A revisional study of the Chinese species of Amphiops Erichson (Coleoptera, Hydrophilidae, Chaetarthriini)

A review of the genus Amphiops occurring in China is provided. A new species, Amphiops coelopunctatus sp. nov., is described from Hainan, China. Based on a study of the type material, Amphiops yunnanensis Pu, 1963, is proposed as a junior synonym of Amphiops mirabilis Sharp, 1890. Amphiops pedestris Sharp, 1890 and Amphiops annamita Régimbart, 1903 are confirmed as synonyms of Amphiops mater Sharp, 1873. Amphiops coomani d’Orchymont, 1926 is reported from China for the first time. Amphiops globus Erichson, 1843, previously reported from Macau, is found to be a misidentification. An identification key to Chinese species of the genus is provided. http://www.zoobank.org/urn:lsid:zoobank.org:pub:47C95EED-8B09-4BE0-A335-7E8B7CB23FE7


Introduction
Since the genus Amphiops was erected by Erichson (1843), a total of 20 species and four subspecies have been described from the Australian, Oriental and Afrotropical regions (Hansen 1999;Short and Hebauer 2006;Short and Fikáček 2011). Only four species reach the southern boundary of the Palaearctic region: Amphiops senegalensis (Castelnau 1840) and Amphiops phallicus d 'Orchymont, 1936 reach North Africa andIsrael, andAmphiops mater Sharp, 1873 and Amphiops mirabilis Sharp, 1890 reach north of the Yangtze river in China (Beijing and Shandong provinces). d 'Orchymont (1941) and Hebauer (1998) reviewed all species of the Afrotropical region and Watts (1998) reviewed the Australian fauna. Only the Oriental species have not been reviewed.
Here, I provide results of the revisional study on fauna of Chinese Amphiops Erichson.  Taxonomic notes When A.coomani was described by d' Orchymont (1926) based on two type specimens, the measurement given was "3.6 × 2.7millim". This is clearly smaller than the specimens examined by me. The size of these specimens is 3.8-4.2 × 2.7-2.8 mm. I examined a specimen (length 4.0 × 2.75 mm) from Tonkin: Hoa Binh, Hoa Binh, leg. A. de Cooman deposited in SYSU that has the same characteristics as the specimens from China. Unfortunately the specimen from Tonkin is a female and the identification was therefore not confirmed by study of the aedeagus. However, as the type locality of A.coomani Orchymont is not far away from Hoa Binh, I am treating the specimen from Hoa Binh as A.coomani because it has all characters as described by d' Orchymont (1926). There is no doubt that the specimens from China and from Tonkin, Hoa Bihn examined for this study are conspecific. Jäch and Easton (1998) reported A.globus, a very common Afrotropical species, from Macau, China. All specimens I examined from Macau belong to A. coomani which is very similar to A.globus, but clearly differs from it by several characters given above in the diagnosis. Amphiops coomani occurs not only in Vietnam, but also in Indonesia (Java, Sumatra) and South China. Hence, even though I have not had the chance to examine the specimens on which Jäch and Easton's (1998) based their record of A.globus, I consider their record as a misidentification of A.coomani. Amphiops globus is therefore excluded from the Chinese fauna.

Differential diagnosis
This species differs from all other Chinese species by the very distinct frontoclypeal suture, pronotum with distinct wrinkles anteriorly, pronotum with smaller and less apparent systematic punctures than the species of the A.mater complex, elytra with five weak ridges on inner part, clearly striate laterally and apically, and outer five intervals distinctly elevated.

Distribution
China (Fujian). Known only from the type locality.

Diagnosis
Dorsum glabrous, black. Anterior margin of clypeus broadly truncate; head with sparse punctation, all punctures of the same size; lateral portions of pronotum with punctation identical to those on head, punctures on median portion finer; elytra without serial punctures, ground punctation similar to head, lateral punctures somewhat coarser than those on inner parts. Systematic punctures on head, pronotum and elytra of the same size as ground punctures. Lateral margin continuously curved to posterior margin, ( Figure 2F, I), hence posterolateral angle absent. Mesofemora very narrowly separated. Metaventrite without a transverse ridge anteriorly. Mesofemora densely pubescent on basal third, metafemora glabrous, only pubescent along anterior margin on basal half. Aedeagus with median lobe broad, triangular apically, broadly notched behind apex on each side, gonopore situated apically; parameres as long as median lobe, almost parallel-sided, rounded apically, distinctly curved medially on inner face. Abdomen. Covered with hyaline mass. Visible part of first ventrite very short, without median carina, with marginal short and very fine setae anteriorly.

Differential diagnosis
The new species is close to A.coomani and A.globus based on the pronotum without distinct posterolateral corners, elytra without series of coarse punctures, head, pronotum and elytra with ground punctures of single size; metaventrite without a transverse carina anteriorly, and metafemora glabrous with fine punctures. It can be easily distinguished from these species by the dorsum with denser and coarser punctures, pronotum and elytra with systematic punctures of the same size as ground punctures, and median lobe of the aedeagus narrower, triangular apically, broadly notched behind apex on each side.

Etymology
The species name is a combination of Coelostoma, a genus of the hydrophilid tribe Coelostomatini, and the Latin punctatus. The name refers to the fact that the head, pronotum and elytral punctation of this new species are similar to the dorsal punctation of many Coelostoma species.

Biology
Aquatic. Part of type series was collected in an exposed pool connected to the stream and overgrown by grass, while the second part of the series was collected from the gravel on the side of a small streamlet shaded streamlet in the secondary forest c.50 m from the exposed pool (Fikáček and Zhao, pers. comm.).    Sharp, 1890, Amphiops annamita Régimbart, 1903, and Amphiops sumatrensis Régimbart, 1903 as subspecies of A.mater based on the morphology of the aedeagus of the complex and the consideration of "well-defined distinctions on geographical distribution". The specimens in this study show that the ground punctures on the intervals vary in density and size. Some specimens have fewer, sparser ground punctures which are more or less regularly arranged apically, other specimens bear denser and more irregular ground punctures which differ more or less in size apically, and still other specimens have denser ground punctures apically that are irregularly arranged but are more or less similar in size. All of the three forms appear syntopically in the series from Yunnan, Guangxi, Guangdong, Jiangxi and Hunan. The two specimens I checked from Vietnam have the elytra very similar to the typical A. pedestris. Moreover, the aedeagi show that there is no difference among the three forms and there are many specimens with ground punctation intermediate between the above "subspecies". Another subspecies, A.mater pisiformis Fairmaire occurring in Indo-China, may also be conspecific with A.mater Sharp, considering its distribution. d 'Orchymont (1935) and Wu (1936) reported Amphiops annamita Régimbart from Guangdong (Danes Island), A.mater Sharp from Beijing, Fujian (Xiamen), Zhejiang (Hangzhou) and Hubei (Wuchang), and A.pedestris Sharp var. varians Orchymont from Guangdong. These data were used by later entomologists for discussion of the Chinese Amphiops. Gentili et al. (1995) and Hansen (1999) recorded them from China partly based on the Catalogue by d' Orchymont (1935) and Wu (1936). [Although A.annamita Régimbart and A.pedestris Sharp are recognized as subspecies of A.mater currently, Gentili et al. (1995) treated them as valid species without any explanation or justification for the change in rank.] Actually, A.mater Sharp is widely distributed from southern China north to Beijing.  did not know that A.mirabilis also occurs in China. I have been able to check the type in IZCAS. It is clear that A.yunnanensis is conspecific with A.mirabilis.