

 the Indo-West Pacific. 



I have examined the female from the Maldive 

 Islands, Indian Ocean, that Ramadan (1938) iden- 

 tified as H. lucasii. This specimen differs from 

 other specimens of the latter species in the follow- 

 ing features: the rostral and epigastric teeth are 

 slenderer — not much stronger than the post- 

 orbital spine — and inclined more anteriorly; the 

 anteromesial spine on the coxa of the fifth pereo- 

 pod is longer and more slender; and the median 

 protuberance on sternite XIV is smaller and sur- 

 rounded by a shallow depression. Crosnier and 

 Forest (1973), who presented an illustration of 

 the thelycum of the specimen (plate 85, figure a), 

 suggested that the slight differences between the 

 thelycum of the latter and that of the type of H. 

 lucasii could be due to the difference in size of 

 the animals, the type being 90 mm long (23.5 mm 

 cl) and Ramadan's specimen 70 mm. As these 

 authors indicated, Ramadan's specimen exhibits 

 6 middorsal teeth (rostral plus epigastric), 3 of 

 which are located on the carapace; this number 

 and arrangement of teeth occurs infrequently in 

 members of H. lucasii, but has been observed in 

 several specimens by both Rathbun (1906) and 

 me. Crosnier and Forest suggested further that 

 because of the number and arrangement of the 

 middorsal teeth and the relative size of those 

 behind the rostrum (which are not much stronger 

 than the postorbital spine), Ramadan's specimen 

 might be referable to Borradaile's (1910) Hali- 

 porus malhaensis. This species was described from 

 Saya de Malha, Indian Ocean, and its identity is 

 still uncertain, primarily because the holotype, 

 the only specimen on which the description was 

 based, is no longer extant (Ramadan 1938). The 

 features pointed out above suggest that the 

 shrimp from the Maldive Islands might belong to 

 a species other than H. lucasii, but an under- 

 standing of its systematic position must await 

 more material from the Indian Ocean. 



Both Burkenroad (1936) and Ramadan (1938) 

 were inclined to think that H. malhaensis was 

 identical with H. lucasii, and placed the former 

 name in the synonymy of the latter preceded by a 

 question mark. Previously, de Man (1911) had 

 indicated that he would have identified them as 

 one species, except for Borradaile's statement that 

 in H. malhaensis neither the fourth nor the fifth 

 pereopod is "particularly slender." De Man also 

 called attention to the fact that in Borradaile's 

 illustration the propodi of the fourth and fifth 



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