﻿Three new species of Oocyclus Sharp, 1882, with additional records from China (Coleoptera, Hydrophilidae, Laccobiini)

﻿Abstract Three new species of the water scavenger beetle genus Oocyclus Sharp, 1882 from China (Oocyclusextensussp. nov., from Xizang, O.latiorificialissp. nov. and O.ximaensissp. nov. from Yunnan) are described and illustrated in detail. Additional faunistic data, illustrations of habitus and male genitalia, and a key to Chinese species are provided.


Introduction
Oocyclus Sharp, 1882 is a pantropical genus of water scavenger beetle that is highly adapted to waterfalls and seepages.All known species are restricted to rock-face seeps, margins of waterfalls, and various kinds of vertical surfaces with water (Hebauer and Wang 1998;Short andGarcia 2010, Short et al. 2013;Short and Perkins 2004;Short and Swanson 2005;Toussaint and Short 2018).Currently, a total of 81 species have been described, of which 20 are known from the Oriental Region and 61 from the Neotropical Region (Minoshima 2009;Short 2009;Toussaint and Short 2018;Jordão et al. 2018;Santana et al. 2023;Alencar et al. 2022).Only six species have been recorded in China so far, of which O. bhutanicus Satô, 1976, cited from Taiwan by Hebauer and Wang (1998), needs to be confirmed (Short and Swanson 2005).Previous reports of Oocyclus in China have been limited to the southeastern part of the country (Hebauer and Wang 1998;Short and Jia 2011;Jia and Mate 2012).The distribution of the genus in other parts of China is still unknown.
Recently, we had the opportunity to visit some nature reserves in Yunnan and Xizang and discovered several Oocyclus species, of which three are described here as new to science.We also studied the Oocyclus collections at the Biological Museum, Sun Yat-sen University, and added information about the distribution of Chinese species.

Materials and methods
Some of the specimens were dissected.Dissected male genitalia were transferred to a drop of distilled water, remaining membranes were removed under a compound microscope, and the cleaned genitalia were then mounted in a drop of soluble resin on a paper card attached below the respective specimen.For photography, the cleaned and relaxed male genitalia were placed in a drop of glycerin.Photographs of genitalia were taken using a Zeiss AxioCam HRc camera mounted on a Zeiss AX10 microscope with the Axio Vision SE64 software.These images were then stacked in Helicon Focus v. 7.0.2.Habitus photographs were taken using a Nikon DS-Ri2 mounted on a Nikon SMZ25; layers were captured and stacked in the NIS-Elements software.Habitat images were taken using Canon 7D digital camera.The generic characters are described in detail by Hansen (1991) and Short and Perkins (2004).Morphological terminology largely follows Hansen (1991) and Short and Perkins (2004).For a diagnosis of Oocyclus the reader is referred to Clarkson and Short (2012).
Examined specimens are deposited in the following collections:

IZCAS
Chinese Academy of Sciences, Institute of Zoology, Beijing, China SYSU Sun Yat-sen University, Guangzhou, China Diagnosis.Body large, length 5.3-6.2mm, oblong-oval, and moderately convex.Dorsum black, with greenish luster under lateral illumination, slightly iridescent.Head, pronotum, and elytra with dense ground punctures consisting of extremely fine and moderately coarse punctures.Systematic punctures on labrum sparse and fine, not forming a continuous transverse row or groove.Posterolateral corners of pronotum angulate.Elytral suture slightly raised posteriorly; with 5 distinct rows of regular systematic punctures; lateral margins of elytra distinctly expanded outwards.Pseudepipleura wide from base to apex.Procoxae with sparse, spine-like setae scattered in fine pubescence.Meso-and metafemora without microsculpture on intervals of punctures.Abdominal ventrites with uniform pubescence over entire surface.Aedeagus (Fig. 1D) with parameres almost as long as median lobe; gradually narrowed from apical fourth to apex; apex of paramere slightly curved inwards and rounded.Median lobe slightly narrowed apically, gonopore situated apically, anterior margin of gonopore rounded.

