Peplomicrus nidicola Jałoszyński & Sapieja, 2023

Jałoszyński, Paweł & Sapieja, Mateusz, 2023, A new species of Peplomicrus Bernhauer from Ecuador (Coleoptera, Staphylinidae Micropeplinae), Zootaxa 5239 (3), pp. 442-450 : 443-449

Peplomicrus nidicola Jałoszyński & Sapieja sp. n.

( Figs 1–15 )

Type material studied. Holotype: ECUADOR: ♁, two labels: “ Ecuador 54, Napo prov., / Rio Hollin , nests of Icteridae , / 1068m, 00°43′S / 77°38′W, / 6 XII 2009, leg. Rafał Ruta ” [white, printed], “ PEPLOMICRUS / nidicola / Jałoszyński & Sapieja, / 2022, HOLOTYPUS” [red, printed] ( MNHW) . Paratypes (12 exx): 6 ♁♁, 6 ♀♀, same data as for holotype . Paratypes with yellow “PARATYPUS” labels similar to that with holotype, deposited in MNHW, cMS, cPJ and cRR .

Diagnosis. Median longitudinal impression on metaventrite shallow, with diffuse margins, extending from posterior region of metaventral intermesocoxal process nearly to posterior metaventral margin, flanked by pair of short and barely discernible elongate impressions situated near middle of metaventral length; aedeagal apex subtrapezoidal in dorsal view and subtriangular in lateral view.

Description. Body of male ( Figs 1–6 ) stout, weakly convex; pigmentation dark brown with slightly darker head and distinctly lighter margins of frons, clypeus, and pronotum, also lateral translucent regions of pronotum light brown; appendages light brown, except for infuscate antennal club; cuticle on dorsal side glossy except for strongly microreticulate and matt frons, vertex, median and lateral regions on pronotum. BL 1.31–1.43 mm.

Head broadest at eyes, nearly twice as wide as long and as wide as anterior pronotal margin; HL 0.16–0.19 mm, HW 0.35–0.38 mm.Tempora short and just behind each eye developed as minute temporal denticle projecting laterally, behind denticle tempora strongly convergent posterad. Posterior margin of vertex arcuate, convex anteriorly, vertex with narrow posteromedian longitudinal carina anteriorly reaching almost half-length of eyes. Eyes large, round, distinctly projecting from outline of head, coarsely faceted. Frons strongly transverse, shallowly impressed along midline and elevated at sides Anterior margin of frons forming slightly raised transverse and broadly rounded ridge with shallow subtriangular anteromedian emargination. Dorsum of head with distinct, reticulate microsculpture, indistinct only in median impression on frons. Frons and vertex impunctate and sparsely covered by extremely short erect setae, discernible only on SEM close-ups. Antennae with composite club formed by antennomeres 9–11 fused together. AnL 0.30 mm. Antennomere 1 strongly elongate, narrow at base and strongly broadening to distal 1/3, then strongly narrowing distally, 2 slightly narrower than 1, broadest near basal 1/3 and gradually narrowing distad, 3–6 each elongate, 7 about as long as wide, 8 distinctly transverse, club 1.5 times as wide as antennomere 8, oval, broadest near proximal 1/3 and with blunt subconical apex.

Pronotum trapezoidal, strongly transverse, equally broad from base to middle, much wider than head, distinctly narrower than elytral base but as wide as widest site of elytra; PL 0.30–0.33 mm, PW 0.58–0.60 mm. Anterior pronotal margin deeply bisinuate, broadly subtrapezoidal at middle and emarginate in sublateral regions; anterior pronotal corners slightly obtuse-angled and with acute tips; lateral margins in anterior half straight and strongly converging anterad, parallel in posterior half, where they bear two minute triangular, subacute denticles. Posterior pronotal corners weakly sharp-angled and with acute tip forming third lateral denticle. Posterior pronotal margin posteriorly convex in median region. Pronotal disc with three pairs of longitudinal ridges: median pair extending from anterior to posterior pronotal margin, delimiting median elongate impression distinctly broadened slightly in front of middle; submedian pair extending from posterior margin to middle of pronotum and delimiting pair of elongate submedian impressions; and sublateral oblique pair extending from posterior to anterior pronotal margin and subdivided into three weakly curved sections, of which posterior one is extending strongly posterolaterally. Posteriorly, each sublateral longitudinal ridge is connected with arcuate, transverse basal ridge running towards lateral pronotal margin and reaching level of humeral denticle. Submedian and sublateral ridges are connected near posterior third of pronotum by short oblique carina marking border between posterior and median section of sublateral longitudinal ridge. Two pairs of deep circular foveae are situated at junctions between posterior and median and between median and anterior sections of sublateral ridges. Broad lateral regions of pronotal disc explanate. Pronotum finely reticulate, except for narrow areas at each side of sublateral longitudinal ridges, lacking punctures, with sparse and extremely short suberect setae visible only in SEM images under high magnifications.

