Mentophilonthus dilutior ( Bernhauer, 1928 )

Hromádka, Lubomír, 2009, Revision of the Afrotropical species of the genus Mentophilonthus (Coleoptera: Staphylinidae: Philonthina), Acta Entomologica Musei Nationalis Pragae (suppl.) 49 (1), pp. 119-160 : 131-132

Mentophilonthus dilutior ( Bernhauer, 1928)

( Figs. 34–40 )

Philonthus (Philonthus) dilutior Bernhauer, 1928: 113 .

Mentophilonthus dilutior: LEVASSEUR, 1966: 208 , 211.

Type locality. Democratic Republic of the Congo, Mongende.

Type material. HOLOTYPE: ♁, ‘ Congo Belge, Mongende , 19.iv.1921, Schouteden, Chicago NHMus. M. Bernhauer, collection, // Type Philonthus dilutior Bernhauer det. [yellow oblong label, handwritten]’ ( FMNH).

Redescription. Body length: 7.1 mm (with stretched abdomen), length of fore body (to end of elytra) 4.2 mm.

Colouration. Head black, antennal sockets and clypeus along anterior margin very narrowly brown-yellow, pronotum and abdomen black-brown, elytra brown-reddish palpi brown-yellow, antennomeres 1–2 yellow-brown, remaining antennomeres blackish, legs yellow-brown, tibiae and tarsi infuscate.

Head rounded, hardly longer than wide (ratio 22: 20.5). Eyes slightly longer than temples (ratio 11: 9). Anterior margin of each eye with two coarse punctures. Dorsal surface with fine and dense microsculpture consisting of transverse and oblique waves, in places intermixed with numerous microscopic dots.

Antennae reaching posterior margin of pronotum when reclined. Antennomere 2 shorter than antennomere 3. Relative lengths of antennomeres: 1 = 9.5; 2 = 4; 3 = 5; 4–9 = 3.5; 10 = 3; 11 = 4.

Pronotum somewhat longer than wide (ratio 34: 32), hardly narrowed anteriad. Posterior angles entirely rounded. Each dorsal row with two punctures; each sublateral row with one puncture. Microsculpture similar to that on head.

Scutellum exceedingly finely and sparsely punctate, punctures somewhat smaller than eye-facets, separated by 1–1.5 puncture diameters in transverse direction. Microsculpture much finer than that on head and pronotum.

Elytra combined wider than long (ratio 43: 37), distinctly widened posteriad. Punctation rather coarse and dense, punctures as large as eye-facets, transverse interspaces between punctures equal to diameter of punctures. Longitudinal row of three larger punctures situated at about midwidth of each elytron. Surface without microsculpture; setation greyish.

Legs. Metatibia longer than metatarsus (ratio 24: 22). Metatarsomere 1 as long as metatarsomeres 2–3 combined. Relative lengths of metatarsomeres: 1 = 8; 2–3 = 4; 4 = 3; 5 = 6.

Abdomen with first four visible tergites with two basal lines, elevated area between basal lines very finely and very sparsely punctate, punctation of all tergites similar to that on elytra; setation of the same colour as that on elytra.

Male. Protarsomeres 1–3 markedly dilated and subbilobed, densely covered with modified pale setae ventrally, protarsomere 4 only slightly narrower than preceding ones. Sternite VIII ( Fig. 38 ), sternite IX ( Fig. 39 ), aedeagus ( Figs. 34–37 ).

Female. Protarsomeres 1–3 less dilated than those of male, protarsomere 4 small, only protarsomeres 1–3 bearing modified pale setae ventrally. Tergite X ( Fig. 39 ), gonocoxite of female genital segment ( Fig. 40 ).

Differential diagnosis. Menthophilonthus dilutior differs from M. mongendensis by paler antennomeres 1–2, shorter antennomeres 1–11 and sparser punctation of the elytra. It differs from M. ochrigonalis by a wider head and denser punctation of the abdomen, and from M. odzalaensis by a denser punctation of the elytra. The species may be distinguished from all other species of Mentophilonthus by the shape of the aedeagus.

Bionomics. Unknown.

Distribution. Democratic Republic of the Congo.

Figures

Figs. 24–38. 24–28 – Mentophilonthus descarpentriesi Levasseur, 1965: 24–27 – aedeagus (24 – ventral view, 25 – lateral view, 26 - ventral view, without paramere, 27 – underside of paramere, with sensory peg setae); 28 – male sternite IX, ventral view. 29–33 – Mentophilonthus dilucidus (Tottenham, 1962): 29–33 – aedeagus (29 – ventral view, 30 – lateral view, 31 – ventral view, without paramere, 32 – underside of paramere, with sensory peg setae, 33 – lateral view without paramere). 34–38 – Mentophilonthus dilutior (Bernhauer, 1928): 34–37 – aedeagus (34 – ventral view, 35 – lateral view, 36 – ventral view, without paramere, 37 – underside of paramere with sensory peg setae); 38 – apical portion of male sternite VIII, ventral view.

Figs. 39–48. 39–40 – Mentophilonthus dilutior (Bernhauer, 1928): 39 – female tergite X, dorsal view; 40 – gonocoxites of female genital segment. 41–42 – Mentophilonthus equus sp. nov.: 41 – female tergite X, dorsal view; 42 – gonocoxites of female genital segment. 43–48 – Mentophilonthus hystrix sp. nov.: 43–45 aedeagus (43 – ventral view, 44 – lateral view, 45 – underside of paramere with sensory peg setae); 46 – apical portion of male sternite VIII, ventral view; 47 – male sternite IX, ventral view; 48 – female tergite X, dorsal view.