344 PROCEEDINGS OF THE NATIONAL MUSEUM voi . 93 



Genus HYLOCURUS Eichhoff 



Hylocurus Eichhoff, Berlin Ent. Zeitschr., vol. 15, pp. 133-134, 1871; Ratio 

 Tomicinorum, Mem. Soc. Roy. Sci. Liege, ser. 2, vol. 8, pp. 298-301, 1878 — 

 Blandfokd, Biologia Centrali-Americana, Insecta-Coleoptera, vol. 4, pt. 6, 

 pp. 220-225, 1898— Blackman, New York State Coll. Forestry Teehn. Publ. 16, 

 pp. 142-148, 1922; Techn. Publ. 25, pp. 186, 192, 1928.— Schldl, Rev. Ent., 

 vol. 10, p. 723, 1939. 



Micracis LeConte (in part), LeConte, Proc. Amer. Phil. Soc., vol. 15, pp. 368-369, 

 1s7<;.— Swaine, Canada Dept. Agr., Ent. Branch, Bull. 14. pt. 2, p. 83, 1918 — 

 Blackman, Mississippi Agr. Exp. Stat. Techn. Bull. 9, pp. 19-27, 1920. 



Genotype. — Hylocums elegans Eichhoff. (Monobasic.) 



The genus Hylocurus Eichhoff contains more species than any of 

 the other genera of Micracinae. Of these, 12 have been described 

 from the Nootropics and 11 species are found in continental United 

 States. Several of the species are known only from one sex, and the 

 secondary sexual differences vary so greatly in different species groups 

 that in some cases we cannot be certain of the sex without dissection. 

 This is not desirable when a species is represented by a single 

 specimen. 



Blandford believed that in the males the elytral interspaces "be- 

 come subcarinate as they approach the declivity, round which they 

 form a marginal series of teeth, carinae, or in one species, acute spines" 

 and the sides of the elytra may appear to diverge behind. "In the 

 female the elytra are regularly and strongly declivitous behind, . . . 

 with no marginal tubercles." This may be true of all the species he 

 treated, as it is of such northern species as parkinsonian Blackman, 

 and quadrispinosus Blackman and to a lesser degree of langstoni 

 (Blackman), but it is not true of rudis (LeConte), biorbis (Black- 

 man), bicomus (Blackman), harnedi (Blackman), spaJix Blackman, 

 and schwarzi Blackman. In these latter species the most readily 

 seen secondary sexual differences have to do with frontal characters 

 or with differences in the number, size, and arrangement of tubercles 

 on the face of the declivity. 



It would then appear that a key to the entire genus cannot be per- 

 fected until specimens of both sexes of all the species are available. 

 Until such time we must rely on Blandford's key to the Neotropical 

 forms and on the existing keys for the more northern species. The 

 three new species described herewith can be readily fitted into the 

 latter key (Blackman, 1928, loc. cit.). 



HYLOCURUS BICONCAVUS, new species 



Plate 29, Figube 1 



Very dark reddish brown, the pronotum subopaque, elytra shin- 

 ing; 2.22 mm. long, 2.82 times as long as wide; related to rudis (Le- 

 Conte), biorbis (Blackman), and bicomus (Blackman). 



