Piestus heterocephalus Fauvel, 1902

Caron, Edilson, Ribeiro-Costa, Cibele S. & Newton, Alfred F., 2008, New position of an abdominal defensive gland complex in Staphylinidae (Coleoptera) with redescription of Piestus heterocephalus Fauvel, 1902 (Piestinae), Zootaxa 1895, pp. 1-9 : 3-6

Piestus heterocephalus Fauvel, 1902

( Figs. 1–17 )

Piestus heterocephalus Fauvel, 1902: 22 (original description); Blackwelder, 1944: 100 (Neotropical checklist; error: Fauvel 1865); Herman, 2001: 1791 (world catalog).

Piestus (Piestus) heterocephalus: Bernhauer & Schubert, 1910: 7 (world catalog); Scheerpeltz, 1952: 285 (characters in key).

Type material. Holotype deposited at IRSNB, sex undetermined, labels: 1) “Merida / Venezuela ” [Fauvel’s handwritten]; 2) “ heterocephalus / Fvl.” [Fauvel’s handwritten]; 3) “R.I.Sc.N.B. 17.479 / Piestus / Coll. et det. A. Fauvel”; 4) “Ex-Typis” [white label, written in red].

Additional material (7ɗɗ, 6ΨΨ, 14 sex undetermined). COLOMBIA: Valle del Cauca: Ψ, 1 specimen, Cali, no date, Fassl coll. (1 AMNH, 1Ψ NMW); 1 specimen, ditto but 30.VI.1938, Dybas coll. ( FMNH); 1 specimen, Cali, S. Antonio, 2000 m, VII.1908, Fass coll. ( FMNH); 1 specimen, ditto but 21.VII.1908 ( NMW); 1 specimen, ditto but 27.VII.1908 ( NMW); 1 specimen, ditto but III.1909 ( FMNH); ɗ, ditto but I.1909 ( FMNH); 1 specimen, Cali, Villa Elvira, 1800 m, 6.VII.1908, Fass coll. ( FMNH); 1 specimen, ditto but 12.IX.1908 ( NMW); 1 specimen, Cali, Alto de las ances, XI.1908, Fass coll. ( NMW); 1 specimen, Cali, Rio Vitaco, 2200 m, XII.1908 Fassl coll. ( FMNH); Ψ, Pischindé, no date, Rosemberg coll. ( IRSNB); VENEZU- ELA: Mérida: 1 specimen, Mérida, no date and collector [“Ex-Typis”, see remarks below] ( IRSNB); ECUA- DOR: Pichincha: 1 specimen, Calicali, 1800 m, 19.XII.1987, Huybensz coll. ( FMNH); 1 specimen, Tandapi, 1300–1500 m, 15–20.VI.1965, Pena coll. ( FMNH); Cotopaxi: 6ɗɗ, 4ΨΨ, Sigchos, Las Pampas Otonga Natural Reserve, 25–28.VII.2005, W. Rossi coll. ( DZUP); El Oro: 1 specimen, 12 km NW Atahualpa, 1780 m, wet forest, 6.XI.1987, Young, Davidson & Rawlins coll. ( FMNH).

Redescription. BL: 7.25–9.92 mm, BW: 1.80–2.40 mm.

Body reddish dark brown to black with golden setae, apical half of abdominal segment VII and segments VIII–X yellowish ( Figs. 1, 2 ); antenna with apex of antennomere 11 slightly lighter than the others; tarsi, maxillary and labial palpi lighter than body.

Integument with undulate microstriae ( Fig. 3 ), except on elytra; finely punctuate; larger punctures on lateral regions of metaventrite, on anterolateral regions of tergites and uniformly distributed on sternites.