Descriptions of new species
Description.Form and color (Fig. 1A-C).Length 5.3-6.2mm, width 3.4-4.0mm; oblong-oval and moderately convex; elytra longer than wide.Dorsum black, with greenish luster under lateral illumination, slightly iridescent, more vividly colored when alive.Maxillary and labial palps yellowish brown, with last

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maxillary palpomere apically darkened.Antennae yellowish brown, with cupule (sixth antennomere) dark reddish brown or dark brown; club black.Ventral surface black.Epipleura, lateral margins of prosternum, and tarsomeres reddish brown; femora, tibiae, and sternites black or blackish brown.Head.Labrum, clypeus, and frons with both extremely fine and moderately coarse ground punctures; distance between punctures 0.2-3.0×width of 1 puncture.Systematic punctures on labrum sparse, not forming a continuous transverse row or groove, each systematic puncture with a long seta.Systematic punctures on clypeus almost undetectable.
Frons with an irregular row of systematic punctures mesad of each eye, slightly larger than largest ground punctures and usually bearing long setae.Clypeus with a few very indistinct systematic punctures along anterolateral margins, slightly larger than surrounding ground punctures, and bearing short setae.Antennae with scape as long as antennomeres 2-5 combined, first 2 antennomeres of club subequal in length, and apical antennomeres slightly shorter than preceding 2 antennomeres combined.Maxillary palps short, subequal in length to the width of labrum, palpomere 2 slightly dilated, apical palpomeres ca 1.3× as long as penultimate.Labial palps ca 3/4× as the width of mentum.Mentum quadrate, anterior margin slightly convex; with coarse punctures on anterior and lateral portion, only with few punctures posteromedially.Thorax.Ground punctation on pronotum and elytra composed of extremely fine and moderately coarse punctures evenly mixed and distributed.Pronotal systematic punctures present, ca 1.5× the size of ground punctation and set with a fine seta, sometimes partially blending with coarser ground punctures; anterior and posterior series each forming an irregular row.Lateral margins of pronotum set with a few sparsely distributed setiferous punctures.Pronotum with anterior and lateral marginal rims, posterior marginal rim absent.Posterolateral corners of pronotum angulate.Prosternum moderately tectiform, with median carina along entire length, with a small blunt tooth anteriorly.Elytra with 5 distinct rows of punctures, diameter of systematic punctures ca 2× as wide as the coarse ground punctures; lateral margin of elytra distinctly expanded outwards, especially in posterior half; elytral suture slightly raised but easily detectable.Pseudepipleura wide throughout.Mesoventral process with lateral extensions sloping evenly downward.Metaventrite with an oval glabrous area posteromedially, slightly longer than wide, length of glabrous area as long as the total length of metaventrite.Pro-and mesocoxae densely pubescent; procoxae with sparse spine-like setae.Ventral surface of profemora densely pubescent at basal fifth, remainder scattered with fine punctures, interstices without microsculpture; meso-and metafemora glabrous, with coarse punctures and without microsculpture.Protibiae with several spines on dorsal face.Fifth tarsomere of pro-and mesotarsus subequal in length to the preceding 4 tarsomeres combined.Fifth metatarsomere equal in length to second tarsomere.Abdomen.Abdominal ventrites 1-5 with uniform pubescence, longest setae about as long as the setae around the metaventral glabrous area.Fifth ventrite entire.Aedeagus (Fig. 1D).Phallobase with basal 2/3 arcuate, manubrium gradually narrowed at posterior 1/3 and rounded posteriorly.Parameres almost as long as phallobase, widest at the base, arcuate medially outwards, gradually narrowed from apical fourth to apex; apex of paramere slightly curved inwards and rounded.Median lobe slightly narrowed apically, gonopore triangular, apically situated, and with rounded anterior margin.
Remarks.This species is similar to Oocyclus rupicola Minoshima, 2009 from Laos.It can be distinguished from O. rupicola by its on average larger body size (length 5.3-6.2mm, width 3.4-4.0mm vs length 4.93-5.85mm, width 3.03-3.53 in O. rupicola), sparse, fine systematic punctures on labrum which do not form a continuous transverse row (vs forming a row of coarse punctures in O. rupicola), and rounded apex of the paramere of the aedeagus (vs narrowed and obliquely truncate inwards in O. rupicola) (Minoshima 2009).
Etymology.This species is named extensus, Latin, meaning "stretched out" and referring to the outwardly expanded elytra.
Biology. (Fig. 4A-D) The examined specimens were collected on exposed, seeping rock surfaces on the valley edge.They were together with other species of the family Hydrophilidae: Oocyclus bhutanicus Satô, 1979, Agraphydrus nepalensis Komarek, 2018, Laccobius regalis Knisch, 1924, and Coelostoma gentilii Jia, Aston & Fikáček, 2014.Adults hide in rock crevices during the day and are active at night.
Distribution.(Fig. 9) China (Xizang).Only known from type locality.Zhêntang Town is in a valley on the southern side of the central Himalayas and is a border town on the China-Nepal border and lies on the Pum Qu River.Diagnosis.Body medium-sized, length 4.1-4.3mm, oval, and rather convex.Dorsum black, with distinct greenish luster under lateral illumination, slightly iridescent.Head, pronotum, and elytra with dense ground punctures consisting of extremely fine and moderately coarse punctures.Systematic punctures on labrum moderately dense, forming a nearly continuous transverse row.Posterolateral corners of pronotum evenly rounded.Elytral suture not raised; without distinct rows of systematic punctures; lateral margins of elytra not expanded outwards.Pseudepipleura narrowed posteriorly.Procoxae without distinct, spine-like setae in fine pubescence.Meso-and metafemora with fine microsculpture on intervals of punctures.Abdominal ventrites with uniform pubescence over entire surface.Aedeagus (Fig. 2D) with parameres almost as long as median lobe; inner margin of paramere sinuate in dorsal view and distinctly, subapically curved inward; apex of paramere broadly rounded.Median lobe parallel-sided medially, slightly widened at site of gonopore; gonopore situated apically; anterior margin of gonopore pointed.

