Elatophilus nipponensis Hiura, 1966

Yamada, Kazutaka & Yasunaga, Tomohide, 2021, The tribe Anthocorini in Japan (Hemiptera: Anthocoridae): descriptions of new species, review of distribution and bionomics, Acta Entomologica Musei Nationalis Pragae 61 (2), pp. 375-426 : 383-384

Elatophilus nipponensis Hiura, 1966

( Figs 1E–F , 2C , 3I–L , 18 )

Elatophilus nipponensis Hiura, 1966: 29 . Holotype: J, Japan, Nagano Pref., Sugadaira (OMNH).

Elatophilus nipponensis : Fඈඋൽ (1979): 58 (listed, distribution); ZHൺඇG & Lංඇ (1985): 192 (habitat, redescription, distribution); Mංඒൺආඈඍඈ & YൺඌඎඇൺGൺ (1989): 165 (listed, distribution); ZHൾඇG & Bඎ (1990): 25 (listed); Pඣඋංർൺඋඍ (1996): 117 (catalogue, distribution); Sඈඇඈൻൾ (1997): 54 (record, as Anthocoris chibi ); TൺKൾඇඈ (1998): 44 (listed); Fൺൻඋൾ et al. (2000): 791 (bionomics); Hඎൺ (2000): 198 (listed, distribution, habitat); Bඎ & ZHൾඇG (2001): 164–165 (figures, in key, redescription); YൺඌඎඇൺGൺ (2001b): pl. 94, 282 (photo, diagnosis, habitat); SHංආඈඇඈඒൺ (2001): 68, 74 (record, photo); MൺൾHൺඋൺ (2009): 65 (record, habitat, photo);AඌൺHං et al. (2010):68 (record, bionomics); MൺൾHൺඋൺ (2011): 123 (record, habitat); MൺൾHൺඋൺ (2012):35 (record, distribution, habitat, bionomics); Kඈඇඇඈ (2012a): 54 (record, photo, habitat); Hൺඈ & Mൺ (2013): 36 (listed); NඈඓൺKං & NඈඓൺKං (2013): 33 (record); Kඈඇඇඈ (2014): 4 (record, habitat); Yൺආൺൽൺ (2015): 381 (distribution, habitat); MൺൾHൺඋൺ (2015): 29 (record, distribution, habitat); Yൺආൺൽൺ et al. (2016): 422 (catalogue, distribution); YൺඓൺKං (2016): 81–82 (listed, photo); Sൺඐൺൽൺ (2018): D-36 (listed); Mൺൾ- Hൺඋൺ (2018): 679 (photo, diagnosis, distribution, habitat); Kඈඇඇඈ (2020): 18 (record, habitat).

Type material examined. Pൺඋൺඍඒඉൾ: ♀, ‘[Kyûshû] \ Sanguzan \

(Chikuzen) \ 10. v. 1931 \ K. Yasumatsu’ [printed], ‘ Elatophilus [handwritten] \ nipponensis ♀ [handwritten] \ n.sp. [handwritten] \ Det.I. Hiura,

1966 [printed]’, ‘ PARATYPE \ ♀ ’ [handwritten] ( ELKU).

Additional material examined. JAPAN: HඈඇඌHඎ: Yamagata Pref.: 1

J ( Figs 3I–K ),Yamagata-shi, Kamisakurada, Kamisakurada forest road,

8.xii.2009 (nymph collected), H. Konno. Tochigi Pref.: 1 J ( Figs 1E–F ),

Mashiko-cho, Takatateyama, 14.iv.2010, S. Maehara; 1 ♀ ( Figs 2C , 3L ),

Sano-shi, Toyoshiro, 26.iv.2008, S. Maehara (all in TKPM).

Differential diagnosis. Recognized by the following combination of characters: body ( Figs 1E–F ) generally blackish brown; head much longer than width across eyes; vertex approximately 2.5 times as width of eye in dorsal view in male, approximately three times as width of eye in female; labium extending to procoxae; lateral margin of pronotum ( Fig. 1E ) straight or very slightly curved, slightly explanate on anterior half; pronotal callus weakly swollen, posteriorly demarcated by transverse depression; posterior lobe behind callus transversely rugose; hemelytra ( Fig. 1E ) with whitish marking on clavus, membrane smoky dark brown with basal portion whitish; pro- and mesotibiae tinged with yellowish brown. Most similar in general appearance to E. matsucocciphagus Bu & Zheng, 2001 , but distinguished from that species by the lateral margin of pronotum being slightly explanate on the anterior half (in E. matsucocciphagus , lateral margin entirely explanate) and the hemelytra with whitish marking on clavus (in E. matsucocciphagus , median part of clavus, and inner 1/3 to 1/2 of endocorium grayish white). In addition, the paramere of this species is slender and longer than that of E. matsucocciphagus .

Redescription. Male genitalia ( Figs 3I–K ): Pygophore ( Fig. 3I ) covered with 6–7 long, stout setae intermixed with short, suberect setae along outer margin and on posteroventral surface, of which the longest setae are approximately half the length of the pygophore; paramere ( Figs 3J–K ) curved, basally twisted, with a few very short, erect setae on middle portion; pronounced groove present, formed by weakly rolled anterior and posterior edge; apical portion of anterior edge weakly dentate.

Female genitalia ( Fig. 3L ): Copulatory tube fused on middle of intersegmental membrane between sterna VII and VIII; basal 1/3 of copulatory tube extremely expanded and bulbous with rugosities and then gradually narrowed apically; apical 2/3 much thinner than basal 1/3 portion with many twists; sperm pouch broken off during the dissection; trunk of conductive tissue not pronounced (or possibly dissolved).

