Neomecopus subarmatus Hustache, 1921

Fujisawa, Yusuke, Yoshitake, Hiraku & Kojima, Hiroaki, 2025, Weevils of the genus Neomecopus Hustache, 1921 (Curculionidae: Conoderinae: Mecopini), with description of a new species from the Ryukyus, Japan, Zootaxa 5631 (3), pp. 574-584 : 577-581

Neomecopus subarmatus Hustache, 1921

[Japanese name: Shirafu-kumo-zômushi]

( Figs 5, 6, 8, 9 , 11 , 13–15 , 19–26 , 31–35 )

Neomecopus subarmatus Hustache, 1921: 92 (type locality: “Ibuki prés Gifu ”); Hustache, 1934: 42 (cataloged; “ Japon ”); Morimoto, 1962a: 199 (cataloged; Japan: Honshu, Kyushu); Morimoto, 1984: 321, pl. 63, fig. 15 (habitus photo); Morimoto, 1989: 515 (in checklist; Honshu, Kyushu); Alonso-Zarazaga & Lyal, 1999: 112 (cataloged); Kume, 1999: 14 (Shikoku); Kojima & Morimoto, 2004: 107 (cataloged; Japan); Matoba, 2008: 14 (on Picrasma quassioides ); Nakamura, 2009: 47 (on P. quassioides ); Lyal, 2013: 216 (cataloged); Alonso-Zarazaga et al., 2017: 167 (cataloged; Japan); Kuroda, 2017: 36 (on P. quassioides ); Hokkaido, 2019: 44 (in checklist; Hokkaido); Alonso-Zarazaga et al., 2023: 166 (cataloged; Japan); Fujisawa, 2023: 11 (biological note & distribution range).

Diagnosis. This species is characterized by the following features: forehead between eyes with glabrous part at middle; rostrum moderate in length, 1.3–1.5 times as long as pronotum in male; posterior margin of scutellum simple, not notched; punctures of elytral striae not squamous; metepisternum with large patch of black scales on basal 2/3; metafemora each with black scaly patch on apical 1/3; metatibiae each with black scaly patches at basal 1/3 and apical 1/5, respectively. Male endophallus with anchor-shaped sclerite, which is about 1/3 as long as its length.

Redescription. Male. Length: 4.6–5.9 mm; width: 1.9–2.5 mm.

Derm black; antennae, tibial unci, and tarsi reddish brown.

Head covered with narrow yellowish grey scales on basal and apical parts of forehead between eyes and genae. Rostrum covered with yellowish gray narrow to linear scales from base to level between antennal insertions. Pronotum mainly covered with dark narrow scales, with three paler markings set as follows: transversely rhomboidal open macula of yellowish gray narrow scales on disk; longitudinal lateral stripes of yellowish gray narrow scales, which are slightly arched externally at basal 1/3 and then narrowed apically; and three small patches of imbricate yellowish white lanceolate scales at basal angles and ante-scutellar part. Scutellum covered with dense yellowish white lanceolate scales, which become imbricate on apical half. Elytra irregularly mottled with black, white and yellowish gray narrow scales, except yellowish white post-scutellar patch composed of imbricate lanceolate scales and longitudinal patch that is located at basal 1/6 of suture and 2.5 times as long as wide. Femora and tibiae mainly clothed with yellowish gray narrow scales; profemora immaculate; meso- and metafemora each bearing black scaly spot at apical 1/3; each tibia with black scaly spots at base and apex. Underside mainly covered with dense yellowish white lanceolate scales, except metepisterna each with black scaly patch at basal 2/3 and metasternum with large lateral patches of black scales; patches on metepi- and metasterna contiguous, forming large black patch on each side ( Fig 11 ).

Head finely and closely punctate. Rostrum 1.3–1.5 times as long as pronotum; dorsum closely punctate, with five weak carinae: median one extending from base to subapical part, which is surrounded by two shorter carinae on each side; lateral carinae extending from base to apical 1/3. Antennae inserted at apical 1/3 of rostrum; scape almost as long as funicle and club segment I combined; funicle gradually widened apicad, with segment I about twice as long as II, II 1.3 times as long as wide and 1.5 times as long as III, III to VI much shorter than II, subequal in length to each other.

Prothorax 1.4–1.6 times as wide as long, widest at middle. Scutellum simple, rounded posteriorly. Elytra 1.2–1.3 times as long as wide; intervals I to III weakly depressed on basal 1/4; III and V each with row of pointed granules; striae with punctures devoid of scale. Legs relatively slender; profemora slightly stouter than mesofemora, each armed with small triangular tooth; metafemora as thick as front pair, each with larger tooth than that on front pair ( Figs 13–15 ).

