Research Article |
Corresponding author: Martin Fikácek ( mfikacek@gmail.com ) Academic editor: Pavel Stoev
© 2019 Fenglong Jia, Jia-Hui Chen, Martin Fikácek.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Jia F, Chen J-H, Fikácek M (2019) A new species of Laccobius Erichson, 1837 (Hydrophilidae, Coleoptera) from the Chinese Himalaya, with comments on taxonomic status of subgenera Glyptolaccobius Gentili, 1989 and Cyclolaccobius Gentili, 1991 and additional faunistic records from China. ZooKeys 889: 65-80. https://doi.org/10.3897/zookeys.889.34690
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A new species of the water scavenger beetle, Laccobius (Glyptolaccobius) motuoensis sp. nov., is described from Motuo County, Xizang, China and its diagnostic characters are illustrated. Examination of this new species and re-examination of previously described species revealed that the separation of the subgenus Glyptolaccobius Gentili, 1989 and Cyclolaccobius Gentili, 1991 is artificial: both subgenera are hence combined here. Cyclolaccobius syn. nov. is synonymized with Glyptolaccobius, and the latter is shown to be diagnosed by 7-segmented antennae as a unique synapomorphy. All species treated until now under Cyclolaccobius are here transferred to Glyptolaccobius, with the only exception of L. hingstoni Orchymont, 1926, L. jumlanus Gentili, 2015 and L. zugmayeri Knisch, 1910 which are tentatively transferred to the subgenus Hydroxenus Wollaston, 1867, as their antennae bear eight antennomeres. Three species are recorded for the first time from China: L. (Microlaccobius) orientalis Knisch, 1924 from Xizang, Laccobius (M.) exilis Gentili,1974 from Xinjiang, and Laccobius (M.) sublaevis J. Sahlberg, 1900 from Xinjiang. Additional faunistic data from China are provided for the following species: L. (Microlaccobius) hammondi Gentili, 1984, Laccobius (M.) formosus Gentili, 1979, Laccobius (Hydroxenus) hingstoni d’Orchymont, 1926, Laccobius (Glyptolaccobius) yunnanensis Gentili, 2003, Laccobius (Compsolaccobius) decorus (Gyllenhal, 1827), Laccobius (Dimorpholaccobius) bipunctatus (Fabricius, 1775), Laccobius (D.) striatulus (Fabricius, 1775), Laccobius (s. str.) bedeli Sharp, 1884, L. (s. str.) binotatus d’Orchymont, 1934, Laccobius (s. str.) cinereus Motschulsky, 1860, and Laccobius (s. str.) minutus (Linnaeus, 1758).
Aquatic beetles, new combination, new synonym, Oriental Region, Palearctic Region, water scavenger beetle.
Since the species of the genus Laccobius Erichson, 1837 occurring in China and neighboring areas were reviewed by
In total, 34 species of Laccobius have been recorded from China to date (
A few specimens were dissected for each species examined. After 8–10 hours in 10% KOH at room temperature, male genitalia were transferred to a drop of distilled water, remaining membranes were removed under a compound microscope, and the cleaned genitalia was subsequently mounted into a drop of glycerin on a piece of transparent plastic attached below the respective specimen. Habitus photographs were taken using a Zeiss Discovery V20 with Zeiss AxioCam HRc. Photographs of genitalia were taken using Zeiss Axioskop 40 binocular microscope with a QIMAGING Micropublisher 3.3 RTV camera; the pictures were subsequently combined with the Auto-Montage software. Scanning electron microscope photographs were taken using a Phenom Pro SEM.
Morphological terminology largely follows
Examined specimens are deposited in the following collections:
China, Xizang, Linzhi Prefecture, Motuo County, Lagong, 29°18'50"N, 95°19'07"E.
Holotype
: ♂ (
Length 1.9–2.2 mm. Dorsal surface dark brown or black with broad lateral yellow band on pronotum and elytra, posterior half of elytra yellowish. Head and pronotum without shagreen on interstices. Head without pale preocular spots. Antenna with seven antennomeres, the third antennomere very small, globular. Elytra often with a pair of yellow spots on the base of third primary series of punctures. Elytra without sulci, with 10 primary series of punctures; primary series of punctures strong and coarse, secondary ones consisting of smaller and more scarcely arranged punctures, punctures with short yellow setae. Aedeagus: total length 0.45 mm; median lobe as long as parameres, broad basally, narrowest medially, subapically with a series of backward directed setae; parameres subrectangular apically, almost as wide as medial lobe at apex.
Total length 1.9–2.2 mm (holotype: 2.15 mm); maximum width 1.35–1.45 mm (holotype: 1.4 mm). Total length / total width ratio = 1.5. Body oval, moderately convex, maximum width at anterior third of elytra (Fig.
Head.
Black with greenish reflection, without preocular spots, smooth. Labrum about 2.7× as wide as long, without specula in both sexes, feebly emarginated on anterior margin, surface densely punctured (Fig.
