Stenoscelis gracilitarsis Wollaston, 1973

Stenoscelis gracilitarsis Wollaston, 1973 View in CoL

[Japanese common name: Matsu-kuchibuto-kikui-zômushi]

( Figs 44, 45 View FIGURES 40–47 , 58–62 View FIGURES 58–62 , 76 View FIGURE 74–77 & 90–92 View FIGURE 90–92 )

Stenoscelis gracilitarsis Wollaston, 1873a: 42 View in CoL (type locality: “Hiogo”); Csiki, 1936 (cataloged); Marshall, 1937 (in key); Konishi, 1956 (in key); Konishi, 1962 (in key); Nakane, 1963 (illustrated); Morimoto, 1983 (in key); Morimoto, 1984 (illustrated); Zhang, 1995 (in key); Kojima & Morimoto, 2004 (cataloged); Nakane & Morimoto, 2007 (illustrated); Hlaváč & Maughan, 2013 (cataloged); Kojima et al., 2016 (recorded from Akuseki-jima Is., Tokara Isls.); Alonso-Zarazaga et al., 2023 (cataloged).

Diagnosis. Stenoscelis gracilitarsis is very similar to S. matobai , S. reniformis , and S. ogasawarensis , but can be distinguished from them by the sclerotized structure on the subapical part of endophallus being ovate, flat, with a pair of short projection dorsally, and unseparated basally ( Figs 58–59 View FIGURES 58–62 ).

Redescription. Body length 2.9–3.6 mm; black, rather shiny; mouth parts, antennae, tarsi, and apical part of tibiae reddish brown; setae yellowish brown.

Rostrum 0.6–0.7 times as long as wide; dorsum convex; dorsal surface reticulate, rugosely punctate; punctures small, separated by interspace approximately 1–2 times as long as diameter; upper margin of scrobe directed to lower margin of eye; epistome with six long setae basally, with anterior margin obtusely projected at right side. Head with dorsal surface reticulate, smoothly punctate; punctures small, separated by interspace approximately 2–4 times as long as diameter; interocular area with a deep fovea; eye round, hardly convex.

Antennae with club subcircular, slightly wider than long; funicle 7-segmented, slightly longer than club.

Prothorax 0.8–0.9 times as long as wide, widest before base, gradually narrowed anteriorly, weakly sinuate laterally; anterior margin weakly sinuate in middle or not; subapical constriction distinct on lateral side, obsolete on dorsal side; disc reticulate, rugosely punctate; punctures medium, separated by interspace almost as long as or narrower than diameter.

Elytra 1.6 times as long as wide, 1.0–1.1 times as wide as and 2.0–2.1 times as long as prothorax, subparallel, conjointly rounded at apex; apex obtusely angulated in lateral view; striae rather deep, with medium punctures separated by interspace approximately 1–2 times as long as diameter; apical part of striae moderated, not dilated or reticulate; second stria distinctly separated from base; intervals somewhat convex, with an irregular row of small puncture; base of second to third or fourth interval rugosely punctate-granulate; apical half of ninth interval and tenth interval carinate; granules of intervals arranged in a single row, indistinct basally, distinct and conical on declivity; setae on declivity arranged irregularly in one or two rows, as long as or shorter than granules.

Aedeagal body 1.7 times as long as wide, 1.0 times as long as apodeme, weakly arcuate laterally, rapidly narrowed and strongly prolonged apically; apodeme attached laterally; endophallus with a large sclerotized structure on dorsal side of subapical part; the structure ovate, flat, with a pair of short projection on dorsal side, with long hairs, without separated part basally; tegmen without dorsal part and paramere, with distinct manubrium; spiculum gastrale gradually curved to right side entirely, not expanded apically; sternite VIII divided, with several long setae apically; without spinulate apical membranous area.

Spiculum ventral not bifurcate at base; spermatheca with cornu falciform; collum not developed; ramus not developed.

Distribution. Hokkaido, Honshu, Shikoku, Kyushu, Tsushima Is., Tokara Islands (Nakanoshima Is. and Akuseki-jima Is.), Amami-Ôshima Is., and Okinawa-jima Is. (The distributions in Hokkaido and Akuseki-jima Is. were not confirmed in this study).

Biological note. Sugimoto & Tado (2003) observed that adults of S. gracilitarsis bored tunnels in cut wood of Pinus desiflora Siebold et Zucc. , and larvae hatched and bred inside it. They also observed that adults and larvae were boring processed wood of Pinus radiata D.Don in a wood processing plant. Adults were also collected from dead trees of other Pinaceae : Pinus thunbergii Parl. , Pinus luchuensis Mayr , Abies firma Siebold et Zucc. ( Konishi, 1956; 1962; Morimoto, 1983; present study).

Type material. Holotype ( Figs 90–92 View FIGURE 90–92 ): 1 unsexed ( NHMUK), “ Japan. / G. Lewis / 1910-320” (white card); “ Stenoscelis / gracilitarsis, W” (white card); “type” (round label with red border); “ NHMUK015528845 About NHMUK ” (white card).

