Alpagut masakazui, Yamada & Hayashi, 2020

Yamada, Kazutaka & Hayashi, Masami, 2020, First East Asian record of the genus Alpagut (Hemiptera: Heteroptera: Dipsocoridae), with description of a new species and a note on the metacoxal adhesive pad of Dipsocoridae, Zootaxa 4768 (2), pp. 271-281 : 273-277

Alpagut masakazui sp. nov.

( Figs. 1–20 , 23–24 )

Cryptostemma sp. B: HIURA (1967): 80.

Type material. Holotype: ♂ ( Figs. 1–3 ), ‘ JAPAN: Tokushima- / ken, Sanagouchi-son , / Shimo, 34°00′45″N / 134°28′45″E, 36 m / 18 V 2018, K. Yamada’ [printed]; mounted on triangle card, in intact condition ( TKPM) . Paratypes: JAPAN: HONSHU: Ishikawa Pref.: 1 ♂, Nakanoto-machi, Kue-harayamabun, 1.x.2015, K. Watanabe ( TKPM). Shimane Pref.: 6 ♂♂ (one in Figs. 7–15 , 18 ) 3 ♀♀, Izumo-shi , Inome-cho , Inomegawa Riv., 35.440804, 132.710732, 4.vii.2015, M. Hayashi ( TKPM, MNHN); 1 ♂ 1 ♀, Unnan-shi, Kisuki-cho, Nishihinobori, Hiikawa Riv., 35.248616, 132.897052, 2.xi.2006, M. Hayashi ( TKPM); 9 ♂♂ 9 ♀♀ (one in Figs. 4–6 , one in Figs. 16–17 , one in Figs. 23–24 ), same locality, 1.viii.2015, M. Hayashi ( TKPM, HOWP, NMPC). SHIKOKU: Tokushima Pref.: 1 ♀, same locality as holotype, 34.012500, 134.479167, 6.xi.2017, K. Yamada ( TKPM); 1 ♂, same locality as holotype, 34.012500, 134.479167, 26.iv.2018, K. Yamada ( TKPM); 2 ♂♂, same data as holotype, 34.012500, 134.479167 ( TKPM); 1 ♂ 2 ♀♀, Kaifu, Kawakami, Kangase, 24.x.1962, I. Hiura ( OMNH). KYUSHU: Fukuoka Pref.: 2 ♂♂ 2 ♀ ♀, Magaribuchi, 10.iii.1957, K. Morimoto ( ELKU); 1 ♀, same locality, 5.iv.1957, K. Morimoto ( ELKU); 1 ♂ 1 ♀, Kanetake, Muromigawa Riv., 14.iv.1957, S. & M. Miyamoto ( ELKU). Nagasaki Pref.: 1 ♀, Nagasaki-shi, Iwaya shrine, 4.viii.2017, T. Yasunaga ( TKPM) .

Differential diagnosis. Readily distinguished from all other known congeneric species by the larger body (2.0– 2.68 mm) ( Figs. 1–6 ), male mediotergite 3 without finger-like appendages ( Fig. 7 ), male left laterotergite 3 (lt3) greatly fused with the sternite and distinctly produced posteriorly ( Figs. 8–9 ), enlarged male left laterotergite 6 (lt6) with a plate-shaped oblong appendage ( Figs. 7, 9–10 ), apical process of left paramere broad and strongly curved posteriorly, with hook-shaped tip ( Fig. 13 ), and female abdomen superficially symmetrical in dorsal view ( Fig. 16 ).

Description. Male. Body oblong-oval, large (2.0– 2.68 mm).

Coloration ( Figs. 1–6 , 19 ). Head light brown to chestnut-brown; eyes and ocelli dark red; antennae yellowishbrown; labium yellowish-brown. Pronotum light brown to chestnut-brown; posterior margin with a wide dark band; anterior margin sometimes with a narrow dark band. Scutellum light brown, paler along the scutellar margin. Forewing somewhat darker than the pronotum. Ventral surface of thorax uniformly smoky brown. Abdomen dark brown.

