Arriaga-Varela, Emmanuel, Wong, Sin Yeng, Kirejtshuk, Alexander & Fikacek, Martin, 2018, Review of the flower-inhabiting water scavenger beetle genus Cycreon (Coleoptera, Hydrophilidae), with descriptions of new species and comments on its biology, Deutsche Entomologische Zeitschrift 1, pp. 99-115: 103
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Cycreon adolescens sp. n. Figs 1D, 3 I–J, 4J, 5 A–C
Malaysia, Pahang, Genting Highland [ca. 3.4233°N, 101.7930°E].
Holotype (male, teneral specimen): "Malaysia, PAHANG / Genting Highland / 24.X.2012 / H. Takizawa" ( IBTP). Paratypes: MALAYSIA: Pahang: [same data as holotype] (2 females: NMPC, KMNH).
Additional material examined.
MALAYSIA: Pahang: Cameron Highlands, Tanah Rata, Robinson Waterfall [ca. 4.461778°N 101.38803°E], in flowers of Araceae , 15.iii.2015, H. Takizawa lgt. (5 females: EIHE, KMNH, NMPC).
This species is most similar to Cycreon floricola borneanus ssp. n. in the very weakly emarginate anterior margin of the clypeus and pronotal punctation consisting of circular punctures, and straight meso- and metatibiae. It differs from the latter in the structure of the male genitalia (relatively longer phallobase and widely pointed apex of the median lobe) and by the less transverse mentum (1.7 × wider than long), with many ring-like impressions in posterior half.
Measurements. 2.4-3.0 mm long (length of holotype: 2.8 mm), 1.7 × as long as wide, widest at basal fifth of elytra; weakly convex, 3.3 –3.5× as long as high (height of holotype: 0.82 mm). Colouration. Light brown with slightly darker elytra (Fig. 1D).
Head. Clypeus about 2.4 × as long as wide, with anterior margin of clypeus margin very weakly emarginate medially. Frons and clypeus with punctation composed of complete circular impressions (punctures) with a small setiferous puncture on anterior margin (Fig. 4A). Interocular distance about 5.5 × the width of one eye in dorsal view. Mentum (Figs 4J, 5B) subtrapezoid, widest at posterior fifth, about 1.7 × wider than long, with a moderately pronounced emargination reaching about the anterior fifth of mentum length; lateral angles weakly marked; surface with few sparse, moderately long setae in anterolateral angles, posterior half glabrous, punctures moderately large and deep, vanishing mesally, 11-13 punctures close to posterolateral angles with ring-like impressions (punctures).
Prothorax. Pronotum transverse, widest at base 2.2 × wider than long; 1.6 × wider at base than between anterior angles, 1.7 × wider than head including eyes. Punctation dense and shallow, consisting of circular impressions with one small setiferous puncture on posterior margin (Fig. 4B), punctation of approximately same diameter and density all over pronotum.
Pterothorax. Elytra widest at anterior fifth, 1.1 –1.2× as long as wide, 2.9 –3.0× as long as pronotum, 1.2 –1.3× as wide as pronotum. Punctation on intervals composed of semicircular impressions with a setiferous puncture on posterior margin (Fig. 4C). Legs. Metatibiae wide and flattened, weakly curved on external margin, 0.35 × as long as elytra, 5.0 × as long as wide.
Male genitalia (Fig. 3 I–J). Phallobase about 1.1 × as long as parameres, slightly asymmetrical, manubrium slightly hooked, widely rounded. Parameres continuously narrowing apically, external margins straight, apex rounded. Median lobe wide throughout, apex triangularly acuminate, gonopore rather small, situated subapically. Median projection of sternite 9 not examined.
The species name reflects the teneral condition of the holotype (from Latin adolescens = growing up, maturing).
The species is only known two localities in Pahang province, Malaysia.
No details about collecting circumstrances are available for type specimens; additional specimens from Tanah Rata were collected from inflorescences of Araceae (H. Takizawa, pers. comm. 2018).
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