1896.] 237 



ON PLAGITHMYSUS : A HAWAIIAN GENUS OF LONGICORN 

 ^ COLEOPTERA. 



BY D. SHAEP, M. A., P. E. S. 



The following sketch has been drawn up from the material re- 

 ceived by the Committee for investigating the fauna of the Sandwich, 

 or Hawaiian, Islands, and will give some idea of the extent of the work 

 done by Mr. Perkins at the entomology of the group ; and it will 

 also allow us to form some opinion of the adequacy or inadequacy of 

 his collections for the purpose of satisfactorily working out the ento- 

 mological fauna ; this genus being probably the one of considerable 

 extent in Coleoptera that is best represented as the result of Mr. 

 Perkins' labours. The number of species known is increased from 

 four or five to about five times one of those numbers ; certain species 

 being still inadequately elucidated. Of some of the species Mr. 

 Perkins has obtained fine series of four or five dozen specimens, an 

 achievement far beyond what I had hoped for when he went to the 

 islands ; but others are represented by only one or two individuals, and 

 I judge from this that other species may exist which have yet eluded 

 his observations ; indeed, I consider there are probably thirty good 

 species of this one endemic genus still existing in the islands. 



JPlagithmysus will, with its two cognate genera Clytarlus and 

 Callithmysus, form a separate group, Plagithmy sides, to be placed 

 between the Clytides and Anaglyptides of Lacordaire. This new 

 group is peculiar to the Hawaiian islands, and is distinguished by a 

 very curious character, viz., that there is no transverse folding of the 

 wings, which therefore project beyond the tips of the body ; at the 

 same time the elytra are extremely attenuated towards the apex, and 

 the tips of the wings being twice longitudinally plicate, continue the 

 outline. I believe this peculiarity will be found to be connected with 

 some important features in the natural history of the species, which 

 must be in some points very unusual, for the males have the abdomen 

 reduced in size to so great an extent that it forms merely a small 

 appendage to the rest of the body ; a condition which will, I believe, 

 not be found to exist, in so extreme a state of development, in any 

 other forms of Coleoptera. According to Mr. Perkins the manner of 

 pairing of the sexes is highly peculiar.* The mode of holding the 

 wings is correlative with a characteristic structure of the tips of the 

 organs, inasmuch as this part is provided with two thick, slightly 



See this volume previously, page 193, 



