Laccobius (Cyclolaccobius) hainanensis, Jia, Fenglong, Gentili, Elio & Fikáček, Martin, 2013

Jia, Fenglong, Gentili, Elio & Fikáček, Martin, 2013, The genus Laccobius in China: new species and new records (Coleoptera: Hydrophilidae), Zootaxa 3635 (4), pp. 402-418 : 406-408

Laccobius (Cyclolaccobius) hainanensis sp. nov.

( Figs. 8–13 )

Type locality. China, Hainan Island, Limushan Mts., 19°9.1–9.2ʹN 109°45–46ʹE, 550–750 m a.s.l.

Type material. Holotype: ♂ (SYSU): China: Hainan Isl. [MF 18] / Limushan Mts., 5.v.2011 / 19°9.1–9.2ʹN 109°45–46ʹE / 550–750 m; along the road / Fikáček & Zhao lgt. // seepages with thin algae / layer + nearly bare wet rock / without distinct algae along / most remote end of road. Paratypes (32): 31 spec. (SYSU, NMPC, MSNV): same data as holotype; 1 male (MSNV): China, Hainan Prov. / Limushan, Limu Temple / 5.v.2011, Shuan Zhao leg.

Description. Total length 1.8–2.1 mm (holotype 2.0 mm); maximum width 1.2–1.4 mm (holotype 1.3 mm). Total length / total width ratio = 1.5. Body oval, moderately convex, with greatest width in anterior third of elytra, continually narrowing more posteriad.

Head. Labrum black, without specula in both sexes, slightly convex on anterior margin, closely adhering to clypeus; surface densely punctured, anteriorly with stiff setae. Clypeus and frons shiny black, preocular pale spots extremely small and vague; surface with irregular, scarcely arranged fine punctures, punctures slightly impressed but larger than labral punctures, each puncture with decumbent seta; microsculpture absent. Clypeus nearly 1.5× as wide as long, deeply emarginate anteriorly; frontoclypeal suture scarcely distinct. Eyes transversely oblique, nearly 2.5× as large as long, reniform posteriorly, closest to each other posteriorly than anteriorly; minimum interocular distance in frontal view 2.2× of width of one eye. Ventral surface black, except the brown maxillae. Mentum flat, uniformly microreticulated, with scarce punctures. Postmentum smooth, gula granulate. Maxillary palpi yellowish; palpomere 3 inflated, palpomere 4 asymmetrical, straight medially and convex laterally, scarcely infuscate at extreme apex. Antennae with 8 antennomeres, yellowish with darker club; scape (antennomere 1) longer than antennomeres 2–4 combined, pedicel (antennomere 2) cone-shaped, two intermediate antennomeres (antennomeres 3–4) very short, cupule (antennomere 5) asymmetrical, oval ventrad, crescent-shaped and emarginated dorsad, antennomere 7 expanded, larger than remaining club antennomeres, antennomere 8 constricted near apex.

Thorax. Pronotum black, laterally with a yellowish irregular band widening posteriorly, external borders slightly explanate; microsculpture absent, punctation consisting of fine sparsely arranged setiferous punctures, only with irregular serial arrangement of punctures along margins. Prosternum with narrow longitudinal carina. Scutellar shield equilaterally triangular, black, impunctate. Mesoventrite with longitudinal keel, anteriorly forming a beak. Elytra combined ca. as long as wide (i.e., elytral index = 1.0), black or dark on disc, yellowish along lateral margins, lateral pale stripe slightly widening anteriorly, more widening posteriorly, very narrow at midlength. Elytral punctation consisting of fine setiferous punctures arranged in ca. twenty longitudinal rows, with alternating series of larger and denser punctures (primary rows) and more irregularly distributed finer punctures (secondary rows). Parasutural stria absent, fifth elytral row slightly sulciform ( Fig. 8 ). Microsculpture absent. Lateral margins of elytra slightly explanate with a narrow bead. Epipleuron ending at level of metafemora. Metaventrite with decumbent pubescence, which is absent from a small medioposterior area.

Legs. Trochanters dark brown, femora dark brown except apical part, tibiae and tarsi yellowish brown. Femora pubescent basally, metafemur with coarser setiferous punctures. Tibiae with ranges of spines more developed on outer margin and on mesotibiae, metatibiae curved. Tarsal natatory setae nearly absent. Legs with five tarsomeres; protarsomere 5 nearly 3× as long as other protarsomeres; mesotarsomeres 2 and 5 each nearly 2× as long as other mesotarsomeres; metatarsomeres 1 and 2 each longer than other metatarsomeres. Claws shorter than tarsomere 5, arcuate.