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lateral margins of prosternum, and posterior margin of each ventrite light brown to dark reddish brown, with remainder of venter darker reddish brown.Head.Labrum, clypeus, and frons with both extremely fine and moderately coarse ground punctures, distance between punctures 0.5-4.0×as the width of 1 puncture.Systematic punctures on labrum moderately dense, forming a nearly continuous transverse row, with moderately long setae.Frons with an irregular row of systematic punctures mesad of each eye, bearing fine erect setae.Clypeus with a few very indistinct systematic punctures along anterolateral margins, slightly larger than surrounding ground punctures and bearing short setae.Antennae with scape subequal in length to antennomeres 2-5 combined; first two antennomeres of club subequal in length, and apical antennomere slightly longer than two preceding antennomeres combined.Maxillary palps short, subequal in length to the width of labrum; palpomere 2 slightly dilated, apical palpomere ca 1.3 as long as penultimate.Labial palpi ca 3/4 width of mentum.Mentum quadrate, anterior margin slightly convex, bearing very fine and scattered punctures.
Thorax.Ground punctation on pronotum and elytra composed of extremely fine and moderately coarse punctures evenly mixed and distributed.Pronotal systematic punctures present, ca 1.5-2.0×size of ground punctation and set with a fine seta, sometimes partially blending with coarser ground punctures; anterior and posterior series each forming an irregular row.Lateral margins of pronotum set with a few sparsely distributed setiferous punctures.Pronotum with anterior and lateral marginal rims, posterior marginal rim absent.Posterolateral corners of pronotum evenly rounded.Prosternum moderately tectiform, with median carina along entire length but without distinct anteromedial tooth.Elytra without distinct rows of larger punctures, systematic punctures almost as coarse as coarser ground punctures, distinguished by the presence of fine, short setae; lateral margins of elytra not expanded outwards; elytra suture not raised.Pseudepipleura narrowed posteriorly.Mesoventral process with lateral extensions sloping evenly downward.Metaventrite posteromedially with an oval glabrous area, slightly longer than wide, length of glabrous area about 2/3 of the total length of metaventrite.Pro-and mesocoxae densely pubescent, without distinct spine-like setae.Ventral surface of profemora densely pubescent at basal 1/5, remainder scattered with fine punctures, interstices with fine microsculpture; meso-and metafemora glabrous, with coarse punctures and fine microsculpture.Protibiae with several spines on dorsal face.Fifth tarsomere of pro-and mesotarsus subequal in length to the preceding 4 tarsomeres combined.Fifth metatarsomere equal in length to second tarsomere.Abdomen.Abdominal ventrites 1-5 with uniform pubescence, longest setae about as long as the setae around the metaventral glabrous area.Fifth ventrite entire.Aedeagus (Fig. 2D).Phallobase parallel-sided to slightly arcuate at basal half, manubrium gradually narrowed at posterior 1/2 of phallobase and rounded posteriorly.Parameres slightly longer than phallobase, widest at the base and gradually narrowed, inner margin of paramere sinuate in dorsal view and distinctly curved subapically; apices broadly rounded.Median lobe almost as long as parameres, parallel-sided medially, and slightly widened at site of gonopore; gonopore triangular, situated apically, and with pointed anterior margin.
Remarks.This species is very similar to O. bhutanicus Satô, 1979, but can be easily distinguished by meso-and metafemora with fine microsculpture on intervals of punctures (vs lacking microsculpture in O. bhutanicus), aedeagus with median lobe as long as parameres and almost parallel-sided medially, slightly widened at level of gonopore (vs median lobe shorter than parameres and gradually narrowed from base to apex in O. bhutanicus), anterior margin of gonopore pointed (vs rounded in O. bhutanicus), and inner margin of paramere sinuate in dorsal view and distinctly curved subapically (vs inner margin of paramere almost straight in dorsal view in O. bhutanicus).This species also shares diagnostic features with O. ximaensis sp.nov., but it can be distinguished from the latter by dorsum with distinct greenish luster under lateral illumination (vs greenish luster weaker in O. ximaensis), meso-and metafemora with fine microsculpture (lacking microsculpture in O. ximaensis), and aedeagus with median lobe almost parallel-sided medially, slightly widened at level of gonopore (vs median lobe gradually narrowed from base to apex in O. ximaensis).
Etymology.Species name is combination of Latin latus, "wide", and orificialis, "orifice", referring to the widely open gonopore.
Biology.This species was founding living on wet rock surface at the margins of a waterfall.
Distribution.(Fig. 9) China (Yunnan).Only known from type locality.Diagnosis.Body medium-sized, length 3.8-4.4mm, oval, and rather convex.Dorsum black, with weak greenish luster, slightly iridescent.Head, pronotum, and elytra with dense ground punctures consisting of extremely fine, moderately coarse punctures.Systematic punctures on labrum moderately dense, forming a nearly continuous transverse row.Posterolateral corners of pronotum evenly rounded.Elytra suture not raised, without distinct rows of systematic punctures; lateral margins of elytra not expanded outwards.Pseudepipleura narrowed posteriorly.Procoxae without distinct, spine-like setae in fine pubescence.Meso-and metafemora without microsculpture on intervals of punctures.Abdominal ventrites with uniform pubescence over entire surface.Aedeagus (Fig. 3D) with parameres almost as long as median lobe; inner margin of paramere slightly sinuate in dorsal view and hardly curved subapically; apex of paramere rounded.Median lobe gradually narrowed from base to apex; gonopore situated apically; anterior margin of gonopore pointed.

