Stereodermus micropterus Mantilleri

Mantilleri, Antoine, Bartolozzi, Luca & Sforzi, Alessandra, 2017, Brentidae of Peru (Coleoptera: Curculionoidea), Zootaxa 4221 (1) : -

Stereodermus micropterus Mantilleri , sp. nov.

( Figs. 1–8 )

Type material. Holotype: ♀, Peru, Madre de Dios, Pantiacolla lodge, Monk Saki trail, Alto Madre de Dios River , 400 m, 12°39'22''S 71°13'55''W, 25.X.2000, R. Brooks, under bark, prép. micro. n°AM-KUNHM 0 0 0 0 1 ( KUNHM) .

Paratype: 1 ♀, idem holotype (KUNHM).

Description of female. Length from apex of rostrum to apex of elytra: 4.5–5.3 mm; length from apex of pronotum to apex of elytra: 3.5–4.1 mm; width across humeral calli: 0.8–1.0 mm. Habitus: Fig. 1 .

Dark brown-red, legs lighter.

Head ( Fig. 2 ) much broader than long, not punctate, more or less concave or notched at base, with longitudinal groove. Temples almost indistinct, glabrous. Metarostrum and mesorostrum grooved. Sides of metarostrum ( Fig. 3 ) with 2–3 weak sensorial pores. Prorostrum very elongate but slightly shorter than head, metarostrum and mesorostrum together. Venter of head and metarostrum glabrous, base with shallow thin groove. Venter of mesorostrum glabrous, with two paramedian grooves. Antennal scape almost as broad as long, hardly longer than antennomeres 2–3 together ( Fig. 4 ); articles 2–8 very short, much broader than long, with row of short thick setae; articles 9–10 cylindrical, broader than long; article 11 shorter than articles 9–10 together.

Pronotum not punctate, microreticulate, glabrous, with longitudinal median groove deeper at base, connected to collar constriction. Prosternum depressed behind collar constriction. Prosternellum distinct. Metasternum not grooved, with very shallow punctures on sides. Elytra fused together (but suture still distinct), glabrous, shiny, base straight with humeral calli not strongly marked; interstriae 3–10 quite deep, striae 5–8 with large punctures. Metanotum ( Fig. 6 ) almost completely membranous; hind wings ( Fig. 6 ) vestigial. Femora unarmed, glabrous except few short thick setae at base of metafemora. First metatarsal segment shorter than segments 2–3 together.

Sternites III–IV ( Fig. 5 ) almost glabrous, hardly punctate, with longitudinal depression. Sternites V–VI almost glabrous with very shallow punctures. Sternite VII with few setae and large shallow punctures, weakly depressed on each sides at apex. Tergites II–V membranous, VI weakly sclerotized ( Fig. 6 ). Tergite VIII ( Fig. 7 ) of peculiar shape, without apical teeth but with deep median notch. Coxites and styli: Fig. 8 . Spermatheca ( Fig. 8 ) sickleshaped, without basal bulge.

Etymology. The specific epithet derives from the strongly reduced hind wings of the new species.

Remarks. Stereodermus micropterus sp. nov. is the second known species of brentid with reduced hind wings in the Neotropical region. Stereodermus effrenatus (Kleine, 1927) , from Brazil, originally described in the monotypic genus Stereoderminus Kleine, 1927, is also supposed to be micropterous or apterous ( Mantilleri, 2005). But because of poor conservation of the sole known specimen (internal part of thorax and abdomen were missing), apterism was not proved but only deduced from the strong reduction of the humeral calli. Stereodermus effrenatus is very similar to the new species described here, with elongate prorostrum, head with reduced temples, antennal segments broader than long, elytra with reduced humeral calli; thus, this hypothesis of apterism is now better supported as a second species with reduced hind wings was discovered. Stereodermus micropterus sp. nov. may be differentiated from S. effrenatus by the head and pronotum longitudinally grooved, and humeral calli less reduced.

Worldwide, few brentids are known to be apterous. Except for these two species of the genus Stereodermus , only Howeius micropterus Mantilleri, 2011 (Cyphagoginae Hoplopisthiini) from Lord Howe Island, 600 km E of Australia, shows vestigial hind wings (also associated with reduction of sclerotisation of metanotum), probably in relation to insularity. But the two species of Stereodermus here cited, closely allied, do not live on islands or on high mountains: S. effrenatus was collected in Brazil (without more exact locality) and S. micropterus sp. nov. in Peru at 400 m elevation. A peculiar biology among other Stereodermini must probably be considered.

Figures

FIGURES 1 – 18. Stereodermus spp. 1 – 8, S. micropterus Mantilleri, sp. nov., ♀: 1, paratype, habitus; 2, head, dorsal view; 3, head, lateral view; 4, left antenna; 5, abdomen; 6, abdominal tergum (mn, metanotum; hw, hind wing; TII, tergite II; TVI, tergite VI; TVII, tergite VII); 7, tergite VIII; 8, coxites and spermatheca. 9 – 18, S. platycornis Mantilleri, sp. nov.: 9, ♀ paratype, habitus; 10, head and prothorax, dorsal view; 11, head, lateral view; 12, right antenna; 13, ♂, abdomen; 14, ♀, sternite VII; 15, ♂, sternites VIII – IX; 16, tegmen; 17, penis; 18, spermatheca.