Malthinus mucoreus Kiesenwetter, 1879

Takahashi, Naoki, 2010, Notes on Malthinus mucoreus (Coleoptera: Cantharidae), with descriptions of two new related species from the Ryukyus, Southwest Japan, Zootaxa 2563, pp. 53-68 : 54-60

Malthinus mucoreus Kiesenwetter, 1879

(Japanese name: Kurosuji-tsumaki-joukai) ( Figs. 1–4 , 9–27 )

Malthinus mucoreus Kiesenwetter, 1879: 309 (type in the Natural History Museum, London, not examined); Wittmer, 1955: 41 (in key); Nakane, 1963: 173, pl. 87, fig. 6; Delkeskamp, 1977: 343 (in list); Imasaka et al., 1981: 293 (in list); Imasaka & Abiru, 1985: 6 (in list); Satô, 1985: 116, pl. 19, fig. 13; Imasaka, 1989: 16; Takahashi, 1998: 45 (in list); Kazantsev & Brancucci, 2007: 281 (in list).

Redescription. MALE. Body chiefly reddish yellow to yellowish orange with some dark-coloured parts; elytra and ventral side of body somewhat paler with apical portions of elytra palish yellow; antennae, particularly the apical three-fourths, and metaventrite except for lateral areas sometimes darker; eyes black; vertexal marking on head, medio-longitudinal area of pronotum, scutellum, elytron except for basal and mesal areas and ventral margin of epipleuron brownish black, but somewhat more brownish on scutellum and more grayish on blackish area of each elytron; vertexal marking on head somewhat transverse elliptical or roundly trapezoidal in anterior part, narrowed posteriad and extended to posterior end of head, blurred on the border; apical halves of mandibles, tibial spurs and tarsal claws reddish brown, and sometimes so at front angles of prothoracic epipleura; 4th tarsal segments and rarely the adjacent parts dark brownish; venter except for last two segments and lateral areas on each abdominal sternite often dusky.

Body elongate, mostly and densely covered with pale brownish and recumbent pubescence, but provided with longish pubescence around clypeus; elytra a little more densely covered with pubescence than in head and pronotum; antennae and elytra intermingled with faintly darker bristles; legs covered with darker bristles; last abdominal sternite covered with darker and longish bristles in apical area.

Head somewhat broader than long, 1.41–1.61 times as wide as pronotum, gently convex dorsad, narrowed posteriad behind eyes, faintly furrowed medio-longitudinally in posterior area which is often hidden under the anterior margin of pronotum, somewhat flattened before vertex, feebly swollen mesad around antennal pits, weakly depressed apicad just before antennal sockets, gently arcuate at apical margin of clypeus; surface puncticulate and lustrous before antennal pits, rugulose in posterior area though somewhat smoother before vertex, matt just before anterior margin of pronotum on dorsum, finely granulate and matt on ventral side but almost impunctate and lustrous on stipes of maxillary palpi; eyes medium in size, semiglobular and prominent laterad, interocular distance 3.12–3.69 times as large as radius of eye; antennae filiform, reaching about basal 11/15 of elytra, 1st segment subclavate, 2nd somewhat subclavate, 3nd to 11th subcylindrical, and relative lengths of antennal segments from base as follows—19.6: 11.6: 11.9: 14.3: 14.7: 14.6: 13.8: 13.4: 11.5: 10.5: 11.4.

Pronotum subquadrate, 0.93–1.09 times as long as wide; disc mostly granulate though slightly rugulose on blackish marking, convex medio-dorsad, transversely swollen from side to side at middle, elevated in medioposterial area but slightly hollowed in the middle, subtruncate or faintly arcuate anteriad at anterior margin, obliquely narrowed apicad at front angles, obtusely rounded at hind angles, weakly arcuate posteriad but shallowly emarginate in the middle and feebly marginate at posterior margin; lateral margins subparallel behind front angles in anterior parts, obtusely or roundly and slightly protruded laterad at middle, and shallowly emarginate mesad before hind angles. Scutellum subtrapezoidal and narrowed posteriad, covered and fringed with fine pubescence.

Elytra 2.56–2.98 times as long as wide; each surface rugulose with a few vague costae but smoother around humerus and apex, weakly marginate along sutural line, longitudinally punctate in rows, particularly so in mesal area, the punctures becoming indistinct distad in other area. Legs moderately slender and simple; all claws simple; relative lengths of metatarsal segments from base as follows—15.7: 8.2: 5.6: 7.0: 7.4.