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to yellowish brown, with remainder of venter darker yellowish brown.Head.Labrum, clypeus, and frons with both extremely fine and moderately coarse ground punctures, distance between punctures 1.0-3.5×width of 1 puncture.Systematic punctures on labrum moderately dense, forming a nearly continuous transverse row setting with moderately long setae.Frons with an irregular row of systematic punctures mesad of each eye, bearing fine, erect setae.Clypeus with a few very indistinct systematic punctures along anterolateral margins, slightly larger than surrounding ground punctures, and bearing short setae.Antennae with scape subequal in length to antennomeres 2-5 combined, first 2 antennomeres of club subequal in length, and apical antennomere slightly longer than 2 preceding antennomeres combined.Maxillary palps short, subequal in length to the width of labrum, palpomere 2 slightly dilated, apical palpomeres ca 1.3 as long as penultimate.Labial palps ca 3/4 width of mentum.Mentum quadrate, anterior margin slightly convex, bearing very fine and scattered punctures.Thorax.Ground punctation on pronotum and elytra composed of extremely fine and moderately coarse punctures evenly mixed and distributed.Pronotal systematic punctures present, ca 1.5-2.0×size of ground punctation and set with a fine seta, sometimes partially blending with coarser ground punctures; anterior and posterior series each forming an irregular row.Lateral margins of pronotum set with a few sparsely distributed setiferous punctures.Pronotum with anterior and lateral marginal rims, posterior marginal rim absent.Posterolateral corners of pronotum evenly rounded.Prosternum moderately tectiform, with median carina along entire length but without distinct anteromedial tooth.Elytra without distinct rows of larger punctures, systematic punctures almost as coarse as coarser ground punctures, distinguished by the presence of fine and short setae; lateral margins of elytra not expanded outwards; elytra suture not raised.Pseudepipleura narrowed posteriorly.Mesoventral process with lateral extensions sloping evenly downward.Metaventrite posteromedially with an oval, glabrous area, slightly longer than wide, length of glabrous area ca 2/3 of total length of metaventrite.Pro-and mesocoxae densely pubescent; without distinct spine-like setae.Ventral surface of profemora densely pubescent at basal 1/5, remainder scattered with fine punctures, interstices smooth, without microsculpture; meso-and metafemora glabrous, with coarse punctures and without microsculpture.Protibiae with several spines on dorsal face.Fifth tarsomere of pro-and mesotarsus subequal in length to the preceding 4 tarsomeres combined.Fifth metatarsomere equal in length to second tarsomere.Abdomen.Abdominal ventrites 1-5 with uniform pubescence; longest setae about as long as setae around metaventral glabrous area.Fifth ventrite entire.Aedeagus (Fig. 3D).Phallobase slightly arcuate at basal 2/3; manubrium gradually narrowed at posterior 1/3 and rounded posteriorly.Parameres slightly longer than phallobase, widest at the base and gradually narrowed; inner margin of paramere slightly sinuate in dorsal view and hardly subapically curved; apex rounded.Median lobe almost as long as parameres, gradually narrowed from base to apex; gonopore triangular, apically situated; anterior margin of gonopore pointed.
Remarks.This species is very similar to O. bhutanicus Satô, 1979, but it can be distinguished from the latter by dorsum with weak greenish luster under lateral illumination (vs distinct greenish luster in O. bhutanicus), aedeagus with median lobe as long as parameres (vs shorter than parameres in O. bhutanicus), anterior margin of gonopore pointed (rounded in O. bhutanicus).Etymology.This species is named after Xima Town, where the type locality is located.
Biology. (Fig. 5A-C) This species was found on the surface of vertical stone walls with seepage on the side of the river valley.
Distribution.(Fig. 9) China (Yunnan).Only known from type locality.Distribution.(Fig. 9) China (Guangdong, Guangxi).Newly recorded from Guangxi.Distribution.(Fig. 9) China (Hainan), Indonesia, Malaysia, Thailand (Short and Swanson 2005).Body length over 5.3 mm (Fig. 7A).Head, pronotum, and elytra with extremely fine and moderately coarse ground punctures.Lateral margins of elytra distinctly expanded (Fig. 6A).(Clarkson and Short 2012).In South Asia and Southeast Asia, as well as southern China, many species remain undescribed.A distribution map of the genus in China is presented in Fig. 9.Some provinces in central and western-central China, such as Anhui, Hubei, Chongqing, and Sichuan, receive abundant rainfall and have a suitable climate.Therefore, it is very likely that some unknown species having pattern-2 elytral punctures occur in these regions.