Abdomen. Ventrites nearly smooth, sparsely pubescent; ventrite 5 and 6 wrinkled, pubescence denser on ventrite 6 than on ventrites 1–5.

Aedeagus. Total length 0.45 mm. Parameres nearly 1.5x as long as phallobase. Phallobase 1.3x as long as wide ( Figs. 10–12 ). Parameres slightly narrowing from base to apex, lateral and medial margins very slightly arcuate; distance between lateral margins of phallobase slightly wider than distance between lateral margins of parameres; apex of parameres asymmetrical, obtusely pointed. Median lobe as long as parameres, conically narrowing from base to midlength, then widened, conspicuously narrowing to wide subdivided apex (hence the apex lanceolate in shape).

Differential diagnosis. Laccobius hainanensis sp. nov. is very close to L. politus Gentili, 1979 , but may be distinguished from it by the wide lateral pale stripe on elytra suddenly widening near the elytral apex (more or less uniformly wide in L. politus ), the elytral puncture rows more conspicuous (scarcely evident in L. politus ), fifth elytral row slightly sulciform (not sulciform in L. politus ), the primary elytral puncture rows conspicuously setiferous (setae inconspicuous or barely conspicuous in L. politus ), the median lobe constricted subapically, weakly narrowing apicad (indistinctly constricted subapically and widely rounded at apex in L. politus ), and parameres wider, flat (not rod-like) and with pointed apex (parameres narrower and widely rounded apically in L. politus ).

The Chinese species of the subgenus Cyclolaccobius may be identified according to the following key (modified from Gentili 1995, 2003):

1. Elytral punctures irregularly arranged, scattered; body length over 3 mm .......................................... 2

- Elytra with longitudinal rows of punctures; body length under 3 mm ............................................. 3

2. Body blackish, convex in lateral view; head and pronotum smooth; male with specula; parameres longer than median lobe. 3.4–4.3 mm ..................................................................... L. zugmayeri Knisch, 1910

- Body testaceous, depressed in lateral view; head and pronotum shagreened; male without specula; parameres shorter than median lobe ( Fig. 26 ). 3.0– 3.2 mm ................................................ L. hingstoni Orchymont, 1926

3. Elytral base with a small yellow spot; median lobe longer than parameres, swollen in the basal half, narrow in apical half. 1.8–2.0 mm................................................................... L. yunnanensis Gentili, 2003

- Elytral base entirely dark................................................................................ 4

4. Body length 2.0– 2.8 mm. Elytral rows with punctures larger, very conspicuous at 40× magnification. Median lobe narrow throughout, narrower than parameres in its whole length..................................... L. nitidus Gentili, 1984

- Body length 1.8–2.1 mm. Elytral rows of punctures hardly conspicuous at 40× magnification. Median lobe widened at base and near apex......................................................................................... 5

5. Elytral primary puncture rows conspicuously setiferous at 100×; fifth row slightly sulciform. Elytral pale lateral strip constricted at midlength, then abruptly widening near elytral apex. Median lobe constricted subapically, weakly narrowing apicad................................................................................. L. hainanensis sp. nov.

- Elytral primary puncture rows not or scarcely setiferous at 100×; fifth row normal, not sulciform. Elytral pale lateral strip uniformly wide, only widening near elytral apex. Median lobe indistinctly constricted subapically, widely rounded at apex........................................................................................ L. politus Gentili, 1979

Biology. The type specimens were collected on a seepage and wet rocks along a road through secondary tropical forest. The habitat contained patches with a thin algae layer as well as areas of wet rock without any apparent algae.

Etymology. The species name refers to Hainan Island and Province, where the species was collected. Distribution. Hainan Island. Known only from the type locality in Limushan Mts. in central Hainan.

Figures

FIGURES 8 – 16. Laccobius hainanensis sp. nov. sp. nov. (8 – 13) and L. politus (14 – 16). 8 – 9: general habitus (8: dorsal view, 9: lateral view). 10 – 12: aedeagus (10: dorsal view, 11: lateral view, 12: ventral view). 13: habitat at the type locality of L. hainanensis. 14 – 16: aedeagus of L. politus from Yunfeng Shan Mt. in Yunnan (14: dorsal view, 15: lateral view, 16: ventral view).

FIGURES 20 – 26. Laccobius hammondi (20 – 25) and L. oscillans (26). 20 – 21: general habitus (20: dorsal view, 21: lateral view). 22 – 24: aedegus of L. hammondi (22: dorsal view, 23: lateral view, 24 ventral view). 25 – 26: aedeagus with open parameres showing the shape of the median lobe (25: L. hammondi, 26: L. oscillans from Japan, Sapporo env., Kimotetsu).