Laccobius (Microlaccobius) hoi Liu & Fikáček, 2021

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 : 592-594

Laccobius (Microlaccobius) hoi Liu & Fikáček sp. nov. 何氏flǿ牙ḃ

( Figs 1–5 , 21 , 25 )

Type locality. Taiwan, Pingtung County, Ligang Township [¶ffiė], Erchong River [二AEë], 22.7982°N 120.5011°E, 32 m a. s. l.

Type material. Holotype: male ( NMNS): TAIWAN: PINGTUNG: Ligang Township, Erchong River , 22.7982°N 120.5011°E, 32m, 26.IV.2020. Hsing-Che Liu leg. Paratypes: TAIWAN: PINGTUNG: 1 spec. ( HCLC): same data as the holotype . CHIAYI: 1 male, 1 female ( NCHU): Dapu Township [k埔ė], Zengwen Dam [曾Ý水庫], 17.V.2020. Kunta Ho leg. by light trap. KAOHSIUNG: 1 female ( HCLC): Liouguei District [六AE區], Laonong River [Ž濃ë], 24.VI.2020. Hsing-Che Liu & Uitsiann Ong leg. TAICHUNG: 3 spec. ( TARI) Wufeng District [Ȃ峰區], 15.V.2020. Hsing-Che Liu leg.

Description. Form and Color ( Figs. 1–2 ). Body length 2.5–2.7 mm (holotype: 2.6 mm), maximum body width 1.7–1.9 mm (holotype: 1.9 mm). Body oval, moderately convex. Maxillary palpus light brownish yellow, blackish at the very apex of the last palpomere. Antennae yellowish to brown, antennal club slightly darker. Head black, with distinct preocular spots. Labrum and mentum black. Pronotum pale, with irregularly shaped central dark spot ca. as wide as three-fifths of pronotum width ( Fig. 21 ). Elytra pale, with variable pattern of slightly irregular longitudinal series consisting of black spots. Whole scutellar shield black. Ventral surface black with yellowish pubescence. Leg pale yellowish.

Head. Surface densely punctate, sagittal suture indistinct. Eyes moderately large, somewhat protruding, separated by ca. 2.0× the width of one eye. Labrum coarsely punctate, anterior margin not emarginate. Mentum glabrous, ca. 1.2–1.3× as wide as long. Antennae with 8 antennomeres, longer than maxillary palpus, intermediate segments (antennomeres III and IV) very short; each club antennomere of different shape, closely segmented, with long or short pubescence; antennomere VI largest, antennomere VII semicircular in shape, antennomere VIII longer than wide, tapering towards apex.

Thorax. Pronotum ca. 2.6× wider than long; surface rough, loosely punctate. Surface of mesoventrite densely pubescent. Metanepisterna ca. 5.3× as long as wide, parallel-sided; metaventrite densely pubescent except along midline, slightly raised. Scutellar shield in form of equilateral triangle. Elytral surface with slightly irregular rows of serial punctures.

Legs. Profemora densely pubescent basally; protibiae with longest stiff setae situated in apical third. Mesofemora almost bare, with sparse punctation; mesotibiae with longitudinal rows of stiff setae. Metafemora smooth, wider than mesofemora; metatibiae slender, slightly bent inwards.

Abdomen. Ventrites I–V sparsely pubescent; Ventrite VI densely pubescent.

Male genitalia ( Figs. 3–5 ). Aedeagus 0.6 mm long, phallobase slightly narrowed and truncate basally. Median lobe very broad, slightly shorter than parameres, narrowing and membranous at apex, surface with lateral deep rugae. Parameres flattened laterally, very narrow and slightly bent inwards in dorsal and ventral views, strongly narrowing and acute in lateral view.

Differential diagnosis. This species is very similar Laccobius philipinus Gentili, 2005 , but can be distinguished from it by the pronotal dark spot almost as wide as the head (narrower than the head in L. philipinus ; Fig. 6 ), median lobe very wide and almost of the same width throughout except at apex (median lobe moderately wide, indistinctly constricted subapically in L. philipinus ), parameres very narrow, bent inwards, rounded at apex in dorsal and ventral views (parameres moderately wide, straight and pointed at apex in dorsal and ventral views in L. philipinus ). For comparison with the aedeagus of the holotype of L. philipinus , see Figs 7–9 .

Etymology. The species is named after Mr. Kunta Ho who first discovered this species in Pingtung county, Taiwan.

Distribution. This species is known from central and southern Taiwan (Chiayi, Kaohsiung, Pingtung, Taichung; Fig. 27 ).

Bionomics. Specimens from Pingtung and Kaohsiung were collected from a lowland stream and co-occurred syntopically with L. formosus and L. roseiceps ( Fig. 25 ). Specimens from Chiayi were collected in a light trap set near a water reservoir. Specimens from Taichung were collected from a small stream and co-occurred syntopically with L. hammondi ( Fig. 24 ), but L hoi sp. nov. was much less abundant than L. hammondi .

Comments. Gentili (2005) described L. philipinus from the Philippines, but included a single female from Taiwan in the type series. The Taiwanese specimen was collected in Liukui near Kaohsiung. The first author of this study (HCL) visited the area in 2020 and collected the Hydrophilidae from streams and wet rocks in Liukui and surrounding areas in the Kaohsiung county. Three species of Laccobius were found: L. formosus , L. roseiceps and L. hoi sp. nov., but no specimens of L. philipinus . Laccobius philipinus and L. hoi sp. nov. are very similar externally, despite their male genitalia which differ obviously between the species (see differential diagnosis). The paratype of L philipinus from Taiwan designated by Gentili (2005) is deposited in the collection of Elio Gentili in Museo Civico di Storia Naturale, Verona, Italy, and was not examined by us. It seems to correspond to L. hoi sp. nov. by the size of the pronotal dark spot (E. Gentili, pers. comm. July 2020). Therefore, we remove L. philipinus from the Taiwanese fauna.

Figures

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

FIGURES 1–5. Laccobius (Microlaccobius) hoi sp. nov., male. 1–2: habitus of the holotype (1: dorsal, 2: ventral). 3–5: aedeagus (3: dorsal view, holotype, 4: ventral view, holotype, 5: lateral view, paratype). Photos 1–2 by Uitsiann Ong.

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.

FIGURES 6–9. Laccobius (Microlaccobius) philipinus Gentili, 2005. 6: habitus of the holotype, dorsal view. 7–9: aedeagus of the holotype (7: dorsal view, 8: lateral view, 9: ventral view).