Malthodes okushimai Imasaka & N. Takahashi, 2020

Takahashi, Naoki & Imasaka, Shôichi, 2020, Two new species and a new distribution record of the genus Malthodes Kiesenwetter (Coleoptera: Cantharidae) from Japan, with notes on the male and female abdominal morphology, Zootaxa 4778 (2), pp. 357-371 : 363-366

Malthodes okushimai Imasaka & N. Takahashi , sp. nov.

( Figs. 7–9 , 19–24 , 31 )

Malthodes sp. 4: Imasaka et al., 1990: 11; Imasaka & Nakamura, 1993: 56; Imasaka & Nakamura, 1997: 52; Imasaka, 2013: 102.

Type materials. Holotype (deposited in KURA collection), male, Japan, Honshu, Okayama Pref., Kamogawa-cho, Ukan-kei , 12.iv.1998, Y. Okushima leg.

59 Paratypes (37 males and 22 females): HONSHU (Hyôgo Pref.) Mt. Ôginosen , 21.v.1999, Y. Okushima leg. (1 male, KURA). (Okayama Pref.) Mt. Sangajô , 16.v.1976, O. Yamaji leg. (1 male and 1 female, SIC) ; 9.v.1987, O. Yamaji leg. (1 male, SIC) . Kamogawa-chô, Kegi Shrine , 7.v.1995, A. Watanabe leg. (1 male, KURA) . Yubara-chô, Yumoto , 7.v.1995, A. Watanabe leg. (2 males, KURA) . Kamogawa-chô, Ukan-kei , 12.iv.1998, Y. Okushima leg. (1 male, KURA) ; 19.iv.1998, Y. Okushima leg. (1 male, KURA) . Mt. Gagyû , 29.iv.1974, O. Yamaji leg. (1 male and 1 female, SIC) ; 9.v.1990, O. Yamaji leg. (1 female, SIC) ; 12.v.1996, Y. Okushima leg. (1 male and 1 female, KURA) . Aida Town, Takinomiya , 5.v.1988, A. Watanabe leg. (2 males and 1 female, SIC) . Nagi-chô, Takiyama , 16.v.1987, O. Yamaji leg. (1 male and 1 female, SIC) . Yoshinaga-chô, Hattôji , 16.v.1993, A. Watanabe leg. (1 female, KURA) . Kamo-chô, Sumiyama , 6.v.1993, S. Takeuchi leg. (1 male, KURA) . Okutsu-chô, Okutsukawanishi , 17.v.1995, Y. Okushima leg. (1 male, KURA) . Soja City, Minobe , 13.iv.1998, Y. Okushima leg. (1 male, KURA). (Hiroshima Pref.) Itsukushima Is., 26.iv.1988, SI. (10 males and 6 females, SIC) . Yoshiwa Vil., Juppôzan-rindô , 24.v.1988, SI (1 male, SIC). (Tottori Pref.) Mt. Mitoku , 5.v.2000, H. Mitsueda leg. (1 male, HMC). (Shimane Pref.) Mt. Sanbe , 29.iv.1992, T. Shimizu leg. (1 male, KURA) . < Oki Isls.: Dôgo Is.> Fuse-mura, Washigamine , 16.v.2003, T. Shimada leg. (2 males and 2 females, KURA) . Saigô-chô, Mura Tunnel , 4.v.2003, H. Kadowaki leg. (4 males and 2 females, KURA) . Saigô-chô, Ôku , 12.v.2003, T. Shimada leg. (1 male and 2 females, KURA) . Saigô-chô, Mt. Daimanji (430 m alt.), 18–25.v.2004, T. Shimada leg. (1 female, KURA) . Okinoshima-chô , Dagyô-no-taki (350 m alt.), 23.v.2005, T. Shimada leg. (1 female, KURA). (Yamaguchi Pref.) Tokuyama City, Sakaedani , 22.iv.1988, SI (1 male, SIC) . Shimonoseki City, Gesan , 30.v.2006, Y. Okushima leg. (1 female, KURA) .

Diagnosis. Body ( Figs. 7–8 ) relatively large, dark brown to black. Male: abdominal tergite X ( Fig. 19 ) hooked with round apices in latero-ventral portions in profile; abdominal sternite IX ( Fig. 20 ) robust, subparallel at sides in basal part, subrectangularly dilated in apical part in ventral view. Aedeagus ( Figs. 22–24 ): basophyses of tegmen curved medially in apical portion, narrowed and swollen around apex, concave behind apical swollen part; penis slender, sublinear and extending around apices of basophyses. Female: copulatory depression hardly recognized on any abdominal tergite; abdominal tergite VIII subrectangular and 1.51–1.84 times wider than long. Ovipositor ( Fig. 31 ): coxite subrectangular, rounded at apical angles, subtly produced medially at inner apical angle.

