Madrasostes nomurai Ballerio & Maruyama, 2025

Ballerio, Alberto & Maruyama, Munetoshi, 2025, Review of Madrasostes Paulian, 1975 (Coleoptera: Hybosoridae: Ceratocanthinae) from Vietnam, with remarks on its generic limits, Zootaxa 5661 (3), pp. 420-430 : 425-427

Madrasostes nomurai Ballerio & Maruyama sp. nov.

( Figs. 3 ; 4A )

Type material. Holotypus, ♂ (deposited in NSMT): Cuc Phuong alt. 450m Ninh Binh Pr. / [N. Vietnam] 11.X.1995 S. Nomura leg. / Madrasostes nomurai n. sp. det. A. Ballerio & M. Maruyama 2024. Paratypi: 3 ♂♂ (1 in NSMT, 1 in KUM and 1 in ABCB): Cuc Phuong (170m) Ninh Binh Pr. [N. Vietnam] / 1.VI.1998 S. Nomura leg. ; 1 ♂ (NSMT): Cuc Phuong 320m alt. Ninh Binh Pr. / [N. Vietnam] 2.VI.1998 S. Nomura leg.

Description. Size: HL = 0.92 mm; HW = 1.11 mm; PL = 1.22 mm; PW = 2.22 mm; EL = 2.22 mm; EW = 2.11 mm. Small-sized Madrasostes . Flightless. Body strongly convex. Brown, with green metallic sheen on tubercles and carinae, dorsum glabrous (50×), underside, tarsi and antennae dark reddish-brown with setation yellowish-brown.

Head: W/L ratio = 1.35; subpentagonal, clypeal apex obtuse, apical projection very weak and sexually dimorphic, sides almost rectilinear; genal canthus small, not reaching occipital area with a very narrow and short dorsal ocular area, ventral ocular area small, transverse and narrow, genae acute, not protruding outwards, genal suture indistinct; head dorsal surface covered by large and impressed transverse comma shaped punctures, all them centripetally oriented, vertex with dense large simple punctures. Frons with a small weakly raised tubercle. Pronotum: subrectangular (dorsal view) (W/L ratio = 1.62), convex and unevenly sculptured, fore angles with a deep sinuation at each side; pronotal basal carina weakly bilobate, raised anterior carina without any visible lobation and about as wide as head, disc of pronotum with two pairs of longitudinal large weakly raised tubercles, sides of pronotum with two parallel transverse short weakly raised irregular carinae and a tubercle, pronotal punctation uniformly covering pronotal surface, consisting of a mixture of dense (interpunctural distance inferior than punctural diameter: punctures almost touching each other) large ocellate punctures and large horseshoe-shaped punctures almost rounded, punctures deep and irregular, giving a coarse appearance. Each puncture encasing another smaller horseshoe-shaped puncture. Scutellum : surface covered by dense short transverse comma-shaped punctures. Elytra : slightly longer than wide (W/L ratio = 0.96), subovoidal (dorsal view), strongly convex; humeral callus indistinct; elytral surface, besides carinae, uniformly covered by elongate large horseshoe-shaped punctures encasing another smaller, often irregularly shaped, elongate horseshoe-shaped puncture, larger punctation mixed, especially at sides of carinae, with fine simple punctures; inferior sutural stria deep and complete, striated articular area hardly visible in lateral view, relatively narrow and short; marginal area medium-sized; elytral articular process developed, smooth and shiny, with a deep line bordering scutellar sides. Elytral sculpturing as follows: dorsal area of elytra with three longitudinal sharp raised carinae spaced out by a distance about 1/3 of each elytron width, the first one marking the suture, starting at a distance from the apex of scutellum about 1/5 of the length of elytral suture and reaching elytral apex, the second carina starting at humeral area and interrupted at elytral apical third, the third starting at the same level of the first and ending at the interruption of the second, at sides there are two more carinae, one longitudinal short found at about the border between medial and distal third, the fifth carina finally starts at humeral angles and reaches apically the third carina, the fifth carina has two interruptions, which in dorsal view give a sinuate shape to the carina. Wings: flightless. Sexual dimorphism : males have the inner apical spur hooked (bent inwards at a right angle and pointed). Male genitalia: aedeagus (L = 0.8 mm) with parameres distally narrowed, bent inward and sharp in both lateral and dorsal view as in Fig. 3F , spiculum gastrale (L = 0.7 mm) elongate, having the shape of an isosceles triangle as in Fig. 4A .

Diagnosis. Madrasostes nomurai sp. nov. can be differentiated from all other species of Madrasostes by the following combination of characters: a) small size, b) genal canthus short, not reaching occipital area, with dorsal ocular area small and narrow, c) head with weakly serrate clypeal margin and with large impressed punctation, d) pronotal punctation coarse made of large ocellate or horseshoe-shaped punctures, e) pronotal anterior carina raised and without any visible lobation, f) pronotal basal carina bilobate, g) pronotal disc with carinae and/or tubercles, h) elytra dorsally with three complete longitudinal sharp carinae plus at sides one short longitudinal carina and one longitudinal carina interrupted at least twice, i) elytral punctation between carinae made of elongate large horseshoe-shaped punctures encasing another smaller horseshoe-shaped puncture, larger punctation mixed, especially at sides of carinae, with fine simple punctures, j) flightless, k) aedeagus with short apically narrowed and bent inwards sharp parameres (in lateral and dorsal view) as in Fig. 3F, l ) spiculum gastrale triangular and elongate as in Fig. 4A . The species more similar to it is M. bartolozzii , with which it shares the same elytral sculpturing made of longitudinal carinae and the same major pronotal sculpturing made of large tubercles or tubercle-like carinae, the main differences between the two species are: the clypeal serration, much stronger in M. bartolozzii , b) the pronotal punctation, which in M. bartolozzii is uniformly very fine and simple, c) the shape of parameres (in lateral view), which in M. bartolozzii are more enlarged and curved apically, and d) the shape of spiculum gastrale, which in M. bartolozzii has a distinct basal triangle with a long manubrium, whereas in M. nomurai sp. nov. the spiculum has the shape of an isoceles triangle. Both M. nomurai sp. nov. and M. bartolozzii are the only known Madrasostes to have such an elytral sculpturing, made of three strongly raised dorsal longitudinal carinae plus other two lateral ones (a character otherwise commonly found in the genus Besuchetostes Paulian, 1972 , however both species differ from Besuchetostes because of the presence of a basal pore on mandibles, a character typical of the Perignamptus generic-group, as defined by Ballerio (2009). Besuchetostes and Madrasostes also differ because of some features of the head, which will be discussed in another paper the first author has in preparation).

Etymology. Noun in the genitive case. Named after its collector, Shûhei Nomura (NSMT).

Distribution and habitat. Known only from the type locality. The area falls within the Northern Indochina Subtropical Forests ecoregion ( Wikramanayake et al. 2002).

Figures

FIGURE 3. Madrasostes nomurai Ballerio & Maruyama sp. nov. A. Distended adult in dorsal view. B. Rolled-up adult in ventral view (protibiae missing). C. Rolled-up adult in dorsal view. D. Rolled-up adult in lateral view (protibiae missing). E. Rolled-up adult: view of pronotum. F. Aedeagus in lateral, dorsal and ventral views.

FIGURE 4. Spicula gastrales of A. Madrasostes nomurai Ballerio & Maruyama sp. nov., B. Madrasostes bartolozzii Ballerio, 2013 and C. Madrasostes deharvengi Gao, 2009.