Surface and vestiture. Head impunctate, sparsely covered with short setae; clypeus, bucculae, and labrum with dense semi-erect setae ( Figs. 1–6 ), with 5–6 pairs of very long erect setae on each side of clypeus, inner side of an- tennal insertion, and near front margin of each eye; apex of clypeus with single long erect seta; eyes with scattered short setae.Antennal segment 1 with sparse setae at apex; segment 2 covered with short semi-erect setae, intermixed with long erect setae, of which the longest seta is longer than the width of the segment ( Figs. 1–6 ); segments 3 and 4 sparsely covered with mix of short and long setae, of which the longest seta is longer than three times the width of corresponding segment ( Figs. 1–6 ). Labium sparsely covered with a mix of short and long setae. Pronotum im- punctate, with sparse short setae, and with a pair of relatively long setae near posterolateral angles. Legs densely covered with short setae. Forewings with short setae on veins. Abdomen densely covered with long reclining setae; left laterotergite 6 and left side of sternite 7 (st7) lateral with long setae ( Figs. 2 , 7–9 ); left side of mediotergite 7 (mt7) bearing distinct setae ( Fig. 7 ); left laterotergite 7 (lt7) basal with long stout setae ( Figs. 9, 11 ); left laterotergite 8 (lt8) densely covered with distinctively long setae on basal portion ( Figs. 7–9, 12 ); left paramere with 4–6 long setae on apical process and with long stout setae intermixed with short setae on basal process, basal process with row of very short setae on basal portion of outer margin ( Figs. 13–14 ); right paramere with several long setae on anterior lobe and with a row of very short setae on outermost margin ( Fig. 15 ).

Structure. Head: triangular, produced anteriorly with rounded apex ( Figs. 1–6 ); head width across eyes ap- proximately 1.5 times wider than interocular distance; eyes small, granulate; ocellus touches the median margin of the respective eye. Antennal segment 1 stout, slightly longer than its diameter; segment 2 slightly narrower than the width of the segment 1, approximately 2.4 times as long as segment 1; segment 3 much longer than segment 4. Labium reaching to the anterior part of mesosternum; segment 1 wider than other segments, slightly longer than width; segment 3 approximately 1.3 times longer than segment 2; segment 4 approximately as long as segment 2. Thorax: pronotum trapezoidal in dorsal view ( Figs. 1, 4 ), approximately 0.45 of its basal width in length; anterior margin slightly curved; lateral margin weakly carinate; posterior margin slightly concave; pronotal collar sulcus de- veloped only laterally; posterior disc flattened, with a transverse row of minute punctures. Legs: fore femora slightly thicker than mid and hind femora; fore tibiae thickening toward apex, apically with dense, slender spines on ventral surface; mid femora apically with a few long spines; mid tibiae slightly expanded at apex, bearing several spines on apicoventral and outer surfaces, with spine shorter than maximum width of mid tibia; hind coxae with small adhesive pad on medial surface; hind femora with two long spines on dorsal surface, one on middle part and the other on apical part; hind tibiae distinctly longer than fore and mid tibiae, bearing 4 longer spines on dorsal surface and 4 apical spines on ventral surface, of which the longer spine shorter than maximum width of hind tibia; tarsal formula 3-3-3. Forewing: surpassing apex of abdomen; marginal vein loop cut by costal fracture; venation as shown in Fig. 14 . Pregenital abdomen: all segments strongly asymmetrical, sinistrally curved ( Fig. 7 ); right laterotergites 2 (lt2)–6 clearly divided into dorsal and ventral laterotergites (7 not clearly divided into two sclerites) ( Figs. 7–9 ); mediotergite 3 very large, without finger-like appendages ( Fig. 7 ); mediotergite 4–6 narrowed sinistrally ( Fig. 7 ); mediotergite 7 elongate, strongly sinuate on left side ( Fig. 7 ); pair of dorsal abdominal gland scars (dag) present near anterior margin of mediotergites 4–6 ( Fig. 7 ); left laterotergites present on segments 4 and 5 (not divided into dorsal and ventral laterotergites) ( Figs. 8–9 ); left laterotergites 2, 3 and 6 greatly fused with the respective sternites ( Figs. 7–9 ); left laterotergite 3 distinctly produced posteriorly, apex somewhat elevated dorsally ( Figs. 7, 9 ); left latero- tergite 6 enlarged in lateral view, with a plate-shaped oblong appendage ( Figs. 7, 9–10 : lt6ap); left laterotergite 7 weakly L-shaped ( Fig. 11 ); sternite 3 with produced posteriorly on right side ( Fig. 8 ); sternite 7 expanded on right side, posterior margin strongly concave ( Fig. 8 ); spiracles located on laterotergites 3–7 (on left side, located on laterotergite 4–6 and sternite 7), and subbasally on left laterotergite 8 ( Figs. 8–9 ). Genitalia: mediotergite 8 (mt8) asymmetrical, wide on right side, strongly curved and narrowed on left side ( Figs. 7, 12 ); two appendages of me- diotergite 8 present on right and middle parts of posterior margin, slender with small projection as base, roughly equal in size each other ( Figs. 7, 12 : mt8ap); left laterotergite 8 weakly twisted, apically bifurcated into two pro- cesses, extremely swollen at base ( Figs. 9, 12 ); pygophore (py) large and roughly turbinate, approximately twice of sternite 8 (st8) on length ( Figs. 7–9 ), anterodorsally with ridges and process (anterodorsal projection); left paramere (lp) stout, subequal in length to right paramere, basal process (bpp) with two large lobes (swollen and triangular lobes),, apical process (app) broad and strongly curved posteriad with hook-shape tip ( Figs. 7, 9, 13–14 ); right paramere (rp) flattened, basal process with two lobes, apical process large and rounded ( Figs. 7, 15 ).

