New data on the little-known species of the water scavenger beetle Helophorus pitcheri Angus, 1970 (Coleoptera: Hydrophiloidea: Helophoridae)

New data on the distribution, ecology, and phenology of Helophorus pitcheri Angus, 1970, previously known from three type specimens from Southern Siberia and a single find from China, are presented. The species is recorded for the first time from the Russian Far East (Amur Region and Khabarovsk Territory). Biotopes are indicated, and a list of Hydrophiloidea species which was found with H. pitcheri is given. Presumably, the species is an acidophilic stagnophile. Adults were found in June and August.


I n t r o d u c t i o n .
The world fauna of the genus Helophorus Fabricius, 1775 contains 189 species. Except for 32 purely Nearctic and about three Afrotropical forms, most of them are distributed in the Palearctic (Angus, Jia, 2019;Smetana, 1985).
The species Helophoris pitcheri Angus, 1970 was described from three specimens from the Lake Baikal region in the collection of E. Reitter. Two males (including the holotype) are labeled 'Transbaikalien', one female is labelled 'Quell. d. Jrbut', -which is obviously an incorrect spelling of the name of the Irkut (Angus, 1995). Another specimen was collected on August 19, 1994 by M. Jäch in the city of Baihe, Changbai-Korea Autonomous County of Jilin Province of China (Angus, l. c.). No further information about this species has been published (Angus, Jia, Chen, 2014). Therefore, H. pitcheri was not included in the 'Key to Insects of the Far East of the USSR' (Shatrovskiy, 1989) -as a species known at that time only from Southern Siberia. It is present in the publication 'Key to Freshwater Invertebrates of Russia and Adjacent Lands' (Kirejtshuk, Shatrovskiy, 2001).
In the collections of the Moscow colleagues Alexander Ryvkin and Elena Veselova from Amur Region and Khabarovsk Territory, the author found nine specimens of this species. The findings are new indications of the distribution, ecology, and phenology of H. pitcheri. M a t e r i a l s a n d m e t h o d s . All studied specimens of H. pitcheri were collected in the Norsky Nature Reserve (Amur Region) and in the Bureinsky Nature Reserve (Khabarovsk Territory) in the summer seasons of 2004 and 2007. The researchers collecting these specimens were oriented on the study of beetles from the family Staphylinidae (mainly the genus Stenus Latreille, 1796). Numerous species from the genus Stenus A. G. SHATROVSKIY New data on the little-known species of the water scavenger beetle Helophorus pitcheri Angus, 1970 (Coleoptera: Hydrophiloidea: Helophoridae)

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inhabit terrestrial coastal biotopes. Therefore, methods of terrestrial collecting were dominated rather than aquatic insects. However, in shallow well-viewed bodies of water, aquatic beetles also trapped whenever possible.
The specimens were mounted in accordance with generally accepted methods. If necessary, beetles were prepared to study the aedeagophore. The material is stored in the collection of the Museum of Nature of the Vasyl Karazin Kharkiv National University.

R e s u l t s a n d d i s c u s s i o n .
H. pitcheri was placed to the section of species with 9-segmented antennae and characteristic pronotum: strongly or moderately convex, without yellow edges, with distinct grooves (Angus, 1970). Currently, R. Angus offers a different approach to the formation of species groups. In particular, he replaced two species from the above section to the frater-praenanus group, named after two defining representatives: H. frater Orchymont, 1926and H. praenanus Łomnicki, 1894(= H. jacutus Poppius, 1907. H. pitcheri was not included in this group (Angus, Jia, Chen, 2014).