This new species is very similar to M. kyushuensis Takakura, 1988 in general appearance, but can be distinguished by the subrectangulate apical part of male abdominal sternite IX without a pair of projections and the slenderer basophyses of tegmen in the aedeagus.

Description. MALE ( Fig. 7 ). Head black but slightly brownish around clypeus; eyes dark brown to dark brownish black; mandibles and pretarsal claws reddish brown but often yellowish in basal parts of mandibles; pronotum, scutellum, elytra, ventral side of thorax, and most of abdomen dark brown, though usually darker on pronotum, scutellum and elytra, somewhat reddish on metasternum and abdominal tergite X, and light orangish yellow on abdominal sternite IX and tergite X; maxillary and labial palpi, antennae, and legs dark brown but slightly and more brownish, and often yellowish on trochanters, basal parts of tibiae and tarsomeres 4 and 5; mouth parts other than the aforementioned parts yellowish.

Body elongate, densely covered with dark brownish and recumbent pubescence, but covered with lighter pubescence on abdominal tergite IX, fitted with longish pubescence around clypeus and at posterior margin of abdominal sternite VIII; antennae, tibiae, tarsi, and abdominal sternite IX covered with suberect bristles, which are slightly light-colored on the latter part.

Head wider than long, 1.06 (1.04–1.16) times wider than pronotum; surface relatively lustrous; mandibles finely serrulate on incisor edges; eyes relatively large, interocular distance 1.43 (1.43–1.59) times larger than radius of eye; antennae filiform, relatively long, reaching around basal 9/10 of elytra, relative lengths of antennomeres from base as follows:—16.1: 10.0: 12.2: 15.5: 17.0: 17.3: 16.6: 15.7: 15.0: 14.2: 15.5.

Pronotum subrectangular, 1.52 (1.39–1.53) times wider than long; disc slightly convex medio-dorsally, with a lanceolate depression in medio-longitudinal area and a reniform depression along each lateral margin, weakly depressed along posterior margin except medial area, relatively lustrous though somewhat matt on lateral depressed areas and hypomera, subtruncate but arcuate on both sides at anterior margin, obliquely truncate and feebly warped dorsally at front angles, gently arcuate posteriorly at posterior margin, slightly produced laterally at hind angles, shallowly emarginate medially and feebly dilated posteriorly at sides.

Elytra 2.91 (2.66–3.00) times longer than wide; surface slightly rugulose though relatively smooth in basal and apical portions, somewhat lustrous in basal areas, weakly marginate along sutural line, with a few rather undefined costae on each elytron.

Prosternum, meso- and metaventrites, posterior portions of metanepisterna lustrous; mesanepisterna, mesepimera, anterior portions of metanepisterna slightly matt.

Most of abdominal sternites lustrous and faintly rugulose; abdominal tergite IX subquadrate, gently arcuate basally at basal margin, subparallel in basal half and narrowed apically in apical half at sides, subtruncate but feebly emarginate in the middle at apical margin in dorsal view, convex medio-dorsally, weakly depressed on surface in latero-basal areas, semi-obovately emarginate at apico-ventral margin, and hooked at apico-ventral angles in profile; tergite X ( Fig. 21 ) subrectangular, shallowly emarginate at apical margin, rounded at apical angles, narrowed around the base, depressed on surface on both sides at base in dorsal view, convex medio-dorsally, and hooked with round apices in ventro-lateral portions in profile; sternite IX ( Fig. 20 ) robust in general appearance, well sclerotized, convex medio-ventrally and subparallel at sides with a medio-longitudinal depression in basal part but dilated basally around the base, subrectangularly dilated in apical part and curved dorsally in lateral areas in ventral view, arcuate ventrally in basal part and prolonged dorso-posteriorly in profile, with a longitudinal carina aroud the middle of apical dilated part on dorsal surface.

Aedeagus ( Figs. 22–24 ) stout, nearly obovate in outline in dorsal view: sternal lobe of tegmen subquadrate, shallowly emarginate at apical margin, strongly constricted just behind rotundate apical angles at sides, and obtusely protruded on both sides at basal margin near the base of processus laminae basalis (sensu Verhoeff 1894) in ventral view, slightly convex medio-ventrally but more clearly so in basal part, curved dorsally in lateral areas, and arcuate dorsally at lateral margins behind constrictions in profile; tergal platelet of median lobe U-shaped in appearance, slender and feebly curved laterally in each apical half in dorsal view; tergal lobe of tegmen somewhat elliptical in outline, depressed in apical marginal area, faintly bisinuate at apical margin, strongly narrowed basally at sides around the base of basophyses, rotundate at base, concave medio-ventrally though swollen medio-dorsally in basal part, and covered with longish setae in apical part except apical marginal area in dorsal view; basophysis of tegmen relatively slender and flattened, subparallel in dorsal view though curved medially in apical portion, narrowed and swollen around apex, concave behind apical swollen part, with an obtuse projection behind apex at mesal margin; penis slender, sublinear and extending around apices of basophyses.

