Enochrus (Holcophilydrus) umbratus, stat.rev.
Creators: name: Ryndevich, Sergey K.
name: Prokin, Alexander A.
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Hydrophilidae
Enochrus
Enochrus umbratus

description: Enochrus (Holcophilydrus) umbratus (Sharp, 1884) stat.rev.
Figs 11–14, 17–18, 25–26, 42–44, 48, 52, 53.
Philydrus umbratus Sharp, 1884: 454 (partim).
MATERIAL. Type material. Lectotype (present designation). Male, Japan, “ Philydrus umbratus, Types D.S., [Lake] Chiuzenji [Nikko, Tochigi Prefecture], Japan, 24.8.1881, Lewis” [Sharp’s writing on the face of the card], “Type” [printed label], “ Japan, G. Lewis” [printed label], “Sharp Coll. 1905- 313” [printed label], ” Lectotypus, Philydrus umbratus Sharp, 1884 ♂, des. Shödl, 1996” [red label Shödl 's writing], Lectotype ” [blue bordered round printed label]; “ Philydrus umbratus Sharp, lectotype, S. Ryndevich & A. Prokin des., 2021” [white printed label]. Paralectotypes. Japan: 2 females [originally mounted on one card with lectotype], same data as for lectotype, but “ Paralectotypus, Philydrus umbratus Sharp, 1884 ♀, des. Shödl, 1996” [2 red label Shödl 's writing], “ Paralectotype ” [blue bordered round printed label]; “ Philydrus umbratus Sharp, paralectotype, S. Ryndevich & A. Prokin des., 2021 [2 red printed labels]”; male and female [originally mounted on one card] “ Philydrus umbratus, Chiuzenji, 24.8.81, Japan, Lewis“[Sharp’s writing], “ Japan, G. Lewis” [printed label], “Sharp Coll. 1905-313” [printed label], ” Paralectotypus, Philydrus umbratus Sharp, 1884 ♂ (& ♀), des. Shödl, 1996” [2 red labels Shödl 's writing], “ Paralectotype ” [blue bordered round printed label]; “ Philydrus umbratus Sharp, paralectotype, S. Ryndevich & A. Prokin des., 2021 [2 red printed labels] (all in NHML).
REMARKS. Type material has labels by Stefan Schödl (1957–2005), but the lectotype of the species had never been officially designated until now.
The species was described from Nikko, Niigata, Yokohama and Hakodate, but we haven't studied the type material from Yokohama. Lectotype is placed on one card (left) with two paralectotypes (females). Male genitalia of males mounted on a plastic plates and placed below the card on a pin.
Paralectotypes of Philydrus umbratus) from Hakodate and Niigata (Figs 28, 45–46) are belongs to Enochrus simulans.
REDESCRIPTION. Form and colour. Body oval, slightly convex (Figs 11–14), length 5.4–6.1 mm, width 2.9–3.3 mm. Maximum body width in basal part, in front of middle of elytra. Lateral margins of the elytra is smoothly rounded at the apices (Figs 13–14). Dorsal side reddish-yellow to yellowish-brown. Basal part of the head and central triangular spot are black. Central dark spot reaches the labrum and occupies most part of head. Triangular spot of the female is larger than that of male. Labrum of male and female dark (Figs 17–18). Lateral parts of labrum of male slightly paler. Pronotum with four small and one large central dark spots (Figs 11–12). Lateral parts of pronotum and elytra paler. Punctate rows not darkened (Figs 11–12). Maxillary palpomeres and antennae yellowish to reddish-yellow or brownish- yellow except for darker club. The last segment is darkened on apex. Ventral surface black to dark brown, posterior margins of abdominal ventrites paler, brown or reddish-brown. Legs reddish-yellow. Posterior margins of femora darker, tarsi brownish-yellow or reddish-yellow.
Head. Dorsal surface with dense evenly punctation with moderately coarse punctures being of equal size, without microsculpture. Groups of larger and coarser punctures are located around the inner edge of eyes and along anterior margin of head. Clypeus with dense, moderately coarse punctures, interstices without microsculpture. Anterior margin of clypeus with very narrow bead. Eyes big, hardly protruding, emarginated anteriorly, separated by ca. 4.2–4.3× width of one eye (Figs 17–18). Mentum almost flat with setae in anterior part, 1.6 times as wide as long. Antennae with 9 antennomeres, scapus about 1× as long as antennomeres 2–5 combined, club non compact. Maxillary palpomere 4 symmetrical with, ca. 1.4× as long as, palpomere 3 in length.
Thorax. Elytra and pronotum without microsculpture, have very rare large punctures (with rare trichobothria). Pronotum 3.2–3.4 times as long as elytra. Pronotum ca. 2.0–2.1× as wide as long, strongly narrowed anteriorly. Pronotal punctation similar to that on head. In lateral part of pronotum large punctures forming oval which interrupted from inside at the center level of pronotum. Margins of pronotum narrowly rimmed. Prosternum well developed, protruding anteromedially, with a transverse groove, carina, which can only be detectable posteriorly. Mesoventral elevation high acute and dentiform (Fig. 48). Metaventrite not abruply raised, with dense punctate pubescence median pentagonal area ca. 0.9–1 × as long as wide, center of pentagonal area glabrous. Scutellum expanded, ca. <1 × as long as wide. Elytra with 9 punctate striae, barely noticeable punctate row at outer edge of elytra. Punctate striae near elytral base smoothed out and poorly distinguishable. Short scutellary stria in base of first elytral interval absent. Large punctures (with trichobothria) in elytra situated in the 3 rd, 5 th, 7 th and 9 th elytral intervals. Humeral bulge not distinct. Epipleura rather weakly oblique anteriorly, more so posteriorly. Femora with sparse and shallow punctures ventrally, pubescence part of metafemora occuped about 1/7 of femoral length. Tarsi with very short pale setae ventrally. Fifth tarsomere about as long as tarsomeres 3–4 combined. Claw not long, not wide spaced from fifth protarsomere of male (Fig. 44).
Abdomen. Abdomen with five exposed ventrites, dense uniformpubescence; first ventrite not carinate; ca. as long as second ventrite, fifth ventrite arcuate, not emarginate apically.
Male genitalia (Figs 52–53). Phallobase symmetrical, about 1.2 times as long as paramere. Parameres strong narrow in apical half; rounded at apex, noticeably joined at apex (Fig. 53). Penis with narrowly spaced ароdemes, apical part about 1.4 times as long as ароdemes, corona large, situated subapically.
PUBLISHED RECORDS. Japan [Zaitsev, 1908; Hansen, 1999, 2004].
DISTRIBUTION. Japan: Honshu (Fig. 60).
NOTE. All records of E. umbratus from mainland Eurasia (Russian Far East, South Korea), the Kuril Islands and most localities from Japanese islands (with the exception of Honshu) refer to E. simulans [Kamiya, 1940, Lee et al., 1992, Lee, 1994, Kim et al., 1994, Hansen, 1999, 2004, Kirejtshuk, Shatrovskiy 2001, Cho, Park, 2010, Ryndevich, 2014].
BIONOMICS. Water beetles. Type specimens were collected in lake.
description: Published as part of Ryndevich, Sergey K. & Prokin, Alexander A., 2024, Taxonomic status of Enochrus simulans and E. umbratus (Coleoptera: Hydrophilidae), pp. 430-444 in Russian Entomological Journal 33 (4) on pages 441-442, DOI: 10.15298/rusentj.33.4.04, http://zenodo.org/record/14722312