Thorax.
Pronotum transverse, smooth; black with greenish reflection, lateral margins with yellow stripe that extends to posterior margin near posterior corner (Figs
Legs.
Yellow brown. Trochanters pubescent; profemora with anterior surface densely pubescent basally, with tibial grooves; protibiae smooth, bearing stiff setae (Fig.
Abdomen.
Ventrites 1–5 smooth, without microsculpture, sparsely pubescent; each ventrite with long setae posteriorly, ventrite 6 densely pubescent (Fig.
Male.
Second protarsomere dilated, with a clasping structure that contains 7 lobes (Fig.
Aedeagus.
(Figs
This species closely resembles L. yunnanensis Gentili, 2003 and L. sipeki Gentili & Fikáček, 2009 in the genital morphology (including the series of long hairs on distal half of the median lobe) and the coloration of elytra having a dark base with small basal spots and widely pale apical portion. It can be distinguished from L. yunnanensis by having an elytral series regular throughout (somewhat irregular at base in L. yunnanensis), primary series of punctures distinctly stronger and coarser than secondary ones (with some punctures at least as large as those on primary series in L. yunnanensis) and the median lobe ca. the same width in apical half (distinctly widened apically in L. yunnanensis). It can be distinguished from L. sipeki by the absence of the parasutural furrow (with distinct rather deep parasutural groove in L. sipeki) and the apex of the median lobe reaching the level of parameral apices only (slightly overlapping parameral apices in L. sipeki).
This species is named after type locality.
Only known from two close localities in the eastern Himalaya (Xizang, Motuo County).
The subgenera Glyptolaccobius and Cyclolaccobius both contain species that inhabit mostly hygropetric habitats (seepages, wet rocks, sides of waterfalls) and are both characterized by large transverse eyes, which distinguish them from remaining groups of the genus Laccobius. The principal character distinguishing both subgenera is the presence (in Glyptolaccobius) or absence (in Cyclolaccobius) of the ‘parasutural furrow’, i.e., the longitudinal impression situated parallel to the suture in the posterior half of elytra. This character is usually clearly visible in Glyptolaccobius and clearly absent in Cyclolaccobius, but confusion still happens:
Recently,
All these observations motivated us to check the antennal morphology of a wider spectrum of species assigned to Glyptolaccobius and Cyclolaccobius. We examined the following species: L. affinis Knisch, 1927 (the type species of Glyptolaccobius), L. pluvialis Gentili, 2006, L. qinlingensis Jia, Gentili & Fikáček, 2013, L. sipeki Gentili & Fikáček, 2009, L. yinziweii Zhang & Jia, 2017 (all latter with the parasutural furrow, i.e., members of Glyptolaccobius), L. hanka Gentili & Fikáček, 2009, L. hainanensis Jia, Gentili & Fikáček, 2013, L. hingstoni Orchymont, 1926, L. martini Jia, Song & Gentili, 2013, L. nitidus Gentili, 1984, L. politus Gentili, 1979, and L. yunnanensis Gentili, 2003 (all latter without parasutural furrow, i.e., members of Cyclolaccobius). All of these except L. hingstoni have 7-segmented antennae. Moreover, L. hanka (without parasutural furrow, member of Cyclolaccobius) and L. pluvialis (with parasutural furrow, member of Glyptolaccobius) were found as closely related sister taxa in the molecular phylogeny of Toussaint and Short (2018). All this evidence clearly indicates that species assigned at the moment to the subgenera Glyptolaccobius and Cyclolaccobius likely form a monophyletic group characterized by a unique synapomorphy within Laccobius, i.e., the 7-segmented antenna. The presence/absence of the parasutural furrow seems to be a phylogenetically flexible character within Laccobius since species that closely resemble each other in other characters sometimes differ in the presence/absence of the parasutural furrow only. We hence conclude that keeping Glyptolaccobius and Cyclolaccobius as two subgenera is actually more confusing than helpful for taxonomic work, even if these subgenera would be considered just as artificial groups designed to facilitate taxonomic work on this large genus (until a phylogenetic study is performed). For this reason, we are performing the following taxonomic changes here:
1. We synonymize Glyptolaccobius Gentili, 1989 with Cyclolaccobius Gentili, 1991 syn. nov.
2. Glyptolaccobius sensu nov. is diagnosed by having antennae with seven antennomeres (in contrast to eight antennomeres in remaining subgenera of Laccobius). All species currently treated under Cyclolaccobius and having 7-segmented antennae are here transferred to Glyptolaccobius.
