Delius robustulus Casey

Jałoszyński, Paweł, 2017, Status of Nearctic subgenera of Microscydmus revisited (Coleoptera, Staphylinidae, Scydmaeninae), Zootaxa 4358 (3) : -

Delius robustulus Casey , stat. rest.

( Figs 2, 5 , 8, 11 , 14 , 16–17 )

Delius robustulus Casey, 1897: 497 .

Microcydmus (Delius) robustulus (Casey) ; Franz, 1985: 176.

Type material studied. Lectotype (here designated): ♂: six labels ( Fig. 5 ): "St. Vinc. / Penn." [white, printed], "CASEY / bequest / 1925" [white, printed], "10" [white, handwritten], " Delius / robustulus / Casey" [white, handwritten], " Delius / robustulus Casey / Holotypus / det.H.Franz" [white, handwritten and printed], "TYPE USNM / 49122" [red, printed and handwritten] (NMNH). Paralectotype: three labels: "St. Vinc. / Penn." [white, printed], "CASEY / bequest / 1925" [white, printed], "10" [white, handwritten], " robustulus 2 / PARATYPE USNM / 49122" [red, handwritten and printed] (NMNH).

Diagnosis. As in genus, vide supra.

Description. Body of male ( Fig. 2 ) moderately convex with slightly flattened elytral dorsum, elongate, with moderately long appendages, BL 0.86–0.88 mm; cuticle glossy, uniformly light brown; vestiture of setae and bristles slightly lighter than cuticle.

Head ( Figs 2 , 8, 11 ) subhexagonal, broadest at eyes, HL 0.13 mm, HW 0.18 mm; vertex and frons confluent, weakly convex; supraantennal tubercles feebly marked; eyes large, strongly convex and coarsely faceted. Punctures on vertex and frons fine and inconspicuous; setae short, sparse, suberect, tempora and genae with moderately dense, long bristles. Antennae ( Fig. 2 ) short, AnL 0.35 mm; scape and pedicel elongate, scape slightly longer than pedicel, antennomeres III–IX distinctly transverse, XI shorter than IX and X combined, about as long as broad.

Pronotum ( Figs 2 , 8 ) in dorsal view subtrapezoidal, broadest in anterior third, PL 0.23 mm, PW 0.23 mm; anterior margin rounded and confluent with lateral margins, which are strongly rounded in anterior half and weakly sinuate in posterior third; posterior corners obtuse-angled and blunt; posterior margin indistinctly bisinuate; four antebasal pits shallow and small, lateral pair obscured by bristles, inner pair connected by a short transverse groove (poorly visible in Fig. 8 ) and separated much more narrowly than each inner and lateral pit. Punctures on pronotal disc as fine as those on frons and vertex; setae short and sparse, suberect, sides and lateroventral portions of hypomera densely covered with thick bristles.

Elytra ( Fig. 2 ) suboval and slightly flattened, broadest in front of middle, EL 0.51–0.53 mm, EW 0.33–0.35 mm, EI 1.50–1.58; basal impressions shallow and short, humeri elongate; apices separately rounded. Punctures on elytral disc slightly more distinct than those on head and pronotum but superficial and diffuse; setae sparse, short, suberect.

Hind wings not studied.

Legs moderately long and slender; unmodified.

Aedeagus ( Figs 16–17 ) stout, AeL 0.10 mm, thin-walled, median lobe symmetrical, with circular ventral diaphragm, endophallic structures asymmetrical, weakly sclerotized and relatively simple; parameres broadened in apical region and curved dorsally, each with two tiny subapical setae.

Distribution. Pennsylvania.

Lectotype designation. Casey (1897) mentioned two specimens, and despite Franz's interpretation of one of them as a holotype, they have a status of syntypes. Specimen illustrated in Fig. 2 , with labels as in Fig. 5 , is here designated as lectotype for Delius robustulus Casey, 1897 .

Figures

FIGURES 1–6. Microscydmus (Opresus) misellus (LeConte) (1, 4); Delius robustulus Casey (2, 5); Neladius tenuis Casey (3, 6). Dorsalhabitus of lectotypes (1–3) and their historical sets of labels (4–6).

FIGURES 7–12. Microscydmus (Opresus) misellus (LeConte) (7, 10); Delius robustulus Casey (8, 11); Neladius tenuis Casey (9, 12). Head, pronotum and elytral bases in dorsal view (7–9); head, prothorax and anterior portion of pterothorax in ventral view (10–12). Abbreviations: abp, antebasal pit; bef, basal elytral fovea; bst, basisternal part of prosternum; hr, hypostomal ridge; hyr,hypomeral ridge; lss, lateral suture of submentum; nss, notosternal suture; pcr, procoxal rest.

FIGURES 13–15. Microscydmus (Opresus) misellus (LeConte) (13); Delius robustulus Casey (14); Neladius tenuis Casey (15); pterothorax and abdomen in ventral view. Abbreviations: msvp, mesoventral intercoxal process; mtvp, metaventral intercoxal process; pcr, procoxal rest; pm, paramere; stVII–VIII, abdominal sternite VII–VIII.

FIGURES 16–19. Delius robustulus Casey (16–17); Neladius tenuis Casey (18–19). Aedeagus in ventral (16, 18) and lateral (17, 19) views.