Ytu coeus, Sampaio & Ferreira-Jr, 2018

Sampaio, Brunno Henrique Lanzellotti & Ferreira-Jr, Nelson, 2018, Five new species of Ytu Reichardt (Coleoptera: Myxophaga: Torridincolidae) and new records from Brazil, Zootaxa 4402 (3), pp. 508-524 : 519-521

Ytu coeus sp. nov.

( Fig. 5 )

Diagnosis. Lateral margins of pronotum convex, abruptly curving inward on anterior fifth; the anterior third of pronotum with two pairs of shallow impressions, one medial and other sublateral; posterior half of pronotum with two pairs of shallow impressions, one near posterolateral angles and the other sublateral. Elytral formula 8d + 2a(IVa,VIa) + 1sl / 0d + 0sl; elytral intervals feebly raised; surface of striae and intervals with iridescent scales. Male genitalia with long parameres and phallus curved from basis to apex in laterally; apex digitiform bearing a pair of setae on dorsally.

Description: Holotype. Antennae black; dorsal surface black and shiny ( Fig. 5a ); ventrally dark brown ( Fig. 5b ); legs darker than ventral surface. Measurements: total length: 1.76 mm; maximum head width: 0.32 mm; pronotal length: 0.33 mm; maximum pronotal width: 0.55 mm; elytral length: 1.12 mm; maximum elytral width: 0.41 mm.

Labrum ( Fig. 5c ) with arcuate anterior margin bearing some denticles; medial region of anterior margin with a small process; anterolateral angles bearing claviform setae; lateral margin slightly arcuate; labrum surface pubescent on anterior two thirds. Anterior margin of clypeus ( Fig. 5d ) feebly arcuate; anterolateral angles oblique with a pair of setae each. Head surface with iridescent microscales; supra-orbital carina extending from clypeus to eyes, fading after reaching eyes; medial side of carinae depressed; medial part of head not raised. Antenna with nine antennomeres; last antennomere as long as V–VIII together. Mandibles asymmetrical ( Figs. 5e–f ); left mandible with an immobile incisive tooth and a pair of movable incisive teeth; immobile incisor with two denticles on inner margin; outer margin of mandibles arcuate from base to apex; dorsal face with longitudinal carina, beginning on base of mandible extending toward its outer margin; right mandible similar to the left one, but bearing only an immobile incisor. Maxilla ( Fig. 5g ) with galea and lacinia fused into mala; apex of mala with cuticular teeth; maxillary palp four-segmented; second article twice as long as first one; third article twice as long as second one; apical one very small.

Anterior margin of pronotum arcuate ( Fig. 5a ), almost truncate medially; anterolateral angle pronounced; lateral margin arcuate, oblique on anterior fifth; posterior margin bisinuate, with arcuate part medially; anterior third of pronotum with two pairs of shallow impressions, one medial and other sublateral; posterior half with two pairs of shallow impressions, one near posterolateral angles other sublateral. Scutellar shield very small, subtriangular, slightly longer than wide; anterior margin arcuate, lateral margin converging to acute apex. Anterior margin of elytron arcuate and flattened ( Fig. 5a ); lateral margin subparallel on anterior two thirds, converging on posterior third; elytral formula 8d + 2a(IVa,VIa) + 1sl / 0d + 0sl; striae formed by a row of punctures; accessory striae long; sublateral carina on posterior three-fifths; elytral intervals feebly raised; surface of striae and intervals with iridescent microscales. Epipleuron smooth and wide to level of hind coxa. Hind wing developed ( Fig. 5h ); anterior margin fringed with long setae from radial hinge to anterior region of anal lobe; ScP and RA1+2 extending to radial hinge; RA3+4 beginning on radial hinge, extending toward anterior margin on a feeble sinuosity; RA3+4 borders a pigmented area; RA4 weakly marked, fading before reaching wing margin; RP weakly marked, visible only near the basis; r1 short, not crossing any vein; r4 oblique; MP1+2 well marked, angulate on medial hinge, crossing rp-mp1 and rp-mp2, forming oblong cell; cubital vein parallel to MP1+2, extending toward posterior margin of wing, reaching AA3, which extends to posterior margin; AP3+4 well marked following the margin of anal lobe, which is small and narrow. Anterior margin of prosternum arcuate and crenulate ( Fig. 5b ); prosternal carinae parallel from anterior margin to the procoxae; posterior margin of prosternal process wide and arcuate. Anterior margin of mesoventrite with three gibbosities; medial gibbosity larger than the others, fitting in an internal concavity on prosternum; anterior half of mesoventrite with a transverse fusiform depression which fits the posterior margin of prosternal process. Metaventral carinae complete; metaventral tubercles absent. Anterior face of profemur with a shallow depression on distal two thirds, to fit the fore tibia; protibia with a row of setae on anterior face; meso- and metafemora with shallow depression to fit meso- and metatibiae, respectively; tarsi foursegmented; third tarsomere twice as long as tarsomeres I–II together; fourth tarsomere twice as long as the third one.

