Xanthopygus max Blackwelder, 1944

Chatzimanolis, Stylianos, 2022, A revision of the genus Xanthopygus Kraatz (Staphylinidae: Xanthopygina), Zootaxa 5099 (2), pp. 151-178 : 165-166

Xanthopygus max Blackwelder, 1944

( Figs. 22 , 30–36 )

Lampropygus peruvianus Bernhauer, 1916: 188 .

Xanthopygus max Blackwelder, 1944: 142 (replacement name for peruvianus Bernhauer ).

Type material. Holotype, male, with labels: “ ♂ ” / “ Peru, Chanchamayo [-11.05°, -75.03°], 1500m, Al. Heyne ” / “ peruvianus Bernh. Typus unic” / “Chicago NHMus M. Bernhauer Collection ” / “FMNHINS3975386 Field Museum Pinned” / “ Xanthopygus phylogeny voucher SC-008”. In the collection of FMNH. Bernhauer (1916) indicated that he had only one specimen, therefore this specimen is the holotype.

Diagnosis. Xanthopygus max looks rather similar to X. major and X. pexus and it could be hard to distinguish these three species. In all of these species, abdominal segment 7 is black with posterior 1/2 or posterior 1/3 orange; in X. pexus it is typically 1/2 orange but the degree of coloration can vary. Xanthopygus major and X. max can be distinguished from X. pexus based on the following characteristics in combination: head and pronotum with small to medium size (see Figs. 30–31 ) punctures (medium to large size punctures in X. pexus ); pronotum with one sparse row of punctures on each half beside median line (pronotum with 1–2 dense rows of punctures on each half beside median line in X. pexus ); abdominal segments 4–6 not iridescent under strong light (abdominal segments 4–6 with iridescent overtones under strong light in X. pexus ). Xanthopygus max can be confidently distinguished from X. major only by examining the paramere; in X. max the paramere is apically emarginate, whereas in X. major it is apically rounded.

Description. Forebody length 11.6mm; HW/HL ratio = 1.23. Antennomere 3 longer to 2; antennomere 4 subquadrate, with tomentose pubescence; antennomere 6 transverse. Mandibles curved from apical half. Eyes as long as 1/3 length of head; head appearing convex. Head and pronotum with small to medium size punctures (see Figs. 30–31 ); pronotum with one sparse row of punctures on each half beside median line; pronotum microsculpture with transverse lines. PW/PL ratio = 1.09. Mesoventrite with intercoxal process broad and pointed. Metacoxae with more than four spines (five or six) on posterior surface. EL/PL ratio = 1.53. Abdominal segments 4–6 without iridescent overtones; segment 6 without distinct bright band of orange coloration posteriorly; tergite 6 densely punctate; sternite 6 with single anterior transverse line; segment 7 black with posterior 1/4 orange. In males, sternite 7 without porose structure; sternite 8 with shallow U-shaped emargination posteriorly. Aedeagus as in Figs. 34–36 ; in dorsal view paramere converging to emarginate apex; paramere shorter and narrower than median lobe; in lateral view paramere almost straight; paramere with peg setae as in Fig. 36 . Median lobe in dorsal view converging to narrowly rounded apex; median lobe with subapical tooth; in lateral view median lobe becoming narrower near apex.

Distribution. Known only from the type locality in the department of Junín in Peru. The map is shown in Fig. 22 and online at https://www.simplemappr.net/map/16397.

Habitat. Unknown.

Figures

FIGURE 22. Distribution map of X. luctuosus (Blanchard) (white squares), X. major (Bernhauer) (star), X. max Blackwelder (black squares) and X. oliveirae Lynch (circle).

FIGURES 30–33. Xanthopygus max Blackwelder. 30. Habitus photograph. 31. Pronotum. 32. Sternites 6–8. 33. Antenna. Not to scale.

FIGURES 34–36. Aedeagus of X. max Blackwelder. 34. Dorsal view. 35. Lateral view. 36. Detail of paramere, ventral view.