﻿Revision of the family Haliplidae (Insecta, Coleoptera) in Japan

﻿Abstract The Japanese members of Haliplidae were reviewed and 13 species in two genera are recognized. A new species, Haliplusmoriisp. nov. is described from Honshu; it is similar to Haliplusjaponicus Sharp, 1873, but belongs to a different subgenus. Haliplusdiruptus J. Balfour-Browne, 1946, syn. nov. is treated as a junior synonym of Halipluskotoshonis Kano & Kamiya, 1931. The records of Haliplusdavidi Vondel, 1991 from Japan are regarded as misidentifications of H.kotoshonis. Haliplusbasinotatuslatiusculus Nakane, 1985, syn. nov. is treated as a junior synonym of H.basinotatus. Haliplusangustifrons Régimbart, 1892 known from south and southeast Asia, is newly recorded from Japan.


Introduction
The Japanese Haliplidae includes 11 species in two genera (Nakajima et al. 2020). Two species of the genus Peltodytes Régimbart, 1879 are recorded (Kamiya 1936) but the genus Haliplus Latreille, 1802 is one of the most diverse of the family. Among the Japanese Haliplus that have been reviewed by Nakane (1963aNakane ( , 1963bNakane ( , 1985 and Satô (1984Satô ( , 1985, there are disagreements in the taxonomic assignments of some species. Since then, van Vondel (1991van Vondel ( , 1995van Vondel ( , 1998van Vondel ( , 2003avan Vondel ( , 2003bvan Vondel ( , 2019 and van Vondel et al. (2006) have extensively examined the Old World species, and the elucidation of Asian species has progressed. However, for Japanese species, unresolved problems remain due to confusion between species whose type specimens may have disappeared (Mori 2007). As a result of re-examination of Japanese Haliplidae, 13 species in two genera, including one new species and one newly recorded species, were found, and are described and illustrated. Additionally, a review was conducted on Japanese Haliplidae, and their distributions, larval stages, and ecological notes have been added.

Materials and methods
Specimens studied herein are deposited at the following institutions and collections:
Dried specimens were observed from the dorsal (HW, CED, PL, PW, EL, EW) and lateral (BT) views, and the maximum length at each measurement site was measured. For observation and measurement, a stereomicroscope (Olympus SZ40, Olympus Corporation, Tokyo, Japan) was used for PL, PW, EL, EW, and BT, and a stereomicroscope (Leica S8 APO) was used for HW and CED.
The terminology of body characters is followed by van Vondel (1991van Vondel ( , 1992van Vondel ( , 2019 and van Vondel et al. (2006). Fig. 1 shows the island names of Japan included in this paper.
Elytra. Yellow to yellow-brown, dark interrupted lines on primary puncture rows, darkened along suture, sometime indistinct marks connecting primary puncture rows. Completely margined. Primary puncture rows moderately strong, dense in first rows, ~ 36 or 37 punctures in first row. Secondary punctures moderately strong and dense along suture, moderately strong and sparse on intervals. All punctures darkened.
Ventral side. Yellow-brown, legs yellow-brown, slightly darkened towards coxae, elytral epipleura yellow-brown with strong punctures, reaching to sixth sternite. Prosternal process narrowed near coxae, grooved along each side, anterior edge weakly margined, moderately strongly punctured. Metasternal process flat or even slightly bulbous with a row of strong punctures on each side, else moderately punctured, emarginate in apical margin (Fig. 8F). Metacoxal plates reaching to fifth sternite, moderately strongly punctured, near suture weakly punctured, row of setae on posterior edge (Fig. 9C, D). Third and fourth sternites not fused with well indicated depression and around ridge. Fifth and sixth sternite with sparse transverse puncture row, last sternite weakly punctured in apical part. No setiferous striole on dorsal face of hind tibia, longer tibial spur of hind legs 2⁄3 length of first tarsal segment (Fig. 8D). Male genitalia. Penis carved in apical and basal part; slender and round in apex (Fig. 10A). Right paramere triangular, apex with long setae and lacking small segment (Fig. 10C).
Similar species. This species may be confused with H. japonicus, but the latter has plicae on the pronotum.
Biology. The type locality is dominated by rice paddy fields in the plains. Distribution. Japan (Tohoku Region). Etymology. The species name is dedicated to Mr. Masato Mori, who first noticed the existence of this species.   Biology. This species typically inhabits stagnant water environments such as ponds, paddies, and swamps, and the adults were collected by sweep netting in shallow water (Nakajima et al. 2020).
Immature stages. Unknown. Distribution. Japan: Hokkaido, Honshu (Tohoku Region), Tsushima; Korea, China, Far East of Russia.    Biology. The above specimens were collected from small ponds. Immature stages. Unknown. Discussion. Haliplus angustifrons is widely distributed from south Asia to southeast Asia (van Vondel 1993; Sheth et al. 2016), but there are no records in east Asia. The pattern of dorsal marks, the shape of the prosternal process, and male genitalia are in agreement with the redescription of H. angustifrons (van Vondel 1993). The figures of "H. kotoshonis" given by van Vondel (1991van Vondel ( , 1993 are not of true H. kotoshonis, and at least the records of Japanese specimens correspond to H. angustifrons. Distribution. Japan (new records): Nansei shoto (Tokuno-shima, Okinawa-jima, Iheya-jima, Kume-jima, Ishigaki-jima, Iriomote-jima); Pakistan, India, Sri Lanka, Nepal, Myanmar, Laos, Vietnam.
Discussion. Nakane (1985) described a subspecies for Japanese population, but we could not find any differences between the Asian (van Vondel 1995: fig. 53) and Japanese populations. In this paper we treat this subspecies as a junior synonym of nominotypical subspecies.

Haliplus (Liaphlus) kotoshonis Kano & Kamiya, 1931
Figs 14, 18F Japanese name: Koto-kogashira-mizumushi Haliplus kotoshonis Kano & Kamiya, 1931: 2. Satô 1985Nakane 1985: 63;1987: 30;Nakajima et al. 2020 Biology. The above specimens were collected from small ponds. Immature stages. Unknown. Discussion. This species was described based on one specimen from "Kotosho" (Orchid Island), Taiwan (Kano and Kamiya 1931). The type specimen is likely to have been lost (Mita et al. 2015), but the black marks on the dorsum are unique and the original description and figures are recognizable. Nakane (1985Nakane ( , 1987Nakane ( , 1990) has repeatedly pointed out that Haliplus diruptus J. Balfour-Browne, 1946 should be a junior synonym of the species, but a formal treatment has not been done. Judging from our investigation of the specimens and the description of van Vondel (1995), H. diruptus is treated as a junior syn- onym of this species in this paper. In addition, Haliplus davidi Vondel, 1991 was recorded from Japan (van Vondel 1998(van Vondel , 2003a, but was later treated as a junior synonym of H. diruptus (van Vondel 2017); therefore, the record of H. davidi from Japan is not H. diruptus but H. kotoshonis.
This study revealed that specimens of Haliplus angustifrons Régimbart, 1892 were mixed in with the specimens identified as "H. kotoshonis" from Japan. In a typical individual, the dorsal marks can easily distinguish between the two species. In particular, this species has a black mark on head, but the H. angustifrons does not have such a mark.

Discussion
In this paper we recognize 13 species belonging to two genera from Japan. Mori (2007) stated that several unrecorded species of the genus Haliplus were known from Nansei shoto and other areas of Japan. These unrecorded species are considered to be H. regimbarti (recorded by Iwata 2016), H. angustifrons (recorded in this paper), and H. morii sp. nov. (described in this paper).