Review of the flower-inhabiting water scavenger beetle genus Cycreon (Coleoptera, Hydrophilidae), with descriptions of new species and comments on its biology Author Arriaga-Varela, Emmanuel Author Wong, Sin Yeng Author Kirejtshuk, Alexander Author Fikacek, Martin text Deutsche Entomologische Zeitschrift 2018 65 1 99 115 http://dx.doi.org/10.3897/dez.65.26261 journal article http://dx.doi.org/10.3897/dez.65.26261 1860-1324-1-99 4B756F25162F4FDABE0460F397663847 Cycreon floricola sp. n. Figs 1 A-C , E-O, 2, 3 A-D , E-H , 4 G-I , 5 D-F , G-I , 6 A-B Description. Measurements. 2.2-3.4 mm long (length of holotype: 2.9 mm), 1.8 -2.0x as long as wide, widest at basal fifth of elytra; weakly convex, 3.1 -3.4x as long as high (height of holotype: 0.9 mm). Colouration. Light brown with darker elytra (Figs 1 A-C ). Head. Clypeus about 2.5 x as wide as long, with anterior margin of clypeus margin very weakly emarginate medially. Frons and clypeus with punctation composed of complete circular impressions (punctures) with one small setiferous puncture on anterior margin (Figs 4G, D). Interocular distance about 4.9 -5.2x width of one eye in dorsal view. Mentum (Figs 1J, 2B, 4K, 5E,H) subtrapezoid, widest at posterior fifth, about 2.1 x as wide as long, with deep emargination reaching beyond anterior third of mentum length; surface with sparse, moderately long setae in anterior half, posterior half glabrous, punctures moderately large and deep, becoming smaller mesally, with 2-3 punctures with ring-like impressions close to posterolateral angles. Prothorax. Pronotum transverse, widest at base, 2.2 x as wide as long; 1.5 -1.6x wider at base than at anterior angles , 1.6 x as wide as head including eyes. Punctation dense and shallow, consisting of semicircular to complete ring-like impressions with a small setiferous puncture on posterior margin (Figs 4E, H, 5F, I), punctation approximately same in size and density all over pronotum. Pterothorax. Elytra widest at anterior fifth, 1.1 -1.2x as long as wide, 2.9 -3.0x as long as pronotum, 1.1 x as wide as pronotum. Punctation on intervals composed of semicircular impressions with setiferous puncture on posterior margin (Fig. 4F, I). Legs. Metatibiae wide and flattened, very weakly curved, 0.35 x as long as elytra, 4.8 x as long as wide. Male genitalia. Median projection of sternite 9 (Fig. 3D, H) rounded apically, with few short subapical setae, shorter than lateral struts. Phallobase (Fig. 3C, G) about 0.8 x as long as parameres, asymmetrically narrowing towards base, manubrium acuminate and slightly hooked, with apex rounded. Parameres continuously narrowing from base to apex, but slightly widened at apex; external margins bisinuate; apex obliquely acuminate. Median lobe moderately wide (Fig. 3 A-B , E-F ), almost parallel-sided throughout, apex acuminate, with very acute tip, expanded basally and bent dorsally on lateral view, gonopore large, situated subapically. Etymology. The species name reflects the association of this species with flowers, it consists of flori- (from Latin flos, floris = flower) and -cola (from Latin incola = inhabitant). Comment. This species is composed of two phenotypically distinguishable forms which are geographically exclusive and are here descibed as subspecies. Morphological differences are mainly restricted to punctation on the pro notum , which consists exclusively of incomplete ring-like impressions in the mainland form ( C. f. floricola ssp. n.), and exclusively or mainly of the completely ring-like forms in the specimens from Borneo ( C. f. borneanus ssp. n.).