Corotoca pseudomelantho Zilberman, 2018

Zilberman, Bruno & Casari, Sônia A., 2018, New species of Corotoca Schiødte, 1853 from South America and description of first instar larva, Zootaxa 4527 (4), pp. 521-540 : 522-525

Corotoca pseudomelantho Zilberman , sp. nov.

Female: Length 2.5–3.5 mm (figs. 1–3, 75) Male: Length 2.1–2.3 mm (figs. 4–6, 74)

Body partially membranous with abdomen inclined upwards and strongly physogastric, semicircular in lateral view. More sclerotized portion of head, pronotum, legs and sternites light brown; vertex and sternites VII and VIII darker (except for secondary sclerotization, which is lighter). Membranous area milky-white. Anterior region of post-mentum membranous, clypeus present and pronotum with two pairs of setae. Some specimens have headpronotum and pronotum–mesonotum slightly to strongly separated by areas of exposed membrane (usually accentuated in males).

Head. Transverse, widest behind eyes; gula subtriangular, widest at base, fused to mentum; foramen magnum occupying 2/3 of head width; vertex with a transversal row of four long setae. Clypeus present (figs. 7, 64). Antennae with 11 antennomeres; scape elongate, gradually widened towards apex; antennomere II subquadrate; antennomere II subquadrate and antennomeres III–X decreasing gradually in size; antennomeres III, X, each with one sensillum at apical region ( Figs. 7, 8 ); last antennomere longer than IX, X or VIII and the same length of VII, with a pair of sensilla at medial region.

Mouthparts. Labrum membranous, about two times wider than long; four to five main setae on each side, with P2 with presence variable, more basal; setae M2-D2-M 1 in a lateral-medial row and D 1 in more apical region; lateral margin strongly round (figs. 10, 66). Mandibles symmetrical, narrow, with internal margin with a subapical mesal, short and stout tooth; subapical region bent and spoon-like (fig. 9). Maxillae with cardo semitriangular; stipes broad, 1/3 wider than long; lacinia subquadrate and galea narrow, same length of lacinia; maxillary palpi densely setose and with four palpomeres: palpomere I short, II subcylindrical, III suboval and IV reduced; three first palpomeres covered with long setae and last by short setae (fig. 11). Labium. Pre-mentum with labial palpi setose, 3-articulated; palpomeres I and II subquadrate; last elongate and narrow; mentum fused to sub-mentum (post-mentum), with anterior margin membranous, not well-delimited; four long setae distributed in two pairs, one on each margin: apical (ap) and proximal (px) (figs 12, 13, 63).

Prothorax. Pronotum two times wider than long; anterior margin emarginated, with two pairs of setae: one located in lateral-medial and other in lateral margin (figs. 2, 5, 69). Mesothorax. Mesonotum slightly longer than metanotum; mesosternum fused to metasternum. Metathorax with endosternite bearing an extended medial articulating process, with median basal region emarginated and rounded in general aspect; a dark spot lonsangeshaped in medianbasal region present, lighter in males. Elytra covering meso and metathorax, with internal margin oblique in relation to elytra length; outer, posterior angle narrow (fig. 19). Wings present with typical staphylinid venation. Legs well-developed; posterior tibia with apex surrounded by depression; with a longitudinal row of long setae at inner side. Scutellum semi-fusiform (figus 14–18).

Abdomen mostly membranous, strongly bent at segment II level; sclerites composed by tergites and sternites, without paratergites; segment I composed only by the tergite I, which is reduced and attached to metanotum, with margin of medial region projected backwards. Segment II composed by a transverse tergite with margins broad; internal area short and deep; segments III–X composed each by complete tergite and sternite, except in female which sternite IX is absent; tergites IV and V with long lateral extension, fused along their length, almost encircling the abdomen; sternite IV in male sclerotized in medial region; membranous in female; sternites V and VI transverse, larger than long; in females, sternites V–VII with elongated setae, shorter in males; medial row of setae present in sternites V–VI of female and absent in male; sternite VII oblique in lateral view, in relation to abdomen length; apical region of tergite VIII with a pair of main setae on each side (p2-p1) and sternite VIII wider than long, with three to four setae on each side on apical region; sternite IX on male mostly membranous, sub-triangular; four setae symmetrically distributed apically; tergite IX sub-triangular and bilobed, each lobe with three long setae; tergite X divided in two elongate portions, each bearing one to two long setae (figs. 20–23, 77). Aedeagus with lateral lobes perpendicular to median lobe, about same length (fig. 24). Spermatheca elongate and sclerotized (fig. 25).

Figures

FIGURES 7–13. Corotoca pseudomelantho Zilberman,sp. nov. 7, head (ventral); 8, antenna; 9, mandibles; 10, labrum; 11, maxilla; 12, labium; 13, post-mentum (arrow indicating non-delimitated area). Scale bars = 0.1 mm, except figs. 8 = 0.5 mm, 10, 13 = 0.05 mm.