Scydmaenus (Mascarensia) kasuganus Franz
Creators: name: Jałoszyński, Paweł
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Scydmaenus
Scydmaenus kasuganus

description: Scydmaenus (Mascarensia) kasuganus Franz
Scydmaenus (Mascarensia) kasuganus Franz, 1976: 58. Redescribed by Hoshina, 2007: 2.
Scydmaenus (Mascarensia) honshuensis Franz, 1976: 57. Lapsus for kasuganus.
(Figs 1–26)
Type material examined. Holotype (JAPAN: Nara Pref.): ♂ (Fig. 1), four labels (Fig. 2): „Japan 1974 / lg.H. FRANZ ” [white, printed], “ Mt.Kasuga b. / Nara,Honshu” [white, printed, with “ Ja 126” handwritten on reverse side], “ Scydmaenus / (Mascarensia) / kasuganus m. / det. H.Franz ” [creamy white, handwritten and printed], “Typus” [red, handwritten] (NHMW).
Additional material examined (5 exx). Fukui Pref.: 1 ♂, Hakusan-jinja, 350 m, Shimo-Uchinami, Ono City, 27.04.2003, under bark of deciduous log, leg. P. Jałoszyński (cPJ). Nara Pref.: 1 ♂, 1 ♀, Mt. Kasuga ad Nara, ca. 200 m, 17.05.2002, under bark of dead, standing Quercus tree, leg. P. Jałoszyński (cPJ); 2 ♂♂, Mt. Kasuga ad Nara, 05.05.2001, T. Tsuru leg. (cPJ).
Revised diagnosis. Body length ~ 1.3‒1.4 mm; pronotum about as long as broad; punctures on head inconspicuous, on pronotum fine and dense, on elytra most distinct, conspicuous, deep and dense; pronotal base with only one (inner) pair of pits, which are minute and indistinct; pit on flattened proximal region of metafemur barely discernible; aedeagus with extremely narrow constriction delimiting large and distinctly elongate apical region and tubular proximal portion, in lateral view apical region curved dorsad.
Redescription. Body of male (Figs 1, 3) elongate and weakly convex, light brown with slightly lighter appendages, in some specimens elytra indistinctly darker than head and pronotum; vestiture of setae slightly lighter than cuticle; BL 1.28–1.40 mm.
Head in dorsal view (Fig. 4) broadest at eyes, indistinctly transverse, HL 0.23–0.25 mm, HW 0.28; vertex and frons confluent, evenly convex; supraantennal tubercles feebly marked; tempora nearly three times as long as eye, eyes weakly convex and finely faceted, not projecting from head silhouette, in lateral view (Fig. 5) oval, posteriorly emarginate. Dorsal surface of head virtually impunctate and covered with sparse, short and suberect setae. Antennae (Figs 4–6) slender, as long as about half of body length, AnL 0.65–0.73 mm; scape and pedicel strongly elongate, antennomeres 3–5 each elongate (5 the longest) and symmetrical, 6–8 each distinctly asymmetrical, with mesal margin shorter than external one, antennomere 6 slightly elongate, 7 and 8 each about as long as broad, antennomeres 9–11 forming distinct and symmetrical club covered with setae denser than those on remaining antennomeres, 9 slightly elongate, 10 about as long as broad, 11 slightly broader than 10, much shorter than 9 and 10 combined, 1.4 × as long as broad.
Mouthparts (Figs 7–10) directed anterad. Labrum (Fig. 7) strongly transverse and bilobate, with broad and deep median U-shaped emargination flanked by short tooth, sides broadly rounded, dorsal surface with anteriorlydirected almost symmetrically and sparsely distributed long setae; epipharynx with 6–7 conspicuously long setiform sensilla (Fig. 7; ephs) projecting far beyond anterior labral margin and well-visible in dorsal view. Mandibles (Fig. 8) asymmetrical, falciform, long and in closed position overlapping, each with broad base and long setose prostheca (Fig. 8; pst) and slender distal region with sharp apical tooth; left mandible with two separate preapical teeth (Fig. 8; pat), right mandible with one preapical tooth with bifid apex. Maxilla (Fig. 9) with semicircular cardo (Fig. 9; ca), elongate, subtriangular basistipes (Fig. 9; bst), elongate and quadrangular mediostipes (Fig. 9; mst); maxillary palpomere inserted on elongate palpifer (Fig. 9; ppf) and composed of four palpomeres: palpomere 1 (Fig. 9; mxp1) minute, elongate, palpomere 2 (Fig. 9; mxp2) pipe-shaped, strongly elongate, palpomere 3 (Fig. 9; mxp3) the largest, narrow at base, broadening to nearly middle and then indistinctly narrowing toward truncate apex, palpomere 4 (Fig. 9; mxp4) dome-shaped, densely setose. Labium (Fig. 10) with submentum (Fig. 10; smn) not demarcated posteriorly, its anterior margin straight at middle and its anterolateral corners forming subtriangular projections; mentum (Fig. 10; mn) rectangular with slightly rounded sides, distinctly transverse, with weakly concave anterior margin; prementum (Fig. 10; pmn) largely membranous, with non-differentiated ligula and trimerous labial palps: palpomere 1 (Fig. 10; lp1) slightly shorter than long, palpomere 2 (Fig. 10; lp2) the longest, about 3 × as long as broad and nearly cylindrical, palpomere 3 (Fig. 10; lp3) minute, nearly aciculate; lateral lobes of hypopharynx (Fig. 10; llh) short and inconspicuous.