Female ( Figs. 16–17 ). Similar to male in coloration, surface, and vestiture; tarsal formula 2-2-3; forewing usually surpassing apex of abdomen; abdomen superficially symmetrical in dorsal view; tergites 7 (t7) and 8 (t8) symmetrical, with cuticular thickenings (ct) on right and left sides of anterior and posterior margins and along lateral margin ( Fig. 16 ); left side of anterior margin of tergites 7 and 8 slightly thickened than right side from anterior view. Genitalia: spermatheca as shown in Figs. 16–17 ; loculus capsulae present; seminal capsule (sc) situated in the left side of the cavity, gently surrounded by two lamellar expansions; lamellar expansion 1 ( Fig. 16 : le1) derived from left side of posterior part of tergite 7; lamellar expansion 2 ( Fig. 16 : le2) from left side of anterior part of sternite 7, a little narrower than le1; the expansions weakly curved, not closely covering the seminal capsule; lamellar expansion also present on right side of anterior margin of sternite 7; seminal capsule spherical, large, (diameter approximately 0.1 mm), turns into a caudal appendage on one side and forms a short canal leading to intermediate piece (ip) of the spermathecal duct (d) ( Fig. 17 ); intermediate piece extremely swollen as a large vesicular dilation on anterior part ( Fig. 17 ); spermathecal gland (g) fused near a caudal appendage of seminal capsule, slender, bulbous at apex ( Fig. 17 ).

Measurements. Males (n = 10, holotype in parentheses). Body length 2.00–2.68 (2.35); head width across eyes 0.42–0.47; interocular distance 0.27–0.31; length of antennal segments I – 0.08–0.09 (0.09), II – 0.18–0.22 (0.19), III – 0.51–0.55 (0.55), and IV – 0.39–0.48 (0.42); length of labial segments II – 0.10–0.14 (0.13), III – 0.14–0.17 (0.17), and IV – 0.11–0.14 (0.14); length of pronotum along meson 0.28–0.34 (0.31); width of pronotum 0.59–0.79 (0.66); length of forewing 1.55–2.10 (1.80); length of hind tibiae 0.61–0.80 (0.68).