H e l o p h o r u s p i t c h e r i Angus, 1970
R e f e r e n c e s . Angus, 1970;Shatrovskiy, 1989;Angus, 1995;Kirejtshuk, Shatrovskiy, 2001;Angus, 2011;Angus, Jia, Chen, 2014;Angus, 2016. Body length: 2.7-3.0 mm. Width: 1.2-1.3 mm. Body elongated irregularly shaped (Fig. 1). Head ( Fig. 3) black, with a greenish reflection and a maroon-bronze tint. Clypeus with longitudinal swelling, trunk and branches of the Y-shaped impression lie in the recess, sometimes of a triangular form depression with reduced grooves along the lateral edges. The surface of the head on the middle part in rare small points passing to the edges in large, and then to rugose points. Large dots carry thin hairs. Stem of Y-shaped impression is narrow, parallel-sided, slightly widened at the site of lateral branch discharge. The maxillary palpi brown; their apical segment asymmetric. Antennae 9-segmented, tawny, club darker.
Pronotum uniformly moderately convex, maximal width in the anterior third, the ratio of width to length 1.6-1.7; the sides to the posterior edges straightened. The main color of the intervals as the head; grooves and marginal grooves -golden-bronze. A surface with a maroon-bronze anterior border, sometimes distributed along the sides, the disc is only with a greenish reflection. Intervals (except the lateral), as well as the median and median grooves, are in rarefied small punctures, passing to the anterior margin and at the lateral intervals into granularity. Puncture points carry thin hairs (Fig. 2). Submarginal and marginal grooves are mainly smooth, can carry small points along the inner edge. Median and submedian grooves narrow, the submarginal and marginal are widened. Internal intervals convex on the base and in the middle part. The middle groove is straight, narrowed to both apices. Submedian grooves curved inward -at the base, outward -in the middle, and straightened to the apex. The submarginal grooves have an expansion in the middle part and a depression in front of the base (Fig. 2). Marginal grooves with an inner uneven edge delimited by grains of external spaces.
Elytra yellowish-brown, with a dark spot in the apical third and on the sides of it -with small dark spots in the 6 th intervals. There are also pale spots forming two oblique bands as a 'herringbone' pattern together with a Λ-mark spot, and apical spot (Fig. 1). Sides convex, widely rounded, tapered to the apex. The ratio of the length to width of the elytra is about 1.6-1.7; their maximal width is beyond the middle. Rows of punctures deepened, intervals convex, twice as wide as the diameter of the punctures. The points in the rows are connected by longitudinal grooves, deepened at the base of the elytra in 2-5 rows. Flanks invisible from the below.

D i a g n o s i s . The species is distinguished by a combination of structures present in the description.
A distinctive characteristic is the structure of the aedeagophore.

F i g . 5 . Distribution of Helophorus pitcheri.
Thus, in the Russian Far East, the species was found in similar biotopes from six points. In the Table 1 are shown the names of the stations in chronological order of the collection points. N o t e s : * -a form with long struts (Angus, 2011(Angus, , 2016; ** -in chronological order.

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The specimen from China (Angus, 1995) was collected in a puddle formed in spring by melting snow (unshaded springfed pools, cold water). In open landscapes, such puddles either dry up at the time of collection (August 19) or become brackish and are the habitat of halophilic species. However, the rainy climate at the collection point helps maintain a neutral reaction of the water, and the indication that the water in the puddles is cold indicates poor evaporation from the surface. Therefore, it is unlikely that the water in the puddles had an alkaline reaction.
From the reports of researchers, it is known that they collected material: in 2004 -from August 2 to October 8, and in 2007 -from May 31 to August 12. However, H. pitcheri adults were collected only in June and August. Based on these data, it can be assumed that the species at the adult stage occurs before the beginning of September. It is possible that in July it stays at the immature stages of development. In June, adults are also collected, but to determine the timing of the start of their release, additional material is required.
C o n c l u s i o n s . 1. New data were obtained on Helophorus pitcheri, previously known for three specimens of the type series from Southern Siberia and a single specimen from the China.
2. The species is mentioned for the first time from the Russian Far East in Amur Region and Khabarovsk Territory.
3. The species is redescribed with details of some morphological characteristics. 4. The habitat requirements of the species are noted. Presumably, it is an acidophilic stagnophile. 5. It has been established that in the Far East, the species at the adult stage occurs in June and August. It is possible that in July the species is at immature stages of development. The start time of the appearance of the imago remains undefined.
A c k n o w l e d g m e n t s . The author is sincerely grateful to his Moscow friends, spouses Alexander Ryvkin and Elena Veselova, who gave to author their material and conditions for its preliminary study. The author is also grateful to his friend Robert Angus (Natural History Museum, London) for valuable remarks on the contents of the article and its text in English.