Merizomena (Dichromenta), Muilwijk & Felix & Anichtchenko, 2022

Muilwijk, Jan, Felix, Ron & Anichtchenko, Alexander, 2022, A taxonomic revision of the genus Merizomena Chaudoir, 1873 (Coleoptera: Carabidae: Lebiini), Baltic Journal of Coleopterology 22 (1), pp. 1-54 : 15-16

Subgenus Dichromenta subg. n.

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Type species Merizomena (Dichromenta) castanea ( Klug, 1832)

Description. Small to medium sized Lebiini (BL: 5.5–9 mm); body moderately flat. Head and pronotum monochromous yellowish to reddish, elytra

Muilwijk J., Felix R., Anichtchenko A.

bicolored: base yellowish­red, distal part dark, without metallic lustre, ventral side yellowish, apex more or less brownish; appendages yellowish.

Head. Elongate, tempora with short setae. Frons and vertex with punctures and pubescence. Supraorbital furrow sharp. Maxillary palpi with basal segment widened apically, not thickened. Ultimate palpomere fusiform, slightly longer than penultimate one, with a few small hairs. Penultimate labial palpomere with two long setae on anterior margin.Apical segment of labial palpi securiform, with stout hairs. Gula convex. Mentum punctate at lateral sides, with two setae at anterior margin. Mentum tooth long, slightly shorter than lateral lobes, broadly rounded at apex. Genae finely punctate, with fine erect hairs. Antennae slender, exceeding elytral base approximately by two antennomeres.

Thorax. Pronotum cordate slightly transverse; covered with punctures and pubescence; lateral gutter wide. Anterior margin subrectilinear. Both anterior and posterior margin with a fringe of fine hairs. Anterior angles broadly rounded. Base without margin in middle, lateral margin with hairs. Without basal transverse impression. Lateral sides with one seta in basal angle, and one (two) approximately at widest point. Prosternal process finely marginated, with a few long setae. Metacoxae with two long setae. Prosternum, proepisterna, meso­ and mesasternum and meso­ and metepisterna with scattered punctures and hairs, denser on proepisterna and meso­ and metepisterna. Metepisterna long. Elytral apical border with a few fine punctures.

Abdomen. Elytra relative long (approximately 3.5 times longer than the pronotum) and wide (two times wider than the pronotum), moderately convex. Basal border complete. Sutural apical angle nearly at right angle, with or without a small denticle. Striae slightly embedded; striae 7 and 8 curve to sutural apex. Umbilicate series continuous, consisting of 15–18 setiferous pores; one preapical pore located at apex of stria 3. Ventrites pubescent, denser on anal ventrite, anal ventrite with 5 pairs of setae along apical margin.

Legs. More slender than in the nominate subgenus, especially metatibiae and tarsi. Dorsal surface of tarsi provided with sparse long hairs.

Median lobe. Long, endophallus with 1 or 2 copulatory pieces.

Female genitalia. Gonocoxite 1 without setae, gonocoxite 2 cone shaped with setae in the apical quarter. Laterotergite IX curved; wider and less strongly chitinized as in species from the nominate subgenus. The spermatheca is divided in a pedicel ending in the bursa copulatrix and beginning at the point of the short branch of the spermatheca in which the duct of the spermathecal gland flows and a thicker distal part. The duct of spermathecal gland is very long and thin. The spermatheca is covered with dense villi in the middle part.

Comparative notes. Species of this subgenus differ from species of the nominate subgenus by the elytral base completely marginated, the more elongated and flat body, the slenderer appendages, and yellowish colour of head and ventral side.

Etymology. The name of the subgenus is derived from the bicolour dorsum.