Corresponding authors: Fenglong Jia (
Academic editor: Pavel Stoev
The Chinese species of the genera
Jia F, Lin R, Li B, Fikáček M (2015) A review of the omicrine genera Omicrogiton, Mircogioton and Peratogonus of China (Coleoptera, Hydrophilidae, Sphaeridiinae). ZooKeys 511: 99–116. doi:
A total of 15 genera and 104 species of the tribe
Since 2009, a lot of material of the tribe
Male genitalia were dissected in a portion of specimens of each species. In specimens deposited in SYSU, dissected genitalia was transferred to a drop of absolute alcohol for removing membranes after 8-10 hours in 10% KOH at room temperature, and subsequently mounted into a drop of glycerine on a piece of transparent plastic slide attached below the respective specimens. In specimens deposited in NMPC and in the holotype of
Detailed descriptions of the tribe
Examined specimens are deposited in the following collections:
For comparative reasons, we have examined also the following material of
The following key allows to identify all genera of the tribe
1 | Antenna with 8 antennomeres, antennal club loosely segmented. Mesoventral plate slightly wider than long, subpentagonal, contacting metaventral process |
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(more species known from China, to be revised by the authors) | ||
– | Antenna with 9 antennomeres, antennal club compact. Mesoventral plate either wider than long, longer than wide, or distinctly isolated from metaventrite |
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2 | First ventrite not carinate medially. Mesoventral plate narrowly elongate |
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– | First ventrite carinate medially. Mesoventral plate broadly pentagonal |
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3 | Mesoventral plate fused with metaventral process, forming a common meso-metaventral keel. First metatarsomere much longer than second metatarsomere (best seen in dorsal view) |
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(one species known from China: |
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– | Mesoventral plate not contacting metaventrite, separated from the latter by a broad gap. First metatarsomere only a little longer than second metatarsomere (best seen in dorsal view) |
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a | Pronotum with fine mesh-like microsculpture on interstices (best seen with spot light and using the light diffuser). Adeagus as in Figs |
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– | Pronotum without microsculpture on interstices. Parameres with or without S-shaped sclerite |
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b | Aedeagus elongate. Phallobase very short. Paramere without S-shaped strongly sclerotized part, narrow and nearly straight. Median lobe very wide apically, with very large gonopore (Fig. |
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– | Aedeagus robust and wide. Phallobase only slightly shorter than parameres. Parameres with strongly sclerotized S-shaped sclerite. Median lobe narrow apically, with small subapical gonopore (Fig. |
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4 | Mesocoxae widely separated; mesoventral plate much wider than long, widely contacting metaventrite. Prothorax with antennal grooves |
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– | Mesocoxae rather narrowly separated; mesoventral plate in form a narrowly carinate elevation, only narrowly contacting mesoventrite. Prothorax without antennal grooves |
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(two species from Taiwan available in our material) | ||
5 | Size 2.0–2.2 mm, highly convex beetles. Elytral series deeply impressed especially sublaterally. Epipleuron wide anteriorly, then becoming extremely narrow, seemingly absent in posterior third of elytra. Pronotum with a transverse series of slightly coarser punctures along posterior margin |
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(single species occurring in China, |
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– | Size 1.2–1.7 mm, at most moderately convex beetles. Elytral series not distinctly impressed. Epipleuron gradually narrowing posteriad, well developed in the posterior third of elytra. Pronotum without distinct transverse row of slightly larger punctures along posterior margin |
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(multiple species occur in China, a taxonomic revision is needed) |
Lectotype (hereby designated): dissected male (BMNH): “LACTHO / Tonkin. / de Cooman // Andrewes / Bequest / B. M. 1922-22 //
General habitus of Chinese
Body length 1.9–2.1 mm, width 1.2–1.3 mm. Head and elytra brown; scapus ca. 3.5× as long as antennomeres 2–5 combined. Interstices of pronotum with fine mesh-like microsculpture; prosternum strongly tectiform. Phallobase ca. half as long as parameres, without distinct manubrium; paramere without strongly sclerotized S-shaped portion, rather wide throughout, weakly sinuate on outer margin, apex semicircular; median lobe slightly narrower than paramere, wide basally, then abruptly narrowing and rather narrow in apical half, apex narrowly rounded, gonopore small, apical.
When
Within this study, we are showing that
All examined specimens were found in the decaying banana trunks, typically in still standing trunk bases which are decaying after the apical part of the plant was cut or broken.
China (Guangdong, Hong Kong), northern Vietnam. New for China.