Females (n = 10). Body length 1.93–2.40; head width across eyes 0.42–0.47; interocular distance 0.27–0.31; length of antennal segments I – 0.08–0.10, II – 0.16–0.20, III – 0.43–0.53, and IV – 0.33–0.41; length of labial seg- ments II – 0.09–0.14, III – 0.15–0.18, and IV – 0.11–0.13; length of pronotum along meson 0.28–0.32; width of pronotum 0.58–0.78; length of forewing 1.45–1.90; length of hind tibiae 0.61–0.75.

Etymology. It was named after Dr. Masakazu Hayashi who collected valuable specimens herein designated as type series and provided useful biological information and explicit photographs of this new species.

Distribution. Japan (Honshu, Shikoku, Kyushu).

Bionomics. Most specimens of this species were collected under stones along the bank of the river in the low mountain area ( Figs. 21–22 ) and sometimes found together with Cryptostemma miyamotoi Yamada & Hayashi, 2019 and Pachycoleus japonicus (Miyamoto, 1964) ( Yamada & Hayashi 2019) . In the Hiigawa River, Shimane Prefecture, some individuals were also found from wet moss on stones in the channel of the river ( Fig. 22 ). In the laboratory observation, one individual of this species entered the water along moss on the stone (Masakazu Hayashi pers. comm.). Fine air bubbles enveloped on its body surface in the water ( Fig. 20 ). This evidence suggests the possible existence of a plastron for respiration in this species. As indicated by Štys (1990), when individuals are submerged, a plastron film that may combine with a large air bubble develops immediately over their bodies.

Figures

FIGURES 1‒6. Habitus of Alpagut masakazui sp. nov. 1–3, Holotype, male, dorsal (1), lateral (2), and ventral (3) views; 4–6, paratype, female, dorsal (4), lateral (5), and ventral (6) views. Scale bars = 0.5 mm.

FIGURES 7‒15. Morphological details of Alpagut masakazui sp. nov., male. 7–9, Abdomen, dorsal (7), ventral (8), and lat- eral (9) views; 10, left laterotergite 6 with an appendage, laterodorsal view; 11, left laterotergite 7, laterodorsal view; 12, tergite 8, dorsal view; 13–14, left paramere, two different aspects; 15, right paramere, dorsal view.Abbreviations: dag = dorsal abdomi- nal gland scars; app = apical process of paramere; bpp = basal process of paramere; lp = left paramere; lt2–8 = laterotergite 2 to 8; lt6ap = appendage of laterotergite 6; mt7–8 = mediotergite 7 to 8; mt8ap = appendage of mediotergite 8; py = pygophore; rp = right paramere; st7–8 = sternum 7 to 8. Scale bars = 0.2 mm for 7–9; 0.1 mm for 10–15.

FIGURES 16‒18. Morphological details of Alpagut masakazui sp. nov. 16, Female genital segments, dorsal view; 17, sper- matheca; 18, right forewing of male, dorsal view. Abbreviations: cf = costal fracture; clf = claval fracture; ct = cuticular thick- ening; d = spermathecal duct; g = spermathecal gland; ip = intermediate piece; le1 and le2 = lamellar expansion 1 and 2; sc = seminal capsule; t7–8 = tergite 7 to 8. Scale bars = 0.5 mm for 18; 0.1 mm for 16–17.

FIGURES 19‒22. Living individuals and habitats of Alpagut masakazui sp. nov. 19, Specimen from Inomegawa Riv., Izumo-shi, Shimane Pref. (sex unidentified); 20, specimen from Hiikawa Riv., Unnan-shi, Shimane Pref., in the water (sex unidentified); 21–22, habitat, Hiikawa Riv., Unnan-shi, Shimane Pref. The arrow shows the collecting site (the wet moss on the stone in the channel of the river)—all photographs by Masakazu Hayashi, published with permission.

FIGURES 23‒28. Scanning electron micrographs of metacoxal adhesive pad of Dipsocoridae members. 23–24, Alpagut masakazui sp. nov., paratype, female; 25–26, Cryptostemma pavelstysi, male; 27–28, Pachycoleus japonicus, female. Arrows show metacoxcal adhesive pad.