Non-type material. Japan: Honshu: [Mie Pref.]: 1 male, Mt. Fujiwara, Fujiwara City , 25.VIII.1989, H. Kojima leg. ( TUA); [Kyoto-Shiga Pref.]: 1 male, 1 unsexed, Mt. Hiei , from Abies firma Siebold et Zucc ., 16.VII.1961, Watanabe leg. ( KUM); [Osaka Pref.]: 1 male, Iwawaki , 19. V.1960, Y. Kimura leg. ( KUM); [Nara Pref.]: 1 male, 2 unsexed, Sakahara , collected from log for Lentinula edodes (Berkeley) Pegler. , 9.VIII.1979, K. Watanabe & E. Shibata leg. ( KUM); [Wakayama Pref.]: 1 male, Susami , 19.II.1980, T. Matoba leg. ( KUM); [Okayama Pref.]: 1 male, Ishitômaruyama, Bizen-shi , 14.III.1974, Yamaji leg. ( KUM); [Yamaguchi Pref.]: 1 male, 5 unsexed, Yoshiwa, Ube-shi , collected from pallet made of Pinus radiata D. Don , 25.VII.2000, H. Tado leg. ( KUM); Shikoku: [Ehime Pref.]: 1 male, 4 female, 5 unsexed, Ehime Prefectural Forest Experimental Station , 13.X.1986, K. Hara leg. ( KUM); 3 male, 1 female, 4 unsexed, Kanda , Hokujô-shi, emerged from dead tree of Pinus sp. , V.1979, em. 10. V.1980, Laboratory of Silviculuture leg. ( EUM); Kyushu: [Fukuoka Pref.]: 3 male, 3 female, 8 unsexed, Ikinomatsubara, Fukuoka-shi , 30. VI.1980, no collector data ( KUM); 1 male, Mt. Homan , near. Fukuoka, 21.XI.1954, H. Kamiya leg. ( KUM); [Kumamoto Pref.]: 1 male, 1 unsexed, Tôyô-son , collected from dead tree of Pinus thunbergii Parl ., 18.II.1975, K. Morimoto leg. ( KUM); 1 male, 1 unsexed, ditto, collected from dead tree of Pinus densiflora Siebold et Zucc . 10.IV.1975, K. Morimoto leg. ( KUM); [Kagoshima Pref.]: 1 male, 2 unsexed, Sata , collected from stumps of Pinus thunbergii Parl ., 25.X.1961, K. Morimoto leg. ( KUM); Tsushima: 1 male, 2 female, Mt. Ohoshi , 15.VII.1960, H. Kamiya leg. ( KUM); 1 male, 2 unsexed, Tsutsuzaki, Izuhara-cho , from dead tree of Pinus thunbergii Parl ., 23. V.2015, K. Morimoto leg. ( KUM); Tokara Isls.: Nakanoshima Is. : 4 male, 2 unsexed, emerged from Pinus luchuensis Mayr., III.1990 - V.1991 R. Iwata & H. Makihara leg., ( KUM); Amami-Ôshima Is.: 1 male, 2 female, 9 unsexed, Nase , 18. VI.1961, K. Yamada leg. ( KUM); 2 male, ditto, 23.VII.1961, K. Yamada leg. ( KUM); 1 male, Chuô-rindô, Uken-son , 29. VI.2007, K. Takahashi leg. ( KUM); 1 male, Uchijiro, Wadomari-chô , 8.VII.2018, T. Saeki leg. ( KUM); 1 male, Taken, Uken-son , 6.VII.2019, T. & N. Ohbayashi leg. ( EUM); Okinawa Is.: 1 male, 38 unsexed, Yona , 21. V.1964, K. Morimoto leg. ( KUM); 4 male, 12 unsexed, Kunigami , collected from Pinus luchuensis Mayr. , 18. VI.1964, S. Kuniyoshi leg. ( KUM); 1 male, 1 unsexed, Mt. Nekumachiji, Ohgimi-son , 17. VI.2006, K. Takahashi leg. ( KUM); 1 male, Nagodake , 10. V.2016, I. Matoba leg. ( KUM).

Remarks. Stenoscelis gracilitarsis was described based on a specimen collected from “pino quodam antique” or “old fir-tree”, which is supposed to be a Pinus or Abies tree ( Wollaston, 1873a), and has since been known as a species associated with dead Pinaceae trees ( Konishi, 1956, 1962; Nakane, 1963; Morimoto, 1983, 1984; Nakane & Morimoto, 2007). However, in this study, three new species, which are difficult to distinguish from S. gracilitarsis except by their male genitalia, were newly recorded from Japan, all associated with broad-leaved trees. As the genitalia of the holotype of S. gracilitarsis was not observed in this study, the concept of S. gracilitarsis in this study is not sufficiently confirmed morphologically. However, all specimens of “ S. gracilitarsis ” examined in this study were exclusively collected from Pinaceae trees, and the three new species from broad-leaved trees. Additionally, the distributions of S. matobai and S. ogasawarensis are significantly distant from the type locality of S. gracilitarsis, Hiogo (Hyogo Prefecture, Honshu). In this study, I tentatively conclude that the present species is S. gracilitarsis based on these evidences.