THE BRITISH SPECIES OF THE GENUS PHILYDKUS, SOLIER. 



25 



On the British Species of the genus Philydrus, Solier {iritli idate). 



By FRANK BALFOUR-BROWNE, M.A. (Oxon.), F.R.S.E., F.Z.S. 



The genus Philydrus or P/iillii/dnis, is represented in Britain by 

 six species, which are described by both Fowler and Ganglbauer as 

 divisible into two groups, testareus, F., inaritimi(s, Thorns., nvpicans, 

 Zett., and inelanoce/i/ialns, 01., belonging to the one group, the subgenus 

 I'ltili/ili-Ks, s. str. ; minuttta, F., and coatrtatns, Gredl., to the other, the 

 subgenus Methi/drKs, Rey or Afiio/ihilj/ibits, Kew. 



1 have recently been critically examining these six species, and the 

 following notes are the outcome of this examination, written partly 

 because the characters for separating the species as given by Fowler 

 ai'e to some extent unreliable, and partly because it appears to me that 

 tlie position of the species niflvicans, Zett., in the same subgenus as 

 tt'stareus, maritinixs and melanncephaluH is not satisfactory, considering 

 the character, as given by Fowler" and Ganglbauer f, upon which the 

 group is based. This character is the presence at each side of the 

 thorax of a number of large punctures arranged more or less in the 

 form of a crescent. Fowler se})arates off this group sharply from the 

 other, which he describes as having " thorax without larger punctures 

 at sides," but Ganglbauer more accurately says that there may be at 

 each side of the thorax in ininntHs and coarctatas a few somewhat 

 larger punctures. 



Now this series of punctui'es is quite distinct in testaceiis, ))iariti)m(S 

 and tiu'lanncephalus, but in nitjricmu it is much less marked. Large 

 punctures are undoubtedly present in many specimens, if not all, of 

 iiiinutiis and coarctatus, and in some specimens the series is as distinct 

 as in some specimens of niffrirons. It was this point which first caused 

 me to carefully examine the species. 



Fowler does not mention the fact that the tarsal claws of the males 

 of the species have a distinct protuberance or tooth on the underside, 

 while Ganglbauer mentions the character but makes no use of it in 

 separating the species. For my purpose it is sufficient to refer to the 

 tooth on the anterior claw of the anterior tarsi. In testaeeiis, uuiritiiinis, 

 and melanncephaliis this tooth is particularly well-marked and is trans- 

 rrrsfli/ striated, as can be seen by removing the claw and examining it 

 by transmitted light under a microscope of moderate power. In 

 II i II r leans there is also a tooth to this claw, rather smaller than in the 

 other three species, but there is«rj transverse striation. In niijiKtiis and 

 roiiretatus again the tooth is very much smaller and shows no sign of 

 transverse striation. A glance at the figures given will show the 

 diffei'ence in the species. 



In testaceus, maritimns, and melanncephalus the elytra show indistinct 

 traces of three rows of larger punctures and the fact that iriifricans does 

 not show these striae, I is used both by Ganglbauer and by Fowler for 

 separating this species from the other three. In this character again 

 we find niiiricans agreeing with miuiitns and cnarctatits where no trace 

 of the striae is visible. 



Xii^ricans, therefore, seems to me to be sufficiently distinct from 

 tcstart'Ks, uiaritiiniis, and nielamicephalus, to warrant its removal from 



* Fowler, W. W., Coleoptera of the British Islands, 1887, vol. i., p. '223. 

 t Ganglbauer, L., Die Kiifer von Mitteleuropa, 1904, vol. iv., pt. 1, p. 244. 

 + In some specimens a few larger punctures are to be found. 

 February 15th, 1908. 



