Acicnemis koguma Lewis & Kojima, 2025

Lewis, Jake H., Kojima, Hiroaki & Campbell, Erin O., 2025, A Japan-focused review of East Asian Acicnemis Fairmaire, 1849 (Coleoptera, Curculionidae) reveals cryptic diversity in a well-studied region, ZooKeys 1259, pp. 103-167 : 103-167

Acicnemis koguma Lewis & Kojima sp. nov.

Figs 2 D , 3 C , 17

Type material examined

( Japan: 3). Holotype. Japan: Wakayama Prefecture: • Mt. Otoh , 20. VII. 1980, I. Matoba, bears a red holotype label reading “ HOLOTYPE / Acicnemis koguma / Lewis & Kojima, 2025 ”, JHL_DNA_143 , female, deposited in KUM . Paratypes. Japan • Tokyo Metropolis: Mt. Takao , 12. VIII. 1969, H. Fujita, LBM accession # 5128 (1, LBM), JHL_SYN_141 ; • Mt. Takao , 3–4. VII. 1965, K. Sakai (1, CMIC), CBM-ZI 68474 .

Diagnosis.

Body length 4.5–7.0 mm. Covered in pale and dark brown scales, with two obliquely shaped pale brownish, black-bordered spots across middle of elytra. Second funicular antennomere shorter than funicular antennomeres 3 + 4 (Fig. 2 D ) (longer in A. kiotoensis ). Pronotum with impunctate longitudinal midline (absent in A. kiotoensis ). Scutellum large (somewhat narrower than A. kiotoensis ) and bare dorsally but bordered laterally by pale yellow scales (Fig. 3 C ). Only odd elytral intervals with erect scales (some erect scales on 2 nd interval in apical fifth of elytra) ( A. kiotoensis with erect scales on the 2 nd elytral interval). Sclerolepidia indistinct, forming low, rounded, non-protruding tubercles. Third tarsomeres truncate (emarginate in A. kiotoensis ).

Distribution.

This rare species is only known from two localities in mainland Japan, Mt. Takao ( Tokyo Metropolis) and Mt. Otoh ( Wakayama Prefecture).

Etymology.

The specific name koguma means little bear in Japanese, and is a reference to the apparent mountain-loving preference and small, brown nature of this rarely observed weevil species. We also suggest the Japanese common name コグマカレキゾウムシ [Koguma-kareki-zoumushi], which in English means “ Little-bear-dead-tree-weevil ”.

Remarks.

This cryptic species was clearly overlooked due to its remarkable similarity with A. kiotoensis in overall color and appearance, but differs consistently in the five characters listed in the diagnosis. The male remains unknown.

Figures

Figure 2. Diagnostic morphological characters in Acicnemis. A. A. azumai Morimoto & Miyakawa, 1995 (JHL _ ACITAI _ 081) showing lack of prominent posterior prosternal projections; B. A. laeta Hubenthal, 1919 (JHL _ AREV _ 533) showing prominent prosternal projections; C. A. kiotoensis Nakane, 1963 (JHL _ AREV _ 982) showing antenna with the second funicular antennomere longer than antennomeres 3 + 4; D. A. koguma Lewis & Kojima, sp. nov. (JHL _ SYN _ 141) showing antenna with the second funicular antennomere shorter than antennomeres 3 + 4; E. A. luteomaculata Morimoto & Miyakawa, 1995 (JHL _ AREV _ 189) showing truncate third tarsomere; F. A. ryukyuana Lewis, 2023 (JHL _ ACI _ 011) showing weakly emarginate third tarsomere; G. A. maculaalba Roelofs, 1875 (JHL _ AREV _ 577) showing strongly emarginate third tarsomere.

Figure 3. Scutella and pronota of various Acicnemis species. A. A. azumai Morimoto & Miyakawa, 1995 (JHL _ ACITAI _ 081) showing two bare (unscaled) tubercles baso-medially on the pronotum; B. A. kiotoensis Nakane, 1963 (JHL _ AREV _ 982) showing a broad, unscaled scutellum; C. A. koguma Lewis & Kojima, sp. nov. (JHL _ SYN _ 141) showing a bare, but more slender scutellum than A. kiotoensis; D. A. maculaalba Roelofs, 1875 (JHL _ AREV _ 577) showing a small scutellum covered in scales; E. A. palliata Pascoe, 1872 (JHL _ AREV _ 779) showing a larger scutellum that is shiny and bare dorsally, and surrounded along the perimeter by yellow scales; F. A. shigematsui Morimoto & Miyakawa, 1995 (JHL _ ACITAI _ 052) showing a smaller scutellum covered in scales.

Figure 17. Acicnemis koguma Lewis & Kojima, sp. nov. (JHL _ SYN _ 141). A. Lateral; B. Dorsal. Scale bar: 1 mm.