Male. Head transverse ( Fig. 3 ); front with two lateral long frontal processes, each almost reaching the dorsal tooth of mandibles ( Fig. 4 ), ventral face coarsely serrate, basal distance between the processes 2.0 times the width of each one ( Fig. 3 ); vertex with anterior angles curved and prominent ( Fig. 3 ); V-shaped sulcus incomplete with curved arms not joined medially ( Fig. 3 ); two moderate punctures with long setae on dorsal margin of the salient eyes, basal seta a little longer than apical seta ( Fig. 4 ). Antennae somewhat geniculate and long, reaching the apex of elytra ( Figs. 1, 2 ); scape about 2.0 times the length of pedicel and with a tuft of five long setae on apical half of dorsal face. Labrum transverse ( Fig. 9 ), anterior margin slightly emarginate with six setae medially, equal in length; on lateral 1/3, the antero-internal seta with same length as posteroexternal seta. Epipharynx visible dorsally, about 2.0 times the median length of labrum ( Fig. 9 ), deeply emarginate medially, with long fringes on internal margin and short fringes on external margin. Mandibles projected ( Fig. 4 ), longer than the scape; slightly asymmetric ( Fig. 10 ), each with bifurcate apex, the dorsal tooth shorter than the ventral; the internal border with one acute tooth at the middle and, anterior to it, in the right mandible with an area that resembles a tooth, absent in the left mandible. Mentum about 2.0 times wider than long. Pronotum somewhat wider than long (PW/PL=1.30) ( Fig. 1 ), slightly convex ( Fig. 2 ), with parallel sides and abrupt constriction at basal 1/4 ( Fig. 1 ); conspicuous longitudinal median sulcus not reaching anterior and posterior margins. Elytra truncate ( Fig. 1 ), together somewhat longer than wide (EL/BW=1.15); each with five longitudinal striae, sixth stria only on basal 2/3 of elytra; interstria 1 wider than the other ones. Abdominal sternite VI with very small emargination on each posterolateral area (external openings of abdominal defensive gland complex) ( Fig. 5 , arrow; Figs. 6 , 11 ); sternite VII with anterior margin broadly but shallowly projected above sternite VI ( Figs. 6 , 11 ), the projection immediately under the cell mass of the defensive gland ( Fig. 17 ) and bearing some glandular pores (see separate description of gland complex below); apex of sternite VIII slightly curved; tergite X separating tergite IX in two equal parts, contiguous at base of tergite X; tergite IX with ventral struts short; tergite X with two pairs of setae, the apical pair the longest, about 2.0 times the length of the subapical ( Fig. 12 ); sternite IX weakly pigmented, composed of a single median sclerite, symmetrical, 3 times longer than wide, basal margin acute, apical margin rounded, with two short setae on the apex. Aedeagus with median lobe curved in lateral view ( Fig. 13 ), bulbous base ( Fig. 14 ); lateral lobes exceeding the apex of median lobe by 1/4 of its length in lateral view, with short setae apically and apex of external margin truncate ( Fig. 13 ).

Female. Identical to male except for apex of sternite VIII slightly acute; tergite IX without ventral struts; area of sternite IX, which lacks a median sclerite and instead has an ovipositor consisting of a pair of very weakly pigmented hemisternites and a pair of more apical coxites with external margin somewhat rounded, and with a short seta and some microsetae on the apex; stylus absent ( Fig. 15 ). Spermathecal duct short and sclerotized at base ( Fig. 16 ); spermatheca with basal half narrower than the apical.

Remarks. In the original description of P. heterocephalus, Fauvel (1902) specified only one specimen studied (“Un seul exemplaire.”) and provided only data of locality (“ Venezuela: Merida.”). However, we received from IRSNB two specimens with locality label (“Merida / Venezuela ”—presumably Fauvel’s handwritten), an additional museum label with information about Fauvel’s collection, and a type label (“Ex- Typis”), but only one specimen has an identification label (“ heterocephalus / Fvl.”—presumably Fauvel’s handwritten). This was the main reason why we considered one specimen as the holotype (with Fauvel’s identification label) and the other as additional material (without Fauvel’s identification label).

This species is similar to P. l a c o rd a i re i Laporte, 1835 mainly by the similar distance between the frontal processes of the head (2.0 times the width of each process). However, P. heterocephalus differs by the black body with apical half of abdominal segment VII and all of segments VIII–X yellowish ( Figs. 1, 2 ) (body entirely light brown to dark brown in P. lacordairei ); ventral face of frontal processes of the head coarsely serrate ( Fig. 4 ) (only a short tooth on basal half in P. lacordairei ); the labrum with six setae medially on anterior margin ( Fig. 9 ) (four in P. lacordairei ); and the lateral lobes of the aedeagus with truncate apex on external margin ( Fig. 13 ) (curved in P. l a c o rd a i re i).

Piestus heterocephalus may be confused with P. b i c o r n i s ( Olivier, 1811) or P. v a l i d u s Sharp, 1876 because they share a similar body coloration. However, in P. b i c o r n i s and P. v a l i d u s the basal distance between the frontal processes of the head is equal to the width of each process and the lateral lobes of the aedeagus are short, never exceeding the apex of the median lobe.

Distribution. Old records: Venezuela ( Herman 2001). New records: Colombia, Venezuela and Ecuador.

Figures

FIGURE 17. Piestus heterocephalus Fauvel, 1902. Sternites V – VII dorsal view, tergites and left reservoir removed. Scale: 1 mm.

FIGURES 1 – 8. Piestus heterocephalus Fauvel, 1902. 1) habitus, dorsal view; 2) habitus, lateral view; 3) head, dorsal view; 4) head, lateral view; 5) sternites VI and VII, ventrolateral view (arrow: external opening of the defensive gland); 6) sternites VI and VII, ventral view; 7) sternites VI and VII, dorsal view, tergites removed, micrograph; 8) micrograph showing details of reservoir and of cell mass.

FIGURES 9 – 16. Piestus heterocephalus Fauvel, 1902. 9) labrum and epipharynx, left epiphayneal lobe and right setae removed; 10) mandibles, apex in dorsal view; 11) sternites VI and VII, ventral view, gently separated; 12) tergite X, apex, dorsal view; 13 – 14) aedeagus, 13) lateral view, 14) ventral view; 15) sternite IX, female, ventral view; 16) spermatheca. Scales: 0.25 mm, except Fig. 11: 1 mm.