198 



INSECTS OF SAMOA. 



Another example before me has " Samoa " on the locality label, and also 

 bears a label with the word " Orthaulaca " on it in Weise's handwriting. 

 Type in the British Museum. 

 Described from eleven examples. 



The coarser punctuation and general rough sculpturing of the elytra dis- 

 tinguish this species from all other similarly coloured ones known to me. 



Plesistia, gen. nov. 



Body subcylindrical, oblong, with rounded apex ; subopaque, head and 

 pronotum apparently somewhat more shining. Antennae extending to about 

 middle of elytra, first and fourth segments long. Prothorax a little more than 

 twice as broad as long, with rounded sides ; the anterior and posterior lateral 

 angles are rounded right angles, each bearing a fine seta ; upper surface uneven 

 with smooth shallow depressions, very sparsely punctate. Scutellum pubescent. 

 Elytra parallel-sided, and each with ten ribs including a short scutellar one, 

 suture raised ; each alternate rib more strongly raised than the others, so that 

 there are four strong and five weak ribs on each elytron ; scutellar rib weak ; 

 intervals between ribs irregularly punctate. Under side hairy ; anterior 

 coxal cavities completely closed behind (see Text-fig. 10) ; legs strong, upper 

 surface of tibia with a fine rib, under side rounded, and apex without a spine. 

 Claws strong, with an angulate projection at base on under side (see Text-fig. 11a). 



Genotype : Plesistia brunnea Maulik. 



Range : Samoa. 



Relationship. — The new genus described above is related to Pleronexis Weise 

 (Nova Guinea, v, Zool., p. 321, 1908) in that both possess ribs on the elytra and 

 hairs on the scutellum. In Plesistia the anterior coxal cavities are closed behind 

 (see Text-fig. 10), while according to Weise they are open in Pleronexis. Through 

 the courtesy of Dr. J. B. Corporaal, however, I have had the opportunity of 

 examining Weise's type, and I find that the anterior coxal cavities are not open 

 behind. The closure of the coxal cavities in Pleronexis is of the same type as in 

 Plesistia. The difference between the two genera lies in the fact that in Pleronexis 

 all the ribs on the elytra are equally raised, while in Plesistia a strongly raised 

 rib alternates with a less elevated one. As regards geographical distribution 

 the two genera are alike. 