Meso- and metaventrites puncticulate and lustrous on their surfaces. Venter except for 9th abdominal sternite relatively smooth and lustrous but somewhat rugulose, and sometimes matt along posterior margin on each sternite other than last two segments; 8th sternite widely, roundly but somewhat trapezoidally emarginate at posterior margin; 9th relatively thin, arcuate along ventral surface of basal piece of genitalia in profile, mostly somewhat granulate and matt on surface in ventral view, but relatively smooth in basal area along penultimate margin, broad at base, narrowed apicad in about basal two-thirds at sides, slender in apical half, subparallel at sides in apical third, and slightly bilobate in apical part with rounded emargination and apices.

Male genitalia cymbiform in general appearance; ventral part of basal piece convex medio-ventrad, somewhat ovate in outline in dorsal view but subtruncate at basal margin in ventral view, elongate dorsad in apical part in profile, deeply emarginate in the middle at apical margin with each apical part narrowed to tip apico-laterally in caudal view, having a pair of longitudinal carinae covered with pubescence on cephalic surface in the elongate apical part; dorsal part of basal piece oblong, obtusely rounded at apical angles covered with pubescence, and subtruncately rounded in basal part in dorsal view, concave medio-ventrad in apical half, with a projection in the middle at apical margin, gently convex medio-dorsad and slightly narrowed basad in basal half in dorsal view, curved dorsad, and obtusely rounded at base in profile; lateral lobe nearly lanceolate in outline and somewhat arcuate mesad in dorsal view, laterally compressed and slightly attenuate around apex in profile, with a longitudinal row of spines on dorsum and an acute small projection at laterobasal part.

Length of body: 3.5–4.3 mm; width of body: 0.8–1.0 mm; length of hind tibia: 1.1–1.3 mm.

FEMALE. Similar to male, but body slightly larger and darker in coloration, particularly so on elytra sometimes having larger blackish parts than in male; vertexal marking on head somewhat larger and often extending posteriad; penultimate abdominal sternite sometimes dusky in antero-central area. Head 1.27–1.43 times as wide as pronotum; eyes smaller than in male and interocular distance 4.03–4.58 times as large as radius of eye; antennae shorter than in male, reaching about basal 4/9 of elytra, and relative lengths of antennal segments from base as follows—20.7: 12.4: 12.3: 14.0: 14.5: 14.1: 13.6: 12.5: 10.9: 9.9: 10.7. Pronotum 1.00–1.06 times as long as wide. Elytra 2.19–2.76 times as long as wide. Relative lengths of metatarsal segments from base as follows—16.5: 8.3: 6.1: 8.0: 8.2. Eighth abdominal sternite somewhat trapezoidal in outline and gently narrowed apicad, shallowly emarginate in the middle at posterior margin in ventral view, moderately convex medio-ventrad, relatively smooth and lustrous on surface. Female terminalia somewhat stout; paraproct almost divided symmetrically into two parts, each part nearly ovate in outline but not constricted basad in apical part in dorso-lateral view; coxite subcylindrical but slightly flattened dorsoventrad, weakly narrowed apicad, rounded at apex in ventral view, with a lapel at the base which is tapered and faintly warped at the mesal part.

Length of body: 3.5–5.2 mm; width of body: 0.9–1.3 mm; length of hind tibia: 1.1–1.6 mm.

