ARE ATYA SPINIPES NEWPORT AND ATYA ARMATA 



MILNE EDWARDS SYNONYMS FOR ATYA 



MOLLUCCENSIS DE HAAN? 



By R. P. CowLES 



{From the Department of Zoology, College of Liberal Arts, 



University of the Philippines) 



ONE TEXT FIGURE 



In 1868 Eduard von Martens ^ stated that he had received 

 several specimens of the genus Atya from the Philippine Islands. 

 The specimens differed from one another in the size and arma- 

 ture of the third legs and in the body length, but they were 

 otherwise similar, and von Martens reached the conclusion that 

 they were all of the same species. The largest specimen agreed 

 with Atya armata Milne Edwards,- collected in the Philippines, 

 and described as having a long heavy spine on the lower border 

 of the merus of the third leg. However, von Martens's smaller 

 specimens agreed with the description of species of Atyoida in 

 which the third legs are but slightly larger than the fourth 

 and fifth and in which there is only a weak, slender, and incon- 

 spicuous spine on the merus. Specimens intermediate in size 

 showed gradations from the large third legs with the heavy 

 spine to the small third legs with the weak inconspicuous 

 spines. As a result of his observations von Martens rightly 

 discarded the genus Atyoida, considering the specimens upon 

 which it was based as the young of some species like Atya 

 armata. 



Recently I have collected atyas from a mountain stream near 

 Manila and have obtained a series similar to that of von Mar- 

 tens's. The largest males agree very well with the description 

 of Atya armata except that the lower margin of the rostrum is 

 toothed, a fact which has been observed by Bouvier. In a series 

 arranged according to the body length, the third legs grade in 

 size from a condition found in the largest males, where they 

 are much larger than the fourth and fifth legs, to a condition 

 found in the small males, where they are of about the same size 

 as the fourth and fifth legs. The graded reduction in the size 



^Arch.f. Naturgeschichte (1868), 34. 47. 

 -Ann. Soc. ent. France (1864), 33. 47. 



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