Measurements [mm; JJ (n = 2) / ♀♀ (n = 2)]. Body length 4.00–4.25 / 4.13–4.25; head length (excl. neck) 0.55–0.57 / 0.57–0.58; head width across eyes 0.51–0.52 / 0.47; vertex width 0.24–0.27 / 0.28–0.29; length of antennal segments I – 0.22 / 0.23–0.24, II – 0.78–0.80 / 0.75–0.83, III – 0.38–0.39 / 0.40–0.42, and IV – 0.40 / 0.41–0.42; length of labial segments II – 0.28–0.30 / 0.32–0.33, III – 0.55 / 0.60–0.65, and IV – 0.30–0.31 / 0.36; anterior pronotal width 0.38–0.39 / 0.39–0.43; mesal pronotal length 0.40 / 0.42–0.45; basal pronotal width 1.05–1.13 / 1.12–1.15; length of embolial margin 1.30–1.35 / 1.27–1.37; length of cuneal margin 0.66–0.72 / 0.65–0.70; maximum width across hemelytra 1.12–1.35 / 1.25–1.27.

Bionomics. Although previous studies, including the original description, mentioned that E. nipponensis was collected under the bark of Pinus densiflora Siebold & Zucc. , almost nothing is known about the biology of the species, because of limited collection records (e.g., Hංඎඋൺ 1966, YൺඌඎඇൺGൺ 2001b). However, the meticulous field observations by MൺൾHൺඋൺ (2011) revealed that this species inhabits the fragmented, flake-like bark of young branches. Since his report, the species has been discovered mainly in the Tohoku district in the northern part of Honshu, where Japanese red pine forests are preserved in good condition over a wide area (Kඈඇඇඈ 2012a, 2020; MൺൾHൺඋൺ 2015). Thus, E. nipponensis has an undoubtedly strong association with P. densiflora . The population of P. densiflora seems to be decreasing in various parts of Japan owing to pine wilt disease and chemical spraying. Therefore, Japanese populations of E. nipponensis are currently designated as a Near Threatened Species Category in the Red-List by the Ministry of the Environment (Yൺආൺൽൺ 2015).

Distribution. Japan: Honshu: Aomori (Kඈඇඇඈ 2020), Miyagi (Kඈඇඇඈ 2012a), Yamagata (Kඈඇඇඈ 2012a), Tochigi (MൺൾHൺඋൺ 2009), Tokyo (Hංඎඋൺ 1966), Fukui (SHංආඈඇඈඒൺ 2001), Yamanashi (Hංඎඋൺ 1966), Nagano (Hංඎඋൺ 1966), Aichi (AඌൺHං et al. 2010), Hiroshima (NඈඓൺKං & NඈඓൺKං 2013); and Kyushu: Fukuoka (Hංඎඋൺ 1966). China: Liaoning (Bඎ & ZHൾඇG 2001). In Japan, this species is presently restricted to Honshu and Kyushu ( Fig. 18 ). Recent records are concentrated in the northern part of Honshu, such as Tochigi and the Tohoku district (Kඈඇඇඈ 2012a, 2020; MൺൾHൺඋൺ 2015).

Remarks. Nearly no information is currently available on the morphology of the female genitalia of Elatophilus because they had never been described and illustrated. The female genitalia of E. nipponensis are characterized by having the basal part of the copulatory tube being extremely expanded and bulbous with rugosities. This character state somewhat resembles that of Temnostethus distans . Similar traits have also been found in Anthocoris species (e.g., A. thibetanus Poppius, 1909 ) (Kൾ & Bඎ 2007). The similarity of the copulatory tube between these species in different genera implies that this structure varies greatly among species in the same genus. To the best of our knowledge, it seems difficult to define each genus of Anthocorini based only on female genitalia.

Figures

Fig. 1. Habitus, dorsal (A, C, E) and lateral (B, D, F) views. A–B – Temnostethus distans Kerzhner, 1973, female; C–D – T. mirificus sp. nov., holotype, male; E–F – Elatophilus nipponensis Hiura, 1966, male. Scale bars: 1.0 mm.

Fig. 2. Scanning electron micrographs of diagnostic characters of Japanese anthocorids. A – Temnostethus distans Kerzhner, 1973, female; B, D – T. mirificus sp. nov., female (B) and male (D), paratypes; C – Elatophilus nipponensis Hiura, 1966, female. A–C – ostiolar peritreme and evaporatorium, left lateroventral view; D – pygophore with paramere, lateral view. Abbreviations: eva ‒ evaporatorium; mf ‒ median furrow; op ‒ ostiolar peritreme; prm ‒ paramere; pyg ‒ pygophore.

Fig. 3. Male (A–C, E–G, I–K) and female (D, H, L) genitalia. A–D –Temnostethus distans Kerzhner, 1973; E–H – T. mirificus sp. nov., paratype; I–L – Elatophilus nipponensis Hiura, 1966.A, E, I – pygophore with paramere (ejaculatory bulb omitted), dorsal view; B–C, F–G, J–K – paramere, two different views; D, H, L – copulatory tube and sperm pouch (D, L, sperm pouch broken off), dorsal view. Abbreviations: ct ‒ copulatory tube; prm ‒ paramere; pyg ‒ pygophore; sp ‒ sperm pouch. Scale bars: 0.1 mm.

Fig. 18. Distribution of Temnostethus distans Kerzhner, 1973 (circles), T. mirificus sp. nov. (triangles), and Elatophilus nipponensis Hiura, 1966 (squares) in Japan. Filled symbols represent records based on specimens examined by us, open symbols represent literature records.