Pronotum in dorsal view broadest near anterior third; PL 0.35–0.38 mm, PW 0.35–0.38 mm; anterior margin and sides in anterior third rounded, sides in posterior half indistinctly rounded or nearly straight and strongly converging posterad; posterior margin arcuate, with median region slightly more profoundly projecting posterad; base with one pair of small, shallow and poorly marked pits. Pronotal disc distinctly punctate, punctures small and shallow but well-discernible, those on median area separated by spaces subequal to or slightly shorter than their diameters, punctures reducing in diameters and depths toward pronotal margins. Setae on disc moderately dense, short and suberect. Prosternum with its basisternal region (Fig. 11; bst) slightly longer than coxal region and laterally indistinguishably fused with convex hypomera (Fig. 11; hy).
Mesonotum (Fig. 12) with mesoscutum (Fig. 12; sc2) and mesoscutellum (Fig. 12; scl2) fused so that scutoscutellar suture is indiscernible, scutellar shield not exposed between elytral bases in intact specimens, with broadly rounded posterior margin.
Metanotum (Fig. 13) as in all winged Scydmaenus species, with strongly shortened alacristae (Fig. 13; alc) not reaching middle of scutum; metascutum and metascutellum fused (Fig. 13; sc+scl3). Prescutum (Fig. 13; prsc) relatively long, with well-visible median phragma; metapostnotum (Fig. 13; pn3) long and subtriangular, with broadly rounded posterior margin.
Mesoventrite (Fig. 14) strongly transverse, with massive prepectus, pair of weakly concave and asetose anteromedian impressions functioning as procoxal rests (Fig. 14; pcr) and mesocoxal projections weakly projecting laterad; mesoventral intercoxal process (Fig. 14; msvp) broad and nearly parallel-sided.
Metaventrite (Fig. 4) about as long as broad, slightly trapezoidal, broadening posterad up to posterior 1/6 and then narrowing, with distinctly rounded sides. Mesocoxal rests nearly circular, carinate posteriorly; metaventral intercoxal process (Fig. 14; mtvp) short and broad, with posterolateral subtriangular projections. Metaventrite unmodified. Metanepisterna (Fig. 14; aest3) broad and largely separated from metaventrite, but fused to it near posterolateral margins of mesocoxal rests.
Elytra (Figs 1, 3, 15) together oval, broadest slightly in front of middle, EL 0.70–0.78 mm, EW 0.48–0.56 mm, EI 1.38–1.47. Humeral calli prominent; basal impressions and basal foveae lacking; basal articulating lobe delimited from disc by anteriorly concave step-wise ridge. Elytra covered with punctures larger and deeper than those on pronotal disc, slightly unevenly distributed, so that some punctures touch each other, and some are separated by spaces subequal to their diameters; punctures reducing in diameters and depths toward sides and apices of elytra. Hind wings present, functional.
Legs (Figs 16–18) moderately long and slender, lacking male secondary sexual modifications. Fore (Fig. 16) and middle (Fig. 17) leg with subtriangular trochanter, clavate femur with slender, nearly cylindrical proximal half and nearly straight tibia; hind leg (Fig. 18) with long trochanter conspicuously broadened in distal region, femur with broad and strongly flattened proximal half bearing scale-like microsculpture and a trace of barely discernible pit on its external surface, tibia slightly curved near base. All tarsi slender and subcylindrical, protarsus not modified, but ventral surface of tarsomeres 1–4 bearing slightly longer setae than those on remaining legs.
Aedeagus (Figs 23–26) strongly elongate, AeL 0.30 mm; median lobe divided by stalk-like region into tubular proximal portion and much broader but shorter distal capsular portion; in dorsal view basal region broadest near its middle, narrowest site as wide as half width of basal region and about 1/3 as wide as width of distal region; in lateral view stalk-like portion extremely narrow and curved dorsad. Distal region in dorsal view broadest near its base, with a pair of basal translucent subtriangular lobes on sides of stalk-like portion. Dorsally open ostium complex, with symmetrical external structures; endophallus with asymmetrical median capsular structure situated near base of broadened distal aedeagal region. Traces of parameres fused with median lobe can be seen on dorsal surface of tubular proximal region of median lobe.
Female. Externally indistinguishable from male. Only one female was available for measurements: BL 1.43 mm; HL 0.25 mm, HW 0.29 mm, AnL 0.73 mm; PL 0.40 mm, PW 0.39 mm; EL 0.78 mm, EW 0.55 mm, EI 1.41. Spermatheca (Fig. 27) darkly sclerotized, strongly elongate and symmetrical, length 0.13 mm.
Distribution. Honshu (prefectures Nara and newly recorded from Fukui-ken), Japan.
Remarks. I collected this species from under bark of dead deciduous trees, the one in Nara most likely Quercus sessilifolia Blume, a large, dead standing tree in a shaded forest on WS slope of Mt. Kasuga.
description: Published as part of Jałoszyński, Paweł, 2022, Rediscovery and re (re) description of Scydmaenus kasuganus Franz, the only Japanese species of the subgenus Mascarensia Franz (Coleoptera, Staphylinidae, Scydmaeninae), pp. 38-48 in Zootaxa 5093 (1) on pages 39-45, DOI: 10.11646/zootaxa.5093.1.2, http://zenodo.org/record/5900990