Abdomen with ventrites iridescent; carina present on first ventrite, extending from anterior to posterior margin; last ventrite with a pair of weak longitudinal carinae. Male genitalia ( Figs. 5i –j ) with long parameres, not reaching half of phallus length; each paramere with a pair of apical setae, as long as half of paramere length; phallus curved from base to apex in lateral view; apex of phallus digitiform with a pair of setae on dorsal region.

Female: unknown.

Variation. Total length: 1.76¯ 1.83 mm; maximum head width: 0.32¯ 0.33 mm; pronotal length: 0.31¯ 0.33 mm; maximum pronotal width: 0.55¯ 0.60 mm; elytral length: 1.12¯ 1.25 mm; maximum elytral width: 0.40¯ 0.41 mm.

Comparative notes. Ytu coeus sp. nov. is similar to species of the Ytu zeus group, because of the presence of a carina on ventrite 1 and its length greater than 1.4 mm. It is especially similar to Ytu zeus Reichardt because both species present nine elytral striae (8p + 1sl). Ytu coeus sp. nov. lacks prosternal and metaventral setae (“metasternal hairs” in Reichardt & Vanin 1977), as in Ytu zeus . The male genitalia of Ytu coeus sp. nov. resemble those of the Ytu phebo group (Reichardt & Vanin 1977, figs. 13̄17).

Etymology. This species is named after Coeus, the Greek Titan God of intellect, in reference to its similarity to Y. phebo group, especially on genitalia characteristics; Coeus was a brother and consort of Phoebe.

Type material: Holotype. Male. Brasil, Espírito Santo, Dores do Rio Preto, Pedra Menina, Parque Nacional do Caparaó , abrigo Casa Queimada , riacho de laje, nascente do Rio São Domingos , 20°27’21.6”S; 41°48’30.8”W, 2211m alt., 05.I.2013, Col.: Sampaio, B.H.L. [ DZRJ 5650 ] ; paratype: 1 male— same data as holotype, Cachoeira Sete Pilões , 20°28’56.8”S; 41°49’50.3”W, 1869m alt., 06.I.2013, Col.: Sampaio, B.H.L. [ DZRJ 5661 ] ; 1 male— Brasil, Ceará, Ubajara, Parque Nacional de Ubajara, trilha Araticum, Rio da Minas , 3°50’3”S; 40°54’18”W, 524m alt., 19.III.2013, Col.: Santos, A.P.M.; Takiya, D.M. [ DZRJ 5651 ] .

Figures

FIGURE 5. Ytu coeus sp. nov.: a̅b: habitus, a) dorsal view, b) ventral view; c) labrum, dorsal view; d) clypeus, dorsal view; e̅f: mandibles, dorsal view, e) left mandible, f) right mandible; g) right maxilla, dorsal view; h) right hind wing, dorsal view; i̅j: aedeagus, i) dorsal view, j) lateral view.(Scale bars:a̅b:0.5 mm; c̅g: 0.1mm; h: 1 mm; i̅j: 0.2 mm).