Polylobus

Silva, Sidnei Bortoluzzi Da & Caron, Edilson, 2014, The unique Brazilian species of Polylobus Solier (Coleoptera: Staphylinidae: Aleocharinae) with a checklist of all species of the genus, Zootaxa 3811 (2), pp. 226-238 : 227-228

Polylobus stigma ( Erichson, 1839)

( Figs 1–7 )

Homalota stigma Erichson, 1839: 120 (original description, type locality: “ Brasilia ”). Atheta (Microdota) stigma: Bernhauer & Scheerpeltz, 1926: 635 (distribution). Tricolpochila stigma: Pace, 1987b: 170 (characters, lectotype designated).

Polylobus stigma: Pace, 2000: 400 (mention); 496, 498 (characters).

Type material. Homalota stigma Erichson, 1839. Syntype deposited in ZMHB, female, dissected, body glued on white board; maxila, labium and spermatheca mounted on the first plastic slide [presumably dissected by Pace in 1983], and right protarsus, tergite 8 and segments 9–10 [dissected by the current authors], both imbedded in Canada Balsam; labels: (1) ‘5417’ [old white label, printed in black]; (2) ‘ stigma ’ [old white label, handwritten]; (3) ‘Typus’ [red label, printed in black]; (4) ‘ stigmusa / stigma (Er.)/det. R. Pace 1983’ [white label, 1st and 2nd lines handwritten and the 3rd line printed in black, with the decade of the year handwritten]; (5) ‘ stigma /Er/ Brasil. Gm.’ [green label, handwritten]; (6) ‘Zool. Mus. Berlin’ [yellow label, printed in black]; (7) ‘ SYNTYPUS / Homalota / stigma Erichson, 1839 / labeled by MNHUB 2013’ [red label, printed in black]. Note 1: In the original description Erichson (1839) did not specify how many specimens he studied. We received from ZMHB only one specimen labelled as type, here named syntype. Note 2: Pace (1987b) published the lectotype designation of Tricolpochila stigma, however the designation label in the type material is missing. Note 3: we received the type material with labels organized in that sequence.

Redescription. Female. Maximum body length: 3.0 mm; maximum elytra width: 0.9 mm. Body broad; sides subparallel; uniformly light-brown with darker spot on tergite 6; dorsal surface glossy; setigerous pores sparse and more densely on head, pronotum and elytra; pronotum with pubescence directed latero-posteriad; elytra and abdomen with pubescence straight and direct posteriad.

Head as long as wide; eyes about as long as temples; infraorbital carina complete. Antennal article 2nd slightly shorter than 1st and longer than 3rd; article 4th subquadrate, articles 5–10 transverse and gradually increasing in width toward antennal apex; article 10th twice as wide as long; article 11th as long as articles 8–10 combined. Mandibles broad and curved at apex. Maxila with galea extending slightly beyond apex of lacinia ( Fig. 1 ), galea narrower than lacinia; apical lobe of galea covered with fine and short setae; internal margin of galea with long subapical setae; apical 1/3 of lacinia with a row of spines, middle portion covered with numerous setae; maxillary palpus with 4 articles, 2nd slightly shorter than 3rd, and 4th about half length of thepreceeding one. Labium with ligula split into two lobes ( Fig. 2 ); labial palpus with 3 articles, 1st the longest and 2nd the shortest.

Pronotum transverse, 1.5 times as wide as long, broadest at basal half, anterior margin straight, lateral and posterior margin convex; hypomera invisible in lateral view. Prosternum transverse. Elytra slightly broader than pronotum; 1.2 times as long as pronotum; posterior outer corners deeply emarginated. Hind wings fully developed. Mesoventrite process about half length of mesocoxae, acute and sharp at apex, mesocoxae contiguous, mesocoxal cavities weakly or not margined posteriorly; isthmus almost the same length as mesoventrite process; metaventrite process almost not existent. Tarsal formula 5-5-5; tarsomere 5 the longest ( Fig. 3 ), as long as 3rd and 4th combined.

Abdomen gradually narrowing apically, first four visible terga deeply impressed basally; segment 7 the longest. Tergite 8 sparsely pubescence in posterior half, bearing three prominent setae at each side ( Fig. 5 ); posterior margin truncate. Sternite 8 sparsely pubescence in posterior half, bearing one prominent setae at each side ( Fig. 6 ); posterior margin broadly rounded. Tergite 10 slightly emarginated at apex and fused with tergite 9 medially ( Fig. 7 ). Spermatheca L-shaped ( Fig. 4 ); subspherical capsule, with slightly invaginated apex.

Male. Unknown.

Distribution. Brazil. In the original description ( Erichson 1839), and on the label of the type material there is not precise information about the locality, only that the material was donated by Germar ( Erichson 1839), presumably Ernst Friedrich Germar.

Bionomics. Unknown.

Taxonomic note. Pace (1987b: 170) compared Polylobus stigma with Tricolpochila topaliana ( Scheerpeltz, 1972) , and in Pace (2000: 496, 498) compared P. s t i gm a with P. valparaisensis Pace, 2000 and P. granulifer Pace, 2000 , respectively. According to Pace, the characters easily separate P. s t i g m a from them are: length of eyes, punctures on elytra and general form of spermatheca. Unfortunately, in this work it was not possible to compare P. stigma with those species.

Following Klimaszewski & Sturm (1991) the genus have galea with sponge-like apical bristles, not seen in P. stigma. The galea of P. stigma has internal margin with long subapical setae, very similar to the species of Stethusa (Athetini) ( Gusarov 2002, Fig. 12). We also agree with Pace (2000: 400) that Polylobus is forming a complex group, at least with Tricolpochila Bernhauer, 1908 and Polylobinus Bernhauer, 1908 . We tentatively include Polylobus stigma in the genus Polylobus pending further revision of the genus and related genera.

Figures

FIGURES 1 – 4. Polylobus stigma, female. 1 — right maxilla; 2 — labium; 3 — right tarsus; 4 — spermatheca. Scale bar 0.1 mm.

FIGURES 5 – 7. Polylobus stigma, female. 5 — tergite 8, dorsal view; 6 — sternite 8, ventral view; 7 — tergites 9 – 10, dorsal view. Scale bar 0.25 mm.