Acicnemis exilis Morimoto & Miyakawa, 1995

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 exilis Morimoto & Miyakawa, 1995

Figs 1, 6E 1–6 , 2 , 15

Type material examined

( Japan: 21; Taiwan: 3; Total: 24). Holotype. Japan: Kagoshima Prefecture: • Amami-Oshima, Naze , 27. V. 1978, T. Tsutsumi, bears red label reading “ (HOLOTYPE) Acicnemis exilis Morimoto et. Miyakawa, 1994 ”, ELKU, ELKU 2963 .

Non-type material.

Japan: Kagoshima Prefecture: • Jinushi-daimyojin, Satomura, Nakano-jima Island , 7–9. VII. 2019, S. Imada (2, KUM), JHL_AREV_595 , JHL_AREV_596 ; Okinawa Prefecture: • Hikawa, Yonaguni Island , 3. V. 2016, N. Tsuji (1, KUM), JHL_AREV_597 ; • Banna-koen, Ishigaki Island , 1. IX. 2015, J. Aoki (9, KUM), JHL_SYN_145 (dissected male), JHL_AREV_598 , JHL_AREV_599 , JHL_AREV_601 – JHL_AREV_605 ; • JHL_AREV_724 ; • Mt. Omoto-dake , 15–17. IV. 2014, S. Yamamoto (2, KUM), JHL_AREV_606 , JHL_AREV_607 ; • Southeast Botanical Gardens , Okinawa Island, 10–24. II. 2016 (1 dissected male, OIST), OKENT 0109018 ; • Chatan, Ireibaru , 26.32468°N, 127.75918°E, 11–25. XI. 2015 (1, OIST), OKENT 0105900 (GenBank accession number: PV 255629 ) ; • Nanjo, Tamagusuku , 26.32468°N, 127.75918°E, 9–23. IX. 2015, OKENT 0056923 (GenBank accession number: PV 255628 ) (1, OIST) ; • Sefa-utaki , Nanjo, 15–29. VII. 2016, (1, OIST), OKENT 0065625 ; near Hiji , Okinawa Island, 16. III. 2024, J. H. Lewis (1, OIST), JHL_AREV_998 ; • Banna-dake , Ishigaki Island, 20. VII. 1973, H. Takizawa (1, HUM), JHL_ACITAI_086 ; Taiwan • Wulai (near Taipei), 27. V. 1965, K. Morimoto (1 dissected male, KUM), JHL_AREV_624 ; • Kotosho Island , 13–15. VIII. 1968, H. Makihara (2, KUM), JHL_AREV_757 , JHL_AREV_758 .

Diagnosis.

Body length 2.1–3.0 mm. Covered in pale brown, white, and gray scales, with two white-scaled spots in the apical 1 / 2 of the elytra. Scutellum covered in yellow scales. Only odd elytral intervals with erect scales. Sclerolepidia small but protruding. Third tarsomeres distinctly emarginate. Pedon with lateral edges approx. parallel in dorsal view, but converging evenly into a rounded point. Internal sac without tuberculate or roughened musculature inside the aedeagus, but with a non-hooked protruding structure (unmodified in posterior 2 / 3, sclerotized in anterior 1 / 3) that reaches the tip of the temo (Fig. 6 E 1 – 2 ).

Distribution.

This small species occurs throughout the Ryukyu Islands (southern Kagoshima Prefecture and Okinawa Prefecture, Japan) as well as Taiwan.

Remarks.

This species appears to be closely allied with the similarly minute, long hind-legged Australian species Acicnemis meriones Pascoe, 1872 , A. arachnopus Hubenthal, 1919 , and the Sumatran species A. ambigua Hubenthal, 1919 ; however, phylogenetic analysis is required to confirm this. Preliminary observations suggest that some of the names in this group are synonyms.

Figures

Figure 1. Maximum likelihood tree of twelve Acicnemis species based on a 300 base-pair long CO 1 gene fragment constructed in IQ-TREE v. 1.6. 12 using a GTR + F + I + G 4 model. Branch support values represent standard nonparametric bootstraps (1000 replicates). Bootstrap values less than 75 are not displayed on the tree. The codes MEBLA 191-14, VVGPL 2845-15, and OWEVG 891-15 are BOLD Systems accession numbers, whereas all other codes are GenBank accession numbers. Associated Acicnemis weevil figures on the right of the tree are approximately to scale.

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 6. Aedeagi of Acicnemis. A 1–2. A. albofasciata (Ter-Minasian 1953); B 1–2. A. azumai Morimoto & Miyakawa, 1995; C 1–2), A. cryptica Lewis & Kojima, sp. nov.; D 1–2. A. dividicincta Morimoto & Miyakawa, 1995; E 1–2. A. exilis Morimoto & Miyakawa, 1995; F 1–2. A. kiotoensis Nakane, 1963; G 1–2. A. laeta Hubenthal, 1919; H 1–2. A. luteomaculata Morimoto & Miyakawa, 1995; I 1–2. A. maculaalba Roelofs, 1875; J 1–2. A. nobilis Hubenthal, 1919; K 1–2. A. nohirai Morimoto & Miyakawa, 1995; L 1–2. A. palliata Pascoe, 1872; M 1–2. A. postica Hubenthal, 1919; N 1–2. A. ryukyuana Lewis, 2023; O 1–2. A. sauteri Hubenthal, 1919; P 1–2. A. shibatai Voss, 1971; Q 1–2. A. shigematsui Morimoto & Miyakawa, 1995; R 1–2. Acicnemis sp. 1; S 1–2. A. squamata Lewis & Kojima, sp. nov.; T 1–2. A. suturalis Roelofs, 1875.

Figure 15. Acicnemis exilis Morimoto & Miyakawa, 1995 (OKENT 0065625). A. Lateral; B. Dorsal. Scale bar: 1 mm.