Body length: 4.1 (3.3–4.9) mm; width: 1.0 (0.8–1.3) mm.

FEMALE ( Fig. 8 ). Almost similar to male, but body often slightly stouter and darker in coloration than in male; apical abdominal segments almost dark brown. Head slightly narrower than in male; eyes smaller than in male, interocular distance 2.87–3.16 times larger than radius of eye; antennae shorter, slightly extending over basal halves of elytra, relative lengths of antennomeres from base as follows:— 17.0: 10.0: 10.6: 13.3: 13.8: 13.3: 12.6: 12.1: 11.6: 10.9: 13.5. Pronotum ( Fig. 9 ) 1.33–1.45 times wider than long, and 1.07–1.19 times wider than head; disc less emarginate medially at sides and evener than in male. Elytra 2.45–3.26 times longer than wide.

Copulatory depression hardly recognized on any abdominal tergite; tergite VI subrectangular and gently convex medio-dorsally but dilated apically in basal half, minutely and densely granulate in basal area (observed under macerated condition) in dorsal view; tergite VII broad, subtrapezoidal, dilated apically, rounded and slightly produced latero-apically at apical angles, and gently convex medio-dorsally on dorsum; tergite VIII subrectangular and faintly narrowed apically, 1.51–1.84 times wider than long, subtruncate but sometimes subtly sinuate at apical margin, widely rounded at basal angles, rounded at apical angles in dorsal view, convex medio-dorsally though feebly depressed along basal margin in profile.

Ovipositor ( Fig. 31 ): coxite subrectangular, rounded at apical angles, subtly produced medially at inner apical angle, slightly warped ventrally at base with a small lapel reaching basal 2/3 of coxites at medial end in ventral view; paraproct semicylindrical, narrowed in about apical 2/5, reaching or slightly extending over apices of coxites in ventral view, shallowly emarginate at apical margin in dorsal view; proctiger semicylindrical, gradually narrowed in basal part though more clearly so in apical part, extending over apices of coxites by more than the length of coxites in ventral view.

Body length: 3.2–4.0 mm; width: 0.9–1.0 mm.

Distribution. Japan: western Honshu and Oki Isls.

Infraspecific variation. The male abdominal sternite IX is sometimes not so strongly produced laterally at the basal angles in the dilated apical portion where a longitudinal carina is somewhat variable in clarity on the dorsal surface. Coxite of the ovipositor is slightly variable in outline and somewhat tapered medially at the inner apical angle in some cases.

Etymology. This specific epithet is given in honor of our colleague, Dr. Yûichi Okushima, a specialist in Cantharidae taxonomy and a collector of materials examined here. We propose that the Japanese name of this new species is “Okayama-kurochibi-jôkai”.

Figures

FIGURES 1–9. Habitus of Malthodes spp. 1–3, Malthodes morimotoi Imasaka & N. Takahashi, sp. nov.; 4–6, M. parvus Kazantsev; 7–9, M. okushimai Imasaka & N. Takahashi, sp. nov.; 1, 4, 7, males; 2, 5, 8, females; 3, 6, 9, female pronota. Scales: 1.0 mm (Figs 1–2, 4–5, 7–8); 0.2 mm (Figs 3, 6 and 9).

FIGURES 19–24. Malthodes okushimai Imasaka & N. Takahashi, sp. nov., male. 19, apical portion of abdomen, lateral view; 20, abdominal sternite IX, ventral view; 21, abdominal tergite X, dorsal view; 22–24, aedeagus (22, dorsal view; 23, lateral view; 24, ventral view). The arrow representations are the same as those in Figs 10–15 (one in the upper margin for Fig. 19; the other one in the right margin for Figs 20–24). Abbreviation: plb, processus laminae basalis. Scales: 0.2 mm (Figs 19–21); 0.1 mm (Figs 22–24).

FIGURES 31–32. Ovipositors of Malthodes spp., ventral view. 31, Malthodes okushimai Imasaka & N. Takahashi, sp. nov.; 32, Malthodes parvus Kazantsev. The arrow representation is the same as that in Figs 11–15. Abbreviation: p, proctiger. Scales: 0.2 mm.