Stenoscelis matobai Inoue, 2025

Stenoscelis matobai Inoue sp. nov.

[New Japanese common name: Ishigaki-kuchibuto-kikui-zômushi]

urn:lsid:zoobank.org:act:ED400B3D-A8C2-4765-A31E-531A1033FB85

( Figs 40–41 View FIGURES 40–47 , 48–52 View FIGURES 48 –52 & 74 View FIGURE 74–77 )

Diagnosis. Stenoscelis matobai is very similar to S. reniformis , S. gracilitarsis and S. ogasawarensis , but can be distinguished from them by the sclerotized structure on the subapical part of the endophallus, with a large spatulate projection (figs 48–49) (with a pair of projections in the other species).

Description. Body length 3.5–4.1 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 shallow fovea; eye round, hardly convex.

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

Prothorax 0.8 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 1.6–1.7 times as long as wide, 1.0 times as wide as and 1.9–2.0 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 1.4 times as long as wide, 0.8 times as long as apodeme, subparallel, rapidly narrowed and weakly prolonged apically; apodeme attached laterally; endophallus with a large sclerotized structure on dorsal side of subapical part; the structure suborbicular, flat, with a large spatulate projection on dorsal side, with long hairs, with a separated part basally; tegmen without dorsal part and paramere, with distinct manubrium; spiculum gastrale gradually curved to right side apically, 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. Japan: Ishigaki Is.

Etymology. The scientific name of the new species is dedicated to the collector of type specimens, Mr. Isao Matoba.

Biological note. Type specimens emerged from a dead broad-leaved tree (Isao Matoba pers. comm.).

Type material. Holotype ( Figs 40 & 41 View FIGURES 40–47 ): male ( KUM), “ Yarabu-dake , Ishigaki Is., Japan, 9.V.2001, I. MATOBA leg.” (white card); “ ǟsDzė / Ḃäāa垣ª / 9 V 2001 / Matoba Isao leg.” (white card); “HOLOTYPE / Stenoscelis / matobai / des. S. Inoue, 2024” (red card) . Paratypes: Japan: Ishigaki Is.: 2 male, 3 female, Yarabu-dake , 1–3.I.2001, em. 9.V.2001 I. Matoba leg. ( KUM); 1 female, ditto, 1–3.I.2001, em. 7.VIII.2001 I. Matoba leg. ( KUM); 3 female, ditto, 1–3.I.2001, em. 11.IV.2002 I. Matoba leg. ( KUM) .

Remarks. In this study, three new species, Stenoscelis matobai , S. reniformis , and S. ogasawarensis , which are closely similar to S. gracilitarsis , were found in Japan. The four species share the unique well-developed sclerotized structure on the subapical part of the endophallus, and the shape of it is a very effective character to identify them. On the other hand, it is difficult to distinguish these species using characters other than the male genitalia, and previous records of S. gracilitarsis need confirmation. In identifying these four species, I identified only the female specimens collected with the male specimens, and excluded the other female specimens from the examined material.

The four species differ from the other Japanese species in the upper margin of the scrobe directed to the lower margin of eye. This character state was also shared by the seven Asian species: Stenocelis acerbus Zhang, 1995 , Stenoscelis cephalotes (Faust, 1898) , Stenoscelis foveatus Zhang, 1995 , Stenoscelis gedensis (Marshall, 1926) , Stenoscelis longifolia ( Stebbing, 1914) , Stenoscelis muricatus Wollaston, 1873 , and Stenoscelis muriceus (Champion, 1914) . At present, the two Chinese species, S. foveatus and S. acerbus , may be distinguished from the four Japanese species by the shape of the median lobe and the other species by the characters used for separating them from S. gracilitarsis in the key proposed by Marshall (1937).