A key to Chinese species
Although Oocyclus species are similar in shape, some Neotropical and Oriental groups have evolved some special characters.All 24 Brazilian Oocyclus possess pale spots (or "taillights") on the posterior quarter of the elytra (Clarkson and Short 2012; Jordão et al. 2018;Alencar et al. 2022), apart from the recently described O. paraiso from the Guiana Shield, which lacks these spots (Santana et al. 2023).This color feature is found in only two other species of the genus from Venezuela (Clarkson and Short 2012).None of the Oriental species have such a character.Ground punctures in most of the Oriental species vary in size, but only a few Neotropical species have such similar characters.These differences are probably the result of geographical isolation and microenvironment.
The distributions of most species show strong geographic patterns.The pattern of distributions of Venezuelan Oocyclus strongly corresponds to mountain ranges and rock outcrops (Short and Garcia 2010).In the fauna of the Neotropical and Oriental regions, only a few species are widely distributed, suggesting that species of Oocyclus species may be predominantly local endemics.In China Oocyclus species are known to co-occur with species of other genera of Hydrophilidae (Enochrus, Coelostoma, Laccobius), Hydraenidae (Limnebius), and Torridincolidae (Satonius) (Hájek et al. 2011).Species of these genera, which also inhabit wet rocks or margins of waterfalls, have been collected from Zhejiang Province, Hubei Province, and the Qingling Mountains.The areas in China north of the Yangtze River receive less rainfall and have fewer long-term waterfalls or wet-rock habitats.As a result, no species of Enochrus, Coelostoma, Laccobius, Limnebius, or Satonius, which inhabit wet rocks or the margins of waterfalls, have been collected there to date.

Figure 1 .
Figure 1.Oocyclus extensus sp.nov.A dorsal view B lateral view C ventral view D dorsal view of aedeagus.Scale bars: 1 mm.

Figure 2 .
Figure 2. Oocyclus latiorificialis sp.nov.A dorsal view B lateral view C ventral view D dorsal view of aedeagus.Scale bars: 0.5 mm.

Figure 3 .
Figure 3. Oocyclus ximaensis sp.nov.A dorsal view B lateral view C ventral view D dorsal view of aedeagus.Scale bars: 0.5 mm.

Figure 4 .
Figure 4. Habitats of Oocyclus extensus sp.nov.A valley at Zhêntang Town (Xizang), roadside with waterfalls B wet rock with fine flowing water C, D adults at night.

Figure 5 .
Figure 5. Habitat of Oocyclus ximaensis sp.nov.A river valley with forests on both sides in Xima Town (Yunnan); the red arrow indicates the rock wall with flowing water B, C adults at night.