Meroloba siberutana, Jákl, 2011

Jákl, Stanislav, 2011, Description of seven new taxa of Cetoniinae from Indonesia (Coleoptera: Scarabaeidae), Acta Entomologica Musei Nationalis Pragae 51 (2), pp. 535-550 : 542-547

Meroloba siberutana sp. nov.

( Figs. 5a–c )

Type locality. Indonesia, West Sumatra province, Mentawai Archipelago, northern part of Siberut Island, environs of Bojakan village, 50–200 m a.s.l.

Type material. HOLOTYPE: J ( NMPC): ‘ Indonesia, Mentawai Isls., SIBERUT ISL., north, 50 – 200 m, BOJAKAN VILL. ENV., 5. 2004, St. Jakl lgt’ . PARATYPES: 10 JJ (nos. 1–10), 10 ♀♀ (nos. 11–20) and 100 unsexed specimes (nos. 21–120), same label data as holotype ( SJPC, two paratypes each at BMNH, MNHN, NMPC).

Description. Holotype length 17.9 mm, maximum humeral width 8.2 mm. Velvety black with golden-yellow tomentum.

Head. Black, covered with basal tomentum. Laterally with two stripes of golden-yellow tomentum not reaching apex of clypeus. Punctation simple, denser on clypeus. Widest at three-fourths of length. Apical margin of clypeus deeply incised. Antennae simple, dark brown, with yellowish setosity.

Pronotum. Velvety black, impunctate. From midlength sharply narrowing to apex. Decorated with three longitudinal stripes of golden-yellow tomentum running from anterior margin to base. Two stripes run laterally, but leaving narrow lateral margin black; one stripe runs medially to base of pronotal lobe. Anterolateral margins with very low, obtuse border, rest of margins unbordered. Lateral margins with shallow emargination in front of posterolateral margins. Yellowish setae very short, but present throughout length.

Scutellum. Triangular, entirely under pronotal lobe and completely covered with golden tomentum.

Elytra. Velvety black, sharply narrowing to apex. Impunctate, apex wrinkled. Each elytron decorated with three stripes of golden-yellow tomentum running from base to apex. Two of them adjoin pronotal stripes, third (lateral) runs along epipleura. Medial stripe runs along sutural ridge and reaches apex of elytron, lateral stripes stop at level of apical calli and join each other. Lateral ridge obtuse, except apically, where it bears short costae in front of apical calli. Humeral calli indistinct. Sutural ridge flat, slightly elevated in posterior quarter, its termination obtuse, not protruding over apex of elytra.

Pygidium. Small, semicircular, entirely covered by elytra. Completely covered with golden tomentum.

Venter. Black, velvety tomentum absent, surface shining. Medial furrow not developed. Each ventrite finely punctured. Each puncture bears short yellow setae. Each ventrite laterally with golden tomentum, widest on first ventrite, narrowest on apical ventrite. Metasternum except for mesometasternal part completely covered with yellow tomentum. Meso-metasternal area striolated, midline furrow developed. Meso-metasternal process black, slightly protruding in front and downwards, terminating in keel-shaped declivity. Prosternum and mentum covered with tomentum and longer yellowish setation.

Legs. Black to dark brown, moderately long. Femora and tibiae with small patches of golden tomentum. Protibiae tridentate, mesotibiae with small carina at midlength. Knees and coxae reddish brown.

Male genitalia. Similar to other representatives of genus ( Figs. 5d–e ).

Variability. Body length 16.5–18.5 mm. All males available for study almost identical.

Sexual dimorphism. Female body length 16.2–18.4 mm. Both sexes very similar except for protibiae (slightly more robust) and abdomen (more arched).

Differential diagnosis. Regionally closely allied species is Meroloba suturalis Snellen van Vollenhoven, 1858 , from which differs mainly by the pattern and colour of the elytral tomentum stripes. Each elytron of the newly desribed species is decorated with three longitudinal golden-yellow tomentum stripes. In M. suturalis the tomentum is silky beige and its two outer stripes are reduced and irregularly cover only the areas of striolate lines. The genitalia of the new species have the termination of the paramere tip sharply triangular, whereas in M. suturalis it is elongated. Similar is also M. quadrilineata Nagai, 1984 from Palawan Island, from which the newly described species differs in four respects: 1) elytral costae very short, running at apical third of elytra (costae run from subhumeral level to apex of elytra in M. quadrilineata ); 2) lateral part of elytra (between lateral ridge and epipleura) steeply gradual, not vertical as in M. quadrilineata ; 3) epipleura black (covered with golden tomentum and adjoining the sutural tomentum stripe in M. quadrilineata ); 4) body length of newly described species 16.2–18.5 mm, of M. quadrilineata 19.1–22.2 mm.

Etymology. Named after Siberut Island.

Distribution. So far known only from the type locality on Siberut Island, Mentawai Archipelago, Indonesia.

Figures

Fig. 5. – Meroloba siberutana sp. nov. a – habitus dorsally; b – habitus laterally; c – habitus ventrally; d – aedeagus apically. Not in scale.