Platybolium watanai, Maruyama & Sasitorn & Ando, 2023

Maruyama, Munetoshi, Sasitorn, Hasin & Ando, Kiyoshi, 2023, A description of the second species of the genus Platybolium Blair, 1938 (Coleoptera: Tenebrionidae) collected from a nest of Pheidole singaporensis Özdikmen, 2010 (Hymenoptera: Formicidae) in Thailand, Zootaxa 5256 (3), pp. 289-294 : 290-292

Platybolium watanai sp. nov.

( Figs. 1–9 )

Type series. Holotype: ♁, Thai: Chiang Mai, Doi Suthep National Park, National Park Lodging , 18˚48’21.74”N, 98˚55’5.46”E, 1050 m, 22–23.XII.2015, Maruyama-M. leg. ( KUM) . Paratypes: 3 ♁♁, 3 ♀♀, same data as for the holotype (2 in KUM, 2 in DNP, 2 in CKA) .

Description. Oblong, subparallel-sided, weakly convex, covered with fine microsculpture, subshiny. Colour dark reddish brown, darkened in part; dorsal side blackish brown except marginal portions. Body length: 4.7–5.4 mm in male (n = 4; average 5.1 mm), 4.7–5.7 mm in female (n = 3; average 5.3 mm).

Male. Head transversely rhombic, with rounded anterior margin though very slightly sinuous in middle; punctures dense, larger and clear on frons to vertex, smaller and obscure on clypeus and genae; clypeus and frons weakly convex, individually; genae flattened, roundly produced laterad; frons sloping laterally, overhanging like eaves on inner margins of eyes, space between eyes 4.71–5.33 times as wide as an eye (n = 4; average 5.01 times); eyes coarsely facetted, strongly invaded by genae.Antennae short, reaching apical two-fifths of pronotum, compactly articulate, gradually dilated towards apical antennomeres, especially strongly so in distal five antennomeres; 3rd antennomere distinctly shorter than its apical width (5:7). Ultimate maxillary palpomeres obconical. Mentum obtrapezoidal ( Fig. 4 ), slightly wider than long (19:17), weakly convex in middle and depressed laterally, coarsely and irregularly punctate.

Pronotum transversely trapezoidal, somewhat reflexed at sides, widest at basal third and nearly as wide as elytra, 1.96–2.07 times as wide as long (n = 4; average 2.02 times); disc gently convex, weakly sloping laterally, broadly depressed along lateral margins; punctures coarse and very dense, nearly as large as and/or slightly larger than on frons, constantly becoming sparser and smaller in lateral depressed areas; anterior margin moderately emarginate, straight in median three-fifths, very finely beaded; anterior corners obtusely rounded, slightly produced; lateral margins gently rounded, finely beaded; posterior corners nearly rectangular, rounded at the tip; basal margin weakly bisinuate, thinly beaded. Scutellum large, obtriangular, with dense punctures.

Elytra elongate, subparallel-sided, gently convex, widest at middle or behind middle, 1.41–1.46 times as long as wide (n = 4; average 1.43 times), finely beaded at sides and strongly depressed along sides in about outer half of 9th intervals; with rows of punctures instead of striae; punctures in rows dense and irregular, larger than on pronotum, distinct even in apical declivity; intervals weakly to moderately convex, densely with microscopic piligerous punctures, weakly carinate on mid of 8th one, the carina terminated before apical declivity of elytron; epipleura flat or weakly depressed, gently and finely punctate, reaching apex of 5th abdominal ventrite.

Prothoracic hypomera distinctly depressed, densely punctate, with irregular rugosities. Prosternum moderately convex towards middle, coarsely and densely punctate, hardly beaded at apex; prosternal process guttiform ( Fig. 5 ), incurved behind coxae, irregularly punctate. Mesoventrite with V-shaped posterior ridge coarsely punctate, without anterior angle in lateral view. Metaventrite moderately convex, with punctures moderately dense and piligerous. Abdomen weakly convex, densely covered with piligerous punctures; 8th sternite weakly emarginate at apex and slightly depressed in middle ( Fig. 6 ). Defensive glands distinctly and densely annulate as in Fig. 9 .

Aedeagus robust ( Figs. 7, 8 ), 0.28–0.30 times as long as elytra (n = 4; average 0.29 times); basale weakly convergent towards base, scarcely emarginate or notched at apex, 2.22–2.89 times as long as apicale (n = 4; average 2.59 times); apicale short, styliform, microscopically punctate, with sides emarginate in apical third.

Legs short and robust. Femora fusiform, densely with setiferous punctures; anterior margins of profemora and posterior margins of meso- and metafemora distinctly ancipital. Tibiae short; outer margins of protibiae densely and minutely denticulate, those of mesotibiae sparsely so; inner margins of protibiae with irregular and minute tubercles. Tarsi simple, compactly articulate.

Female. Space between eyes 5.33–5.71 times as wide as an eye (n = 3; average 5.46 times); pronotum 1.93–2.00 times as wide as long (n = 3; average 1.96 times); elytra widest at middle or basal third, 1.48–1.50 times as long as wide (n = 3; average 1.49 times); ovipositor and tract are shown in Fig. 10 , gonostyle lateral, coxite lobes not confused with each other, coxite lobe 1 baculus and paraproct baculus well sclerotized, vagina without window, spermathecal gland short and apical, accessory gland with an arcuate terminal capsule.

Etymology. Patronym. Named in recognition of Dr. Watana Sakchoowong, who always supports MM in his collecting trips and obtaining research permits in Thailand.

Differential diagnosis. The new species is similar to Platybolium alvearium Blair, 1938 (type of the genus), but is readily separable from the latter by having the wider and flatter lateral margins of the pronotum and elytra, and by the more shining body surface. They are also distinguished in the following key.

Figures

FIGURES 1–3. Platybolium watanai sp. nov.: 1. holotype, dorsal view; 2. ditto, dorso-lateral view; 3. paratype at the host ant nest entrance. Scales: 1.0 mm.

FIGURES 4–10. Platybolium watanai sp. nov.: 4. mentum; 5. prosternal process; 6. eighth sternite; 7, 8. aedeagus (right: lateral view; left: dorsal view); 9. defensive glands; 10. female cuticular structure in ventral view. Scales: 0.1 mm for 4–8; 0.5 mm for 9–10.