Each hypomeron with strongly elongate oval antennal cavity adjacent to prosternum and procoxal cavity. Prosternum broadly T-shaped, anterior margin arcuate (anteriorly concave) with minute triangular anteromedian projection; sides rounded; prosternal process nearly parallel-sided with broadly rounded posterior margin; median longitudinal prosternal carina weakly developed, diffuse and feebly elevated; precoxal (basisternal) region of prosternum with four pairs of shallow impressions, sides of prosternal process weakly impressed.

Elytra together subrectangular, distinctly transverse, broadest near posterior 1/5; EL 0.33–0.35 mm, EW 0.59– 0.60 mm, EI 0.54–0.60. Anterior elytral margins weakly convex anteriorly and converging posteriorly; humeral denticles prominent and acute; lateral margin of each elytron bisinuate, slightly concave just in front of middle and with angulate lateral broadening in subapical region. Posterior margin of each elytron broadly rounded with dorsal costae extending posteriorly and forming projections separated by two concave (inner and median) and one straight (outer) sections; middle regions of posterior elytral margins slightly converging anteriorly. Each elytral disc with two round basal foveae situated at outer edge of inner and median costa, with raised adsutural margin, and with three sharply marked and microreticulate costae: inner costa nearly straight and parallel to suture, median costa distinctly convex laterally, and outer costa forming lateral elytral margin in anterior half, and posteriorly slightly curved inwards. Regions delimited by costae slightly impressed and glossy, except for area along mesal margin of outer costa, which is microreticulate; two irregular rows of large round punctures are present between suture and inner costa and between inner costa and median costa, punctures between median and outer costa form three even less regular rows; narrow area along posterior elytral margin impunctate; each elytron with oblique impression extending from base of inner costa to posterolateral corner of scutellar shield. Setae on elytra microscopic, visible only in SEM images, short, sparse and suberect.

Mesoscutellar shield exposed, subtrapezoidal with concave sides and truncate apex, its surface microreticulate.

Mesoventrite with deep oval anteromedian impression to receive posterior region of prosternal process, four lateral impressions (each posteriorly adjacent to mesocoxa), and two posterior impressions (each laterally adjacent to mesocoxa); mesoventral intermesocoxal process broader than diameter of mesocoxa, strongly transverse, with concave sides and nearly straight posterior margin; entire surface of mesoventrite microreticulate.

Metaventrite distinctly wider than long, subrectangular. Metaventral intermesocoxal process broadly subtrapezoidal, with pair of large and circular foveae situated on its median, slightly impressed region, distance between foveae wider than diameter of each fovea. Metaventral intermetacoxal process broader than distance between mesocoxae, subtrapezoidal with nearly straight posterior margin, with minute subtriangular posterior projection at mesal margin of each metacoxa. Median longitudinal impression on metaventrite shallow, with diffuse margins, extending from posterior region of metaventral intermesocoxal process nearly to posterior metaventral margin, flanked by pair of short and barely discernible elongate impressions situated near middle of metaventral length (in Fig. 6 recognizable as longitudinal stripes of sharply marked microreticulation at both sides of median longitudinal impression). Lateral region of metaventrite with outer (adelytral) longitudinal row of three suboval and shallow impressions, and with mesal (postmesocoxal) longitudinal row of two oblique shallow impressions; also admetacoxal region of metaventrite with shallow and diffuse impressions forming transverse arc. Metaventrite largely microreticulate, except for middle of intermesocoxal process and narrow stripe along posterior margin of intermetacoxal process.

Hind wings long and functional.

Legs ( Fig. 6 ) short and moderately slender, unmodified, pro- and mesotibiae nearly straight, metatibiae slightly thickened near proximal third; all podites except for tarsi microreticulate.

