Pilophorus erraticus Linnavuori, 1962

Yasunaga, Tomohide, Duwal, Ram Keshari & Nakatani, Yukinobu, 2021, Reclassification of the plant bug genus Pilophorus in Japan and key to the genera and species of Japanese Pilophorini (Hemiptera: Heteroptera: Miridae Phylinae), Zootaxa 4942 (1), pp. 1-40 : 9-11

Pilophorus erraticus Linnavuori, 1962

( Figs 2A ̅B, 11B, 12A̅B, 14E–K)

Pilophorus erraticus Linnavuori, 1962: 170 (n. sp., desc.); Schuh, 2002 –2013, online catalog; Aukema, 2018, online catalog; Urayama et al. 2019: 79, fig. 2C (faunal list); Yamamoto & Yasunaga, 2020: 81 (faunal list).

Pilophorus miyamotoi (nec Linnavuori 1961: 165): Yasunaga et al. 1993: pl. 5, fig. 9.

Material examined. Holotype (♂). JAPAN: Honshu, Shinano [Nagano Pref.], Karuizawa , 36.36, 138.55, 3 Aug 1959, S. Miyamoto ( AMNH) ( AMNH _ PBI 00140174 ) . Additional material. JAPAN: Hokkaido: Otaru City, Oshoro Shinto-shrine , 43.209, 140.861, 16 Aug 2001, A. Yamamoto, 1 ♂ ( OMO) ; Sapporo City, Ainosato , 43.167, 141.410, Ulmus davidiana , 24 Aug 2001, T. Ogita, 1 ♀ ( TYCN) ; same data except for date 6 Sep 2001, 1 ♀ ( TYCN) ; same locality, Maackia amurensis , 10 Aug 2001, T. Ogita, 1 ♂ ( TYCN) . Honshu : Tokyo, Meguro-ku , Tokyo Univ. Komaba Campus , 35.06006, 139.68521, 22 Jun – 15 Aug 2013, T . Ishikawa, 1 ♂ 4 ♀ ( TUA) . Kyushu : Nagasaki City , Nagasaki West High School , 32.765907, 129.859517, Ficus superba , 4 Jun 2020, T. Yasunaga, 4 ♂ 3 ♀ ( TYCN) (1 ♂ with USIs, 00380664) ; Nagasaki City, Kawaguchi Park , 32.766964, 129.863641, Zelkova serrata , 14 Jun 2018, T. Yasunaga, 3 ♀ ( TYCN) ; same data, except for date 6–10 Jun 2019, T. Yasunaga, 2 ♂ 2 ♀ ( TYCN) ; Nagasaki Pref., Tsushima Island, Izuhara Town, Isaribi Park , 34.2055, 129.2985, Artemisia sp., 25 Jun 2020, H. Asanabe, 1 ♀ ( TYCN) (00380665).

Rediagnosis. Recognized by its typical, antlike body shape of the genus ( Fig. 2 A–B); dark reddish brown general coloration; somewhat clavate segment II with apical part about 1.5 times as thick as base; slightly curved metatibia; C-shaped, rather broad endosoma with shortened, small median process ( Figs 11B , 14 J–K); thick-rimmed, ovoid sclerotized ring with a developed rim dorsally; and vestibular sclerite with a short, thumb-like projection leftlaterally ( Fig. 12A ).

Measurements. See Table 2.

Biology. This univoltine mirid is known to inhabit a variety of deciduous broadleaf trees, such as Betulaceae , Salicaceae and Ulmaceae hosts, in temperate and cold temperate climate zones ( Kerzhner, 1988). However, Urayama et al. (2019) and Yamamoto & Yasunaga (2020) recently suggested that P. erraticus is obviously expanding its distribution range from forest to urbanized zones, utilizing (usually deciduous) trees planted for gardening or landscaping. The latest investigation also recognized a subtropical broadleaf, Ficus superba , as an additional breeding host, that was planted at the front garden of NWHS (cf. Fukuda et al., 2020).

Discussion. This species and P. pseudoperplexus have been frequently confused with each other, due to the great similarity in coloration, size, dorsal vestiture pattern and emergence period of adult (cf. Fig. 2 A–D). However, both species are usually distinguished from each other by external characters alone (couplet 18 of the above key). The shape of endosomal median process ( Fig. 11B vs. 11C) and female genital chamber ( Fig. 12A vs. 12C) is also distinct in each species. The egg of P. erraticus ( Fig. 12B ) was also found to be evidently longer than that of P. pseudoperplexus ( Fig. 12E ).

Confirmed breeding hosts of P. erraticus range over various broadleaf trees of more than five plant families as mentioned in above checklist, whereas P. pseudoperplex appears host plant specific with its occurrence currently restricted to deciduous Quercus oaks.

Figures

FIGURE 2. Habitus images of Pilophorus spp., live individuals. A. P. erraticus ♂. B. P. erraticus ♀. C–D. P. pseudoperplexus ♂. E. P. nakatanii, holotype ♂. F. P. lucidus ♀.

FIGURE 11. Male endosoma (vesica) and endosoma of Japanese Pilophorus spp. A. P. choii (from Otaru). B. P. erraticus (Nagasaki). C. P. pseudoperplexus (Kanagawa). D. P.okamotoi (Tsushima Is.). E. P.satoyamanus n. sp. (Kochi).F. P.setulosellus n. sp. (Hiroshima). G. Same (Nara). H. P. setulosus (Sapporo, type locality, Salix). I. Same, (Shiretoko, Artemisia).

FIGURE 12. Female bursa copulatrix and eggs (B, E, H) of Japanese Pilophorus spp. A, C, F, K–L. Dorsal view. D, G, I, J, M. Ventral view, with vestibular sclerite (VES). A–B. P. erraticus (Nagasaki). C–E. P. pseudoperplexus (Otaru). F–H. P. satoyamanus n. sp. (Ibaraki). I. P. okamotoi (Tsushima Is.). J–K. P. setulosellus n. sp. (Hiroshima). L–M. P. setulosus (Asahikawa).

FIGURE 14. Scanning electron micrographs for Japanese Pilophorus spp., males (except for E, L, P: ♀). A–D. P. choii. E–K. P. erraticus. L–N. P. pseudoperplexus. O–Q. P. miyamotoi. A, E. Left-dorsolateral habitus. B, I, N. Apex of pygophore, left lateral view. C–D, J–K, Q. Endosoma (vesica).A, E. Dorsal habitus. F. Thoracic pleura, left lateral view. H, L, M, O, P. Lateral habitus. G. Pygophore, dorsal view.