Specimens examined. Japan: HONSHU [Aichi Pref.] Chita Pen., Tokoname-shi, 1 female, 11–13.v.1996 (H. Yoshitomi). [Mie Pref.] Kii-Nagashima, Takatsuka Park, 1 male and 1 female, 23.v.1972 (H. Ichihashi, MSC). [Wakayama Pref.] Kouyasan, 1 female, 17.vi.1952 (S. Gotô, NSMT). Mt. Nishi, 2 females, 3.v.2001 (H. Kojima). [Hyôgo Pref.] Mt. Myouken, 1 female, 13.vi.1997 (T. Tachi). [Shimane Pref.] (Oki Isls.: Nishinoshima) Takuhi-yama, 1 male and 4 females, 25.v.2005 (Y. Okushima, KURA); 1 male and 5 females, 26.v.2005 (Y. Okushima, KURA). (Oki Isls.: Dôgo) Fuse-mura, Uzuki, 2 males and 3 females, 20.v.2004 (T. Shimada, KURA). Fuse-mura, Minami-dani (100 m), 1 male, 18.v.2004 (T. Shimada, KURA). Saigô-chô, Tamawakasu-no-mikoto-jinja, 2 males and 3 females, 28.v.2003 (T. Shimada, KURA). Saigô-chô, Ôku, 4 males and 1 female, 16.vi.2003 (T. Shimada, KURA); 21 males and 20 females, 20.v.2003 (T. Shimada, KURA and NTC); 5 females, 13.vi.2005 (T. Shimada, KURA). [Yamaguchi Pref.] Yashiro Is., Aganoshô, 1 male and 1 female, 14.v.2002 (Y. Higashiura). Yanai-shinai, 1 female, 14.vi.1993 (N. Okimoto). Yamato, Tsukari, 1 female, 12.v.2002 (Y. Higashiura). SHIKOKU [Kagawa Pref.] Shoudo Is., Uchinomi, 1 female, 14.v.2005 (H. Fujimoto). Sakaide, Goshikidai, 1 female, 23.v.2009 (H. Fujimoto). Marugame, Honjima Is., 1 female, 6.v.2002 (H. Fujimoto). Marugame, Ushijima, 1 female, 24.iv.2004 (H. Fujimoto). Sanagi Is., 2 males, 4.v.2000 (H. Fujimoto). Nio, Takumagoe, 1 male and 1 female, 28.iv.2001 (H. Fujimoto). Mt. Kotohira, 2 males, 7.v.2000 (H. Fujimoto). [Tokushima Pref.] Ikeda-chô, Iyadani, 1 female, 8.v.2004 (H. Fujimoto). [ Kôchi Pref.] Kami City, Todorokinotaki, 1 male, 20.v.2008 (N. Takahashi). [Ehime Pref.] Omogomura, Wakayamakanmon, 1 female, 9.v.2001 (S. Yano, OMM). KYUSHU [Fukuoka Pref.] Tagawa City, 1 female, 15.v.1978 (Y. Takakura, KMNH). Yamada City, Kumagahata, 1 male, 3.v.1977 (Y. Takakura, KMNH). Genkai, Cape Kanenomisaki, 1 female, 18.v.1984 (Y. Takakura, KMNH). Mt. Inunaki, 1 male, 2.vi.1995 (N. Takahashi); 1 male, 4.v.1998 (H. Fujimoto). Mt. Tachibana, 2 males and 6 females, 18.v.1994 (N. Takahashi); 1 female, 31.v.1994 (N. Takahashi); 2 males and 4 females, 11.v.1995 (N. Takahashi); 4 males and 1 female, 16.v.1995 (N. Takahashi); 1 female, 18.v.1995 (H. Fujimoto); 1 male and 1 female, 13.v.1998 (H. Fujimoto); 2 males, 15.v.1998 (H. Fujimoto). Fukuoka City, Minami Kouen, 1 female, 17.v.1997 (H. Fujimoto). Shikanoshima, 1 male, 26.iv.1994 (H. Kojima); 3 males and 4 females, 29.iv.1994 (K. Morimoto); 2 males and 3 females, 24.v.1995 (T. Tachi); 1 male and 1 female, 6.v.1996 (K. Morimoto); 1 female, 10.v.1999 (H. Fujimoto). Fukuoka City, Atago Shrine, 1 male and 2 females, 4.v.2001 (H. Fujimoto). Motooka, 1 female, 10.vi.1996 (Y. Higashiura). Chikuzen, Sangunzan, 1 female, 10.v.1931 (K. Yasumatsu, ELKU). Chikuzen, Korasan, 1 female, 11.v.1930 (Esaki, Hori, Takeya, Hashimoto, Fujino, Yasumatsu & Choh, ELKU). Mt. Hiko, 1 female, 23.v.1994 (K. Yoshizawa); 1 female, 5.vi.1998 (H. Inoue). Mts. Hikosan, nr. Notouge (alt. 800 m), 4 females, 1.vi.2001 (H. Inoue). (Okinoshima Is.) 1 male, 20.v.1933 (Esaki & Hori, ELKU); 1 male, 27.v.1933 (Esaki & Hori, ELKU); 1 female, 20–21.v.1998 (K. Morimoto, ELKU). [Nagasaki Pref.] (Tsushima Is.) Sasuna, 1 male and 2 females, 23.v.1961 (M.