3. The only three species treated until now as Cyclolaccobius which do not have 7-segmented antennae (i.e., L. hingstoni, L. zugmayeri Knisch, 1910 and L. yumlanus Gentili, 2015; see
Additional studies are necessary to understand the systematics of Laccobius and to test the phylogenetic position of L. zugmayeri and related species as well as to test the monophyly of the subgenera. At the moment, only the subgenus Glyptolaccobius in the new meaning (i.e., containing all Laccobius species with 7-segmented antenna, and characterized by a hygropetric lifestyle) and Yateberosus (a New Caledonia endemic subgenus with the larva having closed spiracular system and abdomen bearing tracheal gills, see
Male genitalia of the species similar to Laccobius motuoensis sp. nov. 17–19 L. sipeki Gentili & Fikáček, holotype (17 ventral 18 lateral 19 ventral) 20–22 L. yunnanensis Gentili, specimen from China: Yunnan: Rehai Hot springs (coll.
1 | Elytra with distinct parasutural furrows | 2 |
– | Elytra without distinct parasutural furrows | 3 |
2 | Body length 2.7–2.9 mm; elytra without pale yellow spots at base; median lobe bearing lateral subapical rows of stout spines (Jia et al, 2013: figs 3–5) | L. qinlingensis Jia, Gentili & Fikáček |
– | Body length 1.8–2.1 mm; base of elytra with two or four distinct pale yellow spots; median lobe without lateral subapical rows of spines ( |
L. yinziweii Zhang & Jia |
3 | Body length 2.0–2.8 mm; elytral borders and epipleura are swollen at base; median lobe narrowly pointed apically ( |
L. nitidus Gentili |
– | Body length 1.8–2.1 mm; elytral borders and epipleura are not swollen at base; median lobe rounded apically | 4 |
4 | Apical part of the median lobe without series of fine setae. Elytra completely black at the base. Species from Hainan and Taiwan | 5 |
– | Apical part of the median lobe with series of fine setae. Elytra with or without pale basal spots. Continental species | 6 |
5 | Median lobe strongly constricted subapically (Jia et al. 2013: figs10–12). Hainan | L. hainanensis Jia, Gentili & Fikáček |
– | Median lobe indistinctly constricted subapically (Jia et al. 2013: figs 14–16). Taiwan | L. politus Gentili |
6 | Elytral series regular throughout; primary series of punctures distinctly stronger and coarser than secondary ones; median lobe ca. of the same width in apical half (Figs |
L. motuoensis sp. nov. |
– | Elytral series somewhat irregular at base, with some secondary punctures at least as large as those on primary series; median lobe distinctly widened apically (Figs |
L. yunnanensis Gentili |
XIZANG: 41 spec. (
Body length 2.8–3.0 mm. Frons between eyes ca. 2.6–3.0× as wide as one eye in dorsal view. Pronotum black or dark brown medially, with a pair of light spots at anterior margin, with broad yellow band laterally, without shagreen, smooth and shining. Punctures of third and fifth elytral rows uniform, arranged almost in a straight line (a few punctures slightly out of line). Aedeagus (Fig.
Widely distributed species, recorded from north Africa through Near East and Central Asia to the Himalaya and Tibetan Plateau (
XINJIANG: 15 spec. (
Body length 2.3–2.7 mm. Frons between eyes ca. 2.8–3.0× as wide as one eye in dorsal view. Pronotum black or dark brown medially, without a pair of light spots at anterior margin, with broad yellow band laterally, without shagreen, smooth and shining. Punctures of third and fifth elytral rows uniform, arranged almost in a straight line (
Widely distributed species, recorded from Turkey through Central Asia to the Himalaya, Myanmar and the Tibetan Plateau (
XINJIANG: 1 male (
Size 2.8–3.0 mm. Frons between eyes ca. 2.8–3.0× as wide as one eye. Pronotum black or dark brown medially, without a pair of light spots at anterior margin, with broad yellow band laterally, without shagreen, smooth and shining. Punctures of third and fifth elytral rows in disorder, not arranged in straight lines (
Central Asian species reaching to the Tibetan Plateau and the Himalaya Region (
SICHUAN: 3 spec. (
See
SICHUAN: 3 spec. (
See
XIZANG: 11 spec. (
See
YUNNAN: 5 spec. (
China (Yunnan: Lushui, Mojiang), Myanmar.
QINGHAI: 1 male (
See
XINJIANG: 9 spec. (
See
XINJIANG: 6 exs. (
See
XINJIANG: 1 male (
See
QINGHAI: 12 spec. (
See
QINGHAI: 19 spec. (
See
XINJIANG: 23 spec. (
See
We thank Mr Zu-Long Liang, Sun Yat-sen University, for his help to prepare SEM photographs. We are grateful to Mr Zhou Run from the Chinese Academy of Sciences, Institute of Zoology, Beijing, China, for his donation of some specimens. This work was financially supported by National Natural Science Foundation of China (31772494) to F.-L. Jia and J.-H. Chen, and by the Ministry of Culture of the Czech Republic (DKRVO 2019-2023/5.I.a, National Museum, 00023272) to M. Fikáček.