Laccobius (Microlaccobius) hammondi Gentili, 1984

Liu, Hsing-Che & Fikáček, Martin, 2021, Review of the Taiwanese Laccobius Erichson, 1837 (Coleoptera: Hydrophilidae) with description of a new species, Zootaxa 4963 (3), pp. 587-599 : 591-592

Laccobius (Microlaccobius) hammondi Gentili, 1984 úẍ德flǿ牙ḃ

( Figs 12, 16 , 20 , 24 )

Laccobius (Microlaccobius) hammondi Gentili, 1984: 31

Laccobius (Microlaccobius) hammondi Gentili (1989: 39) (records from Taiwan).

Material examined. TAIWAN: MIAOLI: 1 male, ( NMNS): Shihyan, Chuanming Farm , 21-22.VIII.2000. S.H.Ku, UV light, [specimen NMNS ENT 3443-165 ] . NANTOU: 13 spec. ( NMPC): Heshe, Xinyi Township Tongfu Village, at bridge over Heshexi 23.58767°N 120.89027°E. 16.V.2018. Fikáček, Hu, Liang, Liu & Minoshima, lgt. (2018- TW35a) ; 2 males, 4 females, ( NMNS): Jenai, Meifeng , 7-8.VI.1998. C.S.Lin & W.T.Yang, UV light, [specimens NMNS ENT 2948-82 , 2948-120 , 2948-268 , 2948-412 , 2948-468 , 2948-655 ] . NEw TAIPEI: 2 spec., ( NMNS): Wulai [Ḅ來], Tunghou , 3.VII.2011. Y.-T.Wang leg. ; 1 male ( NMPC): Wulai City at Wulai Bridge , 24.86404°N 121.5518°E ,

18.v.2018, in gravel at sides of Tǒnghòuxî river just above Wulai Bridge, Fikáček & Minoshima lgt. (2018-TW09). YILAN: 3 females, ( HCLC): Jiaoxi Township [ẽëė], 24.828770°N 121.752787°E, 44m , 2.VII.2019. H.-C. Liu & F.-S. Hu leg. TAICHUNG: 1 male, 12 spec., ( HCLC): Qingtonglin [û桐ẇ] , 31.I.2019. Hsing-Che Liu leg.; 1 male, ( HCLC): Wufeng District, Qingtonglin Ecological Park [û桐ẇlDz公園], 24.048625°N 120.784559°E, 330m , 26.V.2019, Hsing-Che Liu leg.; 45 spec., ( HCLC): Wufeng District , 15.V.2019, Hsing-Che Liu leg. by uv light trap.; 9 spec. ( NMPC): Heping distr,, Bashianshan Mts., Dajiaxi River at Songhe village , 24.17996°N 120.98233°E, 665 m , 5.i.2018, stony river partly with gravel banks: in fine gravel below stones and in green algae mats at the side of the river, Fikáček, Liang & Hsiao lgt. (2018-TW01); 4 spec. ( NMPC): Heping distr., Xueshankengxi River E of Taoshan village, 24.32684°N 120.95377°E, 743 m , 6.i.2018, in gravel and among algae at side of a large stony river, Fikáček, Liang, Hsiao lgt. (2018-TW06). HSINCHU: 2 males, 1 female, ( HCLC): Hengshan Township [DZ山 ė], Youluo Stream [油ǎë], 24.714584°N 121.141335°E, 172m , 14.II.2019. Hsing-Che Liu leg.

Published records. Hualien; Ilan [= Yilan]; Nantou ( Gentili 1989, 1995). Hsinchu; New Taipei ( Gentili 2003).

Diagnosis. Body length 2.0– 2.7 mm, maximum body width 1.4–1.9 mm. Body oval ( Fig. 12 ). head black, with distinct preocular spots (some specimen without pale spots). Pronotum black, with densely punctate and pale margins ( Fig. 20 ). Elytra surface pale, with rows of serial dark spots. Male genitalia ( Fig. 16 ): Aedeagus 0.6 mm long, strongly sclerotized. Median lobe shorter than parameres, widening at midlength, apex subtruncate; parameres weakly narrowing, bent inward in apical third.

Differential diagnosis. Laccobius hammondi very similar to the Japanese L. oscillans , it can be differentiated by the pronotum almost entirely dark and median lobe more dilated at the apical third than L. oscillans .

Distribution. China (Beijing, Fujian, Gansu, Guangdong, Guizhou, Guangxi, Hubei, Hunan, Jiangxi, Liaoning, Sichuan, Shaanxi, Shandong), Taiwan ( Fig. 27 ) ( Gentili 1995; Jia et al. 2013a; Przewoźny 2020, this paper).

Bionomics. Examined specimens were collected at sides of stony streams and rivers ( Fig. 24 ), and rarely also on sun-exposed algal mats together with Hydroscapha takahashii Miwa, 1934 (see photos in Fikáček et al. 2020) or by light trap.

Comments. Preliminary analyses of cox1 sequences of few Taiwanese specimens revealed that Taiwanese specimens identified as L hammondi may in fact represent two distinct species. We observed a slight variation of the aedeagus morphology in our samples, with the median lobe more or less widened, and slightly to apparently shorter than parameres. These observations are based on non-sequenced specimens and we are hence unable to evaluate at the moment whether this variation corresponds to the two molecular lineages or represents an intraspecific variation. A more careful analysis of the situation is needed, based on larger number of specimens sampled across Taiwan, and ideally also including specimens of L. hammondi and related species from China and Japan. We temporarily treat all examined specimens under L. hammondi , despite it may in fact be a complex of species.

Figures

FIGURES 27. Map of Taiwan showing the distribution of the Laccobius species.

FIGURES 10–18. Dosal view of the habitus and male genitalia of Taiwanese Laccobius species (10–13: habitus, 14–18: male genitalia). 10, 14: L. politus Gentili, 1979. 11, 15: L. formosus Gentili, 1979. 12, 16: L. hammondi Gentili, 1984. 13, 17: L. roseiceps Régimbart, 1903. 18: L. fragilis Nakane, 1966, after Nakane (1966).

FIGURES 19–22. Pronotum of Taiwanese Laccobius (Microlaccobius) species. 19: L. formosus Gentili, 1979. 20: L. hammondi Gentili, 1984. 21: L. hoi sp. nov. 22: L. roseiceps Régimbart, 1903.

FIGURES 23–26. Habitat of Taiwanese Laccobius species. 23: Nantou County, Puli: habitat of L. formosus. 24: Taichung City, Wufeng: habitat of L. hammondi and L. hoi sp. nov. 25: Pingtung County, Ligang: habitat of L. formosus, L. hoi sp. nov. and L. roseiceps. 26: New Taipei City, Pingxi: habitat of L. politus.