-T. Chujo, ELKU). Kaijin Shrine, 2 females, 3.v.1993 (R. Noda). Kamisaka, 1 male and 8 females, 29.v.1997 (N. Takahashi). Mt. Ariake, 2 females, 28.v.1997 (N. Takahashi). Mt. Tatera, 4 males and 2 females, 29.v.1995 (N. Takahashi); 1 female, 27.v.1997 (N. Takahashi); 2 males and 11 females, 28.v.1997 (N. Takahashi). (Iki Is.) Katsumoto, 1 male, 24.iv.1999 (H.-l. Xu). (Gotô Isls.: Fukue Is.) Fukue–Kishuku, 1 female, 11.v.1994 (H. Kojima). Mt. Sasa, 1 male and 1 female, 3.v.2007 (N. Takahashi). Mt. Nanatsu, 1 male and 2 females, 2.v.2007 (N. Takahashi). [Ôita Pref.] Kamae-chô, Senzaki Park, 1 male, 17.iv.1998 (H. Kojima). Mt. Takahira, 1 male, 17.iv.1998 (H. Kojima). Kamae-chô, Ogamae–Maruichibi, 6 males and 4 females, 18.iv.1998 (H. Kojima). Kamae-chô, Nakagawara– Sunomoto, 2 males and 2 females, 18.iv.1998 (H. Kojima). [Miyazaki Pref.] Mt. Aoi, 1 female, 15.iv.1996 (H. Goto). [Kagoshima Pref.] Mt. Hoyoshi, 2 males, 4.v.1994 (R. Noda). Kôyama-chô, Hoyoshi-rindô, 2 males, 14.iv.2002 (H. Yoshitake). Kagoshima City, Shiroyama, 2 males and 1 female, 23.iv.1999 (H. Fujimoto). Kagoshima City, Minamimatsugano (350 m), 2 females, 14.v.2007 (H. Inoue). Cape Sata, 1 male, 20.iii.1994 (N. Wasano). (Koshiki Isls.: Kamikoshiki Is.) Sato, 1 female, 14–15.iv.1973 (Y. Furuki, MSC). (Koshiki Isls.: Shimokoshiki Is.) Teuchi, 3 females, 17.v.1994 (T. Ueno). Mt. Otake, 1 male, 18.v.1994 (T. Ueno); 1 male, 20.v.1994 (T. Ueno). (Yaku Is.) Miyanoura, 1 male, 17.iv.1954 (Y. Kurosawa, NSMT); 1 female, 19.iv.1954 (Y. Kurosawa, NSMT); 1 female, 23.iv.1954 (Y. Kurosawa, NSMT); 1 male, 28.iv.1954 (Y. Kurosawa, NSMT); 1 male and 1 female, 29.iv.1954 (Y. Kurosawa, NSMT); 2 females, 14.v.2006 (T. Yamauchi). Kosugi Vall., 11 males and 8 females, 6.v.1998 (N. Takahashi); 21 males and 5 females, 7.v.1998 (N. Takahashi). Kankake (in Cryptomeria japonica plantation, 220 m alt., by Malaise trap), 2 females, 31.iii–28.iv.2007 (T. Yamauchi et al.); 1 female, 1.v–5.vi.2007 (T. Yamauchi et al.). Mt. Aiko (in C. japonica plantation, 150 m alt., by Malaise trap), 1 male and 1 female, 30.iii–29.iv.2007 (T. Yamauchi et al.). Mt. Aiko (in old-growth evergreen broadleaf forests, 170 m alt., by Malaise trap), 2 females, 2.v–5.vi.2007 (T. Yamauchi et al.). Mt. Hanzan (in old-growth evergreen broadleaf forests, 250 m alt., by Malaise trap), 3 males, 2–28.iii.2007, (T. Yamauchi et al.); 2 males, 28–31.iii.2007 (T. Yamauchi et al.); 2 males and 13 females, 31.iii–28.iv.2007 (T. Yamauchi et al.); 2 females, 28.iv–1.v.2007 (T. Yamauchi et al.); 2 females, 1.v–5.vi.2007 (T. Yamauchi et al.). (Tokara Isls.: Nakanoshima Is.) 1 male and 1 female, 28.iv.1995 (N. Takahashi); 7 males and 3 females, 29.iv.1995 (N. Takahashi). Rindô Nakanoshima Line, 2 males and 7 females, 18.iv.1997 (N. Takahashi). Funakura–nr. Oike, 3 males and 6 females, 19.iv.1997 (N. Takahashi). Mt. Ontake, 5 males and 4 females, 20.iv.1997 (N. Takahashi).