Abdomen in dorsal view ( Fig. 1 ) subtriangular with rounded apex, about as long as wide, slightly narrower than pronotum and elytra; in lateral view ( Fig. 4 ), abdominal tergites with weakly rounded dorsal surfaces, posteriorly lowering in a step-wise manner toward abdominal apex situated at sternal plane. AbL 0.50–0.60 mm, AbW 0.50– 0.55 mm. Tergite III largely covered by elytra, partly exposed on sides. Tergites IV–VI each with three pairs of longitudinal rounded carinae extending from anterior to posterior tergal margins; unpaired median carina largely obliterated, developed only in anterior third of each tergite and distinctly less elevated than paired carinae. Tergite VII with three carinae extending from anterior to posterior tergal margin. Posterior margin of tergite VIII ( Fig. 7 ) with shallow, evenly arcuate emargination. Sternite III with one pair of large, circular foveae between metacoxae, and with two pairs of poorly marked longitudinal carinae. Sternites IV–VII each with three pairs of large, circular basal foveae and with three pairs of longitudinal carinae. Posterior margin of sternite VIII ( Fig. 8 ) with deep and broad subtriangular emargination. All paratergites finely microreticulate, dorsal surface of longitudinal carina on all tergites and sternites with shallow microreticulation, microreticulation present also on anterior region of sternite III, and on entire surface of abdominal segments VII–VIII. Setae on abdomen similar to those on head, elytra and ventral pterothorax, microscopic and visible only in SEM images.

Aedeagus ( Figs 9–12 ) strongly elongate, slender, AeL 0.28–0.30 mm. Proximal region of median lobe in dorsal view oval, aedeagus broadest near basal fourth, lateral margins rounded in basal third and nearly straight and converging in distal region. Diaphragm oval, situated in basal third of median lobe.Apex of aedeagus subtrapezoidal. Endophallic structures poorly visible, lightly sclerotized. Parameres appear to be partly fused with median lobe, slender and long, reaching apex of median lobe, each with one short apical seta.

Female. Externally similar to male but with different shapes of tergite and sternite VIII. Tergite VIII ( Fig. 13 ) more elongate than that in male and with rounded apex; posterior margin of sternite VIII ( Fig. 14 ) with narrow and shallow median emargination. BL 1.35–1.38 mm; HL 0.18 mm, HW 0.35 mm; AnL 0.30 mm, PL 0.30–0.33 mm, PW 0.60 mm; EL 0.35–0.38 mm, EW 0.60–0.63 mm, EI 0.56–0.63; AbdL 0.50–0.55 mm, AbdW 0.50–0.55 mm.

Distribution. Ecuador, Napo Province.

Etymology. The noun in apposition nidicola meaning a dweller (- cola) of a nest (nidus) refers to the collecting circumstances.

Remarks. Within the three species groups established by Campbell (1986), P. nidicola matches the diagnosis of the P. dybasi group: the median longitudinal vertexal carina developed only in the posterior region; one pair of presumably glandular pits present on the metaventrite; and the median carina on abdominal tergites IV–VI largely obliterated. This group includes four species: P. dybasi , P. iviei , P. pecki , and P. watrousi . Peplomicrus nidicola differs from all of them in having a shallow but clearly marked and conspicuously long median longitudinal impression on the metaventrite extending from the posterior region of the metaventral intermesocoxal process nearly to the posterior metaventral margin. In the four remaining species of the P. dybasi group, the median longitudinal impression on the metaventrite is present either only in the anterior half ( P. dybasi and P. iviei ), only in the posterior half ( P. pecki ), or is short and developed only in the middle, with a tendency to extend anterad ( P. watrousi ). A pair of impressions flanking the metaventral median longitudinal impression in P. nidicola is barely discernible, in contrast to P. dybasi , P. watrousi and P. iviei , which have these concavities well developed. Based on Campbell’s key (1991) it seems that these impressions do not occur in P. pecki , which, however, clearly differs from P. nidicola in the median metaventral impression developed only in the posterior half of the ventrite.

Figures

FIGURES 1–4. Peplomicrus nidicola sp. n., holotype male. Habitus in dorsal (1), frontolateral (2), frontodorsal (3), and lateral (4) views.

FIGURES 5–6. Peplomicrus nidicola sp. n. SEM images of dorsal (5), and ventral (6) habitus of male.

FIGURES 7–14. Peplomicrus nidicola sp. n. Male tergite VIII (7) and sternite VIII (8); aedeagus in dorsal (9, 11) and lateral (10, 12) views; female tergite VIII (13) and sternite VIII (14).

FIGURE 15. New World blackbirds’ nests where specimens of Peplomicrus nidicola sp. n. were found (photo: Rafał Ruta).