Prosternum with minute spines, each of which is lower than height of procoxae in profile. Metasternum and ventrite I widely conjointly depressed on middle. Venter with ventrites II to IV flat at middle; ventrite V with weak round depression on middle of apical half.

Terminalia as illustrated ( Figs 19–22 ); sternite VIII paired, achaetous along caudal margin, with pair of median sclerites, with spiculum gastrale about 0.8 times as long as aedeagus; tegmen with apodeme about half length of tegminal ring; aedeagus with apodemes nearly as long as body; endophallus with following sclerites: 1) anchor-shaped sclerite ranging from base to basal 1/3, 2) long sclerite extending from about basal 1/3 to apical 1/3 on along midline, rounded at apex, 3) two shorter sclerites surrounding median one, which extends from middle to apical 1/3 and is pointed at apex.

Female. Length: 4.9–6.6 mm; width: 2.0– 2.8 mm.

Rostrum slightly more slender, 1.6–1.7 times as long as pronotum, with shorter median carina not reaching apical 1/3, smoother on apical half. Antennae inserted slightly beyond middle of rostrum. Prosternum with smaller spines. Metasternum and ventrites I to V weakly convex.

Terminalia as illustrated ( Figs 23–26 ); sternite VIII with apodemes 1.5 times as long as apical plate; common oviduct partially sclerotized; spermatheca comma-shaped, ramus and collum less marked; spermathecal duct short; insertions of duct and gland close to each other.

Otherwise as in male.

Specimens examined. [Hokkaido] 1 male and 1 female, Mt. Maruyama , Sapporo City, Hokkaido, 21. VI.1992, H. Shito ( TUA). [Honshu] 17 exs., Tanaka, Tôgane City , Chiba Pref., 22. VI.2024, H. Yoshitake, on a stand dead tree of Picrasma quassioides (PCHY) . 1 male, Shimobe , Yamanashi Pref., 13. V. 2000, T. Kobayashi ( TUA) . 2 males and 2 females, Asashina, Saku City , Nagano Pref., 23.IV.2019, J. Kaneko ( TUA) ; 14 males and 11 females, 27. V.- 1. VI.2019, H. Kojima ( TUA; 2 males and 3 females dissected). [Kyushu] 1 female, Mt. Nakadake, Kiurauchi, Ume Town , Saiki City , Oita Pref., 23. IV.2016, H. Tatsukawa ( TUA) .

Distribution. Japan (Hokkaido, Honshu, Shikoku, and Kyushu).

Biological note. Adults were mainly collected from damaged trees of Picrasma quassioides ( Simaroubaceae ; Nigaki in Japanese). Matoba (2008) collected 15 adults from a logged P. quassioides tree. Nakamura (2009) collected an adult from the underside of a leaf and Kuroda (2017) collected two adults by sweeping the tips of branches of living P. quassioides trees.

The third author found a number of adults on the trunk of a damaged tree of P. quassioides in Nagano Prefecture. He observed agonistic behavior between males, mating behavior, and act of an individual making a hole in the bark of the trunk by using its rostrum ( Figs 31–33 ).

The second author found a number of adults on a stand dead tree of P. quassioides ( Figs 34, 35 ). He also observed mating behavior and acts of several individuals making holes in the bark of a trunk of the tree.

Figures

FIGURES 5–10. Habitus images of Neomecopus spp. 5–7, Dorsal habitus; 8–10, lateral habitus. 5 & 8, N. subarmatus, male; 6 & 9, ditto, female; 7 & 10, N. tamaderai sp. nov., male.

FIGURES 11, 12. Male undersides of Neomecopus spp. 11, N. subarmatus; 12, N. tamaderai.

FIGURES 13–18. Femora and tibiae of Neomecopus spp., in ventral view. 13–15, N. subarmatus; 16–18, N. tamaderai. 13 & 16, front legs; 14 & 17, middle legs; 15 & 18, hind legs.

FIGURES 19–26. Male and female terminalia of Neomecopus subarmatus. 19–22, Male; 23–26, female. 19, Aedeagus, dorsal; 20, ditto, lateral; 21, tegmen; 22, sternite VIII and spiculum gastrale; 23, tergite VIII; 24, sternite VIII; 25, ovipositor; 26, spermatheca.

FIGURES 31–35. Ecology of Neomecopus subarmatus. 31, An adult pair on the bark of a damaged tree of Picrasma quassioides; 32, a rival male (RM) attacking a mate guarding male (MGM) from the front (FM: female) (indicated by arrows); 33, two adult pairs (arrows) on the trunk of a damaged tree of P. quassioides; 34, a stand dead tree of P. quassioides; 35, an old adult on the trunk of a stand dead tree of P. quassioides.