Type locality. Japonia [according to the date written on the undersurface of card-board glued with the type material deposited in the Natural History Museum, London, and Kusama (1971), the type locality of this species may probably be in Kumamoto City of Kumamoto Prefecture, Central Kyushu, Japan].

Distribution. Japan: Honshu, Oki Isls., Shikoku, Kyushu, Tsushima Is., Iki Is., Gotô Isls., Koshiki Isls.*, Yaku Is.*, and Nakanoshima Is.* (Tokara Isls.). An asterisk after each locality name indicates this species is new to the location.

Infraspecific variation. Infraspecific variations are recognized in some parts and some morphological characters are not distinctly stable in particular areas. The vertexal marking on the head is variable in shape and size, rarely reduced into an almost smaller transverse elliptical shape and extended over a large part posterior to the vertex on the dorsum. The pronotum is also slightly variable in appearance, particularly at the margins, as well as the degree of emargination at the apices of the male 9th abdominal sternite and the ventral part of basal piece of the male genitalia. Most of the elytron is sometimes dusky except for the yellowish apical spot, although small yellowish parts remain only at the basal area and along the suture and ventral margin of the epipleuron. Lateral lobe of the male genitalia is sometimes faintly denticulate at the apical margin, which is slender in the apical part in the material collected from Nakanoshima Island. Spines, present on the dorsum of lateral lobe of the male genitalia, are sometimes intermittently placed in a row, particularly in the basal half of the dorsum where they were generally shorter than those in the apical region and some were often obsolete. The posterior margin of the last abdominal sternite and coxites of the terminalia in female varies slightly in appearance. Further investigations are needed to clarify infraspecific variations in this species, particularly based on material being unavailable within its distributional range of this study.

Remarks. This species is closely related to the following new species from the middle Ryukyus, but is distinguishable from the latter by the almost simple apex of the lateral lobe and basal part of the dorsal part of basal piece in the male genitalia, and the subcylindrical coxites of the female terminalia.

Figures

FIGURES 1 – 8. Habitus of Malthinus spp. 1 – 4, Malthinus mucoreus (Kiesenwetter) (1, male from Kagoshima Pref.; 2, female from Tsushima Is.; 3, type material; 4, type labels; 3 – 4, photos courtesy by Y. Okushima, taken at the Natural History Museum, London); 5 – 6, M. serrulatus N. Takahashi, sp. nov. (5, holotype; 6, female); 7 – 8, M. orbiculatus N. Takahashi, sp. nov. (7, holotype; 8, female).

FIGURES 9 – 12. Apical portions of male 9 th abdominal sternites of Malthinus mucoreus, ventral view. 9, from Tsushima Is.; 10, from Fukuoka Pref.; 11, from Shimokoshiki Is.; 12, from Nakanoshima Is. Scales: 0.25 mm.

FIGURES 13 – 16. Male genitalia of Malthinus mucoreus. 13 – 14, apical portion of ventral part of basal piece, caudal view (13, from Fukuoka Pref.; 14, from Shimokoshiki Is.); 15, dorsal view; 16, lateral view. Scales: 0.25 mm for FIGS. 13 – 14; 0.5 mm for FIGS. 15 – 16.

FIGURES 17 – 21. Malthinus mucoreus, female. 17, blackish markings on head and pronotum, an instance; 18 – 21, pronota in outline, dorsal view (18, from Tsushima Is.; 19, from Fukuoka Pref.; 20, from Shimokoshiki Is.; 21, from Nakanoshima Is.). Scales: 1.0 mm for FIG. 17; 0.5 mm for FIGS. 18 – 21.

FIGURES 22 – 27. Malthinus mucoreus, female. 22 – 24, apical margins of 8 th abdominal sternites in outline, ventral view; 25 – 27, terminalia, ventral view (22, 25, from Tsushima Is.; 23, 26, from Fukuoka Pref.; 24, 27, from Nakanoshima Is.). Scales: 0.25 mm.