Holotype: male (SYSU): CHINA: Hainan Isl.: Limushan Mts., 19°9.1–9.2'N, 109°45-46'N, along the road, 550–750 m a.s.l., rotting banana trunks at the stream in secondary forest, 5.v.2011, Fikáček & Zhao lgt. Paratypes: 2 males (SYSU, NMPC): same locality as the holotype; 2 males (NMPC): China: Hainan Isl.: Jianfengling Mts., Tiachi Lake env., Bishu villa, rotting banana trunk at the bank of a drying-up stream in the primary forest above the hotel area,
Body length 1.9–2.0 mm. Head and elytra brown; scapus ca. 3.5× as long as antennomeres 2–5 combined. Interstices of pronotum without microsculpture; prosternum weakly tectiform. Phallobase ca. as long as parameres, wide anteriorly, with wide rounded manubrium; paramere with strongly sclerotized S-shaped portion and membranous mesal and apical portions, sclerotized parts of left and right paramere forming very obtuse angle basally; median lobe narrower than phallobase and paramere, rather wide basally, gradually narrowing towards apex, apex rather widely rounded, gonopore subapical (Fig.
The species name is patronymic, referring to the Hainan Island where this species is commonly collected.
All type specimens were collected in decaying banana trunks in primary or secondary rainforests. On the type locality, the specimens of this species were collected in the same banana trunk as two other
China (Hainan).
Holotype: male (SYSU): CHINA: Hainan isl., Limushan Mts., Limu temple, 5.v.2011, 19°9.1–9.2'N, 109°45–46'E, 550–750 m; along the road, rotting banana trunks at the stream in secondary forest, Fikáček & Zhao lgt.
Body length 2.1 mm. Head and elytra black or dark brown; pronotum paler than head and elytra. Scapus ca. 2.5× as long as antennomeres 2–5 combined. Prosternum strongly tectiform, with low longitudinal carina medially. Phallobase much shorter than parameres, with thin and long basal manubrium; paramere without distinct S-shaped more sclerotized portion, narrow, weakly curved on outer margin, rounded apically; median lobe much broader than paramere, bottle-shaped, widest at basal third, strongly narrowing ca. at midlength, apex broadly truncate; gonopore large, situated subapically (Fig.
The species is named after Dr. Robert Bagrie Angus, a British specialist on the
The holotype was collected in a decaying banana trunk together with specimens of
China (Hainan).
Body length 3.2–3.4 mm, width 2.2 mm. Dorsal surface dark brown, ventral surface brown to dark brown. Labrum weakly bisinuate on anterior margin, not distinctlx projecting anteriad. Scapus ca. 2.2× as long as antennomeres 2–5 combined, slightly shorter than antennal club. Head, pronotum and elytra with similar sparse and fine punctation, interstices without fine microsculpture; elytra with 10 series of punctures, series 6–7 abbreviated anteriorly. Prosternum strongly tectiform, sharp anteriorly. Mesoventral elevation much longer than wide, with distinct longitudinal groove medially, posteriorly fused with metaventral process, not projecting posteriad into a process overlapping metaventrite. Metaventrite with a longitudinal glabrous elevated band medially, forming together with mesoventral plate a joint meso-metaventral elevation. Phallobase ca. 0.3× as long as paramere; paramere rather wide throughout, outer margin slightly concave subapically, apex semicircular. Median lobe slightly narrower than paramere, lateral margin almost parallel, apex narrowly rounded, gonopore of moderate size, subapical (Fig.
This species was described by
The recently collected specimens examined here were found in decaying banana trunk (K.-Q. Song and L. Tang, pers. comm.).
China (Yunnan), northern Laos. New genus and species for China.
Syntypes: 2 specimens on one card (BMNH): “
Morphology of
Body length 2.1 mm, width 1.5 mm, strongly convex. Head and pronotum with fine microsculpture between punctures. Elytra with 10 striae, striae 1–5 reaching elytral base, striae 6–10 abbreviated anteriorly, not reaching base; elytral intervals with distinct fine punctures, without microsculpture between punctures. Prosternum steeply raised in middle to form a triangular medially carinate tablet. Mesoventrite flat medially, widely fused with metaventrite. Metaventrite laterally with much coarser and stronger punctures than on its median portion. Aedeagus (Figs
Ventral morphology (14) and morphology of aedeagus (15–22).
This species can be easily distinguished from
This species was firstly described from Nagasaki, Kyushu in southern Japan by
When
Most specimens examined here were found by sifting forest leaf litter.
China (Guangdong, Jiangxi, Taiwan), Japan (Honshu, Kyushu). New genus and species for mailand China.
Examples of habitats of Chinese
We are indebted to Dr. Robert B Angus who checked and dissected types of